@chapter Filtering Introduction @c man begin FILTERING INTRODUCTION Filtering in FFmpeg is enabled through the libavfilter library. In libavfilter, a filter can have multiple inputs and multiple outputs. To illustrate the sorts of things that are possible, we consider the following filtergraph. @example [main] input --> split ---------------------> overlay --> output | ^ |[tmp] [flip]| +-----> crop --> vflip -------+ @end example This filtergraph splits the input stream in two streams, then sends one stream through the crop filter and the vflip filter, before merging it back with the other stream by overlaying it on top. You can use the following command to achieve this: @example ffmpeg -i INPUT -vf "split [main][tmp]; [tmp] crop=iw:ih/2:0:0, vflip [flip]; [main][flip] overlay=0:H/2" OUTPUT @end example The result will be that the top half of the video is mirrored onto the bottom half of the output video. Filters in the same linear chain are separated by commas, and distinct linear chains of filters are separated by semicolons. In our example, @var{crop,vflip} are in one linear chain, @var{split} and @var{overlay} are separately in another. The points where the linear chains join are labelled by names enclosed in square brackets. In the example, the split filter generates two outputs that are associated to the labels @var{[main]} and @var{[tmp]}. The stream sent to the second output of @var{split}, labelled as @var{[tmp]}, is processed through the @var{crop} filter, which crops away the lower half part of the video, and then vertically flipped. The @var{overlay} filter takes in input the first unchanged output of the split filter (which was labelled as @var{[main]}), and overlay on its lower half the output generated by the @var{crop,vflip} filterchain. Some filters take in input a list of parameters: they are specified after the filter name and an equal sign, and are separated from each other by a colon. There exist so-called @var{source filters} that do not have an audio/video input, and @var{sink filters} that will not have audio/video output. @c man end FILTERING INTRODUCTION @chapter graph2dot @c man begin GRAPH2DOT The @file{graph2dot} program included in the FFmpeg @file{tools} directory can be used to parse a filtergraph description and issue a corresponding textual representation in the dot language. Invoke the command: @example graph2dot -h @end example to see how to use @file{graph2dot}. You can then pass the dot description to the @file{dot} program (from the graphviz suite of programs) and obtain a graphical representation of the filtergraph. For example the sequence of commands: @example echo @var{GRAPH_DESCRIPTION} | \ tools/graph2dot -o graph.tmp && \ dot -Tpng graph.tmp -o graph.png && \ display graph.png @end example can be used to create and display an image representing the graph described by the @var{GRAPH_DESCRIPTION} string. Note that this string must be a complete self-contained graph, with its inputs and outputs explicitly defined. For example if your command line is of the form: @example ffmpeg -i infile -vf scale=640:360 outfile @end example your @var{GRAPH_DESCRIPTION} string will need to be of the form: @example nullsrc,scale=640:360,nullsink @end example you may also need to set the @var{nullsrc} parameters and add a @var{format} filter in order to simulate a specific input file. @c man end GRAPH2DOT @chapter Filtergraph description @c man begin FILTERGRAPH DESCRIPTION A filtergraph is a directed graph of connected filters. It can contain cycles, and there can be multiple links between a pair of filters. Each link has one input pad on one side connecting it to one filter from which it takes its input, and one output pad on the other side connecting it to one filter accepting its output. Each filter in a filtergraph is an instance of a filter class registered in the application, which defines the features and the number of input and output pads of the filter. A filter with no input pads is called a "source", and a filter with no output pads is called a "sink". @anchor{Filtergraph syntax} @section Filtergraph syntax A filtergraph has a textual representation, which is recognized by the @option{-filter}/@option{-vf} and @option{-filter_complex} options in @command{ffmpeg} and @option{-vf} in @command{ffplay}, and by the @code{avfilter_graph_parse()}/@code{avfilter_graph_parse2()} functions defined in @file{libavfilter/avfilter.h}. A filterchain consists of a sequence of connected filters, each one connected to the previous one in the sequence. A filterchain is represented by a list of ","-separated filter descriptions. A filtergraph consists of a sequence of filterchains. A sequence of filterchains is represented by a list of ";"-separated filterchain descriptions. A filter is represented by a string of the form: [@var{in_link_1}]...[@var{in_link_N}]@var{filter_name}=@var{arguments}[@var{out_link_1}]...[@var{out_link_M}] @var{filter_name} is the name of the filter class of which the described filter is an instance of, and has to be the name of one of the filter classes registered in the program. The name of the filter class is optionally followed by a string "=@var{arguments}". @var{arguments} is a string which contains the parameters used to initialize the filter instance. It may have one of two forms: @itemize @item A ':'-separated list of @var{key=value} pairs. @item A ':'-separated list of @var{value}. In this case, the keys are assumed to be the option names in the order they are declared. E.g. the @code{fade} filter declares three options in this order -- @option{type}, @option{start_frame} and @option{nb_frames}. Then the parameter list @var{in:0:30} means that the value @var{in} is assigned to the option @option{type}, @var{0} to @option{start_frame} and @var{30} to @option{nb_frames}. @item A ':'-separated list of mixed direct @var{value} and long @var{key=value} pairs. The direct @var{value} must precede the @var{key=value} pairs, and follow the same constraints order of the previous point. The following @var{key=value} pairs can be set in any preferred order. @end itemize If the option value itself is a list of items (e.g. the @code{format} filter takes a list of pixel formats), the items in the list are usually separated by '|'. The list of arguments can be quoted using the character "'" as initial and ending mark, and the character '\' for escaping the characters within the quoted text; otherwise the argument string is considered terminated when the next special character (belonging to the set "[]=;,") is encountered. The name and arguments of the filter are optionally preceded and followed by a list of link labels. A link label allows one to name a link and associate it to a filter output or input pad. The preceding labels @var{in_link_1} ... @var{in_link_N}, are associated to the filter input pads, the following labels @var{out_link_1} ... @var{out_link_M}, are associated to the output pads. When two link labels with the same name are found in the filtergraph, a link between the corresponding input and output pad is created. If an output pad is not labelled, it is linked by default to the first unlabelled input pad of the next filter in the filterchain. For example in the filterchain @example nullsrc, split[L1], [L2]overlay, nullsink @end example the split filter instance has two output pads, and the overlay filter instance two input pads. The first output pad of split is labelled "L1", the first input pad of overlay is labelled "L2", and the second output pad of split is linked to the second input pad of overlay, which are both unlabelled. In a complete filterchain all the unlabelled filter input and output pads must be connected. A filtergraph is considered valid if all the filter input and output pads of all the filterchains are connected. Libavfilter will automatically insert @ref{scale} filters where format conversion is required. It is possible to specify swscale flags for those automatically inserted scalers by prepending @code{sws_flags=@var{flags};} to the filtergraph description. Here is a BNF description of the filtergraph syntax: @example @var{NAME} ::= sequence of alphanumeric characters and '_' @var{LINKLABEL} ::= "[" @var{NAME} "]" @var{LINKLABELS} ::= @var{LINKLABEL} [@var{LINKLABELS}] @var{FILTER_ARGUMENTS} ::= sequence of chars (possibly quoted) @var{FILTER} ::= [@var{LINKLABELS}] @var{NAME} ["=" @var{FILTER_ARGUMENTS}] [@var{LINKLABELS}] @var{FILTERCHAIN} ::= @var{FILTER} [,@var{FILTERCHAIN}] @var{FILTERGRAPH} ::= [sws_flags=@var{flags};] @var{FILTERCHAIN} [;@var{FILTERGRAPH}] @end example @section Notes on filtergraph escaping Filtergraph description composition entails several levels of escaping. See @ref{quoting_and_escaping,,the "Quoting and escaping" section in the ffmpeg-utils(1) manual,ffmpeg-utils} for more information about the employed escaping procedure. A first level escaping affects the content of each filter option value, which may contain the special character @code{:} used to separate values, or one of the escaping characters @code{\'}. A second level escaping affects the whole filter description, which may contain the escaping characters @code{\'} or the special characters @code{[],;} used by the filtergraph description. Finally, when you specify a filtergraph on a shell commandline, you need to perform a third level escaping for the shell special characters contained within it. For example, consider the following string to be embedded in the @ref{drawtext} filter description @option{text} value: @example this is a 'string': may contain one, or more, special characters @end example This string contains the @code{'} special escaping character, and the @code{:} special character, so it needs to be escaped in this way: @example text=this is a \'string\'\: may contain one, or more, special characters @end example A second level of escaping is required when embedding the filter description in a filtergraph description, in order to escape all the filtergraph special characters. Thus the example above becomes: @example drawtext=text=this is a \\\'string\\\'\\: may contain one\, or more\, special characters @end example (note that in addition to the @code{\'} escaping special characters, also @code{,} needs to be escaped). Finally an additional level of escaping is needed when writing the filtergraph description in a shell command, which depends on the escaping rules of the adopted shell. For example, assuming that @code{\} is special and needs to be escaped with another @code{\}, the previous string will finally result in: @example -vf "drawtext=text=this is a \\\\\\'string\\\\\\'\\\\: may contain one\\, or more\\, special characters" @end example @chapter Timeline editing Some filters support a generic @option{enable} option. For the filters supporting timeline editing, this option can be set to an expression which is evaluated before sending a frame to the filter. If the evaluation is non-zero, the filter will be enabled, otherwise the frame will be sent unchanged to the next filter in the filtergraph. The expression accepts the following values: @table @samp @item t timestamp expressed in seconds, NAN if the input timestamp is unknown @item n sequential number of the input frame, starting from 0 @item pos the position in the file of the input frame, NAN if unknown @item w @item h width and height of the input frame if video @end table Additionally, these filters support an @option{enable} command that can be used to re-define the expression. Like any other filtering option, the @option{enable} option follows the same rules. For example, to enable a blur filter (@ref{smartblur}) from 10 seconds to 3 minutes, and a @ref{curves} filter starting at 3 seconds: @example smartblur = enable='between(t,10,3*60)', curves = enable='gte(t,3)' : preset=cross_process @end example @c man end FILTERGRAPH DESCRIPTION @chapter Audio Filters @c man begin AUDIO FILTERS When you configure your FFmpeg build, you can disable any of the existing filters using @code{--disable-filters}. The configure output will show the audio filters included in your build. Below is a description of the currently available audio filters. @section adelay Delay one or more audio channels. Samples in delayed channel are filled with silence. The filter accepts the following option: @table @option @item delays Set list of delays in milliseconds for each channel separated by '|'. At least one delay greater than 0 should be provided. Unused delays will be silently ignored. If number of given delays is smaller than number of channels all remaining channels will not be delayed. @end table @subsection Examples @itemize @item Delay first channel by 1.5 seconds, the third channel by 0.5 seconds and leave the second channel (and any other channels that may be present) unchanged. @example adelay=1500|0|500 @end example @end itemize @section aecho Apply echoing to the input audio. Echoes are reflected sound and can occur naturally amongst mountains (and sometimes large buildings) when talking or shouting; digital echo effects emulate this behaviour and are often used to help fill out the sound of a single instrument or vocal. The time difference between the original signal and the reflection is the @code{delay}, and the loudness of the reflected signal is the @code{decay}. Multiple echoes can have different delays and decays. A description of the accepted parameters follows. @table @option @item in_gain Set input gain of reflected signal. Default is @code{0.6}. @item out_gain Set output gain of reflected signal. Default is @code{0.3}. @item delays Set list of time intervals in milliseconds between original signal and reflections separated by '|'. Allowed range for each @code{delay} is @code{(0 - 90000.0]}. Default is @code{1000}. @item decays Set list of loudnesses of reflected signals separated by '|'. Allowed range for each @code{decay} is @code{(0 - 1.0]}. Default is @code{0.5}. @end table @subsection Examples @itemize @item Make it sound as if there are twice as many instruments as are actually playing: @example aecho=0.8:0.88:60:0.4 @end example @item If delay is very short, then it sound like a (metallic) robot playing music: @example aecho=0.8:0.88:6:0.4 @end example @item A longer delay will sound like an open air concert in the mountains: @example aecho=0.8:0.9:1000:0.3 @end example @item Same as above but with one more mountain: @example aecho=0.8:0.9:1000|1800:0.3|0.25 @end example @end itemize @section aeval Modify an audio signal according to the specified expressions. This filter accepts one or more expressions (one for each channel), which are evaluated and used to modify a corresponding audio signal. It accepts the following parameters: @table @option @item exprs Set the '|'-separated expressions list for each separate channel. If the number of input channels is greater than the number of expressions, the last specified expression is used for the remaining output channels. @item channel_layout, c Set output channel layout. If not specified, the channel layout is specified by the number of expressions. If set to @samp{same}, it will use by default the same input channel layout. @end table Each expression in @var{exprs} can contain the following constants and functions: @table @option @item ch channel number of the current expression @item n number of the evaluated sample, starting from 0 @item s sample rate @item t time of the evaluated sample expressed in seconds @item nb_in_channels @item nb_out_channels input and output number of channels @item val(CH) the value of input channel with number @var{CH} @end table Note: this filter is slow. For faster processing you should use a dedicated filter. @subsection Examples @itemize @item Half volume: @example aeval=val(ch)/2:c=same @end example @item Invert phase of the second channel: @example aeval=val(0)|-val(1) @end example @end itemize @section afade Apply fade-in/out effect to input audio. A description of the accepted parameters follows. @table @option @item type, t Specify the effect type, can be either @code{in} for fade-in, or @code{out} for a fade-out effect. Default is @code{in}. @item start_sample, ss Specify the number of the start sample for starting to apply the fade effect. Default is 0. @item nb_samples, ns Specify the number of samples for which the fade effect has to last. At the end of the fade-in effect the output audio will have the same volume as the input audio, at the end of the fade-out transition the output audio will be silence. Default is 44100. @item start_time, st Specify the start time of the fade effect. Default is 0. The value must be specified as a time duration; see @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils} for the accepted syntax. If set this option is used instead of @var{start_sample}. @item duration, d Specify the duration of the fade effect. See @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils} for the accepted syntax. At the end of the fade-in effect the output audio will have the same volume as the input audio, at the end of the fade-out transition the output audio will be silence. By default the duration is determined by @var{nb_samples}. If set this option is used instead of @var{nb_samples}. @item curve Set curve for fade transition. It accepts the following values: @table @option @item tri select triangular, linear slope (default) @item qsin select quarter of sine wave @item hsin select half of sine wave @item esin select exponential sine wave @item log select logarithmic @item par select inverted parabola @item qua select quadratic @item cub select cubic @item squ select square root @item cbr select cubic root @end table @end table @subsection Examples @itemize @item Fade in first 15 seconds of audio: @example afade=t=in:ss=0:d=15 @end example @item Fade out last 25 seconds of a 900 seconds audio: @example afade=t=out:st=875:d=25 @end example @end itemize @anchor{aformat} @section aformat Set output format constraints for the input audio. The framework will negotiate the most appropriate format to minimize conversions. It accepts the following parameters: @table @option @item sample_fmts A '|'-separated list of requested sample formats. @item sample_rates A '|'-separated list of requested sample rates. @item channel_layouts A '|'-separated list of requested channel layouts. See @ref{channel layout syntax,,the Channel Layout section in the ffmpeg-utils(1) manual,ffmpeg-utils} for the required syntax. @end table If a parameter is omitted, all values are allowed. Force the output to either unsigned 8-bit or signed 16-bit stereo @example aformat=sample_fmts=u8|s16:channel_layouts=stereo @end example @section allpass Apply a two-pole all-pass filter with central frequency (in Hz) @var{frequency}, and filter-width @var{width}. An all-pass filter changes the audio's frequency to phase relationship without changing its frequency to amplitude relationship. The filter accepts the following options: @table @option @item frequency, f Set frequency in Hz. @item width_type Set method to specify band-width of filter. @table @option @item h Hz @item q Q-Factor @item o octave @item s slope @end table @item width, w Specify the band-width of a filter in width_type units. @end table @section amerge Merge two or more audio streams into a single multi-channel stream. The filter accepts the following options: @table @option @item inputs Set the number of inputs. Default is 2. @end table If the channel layouts of the inputs are disjoint, and therefore compatible, the channel layout of the output will be set accordingly and the channels will be reordered as necessary. If the channel layouts of the inputs are not disjoint, the output will have all the channels of the first input then all the channels of the second input, in that order, and the channel layout of the output will be the default value corresponding to the total number of channels. For example, if the first input is in 2.1 (FL+FR+LF) and the second input is FC+BL+BR, then the output will be in 5.1, with the channels in the following order: a1, a2, b1, a3, b2, b3 (a1 is the first channel of the first input, b1 is the first channel of the second input). On the other hand, if both input are in stereo, the output channels will be in the default order: a1, a2, b1, b2, and the channel layout will be arbitrarily set to 4.0, which may or may not be the expected value. All inputs must have the same sample rate, and format. If inputs do not have the same duration, the output will stop with the shortest. @subsection Examples @itemize @item Merge two mono files into a stereo stream: @example amovie=left.wav [l] ; amovie=right.mp3 [r] ; [l] [r] amerge @end example @item Multiple merges assuming 1 video stream and 6 audio streams in @file{input.mkv}: @example ffmpeg -i input.mkv -filter_complex "[0:1][0:2][0:3][0:4][0:5][0:6] amerge=inputs=6" -c:a pcm_s16le output.mkv @end example @end itemize @section amix Mixes multiple audio inputs into a single output. Note that this filter only supports float samples (the @var{amerge} and @var{pan} audio filters support many formats). If the @var{amix} input has integer samples then @ref{aresample} will be automatically inserted to perform the conversion to float samples. For example @example ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT @end example will mix 3 input audio streams to a single output with the same duration as the first input and a dropout transition time of 3 seconds. It accepts the following parameters: @table @option @item inputs The number of inputs. If unspecified, it defaults to 2. @item duration How to determine the end-of-stream. @table @option @item longest The duration of the longest input. (default) @item shortest The duration of the shortest input. @item first The duration of the first input. @end table @item dropout_transition The transition time, in seconds, for volume renormalization when an input stream ends. The default value is 2 seconds. @end table @section anull Pass the audio source unchanged to the output. @section apad Pad the end of an audio stream with silence. This can be used together with @command{ffmpeg} @option{-shortest} to extend audio streams to the same length as the video stream. A description of the accepted options follows. @table @option @item packet_size Set silence packet size. Default value is 4096. @item pad_len Set the number of samples of silence to add to the end. After the value is reached, the stream is terminated. This option is mutually exclusive with @option{whole_len}. @item whole_len Set the minimum total number of samples in the output audio stream. If the value is longer than the input audio length, silence is added to the end, until the value is reached. This option is mutually exclusive with @option{pad_len}. @end table If neither the @option{pad_len} nor the @option{whole_len} option is set, the filter will add silence to the end of the input stream indefinitely. @subsection Examples @itemize @item Add 1024 samples of silence to the end of the input: @example apad=pad_len=1024 @end example @item Make sure the audio output will contain at least 10000 samples, pad the input with silence if required: @example apad=whole_len=10000 @end example @item Use @command{ffmpeg} to pad the audio input with silence, so that the video stream will always result the shortest and will be converted until the end in the output file when using the @option{shortest} option: @example ffmpeg -i VIDEO -i AUDIO -filter_complex "[1:0]apad" -shortest OUTPUT @end example @end itemize @section aphaser Add a phasing effect to the input audio. A phaser filter creates series of peaks and troughs in the frequency spectrum. The position of the peaks and troughs are modulated so that they vary over time, creating a sweeping effect. A description of the accepted parameters follows. @table @option @item in_gain Set input gain. Default is 0.4. @item out_gain Set output gain. Default is 0.74 @item delay Set delay in milliseconds. Default is 3.0. @item decay Set decay. Default is 0.4. @item speed Set modulation speed in Hz. Default is 0.5. @item type Set modulation type. Default is triangular. It accepts the following values: @table @samp @item triangular, t @item sinusoidal, s @end table @end table @anchor{aresample} @section aresample Resample the input audio to the specified parameters, using the libswresample library. If none are specified then the filter will automatically convert between its input and output. This filter is also able to stretch/squeeze the audio data to make it match the timestamps or to inject silence / cut out audio to make it match the timestamps, do a combination of both or do neither. The filter accepts the syntax [@var{sample_rate}:]@var{resampler_options}, where @var{sample_rate} expresses a sample rate and @var{resampler_options} is a list of @var{key}=@var{value} pairs, separated by ":". See the ffmpeg-resampler manual for the complete list of supported options. @subsection Examples @itemize @item Resample the input audio to 44100Hz: @example aresample=44100 @end example @item Stretch/squeeze samples to the given timestamps, with a maximum of 1000 samples per second compensation: @example aresample=async=1000 @end example @end itemize @section asetnsamples Set the number of samples per each output audio frame. The last output packet may contain a different number of samples, as the filter will flush all the remaining samples when the input audio signal its end. The filter accepts the following options: @table @option @item nb_out_samples, n Set the number of frames per each output audio frame. The number is intended as the number of samples @emph{per each channel}. Default value is 1024. @item pad, p If set to 1, the filter will pad the last audio frame with zeroes, so that the last frame will contain the same number of samples as the previous ones. Default value is 1. @end table For example, to set the number of per-frame samples to 1234 and disable padding for the last frame, use: @example asetnsamples=n=1234:p=0 @end example @section asetrate Set the sample rate without altering the PCM data. This will result in a change of speed and pitch. The filter accepts the following options: @table @option @item sample_rate, r Set the output sample rate. Default is 44100 Hz. @end table @section ashowinfo Show a line containing various information for each input audio frame. The input audio is not modified. The shown line contains a sequence of key/value pairs of the form @var{key}:@var{value}. The following values are shown in the output: @table @option @item n The (sequential) number of the input frame, starting from 0. @item pts The presentation timestamp of the input frame, in time base units; the time base depends on the filter input pad, and is usually 1/@var{sample_rate}. @item pts_time The presentation timestamp of the input frame in seconds. @item pos position of the frame in the input stream, -1 if this information in unavailable and/or meaningless (for example in case of synthetic audio) @item fmt The sample format. @item chlayout The channel layout. @item rate The sample rate for the audio frame. @item nb_samples The number of samples (per channel) in the frame. @item checksum The Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio, the data is treated as if all the planes were concatenated. @item plane_checksums A list of Adler-32 checksums for each data plane. @end table @section astats Display time domain statistical information about the audio channels. Statistics are calculated and displayed for each audio channel and, where applicable, an overall figure is also given. It accepts the following option: @table @option @item length Short window length in seconds, used for peak and trough RMS measurement. Default is @code{0.05} (50 miliseconds). Allowed range is @code{[0.1 - 10]}. @end table A description of each shown parameter follows: @table @option @item DC offset Mean amplitude displacement from zero. @item Min level Minimal sample level. @item Max level Maximal sample level. @item Peak level dB @item RMS level dB Standard peak and RMS level measured in dBFS. @item RMS peak dB @item RMS trough dB Peak and trough values for RMS level measured over a short window. @item Crest factor Standard ratio of peak to RMS level (note: not in dB). @item Flat factor Flatness (i.e. consecutive samples with the same value) of the signal at its peak levels (i.e. either @var{Min level} or @var{Max level}). @item Peak count Number of occasions (not the number of samples) that the signal attained either @var{Min level} or @var{Max level}. @end table @section astreamsync Forward two audio streams and control the order the buffers are forwarded. The filter accepts the following options: @table @option @item expr, e Set the expression deciding which stream should be forwarded next: if the result is negative, the first stream is forwarded; if the result is positive or zero, the second stream is forwarded. It can use the following variables: @table @var @item b1 b2 number of buffers forwarded so far on each stream @item s1 s2 number of samples forwarded so far on each stream @item t1 t2 current timestamp of each stream @end table The default value is @code{t1-t2}, which means to always forward the stream that has a smaller timestamp. @end table @subsection Examples Stress-test @code{amerge} by randomly sending buffers on the wrong input, while avoiding too much of a desynchronization: @example amovie=file.ogg [a] ; amovie=file.mp3 [b] ; [a] [b] astreamsync=(2*random(1))-1+tanh(5*(t1-t2)) [a2] [b2] ; [a2] [b2] amerge @end example @section asyncts Synchronize audio data with timestamps by squeezing/stretching it and/or dropping samples/adding silence when needed. This filter is not built by default, please use @ref{aresample} to do squeezing/stretching. It accepts the following parameters: @table @option @item compensate Enable stretching/squeezing the data to make it match the timestamps. Disabled by default. When disabled, time gaps are covered with silence. @item min_delta The minimum difference between timestamps and audio data (in seconds) to trigger adding/dropping samples. The default value is 0.1. If you get an imperfect sync with this filter, try setting this parameter to 0. @item max_comp The maximum compensation in samples per second. Only relevant with compensate=1. The default value is 500. @item first_pts Assume that the first PTS should be this value. The time base is 1 / sample rate. This allows for padding/trimming at the start of the stream. By default, no assumption is made about the first frame's expected PTS, so no padding or trimming is done. For example, this could be set to 0 to pad the beginning with silence if an audio stream starts after the video stream or to trim any samples with a negative PTS due to encoder delay. @end table @section atempo Adjust audio tempo. The filter accepts exactly one parameter, the audio tempo. If not specified then the filter will assume nominal 1.0 tempo. Tempo must be in the [0.5, 2.0] range. @subsection Examples @itemize @item Slow down audio to 80% tempo: @example atempo=0.8 @end example @item To speed up audio to 125% tempo: @example atempo=1.25 @end example @end itemize @section atrim Trim the input so that the output contains one continuous subpart of the input. It accepts the following parameters: @table @option @item start Timestamp (in seconds) of the start of the section to keep. I.e. the audio sample with the timestamp @var{start} will be the first sample in the output. @item end Specify time of the first audio sample that will be dropped, i.e. the audio sample immediately preceding the one with the timestamp @var{end} will be the last sample in the output. @item start_pts Same as @var{start}, except this option sets the start timestamp in samples instead of seconds. @item end_pts Same as @var{end}, except this option sets the end timestamp in samples instead of seconds. @item duration The maximum duration of the output in seconds. @item start_sample The number of the first sample that should be output. @item end_sample The number of the first sample that should be dropped. @end table @option{start}, @option{end}, and @option{duration} are expressed as time duration specifications; see @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}. Note that the first two sets of the start/end options and the @option{duration} option look at the frame timestamp, while the _sample options simply count the samples that pass through the filter. So start/end_pts and start/end_sample will give different results when the timestamps are wrong, inexact or do not start at zero. Also note that this filter does not modify the timestamps. If you wish to have the output timestamps start at zero, insert the asetpts filter after the atrim filter. If multiple start or end options are set, this filter tries to be greedy and keep all samples that match at least one of the specified constraints. To keep only the part that matches all the constraints at once, chain multiple atrim filters. The defaults are such that all the input is kept. So it is possible to set e.g. just the end values to keep everything before the specified time. Examples: @itemize @item Drop everything except the second minute of input: @example ffmpeg -i INPUT -af atrim=60:120 @end example @item Keep only the first 1000 samples: @example ffmpeg -i INPUT -af atrim=end_sample=1000 @end example @end itemize @section bandpass Apply a two-pole Butterworth band-pass filter with central frequency @var{frequency}, and (3dB-point) band-width width. The @var{csg} option selects a constant skirt gain (peak gain = Q) instead of the default: constant 0dB peak gain. The filter roll off at 6dB per octave (20dB per decade). The filter accepts the following options: @table @option @item frequency, f Set the filter's central frequency. Default is @code{3000}. @item csg Constant skirt gain if set to 1. Defaults to 0. @item width_type Set method to specify band-width of filter. @table @option @item h Hz @item q Q-Factor @item o octave @item s slope @end table @item width, w Specify the band-width of a filter in width_type units. @end table @section bandreject Apply a two-pole Butterworth band-reject filter with central frequency @var{frequency}, and (3dB-point) band-width @var{width}. The filter roll off at 6dB per octave (20dB per decade). The filter accepts the following options: @table @option @item frequency, f Set the filter's central frequency. Default is @code{3000}. @item width_type Set method to specify band-width of filter. @table @option @item h Hz @item q Q-Factor @item o octave @item s slope @end table @item width, w Specify the band-width of a filter in width_type units. @end table @section bass Boost or cut the bass (lower) frequencies of the audio using a two-pole shelving filter with a response similar to that of a standard hi-fi's tone-controls. This is also known as shelving equalisation (EQ). The filter accepts the following options: @table @option @item gain, g Give the gain at 0 Hz. Its useful range is about -20 (for a large cut) to +20 (for a large boost). Beware of clipping when using a positive gain. @item frequency, f Set the filter's central frequency and so can be used to extend or reduce the frequency range to be boosted or cut. The default value is @code{100} Hz. @item width_type Set method to specify band-width of filter. @table @option @item h Hz @item q Q-Factor @item o octave @item s slope @end table @item width, w Determine how steep is the filter's shelf transition. @end table @section biquad Apply a biquad IIR filter with the given coefficients. Where @var{b0}, @var{b1}, @var{b2} and @var{a0}, @var{a1}, @var{a2} are the numerator and denominator coefficients respectively. @section bs2b Bauer stereo to binaural transformation, which improves headphone listening of stereo audio records. It accepts the following parameters: @table @option @item profile Pre-defined crossfeed level. @table @option @item default Default level (fcut=700, feed=50). @item cmoy Chu Moy circuit (fcut=700, feed=60). @item jmeier Jan Meier circuit (fcut=650, feed=95). @end table @item fcut Cut frequency (in Hz). @item feed Feed level (in Hz). @end table @section channelmap Remap input channels to new locations. It accepts the following parameters: @table @option @item channel_layout The channel layout of the output stream. @item map Map channels from input to output. The argument is a '|'-separated list of mappings, each in the @code{@var{in_channel}-@var{out_channel}} or @var{in_channel} form. @var{in_channel} can be either the name of the input channel (e.g. FL for front left) or its index in the input channel layout. @var{out_channel} is the name of the output channel or its index in the output channel layout. If @var{out_channel} is not given then it is implicitly an index, starting with zero and increasing by one for each mapping. @end table If no mapping is present, the filter will implicitly map input channels to output channels, preserving indices. For example, assuming a 5.1+downmix input MOV file, @example ffmpeg -i in.mov -filter 'channelmap=map=DL-FL|DR-FR' out.wav @end example will create an output WAV file tagged as stereo from the downmix channels of the input. To fix a 5.1 WAV improperly encoded in AAC's native channel order @example ffmpeg -i in.wav -filter 'channelmap=1|2|0|5|3|4:channel_layout=5.1' out.wav @end example @section channelsplit Split each channel from an input audio stream into a separate output stream. It accepts the following parameters: @table @option @item channel_layout The channel layout of the input stream. The default is "stereo". @end table For example, assuming a stereo input MP3 file, @example ffmpeg -i in.mp3 -filter_complex channelsplit out.mkv @end example will create an output Matroska file with two audio streams, one containing only the left channel and the other the right channel. Split a 5.1 WAV file into per-channel files: @example ffmpeg -i in.wav -filter_complex 'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]' -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]' front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]' side_right.wav @end example @section compand Compress or expand the audio's dynamic range. It accepts the following parameters: @table @option @item attacks @item decays A list of times in seconds for each channel over which the instantaneous level of the input signal is averaged to determine its volume. @var{attacks} refers to increase of volume and @var{decays} refers to decrease of volume. For most situations, the attack time (response to the audio getting louder) should be shorter than the decay time, because the human ear is more sensitive to sudden loud audio than sudden soft audio. A typical value for attack is 0.3 seconds and a typical value for decay is 0.8 seconds. @item points A list of points for the transfer function, specified in dB relative to the maximum possible signal amplitude. Each key points list must be defined using the following syntax: @code{x0/y0|x1/y1|x2/y2|....