mirror of https://git.ffmpeg.org/ffmpeg.git
1460 lines
56 KiB
Plaintext
1460 lines
56 KiB
Plaintext
\input texinfo @c -*- texinfo -*-
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@settitle ffmpeg Documentation
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@titlepage
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@center @titlefont{ffmpeg Documentation}
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@end titlepage
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@top
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@contents
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@chapter Synopsis
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ffmpeg [@var{global_options}] @{[@var{input_file_options}] -i @file{input_file}@} ... @{[@var{output_file_options}] @file{output_file}@} ...
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@chapter Description
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@c man begin DESCRIPTION
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@command{ffmpeg} is a very fast video and audio converter that can also grab from
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a live audio/video source. It can also convert between arbitrary sample
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rates and resize video on the fly with a high quality polyphase filter.
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@command{ffmpeg} reads from an arbitrary number of input "files" (which can be regular
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files, pipes, network streams, grabbing devices, etc.), specified by the
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@code{-i} option, and writes to an arbitrary number of output "files", which are
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specified by a plain output filename. Anything found on the command line which
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cannot be interpreted as an option is considered to be an output filename.
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Each input or output file can, in principle, contain any number of streams of
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different types (video/audio/subtitle/attachment/data). The allowed number and/or
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types of streams may be limited by the container format. Selecting which
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streams from which inputs will go into which output is either done automatically
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or with the @code{-map} option (see the Stream selection chapter).
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To refer to input files in options, you must use their indices (0-based). E.g.
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the first input file is @code{0}, the second is @code{1}, etc. Similarly, streams
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within a file are referred to by their indices. E.g. @code{2:3} refers to the
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fourth stream in the third input file. Also see the Stream specifiers chapter.
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As a general rule, options are applied to the next specified
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file. Therefore, order is important, and you can have the same
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option on the command line multiple times. Each occurrence is
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then applied to the next input or output file.
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Exceptions from this rule are the global options (e.g. verbosity level),
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which should be specified first.
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Do not mix input and output files -- first specify all input files, then all
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output files. Also do not mix options which belong to different files. All
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options apply ONLY to the next input or output file and are reset between files.
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@itemize
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@item
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To set the video bitrate of the output file to 64 kbit/s:
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@example
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ffmpeg -i input.avi -b:v 64k -bufsize 64k output.avi
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@end example
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@item
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To force the frame rate of the output file to 24 fps:
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@example
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ffmpeg -i input.avi -r 24 output.avi
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@end example
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@item
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To force the frame rate of the input file (valid for raw formats only)
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to 1 fps and the frame rate of the output file to 24 fps:
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@example
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ffmpeg -r 1 -i input.m2v -r 24 output.avi
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@end example
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@end itemize
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The format option may be needed for raw input files.
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@c man end DESCRIPTION
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@chapter Detailed description
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@c man begin DETAILED DESCRIPTION
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The transcoding process in @command{ffmpeg} for each output can be described by
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the following diagram:
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@example
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_______ ______________ _________ ______________ ________
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| | | | | | | | | |
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| input | demuxer | encoded data | decoder | decoded | encoder | encoded data | muxer | output |
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| file | ---------> | packets | ---------> | frames | ---------> | packets | -------> | file |
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|_______| |______________| |_________| |______________| |________|
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@end example
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@command{ffmpeg} calls the libavformat library (containing demuxers) to read
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input files and get packets containing encoded data from them. When there are
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multiple input files, @command{ffmpeg} tries to keep them synchronized by
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tracking lowest timestamp on any active input stream.
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Encoded packets are then passed to the decoder (unless streamcopy is selected
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for the stream, see further for a description). The decoder produces
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uncompressed frames (raw video/PCM audio/...) which can be processed further by
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filtering (see next section). After filtering, the frames are passed to the
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encoder, which encodes them and outputs encoded packets. Finally those are
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passed to the muxer, which writes the encoded packets to the output file.
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@section Filtering
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Before encoding, @command{ffmpeg} can process raw audio and video frames using
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filters from the libavfilter library. Several chained filters form a filter
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graph. @command{ffmpeg} distinguishes between two types of filtergraphs:
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simple and complex.
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@subsection Simple filtergraphs
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Simple filtergraphs are those that have exactly one input and output, both of
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the same type. In the above diagram they can be represented by simply inserting
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an additional step between decoding and encoding:
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@example
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_________ __________ ______________
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| | | | | |
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| decoded | simple filtergraph | filtered | encoder | encoded data |
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| frames | -------------------> | frames | ---------> | packets |
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|_________| |__________| |______________|
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@end example
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Simple filtergraphs are configured with the per-stream @option{-filter} option
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(with @option{-vf} and @option{-af} aliases for video and audio respectively).
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A simple filtergraph for video can look for example like this:
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@example
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_______ _____________ _______ _____ ________
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| | | | | | | | | |
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| input | ---> | deinterlace | ---> | scale | ---> | fps | ---> | output |
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|_______| |_____________| |_______| |_____| |________|
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@end example
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Note that some filters change frame properties but not frame contents. E.g. the
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@code{fps} filter in the example above changes number of frames, but does not
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touch the frame contents. Another example is the @code{setpts} filter, which
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only sets timestamps and otherwise passes the frames unchanged.