} or @code{x0/y0 x1/y1 x2/y2 ....} The input values must be in strictly increasing order but the transfer function does not have to be monotonically rising. The point @code{0/0} is assumed but may be overridden (by @code{0/out-dBn}). Typical values for the transfer function are @code{-70/-70|-60/-20}. @item soft-knee Set the curve radius in dB for all joints. It defaults to 0.01. @item gain Set the additional gain in dB to be applied at all points on the transfer function. This allows for easy adjustment of the overall gain. It defaults to 0. @item volume Set an initial volume, in dB, to be assumed for each channel when filtering starts. This permits the user to supply a nominal level initially, so that, for example, a very large gain is not applied to initial signal levels before the companding has begun to operate. A typical value for audio which is initially quiet is -90 dB. It defaults to 0. @item delay Set a delay, in seconds. The input audio is analyzed immediately, but audio is delayed before being fed to the volume adjuster. Specifying a delay approximately equal to the attack/decay times allows the filter to effectively operate in predictive rather than reactive mode. It defaults to 0. @end table @subsection Examples @itemize @item Make music with both quiet and loud passages suitable for listening to in a noisy environment: @example compand=.3|.3:1|1:-90/-60|-60/-40|-40/-30|-20/-20:6:0:-90:0.2 @end example @item A noise gate for when the noise is at a lower level than the signal: @example compand=.1|.1:.2|.2:-900/-900|-50.1/-900|-50/-50:.01:0:-90:.1 @end example @item Here is another noise gate, this time for when the noise is at a higher level than the signal (making it, in some ways, similar to squelch): @example compand=.1|.1:.1|.1:-45.1/-45.1|-45/-900|0/-900:.01:45:-90:.1 @end example @end itemize @section earwax Make audio easier to listen to on headphones. This filter adds `cues' to 44.1kHz stereo (i.e. audio CD format) audio so that when listened to on headphones the stereo image is moved from inside your head (standard for headphones) to outside and in front of the listener (standard for speakers). Ported from SoX. @section equalizer Apply a two-pole peaking equalisation (EQ) filter. With this filter, the signal-level at and around a selected frequency can be increased or decreased, whilst (unlike bandpass and bandreject filters) that at all other frequencies is unchanged. In order to produce complex equalisation curves, this filter can be given several times, each with a different central frequency. The filter accepts the following options: @table @option @item frequency, f Set the filter's central frequency in Hz. @item width_type Set method to specify band-width of filter. @table @option @item h Hz @item q Q-Factor @item o octave @item s slope @end table @item width, w Specify the band-width of a filter in width_type units. @item gain, g Set the required gain or attenuation in dB. Beware of clipping when using a positive gain. @end table @subsection Examples @itemize @item Attenuate 10 dB at 1000 Hz, with a bandwidth of 200 Hz: @example equalizer=f=1000:width_type=h:width=200:g=-10 @end example @item Apply 2 dB gain at 1000 Hz with Q 1 and attenuate 5 dB at 100 Hz with Q 2: @example equalizer=f=1000:width_type=q:width=1:g=2,equalizer=f=100:width_type=q:width=2:g=-5 @end example @end itemize @section flanger Apply a flanging effect to the audio. The filter accepts the following options: @table @option @item delay Set base delay in milliseconds. Range from 0 to 30. Default value is 0. @item depth Set added swep delay in milliseconds. Range from 0 to 10. Default value is 2. @item regen Set percentage regeneneration (delayed signal feedback). Range from -95 to 95. Default value is 0. @item width Set percentage of delayed signal mixed with original. Range from 0 to 100. Default valu is 71. @item speed Set sweeps per second (Hz). Range from 0.1 to 10. Default value is 0.5. @item shape Set swept wave shape, can be @var{triangular} or @var{sinusoidal}. Default value is @var{sinusoidal}. @item phase Set swept wave percentage-shift for multi channel. Range from 0 to 100. Default value is 25. @item interp Set delay-line interpolation, @var{linear} or @var{quadratic}. Default is @var{linear}. @end table @section highpass Apply a high-pass filter with 3dB point frequency. The filter can be either single-pole, or double-pole (the default). The filter roll off at 6dB per pole per octave (20dB per pole per decade). The filter accepts the following options: @table @option @item frequency, f Set frequency in Hz. Default is 3000. @item poles, p Set number of poles. Default is 2. @item width_type Set method to specify band-width of filter. @table @option @item h Hz @item q Q-Factor @item o octave @item s slope @end table @item width, w Specify the band-width of a filter in width_type units. Applies only to double-pole filter. The default is 0.707q and gives a Butterworth response. @end table @section join Join multiple input streams into one multi-channel stream. It accepts the following parameters: @table @option @item inputs The number of input streams. It defaults to 2. @item channel_layout The desired output channel layout. It defaults to stereo. @item map Map channels from inputs to output. The argument is a '|'-separated list of mappings, each in the @code{@var{input_idx}.@var{in_channel}-@var{out_channel}} form. @var{input_idx} is the 0-based index of the input stream. @var{in_channel} can be either the name of the input channel (e.g. FL for front left) or its index in the specified input stream. @var{out_channel} is the name of the output channel. @end table The filter will attempt to guess the mappings when they are not specified explicitly. It does so by first trying to find an unused matching input channel and if that fails it picks the first unused input channel. Join 3 inputs (with properly set channel layouts): @example ffmpeg -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT @end example Build a 5.1 output from 6 single-channel streams: @example ffmpeg -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex 'join=inputs=6:channel_layout=5.1:map=0.0-FL|1.0-FR|2.0-FC|3.0-SL|4.0-SR|5.0-LFE' out @end example @section ladspa Load a LADSPA (Linux Audio Developer's Simple Plugin API) plugin. To enable compilation of this filter you need to configure FFmpeg with @code{--enable-ladspa}. @table @option @item file, f Specifies the name of LADSPA plugin library to load. If the environment variable @env{LADSPA_PATH} is defined, the LADSPA plugin is searched in each one of the directories specified by the colon separated list in @env{LADSPA_PATH}, otherwise in the standard LADSPA paths, which are in this order: @file{HOME/.ladspa/lib/}, @file{/usr/local/lib/ladspa/}, @file{/usr/lib/ladspa/}. @item plugin, p Specifies the plugin within the library. Some libraries contain only one plugin, but others contain many of them. If this is not set filter will list all available plugins within the specified library. @item controls, c Set the '|' separated list of controls which are zero or more floating point values that determine the behavior of the loaded plugin (for example delay, threshold or gain). Controls need to be defined using the following syntax: c0=@var{value0}|c1=@var{value1}|c2=@var{value2}|..., where @var{valuei} is the value set on the @var{i}-th control. If @option{controls} is set to @code{help}, all available controls and their valid ranges are printed. @item sample_rate, s Specify the sample rate, default to 44100. Only used if plugin have zero inputs. @item nb_samples, n Set the number of samples per channel per each output frame, default is 1024. Only used if plugin have zero inputs. @item duration, d Set the minimum duration of the sourced audio. See @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils} for the accepted syntax. Note that the resulting duration may be greater than the specified duration, as the generated audio is always cut at the end of a complete frame. If not specified, or the expressed duration is negative, the audio is supposed to be generated forever. Only used if plugin have zero inputs. @end table @subsection Examples @itemize @item List all available plugins within amp (LADSPA example plugin) library: @example ladspa=file=amp @end example @item List all available controls and their valid ranges for @code{vcf_notch} plugin from @code{VCF} library: @example ladspa=f=vcf:p=vcf_notch:c=help @end example @item Simulate low quality audio equipment using @code{Computer Music Toolkit} (CMT) plugin library: @example ladspa=file=cmt:plugin=lofi:controls=c0=22|c1=12|c2=12 @end example @item Add reverberation to the audio using TAP-plugins (Tom's Audio Processing plugins): @example ladspa=file=tap_reverb:tap_reverb @end example @item Generate white noise, with 0.2 amplitude: @example ladspa=file=cmt:noise_source_white:c=c0=.2 @end example @item Generate 20 bpm clicks using plugin @code{C* Click - Metronome} from the @code{C* Audio Plugin Suite} (CAPS) library: @example ladspa=file=caps:Click:c=c1=20' @end example @item Apply @code{C* Eq10X2 - Stereo 10-band equaliser} effect: @example ladspa=caps:Eq10X2:c=c0=-48|c9=-24|c3=12|c4=2 @end example @end itemize @subsection Commands This filter supports the following commands: @table @option @item cN Modify the @var{N}-th control value. If the specified value is not valid, it is ignored and prior one is kept. @end table @section lowpass Apply a low-pass filter with 3dB point frequency. The filter can be either single-pole or double-pole (the default). The filter roll off at 6dB per pole per octave (20dB per pole per decade). The filter accepts the following options: @table @option @item frequency, f Set frequency in Hz. Default is 500. @item poles, p Set number of poles. Default is 2. @item width_type Set method to specify band-width of filter. @table @option @item h Hz @item q Q-Factor @item o octave @item s slope @end table @item width, w Specify the band-width of a filter in width_type units. Applies only to double-pole filter. The default is 0.707q and gives a Butterworth response. @end table @section pan Mix channels with specific gain levels. The filter accepts the output channel layout followed by a set of channels definitions. This filter is also designed to efficiently remap the channels of an audio stream. The filter accepts parameters of the form: "@var{l}|@var{outdef}|@var{outdef}|..." @table @option @item l output channel layout or number of channels @item outdef output channel specification, of the form: "@var{out_name}=[@var{gain}*]@var{in_name}[+[@var{gain}*]@var{in_name}...]" @item out_name output channel to define, either a channel name (FL, FR, etc.) or a channel number (c0, c1, etc.) @item gain multiplicative coefficient for the channel, 1 leaving the volume unchanged @item in_name input channel to use, see out_name for details; it is not possible to mix named and numbered input channels @end table If the `=' in a channel specification is replaced by `<', then the gains for that specification will be renormalized so that the total is 1, thus avoiding clipping noise. @subsection Mixing examples For example, if you want to down-mix from stereo to mono, but with a bigger factor for the left channel: @example pan=1c|c0=0.9*c0+0.1*c1 @end example A customized down-mix to stereo that works automatically for 3-, 4-, 5- and 7-channels surround: @example pan=stereo| FL < FL + 0.5*FC + 0.6*BL + 0.6*SL | FR < FR + 0.5*FC + 0.6*BR + 0.6*SR @end example Note that @command{ffmpeg} integrates a default down-mix (and up-mix) system that should be preferred (see "-ac" option) unless you have very specific needs. @subsection Remapping examples The channel remapping will be effective if, and only if: @itemize @item gain coefficients are zeroes or ones, @item only one input per channel output, @end itemize If all these conditions are satisfied, the filter will notify the user ("Pure channel mapping detected"), and use an optimized and lossless method to do the remapping. For example, if you have a 5.1 source and want a stereo audio stream by dropping the extra channels: @example pan="stereo| c0=FL | c1=FR" @end example Given the same source, you can also switch front left and front right channels and keep the input channel layout: @example pan="5.1| c0=c1 | c1=c0 | c2=c2 | c3=c3 | c4=c4 | c5=c5" @end example If the input is a stereo audio stream, you can mute the front left channel (and still keep the stereo channel layout) with: @example pan="stereo|c1=c1" @end example Still with a stereo audio stream input, you can copy the right channel in both front left and right: @example pan="stereo| c0=FR | c1=FR" @end example @section replaygain ReplayGain scanner filter. This filter takes an audio stream as an input and outputs it unchanged. At end of filtering it displays @code{track_gain} and @code{track_peak}. @section resample Convert the audio sample format, sample rate and channel layout. It is not meant to be used directly. @section silencedetect Detect silence in an audio stream. This filter logs a message when it detects that the input audio volume is less or equal to a noise tolerance value for a duration greater or equal to the minimum detected noise duration. The printed times and duration are expressed in seconds. The filter accepts the following options: @table @option @item duration, d Set silence duration until notification (default is 2 seconds). @item noise, n Set noise tolerance. Can be specified in dB (in case "dB" is appended to the specified value) or amplitude ratio. Default is -60dB, or 0.001. @end table @subsection Examples @itemize @item Detect 5 seconds of silence with -50dB noise tolerance: @example silencedetect=n=-50dB:d=5 @end example @item Complete example with @command{ffmpeg} to detect silence with 0.0001 noise tolerance in @file{silence.mp3}: @example ffmpeg -i silence.mp3 -af silencedetect=noise=0.0001 -f null - @end example @end itemize @section silenceremove Remove silence from the beginning, middle or end of the audio. The filter accepts the following options: @table @option @item start_periods This value is used to indicate if audio should be trimmed at beginning of the audio. A value of zero indicates no silence should be trimmed from the beginning. When specifying a non-zero value, it trims audio up until it finds non-silence. Normally, when trimming silence from beginning of audio the @var{start_periods} will be @code{1} but it can be increased to higher values to trim all audio up to specific count of non-silence periods. Default value is @code{0}. @item start_duration Specify the amount of time that non-silence must be detected before it stops trimming audio. By increasing the duration, bursts of noises can be treated as silence and trimmed off. Default value is @code{0}. @item start_threshold This indicates what sample value should be treated as silence. For digital audio, a value of @code{0} may be fine but for audio recorded from analog, you may wish to increase the value to account for background noise. Can be specified in dB (in case "dB" is appended to the specified value) or amplitude ratio. Default value is @code{0}. @item stop_periods Set the count for trimming silence from the end of audio. To remove silence from the middle of a file, specify a @var{stop_periods} that is negative. This value is then threated as a positive value and is used to indicate the effect should restart processing as specified by @var{start_periods}, making it suitable for removing periods of silence in the middle of the audio. Default value is @code{0}. @item stop_duration Specify a duration of silence that must exist before audio is not copied any more. By specifying a higher duration, silence that is wanted can be left in the audio. Default value is @code{0}. @item stop_threshold This is the same as @option{start_threshold} but for trimming silence from the end of audio. Can be specified in dB (in case "dB" is appended to the specified value) or amplitude ratio. Default value is @code{0}. @item leave_silence This indicate that @var{stop_duration} length of audio should be left intact at the beginning of each period of silence. For example, if you want to remove long pauses between words but do not want to remove the pauses completely. Default value is @code{0}. @end table @subsection Examples @itemize @item The following example shows how this filter can be used to start a recording that does not contain the delay at the start which usually occurs between pressing the record button and the start of the performance: @example silenceremove=1:5:0.02 @end example @end itemize @section treble Boost or cut treble (upper) frequencies of the audio using a two-pole shelving filter with a response similar to that of a standard hi-fi's tone-controls. This is also known as shelving equalisation (EQ). The filter accepts the following options: @table @option @item gain, g Give the gain at whichever is the lower of ~22 kHz and the Nyquist frequency. Its useful range is about -20 (for a large cut) to +20 (for a large boost). Beware of clipping when using a positive gain. @item frequency, f Set the filter's central frequency and so can be used to extend or reduce the frequency range to be boosted or cut. The default value is @code{3000} Hz. @item width_type Set method to specify band-width of filter. @table @option @item h Hz @item q Q-Factor @item o octave @item s slope @end table @item width, w Determine how steep is the filter's shelf transition. @end table @section volume Adjust the input audio volume. It accepts the following parameters: @table @option @item volume Set audio volume expression. Output values are clipped to the maximum value. The output audio volume is given by the relation: @example @var{output_volume} = @var{volume} * @var{input_volume} @end example The default value for @var{volume} is "1.0". @item precision This parameter represents the mathematical precision. It determines which input sample formats will be allowed, which affects the precision of the volume scaling. @table @option @item fixed 8-bit fixed-point; this limits input sample format to U8, S16, and S32. @item float 32-bit floating-point; this limits input sample format to FLT. (default) @item double 64-bit floating-point; this limits input sample format to DBL. @end table @item replaygain Choose the behaviour on encountering ReplayGain side data in input frames. @table @option @item drop Remove ReplayGain side data, ignoring its contents (the default). @item ignore Ignore ReplayGain side data, but leave it in the frame. @item track Prefer the track gain, if present. @item album Prefer the album gain, if present. @end table @item replaygain_preamp Pre-amplification gain in dB to apply to the selected replaygain gain. Default value for @var{replaygain_preamp} is 0.0. @item eval Set when the volume expression is evaluated. It accepts the following values: @table @samp @item once only evaluate expression once during the filter initialization, or when the @samp{volume} command is sent @item frame evaluate expression for each incoming frame @end table Default value is @samp{once}. @end table The volume expression can contain the following parameters. @table @option @item n frame number (starting at zero) @item nb_channels number of channels @item nb_consumed_samples number of samples consumed by the filter @item nb_samples number of samples in the current frame @item pos original frame position in the file @item pts frame PTS @item sample_rate sample rate @item startpts PTS at start of stream @item startt time at start of stream @item t frame time @item tb timestamp timebase @item volume last set volume value @end table Note that when @option{eval} is set to @samp{once} only the @var{sample_rate} and @var{tb} variables are available, all other variables will evaluate to NAN. @subsection Commands This filter supports the following commands: @table @option @item volume Modify the volume expression. The command accepts the same syntax of the corresponding option. If the specified expression is not valid, it is kept at its current value. @item replaygain_noclip Prevent clipping by limiting the gain applied. Default value for @var{replaygain_noclip} is 1. @end table @subsection Examples @itemize @item Halve the input audio volume: @example volume=volume=0.5 volume=volume=1/2 volume=volume=-6.0206dB @end example In all the above example the named key for @option{volume} can be omitted, for example like in: @example volume=0.5 @end example @item Increase input audio power by 6 decibels using fixed-point precision: @example volume=volume=6dB:precision=fixed @end example @item Fade volume after time 10 with an annihilation period of 5 seconds: @example volume='if(lt(t,10),1,max(1-(t-10)/5,0))':eval=frame @end example @end itemize @section volumedetect Detect the volume of the input video. The filter has no parameters. The input is not modified. Statistics about the volume will be printed in the log when the input stream end is reached. In particular it will show the mean volume (root mean square), maximum volume (on a per-sample basis), and the beginning of a histogram of the registered volume values (from the maximum value to a cumulated 1/1000 of the samples). All volumes are in decibels relative to the maximum PCM value. @subsection Examples Here is an excerpt of the output: @example [Parsed_volumedetect_0 @ 0xa23120] mean_volume: -27 dB [Parsed_volumedetect_0 @ 0xa23120] max_volume: -4 dB [Parsed_volumedetect_0 @ 0xa23120] histogram_4db: 6 [Parsed_volumedetect_0 @ 0xa23120] histogram_5db: 62 [Parsed_volumedetect_0 @ 0xa23120] histogram_6db: 286 [Parsed_volumedetect_0 @ 0xa23120] histogram_7db: 1042 [Parsed_volumedetect_0 @ 0xa23120] histogram_8db: 2551 [Parsed_volumedetect_0 @ 0xa23120] histogram_9db: 4609 [Parsed_volumedetect_0 @ 0xa23120] histogram_10db: 8409 @end example It means that: @itemize @item The mean square energy is approximately -27 dB, or 10^-2.7. @item The largest sample is at -4 dB, or more precisely between -4 dB and -5 dB. @item There are 6 samples at -4 dB, 62 at -5 dB, 286 at -6 dB, etc. @end itemize In other words, raising the volume by +4 dB does not cause any clipping, raising it by +5 dB causes clipping for 6 samples, etc. @c man end AUDIO FILTERS @chapter Audio Sources @c man begin AUDIO SOURCES Below is a description of the currently available audio sources. @section abuffer Buffer audio frames, and make them available to the filter chain. This source is mainly intended for a programmatic use, in particular through the interface defined in @file{libavfilter/asrc_abuffer.h}. It accepts the following parameters: @table @option @item time_base The timebase which will be used for timestamps of submitted frames. It must be either a floating-point number or in @var{numerator}/@var{denominator} form. @item sample_rate The sample rate of the incoming audio buffers. @item sample_fmt The sample format of the incoming audio buffers. Either a sample format name or its corresponging integer representation from the enum AVSampleFormat in @file{libavutil/samplefmt.h} @item channel_layout The channel layout of the incoming audio buffers. Either a channel layout name from channel_layout_map in @file{libavutil/channel_layout.c} or its corresponding integer representation from the AV_CH_LAYOUT_* macros in @file{libavutil/channel_layout.h} @item channels The number of channels of the incoming audio buffers. If both @var{channels} and @var{channel_layout} are specified, then they must be consistent. @end table @subsection Examples @example abuffer=sample_rate=44100:sample_fmt=s16p:channel_layout=stereo @end example will instruct the source to accept planar 16bit signed stereo at 44100Hz. Since the sample format with name "s16p" corresponds to the number 6 and the "stereo" channel layout corresponds to the value 0x3, this is equivalent to: @example abuffer=sample_rate=44100:sample_fmt=6:channel_layout=0x3 @end example @section aevalsrc Generate an audio signal specified by an expression. This source accepts in input one or more expressions (one for each channel), which are evaluated and used to generate a corresponding audio signal. This source accepts the following options: @table @option @item exprs Set the '|'-separated expressions list for each separate channel. In case the @option{channel_layout} option is not specified, the selected channel layout depends on the number of provided expressions. Otherwise the last specified expression is applied to the remaining output channels. @item channel_layout, c Set the channel layout. The number of channels in the specified layout must be equal to the number of specified expressions. @item duration, d Set the minimum duration of the sourced audio. See @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils} for the accepted syntax. Note that the resulting duration may be greater than the specified duration, as the generated audio is always cut at the end of a complete frame. If not specified, or the expressed duration is negative, the audio is supposed to be generated forever. @item nb_samples, n Set the number of samples per channel per each output frame, default to 1024. @item sample_rate, s Specify the sample rate, default to 44100. @end table Each expression in @var{exprs} can contain the following constants: @table @option @item n number of the evaluated sample, starting from 0 @item t time of the evaluated sample expressed in seconds, starting from 0 @item s sample rate @end table @subsection Examples @itemize @item Generate silence: @example aevalsrc=0 @end example @item Generate a sin signal with frequency of 440 Hz, set sample rate to 8000 Hz: @example aevalsrc="sin(440*2*PI*t):s=8000" @end example @item Generate a two channels signal, specify the channel layout (Front Center + Back Center) explicitly: @example aevalsrc="sin(420*2*PI*t)|cos(430*2*PI*t):c=FC|BC" @end example @item Generate white noise: @example aevalsrc="-2+random(0)" @end example @item Generate an amplitude modulated signal: @example aevalsrc="sin(10*2*PI*t)*sin(880*2*PI*t)" @end example @item Generate 2.5 Hz binaural beats on a 360 Hz carrier: @example aevalsrc="0.1*sin(2*PI*(360-2.5/2)*t) | 0.1*sin(2*PI*(360+2.5/2)*t)" @end example @end itemize @section anullsrc The null audio source, return unprocessed audio frames. It is mainly useful as a template and to be employed in analysis / debugging tools, or as the source for filters which ignore the input data (for example the sox synth filter). This source accepts the following options: @table @option @item channel_layout, cl Specifies the channel layout, and can be either an integer or a string representing a channel layout. The default value of @var{channel_layout} is "stereo". Check the channel_layout_map definition in @file{libavutil/channel_layout.c} for the mapping between strings and channel layout values. @item sample_rate, r Specifies the sample rate, and defaults to 44100. @item nb_samples, n Set the number of samples per requested frames. @end table @subsection Examples @itemize @item Set the sample rate to 48000 Hz and the channel layout to AV_CH_LAYOUT_MONO. @example anullsrc=r=48000:cl=4 @end example @item Do the same operation with a more obvious syntax: @example anullsrc=r=48000:cl=mono @end example @end itemize All the parameters need to be explicitly defined. @section flite Synthesize a voice utterance using the libflite library. To enable compilation of this filter you need to configure FFmpeg with @code{--enable-libflite}. Note that the flite library is not thread-safe. The filter accepts the following options: @table @option @item list_voices If set to 1, list the names of the available voices and exit immediately. Default value is 0. @item nb_samples, n Set the maximum number of samples per frame. Default value is 512. @item textfile Set the filename containing the text to speak. @item text Set the text to speak. @item voice, v Set the voice to use for the speech synthesis. Default value is @code{kal}. See also the @var{list_voices} option. @end table @subsection Examples @itemize @item Read from file @file{speech.txt}, and synthetize the text using the standard flite voice: @example flite=textfile=speech.txt @end example @item Read the specified text selecting the @code{slt} voice: @example flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt @end example @item Input text to ffmpeg: @example ffmpeg -f lavfi -i flite=text='So fare thee well, poor devil of a Sub-Sub, whose commentator I am':voice=slt @end example @item Make @file{ffplay} speak the specified text, using @code{flite} and the @code{lavfi} device: @example ffplay -f lavfi flite=text='No more be grieved for which that thou hast done.' @end example @end itemize For more information about libflite, check: @url{http://www.speech.cs.cmu.edu/flite/} @section sine Generate an audio signal made of a sine wave with amplitude 1/8. The audio signal is bit-exact. The filter accepts the following options: @table @option @item frequency, f Set the carrier frequency. Default is 440 Hz. @item beep_factor, b Enable a periodic beep every second with frequency @var{beep_factor} times the carrier frequency. Default is 0, meaning the beep is disabled. @item sample_rate, r Specify the sample rate, default is 44100. @item duration, d Specify the duration of the generated audio stream. @item samples_per_frame Set the number of samples per output frame, default is 1024. @end table @subsection Examples @itemize @item Generate a simple 440 Hz sine wave: @example sine @end example @item Generate a 220 Hz sine wave with a 880 Hz beep each second, for 5 seconds: @example sine=220:4:d=5 sine=f=220:b=4:d=5 sine=frequency=220:beep_factor=4:duration=5 @end example @end itemize @c man end AUDIO SOURCES @chapter Audio Sinks @c man begin AUDIO SINKS Below is a description of the currently available audio sinks. @section abuffersink Buffer audio frames, and make them available to the end of filter chain. This sink is mainly intended for programmatic use, in particular through the interface defined in @file{libavfilter/buffersink.h} or the options system. It accepts a pointer to an AVABufferSinkContext structure, which defines the incoming buffers' formats, to be passed as the opaque parameter to @code{avfilter_init_filter} for initialization. @section anullsink Null audio sink; do absolutely nothing with the input audio. It is mainly useful as a template and for use in analysis / debugging tools. @c man end AUDIO SINKS @chapter Video Filters @c man begin VIDEO FILTERS When you configure your FFmpeg build, you can disable any of the existing filters using @code{--disable-filters}. The configure output will show the video filters included in your build. Below is a description of the currently available video filters. @section alphaextract Extract the alpha component from the input as a grayscale video. This is especially useful with the @var{alphamerge} filter. @section alphamerge Add or replace the alpha component of the primary input with the grayscale value of a second input. This is intended for use with @var{alphaextract} to allow the transmission or storage of frame sequences that have alpha in a format that doesn't support an alpha channel. For example, to reconstruct full frames from a normal YUV-encoded video and a separate video created with @var{alphaextract}, you might use: @example movie=in_alpha.mkv [alpha]; [in][alpha] alphamerge [out] @end example Since this filter is designed for reconstruction, it operates on frame sequences without considering timestamps, and terminates when either input reaches end of stream. This will cause problems if your encoding pipeline drops frames. If you're trying to apply an image as an overlay to a video stream, consider the @var{overlay} filter instead. @section ass Same as the @ref{subtitles} filter, except that it doesn't require libavcodec and libavformat to work. On the other hand, it is limited to ASS (Advanced Substation Alpha) subtitles files. This filter accepts the following option in addition to the common options from the @ref{subtitles} filter: @table @option @item shaping Set the shaping engine Available values are: @table @samp @item auto The default libass shaping engine, which is the best available. @item simple Fast, font-agnostic shaper that can do only substitutions @item complex Slower shaper using OpenType for substitutions and positioning @end table The default is @code{auto}. @end table @section bbox Compute the bounding box for the non-black pixels in the input frame luminance plane. This filter computes the bounding box containing all the pixels with a luminance value greater than the minimum allowed value. The parameters describing the bounding box are printed on the filter log. The filter accepts the following option: @table @option @item min_val Set the minimal luminance value. Default is @code{16}. @end table @section blackdetect Detect video intervals that are (almost) completely black. Can be useful to detect chapter transitions, commercials, or invalid recordings. Output lines contains the time for the start, end and duration of the detected black interval expressed in seconds. In order to display the output lines, you need to set the loglevel at least to the AV_LOG_INFO value. The filter accepts the following options: @table @option @item black_min_duration, d Set the minimum detected black duration expressed in seconds. It must be a non-negative floating point number. Default value is 2.0. @item picture_black_ratio_th, pic_th Set the threshold for considering a picture "black". Express the minimum value for the ratio: @example @var{nb_black_pixels} / @var{nb_pixels} @end example for which a picture is considered black. Default value is 0.98. @item pixel_black_th, pix_th Set the threshold for considering a pixel "black". The threshold expresses the maximum pixel luminance value for which a pixel is considered "black". The provided value is scaled according to the following equation: @example @var{absolute_threshold} = @var{luminance_minimum_value} + @var{pixel_black_th} * @var{luminance_range_size} @end example @var{luminance_range_size} and @var{luminance_minimum_value} depend on the input video format, the range is [0-255] for YUV full-range formats and [16-235] for YUV non full-range formats. Default value is 0.10. @end table The following example sets the maximum pixel threshold to the minimum value, and detects only black intervals of 2 or more seconds: @example blackdetect=d=2:pix_th=0.00 @end example @section blackframe Detect frames that are (almost) completely black. Can be useful to detect chapter transitions or commercials. Output lines consist of the frame number of the detected frame, the percentage of blackness, the position in the file if known or -1 and the timestamp in seconds. In order to display the output lines, you need to set the loglevel at least to the AV_LOG_INFO value. It accepts the following parameters: @table @option @item amount The percentage of the pixels that have to be below the threshold; it defaults to @code{98}. @item threshold, thresh The threshold below which a pixel value is considered black; it defaults to @code{32}. @end table @section blend Blend two video frames into each other. It takes two input streams and outputs one stream, the first input is the "top" layer and second input is "bottom" layer. Output terminates when shortest input terminates. A description of the accepted options follows. @table @option @item c0_mode @item c1_mode @item c2_mode @item c3_mode @item all_mode Set blend mode for specific pixel component or all pixel components in case of @var{all_mode}. Default value is @code{normal}. Available values for component modes are: @table @samp @item addition @item and @item average @item burn @item darken @item difference @item divide @item dodge @item exclusion @item hardlight @item lighten @item multiply @item negation @item normal @item or @item overlay @item phoenix @item pinlight @item reflect @item screen @item softlight @item subtract @item vividlight @item xor @end table @item c0_opacity @item c1_opacity @item c2_opacity @item c3_opacity @item all_opacity Set blend opacity for specific pixel component or all pixel components in case of @var{all_opacity}. Only used in combination with pixel component blend modes. @item c0_expr @item c1_expr @item c2_expr @item c3_expr @item all_expr Set blend expression for specific pixel component or all pixel components in case of @var{all_expr}. Note that related mode options will be ignored if those are set. The expressions can use the following variables: @table @option @item N The sequential number of the filtered frame, starting from @code{0}. @item X @item Y the coordinates of the current sample @item W @item H the width and height of currently filtered plane @item SW @item SH Width and height scale depending on the currently filtered plane. It is the ratio between the corresponding luma plane number of pixels and the current plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and @code{0.5,0.5} for chroma planes. @item T Time of the current frame, expressed in seconds. @item TOP, A Value of pixel component at current location for first video frame (top layer). @item BOTTOM, B Value of pixel component at current location for second video frame (bottom layer). @end table @item shortest Force termination when the shortest input terminates. Default is @code{0}. @item repeatlast Continue applying the last bottom frame after the end of the stream. A value of @code{0} disable the filter after the last frame of the bottom layer is reached. Default is @code{1}. @end table @subsection Examples @itemize @item Apply transition from bottom layer to top layer in first 10 seconds: @example blend=all_expr='A*(if(gte(T,10),1,T/10))+B*(1-(if(gte(T,10),1,T/10)))' @end example @item Apply 1x1 checkerboard effect: @example blend=all_expr='if(eq(mod(X,2),mod(Y,2)),A,B)' @end example @item Apply uncover left effect: @example blend=all_expr='if(gte(N*SW+X,W),A,B)' @end example @item Apply uncover down effect: @example blend=all_expr='if(gte(Y-N*SH,0),A,B)' @end example @item Apply uncover up-left effect: @example blend=all_expr='if(gte(T*SH*40+Y,H)*gte((T*40*SW+X)*W/H,W),A,B)' @end example @end itemize @section boxblur Apply a boxblur algorithm to the input video. It accepts the following parameters: @table @option @item luma_radius, lr @item luma_power, lp @item chroma_radius, cr @item chroma_power, cp @item alpha_radius, ar @item alpha_power, ap @end table A description of the accepted options follows. @table @option @item luma_radius, lr @item chroma_radius, cr @item alpha_radius, ar Set an expression for the box radius in pixels used for blurring the corresponding input plane. The radius value must be a non-negative number, and must not be greater than the value of the expression @code{min(w,h)/2} for the luma and alpha planes, and of @code{min(cw,ch)/2} for the chroma planes. Default value for @option{luma_radius} is "2". If not specified, @option{chroma_radius} and @option{alpha_radius} default to the corresponding value set for @option{luma_radius}. The expressions can contain the following constants: @table @option @item w @item h The input width and height in pixels. @item cw @item ch The input chroma image width and height in pixels. @item hsub @item vsub The horizontal and vertical chroma subsample values. For example, for the pixel format "yuv422p", @var{hsub} is 2 and @var{vsub} is 1. @end table @item luma_power, lp @item chroma_power, cp @item alpha_power, ap Specify how many times the boxblur filter is applied to the corresponding plane. Default value for @option{luma_power} is 2. If not specified, @option{chroma_power} and @option{alpha_power} default to the corresponding value set for @option{luma_power}. A value of 0 will disable the effect. @end table @subsection Examples @itemize @item Apply a boxblur filter with the luma, chroma, and alpha radii set to 2: @example boxblur=luma_radius=2:luma_power=1 boxblur=2:1 @end example @item Set the luma radius to 2, and alpha and chroma radius to 0: @example boxblur=2:1:cr=0:ar=0 @end example @item Set the luma and chroma radii to a fraction of the video dimension: @example boxblur=luma_radius=min(h\,w)/10:luma_power=1:chroma_radius=min(cw\,ch)/10:chroma_power=1 @end example @end itemize @section codecview Visualize information exported by some codecs. Some codecs can export information through frames using side-data or other means. For example, some MPEG based codecs export motion vectors through the @var{export_mvs} flag in the codec @option{flags2} option. The filter accepts the following option: @table @option @item mv Set motion vectors to visualize. Available flags for @var{mv} are: @table @samp @item pf forward predicted MVs of P-frames @item bf forward predicted MVs of B-frames @item bb backward predicted MVs of B-frames @end table @end table @subsection Examples @itemize @item Visualizes multi-directionals MVs from P and B-Frames using @command{ffplay}: @example ffplay -flags2 +export_mvs input.mpg -vf codecview=mv=pf+bf+bb @end example @end itemize @section colorbalance Modify intensity of primary colors (red, green and blue) of input frames. The filter allows an input frame to be adjusted in the shadows, midtones or highlights regions for the red-cyan, green-magenta or blue-yellow balance. A positive adjustment value shifts the balance towards the primary color, a negative value towards the complementary color. The filter accepts the following options: @table @option @item rs @item gs @item bs Adjust red, green and blue shadows (darkest pixels). @item rm @item gm @item bm Adjust red, green and blue midtones (medium pixels). @item rh @item gh @item bh Adjust red, green and blue highlights (brightest pixels). Allowed ranges for options are @code{[-1.0, 1.0]}. Defaults are @code{0}. @end table @subsection Examples @itemize @item Add red color cast to shadows: @example colorbalance=rs=.3 @end example @end itemize @section colorchannelmixer Adjust video input frames by re-mixing color channels. This filter modifies a color channel by adding the values associated to the other channels of the same pixels. For example if the value to modify is red, the output value will be: @example @var{red}=@var{red}*@var{rr} + @var{blue}*@var{rb} + @var{green}*@var{rg} + @var{alpha}*@var{ra} @end example The filter accepts the following options: @table @option @item rr @item rg @item rb @item ra Adjust contribution of input red, green, blue and alpha channels for output red channel. Default is @code{1} for @var{rr}, and @code{0} for @var{rg}, @var{rb} and @var{ra}. @item gr @item gg @item gb @item ga Adjust contribution of input red, green, blue and alpha channels for output green channel. Default is @code{1} for @var{gg}, and @code{0} for @var{gr}, @var{gb} and @var{ga}. @item br @item bg @item bb @item ba Adjust contribution of input red, green, blue and alpha channels for output blue channel. Default is @code{1} for @var{bb}, and @code{0} for @var{br}, @var{bg} and @var{ba}. @item ar @item ag @item ab @item aa Adjust contribution of input red, green, blue and alpha channels for output alpha channel. Default is @code{1} for @var{aa}, and @code{0} for @var{ar}, @var{ag} and @var{ab}. Allowed ranges for options are @code{[-2.0, 2.0]}. @end table @subsection Examples @itemize @item Convert source to grayscale: @example colorchannelmixer=.3:.4:.3:0:.3:.4:.3:0:.3:.4:.3 @end example @item Simulate sepia tones: @example colorchannelmixer=.393:.769:.189:0:.349:.686:.168:0:.272:.534:.131 @end example @end itemize @section colormatrix Convert color matrix. The filter accepts the following options: @table @option @item src @item dst Specify the source and destination color matrix. Both values must be specified. The accepted values are: @table @samp @item bt709 BT.709 @item bt601 BT.601 @item smpte240m SMPTE-240M @item fcc FCC @end table @end table For example to convert from BT.601 to SMPTE-240M, use the command: @example colormatrix=bt601:smpte240m @end example @section copy Copy the input source unchanged to the output. This is mainly useful for testing purposes. @section crop Crop the input video to given dimensions. It accepts the following parameters: @table @option @item w, out_w The width of the output video. It defaults to @code{iw}. This expression is evaluated only once during the filter configuration. @item h, out_h The height of the output video. It defaults to @code{ih}. This expression is evaluated only once during the filter configuration. @item x The horizontal position, in the input video, of the left edge of the output video. It defaults to @code{(in_w-out_w)/2}. This expression is evaluated per-frame. @item y The vertical position, in the input video, of the top edge of the output video. It defaults to @code{(in_h-out_h)/2}. This expression is evaluated per-frame. @item keep_aspect If set to 1 will force the output display aspect ratio to be the same of the input, by changing the output sample aspect ratio. It defaults to 0. @end table The @var{out_w}, @var{out_h}, @var{x}, @var{y} parameters are expressions containing the following constants: @table @option @item x @item y The computed values for @var{x} and @var{y}. They are evaluated for each new frame. @item in_w @item in_h The input width and height. @item iw @item ih These are the same as @var{in_w} and @var{in_h}. @item out_w @item out_h The output (cropped) width and height. @item ow @item oh These are the same as @var{out_w} and @var{out_h}. @item a same as @var{iw} / @var{ih} @item sar input sample aspect ratio @item dar input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar} @item hsub @item vsub horizontal and vertical chroma subsample values. For example for the pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. @item n The number of the input frame, starting from 0. @item pos the position in the file of the input frame, NAN if unknown @item t The timestamp expressed in seconds. It's NAN if the input timestamp is unknown. @end table The expression for @var{out_w} may depend on the value of @var{out_h}, and the expression for @var{out_h} may depend on @var{out_w}, but they cannot depend on @var{x} and @var{y}, as @var{x} and @var{y} are evaluated after @var{out_w} and @var{out_h}. The @var{x} and @var{y} parameters specify the expressions for the position of the top-left corner of the output (non-cropped) area. They are evaluated for each frame. If the evaluated value is not valid, it is approximated to the nearest valid value. The expression for @var{x} may depend on @var{y}, and the expression for @var{y} may depend on @var{x}. @subsection Examples @itemize @item Crop area with size 100x100 at position (12,34). @example crop=100:100:12:34 @end example Using named options, the example above becomes: @example crop=w=100:h=100:x=12:y=34 @end example @item Crop the central input area with size 100x100: @example crop=100:100 @end example @item Crop the central input area with size 2/3 of the input video: @example crop=2/3*in_w:2/3*in_h @end example @item Crop the input video central square: @example crop=out_w=in_h crop=in_h @end example @item Delimit the rectangle with the top-left corner placed at position 100:100 and the right-bottom corner corresponding to the right-bottom corner of the input image. @example crop=in_w-100:in_h-100:100:100 @end example @item Crop 10 pixels from the left and right borders, and 20 pixels from the top and bottom borders @example crop=in_w-2*10:in_h-2*20 @end example @item Keep only the bottom right quarter of the input image: @example crop=in_w/2:in_h/2:in_w/2:in_h/2 @end example @item Crop height for getting Greek harmony: @example crop=in_w:1/PHI*in_w @end example @item Appply trembling effect: @example crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7) @end example @item Apply erratic camera effect depending on timestamp: @example crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)" @end example @item Set x depending on the value of y: @example crop=in_w/2:in_h/2:y:10+10*sin(n/10) @end example @end itemize @section cropdetect Auto-detect the crop size. It calculates the necessary cropping parameters and prints the recommended parameters via the logging system. The detected dimensions correspond to the non-black area of the input video. It accepts the following parameters: @table @option @item limit Set higher black value threshold, which can be optionally specified from nothing (0) to everything (255). An intensity value greater to the set value is considered non-black. It defaults to 24. @item round The value which the width/height should be divisible by. It defaults to 16. The offset is automatically adjusted to center the video. Use 2 to get only even dimensions (needed for 4:2:2 video). 16 is best when encoding to most video codecs. @item reset_count, reset Set the counter that determines after how many frames cropdetect will reset the previously detected largest video area and start over to detect the current optimal crop area. Default value is 0. This can be useful when channel logos distort the video area. 0 indicates 'never reset', and returns the largest area encountered during playback. @end table @anchor{curves} @section curves Apply color adjustments using curves. This filter is similar to the Adobe Photoshop and GIMP curves tools. Each component (red, green and blue) has its values defined by @var{N} key points tied from each other using a smooth curve. The x-axis represents the pixel values from the input frame, and the y-axis the new pixel values to be set for the output frame. By default, a component curve is defined by the two points @var{(0;0)} and @var{(1;1)}. This creates a straight line where each original pixel value is "adjusted" to its own value, which means no change to the image. The filter allows you to redefine these two points and add some more. A new curve (using a natural cubic spline interpolation) will be define to pass smoothly through all these new coordinates. The new defined points needs to be strictly increasing over the x-axis, and their @var{x} and @var{y} values must be in the @var{[0;1]} interval. If the computed curves happened to go outside the vector spaces, the values will be clipped accordingly. If there is no key point defined in @code{x=0}, the filter will automatically insert a @var{(0;0)} point. In the same way, if there is no key point defined in @code{x=1}, the filter will automatically insert a @var{(1;1)} point. The filter accepts the following options: @table @option @item preset Select one of the available color presets. This option can be used in addition to the @option{r}, @option{g}, @option{b} parameters; in this case, the later options takes priority on the preset values. Available presets are: @table @samp @item none @item color_negative @item cross_process @item darker @item increase_contrast @item lighter @item linear_contrast @item medium_contrast @item negative @item strong_contrast @item vintage @end table Default is @code{none}. @item master, m Set the master key points. These points will define a second pass mapping. It is sometimes called a "luminance" or "value" mapping. It can be used with @option{r}, @option{g}, @option{b} or @option{all} since it acts like a post-processing LUT. @item red, r Set the key points for the red component. @item green, g Set the key points for the green component. @item blue, b Set the key points for the blue component. @item all Set the key points for all components (not including master). Can be used in addition to the other key points component options. In this case, the unset component(s) will fallback on this @option{all} setting. @item psfile Specify a Photoshop curves file (@code{.asv}) to import the settings from. @end table To avoid some filtergraph syntax conflicts, each key points list need to be defined using the following syntax: @code{x0/y0 x1/y1 x2/y2 ...}. @subsection Examples @itemize @item Increase slightly the middle level of blue: @example curves=blue='0.5/0.58' @end example @item Vintage effect: @example curves=r='0/0.11 .42/.51 1/0.95':g='0.50/0.48':b='0/0.22 .49/.44 1/0.8' @end example Here we obtain the following coordinates for each components: @table @var @item red @code{(0;0.11) (0.42;0.51) (1;0.95)} @item green @code{(0;0) (0.50;0.48) (1;1)} @item blue @code{(0;0.22) (0.49;0.44) (1;0.80)} @end table @item The previous example can also be achieved with the associated built-in preset: @example curves=preset=vintage @end example @item Or simply: @example curves=vintage @end example @item Use a Photoshop preset and redefine the points of the green component: @example curves=psfile='MyCurvesPresets/purple.asv':green='0.45/0.53' @end example @end itemize @section dctdnoiz Denoise frames using 2D DCT (frequency domain filtering). This filter is not designed for real time. The filter accepts the following options: @table @option @item sigma, s Set the noise sigma constant. This @var{sigma} defines a hard threshold of @code{3 * sigma}; every DCT coefficient (absolute value) below this threshold with be dropped. If you need a more advanced filtering, see @option{expr}. Default is @code{0}. @item overlap Set number overlapping pixels for each block. Since the filter can be slow, you may want to reduce this value, at the cost of a less effective filter and the risk of various artefacts. If the overlapping value doesn't permit processing the whole input width or height, a warning will be displayed and according borders won't be denoised. Default value is @var{blocksize}-1, which is the best possible setting. @item expr, e Set the coefficient factor expression. For each coefficient of a DCT block, this expression will be evaluated as a multiplier value for the coefficient. If this is option is set, the @option{sigma} option will be ignored. The absolute value of the coefficient can be accessed through the @var{c} variable. @item n Set the @var{blocksize} using the number of bits. @code{1<<@var{n}} defines the @var{blocksize}, which is the width and height of the processed blocks. The default value is @var{3} (8x8) and can be raised to @var{4} for a @var{blocksize} of 16x16. Note that changing this setting has huge consequences on the speed processing. Also, a larger block size does not necessarily means a better de-noising. @end table @subsection Examples Apply a denoise with a @option{sigma} of @code{4.5}: @example dctdnoiz=4.5 @end example The same operation can be achieved using the expression system: @example dctdnoiz=e='gte(c, 4.5*3)' @end example Violent denoise using a block size of @code{16x16}: @example dctdnoiz=15:n=4 @end example @anchor{decimate} @section decimate Drop duplicated frames at regular intervals. The filter accepts the following options: @table @option @item cycle Set the number of frames from which one will be dropped. Setting this to @var{N} means one frame in every batch of @var{N} frames will be dropped. Default is @code{5}. @item dupthresh Set the threshold for duplicate detection. If the difference metric for a frame is less than or equal to this value, then it is declared as duplicate. Default is @code{1.1} @item scthresh Set scene change threshold. Default is @code{15}. @item blockx @item blocky Set the size of the x and y-axis blocks used during metric calculations. Larger blocks give better noise suppression, but also give worse detection of small movements. Must be a power of two. Default is @code{32}. @item ppsrc Mark main input as a pre-processed input and activate clean source input stream. This allows the input to be pre-processed with various filters to help the metrics calculation while keeping the frame selection lossless. When set to @code{1}, the first stream is for the pre-processed input, and the second stream is the clean source from where the kept frames are chosen. Default is @code{0}. @item chroma Set whether or not chroma is considered in the metric calculations. Default is @code{1}. @end table @section dejudder Remove judder produced by partially interlaced telecined content. Judder can be introduced, for instance, by @ref{pullup} filter. If the original source was partially telecined content then the output of @code{pullup,dejudder} will have a variable frame rate. May change the recorded frame rate of the container. Aside from that change, this filter will not affect constant frame rate video. The option available in this filter is: @table @option @item cycle Specify the length of the window over which the judder repeats. Accepts any integer greater than 1. Useful values are: @table @samp @item 4 If the original was telecined from 24 to 30 fps (Film to NTSC). @item 5 If the original was telecined from 25 to 30 fps (PAL to NTSC). @item 20 If a mixture of the two. @end table The default is @samp{4}. @end table @section delogo Suppress a TV station logo by a simple interpolation of the surrounding pixels. Just set a rectangle covering the logo and watch it disappear (and sometimes something even uglier appear - your mileage may vary). It accepts the following parameters: @table @option @item x @item y Specify the top left corner coordinates of the logo. They must be specified. @item w @item h Specify the width and height of the logo to clear. They must be specified. @item band, t Specify the thickness of the fuzzy edge of the rectangle (added to @var{w} and @var{h}). The default value is 4. @item show When set to 1, a green rectangle is drawn on the screen to simplify finding the right @var{x}, @var{y}, @var{w}, and @var{h} parameters. The default value is 0. The rectangle is drawn on the outermost pixels which will be (partly) replaced with interpolated values. The values of the next pixels immediately outside this rectangle in each direction will be used to compute the interpolated pixel values inside the rectangle. @end table @subsection Examples @itemize @item Set a rectangle covering the area with top left corner coordinates 0,0 and size 100x77, and a band of size 10: @example delogo=x=0:y=0:w=100:h=77:band=10 @end example @end itemize @section deshake Attempt to fix small changes in horizontal and/or vertical shift. This filter helps remove camera shake from hand-holding a camera, bumping a tripod, moving on a vehicle, etc. The filter accepts the following options: @table @option @item x @item y @item w @item h Specify a rectangular area where to limit the search for motion vectors. If desired the search for motion vectors can be limited to a rectangular area of the frame defined by its top left corner, width and height. These parameters have the same meaning as the drawbox filter which can be used to visualise the position of the bounding box. This is useful when simultaneous movement of subjects within the frame might be confused for camera motion by the motion vector search. If any or all of @var{x}, @var{y}, @var{w} and @var{h} are set to -1 then the full frame is used. This allows later options to be set without specifying the bounding box for the motion vector search. Default - search the whole frame. @item rx @item ry Specify the maximum extent of movement in x and y directions in the range 0-64 pixels. Default 16. @item edge Specify how to generate pixels to fill blanks at the edge of the frame. Available values are: @table @samp @item blank, 0 Fill zeroes at blank locations @item original, 1 Original image at blank locations @item clamp, 2 Extruded edge value at blank locations @item mirror, 3 Mirrored edge at blank locations @end table Default value is @samp{mirror}. @item blocksize Specify the blocksize to use for motion search. Range 4-128 pixels, default 8. @item contrast Specify the contrast threshold for blocks. Only blocks with more than the specified contrast (difference between darkest and lightest pixels) will be considered. Range 1-255, default 125. @item search Specify the search strategy. Available values are: @table @samp @item exhaustive, 0 Set exhaustive search @item less, 1 Set less exhaustive search. @end table Default value is @samp{exhaustive}. @item filename If set then a detailed log of the motion search is written to the specified file. @item opencl If set to 1, specify using OpenCL capabilities, only available if FFmpeg was configured with @code{--enable-opencl}. Default value is 0. @end table @section drawbox Draw a colored box on the input image. It accepts the following parameters: @table @option @item x @item y The expressions which specify the top left corner coordinates of the box. It defaults to 0. @item width, w @item height, h The expressions which specify the width and height of the box; if 0 they are interpreted as the input width and height. It defaults to 0. @item color, c Specify the color of the box to write. For the general syntax of this option, check the "Color" section in the ffmpeg-utils manual. If the special value @code{invert} is used, the box edge color is the same as the video with inverted luma. @item thickness, t The expression which sets the thickness of the box edge. Default value is @code{3}. See below for the list of accepted constants. @end table The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the following constants: @table @option @item dar The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}. @item hsub @item vsub horizontal and vertical chroma subsample values. For example for the pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. @item in_h, ih @item in_w, iw The input width and height. @item sar The input sample aspect ratio. @item x @item y The x and y offset coordinates where the box is drawn. @item w @item h The width and height of the drawn box. @item t The thickness of the drawn box. These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}. @end table @subsection Examples @itemize @item Draw a black box around the edge of the input image: @example drawbox @end example @item Draw a box with color red and an opacity of 50%: @example drawbox=10:20:200:60:red@@0.5 @end example The previous example can be specified as: @example drawbox=x=10:y=20:w=200:h=60:color=red@@0.5 @end example @item Fill the box with pink color: @example drawbox=x=10:y=10:w=100:h=100:color=pink@@0.5:t=max @end example @item Draw a 2-pixel red 2.40:1 mask: @example drawbox=x=-t:y=0.5*(ih-iw/2.4)-t:w=iw+t*2:h=iw/2.4+t*2:t=2:c=red @end example @end itemize @section drawgrid Draw a grid on the input image. It accepts the following parameters: @table @option @item x @item y The expressions which specify the coordinates of some point of grid intersection (meant to configure offset). Both default to 0. @item width, w @item height, h The expressions which specify the width and height of the grid cell, if 0 they are interpreted as the input width and height, respectively, minus @code{thickness}, so image gets framed. Default to 0. @item color, c Specify the color of the grid. For the general syntax of this option, check the "Color" section in the ffmpeg-utils manual. If the special value @code{invert} is used, the grid color is the same as the video with inverted luma. @item thickness, t The expression which sets the thickness of the grid line. Default value is @code{1}. See below for the list of accepted constants. @end table The parameters for @var{x}, @var{y}, @var{w} and @var{h} and @var{t} are expressions containing the following constants: @table @option @item dar The input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar}. @item hsub @item vsub horizontal and vertical chroma subsample values. For example for the pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. @item in_h, ih @item in_w, iw The input grid cell width and height. @item sar The input sample aspect ratio. @item x @item y The x and y coordinates of some point of grid intersection (meant to configure offset). @item w @item h The width and height of the drawn cell. @item t The thickness of the drawn cell. These constants allow the @var{x}, @var{y}, @var{w}, @var{h} and @var{t} expressions to refer to each other, so you may for example specify @code{y=x/dar} or @code{h=w/dar}. @end table @subsection Examples @itemize @item Draw a grid with cell 100x100 pixels, thickness 2 pixels, with color red and an opacity of 50%: @example drawgrid=width=100:height=100:thickness=2:color=red@@0.5 @end example @item Draw a white 3x3 grid with an opacity of 50%: @example drawgrid=w=iw/3:h=ih/3:t=2:c=white@@0.5 @end example @end itemize @anchor{drawtext} @section drawtext Draw a text string or text from a specified file on top of a video, using the libfreetype library. To enable compilation of this filter, you need to configure FFmpeg with @code{--enable-libfreetype}. To enable default font fallback and the @var{font} option you need to configure FFmpeg with @code{--enable-libfontconfig}. To enable the @var{text_shaping} option, you need to configure FFmpeg with @code{--enable-libfribidi}. @subsection Syntax It accepts the following parameters: @table @option @item box Used to draw a box around text using the background color. The value must be either 1 (enable) or 0 (disable). The default value of @var{box} is 0. @item boxcolor The color to be used for drawing box around text. For the syntax of this option, check the "Color" section in the ffmpeg-utils manual. The default value of @var{boxcolor} is "white". @item borderw Set the width of the border to be drawn around the text using @var{bordercolor}. The default value of @var{borderw} is 0. @item bordercolor Set the color to be used for drawing border around text. For the syntax of this option, check the "Color" section in the ffmpeg-utils manual. The default value of @var{bordercolor} is "black". @item expansion Select how the @var{text} is expanded. Can be either @code{none}, @code{strftime} (deprecated) or @code{normal} (default). See the @ref{drawtext_expansion, Text expansion} section below for details. @item fix_bounds If true, check and fix text coords to avoid clipping. @item fontcolor The color to be used for drawing fonts. For the syntax of this option, check the "Color" section in the ffmpeg-utils manual. The default value of @var{fontcolor} is "black". @item fontcolor_expr String which is expanded the same way as @var{text} to obtain dynamic @var{fontcolor} value. By default this option has empty value and is not processed. When this option is set, it overrides @var{fontcolor} option. @item font The font family to be used for drawing text. By default Sans. @item fontfile The font file to be used for drawing text. The path must be included. This parameter is mandatory if the fontconfig support is disabled. @item fontsize The font size to be used for drawing text. The default value of @var{fontsize} is 16. @item text_shaping If set to 1, attempt to shape the text (for example, reverse the order of right-to-left text and join Arabic characters) before drawing it. Otherwise, just draw the text exactly as given. By default 1 (if supported). @item ft_load_flags The flags to be used for loading the fonts. The flags map the corresponding flags supported by libfreetype, and are a combination of the following values: @table @var @item default @item no_scale @item no_hinting @item render @item no_bitmap @item vertical_layout @item force_autohint @item crop_bitmap @item pedantic @item ignore_global_advance_width @item no_recurse @item ignore_transform @item monochrome @item linear_design @item no_autohint @end table Default value is "default". For more information consult the documentation for the FT_LOAD_* libfreetype flags. @item shadowcolor The color to be used for drawing a shadow behind the drawn text. For the syntax of this option, check the "Color" section in the ffmpeg-utils manual. The default value of @var{shadowcolor} is "black". @item shadowx @item shadowy The x and y offsets for the text shadow position with respect to the position of the text. They can be either positive or negative values. The default value for both is "0". @item start_number The starting frame number for the n/frame_num variable. The default value is "0". @item tabsize The size in number of spaces to use for rendering the tab. Default value is 4. @item timecode Set the initial timecode representation in "hh:mm:ss[:;.]ff" format. It can be used with or without text parameter. @var{timecode_rate} option must be specified. @item timecode_rate, rate, r Set the timecode frame rate (timecode only). @item text The text string to be drawn. The text must be a sequence of UTF-8 encoded characters. This parameter is mandatory if no file is specified with the parameter @var{textfile}. @item textfile A text file containing text to be drawn. The text must be a sequence of UTF-8 encoded characters. This parameter is mandatory if no text string is specified with the parameter @var{text}. If both @var{text} and @var{textfile} are specified, an error is thrown. @item reload If set to 1, the @var{textfile} will be reloaded before each frame. Be sure to update it atomically, or it may be read partially, or even fail. @item x @item y The expressions which specify the offsets where text will be drawn within the video frame. They are relative to the top/left border of the output image. The default value of @var{x} and @var{y} is "0". See below for the list of accepted constants and functions. @end table The parameters for @var{x} and @var{y} are expressions containing the following constants and functions: @table @option @item dar input display aspect ratio, it is the same as (@var{w} / @var{h}) * @var{sar} @item hsub @item vsub horizontal and vertical chroma subsample values. For example for the pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. @item line_h, lh the height of each text line @item main_h, h, H the input height @item main_w, w, W the input width @item max_glyph_a, ascent the maximum distance from the baseline to the highest/upper grid coordinate used to place a glyph outline point, for all the rendered glyphs. It is a positive value, due to the grid's orientation with the Y axis upwards. @item max_glyph_d, descent the maximum distance from the baseline to the lowest grid coordinate used to place a glyph outline point, for all the rendered glyphs. This is a negative value, due to the grid's orientation, with the Y axis upwards. @item max_glyph_h maximum glyph height, that is the maximum height for all the glyphs contained in the rendered text, it is equivalent to @var{ascent} - @var{descent}. @item max_glyph_w maximum glyph width, that is the maximum width for all the glyphs contained in the rendered text @item n the number of input frame, starting from 0 @item rand(min, max) return a random number included between @var{min} and @var{max} @item sar The input sample aspect ratio. @item t timestamp expressed in seconds, NAN if the input timestamp is unknown @item text_h, th the height of the rendered text @item text_w, tw the width of the rendered text @item x @item y the x and y offset coordinates where the text is drawn. These parameters allow the @var{x} and @var{y} expressions to refer each other, so you can for example specify @code{y=x/dar}. @end table @anchor{drawtext_expansion} @subsection Text expansion If @option{expansion} is set to @code{strftime}, the filter recognizes strftime() sequences in the provided text and expands them accordingly. Check the documentation of strftime(). This feature is deprecated. If @option{expansion} is set to @code{none}, the text is printed verbatim. If @option{expansion} is set to @code{normal} (which is the default), the following expansion mechanism is used. The backslash character '\', followed by any character, always expands to the second character. Sequence of the form @code{%@{...@}} are expanded. The text between the braces is a function name, possibly followed by arguments separated by ':'. If the arguments contain special characters or delimiters (':' or '@}'), they should be escaped. Note that they probably must also be escaped as the value for the @option{text} option in the filter argument string and as the filter argument in the filtergraph description, and possibly also for the shell, that makes up to four levels of escaping; using a text file avoids these problems. The following functions are available: @table @command @item expr, e The expression evaluation result. It must take one argument specifying the expression to be evaluated, which accepts the same constants and functions as the @var{x} and @var{y} values. Note that not all constants should be used, for example the text size is not known when evaluating the expression, so the constants @var{text_w} and @var{text_h} will have an undefined value. @item expr_int_format, eif Evaluate the expression's value and output as formatted integer. The first argument is the expression to be evaluated, just as for the @var{expr} function. The second argument specifies the output format. Allowed values are 'x', 'X', 'd' and 'u'. They are treated exactly as in the printf function. The third parameter is optional and sets the number of positions taken by the output. It can be used to add padding with zeros from the left. @item gmtime The time at which the filter is running, expressed in UTC. It can accept an argument: a strftime() format string. @item localtime The time at which the filter is running, expressed in the local time zone. It can accept an argument: a strftime() format string. @item metadata Frame metadata. It must take one argument specifying metadata key. @item n, frame_num The frame number, starting from 0. @item pict_type A 1 character description of the current picture type. @item pts The timestamp of the current frame. It can take up to two arguments. The first argument is the format of the timestamp; it defaults to @code{flt} for seconds as a decimal number with microsecond accuracy; @code{hms} stands for a formatted @var{[-]HH:MM:SS.mmm} timestamp with millisecond accuracy. The second argument is an offset added to the timestamp. @end table @subsection Examples @itemize @item Draw "Test Text" with font FreeSerif, using the default values for the optional parameters. @example drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'" @end example @item Draw 'Test Text' with font FreeSerif of size 24 at position x=100 and y=50 (counting from the top-left corner of the screen), text is yellow with a red box around it. Both the text and the box have an opacity of 20%. @example drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\ x=100: y=50: fontsize=24: fontcolor=yellow@@0.2: box=1: boxcolor=red@@0.2" @end example Note that the double quotes are not necessary if spaces are not used within the parameter list. @item Show the text at the center of the video frame: @example drawtext="fontsize=30:fontfile=FreeSerif.ttf:text='hello world':x=(w-text_w)/2:y=(h-text_h)/2" @end example @item Show a text line sliding from right to left in the last row of the video frame. The file @file{LONG_LINE} is assumed to contain a single line with no newlines. @example drawtext="fontsize=15:fontfile=FreeSerif.ttf:text=LONG_LINE:y=h-line_h:x=-50*t" @end example @item Show the content of file @file{CREDITS} off the bottom of the frame and scroll up. @example drawtext="fontsize=20:fontfile=FreeSerif.ttf:textfile=CREDITS:y=h-20*t" @end example @item Draw a single green letter "g", at the center of the input video. The glyph baseline is placed at half screen height. @example drawtext="fontsize=60:fontfile=FreeSerif.ttf:fontcolor=green:text=g:x=(w-max_glyph_w)/2:y=h/2-ascent" @end example @item Show text for 1 second every 3 seconds: @example drawtext="fontfile=FreeSerif.ttf:fontcolor=white:x=100:y=x/dar:enable=lt(mod(t\,3)\,1):text='blink'" @end example @item Use fontconfig to set the font. Note that the colons need to be escaped. @example drawtext='fontfile=Linux Libertine O-40\:style=Semibold:text=FFmpeg' @end example @item Print the date of a real-time encoding (see strftime(3)): @example drawtext='fontfile=FreeSans.ttf:text=%@{localtime\:%a %b %d %Y@}' @end example @item Show text fading in and out (appearing/disappearing): @example #!