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@subsection Complex filtergraphs
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Complex filtergraphs are those which cannot be described as simply a linear
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processing chain applied to one stream. This is the case, for example, when the graph has
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more than one input and/or output, or when output stream type is different from
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input. They can be represented with the following diagram:
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@example
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_________
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| input 0 |\ __________
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|_________| \ | |
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\ _________ /| output 0 |
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\ | | / |__________|
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_________ \| complex | /
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| | | |/
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| input 1 |---->| filter |\
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|_________| | | \ __________
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/| graph | \ | |
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/ | | \| output 1 |
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_________ / |_________| |__________|
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| | /
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| input 2 |/
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|_________|
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@end example
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Complex filtergraphs are configured with the @option{-filter_complex} option.
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Note that this option is global, since a complex filtergraph, by its nature,
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cannot be unambiguously associated with a single stream or file.
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The @option{-lavfi} option is equivalent to @option{-filter_complex}.
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A trivial example of a complex filtergraph is the @code{overlay} filter, which
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has two video inputs and one video output, containing one video overlaid on top
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of the other. Its audio counterpart is the @code{amix} filter.
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@section Stream copy
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Stream copy is a mode selected by supplying the @code{copy} parameter to the
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@option{-codec} option. It makes @command{ffmpeg} omit the decoding and encoding
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step for the specified stream, so it does only demuxing and muxing. It is useful
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for changing the container format or modifying container-level metadata. The
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diagram above will, in this case, simplify to this:
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@example
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_______ ______________ ________
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| input | demuxer | encoded data | muxer | output |
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| file | ---------> | packets | -------> | file |
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|_______| |______________| |________|
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@end example
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Since there is no decoding or encoding, it is very fast and there is no quality
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loss. However, it might not work in some cases because of many factors. Applying
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filters is obviously also impossible, since filters work on uncompressed data.
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@c man end DETAILED DESCRIPTION
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@chapter Stream selection
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@c man begin STREAM SELECTION
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By default, @command{ffmpeg} includes only one stream of each type (video, audio, subtitle)
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present in the input files and adds them to each output file. It picks the
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"best" of each based upon the following criteria: for video, it is the stream
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with the highest resolution, for audio, it is the stream with the most channels, for
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subtitles, it is the first subtitle stream. In the case where several streams of
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the same type rate equally, the stream with the lowest index is chosen.
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You can disable some of those defaults by using the @code{-vn/-an/-sn} options. For
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full manual control, use the @code{-map} option, which disables the defaults just
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described.
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@c man end STREAM SELECTION
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@chapter Options
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@c man begin OPTIONS
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@include fftools-common-opts.texi
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@section Main options
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@table @option
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@item -f @var{fmt} (@emph{input/output})
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Force input or output file format. The format is normally auto detected for input
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files and guessed from the file extension for output files, so this option is not
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needed in most cases.
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@item -i @var{filename} (@emph{input})
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input file name
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@item -y (@emph{global})
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Overwrite output files without asking.
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@item -n (@emph{global})
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Do not overwrite output files, and exit immediately if a specified
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output file already exists.
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@item -c[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
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@itemx -codec[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
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Select an encoder (when used before an output file) or a decoder (when used
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before an input file) for one or more streams. @var{codec} is the name of a
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decoder/encoder or a special value @code{copy} (output only) to indicate that
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the stream is not to be re-encoded.
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For example
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@example
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ffmpeg -i INPUT -map 0 -c:v libx264 -c:a copy OUTPUT
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@end example
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encodes all video streams with libx264 and copies all audio streams.
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For each stream, the last matching @code{c} option is applied, so
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@example
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ffmpeg -i INPUT -map 0 -c copy -c:v:1 libx264 -c:a:137 libvorbis OUTPUT
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@end example
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will copy all the streams except the second video, which will be encoded with
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libx264, and the 138th audio, which will be encoded with libvorbis.
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@item -t @var{duration} (@emph{output})
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Stop writing the output after its duration reaches @var{duration}.
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@var{duration} may be a number in seconds, or in @code{hh:mm:ss[.xxx]} form.
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-to and -t are mutually exclusive and -t has priority.
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@item -to @var{position} (@emph{output})
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Stop writing the output at @var{position}.
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@var{position} may be a number in seconds, or in @code{hh:mm:ss[.xxx]} form.
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-to and -t are mutually exclusive and -t has priority.
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@item -fs @var{limit_size} (@emph{output})
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Set the file size limit, expressed in bytes.
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@item -ss @var{position} (@emph{input/output})
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When used as an input option (before @code{-i}), seeks in this input file to
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@var{position}. Note the in most formats it is not possible to seek exactly, so
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@command{ffmpeg} will seek to the closest seek point before @var{position}.
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When transcoding and @option{-accurate_seek} is enabled (the default), this
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extra segment between the seek point and @var{position} will be decoded and
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discarded. When doing stream copy or when @option{-noaccurate_seek} is used, it
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will be preserved.
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When used as an output option (before an output filename), decodes but discards
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input until the timestamps reach @var{position}.
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@var{position} may be either in seconds or in @code{hh:mm:ss[.xxx]} form.
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@item -itsoffset @var{offset} (@emph{input})
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Set the input time offset in seconds.
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@code{[-]hh:mm:ss[.xxx]} syntax is also supported.
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The offset is added to the timestamps of the input files.
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Specifying a positive offset means that the corresponding
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streams are delayed by @var{offset} seconds.
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@item -timestamp @var{time} (@emph{output})
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Set the recording timestamp in the container.