/bin/sh DS=1.0 # display start DE=10.0 # display end FID=1.5 # fade in duration FOD=5 # fade out duration ffplay -f lavfi "color,drawtext=text=TEST:fontsize=50:fontfile=FreeSerif.ttf:fontcolor_expr=ff0000%@{eif\\\\: clip(255*(1*between(t\\, $DS + $FID\\, $DE - $FOD) + ((t - $DS)/$FID)*between(t\\, $DS\\, $DS + $FID) + (-(t - $DE)/$FOD)*between(t\\, $DE - $FOD\\, $DE) )\\, 0\\, 255) \\\\: x\\\\: 2 @}" @end example @end itemize For more information about libfreetype, check: @url{http://www.freetype.org/}. For more information about fontconfig, check: @url{http://freedesktop.org/software/fontconfig/fontconfig-user.html}. For more information about libfribidi, check: @url{http://fribidi.org/}. @section edgedetect Detect and draw edges. The filter uses the Canny Edge Detection algorithm. The filter accepts the following options: @table @option @item low @item high Set low and high threshold values used by the Canny thresholding algorithm. The high threshold selects the "strong" edge pixels, which are then connected through 8-connectivity with the "weak" edge pixels selected by the low threshold. @var{low} and @var{high} threshold values must be chosen in the range [0,1], and @var{low} should be lesser or equal to @var{high}. Default value for @var{low} is @code{20/255}, and default value for @var{high} is @code{50/255}. @item mode Define the drawing mode. @table @samp @item wires Draw white/gray wires on black background. @item colormix Mix the colors to create a paint/cartoon effect. @end table Default value is @var{wires}. @end table @subsection Examples @itemize @item Standard edge detection with custom values for the hysteresis thresholding: @example edgedetect=low=0.1:high=0.4 @end example @item Painting effect without thresholding: @example edgedetect=mode=colormix:high=0 @end example @end itemize @section extractplanes Extract color channel components from input video stream into separate grayscale video streams. The filter accepts the following option: @table @option @item planes Set plane(s) to extract. Available values for planes are: @table @samp @item y @item u @item v @item a @item r @item g @item b @end table Choosing planes not available in the input will result in an error. That means you cannot select @code{r}, @code{g}, @code{b} planes with @code{y}, @code{u}, @code{v} planes at same time. @end table @subsection Examples @itemize @item Extract luma, u and v color channel component from input video frame into 3 grayscale outputs: @example ffmpeg -i video.avi -filter_complex 'extractplanes=y+u+v[y][u][v]' -map '[y]' y.avi -map '[u]' u.avi -map '[v]' v.avi @end example @end itemize @section elbg Apply a posterize effect using the ELBG (Enhanced LBG) algorithm. For each input image, the filter will compute the optimal mapping from the input to the output given the codebook length, that is the number of distinct output colors. This filter accepts the following options. @table @option @item codebook_length, l Set codebook length. The value must be a positive integer, and represents the number of distinct output colors. Default value is 256. @item nb_steps, n Set the maximum number of iterations to apply for computing the optimal mapping. The higher the value the better the result and the higher the computation time. Default value is 1. @item seed, s Set a random seed, must be an integer included between 0 and UINT32_MAX. If not specified, or if explicitly set to -1, the filter will try to use a good random seed on a best effort basis. @end table @section fade Apply a fade-in/out effect to the input video. It accepts the following parameters: @table @option @item type, t The effect type can be either "in" for a fade-in, or "out" for a fade-out effect. Default is @code{in}. @item start_frame, s Specify the number of the frame to start applying the fade effect at. Default is 0. @item nb_frames, n The number of frames that the fade effect lasts. At the end of the fade-in effect, the output video will have the same intensity as the input video. At the end of the fade-out transition, the output video will be filled with the selected @option{color}. Default is 25. @item alpha If set to 1, fade only alpha channel, if one exists on the input. Default value is 0. @item start_time, st Specify the timestamp (in seconds) of the frame to start to apply the fade effect. If both start_frame and start_time are specified, the fade will start at whichever comes last. Default is 0. @item duration, d The number of seconds for which the fade effect has to last. At the end of the fade-in effect the output video will have the same intensity as the input video, at the end of the fade-out transition the output video will be filled with the selected @option{color}. If both duration and nb_frames are specified, duration is used. Default is 0. @item color, c Specify the color of the fade. Default is "black". @end table @subsection Examples @itemize @item Fade in the first 30 frames of video: @example fade=in:0:30 @end example The command above is equivalent to: @example fade=t=in:s=0:n=30 @end example @item Fade out the last 45 frames of a 200-frame video: @example fade=out:155:45 fade=type=out:start_frame=155:nb_frames=45 @end example @item Fade in the first 25 frames and fade out the last 25 frames of a 1000-frame video: @example fade=in:0:25, fade=out:975:25 @end example @item Make the first 5 frames yellow, then fade in from frame 5-24: @example fade=in:5:20:color=yellow @end example @item Fade in alpha over first 25 frames of video: @example fade=in:0:25:alpha=1 @end example @item Make the first 5.5 seconds black, then fade in for 0.5 seconds: @example fade=t=in:st=5.5:d=0.5 @end example @end itemize @section field Extract a single field from an interlaced image using stride arithmetic to avoid wasting CPU time. The output frames are marked as non-interlaced. The filter accepts the following options: @table @option @item type Specify whether to extract the top (if the value is @code{0} or @code{top}) or the bottom field (if the value is @code{1} or @code{bottom}). @end table @section fieldmatch Field matching filter for inverse telecine. It is meant to reconstruct the progressive frames from a telecined stream. The filter does not drop duplicated frames, so to achieve a complete inverse telecine @code{fieldmatch} needs to be followed by a decimation filter such as @ref{decimate} in the filtergraph. The separation of the field matching and the decimation is notably motivated by the possibility of inserting a de-interlacing filter fallback between the two. If the source has mixed telecined and real interlaced content, @code{fieldmatch} will not be able to match fields for the interlaced parts. But these remaining combed frames will be marked as interlaced, and thus can be de-interlaced by a later filter such as @ref{yadif} before decimation. In addition to the various configuration options, @code{fieldmatch} can take an optional second stream, activated through the @option{ppsrc} option. If enabled, the frames reconstruction will be based on the fields and frames from this second stream. This allows the first input to be pre-processed in order to help the various algorithms of the filter, while keeping the output lossless (assuming the fields are matched properly). Typically, a field-aware denoiser, or brightness/contrast adjustments can help. Note that this filter uses the same algorithms as TIVTC/TFM (AviSynth project) and VIVTC/VFM (VapourSynth project). The later is a light clone of TFM from which @code{fieldmatch} is based on. While the semantic and usage are very close, some behaviour and options names can differ. The @ref{decimate} filter currently only works for constant frame rate input. Do not use @code{fieldmatch} and @ref{decimate} if your input has mixed telecined and progressive content with changing framerate. The filter accepts the following options: @table @option @item order Specify the assumed field order of the input stream. Available values are: @table @samp @item auto Auto detect parity (use FFmpeg's internal parity value). @item bff Assume bottom field first. @item tff Assume top field first. @end table Note that it is sometimes recommended not to trust the parity announced by the stream. Default value is @var{auto}. @item mode Set the matching mode or strategy to use. @option{pc} mode is the safest in the sense that it won't risk creating jerkiness due to duplicate frames when possible, but if there are bad edits or blended fields it will end up outputting combed frames when a good match might actually exist. On the other hand, @option{pcn_ub} mode is the most risky in terms of creating jerkiness, but will almost always find a good frame if there is one. The other values are all somewhere in between @option{pc} and @option{pcn_ub} in terms of risking jerkiness and creating duplicate frames versus finding good matches in sections with bad edits, orphaned fields, blended fields, etc. More details about p/c/n/u/b are available in @ref{p/c/n/u/b meaning} section. Available values are: @table @samp @item pc 2-way matching (p/c) @item pc_n 2-way matching, and trying 3rd match if still combed (p/c + n) @item pc_u 2-way matching, and trying 3rd match (same order) if still combed (p/c + u) @item pc_n_ub 2-way matching, trying 3rd match if still combed, and trying 4th/5th matches if still combed (p/c + n + u/b) @item pcn 3-way matching (p/c/n) @item pcn_ub 3-way matching, and trying 4th/5th matches if all 3 of the original matches are detected as combed (p/c/n + u/b) @end table The parenthesis at the end indicate the matches that would be used for that mode assuming @option{order}=@var{tff} (and @option{field} on @var{auto} or @var{top}). In terms of speed @option{pc} mode is by far the fastest and @option{pcn_ub} is the slowest. Default value is @var{pc_n}. @item ppsrc Mark the main input stream as a pre-processed input, and enable the secondary input stream as the clean source to pick the fields from. See the filter introduction for more details. It is similar to the @option{clip2} feature from VFM/TFM. Default value is @code{0} (disabled). @item field Set the field to match from. It is recommended to set this to the same value as @option{order} unless you experience matching failures with that setting. In certain circumstances changing the field that is used to match from can have a large impact on matching performance. Available values are: @table @samp @item auto Automatic (same value as @option{order}). @item bottom Match from the bottom field. @item top Match from the top field. @end table Default value is @var{auto}. @item mchroma Set whether or not chroma is included during the match comparisons. In most cases it is recommended to leave this enabled. You should set this to @code{0} only if your clip has bad chroma problems such as heavy rainbowing or other artifacts. Setting this to @code{0} could also be used to speed things up at the cost of some accuracy. Default value is @code{1}. @item y0 @item y1 These define an exclusion band which excludes the lines between @option{y0} and @option{y1} from being included in the field matching decision. An exclusion band can be used to ignore subtitles, a logo, or other things that may interfere with the matching. @option{y0} sets the starting scan line and @option{y1} sets the ending line; all lines in between @option{y0} and @option{y1} (including @option{y0} and @option{y1}) will be ignored. Setting @option{y0} and @option{y1} to the same value will disable the feature. @option{y0} and @option{y1} defaults to @code{0}. @item scthresh Set the scene change detection threshold as a percentage of maximum change on the luma plane. Good values are in the @code{[8.0, 14.0]} range. Scene change detection is only relevant in case @option{combmatch}=@var{sc}. The range for @option{scthresh} is @code{[0.0, 100.0]}. Default value is @code{12.0}. @item combmatch When @option{combatch} is not @var{none}, @code{fieldmatch} will take into account the combed scores of matches when deciding what match to use as the final match. Available values are: @table @samp @item none No final matching based on combed scores. @item sc Combed scores are only used when a scene change is detected. @item full Use combed scores all the time. @end table Default is @var{sc}. @item combdbg Force @code{fieldmatch} to calculate the combed metrics for certain matches and print them. This setting is known as @option{micout} in TFM/VFM vocabulary. Available values are: @table @samp @item none No forced calculation. @item pcn Force p/c/n calculations. @item pcnub Force p/c/n/u/b calculations. @end table Default value is @var{none}. @item cthresh This is the area combing threshold used for combed frame detection. This essentially controls how "strong" or "visible" combing must be to be detected. Larger values mean combing must be more visible and smaller values mean combing can be less visible or strong and still be detected. Valid settings are from @code{-1} (every pixel will be detected as combed) to @code{255} (no pixel will be detected as combed). This is basically a pixel difference value. A good range is @code{[8, 12]}. Default value is @code{9}. @item chroma Sets whether or not chroma is considered in the combed frame decision. Only disable this if your source has chroma problems (rainbowing, etc.) that are causing problems for the combed frame detection with chroma enabled. Actually, using @option{chroma}=@var{0} is usually more reliable, except for the case where there is chroma only combing in the source. Default value is @code{0}. @item blockx @item blocky Respectively set the x-axis and y-axis size of the window used during combed frame detection. This has to do with the size of the area in which @option{combpel} pixels are required to be detected as combed for a frame to be declared combed. See the @option{combpel} parameter description for more info. Possible values are any number that is a power of 2 starting at 4 and going up to 512. Default value is @code{16}. @item combpel The number of combed pixels inside any of the @option{blocky} by @option{blockx} size blocks on the frame for the frame to be detected as combed. While @option{cthresh} controls how "visible" the combing must be, this setting controls "how much" combing there must be in any localized area (a window defined by the @option{blockx} and @option{blocky} settings) on the frame. Minimum value is @code{0} and maximum is @code{blocky x blockx} (at which point no frames will ever be detected as combed). This setting is known as @option{MI} in TFM/VFM vocabulary. Default value is @code{80}. @end table @anchor{p/c/n/u/b meaning} @subsection p/c/n/u/b meaning @subsubsection p/c/n We assume the following telecined stream: @example Top fields: 1 2 2 3 4 Bottom fields: 1 2 3 4 4 @end example The numbers correspond to the progressive frame the fields relate to. Here, the first two frames are progressive, the 3rd and 4th are combed, and so on. When @code{fieldmatch} is configured to run a matching from bottom (@option{field}=@var{bottom}) this is how this input stream get transformed: @example Input stream: T 1 2 2 3 4 B 1 2 3 4 4 <-- matching reference Matches: c c n n c Output stream: T 1 2 3 4 4 B 1 2 3 4 4 @end example As a result of the field matching, we can see that some frames get duplicated. To perform a complete inverse telecine, you need to rely on a decimation filter after this operation. See for instance the @ref{decimate} filter. The same operation now matching from top fields (@option{field}=@var{top}) looks like this: @example Input stream: T 1 2 2 3 4 <-- matching reference B 1 2 3 4 4 Matches: c c p p c Output stream: T 1 2 2 3 4 B 1 2 2 3 4 @end example In these examples, we can see what @var{p}, @var{c} and @var{n} mean; basically, they refer to the frame and field of the opposite parity: @itemize @item @var{p} matches the field of the opposite parity in the previous frame @item @var{c} matches the field of the opposite parity in the current frame @item @var{n} matches the field of the opposite parity in the next frame @end itemize @subsubsection u/b The @var{u} and @var{b} matching are a bit special in the sense that they match from the opposite parity flag. In the following examples, we assume that we are currently matching the 2nd frame (Top:2, bottom:2). According to the match, a 'x' is placed above and below each matched fields. With bottom matching (@option{field}=@var{bottom}): @example Match: c p n b u x x x x x Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 x x x x x Output frames: 2 1 2 2 2 2 2 2 1 3 @end example With top matching (@option{field}=@var{top}): @example Match: c p n b u x x x x x Top 1 2 2 1 2 2 1 2 2 1 2 2 1 2 2 Bottom 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 x x x x x Output frames: 2 2 2 1 2 2 1 3 2 2 @end example @subsection Examples Simple IVTC of a top field first telecined stream: @example fieldmatch=order=tff:combmatch=none, decimate @end example Advanced IVTC, with fallback on @ref{yadif} for still combed frames: @example fieldmatch=order=tff:combmatch=full, yadif=deint=interlaced, decimate @end example @section fieldorder Transform the field order of the input video. It accepts the following parameters: @table @option @item order The output field order. Valid values are @var{tff} for top field first or @var{bff} for bottom field first. @end table The default value is @samp{tff}. The transformation is done by shifting the picture content up or down by one line, and filling the remaining line with appropriate picture content. This method is consistent with most broadcast field order converters. If the input video is not flagged as being interlaced, or it is already flagged as being of the required output field order, then this filter does not alter the incoming video. It is very useful when converting to or from PAL DV material, which is bottom field first. For example: @example ffmpeg -i in.vob -vf "fieldorder=bff" out.dv @end example @section fifo Buffer input images and send them when they are requested. It is mainly useful when auto-inserted by the libavfilter framework. It does not take parameters. @anchor{format} @section format Convert the input video to one of the specified pixel formats. Libavfilter will try to pick one that is suitable as input to the next filter. It accepts the following parameters: @table @option @item pix_fmts A '|'-separated list of pixel format names, such as "pix_fmts=yuv420p|monow|rgb24". @end table @subsection Examples @itemize @item Convert the input video to the @var{yuv420p} format @example format=pix_fmts=yuv420p @end example Convert the input video to any of the formats in the list @example format=pix_fmts=yuv420p|yuv444p|yuv410p @end example @end itemize @anchor{fps} @section fps Convert the video to specified constant frame rate by duplicating or dropping frames as necessary. It accepts the following parameters: @table @option @item fps The desired output frame rate. The default is @code{25}. @item round Rounding method. Possible values are: @table @option @item zero zero round towards 0 @item inf round away from 0 @item down round towards -infinity @item up round towards +infinity @item near round to nearest @end table The default is @code{near}. @item start_time Assume the first PTS should be the given value, in seconds. This allows for padding/trimming at the start of stream. By default, no assumption is made about the first frame's expected PTS, so no padding or trimming is done. For example, this could be set to 0 to pad the beginning with duplicates of the first frame if a video stream starts after the audio stream or to trim any frames with a negative PTS. @end table Alternatively, the options can be specified as a flat string: @var{fps}[:@var{round}]. See also the @ref{setpts} filter. @subsection Examples @itemize @item A typical usage in order to set the fps to 25: @example fps=fps=25 @end example @item Sets the fps to 24, using abbreviation and rounding method to round to nearest: @example fps=fps=film:round=near @end example @end itemize @section framepack Pack two different video streams into a stereoscopic video, setting proper metadata on supported codecs. The two views should have the same size and framerate and processing will stop when the shorter video ends. Please note that you may conveniently adjust view properties with the @ref{scale} and @ref{fps} filters. It accepts the following parameters: @table @option @item format The desired packing format. Supported values are: @table @option @item sbs The views are next to each other (default). @item tab The views are on top of each other. @item lines The views are packed by line. @item columns The views are packed by column. @item frameseq The views are temporally interleaved. @end table @end table Some examples: @example # Convert left and right views into a frame-sequential video ffmpeg -i LEFT -i RIGHT -filter_complex framepack=frameseq OUTPUT # Convert views into a side-by-side video with the same output resolution as the input ffmpeg -i LEFT -i RIGHT -filter_complex [0:v]scale=w=iw/2[left],[1:v]scale=w=iw/2[right],[left][right]framepack=sbs OUTPUT @end example @section framestep Select one frame every N-th frame. This filter accepts the following option: @table @option @item step Select frame after every @code{step} frames. Allowed values are positive integers higher than 0. Default value is @code{1}. @end table @anchor{frei0r} @section frei0r Apply a frei0r effect to the input video. To enable the compilation of this filter, you need to install the frei0r header and configure FFmpeg with @code{--enable-frei0r}. It accepts the following parameters: @table @option @item filter_name The name of the frei0r effect to load. If the environment variable @env{FREI0R_PATH} is defined, the frei0r effect is searched for in each of the directories specified by the colon-separated list in @env{FREIOR_PATH}. Otherwise, the standard frei0r paths are searched, in this order: @file{HOME/.frei0r-1/lib/}, @file{/usr/local/lib/frei0r-1/}, @file{/usr/lib/frei0r-1/}. @item filter_params A '|'-separated list of parameters to pass to the frei0r effect. @end table A frei0r effect parameter can be a boolean (its value is either "y" or "n"), a double, a color (specified as @var{R}/@var{G}/@var{B}, where @var{R}, @var{G}, and @var{B} are floating point numbers between 0.0 and 1.0, inclusive) or by a color description specified in the "Color" section in the ffmpeg-utils manual), a position (specified as @var{X}/@var{Y}, where @var{X} and @var{Y} are floating point numbers) and/or a string. The number and types of parameters depend on the loaded effect. If an effect parameter is not specified, the default value is set. @subsection Examples @itemize @item Apply the distort0r effect, setting the first two double parameters: @example frei0r=filter_name=distort0r:filter_params=0.5|0.01 @end example @item Apply the colordistance effect, taking a color as the first parameter: @example frei0r=colordistance:0.2/0.3/0.4 frei0r=colordistance:violet frei0r=colordistance:0x112233 @end example @item Apply the perspective effect, specifying the top left and top right image positions: @example frei0r=perspective:0.2/0.2|0.8/0.2 @end example @end itemize For more information, see @url{http://frei0r.dyne.org} @section geq The filter accepts the following options: @table @option @item lum_expr, lum Set the luminance expression. @item cb_expr, cb Set the chrominance blue expression. @item cr_expr, cr Set the chrominance red expression. @item alpha_expr, a Set the alpha expression. @item red_expr, r Set the red expression. @item green_expr, g Set the green expression. @item blue_expr, b Set the blue expression. @end table The colorspace is selected according to the specified options. If one of the @option{lum_expr}, @option{cb_expr}, or @option{cr_expr} options is specified, the filter will automatically select a YCbCr colorspace. If one of the @option{red_expr}, @option{green_expr}, or @option{blue_expr} options is specified, it will select an RGB colorspace. If one of the chrominance expression is not defined, it falls back on the other one. If no alpha expression is specified it will evaluate to opaque value. If none of chrominance expressions are specified, they will evaluate to the luminance expression. The expressions can use the following variables and functions: @table @option @item N The sequential number of the filtered frame, starting from @code{0}. @item X @item Y The coordinates of the current sample. @item W @item H The width and height of the image. @item SW @item SH Width and height scale depending on the currently filtered plane. It is the ratio between the corresponding luma plane number of pixels and the current plane ones. E.g. for YUV4:2:0 the values are @code{1,1} for the luma plane, and @code{0.5,0.5} for chroma planes. @item T Time of the current frame, expressed in seconds. @item p(x, y) Return the value of the pixel at location (@var{x},@var{y}) of the current plane. @item lum(x, y) Return the value of the pixel at location (@var{x},@var{y}) of the luminance plane. @item cb(x, y) Return the value of the pixel at location (@var{x},@var{y}) of the blue-difference chroma plane. Return 0 if there is no such plane. @item cr(x, y) Return the value of the pixel at location (@var{x},@var{y}) of the red-difference chroma plane. Return 0 if there is no such plane. @item r(x, y) @item g(x, y) @item b(x, y) Return the value of the pixel at location (@var{x},@var{y}) of the red/green/blue component. Return 0 if there is no such component. @item alpha(x, y) Return the value of the pixel at location (@var{x},@var{y}) of the alpha plane. Return 0 if there is no such plane. @end table For functions, if @var{x} and @var{y} are outside the area, the value will be automatically clipped to the closer edge. @subsection Examples @itemize @item Flip the image horizontally: @example geq=p(W-X\,Y) @end example @item Generate a bidimensional sine wave, with angle @code{PI/3} and a wavelength of 100 pixels: @example geq=128 + 100*sin(2*(PI/100)*(cos(PI/3)*(X-50*T) + sin(PI/3)*Y)):128:128 @end example @item Generate a fancy enigmatic moving light: @example nullsrc=s=256x256,geq=random(1)/hypot(X-cos(N*0.07)*W/2-W/2\,Y-sin(N*0.09)*H/2-H/2)^2*1000000*sin(N*0.02):128:128 @end example @item Generate a quick emboss effect: @example format=gray,geq=lum_expr='(p(X,Y)+(256-p(X-4,Y-4)))/2' @end example @item Modify RGB components depending on pixel position: @example geq=r='X/W*r(X,Y)':g='(1-X/W)*g(X,Y)':b='(H-Y)/H*b(X,Y)' @end example @item Create a radial gradient that is the same size as the input (also see the @ref{vignette} filter): @example geq=lum=255*gauss((X/W-0.5)*3)*gauss((Y/H-0.5)*3)/gauss(0)/gauss(0),format=gray @end example @item Create a linear gradient to use as a mask for another filter, then compose with @ref{overlay}. In this example the video will gradually become more blurry from the top to the bottom of the y-axis as defined by the linear gradient: @example ffmpeg -i input.mp4 -filter_complex "geq=lum=255*(Y/H),format=gray[grad];[0:v]boxblur=4[blur];[blur][grad]alphamerge[alpha];[0:v][alpha]overlay" output.mp4 @end example @end itemize @section gradfun Fix the banding artifacts that are sometimes introduced into nearly flat regions by truncation to 8bit color depth. Interpolate the gradients that should go where the bands are, and dither them. It is designed for playback only. Do not use it prior to lossy compression, because compression tends to lose the dither and bring back the bands. It accepts the following parameters: @table @option @item strength The maximum amount by which the filter will change any one pixel. This is also the threshold for detecting nearly flat regions. Acceptable values range from .51 to 64; the default value is 1.2. Out-of-range values will be clipped to the valid range. @item radius The neighborhood to fit the gradient to. A larger radius makes for smoother gradients, but also prevents the filter from modifying the pixels near detailed regions. Acceptable values are 8-32; the default value is 16. Out-of-range values will be clipped to the valid range. @end table Alternatively, the options can be specified as a flat string: @var{strength}[:@var{radius}] @subsection Examples @itemize @item Apply the filter with a @code{3.5} strength and radius of @code{8}: @example gradfun=3.5:8 @end example @item Specify radius, omitting the strength (which will fall-back to the default value): @example gradfun=radius=8 @end example @end itemize @anchor{haldclut} @section haldclut Apply a Hald CLUT to a video stream. First input is the video stream to process, and second one is the Hald CLUT. The Hald CLUT input can be a simple picture or a complete video stream. The filter accepts the following options: @table @option @item shortest Force termination when the shortest input terminates. Default is @code{0}. @item repeatlast Continue applying the last CLUT after the end of the stream. A value of @code{0} disable the filter after the last frame of the CLUT is reached. Default is @code{1}. @end table @code{haldclut} also has the same interpolation options as @ref{lut3d} (both filters share the same internals). More information about the Hald CLUT can be found on Eskil Steenberg's website (Hald CLUT author) at @url{http://www.quelsolaar.com/technology/clut.html}. @subsection Workflow examples @subsubsection Hald CLUT video stream Generate an identity Hald CLUT stream altered with various effects: @example ffmpeg -f lavfi -i @ref{haldclutsrc}=8 -vf "hue=H=2*PI*t:s=sin(2*PI*t)+1, curves=cross_process" -t 10 -c:v ffv1 clut.nut @end example Note: make sure you use a lossless codec. Then use it with @code{haldclut} to apply it on some random stream: @example ffmpeg -f lavfi -i mandelbrot -i clut.nut -filter_complex '[0][1] haldclut' -t 20 mandelclut.mkv @end example The Hald CLUT will be applied to the 10 first seconds (duration of @file{clut.nut}), then the latest picture of that CLUT stream will be applied to the remaining frames of the @code{mandelbrot} stream. @subsubsection Hald CLUT with preview A Hald CLUT is supposed to be a squared image of @code{Level*Level*Level} by @code{Level*Level*Level} pixels. For a given Hald CLUT, FFmpeg will select the biggest possible square starting at the top left of the picture. The remaining padding pixels (bottom or right) will be ignored. This area can be used to add a preview of the Hald CLUT. Typically, the following generated Hald CLUT will be supported by the @code{haldclut} filter: @example ffmpeg -f lavfi -i @ref{haldclutsrc}=8 -vf " pad=iw+320 [padded_clut]; smptebars=s=320x256, split [a][b]; [padded_clut][a] overlay=W-320:h, curves=color_negative [main]; [main][b] overlay=W-320" -frames:v 1 clut.png @end example It contains the original and a preview of the effect of the CLUT: SMPTE color bars are displayed on the right-top, and below the same color bars processed by the color changes. Then, the effect of this Hald CLUT can be visualized with: @example ffplay input.mkv -vf "movie=clut.png, [in] haldclut" @end example @section hflip Flip the input video horizontally. For example, to horizontally flip the input video with @command{ffmpeg}: @example ffmpeg -i in.avi -vf "hflip" out.avi @end example @section histeq This filter applies a global color histogram equalization on a per-frame basis. It can be used to correct video that has a compressed range of pixel intensities. The filter redistributes the pixel intensities to equalize their distribution across the intensity range. It may be viewed as an "automatically adjusting contrast filter". This filter is useful only for correcting degraded or poorly captured source video. The filter accepts the following options: @table @option @item strength Determine the amount of equalization to be applied. As the strength is reduced, the distribution of pixel intensities more-and-more approaches that of the input frame. The value must be a float number in the range [0,1] and defaults to 0.200. @item intensity Set the maximum intensity that can generated and scale the output values appropriately. The strength should be set as desired and then the intensity can be limited if needed to avoid washing-out. The value must be a float number in the range [0,1] and defaults to 0.210. @item antibanding Set the antibanding level. If enabled the filter will randomly vary the luminance of output pixels by a small amount to avoid banding of the histogram. Possible values are @code{none}, @code{weak} or @code{strong}. It defaults to @code{none}. @end table @section histogram Compute and draw a color distribution histogram for the input video. The computed histogram is a representation of the color component distribution in an image. The filter accepts the following options: @table @option @item mode Set histogram mode. It accepts the following values: @table @samp @item levels Standard histogram that displays the color components distribution in an image. Displays color graph for each color component. Shows distribution of the Y, U, V, A or R, G, B components, depending on input format, in the current frame. Below each graph a color component scale meter is shown. @item color Displays chroma values (U/V color placement) in a two dimensional graph (which is called a vectorscope). The brighter a pixel in the vectorscope, the more pixels of the input frame correspond to that pixel (i.e., more pixels have this chroma value). The V component is displayed on the horizontal (X) axis, with the leftmost side being V = 0 and the rightmost side being V = 255. The U component is displayed on the vertical (Y) axis, with the top representing U = 0 and the bottom representing U = 255. The position of a white pixel in the graph corresponds to the chroma value of a pixel of the input clip. The graph can therefore be used to read the hue (color flavor) and the saturation (the dominance of the hue in the color). As the hue of a color changes, it moves around the square. At the center of the square the saturation is zero, which means that the corresponding pixel has no color. If the amount of a specific color is increased (while leaving the other colors unchanged) the saturation increases, and the indicator moves towards the edge of the square. @item color2 Chroma values in vectorscope, similar as @code{color} but actual chroma values are displayed. @item waveform Per row/column color component graph. In row mode, the graph on the left side represents color component value 0 and the right side represents value = 255. In column mode, the top side represents color component value = 0 and bottom side represents value = 255. @end table Default value is @code{levels}. @item level_height Set height of level in @code{levels}. Default value is @code{200}. Allowed range is [50, 2048]. @item scale_height Set height of color scale in @code{levels}. Default value is @code{12}. Allowed range is [0, 40]. @item step Set step for @code{waveform} mode. Smaller values are useful to find out how many values of the same luminance are distributed across input rows/columns. Default value is @code{10}. Allowed range is [1, 255]. @item waveform_mode Set mode for @code{waveform}. Can be either @code{row}, or @code{column}. Default is @code{row}. @item waveform_mirror Set mirroring mode for @code{waveform}. @code{0} means unmirrored, @code{1} means mirrored. In mirrored mode, higher values will be represented on the left side for @code{row} mode and at the top for @code{column} mode. Default is @code{0} (unmirrored). @item display_mode Set display mode for @code{waveform} and @code{levels}. It accepts the following values: @table @samp @item parade Display separate graph for the color components side by side in @code{row} waveform mode or one below the other in @code{column} waveform mode for @code{waveform} histogram mode. For @code{levels} histogram mode, per color component graphs are placed below each other. Using this display mode in @code{waveform} histogram mode makes it easy to spot color casts in the highlights and shadows of an image, by comparing the contours of the top and the bottom graphs of each waveform. Since whites, grays, and blacks are characterized by exactly equal amounts of red, green, and blue, neutral areas of the picture should display three waveforms of roughly equal width/height. If not, the correction is easy to perform by making level adjustments the three waveforms. @item overlay Presents information identical to that in the @code{parade}, except that the graphs representing color components are superimposed directly over one another. This display mode in @code{waveform} histogram mode makes it easier to spot relative differences or similarities in overlapping areas of the color components that are supposed to be identical, such as neutral whites, grays, or blacks. @end table Default is @code{parade}. @item levels_mode Set mode for @code{levels}. Can be either @code{linear}, or @code{logarithmic}. Default is @code{linear}. @end table @subsection Examples @itemize @item Calculate and draw histogram: @example ffplay -i input -vf histogram @end example @end itemize @anchor{hqdn3d} @section hqdn3d This is a high precision/quality 3d denoise filter. It aims to reduce image noise, producing smooth images and making still images really still. It should enhance compressibility. It accepts the following optional parameters: @table @option @item luma_spatial A non-negative floating point number which specifies spatial luma strength. It defaults to 4.0. @item chroma_spatial A non-negative floating point number which specifies spatial chroma strength. It defaults to 3.0*@var{luma_spatial}/4.0. @item luma_tmp A floating point number which specifies luma temporal strength. It defaults to 6.0*@var{luma_spatial}/4.0. @item chroma_tmp A floating point number which specifies chroma temporal strength. It defaults to @var{luma_tmp}*@var{chroma_spatial}/@var{luma_spatial}. @end table @section hqx Apply a high-quality magnification filter designed for pixel art. This filter was originally created by Maxim Stepin. It accepts the following option: @table @option @item n Set the scaling dimension: @code{2} for @code{hq2x}, @code{3} for @code{hq3x} and @code{4} for @code{hq4x}. Default is @code{3}. @end table @section hue Modify the hue and/or the saturation of the input. It accepts the following parameters: @table @option @item h Specify the hue angle as a number of degrees. It accepts an expression, and defaults to "0". @item s Specify the saturation in the [-10,10] range. It accepts an expression and defaults to "1". @item H Specify the hue angle as a number of radians. It accepts an expression, and defaults to "0". @item b Specify the brightness in the [-10,10] range. It accepts an expression and defaults to "0". @end table @option{h} and @option{H} are mutually exclusive, and can't be specified at the same time. The @option{b}, @option{h}, @option{H} and @option{s} option values are expressions containing the following constants: @table @option @item n frame count of the input frame starting from 0 @item pts presentation timestamp of the input frame expressed in time base units @item r frame rate of the input video, NAN if the input frame rate is unknown @item t timestamp expressed in seconds, NAN if the input timestamp is unknown @item tb time base of the input video @end table @subsection Examples @itemize @item Set the hue to 90 degrees and the saturation to 1.0: @example hue=h=90:s=1 @end example @item Same command but expressing the hue in radians: @example hue=H=PI/2:s=1 @end example @item Rotate hue and make the saturation swing between 0 and 2 over a period of 1 second: @example hue="H=2*PI*t: s=sin(2*PI*t)+1" @end example @item Apply a 3 seconds saturation fade-in effect starting at 0: @example hue="s=min(t/3\,1)" @end example