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The syntax for @var{time} is:
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@example
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now|([(YYYY-MM-DD|YYYYMMDD)[T|t| ]]((HH:MM:SS[.m...])|(HHMMSS[.m...]))[Z|z])
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@end example
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If the value is "now" it takes the current time.
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Time is local time unless 'Z' or 'z' is appended, in which case it is
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interpreted as UTC.
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If the year-month-day part is not specified it takes the current
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year-month-day.
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@item -metadata[:metadata_specifier] @var{key}=@var{value} (@emph{output,per-metadata})
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Set a metadata key/value pair.
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An optional @var{metadata_specifier} may be given to set metadata
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on streams or chapters. See @code{-map_metadata} documentation for
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details.
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This option overrides metadata set with @code{-map_metadata}. It is
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also possible to delete metadata by using an empty value.
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For example, for setting the title in the output file:
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@example
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ffmpeg -i in.avi -metadata title="my title" out.flv
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@end example
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To set the language of the first audio stream:
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@example
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ffmpeg -i INPUT -metadata:s:a:1 language=eng OUTPUT
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@end example
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@item -target @var{type} (@emph{output})
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Specify target file type (@code{vcd}, @code{svcd}, @code{dvd}, @code{dv},
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@code{dv50}). @var{type} may be prefixed with @code{pal-}, @code{ntsc-} or
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@code{film-} to use the corresponding standard. All the format options
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(bitrate, codecs, buffer sizes) are then set automatically. You can just type:
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@example
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ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
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@end example
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Nevertheless you can specify additional options as long as you know
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they do not conflict with the standard, as in:
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@example
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ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
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@end example
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@item -dframes @var{number} (@emph{output})
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Set the number of data frames to record. This is an alias for @code{-frames:d}.
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@item -frames[:@var{stream_specifier}] @var{framecount} (@emph{output,per-stream})
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Stop writing to the stream after @var{framecount} frames.
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@item -q[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
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@itemx -qscale[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
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Use fixed quality scale (VBR). The meaning of @var{q}/@var{qscale} is
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codec-dependent.
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If @var{qscale} is used without a @var{stream_specifier} then it applies only
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to the video stream, this is to maintain compatibility with previous behavior
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and as specifying the same codec specific value to 2 different codecs that is
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audio and video generally is not what is intended when no stream_specifier is
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used.
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@anchor{filter_option}
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@item -filter[:@var{stream_specifier}] @var{filtergraph} (@emph{output,per-stream})
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Create the filtergraph specified by @var{filtergraph} and use it to
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filter the stream.
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@var{filtergraph} is a description of the filtergraph to apply to
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the stream, and must have a single input and a single output of the
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same type of the stream. In the filtergraph, the input is associated
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to the label @code{in}, and the output to the label @code{out}. See
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the ffmpeg-filters manual for more information about the filtergraph
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syntax.
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See the @ref{filter_complex_option,,-filter_complex option} if you
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want to create filtergraphs with multiple inputs and/or outputs.
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@item -filter_script[:@var{stream_specifier}] @var{filename} (@emph{output,per-stream})
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This option is similar to @option{-filter}, the only difference is that its
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argument is the name of the file from which a filtergraph description is to be
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read.
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@item -pre[:@var{stream_specifier}] @var{preset_name} (@emph{output,per-stream})
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Specify the preset for matching stream(s).
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@item -stats (@emph{global})
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Print encoding progress/statistics. It is on by default, to explicitly
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disable it you need to specify @code{-nostats}.
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@item -progress @var{url} (@emph{global})
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Send program-friendly progress information to @var{url}.
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Progress information is written approximately every second and at the end of
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the encoding process. It is made of "@var{key}=@var{value}" lines. @var{key}
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consists of only alphanumeric characters. The last key of a sequence of
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progress information is always "progress".
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@item -stdin
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Enable interaction on standard input. On by default unless standard input is
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used as an input. To explicitly disable interaction you need to specify
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@code{-nostdin}.
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Disabling interaction on standard input is useful, for example, if
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ffmpeg is in the background process group. Roughly the same result can
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be achieved with @code{ffmpeg ... < /dev/null} but it requires a
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shell.
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@item -debug_ts (@emph{global})
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Print timestamp information. It is off by default. This option is
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mostly useful for testing and debugging purposes, and the output
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format may change from one version to another, so it should not be
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employed by portable scripts.
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See also the option @code{-fdebug ts}.
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@item -attach @var{filename} (@emph{output})
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Add an attachment to the output file. This is supported by a few formats
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like Matroska for e.g. fonts used in rendering subtitles. Attachments
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are implemented as a specific type of stream, so this option will add
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a new stream to the file. It is then possible to use per-stream options
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on this stream in the usual way. Attachment streams created with this
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option will be created after all the other streams (i.e. those created
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with @code{-map} or automatic mappings).
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Note that for Matroska you also have to set the mimetype metadata tag:
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@example
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ffmpeg -i INPUT -attach DejaVuSans.ttf -metadata:s:2 mimetype=application/x-truetype-font out.mkv
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@end example
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(assuming that the attachment stream will be third in the output file).
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@item -dump_attachment[:@var{stream_specifier}] @var{filename} (@emph{input,per-stream})
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Extract the matching attachment stream into a file named @var{filename}. If
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@var{filename} is empty, then the value of the @code{filename} metadata tag
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will be used.
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E.g. to extract the first attachment to a file named 'out.ttf':
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@example
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ffmpeg -dump_attachment:t:0 out.ttf -i INPUT
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@end example
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To extract all attachments to files determined by the @code{filename} tag:
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@example
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ffmpeg -dump_attachment:t "" -i INPUT
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@end example
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Technical note -- attachments are implemented as codec extradata, so this
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option can actually be used to extract extradata from any stream, not just
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attachments.
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@end table
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@section Video Options
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@table @option
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@item -vframes @var{number} (@emph{output})
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Set the number of video frames to record. This is an alias for @code{-frames:v}.
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@item -r[:@var{stream_specifier}] @var{fps} (@emph{input/output,per-stream})
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Set frame rate (Hz value, fraction or abbreviation).
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As an input option, ignore any timestamps stored in the file and instead
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generate timestamps assuming constant frame rate @var{fps}.
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As an output option, duplicate or drop input frames to achieve constant output
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frame rate @var{fps}.
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@item -s[:@var{stream_specifier}] @var{size} (@emph{input/output,per-stream})
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Set frame size.
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|
|
As an input option, this is a shortcut for the @option{video_size} private
|
|
option, recognized by some demuxers for which the frame size is either not
|
|
stored in the file or is configurable -- e.g. raw video or video grabbers.
|
|
|
|
As an output option, this inserts the @code{scale} video filter to the
|
|
@emph{end} of the corresponding filtergraph. Please use the @code{scale} filter
|
|
directly to insert it at the beginning or some other place.
|
|
|
|
The format is @samp{wxh} (default - same as source).
|
|
|
|
@item -aspect[:@var{stream_specifier}] @var{aspect} (@emph{output,per-stream})
|
|
Set the video display aspect ratio specified by @var{aspect}.
|
|
|
|
@var{aspect} can be a floating point number string, 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. For example "4:3",
|
|
"16:9", "1.3333", and "1.7777" are valid argument values.
|
|
|
|
If used together with @option{-vcodec copy}, it will affect the aspect ratio
|
|
stored at container level, but not the aspect ratio stored in encoded
|
|
frames, if it exists.
|
|
|
|
@item -vn (@emph{output})
|
|
Disable video recording.
|
|
|
|
@item -vcodec @var{codec} (@emph{output})
|
|
Set the video codec. This is an alias for @code{-codec:v}.
|
|
|
|
@item -pass[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
|
|
Select the pass number (1 or 2). It is used to do two-pass
|
|
video encoding. The statistics of the video are recorded in the first
|
|
pass into a log file (see also the option -passlogfile),
|
|
and in the second pass that log file is used to generate the video
|
|
at the exact requested bitrate.
|
|
On pass 1, you may just deactivate audio and set output to null,
|
|
examples for Windows and Unix:
|
|
@example
|
|
ffmpeg -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y NUL
|
|
ffmpeg -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null
|
|
@end example
|
|
|
|
@item -passlogfile[:@var{stream_specifier}] @var{prefix} (@emph{output,per-stream})
|
|
Set two-pass log file name prefix to @var{prefix}, the default file name
|
|
prefix is ``ffmpeg2pass''. The complete file name will be
|
|
@file{PREFIX-N.log}, where N is a number specific to the output
|
|
stream
|
|
|
|
@item -vlang @var{code}
|
|
Set the ISO 639 language code (3 letters) of the current video stream.
|
|
|
|
@item -vf @var{filtergraph} (@emph{output})
|
|
Create the filtergraph specified by @var{filtergraph} and use it to
|
|
filter the stream.
|
|
|
|
This is an alias for @code{-filter:v}, see the @ref{filter_option,,-filter option}.
|
|
@end table
|
|
|
|
@section Advanced Video Options
|
|
|
|
@table @option
|
|
@item -pix_fmt[:@var{stream_specifier}] @var{format} (@emph{input/output,per-stream})
|
|
Set pixel format. Use @code{-pix_fmts} to show all the supported
|
|
pixel formats.
|
|
If the selected pixel format can not be selected, ffmpeg will print a
|
|
warning and select the best pixel format supported by the encoder.
|
|
If @var{pix_fmt} is prefixed by a @code{+}, ffmpeg will exit with an error
|
|
if the requested pixel format can not be selected, and automatic conversions
|
|
inside filtergraphs are disabled.
|
|
If @var{pix_fmt} is a single @code{+}, ffmpeg selects the same pixel format
|
|
as the input (or graph output) and automatic conversions are disabled.
|
|
|
|
@item -sws_flags @var{flags} (@emph{input/output})
|
|
Set SwScaler flags.
|
|
@item -vdt @var{n}
|
|
Discard threshold.
|
|
|
|
@item -rc_override[:@var{stream_specifier}] @var{override} (@emph{output,per-stream})
|
|
Rate control override for specific intervals, formatted as "int,int,int"
|
|
list separated with slashes. Two first values are the beginning and
|
|
end frame numbers, last one is quantizer to use if positive, or quality
|
|
factor if negative.
|
|
|
|
@item -ilme
|
|
Force interlacing support in encoder (MPEG-2 and MPEG-4 only).
|
|
Use this option if your input file is interlaced and you want
|
|
to keep the interlaced format for minimum losses.
|
|
The alternative is to deinterlace the input stream with
|
|
@option{-deinterlace}, but deinterlacing introduces losses.