The general fade-in expression can be written as: @example hue="s=min(0\, max((t-START)/DURATION\, 1))" @end example @item Apply a 3 seconds saturation fade-out effect starting at 5 seconds: @example hue="s=max(0\, min(1\, (8-t)/3))" @end example The general fade-out expression can be written as: @example hue="s=max(0\, min(1\, (START+DURATION-t)/DURATION))" @end example @end itemize @subsection Commands This filter supports the following commands: @table @option @item b @item s @item h @item H Modify the hue and/or the saturation and/or brightness of the input video. The command accepts the same syntax of the corresponding option. If the specified expression is not valid, it is kept at its current value. @end table @section idet Detect video interlacing type. This filter tries to detect if the input frames as interlaced, progressive, top or bottom field first. It will also try and detect fields that are repeated between adjacent frames (a sign of telecine). Single frame detection considers only immediately adjacent frames when classifying each frame. Multiple frame detection incorporates the classification history of previous frames. The filter will log these metadata values: @table @option @item single.current_frame Detected type of current frame using single-frame detection. One of: ``tff'' (top field first), ``bff'' (bottom field first), ``progressive'', or ``undetermined'' @item single.tff Cumulative number of frames detected as top field first using single-frame detection. @item multiple.tff Cumulative number of frames detected as top field first using multiple-frame detection. @item single.bff Cumulative number of frames detected as bottom field first using single-frame detection. @item multiple.current_frame Detected type of current frame using multiple-frame detection. One of: ``tff'' (top field first), ``bff'' (bottom field first), ``progressive'', or ``undetermined'' @item multiple.bff Cumulative number of frames detected as bottom field first using multiple-frame detection. @item single.progressive Cumulative number of frames detected as progressive using single-frame detection. @item multiple.progressive Cumulative number of frames detected as progressive using multiple-frame detection. @item single.undetermined Cumulative number of frames that could not be classified using single-frame detection. @item multiple.undetermined Cumulative number of frames that could not be classified using multiple-frame detection. @item repeated.current_frame Which field in the current frame is repeated from the last. One of ``neither'', ``top'', or ``bottom''. @item repeated.neither Cumulative number of frames with no repeated field. @item repeated.top Cumulative number of frames with the top field repeated from the previous frame's top field. @item repeated.bottom Cumulative number of frames with the bottom field repeated from the previous frame's bottom field. @end table The filter accepts the following options: @table @option @item intl_thres Set interlacing threshold. @item prog_thres Set progressive threshold. @item repeat_thres Threshold for repeated field detection. @item half_life Number of frames after which a given frame's contribution to the statistics is halved (i.e., it contributes only 0.5 to it's classification). The default of 0 means that all frames seen are given full weight of 1.0 forever. @end table @section il Deinterleave or interleave fields. This filter allows one to process interlaced images fields without deinterlacing them. Deinterleaving splits the input frame into 2 fields (so called half pictures). Odd lines are moved to the top half of the output image, even lines to the bottom half. You can process (filter) them independently and then re-interleave them. The filter accepts the following options: @table @option @item luma_mode, l @item chroma_mode, c @item alpha_mode, a Available values for @var{luma_mode}, @var{chroma_mode} and @var{alpha_mode} are: @table @samp @item none Do nothing. @item deinterleave, d Deinterleave fields, placing one above the other. @item interleave, i Interleave fields. Reverse the effect of deinterleaving. @end table Default value is @code{none}. @item luma_swap, ls @item chroma_swap, cs @item alpha_swap, as Swap luma/chroma/alpha fields. Exchange even & odd lines. Default value is @code{0}. @end table @section interlace Simple interlacing filter from progressive contents. This interleaves upper (or lower) lines from odd frames with lower (or upper) lines from even frames, halving the frame rate and preserving image height. @example Original Original New Frame Frame 'j' Frame 'j+1' (tff) ========== =========== ================== Line 0 --------------------> Frame 'j' Line 0 Line 1 Line 1 ----> Frame 'j+1' Line 1 Line 2 ---------------------> Frame 'j' Line 2 Line 3 Line 3 ----> Frame 'j+1' Line 3 ... ... ... New Frame + 1 will be generated by Frame 'j+2' and Frame 'j+3' and so on @end example It accepts the following optional parameters: @table @option @item scan This determines whether the interlaced frame is taken from the even (tff - default) or odd (bff) lines of the progressive frame. @item lowpass Enable (default) or disable the vertical lowpass filter to avoid twitter interlacing and reduce moire patterns. @end table @section kerndeint Deinterlace input video by applying Donald Graft's adaptive kernel deinterling. Work on interlaced parts of a video to produce progressive frames. The description of the accepted parameters follows. @table @option @item thresh Set the threshold which affects the filter's tolerance when determining if a pixel line must be processed. It must be an integer in the range [0,255] and defaults to 10. A value of 0 will result in applying the process on every pixels. @item map Paint pixels exceeding the threshold value to white if set to 1. Default is 0. @item order Set the fields order. Swap fields if set to 1, leave fields alone if 0. Default is 0. @item sharp Enable additional sharpening if set to 1. Default is 0. @item twoway Enable twoway sharpening if set to 1. Default is 0. @end table @subsection Examples @itemize @item Apply default values: @example kerndeint=thresh=10:map=0:order=0:sharp=0:twoway=0 @end example @item Enable additional sharpening: @example kerndeint=sharp=1 @end example @item Paint processed pixels in white: @example kerndeint=map=1 @end example @end itemize @section lenscorrection Correct radial lens distortion This filter can be used to correct for radial distortion as can result from the use of wide angle lenses, and thereby re-rectify the image. To find the right parameters one can use tools available for example as part of opencv or simply trial-and-error. To use opencv use the calibration sample (under samples/cpp) from the opencv sources and extract the k1 and k2 coefficients from the resulting matrix. Note that effectively the same filter is available in the open-source tools Krita and Digikam from the KDE project. In contrast to the @ref{vignette} filter, which can also be used to compensate lens errors, this filter corrects the distortion of the image, whereas @ref{vignette} corrects the brightness distribution, so you may want to use both filters together in certain cases, though you will have to take care of ordering, i.e. whether vignetting should be applied before or after lens correction. @subsection Options The filter accepts the following options: @table @option @item cx Relative x-coordinate of the focal point of the image, and thereby the center of the distrortion. This value has a range [0,1] and is expressed as fractions of the image width. @item cy Relative y-coordinate of the focal point of the image, and thereby the center of the distrortion. This value has a range [0,1] and is expressed as fractions of the image height. @item k1 Coefficient of the quadratic correction term. 0.5 means no correction. @item k2 Coefficient of the double quadratic correction term. 0.5 means no correction. @end table The formula that generates the correction is: @var{r_src} = @var{r_tgt} * (1 + @var{k1} * (@var{r_tgt} / @var{r_0})^2 + @var{k2} * (@var{r_tgt} / @var{r_0})^4) where @var{r_0} is halve of the image diagonal and @var{r_src} and @var{r_tgt} are the distances from the focal point in the source and target images, respectively. @anchor{lut3d} @section lut3d Apply a 3D LUT to an input video. The filter accepts the following options: @table @option @item file Set the 3D LUT file name. Currently supported formats: @table @samp @item 3dl AfterEffects @item cube Iridas @item dat DaVinci @item m3d Pandora @end table @item interp Select interpolation mode. Available values are: @table @samp @item nearest Use values from the nearest defined point. @item trilinear Interpolate values using the 8 points defining a cube. @item tetrahedral Interpolate values using a tetrahedron. @end table @end table @section lut, lutrgb, lutyuv Compute a look-up table for binding each pixel component input value to an output value, and apply it to the input video. @var{lutyuv} applies a lookup table to a YUV input video, @var{lutrgb} to an RGB input video. These filters accept the following parameters: @table @option @item c0 set first pixel component expression @item c1 set second pixel component expression @item c2 set third pixel component expression @item c3 set fourth pixel component expression, corresponds to the alpha component @item r set red component expression @item g set green component expression @item b set blue component expression @item a alpha component expression @item y set Y/luminance component expression @item u set U/Cb component expression @item v set V/Cr component expression @end table Each of them specifies the expression to use for computing the lookup table for the corresponding pixel component values. The exact component associated to each of the @var{c*} options depends on the format in input. The @var{lut} filter requires either YUV or RGB pixel formats in input, @var{lutrgb} requires RGB pixel formats in input, and @var{lutyuv} requires YUV. The expressions can contain the following constants and functions: @table @option @item w @item h The input width and height. @item val The input value for the pixel component. @item clipval The input value, clipped to the @var{minval}-@var{maxval} range. @item maxval The maximum value for the pixel component. @item minval The minimum value for the pixel component. @item negval The negated value for the pixel component value, clipped to the @var{minval}-@var{maxval} range; it corresponds to the expression "maxval-clipval+minval". @item clip(val) The computed value in @var{val}, clipped to the @var{minval}-@var{maxval} range. @item gammaval(gamma) The computed gamma correction value of the pixel component value, clipped to the @var{minval}-@var{maxval} range. It corresponds to the expression "pow((clipval-minval)/(maxval-minval)\,@var{gamma})*(maxval-minval)+minval" @end table All expressions default to "val". @subsection Examples @itemize @item Negate input video: @example lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val" lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val" @end example The above is the same as: @example lutrgb="r=negval:g=negval:b=negval" lutyuv="y=negval:u=negval:v=negval" @end example @item Negate luminance: @example lutyuv=y=negval @end example @item Remove chroma components, turning the video into a graytone image: @example lutyuv="u=128:v=128" @end example @item Apply a luma burning effect: @example lutyuv="y=2*val" @end example @item Remove green and blue components: @example lutrgb="g=0:b=0" @end example @item Set a constant alpha channel value on input: @example format=rgba,lutrgb=a="maxval-minval/2" @end example @item Correct luminance gamma by a factor of 0.5: @example lutyuv=y=gammaval(0.5) @end example @item Discard least significant bits of luma: @example lutyuv=y='bitand(val, 128+64+32)' @end example @end itemize @section mergeplanes Merge color channel components from several video streams. The filter accepts up to 4 input streams, and merge selected input planes to the output video. This filter accepts the following options: @table @option @item mapping Set input to output plane mapping. Default is @code{0}. The mappings is specified as a bitmap. It should be specified as a hexadecimal number in the form 0xAa[Bb[Cc[Dd]]]. 'Aa' describes the mapping for the first plane of the output stream. 'A' sets the number of the input stream to use (from 0 to 3), and 'a' the plane number of the corresponding input to use (from 0 to 3). The rest of the mappings is similar, 'Bb' describes the mapping for the output stream second plane, 'Cc' describes the mapping for the output stream third plane and 'Dd' describes the mapping for the output stream fourth plane. @item format Set output pixel format. Default is @code{yuva444p}. @end table @subsection Examples @itemize @item Merge three gray video streams of same width and height into single video stream: @example [a0][a1][a2]mergeplanes=0x001020:yuv444p @end example @item Merge 1st yuv444p stream and 2nd gray video stream into yuva444p video stream: @example [a0][a1]mergeplanes=0x00010210:yuva444p @end example @item Swap Y and A plane in yuva444p stream: @example format=yuva444p,mergeplanes=0x03010200:yuva444p @end example @item Swap U and V plane in yuv420p stream: @example format=yuv420p,mergeplanes=0x000201:yuv420p @end example @item Cast a rgb24 clip to yuv444p: @example format=rgb24,mergeplanes=0x000102:yuv444p @end example @end itemize @section mcdeint Apply motion-compensation deinterlacing. It needs one field per frame as input and must thus be used together with yadif=1/3 or equivalent. This filter accepts the following options: @table @option @item mode Set the deinterlacing mode. It accepts one of the following values: @table @samp @item fast @item medium @item slow use iterative motion estimation @item extra_slow like @samp{slow}, but use multiple reference frames. @end table Default value is @samp{fast}. @item parity Set the picture field parity assumed for the input video. It must be one of the following values: @table @samp @item 0, tff assume top field first @item 1, bff assume bottom field first @end table Default value is @samp{bff}. @item qp Set per-block quantization parameter (QP) used by the internal encoder. Higher values should result in a smoother motion vector field but less optimal individual vectors. Default value is 1. @end table @section mp Apply an MPlayer filter to the input video. This filter provides a wrapper around some of the filters of MPlayer/MEncoder. This wrapper is considered experimental. Some of the wrapped filters may not work properly and we may drop support for them, as they will be implemented natively into FFmpeg. Thus you should avoid depending on them when writing portable scripts. The filter accepts the parameters: @var{filter_name}[:=]@var{filter_params} @var{filter_name} is the name of a supported MPlayer filter, @var{filter_params} is a string containing the parameters accepted by the named filter. The list of the currently supported filters follows: @table @var @item eq2 @item eq @item fspp @item ilpack @item pp7 @item softpulldown @item uspp @end table The parameter syntax and behavior for the listed filters are the same of the corresponding MPlayer filters. For detailed instructions check the "VIDEO FILTERS" section in the MPlayer manual. @subsection Examples @itemize @item Adjust gamma, brightness, contrast: @example mp=eq2=1.0:2:0.5 @end example @end itemize See also mplayer(1), @url{http://www.mplayerhq.hu/}. @section mpdecimate Drop frames that do not differ greatly from the previous frame in order to reduce frame rate. The main use of this filter is for very-low-bitrate encoding (e.g. streaming over dialup modem), but it could in theory be used for fixing movies that were inverse-telecined incorrectly. A description of the accepted options follows. @table @option @item max Set the maximum number of consecutive frames which can be dropped (if positive), or the minimum interval between dropped frames (if negative). If the value is 0, the frame is dropped unregarding the number of previous sequentially dropped frames. Default value is 0. @item hi @item lo @item frac Set the dropping threshold values. Values for @option{hi} and @option{lo} are for 8x8 pixel blocks and represent actual pixel value differences, so a threshold of 64 corresponds to 1 unit of difference for each pixel, or the same spread out differently over the block. A frame is a candidate for dropping if no 8x8 blocks differ by more than a threshold of @option{hi}, and if no more than @option{frac} blocks (1 meaning the whole image) differ by more than a threshold of @option{lo}. Default value for @option{hi} is 64*12, default value for @option{lo} is 64*5, and default value for @option{frac} is 0.33. @end table @section negate Negate input video. It accepts an integer in input; if non-zero it negates the alpha component (if available). The default value in input is 0. @section noformat Force libavfilter not to use any of the specified pixel formats for the input to the next filter. It accepts the following parameters: @table @option @item pix_fmts A '|'-separated list of pixel format names, such as apix_fmts=yuv420p|monow|rgb24". @end table @subsection Examples @itemize @item Force libavfilter to use a format different from @var{yuv420p} for the input to the vflip filter: @example noformat=pix_fmts=yuv420p,vflip @end example @item Convert the input video to any of the formats not contained in the list: @example noformat=yuv420p|yuv444p|yuv410p @end example @end itemize @section noise Add noise on video input frame. The filter accepts the following options: @table @option @item all_seed @item c0_seed @item c1_seed @item c2_seed @item c3_seed Set noise seed for specific pixel component or all pixel components in case of @var{all_seed}. Default value is @code{123457}. @item all_strength, alls @item c0_strength, c0s @item c1_strength, c1s @item c2_strength, c2s @item c3_strength, c3s Set noise strength for specific pixel component or all pixel components in case @var{all_strength}. Default value is @code{0}. Allowed range is [0, 100]. @item all_flags, allf @item c0_flags, c0f @item c1_flags, c1f @item c2_flags, c2f @item c3_flags, c3f Set pixel component flags or set flags for all components if @var{all_flags}. Available values for component flags are: @table @samp @item a averaged temporal noise (smoother) @item p mix random noise with a (semi)regular pattern @item t temporal noise (noise pattern changes between frames) @item u uniform noise (gaussian otherwise) @end table @end table @subsection Examples Add temporal and uniform noise to input video: @example noise=alls=20:allf=t+u @end example @section null Pass the video source unchanged to the output. @section ocv Apply a video transform using libopencv. To enable this filter, install the libopencv library and headers and configure FFmpeg with @code{--enable-libopencv}. It accepts the following parameters: @table @option @item filter_name The name of the libopencv filter to apply. @item filter_params The parameters to pass to the libopencv filter. If not specified, the default values are assumed. @end table Refer to the official libopencv documentation for more precise information: @url{http://docs.opencv.org/master/modules/imgproc/doc/filtering.html} Several libopencv filters are supported; see the following subsections. @anchor{dilate} @subsection dilate Dilate an image by using a specific structuring element. It corresponds to the libopencv function @code{cvDilate}. It accepts the parameters: @var{struct_el}|@var{nb_iterations}. @var{struct_el} represents a structuring element, and has the syntax: @var{cols}x@var{rows}+@var{anchor_x}x@var{anchor_y}/@var{shape} @var{cols} and @var{rows} represent the number of columns and rows of the structuring element, @var{anchor_x} and @var{anchor_y} the anchor point, and @var{shape} the shape for the structuring element. @var{shape} must be "rect", "cross", "ellipse", or "custom". If the value for @var{shape} is "custom", it must be followed by a string of the form "=@var{filename}". The file with name @var{filename} is assumed to represent a binary image, with each printable character corresponding to a bright pixel. When a custom @var{shape} is used, @var{cols} and @var{rows} are ignored, the number or columns and rows of the read file are assumed instead. The default value for @var{struct_el} is "3x3+0x0/rect". @var{nb_iterations} specifies the number of times the transform is applied to the image, and defaults to 1. Some examples: @example # Use the default values ocv=dilate # Dilate using a structuring element with a 5x5 cross, iterating two times ocv=filter_name=dilate:filter_params=5x5+2x2/cross|2 # Read the shape from the file diamond.shape, iterating two times. # The file diamond.shape may contain a pattern of characters like this # * # *** # ***** # *** # * # The specified columns and rows are ignored # but the anchor point coordinates are not ocv=dilate:0x0+2x2/custom=diamond.shape|2 @end example @subsection erode Erode an image by using a specific structuring element. It corresponds to the libopencv function @code{cvErode}. It accepts the parameters: @var{struct_el}:@var{nb_iterations}, with the same syntax and semantics as the @ref{dilate} filter. @subsection smooth Smooth the input video. The filter takes the following parameters: @var{type}|@var{param1}|@var{param2}|@var{param3}|@var{param4}. @var{type} is the type of smooth filter to apply, and must be one of the following values: "blur", "blur_no_scale", "median", "gaussian", or "bilateral". The default value is "gaussian". The meaning of @var{param1}, @var{param2}, @var{param3}, and @var{param4} depend on the smooth type. @var{param1} and @var{param2} accept integer positive values or 0. @var{param3} and @var{param4} accept floating point values. The default value for @var{param1} is 3. The default value for the other parameters is 0. These parameters correspond to the parameters assigned to the libopencv function @code{cvSmooth}. @anchor{overlay} @section overlay Overlay one video on top of another. It takes two inputs and has one output. The first input is the "main" video on which the second input is overlayed. It accepts the following parameters: A description of the accepted options follows. @table @option @item x @item y Set the expression for the x and y coordinates of the overlayed video on the main video. Default value is "0" for both expressions. In case the expression is invalid, it is set to a huge value (meaning that the overlay will not be displayed within the output visible area). @item eof_action The action to take when EOF is encountered on the secondary input; it accepts one of the following values: @table @option @item repeat Repeat the last frame (the default). @item endall End both streams. @item pass Pass the main input through. @end table @item eval Set when the expressions for @option{x}, and @option{y} are evaluated. It accepts the following values: @table @samp @item init only evaluate expressions once during the filter initialization or when a command is processed @item frame evaluate expressions for each incoming frame @end table Default value is @samp{frame}. @item shortest If set to 1, force the output to terminate when the shortest input terminates. Default value is 0. @item format Set the format for the output video. It accepts the following values: @table @samp @item yuv420 force YUV420 output @item yuv422 force YUV422 output @item yuv444 force YUV444 output @item rgb force RGB output @end table Default value is @samp{yuv420}. @item rgb @emph{(deprecated)} If set to 1, force the filter to accept inputs in the RGB color space. Default value is 0. This option is deprecated, use @option{format} instead. @item repeatlast If set to 1, force the filter to draw the last overlay frame over the main input until the end of the stream. A value of 0 disables this behavior. Default value is 1. @end table The @option{x}, and @option{y} expressions can contain the following parameters. @table @option @item main_w, W @item main_h, H The main input width and height. @item overlay_w, w @item overlay_h, h The overlay input width and height. @item x @item y The computed values for @var{x} and @var{y}. They are evaluated for each new frame. @item hsub @item vsub horizontal and vertical chroma subsample values of the output format. For example for the pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. @item n the number of input frame, starting from 0 @item pos the position in the file of the input frame, NAN if unknown @item t The timestamp, expressed in seconds. It's NAN if the input timestamp is unknown. @end table Note that the @var{n}, @var{pos}, @var{t} variables are available only when evaluation is done @emph{per frame}, and will evaluate to NAN when @option{eval} is set to @samp{init}. Be aware that frames are taken from each input video in timestamp order, hence, if their initial timestamps differ, it is a good idea to pass the two inputs through a @var{setpts=PTS-STARTPTS} filter to have them begin in the same zero timestamp, as the example for the @var{movie} filter does. You can chain together more overlays but you should test the efficiency of such approach. @subsection Commands This filter supports the following commands: @table @option @item x @item y Modify the x and y of the overlay input. The command accepts the same syntax of the corresponding option. If the specified expression is not valid, it is kept at its current value. @end table @subsection Examples @itemize @item Draw the overlay at 10 pixels from the bottom right corner of the main video: @example overlay=main_w-overlay_w-10:main_h-overlay_h-10 @end example Using named options the example above becomes: @example overlay=x=main_w-overlay_w-10:y=main_h-overlay_h-10 @end example @item Insert a transparent PNG logo in the bottom left corner of the input, using the @command{ffmpeg} tool with the @code{-filter_complex} option: @example ffmpeg -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output @end example @item Insert 2 different transparent PNG logos (second logo on bottom right corner) using the @command{ffmpeg} tool: @example ffmpeg -i input -i logo1 -i logo2 -filter_complex 'overlay=x=10:y=H-h-10,overlay=x=W-w-10:y=H-h-10' output @end example @item Add a transparent color layer on top of the main video; @code{WxH} must specify the size of the main input to the overlay filter: @example color=color=red@@.3:size=WxH [over]; [in][over] overlay [out] @end example @item Play an original video and a filtered version (here with the deshake filter) side by side using the @command{ffplay} tool: @example ffplay input.avi -vf 'split[a][b]; [a]pad=iw*2:ih[src]; [b]deshake[filt]; [src][filt]overlay=w' @end example The above command is the same as: @example ffplay input.avi -vf 'split[b], pad=iw*2[src], [b]deshake, [src]overlay=w' @end example @item Make a sliding overlay appearing from the left to the right top part of the screen starting since time 2: @example overlay=x='if(gte(t,2), -w+(t-2)*20, NAN)':y=0 @end example @item Compose output by putting two input videos side to side: @example ffmpeg -i left.avi -i right.avi -filter_complex " nullsrc=size=200x100 [background]; [0:v] setpts=PTS-STARTPTS, scale=100x100 [left]; [1:v] setpts=PTS-STARTPTS, scale=100x100 [right]; [background][left] overlay=shortest=1 [background+left]; [background+left][right] overlay=shortest=1:x=100 [left+right] " @end example @item Mask 10-20 seconds of a video by applying the delogo filter to a section @example ffmpeg -i test.avi -codec:v:0 wmv2 -ar 11025 -b:v 9000k -vf '[in]split[split_main][split_delogo];[split_delogo]trim=start=360:end=371,delogo=0:0:640:480[delogoed];[split_main][delogoed]overlay=eof_action=pass[out]' masked.avi @end example @item Chain several overlays in cascade: @example nullsrc=s=200x200 [bg]; testsrc=s=100x100, split=4 [in0][in1][in2][in3]; [in0] lutrgb=r=0, [bg] overlay=0:0 [mid0]; [in1] lutrgb=g=0, [mid0] overlay=100:0 [mid1]; [in2] lutrgb=b=0, [mid1] overlay=0:100 [mid2]; [in3] null, [mid2] overlay=100:100 [out0] @end example @end itemize @section owdenoise Apply Overcomplete Wavelet denoiser. The filter accepts the following options: @table @option @item depth Set depth. Larger depth values will denoise lower frequency components more, but slow down filtering. Must be an int in the range 8-16, default is @code{8}. @item luma_strength, ls Set luma strength. Must be a double value in the range 0-1000, default is @code{1.0}. @item chroma_strength, cs Set chroma strength. Must be a double value in the range 0-1000, default is @code{1.0}. @end table @section pad Add paddings to the input image, and place the original input at the provided @var{x}, @var{y} coordinates. It accepts the following parameters: @table @option @item width, w @item height, h Specify an expression for the size of the output image with the paddings added. If the value for @var{width} or @var{height} is 0, the corresponding input size is used for the output. The @var{width} expression can reference the value set by the @var{height} expression, and vice versa. The default value of @var{width} and @var{height} is 0. @item x @item y Specify the offsets to place the input image at within the padded area, with respect to the top/left border of the output image. The @var{x} expression can reference the value set by the @var{y} expression, and vice versa. The default value of @var{x} and @var{y} is 0. @item color Specify the color of the padded area. For the syntax of this option, check the "Color" section in the ffmpeg-utils manual. The default value of @var{color} is "black". @end table The value for the @var{width}, @var{height}, @var{x}, and @var{y} options are expressions containing the following constants: @table @option @item in_w @item in_h The input video width and height. @item iw @item ih These are the same as @var{in_w} and @var{in_h}. @item out_w @item out_h The output width and height (the size of the padded area), as specified by the @var{width} and @var{height} expressions. @item ow @item oh These are the same as @var{out_w} and @var{out_h}. @item x @item y The x and y offsets as specified by the @var{x} and @var{y} expressions, or NAN if not yet specified. @item a same as @var{iw} / @var{ih} @item sar input sample aspect ratio @item dar input display aspect ratio, it is the same as (@var{iw} / @var{ih}) * @var{sar} @item hsub @item vsub The horizontal and vertical chroma subsample values. For example for the pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. @end table @subsection Examples @itemize @item Add paddings with the color "violet" to the input video. The output video size is 640x480, and the top-left corner of the input video is placed at column 0, row 40 @example pad=640:480:0:40:violet @end example The example above is equivalent to the following command: @example pad=width=640:height=480:x=0:y=40:color=violet @end example @item Pad the input to get an output with dimensions increased by 3/2, and put the input video at the center of the padded area: @example pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2" @end example @item Pad the input to get a squared output with size equal to the maximum value between the input width and height, and put the input video at the center of the padded area: @example pad="max(iw\,ih):ow:(ow-iw)/2:(oh-ih)/2" @end example @item Pad the input to get a final w/h ratio of 16:9: @example pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2" @end example @item In case of anamorphic video, in order to set the output display aspect correctly, it is necessary to use @var{sar} in the expression, according to the relation: @example (ih * X / ih) * sar = output_dar X = output_dar / sar @end example Thus the previous example needs to be modified to: @example pad="ih*16/9/sar:ih:(ow-iw)/2:(oh-ih)/2" @end example @item Double the output size and put the input video in the bottom-right corner of the output padded area: @example pad="2*iw:2*ih:ow-iw:oh-ih" @end example @end itemize @section perspective Correct perspective of video not recorded perpendicular to the screen. A description of the accepted parameters follows. @table @option @item x0 @item y0 @item x1 @item y1 @item x2 @item y2 @item x3 @item y3 Set coordinates expression for top left, top right, bottom left and bottom right corners. Default values are @code{0:0:W:0:0:H:W:H} with which perspective will remain unchanged. If the @code{sense} option is set to @code{source}, then the specified points will be sent to the corners of the destination. If the @code{sense} option is set to @code{destination}, then the corners of the source will be sent to the specified coordinates. The expressions can use the following variables: @table @option @item W @item H the width and height of video frame. @end table @item interpolation Set interpolation for perspective correction. It accepts the following values: @table @samp @item linear @item cubic @end table Default value is @samp{linear}. @item sense Set interpretation of coordinate options. It accepts the following values: @table @samp @item 0, source Send point in the source specified by the given coordinates to the corners of the destination. @item 1, destination Send the corners of the source to the point in the destination specified by the given coordinates. Default value is @samp{source}. @end table @end table @section phase Delay interlaced video by one field time so that the field order changes. The intended use is to fix PAL movies that have been captured with the opposite field order to the film-to-video transfer. A description of the accepted parameters follows. @table @option @item mode Set phase mode. It accepts the following values: @table @samp @item t Capture field order top-first, transfer bottom-first. Filter will delay the bottom field. @item b Capture field order bottom-first, transfer top-first. Filter will delay the top field. @item p Capture and transfer with the same field order. This mode only exists for the documentation of the other options to refer to, but if you actually select it, the filter will faithfully do nothing. @item a Capture field order determined automatically by field flags, transfer opposite. Filter selects among @samp{t} and @samp{b} modes on a frame by frame basis using field flags. If no field information is available, then this works just like @samp{u}. @item u Capture unknown or varying, transfer opposite. Filter selects among @samp{t} and @samp{b} on a frame by frame basis by analyzing the images and selecting the alternative that produces best match between the fields. @item T Capture top-first, transfer unknown or varying. Filter selects among @samp{t} and @samp{p} using image analysis. @item B Capture bottom-first, transfer unknown or varying. Filter selects among @samp{b} and @samp{p} using image analysis. @item A Capture determined by field flags, transfer unknown or varying. Filter selects among @samp{t}, @samp{b} and @samp{p} using field flags and image analysis. If no field information is available, then this works just like @samp{U}. This is the default mode. @item U Both capture and transfer unknown or varying. Filter selects among @samp{t}, @samp{b} and @samp{p} using image analysis only. @end table @end table @section pixdesctest Pixel format descriptor test filter, mainly useful for internal testing. The output video should be equal to the input video. For example: @example format=monow, pixdesctest @end example can be used to test the monowhite pixel format descriptor definition. @section pp Enable the specified chain of postprocessing subfilters using libpostproc. This library should be automatically selected with a GPL build (@code{--enable-gpl}). Subfilters must be separated by '/' and can be disabled by prepending a '-'. Each subfilter and some options have a short and a long name that can be used interchangeably, i.e. dr/dering are the same. The filters accept the following options: @table @option @item subfilters Set postprocessing subfilters string. @end table All subfilters share common options to determine their scope: @table @option @item a/autoq Honor the quality commands for this subfilter. @item c/chrom Do chrominance filtering, too (default). @item y/nochrom Do luminance filtering only (no chrominance). @item n/noluma Do chrominance filtering only (no luminance). @end table These options can be appended after the subfilter name, separated by a '|'. Available subfilters are: @table @option @item hb/hdeblock[|difference[|flatness]] Horizontal deblocking filter @table @option @item difference Difference factor where higher values mean more deblocking (default: @code{32}). @item flatness Flatness threshold where lower values mean more deblocking (default: @code{39}). @end table @item vb/vdeblock[|difference[|flatness]] Vertical deblocking filter @table @option @item difference Difference factor where higher values mean more deblocking (default: @code{32}). @item flatness Flatness threshold where lower values mean more deblocking (default: @code{39}). @end table @item ha/hadeblock[|difference[|flatness]] Accurate horizontal deblocking filter @table @option @item difference Difference factor where higher values mean more deblocking (default: @code{32}). @item flatness Flatness threshold where lower values mean more deblocking (default: @code{39}). @end table @item va/vadeblock[|difference[|flatness]] Accurate vertical deblocking filter @table @option @item difference Difference factor where higher values mean more deblocking (default: @code{32}). @item flatness Flatness threshold where lower values mean more deblocking (default: @code{39}). @end table @end table The horizontal and vertical deblocking filters share the difference and flatness values so you cannot set different horizontal and vertical thresholds. @table @option @item h1/x1hdeblock Experimental horizontal deblocking filter @item v1/x1vdeblock Experimental vertical deblocking filter @item dr/dering Deringing filter @item tn/tmpnoise[|threshold1[|threshold2[|threshold3]]], temporal noise reducer @table @option @item threshold1 larger -> stronger filtering @item threshold2 larger -> stronger filtering @item threshold3 larger -> stronger filtering @end table @item al/autolevels[:f/fullyrange], automatic brightness / contrast correction @table @option @item f/fullyrange Stretch luminance to @code{0-255}. @end table @item lb/linblenddeint Linear blend deinterlacing filter that deinterlaces the given block by filtering all lines with a @code{(1 2 1)} filter. @item li/linipoldeint Linear interpolating deinterlacing filter that deinterlaces the given block by linearly interpolating every second line. @item ci/cubicipoldeint Cubic interpolating deinterlacing filter deinterlaces the given block by cubically interpolating every second line. @item md/mediandeint Median deinterlacing filter that deinterlaces the given block by applying a median filter to every second line. @item fd/ffmpegdeint FFmpeg deinterlacing filter that deinterlaces the given block by filtering every second line with a @code{(-1 4 2 4 -1)} filter. @item l5/lowpass5 Vertically applied FIR lowpass deinterlacing filter that deinterlaces the given block by filtering all lines with a @code{(-1 2 6 2 -1)} filter. @item fq/forceQuant[|quantizer] Overrides the quantizer table from the input with the constant quantizer you specify. @table @option @item quantizer Quantizer to use @end table @item de/default Default pp filter combination (@code{hb|a,vb|a,dr|a}) @item fa/fast Fast pp filter combination (@code{h1|a,v1|a,dr|a}) @item ac High quality pp filter combination (@code{ha|a|128|7,va|a,dr|a}) @end table @subsection Examples @itemize @item Apply horizontal and vertical deblocking, deringing and automatic brightness/contrast: @example pp=hb/vb/dr/al @end example @item Apply default filters without brightness/contrast correction: @example pp=de/-al @end example @item Apply default filters and temporal denoiser: @example pp=default/tmpnoise|1|2|3 @end example @item Apply deblocking on luminance only, and switch vertical deblocking on or off automatically depending on available CPU time: @example pp=hb|y/vb|a @end example @end itemize @section psnr Obtain the average, maximum and minimum PSNR (Peak Signal to Noise Ratio) between two input videos. This filter takes in input two input videos, the first input is considered the "main" source and is passed unchanged to the output. The second input is used as a "reference" video for computing the PSNR. Both video inputs must have the same resolution and pixel format for this filter to work correctly. Also it assumes that both inputs have the same number of frames, which are compared one by one. The obtained average PSNR is printed through the logging system. The filter stores the accumulated MSE (mean squared error) of each frame, and at the end of the processing it is averaged across all frames equally, and the following formula is applied to obtain the PSNR: @example PSNR = 10*log10(MAX^2/MSE) @end example Where MAX is the average of the maximum values of each component of the image. The description of the accepted parameters follows. @table @option @item stats_file, f If specified the filter will use the named file to save the PSNR of each individual frame. @end table The file printed if @var{stats_file} is selected, contains a sequence of key/value pairs of the form @var{key}:@var{value} for each compared couple of frames. A description of each shown parameter follows: @table @option @item n sequential number of the input frame, starting from 1 @item mse_avg Mean Square Error pixel-by-pixel average difference of the compared frames, averaged over all the image components. @item mse_y, mse_u, mse_v, mse_r, mse_g, mse_g, mse_a Mean Square Error pixel-by-pixel average difference of the compared frames for the component specified by the suffix. @item psnr_y, psnr_u, psnr_v, psnr_r, psnr_g, psnr_b, psnr_a Peak Signal to Noise ratio of the compared frames for the component specified by the suffix. @end table For example: @example movie=ref_movie.mpg, setpts=PTS-STARTPTS [main]; [main][ref] psnr="stats_file=stats.log" [out] @end example On this example the input file being processed is compared with the reference file @file{ref_movie.mpg}. The PSNR of each individual frame is stored in @file{stats.log}. @anchor{pullup} @section pullup Pulldown reversal (inverse telecine) filter, capable of handling mixed hard-telecine, 24000/1001 fps progressive, and 30000/1001 fps progressive content. The pullup filter is designed to take advantage of future context in making its decisions. This filter is stateless in the sense that it does not lock onto a pattern to follow, but it instead looks forward to the following fields in order to identify matches and rebuild progressive frames. To produce content with an even framerate, insert the fps filter after pullup, use @code{fps=24000/1001} if the input frame rate is 29.97fps, @code{fps=24} for 30fps and the (rare) telecined 25fps input. The filter accepts the following options: @table @option @item jl @item jr @item jt @item jb These options set the amount of "junk" to ignore at the left, right, top, and bottom of the image, respectively. Left and right are in units of 8 pixels, while top and bottom are in units of 2 lines. The default is 8 pixels on each side. @item sb Set the strict breaks. Setting this option to 1 will reduce the chances of filter generating an occasional mismatched frame, but it may also cause an excessive number of frames to be dropped during high motion sequences. Conversely, setting it to -1 will make filter match fields more easily. This may help processing of video where there is slight blurring between the fields, but may also cause there to be interlaced frames in the output. Default value is @code{0}. @item mp Set the metric plane to use. It accepts the following values: @table @samp @item l Use luma plane. @item u Use chroma blue plane. @item v Use chroma red plane. @end table This option may be set to use chroma plane instead of the default luma plane for doing filter's computations. This may improve accuracy on very clean source material, but more likely will decrease accuracy, especially if there is chroma noise (rainbow effect) or any grayscale video. The main purpose of setting @option{mp} to a chroma plane is to reduce CPU load and make pullup usable in realtime on slow machines. @end table For best results (without duplicated frames in the output file) it is necessary to change the output frame rate. For example, to inverse telecine NTSC input: @example ffmpeg -i input -vf pullup -r 24000/1001 ... @end example @section removelogo Suppress a TV station logo, using an image file to determine which pixels comprise the logo. It works by filling in the pixels that comprise the logo with neighboring pixels. The filter accepts the following options: @table @option @item filename, f Set the filter bitmap file, which can be any image format supported by libavformat. The width and height of the image file must match those of the video stream being processed. @end table Pixels in the provided bitmap image with a value of zero are not considered part of the logo, non-zero pixels are considered part of the logo. If you use white (255) for the logo and black (0) for the rest, you will be safe. For making the filter bitmap, it is recommended to take a screen capture of a black frame with the logo visible, and then using a threshold filter followed by the erode filter once or twice. If needed, little splotches can be fixed manually. Remember that if logo pixels are not covered, the filter quality will be much reduced. Marking too many pixels as part of the logo does not hurt as much, but it will increase the amount of blurring needed to cover over the image and will destroy more information than necessary, and extra pixels will slow things down on a large logo. @section rotate Rotate video by an arbitrary angle expressed in radians. The filter accepts the following options: A description of the optional parameters follows. @table @option @item angle, a Set an expression for the angle by which to rotate the input video clockwise, expressed as a number of radians. A negative value will result in a counter-clockwise rotation. By default it is set to "0". This expression is evaluated for each frame. @item out_w, ow Set the output width expression, default value is "iw". This expression is evaluated just once during configuration. @item out_h, oh Set the output height expression, default value is "ih". This expression is evaluated just once during configuration. @item bilinear Enable bilinear interpolation if set to 1, a value of 0 disables it. Default value is 1. @item fillcolor, c Set the color used to fill the output area not covered by the rotated image. For the generalsyntax of this option, check the "Color" section in the ffmpeg-utils manual. If the special value "none" is selected then no background is printed (useful for example if the background is never shown). Default value is "black". @end table The expressions for the angle and the output size can contain the following constants and functions: @table @option @item n sequential number of the input frame, starting from 0. It is always NAN before the first frame is filtered. @item t time in seconds of the input frame, it is set to 0 when the filter is configured. It is always NAN before the first frame is filtered. @item hsub @item vsub horizontal and vertical chroma subsample values. For example for the pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. @item in_w, iw @item in_h, ih the input video width and height @item out_w, ow @item out_h, oh the output width and height, that is the size of the padded area as specified by the @var{width} and @var{height} expressions @item rotw(a) @item roth(a) the minimal width/height required for completely containing the input video rotated by @var{a} radians. These are only available when computing the @option{out_w} and @option{out_h} expressions. @end table @subsection Examples @itemize @item Rotate the input by PI/6 radians clockwise: @example rotate=PI/6 @end example @item Rotate the input by PI/6 radians counter-clockwise: @example rotate=-PI/6 @end example @item Rotate the input by 45 degrees clockwise: @example rotate=45*PI/180 @end example @item Apply a constant rotation with period T, starting from an angle of PI/3: @example rotate=PI/3+2*PI*t/T @end example @item Make the input video rotation oscillating with a period of T seconds and an amplitude of A radians: @example rotate=A*sin(2*PI/T*t) @end example @item Rotate the video, output size is chosen so that the whole rotating input video is always completely contained in the output: @example rotate='2*PI*t:ow=hypot(iw,ih):oh=ow' @end example @item Rotate the video, reduce the output size so that no background is ever shown: @example rotate=2*PI*t:ow='min(iw,ih)/sqrt(2)':oh=ow:c=none @end example @end itemize @subsection Commands The filter supports the following commands: @table @option @item a, angle Set the angle expression. The command accepts the same syntax of the corresponding option. If the specified expression is not valid, it is kept at its current value. @end table @section sab Apply Shape Adaptive Blur. The filter accepts the following options: @table @option @item luma_radius, lr Set luma blur filter strength, must be a value in range 0.1-4.0, default value is 1.0. A greater value will result in a more blurred image, and in slower processing. @item luma_pre_filter_radius, lpfr Set luma pre-filter radius, must be a value in the 0.1-2.0 range, default value is 1.0. @item luma_strength, ls Set luma maximum difference between pixels to still be considered, must be a value in the 0.1-100.0 range, default value is 1.0. @item chroma_radius, cr Set chroma blur filter strength, must be a value in range 0.1-4.0. A greater value will result in a more blurred image, and in slower processing. @item chroma_pre_filter_radius, cpfr Set chroma pre-filter radius, must be a value in the 0.1-2.0 range. @item chroma_strength, cs Set chroma maximum difference between pixels to still be considered, must be a value in the 0.1-100.0 range. @end table Each chroma option value, if not explicitly specified, is set to the corresponding luma option value. @anchor{scale} @section scale Scale (resize) the input video, using the libswscale library. The scale filter forces the output display aspect ratio to be the same of the input, by changing the output sample aspect ratio. If the input image format is different from the format requested by the next filter, the scale filter will convert the input to the requested format. @subsection Options The filter accepts the following options, or any of the options supported by the libswscale scaler. See @ref{scaler_options,,the ffmpeg-scaler manual,ffmpeg-scaler} for the complete list of scaler options. @table @option @item width, w @item height, h Set the output video dimension expression. Default value is the input dimension. If the value is 0, the input width is used for the output. If one of the values is -1, the scale filter will use a value that maintains the aspect ratio of the input image, calculated from the other specified dimension. If both of them are -1, the input size is used If one of the values is -n with n > 1, the scale filter will also use a value that maintains the aspect ratio of the input image, calculated from the other specified dimension. After that it will, however, make sure that the calculated dimension is divisible by n and adjust the value if necessary. See below for the list of accepted constants for use in the dimension expression. @item interl Set the interlacing mode. It accepts the following values: @table @samp @item 1 Force interlaced aware scaling. @item 0 Do not apply interlaced scaling. @item -1 Select interlaced aware scaling depending on whether the source frames are flagged as interlaced or not. @end table Default value is @samp{0}. @item flags Set libswscale scaling flags. See @ref{sws_flags,,the ffmpeg-scaler manual,ffmpeg-scaler} for the complete list of values. If not explicitly specified the filter applies the default flags. @item size, s Set the video size. For the syntax of this option, check the "Video size" section in the ffmpeg-utils manual. @item in_color_matrix @item out_color_matrix Set in/output YCbCr color space type. This allows the autodetected value to be overridden as well as allows forcing a specific value used for the output and encoder. If not specified, the color space type depends on the pixel format. Possible values: @table @samp @item auto Choose automatically. @item bt709 Format conforming to International Telecommunication Union (ITU) Recommendation BT.709. @item fcc Set color space conforming to the United States Federal Communications Commission (FCC) Code of Federal Regulations (CFR) Title 47 (2003) 73.682 (a). @item bt601 Set color space conforming to: @itemize @item ITU Radiocommunication Sector (ITU-R) Recommendation BT.601 @item ITU-R Rec. BT.470-6 (1998) Systems B, B1, and G @item Society of Motion Picture and Television Engineers (SMPTE) ST 170:2004 @end itemize @item smpte240m Set color space conforming to SMPTE ST 240:1999. @end table @item in_range @item out_range Set in/output YCbCr sample range. This allows the autodetected value to be overridden as well as allows forcing a specific value used for the output and encoder. If not specified, the range depends on the pixel format. Possible values: @table @samp @item auto Choose automatically. @item jpeg/full/pc Set full range (0-255 in case of 8-bit luma). @item mpeg/tv Set "MPEG" range (16-235 in case of 8-bit luma). @end table @item force_original_aspect_ratio Enable decreasing or increasing output video width or height if necessary to keep the original aspect ratio. Possible values: @table @samp @item disable Scale the video as specified and disable this feature. @item decrease The output video dimensions will automatically be decreased if needed. @item increase The output video dimensions will automatically be increased if needed. @end table One useful instance of this option is that when you know a specific device's maximum allowed resolution, you can use this to limit the output video to that, while retaining the aspect ratio. For example, device A allows 1280x720 playback, and your video is 1920x800. Using this option (set it to decrease) and specifying 1280x720 to the command line makes the output 1280x533. Please note that this is a different thing than specifying -1 for @option{w} or @option{h}, you still need to specify the output resolution for this option to work. @end table The values of the @option{w} and @option{h} options are expressions containing the following constants: @table @var @item in_w @item in_h The input width and height @item iw @item ih These are the same as @var{in_w} and @var{in_h}. @item out_w @item out_h The output (scaled) width and height @item ow @item oh These are the same as @var{out_w} and @var{out_h} @item a The same as @var{iw} / @var{ih} @item sar input sample aspect ratio @item dar The input display aspect ratio. Calculated from @code{(iw / ih) * sar}. @item hsub @item vsub horizontal and vertical input chroma subsample values. For example for the pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. @item ohsub @item ovsub horizontal and vertical output chroma subsample values. For example for the pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. @end table @subsection Examples @itemize @item Scale the input video to a size of 200x100 @example scale=w=200:h=100 @end example This is equivalent to: @example scale=200:100 @end example or: @example scale=200x100 @end example @item Specify a size abbreviation for the output size: @example scale=qcif @end example which can also be written as: @example scale=size=qcif @end example @item Scale the input to 2x: @example scale=w=2*iw:h=2*ih @end example @item The above is the same as: @example scale=2*in_w:2*in_h @end example @item Scale the input to 2x with forced interlaced scaling: @example scale=2*iw:2*ih:interl=1 @end example @item Scale the input to half size: @example scale=w=iw/2:h=ih/2 @end example @item Increase the width, and set the height to the same size: @example scale=3/2*iw:ow @end example @item Seek Greek harmony: @example scale=iw:1/PHI*iw scale=ih*PHI:ih @end example @item Increase the height, and set the width to 3/2 of the height: @example scale=w=3/2*oh:h=3/5*ih @end example @item Increase the size, making the size a multiple of the chroma subsample values: @example scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub" @end example @item Increase the width to a maximum of 500 pixels, keeping the same aspect ratio as the input: @example scale=w='min(500\, iw*3/2):h=-1' @end example @end itemize @section separatefields The @code{separatefields} takes a frame-based video input and splits each frame into its components fields, producing a new half height clip with twice the frame rate and twice the frame count. This filter use field-dominance information in frame to decide which of each pair of fields to place first in the output. If it gets it wrong use @ref{setfield} filter before @code{separatefields} filter. @section setdar, setsar The @code{setdar} filter sets the Display Aspect Ratio for the filter output video. This is done by changing the specified Sample (aka Pixel) Aspect Ratio, according to the following equation: @example @var{DAR} = @var{HORIZONTAL_RESOLUTION} / @var{VERTICAL_RESOLUTION} * @var{SAR} @end example Keep in mind that the @code{setdar} filter does not modify the pixel dimensions of the video frame. Also, the display aspect ratio set by this filter may be changed by later filters in the filterchain, e.g. in case of scaling or if another "setdar" or a "setsar" filter is applied. The @code{setsar} filter sets the Sample (aka Pixel) Aspect Ratio for the filter output video. Note that as a consequence of the application of this filter, the output display aspect ratio will change according to the equation above. Keep in mind that the sample aspect ratio set by the @code{setsar} filter may be changed by later filters in the filterchain, e.g. if another "setsar" or a "setdar" filter is applied. It accepts the following parameters: @table @option @item r, ratio, dar (@code{setdar} only), sar (@code{setsar} only) Set the aspect ratio used by the filter. The parameter can be a floating point number string, an expression, or a string of the form @var{num}:@var{den}, where @var{num} and @var{den} are the numerator and denominator of the aspect ratio. If the parameter is not specified, it is assumed the value "0". In case the form "@var{num}:@var{den}" is used, the @code{:} character should be escaped. @item max Set the maximum integer value to use for expressing numerator and denominator when reducing the expressed aspect ratio to a rational. Default value is @code{100}. @end table The parameter @var{sar} is an expression containing the following constants: @table @option @item E, PI, PHI These are approximated values for the mathematical constants e (Euler's number), pi (Greek pi), and phi (the golden ratio). @item w, h The input width and height. @item a These are the same as @var{w} / @var{h}. @item sar The input sample aspect ratio. @item dar The input display aspect ratio. It is the same as (@var{w} / @var{h}) * @var{sar}. @item hsub, vsub Horizontal and vertical chroma subsample values. For example, for the pixel format "yuv422p" @var{hsub} is 2 and @var{vsub} is 1. @end table @subsection Examples @itemize @item To change the display aspect ratio to 16:9, specify one of the following: @example setdar=dar=1.77777 setdar=dar=16/9 setdar=dar=1.77777 @end example @item To change the sample aspect ratio to 10:11, specify: @example setsar=sar=10/11 @end example @item To set a display aspect ratio of 16:9, and specify a maximum integer value of 1000 in the aspect ratio reduction, use the command: @example setdar=ratio=16/9:max=1000 @end example @end itemize @anchor{setfield} @section setfield Force field for the output video frame. The @code{setfield} filter marks the interlace type field for the output frames. It does not change the input frame, but only sets the corresponding property, which affects how the frame is treated by following filters (e.g. @code{fieldorder} or @code{yadif}). The filter accepts the following options: @table @option @item mode Available values are: @table @samp @item auto Keep the same field property. @item bff Mark the frame as bottom-field-first. @item tff Mark the frame as top-field-first. @item prog Mark the frame as progressive. @end table @end table @section showinfo Show a line containing various information for each input video frame. The input video is not modified. The shown line contains a sequence of key/value pairs of the form @var{key}:@var{value}. The following values are shown in the output: @table @option @item n The (sequential) number of the input frame, starting from 0. @item pts The Presentation TimeStamp of the input frame, expressed as a number of time base units. The time base unit depends on the filter input pad. @item pts_time The Presentation TimeStamp of the input frame, expressed as a number of seconds. @item pos The position of the frame in the input stream, or -1 if this information is unavailable and/or meaningless (for example in case of synthetic video). @item fmt The pixel format name. @item sar The sample aspect ratio of the input frame, expressed in the form @var{num}/@var{den}. @item s The size of the input frame. For the syntax of this option, check the "Video size" section in the ffmpeg-utils manual. @item i The type of interlaced mode ("P" for "progressive", "T" for top field first, "B" for bottom field first). @item iskey This is 1 if the frame is a key frame, 0 otherwise. @item type The picture type of the input frame ("I" for an I-frame, "P" for a P-frame, "B" for a B-frame, or "?" for an unknown type). Also refer to the documentation of the @code{AVPictureType} enum and of the @code{av_get_picture_type_char} function defined in @file{libavutil/avutil.h}. @item checksum The Adler-32 checksum (printed in hexadecimal) of all the planes of the input frame. @item plane_checksum The Adler-32 checksum (printed in hexadecimal) of each plane of the input frame, expressed in the form "[@var{c0} @var{c1} @var{c2} @var{c3}]". @end table @section shuffleplanes Reorder and/or duplicate video planes. It accepts the following parameters: @table @option @item map0 The index of the input plane to be used as the first output plane. @item map1 The index of the input plane to be used as the second output plane. @item map2 The index of the input plane to be used as the third output plane. @item map3 The index of the input plane to be used as the fourth output plane. @end table The first plane has the index 0. The default is to keep the input unchanged. Swap the second and third planes of the input: @example ffmpeg -i INPUT -vf shuffleplanes=0:2:1:3 OUTPUT @end example @section signalstats Evaluate various visual metrics that assist in determining issues associated with the digitization of analog video media. By default the filter will log these metadata values: @table @option @item YMIN Display the minimal Y value contained within the input frame. Expressed in range of [0-255]. @item YLOW Display the Y value at the 10% percentile within the input frame. Expressed in range of [0-255]. @item YAVG Display the average Y value within the input frame. Expressed in range of [0-255]. @item YHIGH Display the Y value at the 90% percentile within the input frame. Expressed in range of [0-255]. @item YMAX Display the maximum Y value contained within the input frame. Expressed in range of [0-255]. @item UMIN Display the minimal U value contained within the input frame. Expressed in range of [0-255]. @item ULOW Display the U value at the 10% percentile within the input frame. Expressed in range of [0-255]. @item UAVG Display the average U value within the input frame. Expressed in range of [0-255]. @item UHIGH Display the U value at the 90% percentile within the input frame. Expressed in range of [0-255]. @item UMAX Display the maximum U value contained within the input frame. Expressed in range of [0-255]. @item VMIN Display the minimal V value contained within the input frame. Expressed in range of [0-255]. @item VLOW Display the V value at the 10% percentile within the input frame. Expressed in range of [0-255]. @item VAVG Display the average V value within the input frame. Expressed in range of [0-255]. @item VHIGH Display the V value at the 90% percentile within the input frame. Expressed in range of [0-255]. @item VMAX Display the maximum V value contained within the input frame. Expressed in range of [0-255]. @item SATMIN Display the minimal saturation value contained within the input frame. Expressed in range of [0-~181.02]. @item SATLOW Display the saturation value at the 10% percentile within the input frame. Expressed in range of [0-~181.02]. @item SATAVG Display the average saturation value within the input frame. Expressed in range of [0-~181.02]. @item SATHIGH Display the saturation value at the 90% percentile within the input frame. Expressed in range of [0-~181.02]. @item SATMAX Display the maximum saturation value contained within the input frame. Expressed in range of [0-~181.02]. @item HUEMED Display the median value for hue within the input frame. Expressed in range of [0-360]. @item HUEAVG Display the average value for hue within the input frame. Expressed in range of [0-360]. @item YDIF Display the average of sample value difference between all values of the Y plane in the current frame and corresponding values of the previous input frame. Expressed in range of [0-255]. @item UDIF Display the average of sample value difference between all values of the U plane in the current frame and corresponding values of the previous input frame. Expressed in range of [0-255]. @item VDIF Display the average of sample value difference between all values of the V plane in the current frame and corresponding values of the previous input frame. Expressed in range of [0-255]. @end table The filter accepts the following options: @table @option @item stat @item out @option{stat} specify an additional form of image analysis. @option{out} output video with the specified type of pixel highlighted. Both options accept the following values: @table @samp @item tout Identify @var{temporal outliers} pixels. A @var{temporal outlier} is a pixel unlike the neighboring pixels of the same field. Examples of temporal outliers include the results of video dropouts, head clogs, or tape tracking issues. @item vrep Identify @var{vertical line repetition}. Vertical line repetition includes similar rows of pixels within a frame. In born-digital video vertical line repetition is common, but this pattern is uncommon in video digitized from an analog source. When it occurs in video that results from the digitization of an analog source it can indicate concealment from a dropout compensator. @item brng Identify pixels that fall outside of legal broadcast range. @end table @item color, c Set the highlight color for the @option{out} option. The default color is yellow. @end table @subsection Examples @itemize @item Output data of various video metrics: @example ffprobe -f lavfi movie=example.mov,signalstats="stat=tout+vrep+brng" -show_frames @end example @item Output specific data about the minimum and maximum values of the Y plane per frame: @example ffprobe -f lavfi movie=example.mov,signalstats -show_entries frame_tags=lavfi.signalstats.YMAX,lavfi.signalstats.YMIN @end example @item Playback video while highlighting pixels that are outside of broadcast range in red. @example ffplay example.mov -vf signalstats="out=brng:color=red" @end example @item Playback video with signalstats metadata drawn over the frame. @example ffplay example.mov -vf signalstats=stat=brng+vrep+tout,drawtext=fontfile=FreeSerif.ttf:textfile=signalstat_drawtext.txt @end example The contents of signalstat_drawtext.txt used in the command are: @example time %@{pts:hms@} Y (%@{metadata:lavfi.signalstats.YMIN@}-%@{metadata:lavfi.signalstats.YMAX@}) U (%@{metadata:lavfi.signalstats.UMIN@}-%@{metadata:lavfi.signalstats.UMAX@}) V (%@{metadata:lavfi.signalstats.VMIN@}-%@{metadata:lavfi.signalstats.VMAX@}) saturation maximum: %@{metadata:lavfi.signalstats.SATMAX@} @end example @end itemize @anchor{smartblur} @section smartblur Blur the input video without impacting the outlines. It accepts the following options: @table @option @item luma_radius, lr Set the luma radius. The option value must be a float number in the range [0.1,5.0] that specifies the variance of the gaussian filter used to blur the image (slower if larger). Default value is 1.0. @item luma_strength, ls Set the luma strength. The option value must be a float number in the range [-1.0,1.0] that configures the blurring. A value included in [0.0,1.0] will blur the image whereas a value included in [-1.0,0.0] will sharpen the image. Default value is 1.0. @item luma_threshold, lt Set the luma threshold used as a coefficient to determine whether a pixel should be blurred or not. The option value must be an integer in the range [-30,30]. A value of 0 will filter all the image, a value included in [0,30] will filter flat areas and a value included in [-30,0] will filter edges. Default value is 0. @item chroma_radius, cr Set the chroma radius. The option value must be a float number in the range [0.1,5.0] that specifies the variance of the gaussian filter used to blur the image (slower if larger). Default value is 1.0. @item chroma_strength, cs Set the chroma strength. The option value must be a float number in the range [-1.0,1.0] that configures the blurring. A value included in [0.0,1.0] will blur the image whereas a value included in [-1.0,0.0] will sharpen the image. Default value is 1.0. @item chroma_threshold, ct Set the chroma threshold used as a coefficient to determine whether a pixel should be blurred or not. The option value must be an integer in the range [-30,30]. A value of 0 will filter all the image, a value included in [0,30] will filter flat areas and a value included in [-30,0] will filter edges. Default value is 0. @end table If a chroma option is not explicitly set, the corresponding luma value is set. @section stereo3d Convert between different stereoscopic image formats. The filters accept the following options: @table @option @item in Set stereoscopic image format of input. Available values for input image formats are: @table @samp @item sbsl side by side parallel (left eye left, right eye right) @item sbsr side by side crosseye (right eye left, left eye right) @item sbs2l side by side parallel with half width resolution (left eye left, right eye right) @item sbs2r side by side crosseye with half width resolution (right eye left, left eye right) @item abl above-below (left eye above, right eye below) @item abr above-below (right eye above, left eye below) @item ab2l above-below with half height resolution (left eye above, right eye below) @item ab2r above-below with half height resolution (right eye above, left eye below) @item al alternating frames (left eye first, right eye second) @item ar alternating frames (right eye first, left eye second) Default value is @samp{sbsl}. @end table @item out Set stereoscopic image format of output. Available values for output image formats are all the input formats as well as: @table @samp @item arbg anaglyph red/blue gray (red filter on left eye, blue filter on right eye) @item argg anaglyph red/green gray (red filter on left eye, green filter on right eye) @item arcg anaglyph red/cyan gray (red filter on left eye, cyan filter on right eye) @item arch anaglyph red/cyan half colored (red filter on left eye, cyan filter on right eye) @item arcc anaglyph red/cyan color (red filter on left eye, cyan filter on right eye) @item arcd anaglyph red/cyan color optimized with the least squares projection of dubois (red filter on left eye, cyan filter on right eye) @item agmg anaglyph green/magenta gray (green filter on left eye, magenta filter on right eye) @item agmh anaglyph green/magenta half colored (green filter on left eye, magenta filter on right eye) @item agmc anaglyph green/magenta colored (green filter on left eye, magenta filter on right eye) @item agmd anaglyph green/magenta color optimized with the least squares projection of dubois (green filter on left eye, magenta filter on right eye) @item aybg anaglyph yellow/blue gray (yellow filter on left eye, blue filter on right eye) @item aybh anaglyph yellow/blue half colored (yellow filter on left eye, blue filter on right eye) @item aybc anaglyph yellow/blue colored (yellow filter on left eye, blue filter on right eye) @item aybd anaglyph yellow/blue color optimized with the least squares projection of dubois (yellow filter on left eye, blue filter on right eye) @item irl interleaved rows (left eye has top row, right eye starts on next row) @item irr interleaved rows (right eye has top row, left eye starts on next row) @item ml mono output (left eye only) @item mr mono output (right eye only) @end table Default value is @samp{arcd}. @end table @subsection Examples @itemize @item Convert input video from side by side parallel to anaglyph yellow/blue dubois: @example stereo3d=sbsl:aybd @end example @item Convert input video from above bellow (left eye above, right eye below) to side by side crosseye. @example stereo3d=abl:sbsr @end example @end itemize @section spp Apply a simple postprocessing filter that compresses and decompresses the image at several (or - in the case of @option{quality} level @code{6} - all) shifts and average the results. The filter accepts the following options: @table @option @item quality Set quality. This option defines the number of levels for averaging. It accepts an integer in the range 0-6. If set to @code{0}, the filter will have no effect. A value of @code{6} means the higher quality. For each increment of that value the speed drops by a factor of approximately 2. Default value is @code{3}. @item qp Force a constant quantization parameter. If not set, the filter will use the QP from the video stream (if available). @item mode Set thresholding mode. Available modes are: @table @samp @item hard Set hard thresholding (default). @item soft Set soft thresholding (better de-ringing effect, but likely blurrier). @end table @item use_bframe_qp Enable the use of the QP from the B-Frames if set to @code{1}. Using this option may cause flicker since the B-Frames have often larger QP. Default is @code{0} (not enabled). @end table @anchor{subtitles} @section subtitles Draw subtitles on top of input video using the libass library. To enable compilation of this filter you need to configure FFmpeg with @code{--enable-libass}. This filter also requires a build with libavcodec and libavformat to convert the passed subtitles file to ASS (Advanced Substation Alpha) subtitles format. The filter accepts the following options: @table @option @item filename, f Set the filename of the subtitle file to read. It must be specified. @item original_size Specify the size of the original video, the video for which the ASS file was composed. For the syntax of this option, check the "Video size" section in the ffmpeg-utils manual. Due to a misdesign in ASS aspect ratio arithmetic, this is necessary to correctly scale the fonts if the aspect ratio has been changed. @item charenc Set subtitles input character encoding. @code{subtitles} filter only. Only useful if not UTF-8. @item stream_index, si Set subtitles stream index. @code{subtitles} filter only. @end table If the first key is not specified, it is assumed that the first value specifies the @option{filename}. For example, to render the file @file{sub.srt} on top of the input video, use the command: @example subtitles=sub.srt @end example which is equivalent to: @example subtitles=filename=sub.srt @end example To render the default subtitles stream from file @file{video.mkv}, use: @example subtitles=video.mkv @end example To render the second subtitles stream from that file, use: @example subtitles=video.mkv:si=1 @end example @section super2xsai Scale the input by 2x and smooth using the Super2xSaI (Scale and Interpolate) pixel art scaling algorithm. Useful for enlarging pixel art images without reducing sharpness. @section swapuv Swap U & V plane. @section telecine Apply telecine process to the video. This filter accepts the following options: @table @option @item first_field @table @samp @item top, t top field first @item bottom, b bottom field first The default value is @code{top}. @end table @item pattern A string of numbers representing the pulldown pattern you wish to apply. The default value is @code{23}. @end table @example Some typical patterns: NTSC output (30i): 27.5p: 32222 24p: 23 (classic) 24p: 2332 (preferred) 20p: 33 18p: 334 16p: 3444 PAL output (25i): 27.5p: 12222 24p: 222222222223 ("Euro pulldown") 16.67p: 33 16p: 33333334 @end example @section thumbnail Select the most representative frame in a given sequence of consecutive frames. The filter accepts the following options: @table @option @item n Set the frames batch size to