|
|
@item -psnr
|
|
Calculate PSNR of compressed frames.
|
|
@item -vstats
|
|
Dump video coding statistics to @file{vstats_HHMMSS.log}.
|
|
@item -vstats_file @var{file}
|
|
Dump video coding statistics to @var{file}.
|
|
@item -top[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
|
|
top=1/bottom=0/auto=-1 field first
|
|
@item -dc @var{precision}
|
|
Intra_dc_precision.
|
|
@item -vtag @var{fourcc/tag} (@emph{output})
|
|
Force video tag/fourcc. This is an alias for @code{-tag:v}.
|
|
@item -qphist (@emph{global})
|
|
Show QP histogram
|
|
@item -vbsf @var{bitstream_filter}
|
|
Deprecated see -bsf
|
|
|
|
@item -force_key_frames[:@var{stream_specifier}] @var{time}[,@var{time}...] (@emph{output,per-stream})
|
|
@item -force_key_frames[:@var{stream_specifier}] expr:@var{expr} (@emph{output,per-stream})
|
|
Force key frames at the specified timestamps, more precisely at the first
|
|
frames after each specified time.
|
|
|
|
If the argument is prefixed with @code{expr:}, the string @var{expr}
|
|
is interpreted like an expression and is evaluated for each frame. A
|
|
key frame is forced in case the evaluation is non-zero.
|
|
|
|
If one of the times is "@code{chapters}[@var{delta}]", it is expanded into
|
|
the time of the beginning of all chapters in the file, shifted by
|
|
@var{delta}, expressed as a time in seconds.
|
|
This option can be useful to ensure that a seek point is present at a
|
|
chapter mark or any other designated place in the output file.
|
|
|
|
For example, to insert a key frame at 5 minutes, plus key frames 0.1 second
|
|
before the beginning of every chapter:
|
|
@example
|
|
-force_key_frames 0:05:00,chapters-0.1
|
|
@end example
|
|
|
|
The expression in @var{expr} can contain the following constants:
|
|
@table @option
|
|
@item n
|
|
the number of current processed frame, starting from 0
|
|
@item n_forced
|
|
the number of forced frames
|
|
@item prev_forced_n
|
|
the number of the previous forced frame, it is @code{NAN} when no
|
|
keyframe was forced yet
|
|
@item prev_forced_t
|
|
the time of the previous forced frame, it is @code{NAN} when no
|
|
keyframe was forced yet
|
|
@item t
|
|
the time of the current processed frame
|
|
@end table
|
|
|
|
For example to force a key frame every 5 seconds, you can specify:
|
|
@example
|
|
-force_key_frames expr:gte(t,n_forced*5)
|
|
@end example
|
|
|
|
To force a key frame 5 seconds after the time of the last forced one,
|
|
starting from second 13:
|
|
@example
|
|
-force_key_frames expr:if(isnan(prev_forced_t),gte(t,13),gte(t,prev_forced_t+5))
|
|
@end example
|
|
|
|
Note that forcing too many keyframes is very harmful for the lookahead
|
|
algorithms of certain encoders: using fixed-GOP options or similar
|
|
would be more efficient.
|
|
|
|
@item -copyinkf[:@var{stream_specifier}] (@emph{output,per-stream})
|
|
When doing stream copy, copy also non-key frames found at the
|
|
beginning.
|
|
@end table
|
|
|
|
@section Audio Options
|
|
|
|
@table @option
|
|
@item -aframes @var{number} (@emph{output})
|
|
Set the number of audio frames to record. This is an alias for @code{-frames:a}.
|
|
@item -ar[:@var{stream_specifier}] @var{freq} (@emph{input/output,per-stream})
|
|
Set the audio sampling frequency. For output streams it is set by
|
|
default to the frequency of the corresponding input stream. For input
|
|
streams this option only makes sense for audio grabbing devices and raw
|
|
demuxers and is mapped to the corresponding demuxer options.
|
|
@item -aq @var{q} (@emph{output})
|
|
Set the audio quality (codec-specific, VBR). This is an alias for -q:a.
|
|
@item -ac[:@var{stream_specifier}] @var{channels} (@emph{input/output,per-stream})
|
|
Set the number of audio channels. For output streams it is set by
|
|
default to the number of input audio channels. For input streams
|
|
this option only makes sense for audio grabbing devices and raw demuxers
|
|
and is mapped to the corresponding demuxer options.
|
|
@item -an (@emph{output})
|
|
Disable audio recording.
|
|
@item -acodec @var{codec} (@emph{input/output})
|
|
Set the audio codec. This is an alias for @code{-codec:a}.
|
|
@item -sample_fmt[:@var{stream_specifier}] @var{sample_fmt} (@emph{output,per-stream})
|
|
Set the audio sample format. Use @code{-sample_fmts} to get a list
|
|
of supported sample formats.
|
|
|
|
@item -af @var{filtergraph} (@emph{output})
|
|
Create the filtergraph specified by @var{filtergraph} and use it to
|
|
filter the stream.
|
|
|
|
This is an alias for @code{-filter:a}, see the @ref{filter_option,,-filter option}.
|
|
@end table
|
|
|
|
@section Advanced Audio options:
|
|
|
|
@table @option
|
|
@item -atag @var{fourcc/tag} (@emph{output})
|
|
Force audio tag/fourcc. This is an alias for @code{-tag:a}.