analyze; in a set of @var{n} frames, the filter will pick one of them, and then handle the next batch of @var{n} frames until the end. Default is @code{100}. @end table Since the filter keeps track of the whole frames sequence, a bigger @var{n} value will result in a higher memory usage, so a high value is not recommended. @subsection Examples @itemize @item Extract one picture each 50 frames: @example thumbnail=50 @end example @item Complete example of a thumbnail creation with @command{ffmpeg}: @example ffmpeg -i in.avi -vf thumbnail,scale=300:200 -frames:v 1 out.png @end example @end itemize @section tile Tile several successive frames together. The filter accepts the following options: @table @option @item layout Set the grid size (i.e. the number of lines and columns). For the syntax of this option, check the "Video size" section in the ffmpeg-utils manual. @item nb_frames Set the maximum number of frames to render in the given area. It must be less than or equal to @var{w}x@var{h}. The default value is @code{0}, meaning all the area will be used. @item margin Set the outer border margin in pixels. @item padding Set the inner border thickness (i.e. the number of pixels between frames). For more advanced padding options (such as having different values for the edges), refer to the pad video filter. @item color Specify the color of the unused areaFor the syntax of this option, check the "Color" section in the ffmpeg-utils manual. The default value of @var{color} is "black". @end table @subsection Examples @itemize @item Produce 8x8 PNG tiles of all keyframes (@option{-skip_frame nokey}) in a movie: @example ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png @end example The @option{-vsync 0} is necessary to prevent @command{ffmpeg} from duplicating each output frame to accommodate the originally detected frame rate. @item Display @code{5} pictures in an area of @code{3x2} frames, with @code{7} pixels between them, and @code{2} pixels of initial margin, using mixed flat and named options: @example tile=3x2:nb_frames=5:padding=7:margin=2 @end example @end itemize @section tinterlace Perform various types of temporal field interlacing. Frames are counted starting from 1, so the first input frame is considered odd. The filter accepts the following options: @table @option @item mode Specify the mode of the interlacing. This option can also be specified as a value alone. See below for a list of values for this option. Available values are: @table @samp @item merge, 0 Move odd frames into the upper field, even into the lower field, generating a double height frame at half frame rate. @item drop_odd, 1 Only output even frames, odd frames are dropped, generating a frame with unchanged height at half frame rate. @item drop_even, 2 Only output odd frames, even frames are dropped, generating a frame with unchanged height at half frame rate. @item pad, 3 Expand each frame to full height, but pad alternate lines with black, generating a frame with double height at the same input frame rate. @item interleave_top, 4 Interleave the upper field from odd frames with the lower field from even frames, generating a frame with unchanged height at half frame rate. @item interleave_bottom, 5 Interleave the lower field from odd frames with the upper field from even frames, generating a frame with unchanged height at half frame rate. @item interlacex2, 6 Double frame rate with unchanged height. Frames are inserted each containing the second temporal field from the previous input frame and the first temporal field from the next input frame. This mode relies on the top_field_first flag. Useful for interlaced video displays with no field synchronisation. @end table Numeric values are deprecated but are accepted for backward compatibility reasons. Default mode is @code{merge}. @item flags Specify flags influencing the filter process. Available value for @var{flags} is: @table @option @item low_pass_filter, vlfp Enable vertical low-pass filtering in the filter. Vertical low-pass filtering is required when creating an interlaced destination from a progressive source which contains high-frequency vertical detail. Filtering will reduce interlace 'twitter' and Moire patterning. Vertical low-pass filtering can only be enabled for @option{mode} @var{interleave_top} and @var{interleave_bottom}. @end table @end table @section transpose Transpose rows with columns in the input video and optionally flip it. It accepts the following parameters: @table @option @item dir Specify the transposition direction. Can assume the following values: @table @samp @item 0, 4, cclock_flip Rotate by 90 degrees counterclockwise and vertically flip (default), that is: @example L.R L.l . . -> . . l.r R.r @end example @item 1, 5, clock Rotate by 90 degrees clockwise, that is: @example L.R l.L . . -> . . l.r r.R @end example @item 2, 6, cclock Rotate by 90 degrees counterclockwise, that is: @example L.R R.r . . -> . . l.r L.l @end example @item 3, 7, clock_flip Rotate by 90 degrees clockwise and vertically flip, that is: @example L.R r.R . . -> . . l.r l.L @end example @end table For values between 4-7, the transposition is only done if the input video geometry is portrait and not landscape. These values are deprecated, the @code{passthrough} option should be used instead. Numerical values are deprecated, and should be dropped in favor of symbolic constants. @item passthrough Do not apply the transposition if the input geometry matches the one specified by the specified value. It accepts the following values: @table @samp @item none Always apply transposition. @item portrait Preserve portrait geometry (when @var{height} >= @var{width}). @item landscape Preserve landscape geometry (when @var{width} >= @var{height}). @end table Default value is @code{none}. @end table For example to rotate by 90 degrees clockwise and preserve portrait layout: @example transpose=dir=1:passthrough=portrait @end example The command above can also be specified as: @example transpose=1:portrait @end example @section trim Trim the input so that the output contains one continuous subpart of the input. It accepts the following parameters: @table @option @item start Specify the time of the start of the kept section, i.e. the frame with the timestamp @var{start} will be the first frame in the output. @item end Specify the time of the first frame that will be dropped, i.e. the frame immediately preceding the one with the timestamp @var{end} will be the last frame in the output. @item start_pts This is the same as @var{start}, except this option sets the start timestamp in timebase units instead of seconds. @item end_pts This is the same as @var{end}, except this option sets the end timestamp in timebase units instead of seconds. @item duration The maximum duration of the output in seconds. @item start_frame The number of the first frame that should be passed to the output. @item end_frame The number of the first frame that should be dropped. @end table @option{start}, @option{end}, and @option{duration} are expressed as time duration specifications; see @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils} for the accepted syntax. Note that the first two sets of the start/end options and the @option{duration} option look at the frame timestamp, while the _frame variants simply count the frames that pass through the filter. Also note that this filter does not modify the timestamps. If you wish for the output timestamps to start at zero, insert a setpts filter after the trim filter. If multiple start or end options are set, this filter tries to be greedy and keep all the frames that match at least one of the specified constraints. To keep only the part that matches all the constraints at once, chain multiple trim filters. The defaults are such that all the input is kept. So it is possible to set e.g. just the end values to keep everything before the specified time. Examples: @itemize @item Drop everything except the second minute of input: @example ffmpeg -i INPUT -vf trim=60:120 @end example @item Keep only the first second: @example ffmpeg -i INPUT -vf trim=duration=1 @end example @end itemize @anchor{unsharp} @section unsharp Sharpen or blur the input video. It accepts the following parameters: @table @option @item luma_msize_x, lx Set the luma matrix horizontal size. It must be an odd integer between 3 and 63. The default value is 5. @item luma_msize_y, ly Set the luma matrix vertical size. It must be an odd integer between 3 and 63. The default value is 5. @item luma_amount, la Set the luma effect strength. It must be a floating point number, reasonable values lay between -1.5 and 1.5. Negative values will blur the input video, while positive values will sharpen it, a value of zero will disable the effect. Default value is 1.0. @item chroma_msize_x, cx Set the chroma matrix horizontal size. It must be an odd integer between 3 and 63. The default value is 5. @item chroma_msize_y, cy Set the chroma matrix vertical size. It must be an odd integer between 3 and 63. The default value is 5. @item chroma_amount, ca Set the chroma effect strength. It must be a floating point number, reasonable values lay between -1.5 and 1.5. Negative values will blur the input video, while positive values will sharpen it, a value of zero will disable the effect. Default value is 0.0. @item opencl If set to 1, specify using OpenCL capabilities, only available if FFmpeg was configured with @code{--enable-opencl}. Default value is 0. @end table All parameters are optional and default to the equivalent of the string '5:5:1.0:5:5:0.0'. @subsection Examples @itemize @item Apply strong luma sharpen effect: @example unsharp=luma_msize_x=7:luma_msize_y=7:luma_amount=2.5 @end example @item Apply a strong blur of both luma and chroma parameters: @example unsharp=7:7:-2:7:7:-2 @end example @end itemize @anchor{vidstabdetect} @section vidstabdetect Analyze video stabilization/deshaking. Perform pass 1 of 2, see @ref{vidstabtransform} for pass 2. This filter generates a file with relative translation and rotation transform information about subsequent frames, which is then used by the @ref{vidstabtransform} filter. To enable compilation of this filter you need to configure FFmpeg with @code{--enable-libvidstab}. This filter accepts the following options: @table @option @item result Set the path to the file used to write the transforms information. Default value is @file{transforms.trf}. @item shakiness Set how shaky the video is and how quick the camera is. It accepts an integer in the range 1-10, a value of 1 means little shakiness, a value of 10 means strong shakiness. Default value is 5. @item accuracy Set the accuracy of the detection process. It must be a value in the range 1-15. A value of 1 means low accuracy, a value of 15 means high accuracy. Default value is 15. @item stepsize Set stepsize of the search process. The region around minimum is scanned with 1 pixel resolution. Default value is 6. @item mincontrast Set minimum contrast. Below this value a local measurement field is discarded. Must be a floating point value in the range 0-1. Default value is 0.3. @item tripod Set reference frame number for tripod mode. If enabled, the motion of the frames is compared to a reference frame in the filtered stream, identified by the specified number. The idea is to compensate all movements in a more-or-less static scene and keep the camera view absolutely still. If set to 0, it is disabled. The frames are counted starting from 1. @item show Show fields and transforms in the resulting frames. It accepts an integer in the range 0-2. Default value is 0, which disables any visualization. @end table @subsection Examples @itemize @item Use default values: @example vidstabdetect @end example @item Analyze strongly shaky movie and put the results in file @file{mytransforms.trf}: @example vidstabdetect=shakiness=10:accuracy=15:result="mytransforms.trf" @end example @item Visualize the result of internal transformations in the resulting video: @example vidstabdetect=show=1 @end example @item Analyze a video with medium shakiness using @command{ffmpeg}: @example ffmpeg -i input -vf vidstabdetect=shakiness=5:show=1 dummy.avi @end example @end itemize @anchor{vidstabtransform} @section vidstabtransform Video stabilization/deshaking: pass 2 of 2, see @ref{vidstabdetect} for pass 1. Read a file with transform information for each frame and apply/compensate them. Together with the @ref{vidstabdetect} filter this can be used to deshake videos. See also @url{http://public.hronopik.de/vid.stab}. It is important to also use the @ref{unsharp} filter, see below. To enable compilation of this filter you need to configure FFmpeg with @code{--enable-libvidstab}. @subsection Options @table @option @item input Set path to the file used to read the transforms. Default value is @file{transforms.trf}. @item smoothing Set the number of frames (value*2 + 1) used for lowpass filtering the camera movements. Default value is 10. For example a number of 10 means that 21 frames are used (10 in the past and 10 in the future) to smoothen the motion in the video. A larger value leads to a smoother video, but limits the acceleration of the camera (pan/tilt movements). 0 is a special case where a static camera is simulated. @item optalgo Set the camera path optimization algorithm. Accepted values are: @table @samp @item gauss gaussian kernel low-pass filter on camera motion (default) @item avg averaging on transformations @end table @item maxshift Set maximal number of pixels to translate frames. Default value is -1, meaning no limit. @item maxangle Set maximal angle in radians (degree*PI/180) to rotate frames. Default value is -1, meaning no limit. @item crop Specify how to deal with borders that may be visible due to movement compensation. Available values are: @table @samp @item keep keep image information from previous frame (default) @item black fill the border black @end table @item invert Invert transforms if set to 1. Default value is 0. @item relative Consider transforms as relative to previous frame if set to 1, absolute if set to 0. Default value is 0. @item zoom Set percentage to zoom. A positive value will result in a zoom-in effect, a negative value in a zoom-out effect. Default value is 0 (no zoom). @item optzoom Set optimal zooming to avoid borders. Accepted values are: @table @samp @item 0 disabled @item 1 optimal static zoom value is determined (only very strong movements will lead to visible borders) (default) @item 2 optimal adaptive zoom value is determined (no borders will be visible), see @option{zoomspeed} @end table Note that the value given at zoom is added to the one calculated here. @item zoomspeed Set percent to zoom maximally each frame (enabled when @option{optzoom} is set to 2). Range is from 0 to 5, default value is 0.25. @item interpol Specify type of interpolation. Available values are: @table @samp @item no no interpolation @item linear linear only horizontal @item bilinear linear in both directions (default) @item bicubic cubic in both directions (slow) @end table @item tripod Enable virtual tripod mode if set to 1, which is equivalent to @code{relative=0:smoothing=0}. Default value is 0. Use also @code{tripod} option of @ref{vidstabdetect}. @item debug Increase log verbosity if set to 1. Also the detected global motions are written to the temporary file @file{global_motions.trf}. Default value is 0. @end table @subsection Examples @itemize @item Use @command{ffmpeg} for a typical stabilization with default values: @example ffmpeg -i inp.mpeg -vf vidstabtransform,unsharp=5:5:0.8:3:3:0.4 inp_stabilized.mpeg @end example Note the use of the @ref{unsharp} filter which is always recommended. @item Zoom in a bit more and load transform data from a given file: @example vidstabtransform=zoom=5:input="mytransforms.trf" @end example @item Smoothen the video even more: @example vidstabtransform=smoothing=30 @end example @end itemize @section vflip Flip the input video vertically. For example, to vertically flip a video with @command{ffmpeg}: @example ffmpeg -i in.avi -vf "vflip" out.avi @end example @anchor{vignette} @section vignette Make or reverse a natural vignetting effect. The filter accepts the following options: @table @option @item angle, a Set lens angle expression as a number of radians. The value is clipped in the @code{[0,PI/2]} range. Default value: @code{"PI/5"} @item x0 @item y0 Set center coordinates expressions. Respectively @code{"w/2"} and @code{"h/2"} by default. @item mode Set forward/backward mode. Available modes are: @table @samp @item forward The larger the distance from the central point, the darker the image becomes. @item backward The larger the distance from the central point, the brighter the image becomes. This can be used to reverse a vignette effect, though there is no automatic detection to extract the lens @option{angle} and other settings (yet). It can also be used to create a burning effect. @end table Default value is @samp{forward}. @item eval Set evaluation mode for the expressions (@option{angle}, @option{x0}, @option{y0}). It accepts the following values: @table @samp @item init Evaluate expressions only once during the filter initialization. @item frame Evaluate expressions for each incoming frame. This is way slower than the @samp{init} mode since it requires all the scalers to be re-computed, but it allows advanced dynamic expressions. @end table Default value is @samp{init}. @item dither Set dithering to reduce the circular banding effects. Default is @code{1} (enabled). @item aspect Set vignette aspect. This setting allows one to adjust the shape of the vignette. Setting this value to the SAR of the input will make a rectangular vignetting following the dimensions of the video. Default is @code{1/1}. @end table @subsection Expressions The @option{alpha}, @option{x0} and @option{y0} expressions can contain the following parameters. @table @option @item w @item h input width and height @item n the number of input frame, starting from 0 @item pts the PTS (Presentation TimeStamp) time of the filtered video frame, expressed in @var{TB} units, NAN if undefined @item r frame rate of the input video, NAN if the input frame rate is unknown @item t the PTS (Presentation TimeStamp) of the filtered video frame, expressed in seconds, NAN if undefined @item tb time base of the input video @end table @subsection Examples @itemize @item Apply simple strong vignetting effect: @example vignette=PI/4 @end example @item Make a flickering vignetting: @example vignette='PI/4+random(1)*PI/50':eval=frame @end example @end itemize @section w3fdif Deinterlace the input video ("w3fdif" stands for "Weston 3 Field Deinterlacing Filter"). Based on the process described by Martin Weston for BBC R&D, and implemented based on the de-interlace algorithm written by Jim Easterbrook for BBC R&D, the Weston 3 field deinterlacing filter uses filter coefficients calculated by BBC R&D. There are two sets of filter coefficients, so called "simple": and "complex". Which set of filter coefficients is used can be set by passing an optional parameter: @table @option @item filter Set the interlacing filter coefficients. Accepts one of the following values: @table @samp @item simple Simple filter coefficient set. @item complex More-complex filter coefficient set. @end table Default value is @samp{complex}. @item deint Specify which frames to deinterlace. Accept one of the following values: @table @samp @item all Deinterlace all frames, @item interlaced Only deinterlace frames marked as interlaced. @end table Default value is @samp{all}. @end table @section xbr Apply the xBR high-quality magnification filter which is designed for pixel art. It follows a set of edge-detection rules, see @url{http://www.libretro.com/forums/viewtopic.php?f=6&t=134}. It accepts the following option: @table @option @item n Set the scaling dimension: @code{2} for @code{2xBR}, @code{3} for @code{3xBR} and @code{4} for @code{4xBR}. Default is @code{3}. @end table @anchor{yadif} @section yadif Deinterlace the input video ("yadif" means "yet another deinterlacing filter"). It accepts the following parameters: @table @option @item mode The interlacing mode to adopt. It accepts one of the following values: @table @option @item 0, send_frame Output one frame for each frame. @item 1, send_field Output one frame for each field. @item 2, send_frame_nospatial Like @code{send_frame}, but it skips the spatial interlacing check. @item 3, send_field_nospatial Like @code{send_field}, but it skips the spatial interlacing check. @end table The default value is @code{send_frame}. @item parity The picture field parity assumed for the input interlaced video. It accepts one of the following values: @table @option @item 0, tff Assume the top field is first. @item 1, bff Assume the bottom field is first. @item -1, auto Enable automatic detection of field parity. @end table The default value is @code{auto}. If the interlacing is unknown or the decoder does not export this information, top field first will be assumed. @item deint Specify which frames to deinterlace. Accept one of the following values: @table @option @item 0, all Deinterlace all frames. @item 1, interlaced Only deinterlace frames marked as interlaced. @end table The default value is @code{all}. @end table @section zoompan Apply Zoom & Pan effect. This filter accepts the following options: @table @option @item zoom, z Set the zoom expression. Default is 1. @item x @item y Set the x and y expression. Default is 0. @item d Set the duration expression in number of frames. This sets for how many number of frames effect will last for single input image. @item s Set the output image size, default is 'hd720'. @end table Each expression can contain the following constants: @table @option @item in_w, iw Input width. @item in_h, ih Input height. @item out_w, ow Output width. @item out_h, oh Output height. @item in Input frame count. @item on Output frame count. @item x @item y Last calculated 'x' and 'y' position from 'x' and 'y' expression for current input frame. @item px @item py 'x' and 'y' of last output frame of previous input frame or 0 when there was not yet such frame (first input frame). @item zoom Last calculated zoom from 'z' expression for current input frame. @item pzoom Last calculated zoom of last output frame of previous input frame. @item duration Number of output frames for current input frame. Calculated from 'd' expression for each input frame. @item pduration number of output frames created for previous input frame @item a Rational number: input width / input height @item sar sample aspect ratio @item dar display aspect ratio @end table @subsection Examples @itemize @item Zoom-in up to 1.5 and pan at same time to some spot near center of picture: @example zoompan=z='min(zoom+0.0015,1.5)':d=700:x='if(gte(zoom,1.5),x,x+1/a)':y='if(gte(zoom,1.5),y,y+1)':s=640x360 @end example @end itemize @c man end VIDEO FILTERS @chapter Video Sources @c man begin VIDEO SOURCES Below is a description of the currently available video sources. @section buffer Buffer video frames, and make them available to the filter chain. This source is mainly intended for a programmatic use, in particular through the interface defined in @file{libavfilter/vsrc_buffer.h}. It accepts the following parameters: @table @option @item video_size Specify the size (width and height) of the buffered video frames. For the syntax of this option, check the "Video size" section in the ffmpeg-utils manual. @item width The input video width. @item height The input video height. @item pix_fmt A string representing the pixel format of the buffered video frames. It may be a number corresponding to a pixel format, or a pixel format name. @item time_base Specify the timebase assumed by the timestamps of the buffered frames. @item frame_rate Specify the frame rate expected for the video stream. @item pixel_aspect, sar The sample (pixel) aspect ratio of the input video. @item sws_param Specify the optional parameters to be used for the scale filter which is automatically inserted when an input change is detected in the input size or format. @end table For example: @example buffer=width=320:height=240:pix_fmt=yuv410p:time_base=1/24:sar=1 @end example will instruct the source to accept video frames with size 320x240 and with format "yuv410p", assuming 1/24 as the timestamps timebase and square pixels (1:1 sample aspect ratio). Since the pixel format with name "yuv410p" corresponds to the number 6 (check the enum AVPixelFormat definition in @file{libavutil/pixfmt.h}), this example corresponds to: @example buffer=size=320x240:pixfmt=6:time_base=1/24:pixel_aspect=1/1 @end example Alternatively, the options can be specified as a flat string, but this syntax is deprecated: @var{width}:@var{height}:@var{pix_fmt}:@var{time_base.num}:@var{time_base.den}:@var{pixel_aspect.num}:@var{pixel_aspect.den}[:@var{sws_param}] @section cellauto Create a pattern generated by an elementary cellular automaton. The initial state of the cellular automaton can be defined through the @option{filename}, and @option{pattern} options. If such options are not specified an initial state is created randomly. At each new frame a new row in the video is filled with the result of the cellular automaton next generation. The behavior when the whole frame is filled is defined by the @option{scroll} option. This source accepts the following options: @table @option @item filename, f Read the initial cellular automaton state, i.e. the starting row, from the specified file. In the file, each non-whitespace character is considered an alive cell, a newline will terminate the row, and further characters in the file will be ignored. @item pattern, p Read the initial cellular automaton state, i.e. the starting row, from the specified string. Each non-whitespace character in the string is considered an alive cell, a newline will terminate the row, and further characters in the string will be ignored. @item rate, r Set the video rate, that is the number of frames generated per second. Default is 25. @item random_fill_ratio, ratio Set the random fill ratio for the initial cellular automaton row. It is a floating point number value ranging from 0 to 1, defaults to 1/PHI. This option is ignored when a file or a pattern is specified. @item random_seed, seed Set the seed for filling randomly the initial row, must be an integer included between 0 and UINT32_MAX. If not specified, or if explicitly set to -1, the filter will try to use a good random seed on a best effort basis. @item rule Set the cellular automaton rule, it is a number ranging from 0 to 255. Default value is 110. @item size, s Set the size of the output video. For the syntax of this option, check the "Video size" section in the ffmpeg-utils manual. If @option{filename} or @option{pattern} is specified, the size is set by default to the width of the specified initial state row, and the height is set to @var{width} * PHI. If @option{size} is set, it must contain the width of the specified pattern string, and the specified pattern will be centered in the larger row. If a filename or a pattern string is not specified, the size value defaults to "320x518" (used for a randomly generated initial state). @item scroll If set to 1, scroll the output upward when all the rows in the output have been already filled. If set to 0, the new generated row will be written over the top row just after the bottom row is filled. Defaults to 1. @item start_full, full If set to 1, completely fill the output with generated rows before outputting the first frame. This is the default behavior, for disabling set the value to 0. @item stitch If set to 1, stitch the left and right row edges together. This is the default behavior, for disabling set the value to 0. @end table @subsection Examples @itemize @item Read the initial state from @file{pattern}, and specify an output of size 200x400. @example cellauto=f=pattern:s=200x400 @end example @item Generate a random initial row with a width of 200 cells, with a fill ratio of 2/3: @example cellauto=ratio=2/3:s=200x200 @end example @item Create a pattern generated by rule 18 starting by a single alive cell centered on an initial row with width 100: @example cellauto=p=@@:s=100x400:full=0:rule=18 @end example @item Specify a more elaborated initial pattern: @example cellauto=p='@@@@ @@ @@@@':s=100x400:full=0:rule=18 @end example @end itemize @section mandelbrot Generate a Mandelbrot set fractal, and progressively zoom towards the point specified with @var{start_x} and @var{start_y}. This source accepts the following options: @table @option @item end_pts Set the terminal pts value. Default value is 400. @item end_scale Set the terminal scale value. Must be a floating point value. Default value is 0.3. @item inner Set the inner coloring mode, that is the algorithm used to draw the Mandelbrot fractal internal region. It shall assume one of the following values: @table @option @item black Set black mode. @item convergence Show time until convergence. @item mincol Set color based on point closest to the origin of the iterations. @item period Set period mode. @end table Default value is @var{mincol}. @item bailout Set the bailout value. Default value is 10.0. @item maxiter Set the maximum of iterations performed by the rendering algorithm. Default value is 7189. @item outer Set outer coloring mode. It shall assume one of following values: @table @option @item iteration_count Set iteration cound mode. @item normalized_iteration_count set normalized iteration count mode. @end table Default value is @var{normalized_iteration_count}. @item rate, r Set frame rate, expressed as number of frames per second. Default value is "25". @item size, s Set frame size. For the syntax of this option, check the "Video size" section in the ffmpeg-utils manual. Default value is "640x480". @item start_scale Set the initial scale value. Default value is 3.0. @item start_x Set the initial x position. Must be a floating point value between -100 and 100. Default value is -0.743643887037158704752191506114774. @item start_y Set the initial y position. Must be a floating point value between -100 and 100. Default value is -0.131825904205311970493132056385139. @end table @section mptestsrc Generate various test patterns, as generated by the MPlayer test filter. The size of the generated video is fixed, and is 256x256. This source is useful in particular for testing encoding features. This source accepts the following options: @table @option @item rate, r Specify the frame rate of the sourced video, as the number of frames generated per second. It has to be a string in the format @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point number or a valid video frame rate abbreviation. The default value is "25". @item duration, d Set the duration of the sourced video. See @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils} for the accepted syntax. If not specified, or the expressed duration is negative, the video is supposed to be generated forever. @item test, t Set the number or the name of the test to perform. Supported tests are: @table @option @item dc_luma @item dc_chroma @item freq_luma @item freq_chroma @item amp_luma @item amp_chroma @item cbp @item mv @item ring1 @item ring2 @item all @end table Default value is "all", which will cycle through the list of all tests. @end table Some examples: @example mptestsrc=t=dc_luma @end example will generate a "dc_luma" test pattern. @section frei0r_src Provide a frei0r source. To enable compilation of this filter you need to install the frei0r header and configure FFmpeg with @code{--enable-frei0r}. This source accepts the following parameters: @table @option @item size The size of the video to generate. For the syntax of this option, check the "Video size" section in the ffmpeg-utils manual. @item framerate The framerate of the generated video. It may be a string of the form @var{num}/@var{den} or a frame rate abbreviation. @item filter_name The name to the frei0r source to load. For more information regarding frei0r and how to set the parameters, read the @ref{frei0r} section in the video filters documentation. @item filter_params A '|'-separated list of parameters to pass to the frei0r source. @end table For example, to generate a frei0r partik0l source with size 200x200 and frame rate 10 which is overlayed on the overlay filter main input: @example frei0r_src=size=200x200:framerate=10:filter_name=partik0l:filter_params=1234 [overlay]; [in][overlay] overlay @end example @section life Generate a life pattern. This source is based on a generalization of John Conway's life game. The sourced input represents a life grid, each pixel represents a cell which can be in one of two possible states, alive or dead. Every cell interacts with its eight neighbours, which are the cells that are horizontally, vertically, or diagonally adjacent. At each interaction the grid evolves according to the adopted rule, which specifies the number of neighbor alive cells which will make a cell stay alive or born. The @option{rule} option allows one to specify the rule to adopt. This source accepts the following options: @table @option @item filename, f Set the file from which to read the initial grid state. In the file, each non-whitespace character is considered an alive cell, and newline is used to delimit the end of each row. If this option is not specified, the initial grid is generated randomly. @item rate, r Set the video rate, that is the number of frames generated per second. Default is 25. @item random_fill_ratio, ratio Set the random fill ratio for the initial random grid. It is a floating point number value ranging from 0 to 1, defaults to 1/PHI. It is ignored when a file is specified. @item random_seed, seed Set the seed for filling the initial random grid, must be an integer included between 0 and UINT32_MAX. If not specified, or if explicitly set to -1, the filter will try to use a good random seed on a best effort basis. @item rule Set the life rule. A rule can be specified with a code of the kind "S@var{NS}/B@var{NB}", where @var{NS} and @var{NB} are sequences of numbers in the range 0-8, @var{NS} specifies the number of alive neighbor cells which make a live cell stay alive, and @var{NB} the number of alive neighbor cells which make a dead cell to become alive (i.e. to "born"). "s" and "b" can be used in place of "S" and "B", respectively. Alternatively a rule can be specified by an 18-bits integer. The 9 high order bits are used to encode the next cell state if it is alive for each number of neighbor alive cells, the low order bits specify the rule for "borning" new cells. Higher order bits encode for an higher number of neighbor cells. For example the number 6153 = @code{(12<<9)+9} specifies a stay alive rule of 12 and a born rule of 9, which corresponds to "S23/B03". Default value is "S23/B3", which is the original Conway's game of life rule, and will keep a cell alive if it has 2 or 3 neighbor alive cells, and will born a new cell if there are three alive cells around a dead cell. @item size, s Set the size of the output video. For the syntax of this option, check the "Video size" section in the ffmpeg-utils manual. If @option{filename} is specified, the size is set by default to the same size of the input file. If @option{size} is set, it must contain the size specified in the input file, and the initial grid defined in that file is centered in the larger resulting area. If a filename is not specified, the size value defaults to "320x240" (used for a randomly generated initial grid). @item stitch If set to 1, stitch the left and right grid edges together, and the top and bottom edges also. Defaults to 1. @item mold Set cell mold speed. If set, a dead cell will go from @option{death_color} to @option{mold_color} with a step of @option{mold}. @option{mold} can have a value from 0 to 255. @item life_color Set the color of living (or new born) cells. @item death_color Set the color of dead cells. If @option{mold} is set, this is the first color used to represent a dead cell. @item mold_color Set mold color, for definitely dead and moldy cells. For the syntax of these 3 color options, check the "Color" section in the ffmpeg-utils manual. @end table @subsection Examples @itemize @item Read a grid from @file{pattern}, and center it on a grid of size 300x300 pixels: @example life=f=pattern:s=300x300 @end example @item Generate a random grid of size 200x200, with a fill ratio of 2/3: @example life=ratio=2/3:s=200x200 @end example @item Specify a custom rule for evolving a randomly generated grid: @example life=rule=S14/B34 @end example @item Full example with slow death effect (mold) using @command{ffplay}: @example ffplay -f lavfi life=s=300x200:mold=10:r=60:ratio=0.1:death_color=#C83232:life_color=#00ff00,scale=1200:800:flags=16 @end example @end itemize @anchor{color} @anchor{haldclutsrc} @anchor{nullsrc} @anchor{rgbtestsrc} @anchor{smptebars} @anchor{smptehdbars} @anchor{testsrc} @section color, haldclutsrc, nullsrc, rgbtestsrc, smptebars, smptehdbars, testsrc The @code{color} source provides an uniformly colored input. The @code{haldclutsrc} source provides an identity Hald CLUT. See also @ref{haldclut} filter. The @code{nullsrc} source returns unprocessed video frames. It is mainly useful to be employed in analysis / debugging tools, or as the source for filters which ignore the input data. The @code{rgbtestsrc} source generates an RGB test pattern useful for detecting RGB vs BGR issues. You should see a red, green and blue stripe from top to bottom. The @code{smptebars} source generates a color bars pattern, based on the SMPTE Engineering Guideline EG 1-1990. The @code{smptehdbars} source generates a color bars pattern, based on the SMPTE RP 219-2002. The @code{testsrc} source generates a test video pattern, showing a color pattern, a scrolling gradient and a timestamp. This is mainly intended for testing purposes. The sources accept the following parameters: @table @option @item color, c Specify the color of the source, only available in the @code{color} source. For the syntax of this option, check the "Color" section in the ffmpeg-utils manual. @item level Specify the level of the Hald CLUT, only available in the @code{haldclutsrc} source. A level of @code{N} generates a picture of @code{N*N*N} by @code{N*N*N} pixels to be used as identity matrix for 3D lookup tables. Each component is coded on a @code{1/(N*N)} scale. @item size, s Specify the size of the sourced video. For the syntax of this option, check the "Video size" section in the ffmpeg-utils manual. The default value is "320x240". This option is not available with the @code{haldclutsrc} filter. @item rate, r Specify the frame rate of the sourced video, as the number of frames generated per second. It has to be a string in the format @var{frame_rate_num}/@var{frame_rate_den}, an integer number, a floating point number or a valid video frame rate abbreviation. The default value is "25". @item sar Set the sample aspect ratio of the sourced video. @item duration, d Set the duration of the sourced video. See @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils} for the accepted syntax. If not specified, or the expressed duration is negative, the video is supposed to be generated forever. @item decimals, n Set the number of decimals to show in the timestamp, only available in the @code{testsrc} source. The displayed timestamp value will correspond to the original timestamp value multiplied by the power of 10 of the specified value. Default value is 0. @end table For example the following: @example testsrc=duration=5.3:size=qcif:rate=10 @end example will generate a video with a duration of 5.3 seconds, with size 176x144 and a frame rate of 10 frames per second. The following graph description will generate a red source with an opacity of 0.2, with size "qcif" and a frame rate of 10 frames per second. @example color=c=red@@0.2:s=qcif:r=10 @end example If the input content is to be ignored, @code{nullsrc} can be used. The following command generates noise in the luminance plane by employing the @code{geq} filter: @example nullsrc=s=256x256, geq=random(1)*255:128:128 @end example @subsection Commands The @code{color} source supports the following commands: @table @option @item c, color Set the color of the created image. Accepts the same syntax of the corresponding @option{color} option. @end table @c man end VIDEO SOURCES @chapter Video Sinks @c man begin VIDEO SINKS Below is a description of the currently available video sinks. @section buffersink Buffer video frames, and make them available to the end of the filter graph. This sink is mainly intended for programmatic use, in particular through the interface defined in @file{libavfilter/buffersink.h} or the options system. It accepts a pointer to an AVBufferSinkContext structure, which defines the incoming buffers' formats, to be passed as the opaque parameter to @code{avfilter_init_filter} for initialization. @section nullsink Null video sink: do absolutely nothing with the input video. It is mainly useful as a template and for use in analysis / debugging tools. @c man end VIDEO SINKS @chapter Multimedia Filters @c man begin MULTIMEDIA FILTERS Below is a description of the currently available multimedia filters. @section avectorscope Convert input audio to a video output, representing the audio vector scope. The filter is used to measure the difference between channels of stereo audio stream. A monoaural signal, consisting of identical left and right signal, results in straight vertical line. Any stereo separation is visible as a deviation from this line, creating a Lissajous figure. If the straight (or deviation from it) but horizontal line appears this indicates that the left and right channels are out of phase. The filter accepts the following options: @table @option @item mode, m Set the vectorscope mode. Available values are: @table @samp @item lissajous Lissajous rotated by 45 degrees. @item lissajous_xy Same as above but not rotated. @end table Default value is @samp{lissajous}. @item size, s Set the video size for the output. For the syntax of this option, check the "Video size" section in the ffmpeg-utils manual. Default value is @code{400x400}. @item rate, r Set the output frame rate. Default value is @code{25}. @item rc @item gc @item bc Specify the red, green and blue contrast. Default values are @code{40}, @code{160} and @code{80}. Allowed range is @code{[0, 255]}. @item rf @item gf @item bf Specify the red, green and blue fade. Default values are @code{15}, @code{10} and @code{5}. Allowed range is @code{[0, 255]}. @item zoom Set the zoom factor. Default value is @code{1}. Allowed range is @code{[1, 10]}. @end table @subsection Examples @itemize @item Complete example using @command{ffplay}: @example ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1]; [a] avectorscope=zoom=1.3:rc=2:gc=200:bc=10:rf=1:gf=8:bf=7 [out0]' @end example @end itemize @section concat Concatenate audio and video streams, joining them together one after the other. The filter works on segments of synchronized video and audio streams. All segments must have the same number of streams of each type, and that will also be the number of streams at output. The filter accepts the following options: @table @option @item n Set the number of segments. Default is 2. @item v Set the number of output video streams, that is also the number of video streams in each segment. Default is 1. @item a Set the number of output audio streams, that is also the number of audio streams in each segment. Default is 0. @item unsafe Activate unsafe mode: do not fail if segments have a different format. @end table The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then @var{a} audio outputs. There are @var{n}x(@var{v}+@var{a}) inputs: first the inputs for the first segment, in the same order as the outputs, then the inputs for the second segment, etc. Related streams do not always have exactly the same duration, for various reasons including codec frame size or sloppy authoring. For that reason, related synchronized streams (e.g. a video and its audio track) should be concatenated at once. The concat filter will use the duration of the longest stream in each segment (except the last one), and if necessary pad shorter audio streams with silence. For this filter to work correctly, all segments must start at timestamp 0. All corresponding streams must have the same parameters in all segments; the filtering system will automatically select a common pixel format for video streams, and a common sample format, sample rate and channel layout for audio streams, but other settings, such as resolution, must be converted explicitly by the user. Different frame rates are acceptable but will result in variable frame rate at output; be sure to configure the output file to handle it. @subsection Examples @itemize @item Concatenate an opening, an episode and an ending, all in bilingual version (video in stream 0, audio in streams 1 and 2): @example ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \ '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2] concat=n=3:v=1:a=2 [v] [a1] [a2]' \ -map '[v]' -map '[a1]' -map '[a2]' output.mkv @end example @item Concatenate two parts, handling audio and video separately, using the (a)movie sources, and adjusting the resolution: @example movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ; movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ; [v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa] @end example Note that a desync will happen at the stitch if the audio and video streams do not have exactly the same duration in the first file. @end itemize @section ebur128 EBU R128 scanner filter. This filter takes an audio stream as input and outputs it unchanged. By default, it logs a message at a frequency of 10Hz with the Momentary loudness (identified by @code{M}), Short-term loudness (@code{S}), Integrated loudness (@code{I}) and Loudness Range (@code{LRA}). The filter also has a video output (see the @var{video} option) with a real time graph to observe the loudness evolution. The graphic contains the logged message mentioned above, so it is not printed anymore when this option is set, unless the verbose logging is set. The main graphing area contains the short-term loudness (3 seconds of analysis), and the gauge on the right is for the momentary loudness (400 milliseconds). More information about the Loudness Recommendation EBU R128 on @url{http://tech.ebu.ch/loudness}. The filter accepts the following options: @table @option @item video Activate the video output. The audio stream is passed unchanged whether this option is set or no. The video stream will be the first output stream if activated. Default is @code{0}. @item size Set the video size. This option is for video only. For the syntax of this option, check the "Video size" section in the ffmpeg-utils manual. Default and minimum resolution is @code{640x480}. @item meter Set the EBU scale meter. Default is @code{9}. Common values are @code{9} and @code{18}, respectively for EBU scale meter +9 and EBU scale meter +18. Any other integer value between this range is allowed. @item metadata Set metadata injection. If set to @code{1}, the audio input will be segmented into 100ms output frames, each of them containing various loudness information in metadata. All the metadata keys are prefixed with @code{lavfi.r128.}. Default is @code{0}. @item framelog Force the frame logging level. Available values are: @table @samp @item info information logging level @item verbose verbose logging level @end table By default, the logging level is set to @var{info}. If the @option{video} or the @option{metadata} options are set, it switches to @var{verbose}. @item peak Set peak mode(s). Available modes can be cumulated (the option is a @code{flag} type). Possible values are: @table @samp @item none Disable any peak mode (default). @item sample Enable sample-peak mode. Simple peak mode looking for the higher sample value. It logs a message for sample-peak (identified by @code{SPK}). @item true Enable true-peak mode. If enabled, the peak lookup is done on an over-sampled version of the input stream for better peak accuracy. It logs a message for true-peak. (identified by @code{TPK}) and true-peak per frame (identified by @code{FTPK}). This mode requires a build with @code{libswresample}. @end table @end table @subsection Examples @itemize @item Real-time graph using @command{ffplay}, with a EBU scale meter +18: @example ffplay -f lavfi -i "amovie=input.mp3,ebur128=video=1:meter=18 [out0][out1]" @end example @item Run an analysis with @command{ffmpeg}: @example ffmpeg -nostats -i input.mp3 -filter_complex ebur128 -f null - @end example @end itemize @section interleave, ainterleave Temporally interleave frames from several inputs. @code{interleave} works with video inputs, @code{ainterleave} with audio. These filters read frames from several inputs and send the oldest queued frame to the output. Input streams must have a well defined, monotonically increasing frame timestamp values. In order to submit one frame to output, these filters need to enqueue at least one frame for each input, so they cannot work in case one input is not yet terminated and will not receive incoming frames. For example consider the case when one input is a @code{select} filter which always drop input frames. The @code{interleave} filter will keep reading from that input, but it will never be able to send new frames to output until the input will send an end-of-stream signal. Also, depending on inputs synchronization, the filters will drop frames in case one input receives more frames than the other ones, and the queue is already filled. These filters accept the following options: @table @option @item nb_inputs, n Set the number of different inputs, it is 2 by default. @end table @subsection Examples @itemize @item Interleave frames belonging to different streams using @command{ffmpeg}: @example ffmpeg -i bambi.avi -i pr0n.mkv -filter_complex "[0:v][1:v] interleave" out.avi @end example @item Add flickering blur effect: @example select='if(gt(random(0), 0.2), 1, 2)':n=2 [tmp], boxblur=2:2, [tmp] interleave @end example @end itemize @section perms, aperms Set read/write permissions for the output frames. These filters are mainly aimed at developers to test direct path in the following filter in the filtergraph. The filters accept the following options: @table @option @item mode Select the permissions mode. It accepts the following values: @table @samp @item none Do nothing. This is the default. @item ro Set all the output frames read-only. @item rw Set all the output frames directly writable. @item toggle Make the frame read-only if writable, and writable if read-only. @item random Set each output frame read-only or writable randomly. @end table @item seed Set the seed for the @var{random} mode, must be an integer included between @code{0} and @code{UINT32_MAX}. If not specified, or if explicitly set to @code{-1}, the filter will try to use a good random seed on a best effort basis. @end table Note: in case of auto-inserted filter between the permission filter and the following one, the permission might not be received as expected in that following filter. Inserting a @ref{format} or @ref{aformat} filter before the perms/aperms filter can avoid this problem. @section select, aselect Select frames to pass in output. This filter accepts the following options: @table @option @item expr, e Set expression, which is evaluated for each input frame. If the expression is evaluated to zero, the frame is discarded. If the evaluation result is negative or NaN, the frame is sent to the first output; otherwise it is sent to the output with index @code{ceil(val)-1}, assuming that the input index starts from 0. For example a value of @code{1.2} corresponds to the output with index @code{ceil(1.2)-1 = 2-1 = 1}, that is the second output. @item outputs, n Set the number of outputs. The output to which to send the selected frame is based on the result of the evaluation. Default value is 1. @end table The expression can contain the following constants: @table @option @item n The (sequential) number of the filtered frame, starting from 0. @item selected_n The (sequential) number of the selected frame, starting from 0. @item prev_selected_n The sequential number of the last selected frame. It's NAN if undefined. @item TB The timebase of the input timestamps. @item pts The PTS (Presentation TimeStamp) of the filtered video frame, expressed in @var{TB} units. It's NAN if undefined. @item t The PTS of the filtered video frame, expressed in seconds. It's NAN if undefined. @item prev_pts The PTS of the previously filtered video frame. It's NAN if undefined. @item prev_selected_pts The PTS of the last previously filtered video frame. It's NAN if undefined. @item prev_selected_t The PTS of the last previously selected video frame. It's NAN if undefined. @item start_pts The PTS of the first video frame in the video. It's NAN if undefined. @item start_t The time of the first video frame in the video. It's NAN if undefined. @item pict_type @emph{(video only)} The type of the filtered frame. It can assume one of the following values: @table @option @item I @item P @item B @item S @item SI @item SP @item BI @end table @item interlace_type @emph{(video only)} The frame interlace type. It can assume one of the following values: @table @option @item PROGRESSIVE The frame is progressive (not interlaced). @item TOPFIRST The frame is top-field-first. @item BOTTOMFIRST The frame is bottom-field-first. @end table @item consumed_sample_n @emph{(audio only)} the number of selected samples before the current frame @item samples_n @emph{(audio only)} the number of samples in the current frame @item sample_rate @emph{(audio only)} the input sample rate @item key This is 1 if the filtered frame is a key-frame, 0 otherwise. @item pos the position in the file of the filtered frame, -1 if the information is not available (e.g. for synthetic video) @item scene @emph{(video only)} value between 0 and 1 to indicate a new scene; a low value reflects a low probability for the current frame to introduce a new scene, while a higher value means the current frame is more likely to be one (see the example below) @end table The default value of the select expression is "1". @subsection Examples @itemize @item Select all frames in input: @example select @end example The example above is the same as: @example select=1 @end example @item Skip all frames: @example select=0 @end example @item Select only I-frames: @example select='eq(pict_type\,I)' @end example @item Select one frame every 100: @example select='not(mod(n\,100))' @end example @item Select only frames contained in the 10-20 time interval: @example select=between(t\,10\,20) @end example @item Select only I frames contained in the 10-20 time interval: @example select=between(t\,10\,20)*eq(pict_type\,I) @end example @item Select frames with a minimum distance of 10 seconds: @example select='isnan(prev_selected_t)+gte(t-prev_selected_t\,10)' @end example @item Use aselect to select only audio frames with samples number > 100: @example aselect='gt(samples_n\,100)' @end example @item Create a mosaic of the first scenes: @example ffmpeg -i video.avi -vf select='gt(scene\,0.4)',scale=160:120,tile -frames:v 1 preview.png @end example Comparing @var{scene} against a value between 0.3 and 0.5 is generally a sane choice. @item Send even and odd frames to separate outputs, and compose them: @example select=n=2:e='mod(n, 2)+1' [odd][even]; [odd] pad=h=2*ih [tmp]; [tmp][even] overlay=y=h @end example @end itemize @section sendcmd, asendcmd Send commands to filters in the filtergraph. These filters read commands to be sent to other filters in the filtergraph. @code{sendcmd} must be inserted between two video filters, @code{asendcmd} must be inserted between two audio filters, but apart from that they act the same way. The specification of commands can be provided in the filter arguments with the @var{commands} option, or in a file specified by the @var{filename} option. These filters accept the following options: @table @option @item commands, c Set the commands to be read and sent to the other filters. @item filename, f Set the filename of the commands to be read and sent to the other filters. @end table @subsection Commands syntax A commands description consists of a sequence of interval specifications, comprising a list of commands to be executed when a particular event related to that interval occurs. The occurring event is typically the current frame time entering or leaving a given time interval. An interval is specified by the following syntax: @example @var{START}[-@var{END}] @var{COMMANDS}; @end example The time interval is specified by the @var{START} and @var{END} times. @var{END} is optional and defaults to the maximum time. The current frame time is considered within the specified interval if it is included in the interval [@var{START}, @var{END}), that is when the time is greater or equal to @var{START} and is lesser than @var{END}. @var{COMMANDS} consists of a sequence of one or more command specifications, separated by ",", relating to that interval. The syntax of a command specification is given by: @example [@var{FLAGS}] @var{TARGET} @var{COMMAND} @var{ARG} @end example @var{FLAGS} is optional and specifies the type of events relating to the time interval which enable sending the specified command, and must be a non-null sequence of identifier flags separated by "+" or "|" and enclosed between "[" and "]". The following flags are recognized: @table @option @item enter The command is sent when the current frame timestamp enters the specified interval. In other words, the command is sent when the previous frame timestamp was not in the given interval, and the current is. @item leave The command is sent when the current frame timestamp leaves the specified interval. In other words, the command is sent when the previous frame timestamp was in the given interval, and the current is not. @end table If @var{FLAGS} is not specified, a default value of @code{[enter]} is assumed. @var{TARGET} specifies the target of the command, usually the name of the filter class or a specific filter instance name. @var{COMMAND} specifies the name of the command for the target filter. @var{ARG} is optional and specifies the optional list of argument for the given @var{COMMAND}. Between one interval specification and another, whitespaces, or sequences of characters starting with @code{#} until the end of line, are ignored and can be used to annotate comments. A simplified BNF description of the commands specification syntax follows: @example @var{COMMAND_FLAG} ::= "enter" | "leave" @var{COMMAND_FLAGS} ::= @var{COMMAND_FLAG} [(+|"|")@var{COMMAND_FLAG}] @var{COMMAND} ::= ["[" @var{COMMAND_FLAGS} "]"] @var{TARGET} @var{COMMAND} [@var{ARG}] @var{COMMANDS} ::= @var{COMMAND} [,@var{COMMANDS}] @var{INTERVAL} ::= @var{START}[-@var{END}] @var{COMMANDS} @var{INTERVALS} ::= @var{INTERVAL}[;@var{INTERVALS}] @end example @subsection Examples @itemize @item Specify audio tempo change at second 4: @example asendcmd=c='4.0 atempo tempo 1.5',atempo @end example @item Specify a list of drawtext and hue commands in a file. @example # show text in the interval 5-10 5.0-10.0 [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=hello world', [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text='; # desaturate the image in the interval 15-20 15.0-20.0 [enter] hue s 0, [enter] drawtext reinit 'fontfile=FreeSerif.ttf:text=nocolor', [leave] hue s 1, [leave] drawtext reinit 'fontfile=FreeSerif.ttf:text=color'; # apply an exponential saturation fade-out effect, starting from time 25 25 [enter] hue s exp(25-t) @end example A filtergraph allowing to read and process the above command list stored in a file @file{test.cmd}, can be specified with: @example sendcmd=f=test.cmd,drawtext=fontfile=FreeSerif.ttf:text='',hue @end example @end itemize @anchor{setpts} @section setpts, asetpts Change the PTS (presentation timestamp) of the input frames. @code{setpts} works on video frames, @code{asetpts} on audio frames. This filter accepts the following options: @table @option @item expr The expression which is evaluated for each frame to construct its timestamp. @end table The expression is evaluated through the eval API and can contain the following constants: @table @option @item FRAME_RATE frame rate, only defined for constant frame-rate video @item PTS The presentation timestamp in input @item N The count of the input frame for video or the number of consumed samples, not including the current frame for audio, starting from 0. @item NB_CONSUMED_SAMPLES The number of consumed samples, not including the current frame (only audio) @item NB_SAMPLES, S The number of samples in the current frame (only audio) @item SAMPLE_RATE, SR The audio sample rate. @item STARTPTS The PTS of the first frame. @item STARTT the time in seconds of the first frame @item INTERLACED State whether the current frame is interlaced. @item T the time in seconds of the current frame @item POS original position in the file of the frame, or undefined if undefined for the current frame @item PREV_INPTS The previous input PTS. @item PREV_INT previous input time in seconds @item PREV_OUTPTS The previous output PTS. @item PREV_OUTT previous output time in seconds @item RTCTIME The wallclock (RTC) time in microseconds.. This is deprecated, use time(0) instead. @item RTCSTART The wallclock (RTC) time at the start of the movie in microseconds. @item TB The timebase of the input timestamps. @end table @subsection Examples @itemize @item Start counting PTS from zero @example setpts=PTS-STARTPTS @end example @item Apply fast motion effect: @example setpts=0.5*PTS @end example @item Apply slow motion effect: @example setpts=2.0*PTS @end example @item Set fixed rate of 25 frames per second: @example setpts=N/(25*TB) @end example @item Set fixed rate 25 fps with some jitter: @example setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))' @end example @item Apply an offset of 10 seconds to the input PTS: @example setpts=PTS+10/TB @end example @item Generate timestamps from a "live source" and rebase onto the current timebase: @example setpts='(RTCTIME - RTCSTART) / (TB * 1000000)' @end example @item Generate timestamps by counting samples: @example asetpts=N/SR/TB @end example @end itemize @section settb, asettb Set the timebase to use for the output frames timestamps. It is mainly useful for testing timebase configuration. It accepts the following parameters: @table @option @item expr, tb The expression which is evaluated into the output timebase. @end table The value for @option{tb} is an arithmetic expression representing a rational. The expression can contain the constants "AVTB" (the default timebase), "intb" (the input timebase) and "sr" (the sample rate, audio only). Default value is "intb". @subsection Examples @itemize @item Set the timebase to 1/25: @example settb=expr=1/25 @end example @item Set the timebase to 1/10: @example settb=expr=0.1 @end example @item Set the timebase to 1001/1000: @example settb=1+0.001 @end example @item Set the timebase to 2*intb: @example settb=2*intb @end example @item Set the default timebase value: @example settb=AVTB @end example @end itemize @section showcqt Convert input audio to a video output representing frequency spectrum logarithmically (using constant Q transform with Brown-Puckette algorithm), with musical tone scale, from E0 to D#10 (10 octaves). The filter accepts the following options: @table @option @item volume Specify transform volume (multiplier) expression. The expression can contain variables: @table @option @item frequency, freq, f the frequency where transform is evaluated @item timeclamp, tc value of timeclamp option @end table and functions: @table @option @item a_weighting(f) A-weighting of equal loudness @item b_weighting(f) B-weighting of equal loudness @item c_weighting(f) C-weighting of equal loudness @end table Default value is @code{16}. @item tlength Specify transform length expression. The expression can contain variables: @table @option @item frequency, freq, f the frequency where transform is evaluated @item timeclamp, tc value of timeclamp option @end table Default value is @code{384/f*tc/(384/f+tc)}. @item timeclamp Specify the transform timeclamp. At low frequency, there is trade-off between accuracy in time domain and frequency domain. If timeclamp is lower, event in time domain is represented more accurately (such as fast bass drum), otherwise event in frequency domain is represented more accurately (such as bass guitar). Acceptable value is [0.1, 1.0]. Default value is @code{0.17}. @item coeffclamp Specify the transform coeffclamp. If coeffclamp is lower, transform is more accurate, otherwise transform is faster. Acceptable value is [0.1, 10.0]. Default value is @code{1.0}. @item gamma Specify gamma. Lower gamma makes the spectrum more contrast, higher gamma makes the spectrum having more range. Acceptable value is [1.0, 7.0]. Default value is @code{3.0}. @item fontfile Specify font file for use with freetype. If not specified, use embedded font. @item fontcolor Specify font color expression. This is arithmetic expression that should return integer value 0xRRGGBB. The expression can contain variables: @table @option @item frequency, freq, f the frequency where transform is evaluated @item timeclamp, tc value of timeclamp option @end table and functions: @table @option @item midi(f) midi number of frequency f, some midi numbers: E0(16), C1(24), C2(36), A4(69) @item r(x), g(x), b(x) red, green, and blue value of intensity x @end table Default value is @code{st(0, (midi(f)-59.5)/12); st(1, if(between(ld(0),0,1), 0.5-0.5*cos(2*PI*ld(0)), 0)); r(1-ld(1)) + b(ld(1))} @item fullhd If set to 1 (the default), the video size is 1920x1080 (full HD), if set to 0, the video size is 960x540. Use this option to make CPU usage lower. @item fps Specify video fps. Default value is @code{25}. @item count Specify number of transform per frame, so there are fps*count transforms per second. Note that audio data rate must be divisible by fps*count. Default value is @code{6}. @end table @subsection Examples @itemize @item Playing audio while showing the spectrum: @example ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt [out0]' @end example @item Same as above, but with frame rate 30 fps: @example ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=fps=30:count=5 [out0]' @end example @item Playing at 960x540 and lower CPU usage: @example ffplay -f lavfi 'amovie=a.mp3, asplit [a][out1]; [a] showcqt=fullhd=0:count=3 [out0]' @end example @item A1 and its harmonics: A1, A2, (near)E3, A3: @example ffplay -f lavfi 'aevalsrc=0.1*sin(2*PI*55*t)+0.1*sin(4*PI*55*t)+0.1*sin(6*PI*55*t)+0.1*sin(8*PI*55*t), asplit[a][out1]; [a] showcqt [out0]' @end example @item Same as above, but with more accuracy in frequency domain (and slower): @example ffplay -f lavfi 'aevalsrc=0.1*sin(2*PI*55*t)+0.1*sin(4*PI*55*t)+0.1*sin(6*PI*55*t)+0.1*sin(8*PI*55*t), asplit[a][out1]; [a] showcqt=timeclamp=0.5 [out0]' @end example @item B-weighting of equal loudness @example volume=16*b_weighting(f) @end example @item Lower Q factor @example tlength=100/f*tc/(100/f+tc) @end example @item Custom fontcolor, C-note is colored green, others are colored blue @example fontcolor='if(mod(floor(midi(f)+0.5),12), 0x0000FF, g(1))' @end example @end itemize @section showspectrum Convert input audio to a video output, representing the audio frequency spectrum. The filter accepts the following options: @table @option @item size, s Specify the video size for the output. For the syntax of this option, check the "Video size" section in the ffmpeg-utils manual. Default value is @code{640x512}. @item slide Specify how the spectrum should slide along the window. It accepts the following values: @table @samp @item replace the samples start again on the left when they reach the right @item scroll the samples scroll from right to left @item fullframe frames are only produced when the samples reach the right @end table Default value is @code{replace}. @item mode Specify display mode. It accepts the following values: @table @samp @item combined all channels are displayed in the same row @item separate all channels are displayed in separate rows @end table Default value is @samp{combined}. @item color Specify display color mode. It accepts the following values: @table @samp @item channel each channel is displayed in a separate color @item intensity each channel is is displayed using the same color scheme @end table Default value is @samp{channel}. @item scale Specify scale used for calculating intensity color values. It accepts the following values: @table @samp @item lin linear @item sqrt square root, default @item cbrt cubic root @item log logarithmic @end table Default value is @samp{sqrt}. @item saturation Set saturation modifier for displayed colors. Negative values provide alternative color scheme. @code{0} is no saturation at all. Saturation must be in [-10.0, 10.0] range. Default value is @code{1}. @item win_func Set window function. It accepts the following values: @table @samp @item none No samples pre-processing (do not expect this to be faster) @item hann Hann window @item hamming Hamming window @item blackman Blackman window @end table Default value is @code{hann}. @end table The usage is very similar to the showwaves filter; see the examples in that section. @subsection Examples @itemize @item Large window with logarithmic color scaling: @example showspectrum=s=1280x480:scale=log @end example @item Complete example for a colored and sliding spectrum per channel using @command{ffplay}: @example ffplay -f lavfi 'amovie=input.mp3, asplit [a][out1]; [a] showspectrum=mode=separate:color=intensity:slide=1:scale=cbrt [out0]' @end example @end itemize @section showwaves Convert input audio to a video output, representing the samples waves. The filter accepts the following options: @table @option @item size, s Specify the video size for the output. For the syntax of this option, check the "Video size" section in the ffmpeg-utils manual. Default value is "600x240". @item mode Set display mode. Available values are: @table @samp @item point Draw a point for each sample. @item line Draw a vertical line for each sample. @item p2p Draw a point for each sample and a line between them. @item cline Draw a centered vertical line for each sample. @end table Default value is @code{point}. @item n Set the number of samples which are printed on the same column. A larger value will decrease the frame rate. Must be a positive integer. This option can be set only if the value for @var{rate} is not explicitly specified. @item rate, r Set the (approximate) output frame rate. This is done by setting the option @var{n}. Default value is "25". @item split_channels Set if channels should be drawn separately or overlap. Default value is 0. @end table @subsection Examples @itemize @item Output the input file audio and the corresponding video representation at the same time: @example amovie=a.mp3,asplit[out0],showwaves[out1] @end example @item Create a synthetic signal and show it with showwaves, forcing a frame rate of 30 frames per second: @example aevalsrc=sin(1*2*PI*t)*sin(880*2*PI*t):cos(2*PI*200*t),asplit[out0],showwaves=r=30[out1] @end example @end itemize @section split, asplit Split input into several identical outputs. @code{asplit} works with audio input, @code{split} with video. The filter accepts a single parameter which specifies the number of outputs. If unspecified, it defaults to 2. @subsection Examples @itemize @item Create two separate outputs from the same input: @example [in] split [out0][out1] @end example @item To create 3 or more outputs, you need to specify the number of outputs, like in: @example [in] asplit=3 [out0][out1][out2] @end example @item Create two separate outputs from the same input, one cropped and one padded: @example [in] split [splitout1][splitout2]; [splitout1] crop=100:100:0:0 [cropout]; [splitout2] pad=200:200:100:100 [padout]; @end example @item Create 5 copies of the input audio with @command{ffmpeg}: @example ffmpeg -i INPUT -filter_complex asplit=5 OUTPUT @end example @end itemize @section zmq, azmq Receive commands sent through a libzmq client, and forward them to filters in the filtergraph. @code{zmq} and @code{azmq} work as a pass-through filters. @code{zmq} must be inserted between two video filters, @code{azmq} between two audio filters. To enable these filters you need to install the libzmq library and headers and configure FFmpeg with @code{--enable-libzmq}. For more information about libzmq see: @url{http://www.zeromq.org/} The @code{zmq} and @code{azmq} filters work as a libzmq server, which receives messages sent through a network interface defined by the @option{bind_address} option. The received message must be in the form: @example @var{TARGET} @var{COMMAND} [@var{ARG}] @end example @var{TARGET} specifies the target of the command, usually the name of the filter class or a specific filter instance name. @var{COMMAND} specifies the name of the command for the target filter. @var{ARG} is optional and specifies the optional argument list for the given @var{COMMAND}. Upon reception, the message is processed and the corresponding command is injected into the filtergraph. Depending on the result, the filter will send a reply to the client, adopting the format: @example @var{ERROR_CODE} @var{ERROR_REASON} @var{MESSAGE} @end example @var{MESSAGE} is optional. @subsection Examples Look at @file{tools/zmqsend} for an example of a zmq client which can be used to send commands processed by these filters. Consider the following filtergraph generated by @command{ffplay} @example ffplay -dumpgraph 1 -f lavfi " color=s=100x100:c=red [l]; color=s=100x100:c=blue [r]; nullsrc=s=200x100, zmq [bg]; [bg][l] overlay [bg+l]; [bg+l][r] overlay=x=100 " @end example To change the color of the left side of the video, the following command can be used: @example echo Parsed_color_0 c yellow | tools/zmqsend @end example To change the right side: @example echo Parsed_color_1 c pink | tools/zmqsend @end example @c man end MULTIMEDIA FILTERS @chapter Multimedia Sources @c man begin MULTIMEDIA SOURCES Below is a description of the currently available multimedia sources. @section amovie This is the same as @ref{movie} source, except it selects an audio stream by default. @anchor{movie} @section movie Read audio and/or video stream(s) from a movie container. It accepts the following parameters: @table @option @item filename The name of the resource to read (not necessarily a file; it can also be a device or a stream accessed through some protocol). @item format_name, f Specifies the format assumed for the movie to read, and can be either the name of a container or an input device. If not specified, the format is guessed from @var{movie_name} or by probing. @item seek_point, sp Specifies the seek point in seconds. The frames will be output starting from this seek point. The parameter is evaluated with @code{av_strtod}, so the numerical value may be suffixed by an IS postfix. The default value is "0". @item streams, s Specifies the streams to read. Several streams can be specified, separated by "+". The source will then have as many outputs, in the same order. The syntax is explained in the ``Stream specifiers'' section in the ffmpeg manual. Two special names, "dv" and "da" specify respectively the default (best suited) video and audio stream. Default is "dv", or "da" if the filter is called as "amovie". @item stream_index, si Specifies the index of the video stream to read. If the value is -1, the most suitable video stream will be automatically selected. The default value is "-1". Deprecated. If the filter is called "amovie", it will select audio instead of video. @item loop Specifies how many times to read the stream in sequence. If the value is less than 1, the stream will be read again and again. Default value is "1". Note that when the movie is looped the source timestamps are not changed, so it will generate non monotonically increasing timestamps. @end table It allows overlaying a second video on top of the main input of a filtergraph, as shown in this graph: @example input -----------> deltapts0 --> overlay --> output ^ | movie --> scale--> deltapts1 -------+ @end example @subsection Examples @itemize @item Skip 3.2 seconds from the start of the AVI file in.avi, and overlay it on top of the input labelled "in": @example movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [over]; [in] setpts=PTS-STARTPTS [main]; [main][over] overlay=16:16 [out] @end example @item Read from a video4linux2 device, and overlay it on top of the input labelled "in": @example movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [over]; [in] setpts=PTS-STARTPTS [main]; [main][over] overlay=16:16 [out] @end example @item Read the first video stream and the audio stream with id 0x81 from dvd.vob; the video is connected to the pad named "video" and the audio is connected to the pad named "audio": @example movie=dvd.vob:s=v:0+#0x81 [video] [audio] @end example @end itemize @c man end MULTIMEDIA SOURCES