|
|
@item -absf @var{bitstream_filter}
|
|
Deprecated, see -bsf
|
|
@item -guess_layout_max @var{channels} (@emph{input,per-stream})
|
|
If some input channel layout is not known, try to guess only if it
|
|
corresponds to at most the specified number of channels. For example, 2
|
|
tells to @command{ffmpeg} to recognize 1 channel as mono and 2 channels as
|
|
stereo but not 6 channels as 5.1. The default is to always try to guess. Use
|
|
0 to disable all guessing.
|
|
@end table
|
|
|
|
@section Subtitle options:
|
|
|
|
@table @option
|
|
@item -slang @var{code}
|
|
Set the ISO 639 language code (3 letters) of the current subtitle stream.
|
|
@item -scodec @var{codec} (@emph{input/output})
|
|
Set the subtitle codec. This is an alias for @code{-codec:s}.
|
|
@item -sn (@emph{output})
|
|
Disable subtitle recording.
|
|
@item -sbsf @var{bitstream_filter}
|
|
Deprecated, see -bsf
|
|
@end table
|
|
|
|
@section Advanced Subtitle options:
|
|
|
|
@table @option
|
|
|
|
@item -fix_sub_duration
|
|
Fix subtitles durations. For each subtitle, wait for the next packet in the
|
|
same stream and adjust the duration of the first to avoid overlap. This is
|
|
necessary with some subtitles codecs, especially DVB subtitles, because the
|
|
duration in the original packet is only a rough estimate and the end is
|
|
actually marked by an empty subtitle frame. Failing to use this option when
|
|
necessary can result in exaggerated durations or muxing failures due to
|
|
non-monotonic timestamps.
|
|
|
|
Note that this option will delay the output of all data until the next
|
|
subtitle packet is decoded: it may increase memory consumption and latency a
|
|
lot.
|
|
|
|
@item -canvas_size @var{size}
|
|
Set the size of the canvas used to render subtitles.
|
|
|
|
@end table
|
|
|
|
@section Advanced options
|
|
|
|
@table @option
|
|
@item -map [-]@var{input_file_id}[:@var{stream_specifier}][,@var{sync_file_id}[:@var{stream_specifier}]] | @var{[linklabel]} (@emph{output})
|
|
|
|
Designate one or more input streams as a source for the output file. Each input
|
|
stream is identified by the input file index @var{input_file_id} and
|
|
the input stream index @var{input_stream_id} within the input
|
|
file. Both indices start at 0. If specified,
|
|
@var{sync_file_id}:@var{stream_specifier} sets which input stream
|
|
is used as a presentation sync reference.
|
|
|
|
The first @code{-map} option on the command line specifies the
|
|
source for output stream 0, the second @code{-map} option specifies
|
|
the source for output stream 1, etc.
|
|
|
|
A @code{-} character before the stream identifier creates a "negative" mapping.
|
|
It disables matching streams from already created mappings.
|
|
|
|
An alternative @var{[linklabel]} form will map outputs from complex filter
|
|
graphs (see the @option{-filter_complex} option) to the output file.
|
|
@var{linklabel} must correspond to a defined output link label in the graph.
|
|
|
|
For example, to map ALL streams from the first input file to output
|
|
@example
|
|
ffmpeg -i INPUT -map 0 output
|
|
@end example
|
|
|
|
For example, if you have two audio streams in the first input file,
|
|
these streams are identified by "0:0" and "0:1". You can use
|
|
@code{-map} to select which streams to place in an output file. For
|
|
example:
|
|
@example
|
|
ffmpeg -i INPUT -map 0:1 out.wav
|
|
@end example
|
|
will map the input stream in @file{INPUT} identified by "0:1" to
|
|
the (single) output stream in @file{out.wav}.
|
|
|
|
For example, to select the stream with index 2 from input file
|
|
@file{a.mov} (specified by the identifier "0:2"), and stream with
|
|
index 6 from input @file{b.mov} (specified by the identifier "1:6"),
|
|
and copy them to the output file @file{out.mov}:
|
|
@example
|
|
ffmpeg -i a.mov -i b.mov -c copy -map 0:2 -map 1:6 out.mov
|
|
@end example
|
|
|
|
To select all video and the third audio stream from an input file:
|
|
@example
|
|
ffmpeg -i INPUT -map 0:v -map 0:a:2 OUTPUT
|
|
@end example
|
|
|
|
To map all the streams except the second audio, use negative mappings
|
|
@example
|
|
ffmpeg -i INPUT -map 0 -map -0:a:1 OUTPUT
|
|
@end example
|
|
|
|
Note that using this option disables the default mappings for this output file.
|
|
|
|
@item -map_channel [@var{input_file_id}.@var{stream_specifier}.@var{channel_id}|-1][:@var{output_file_id}.@var{stream_specifier}]
|
|
Map an audio channel from a given input to an output. If
|
|
@var{output_file_id}.@var{stream_specifier} is not set, the audio channel will
|
|
be mapped on all the audio streams.
|
|
|
|
Using "-1" instead of
|
|
@var{input_file_id}.@var{stream_specifier}.@var{channel_id} will map a muted
|
|
channel.
|
|
|
|
For example, assuming @var{INPUT} is a stereo audio file, you can switch the
|
|
two audio channels with the following command:
|
|
@example
|
|
ffmpeg -i INPUT -map_channel 0.0.1 -map_channel 0.0.0 OUTPUT
|
|
@end example
|
|
|
|
If you want to mute the first channel and keep the second:
|
|
@example
|
|
ffmpeg -i INPUT -map_channel -1 -map_channel 0.0.1 OUTPUT
|
|
@end example
|
|
|
|
The order of the "-map_channel" option specifies the order of the channels in
|
|
the output stream. The output channel layout is guessed from the number of
|
|
channels mapped (mono if one "-map_channel", stereo if two, etc.). Using "-ac"
|
|
in combination of "-map_channel" makes the channel gain levels to be updated if
|
|
input and output channel layouts don't match (for instance two "-map_channel"
|
|
options and "-ac 6").
|
|
|
|
You can also extract each channel of an input to specific outputs; the following
|
|
command extracts two channels of the @var{INPUT} audio stream (file 0, stream 0)
|
|
to the respective @var{OUTPUT_CH0} and @var{OUTPUT_CH1} outputs:
|
|
@example
|
|
ffmpeg -i INPUT -map_channel 0.0.0 OUTPUT_CH0 -map_channel 0.0.1 OUTPUT_CH1
|
|
@end example
|
|
|
|
The following example splits the channels of a stereo input into two separate
|
|
streams, which are put into the same output file:
|
|
@example
|
|
ffmpeg -i stereo.wav -map 0:0 -map 0:0 -map_channel 0.0.0:0.0 -map_channel 0.0.1:0.1 -y out.ogg
|
|
@end example
|
|
|
|
Note that currently each output stream can only contain channels from a single
|
|
input stream; you can't for example use "-map_channel" to pick multiple input
|
|
audio channels contained in different streams (from the same or different files)
|
|
and merge them into a single output stream. It is therefore not currently
|
|
possible, for example, to turn two separate mono streams into a single stereo
|
|
stream. However splitting a stereo stream into two single channel mono streams
|
|
is possible.
|
|
|
|
If you need this feature, a possible workaround is to use the @emph{amerge}
|
|
filter. For example, if you need to merge a media (here @file{input.mkv}) with 2
|
|
mono audio streams into one single stereo channel audio stream (and keep the
|
|
video stream), you can use the following command:
|
|
@example
|
|
ffmpeg -i input.mkv -filter_complex "[0:1] [0:2] amerge" -c:a pcm_s16le -c:v copy output.mkv
|
|
@end example
|
|
|
|
@item -map_metadata[:@var{metadata_spec_out}] @var{infile}[:@var{metadata_spec_in}] (@emph{output,per-metadata})
|
|
Set metadata information of the next output file from @var{infile}. Note that
|
|
those are file indices (zero-based), not filenames.
|
|
Optional @var{metadata_spec_in/out} parameters specify, which metadata to copy.
|
|
A metadata specifier can have the following forms:
|
|
@table @option
|
|
@item @var{g}
|
|
global metadata, i.e. metadata that applies to the whole file
|
|
|
|
@item @var{s}[:@var{stream_spec}]
|
|
per-stream metadata. @var{stream_spec} is a stream specifier as described
|
|
in the @ref{Stream specifiers} chapter. In an input metadata specifier, the first
|
|
matching stream is copied from. In an output metadata specifier, all matching
|
|
streams are copied to.
|
|
|
|
@item @var{c}:@var{chapter_index}
|
|
per-chapter metadata. @var{chapter_index} is the zero-based chapter index.
|
|
|
|
@item @var{p}:@var{program_index}
|
|
per-program metadata. @var{program_index} is the zero-based program index.
|
|
@end table
|
|
If metadata specifier is omitted, it defaults to global.
|
|
|
|
By default, global metadata is copied from the first input file,
|
|
per-stream and per-chapter metadata is copied along with streams/chapters. These
|
|
default mappings are disabled by creating any mapping of the relevant type. A negative
|
|
file index can be used to create a dummy mapping that just disables automatic copying.
|
|
|
|
For example to copy metadata from the first stream of the input file to global metadata
|
|
of the output file:
|
|
@example
|
|
ffmpeg -i in.ogg -map_metadata 0:s:0 out.mp3
|
|
@end example
|
|
|
|
To do the reverse, i.e. copy global metadata to all audio streams:
|
|
@example
|
|
ffmpeg -i in.mkv -map_metadata:s:a 0:g out.mkv
|
|
@end example
|
|
Note that simple @code{0} would work as well in this example, since global
|
|
metadata is assumed by default.
|
|
|
|
@item -map_chapters @var{input_file_index} (@emph{output})
|
|
Copy chapters from input file with index @var{input_file_index} to the next
|
|
output file. If no chapter mapping is specified, then chapters are copied from
|
|
the first input file with at least one chapter. Use a negative file index to
|
|
disable any chapter copying.
|
|
|
|
@item -benchmark (@emph{global})
|
|
Show benchmarking information at the end of an encode.
|
|
Shows CPU time used and maximum memory consumption.
|
|
Maximum memory consumption is not supported on all systems,
|
|
it will usually display as 0 if not supported.
|
|
@item -benchmark_all (@emph{global})
|
|
Show benchmarking information during the encode.
|
|
Shows CPU time used in various steps (audio/video encode/decode).
|
|
@item -timelimit @var{duration} (@emph{global})
|
|
Exit after ffmpeg has been running for @var{duration} seconds.
|
|
@item -dump (@emph{global})
|
|
Dump each input packet to stderr.
|
|
@item -hex (@emph{global})
|
|
When dumping packets, also dump the payload.
|
|
@item -re (@emph{input})
|
|
Read input at native frame rate. Mainly used to simulate a grab device.
|
|
or live input stream (e.g. when reading from a file). Should not be used
|
|
with actual grab devices or live input streams (where it can cause packet
|
|
loss).
|
|
By default @command{ffmpeg} attempts to read the input(s) as fast as possible.
|
|
This option will slow down the reading of the input(s) to the native frame rate
|
|
of the input(s). It is useful for real-time output (e.g. live streaming).
|
|
@item -loop_input
|
|
Loop over the input stream. Currently it works only for image
|
|
streams. This option is used for automatic FFserver testing.
|
|
This option is deprecated, use -loop 1.
|
|
@item -loop_output @var{number_of_times}
|
|
Repeatedly loop output for formats that support looping such as animated GIF
|
|
(0 will loop the output infinitely).
|
|
This option is deprecated, use -loop.
|
|
@item -vsync @var{parameter}
|
|
Video sync method.
|
|
For compatibility reasons old values can be specified as numbers.
|
|
Newly added values will have to be specified as strings always.
|
|
|
|
@table @option
|
|
@item 0, passthrough
|
|
Each frame is passed with its timestamp from the demuxer to the muxer.
|
|
@item 1, cfr
|
|
Frames will be duplicated and dropped to achieve exactly the requested
|
|
constant frame rate.
|
|
@item 2, vfr
|
|
Frames are passed through with their timestamp or dropped so as to
|
|
prevent 2 frames from having the same timestamp.
|
|
@item drop
|
|
As passthrough but destroys all timestamps, making the muxer generate
|
|
fresh timestamps based on frame-rate.
|
|
@item -1, auto
|
|
Chooses between 1 and 2 depending on muxer capabilities. This is the
|
|
default method.
|
|
@end table
|
|
|
|
Note that the timestamps may be further modified by the muxer, after this.
|
|
For example, in the case that the format option @option{avoid_negative_ts}
|
|
is enabled.
|
|
|
|
With -map you can select from which stream the timestamps should be
|
|
taken. You can leave either video or audio unchanged and sync the
|
|
remaining stream(s) to the unchanged one.
|
|
|
|
@item -async @var{samples_per_second}
|
|
Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
|
|
the parameter is the maximum samples per second by which the audio is changed.
|
|
-async 1 is a special case where only the start of the audio stream is corrected
|
|
without any later correction.
|
|
|
|
Note that the timestamps may be further modified by the muxer, after this.
|
|
For example, in the case that the format option @option{avoid_negative_ts}
|
|
is enabled.
|
|
|
|
This option has been deprecated. Use the @code{aresample} audio filter instead.
|
|
|
|
@item -copyts
|
|
Do not process input timestamps, but keep their values without trying
|
|
to sanitize them. In particular, do not remove the initial start time
|
|
offset value.
|
|
|
|
Note that, depending on the @option{vsync} option or on specific muxer
|
|
processing (e.g. in case the format option @option{avoid_negative_ts}
|
|
is enabled) the output timestamps may mismatch with the input
|
|
timestamps even when this option is selected.
|
|
|
|
@item -copytb @var{mode}
|
|
Specify how to set the encoder timebase when stream copying. @var{mode} is an
|
|
integer numeric value, and can assume one of the following values:
|
|
|
|
@table @option
|
|
@item 1
|
|
Use the demuxer timebase.
|
|
|
|
The time base is copied to the output encoder from the corresponding input
|
|
demuxer. This is sometimes required to avoid non monotonically increasing
|
|
timestamps when copying video streams with variable frame rate.
|
|
|
|
@item 0
|
|
Use the decoder timebase.
|
|
|
|
The time base is copied to the output encoder from the corresponding input
|
|
decoder.
|
|
|
|
@item -1
|
|
Try to make the choice automatically, in order to generate a sane output.
|
|
@end table
|
|
|
|
Default value is -1.
|
|
|
|
@item -shortest (@emph{output})
|
|
Finish encoding when the shortest input stream ends.
|
|
@item -dts_delta_threshold
|
|
Timestamp discontinuity delta threshold.
|
|
@item -muxdelay @var{seconds} (@emph{input})
|
|
Set the maximum demux-decode delay.
|
|
@item -muxpreload @var{seconds} (@emph{input})
|
|
Set the initial demux-decode delay.
|
|
@item -streamid @var{output-stream-index}:@var{new-value} (@emph{output})
|
|
Assign a new stream-id value to an output stream. This option should be
|
|
specified prior to the output filename to which it applies.
|
|
For the situation where multiple output files exist, a streamid
|
|
may be reassigned to a different value.
|
|
|
|
For example, to set the stream 0 PID to 33 and the stream 1 PID to 36 for
|
|
an output mpegts file:
|
|
@example
|
|
ffmpeg -i infile -streamid 0:33 -streamid 1:36 out.ts
|
|
@end example
|
|
|
|
@item -bsf[:@var{stream_specifier}] @var{bitstream_filters} (@emph{output,per-stream})
|
|
Set bitstream filters for matching streams. @var{bitstream_filters} is
|
|
a comma-separated list of bitstream filters. Use the @code{-bsfs} option
|
|
to get the list of bitstream filters.
|
|
@example
|
|
ffmpeg -i h264.mp4 -c:v copy -bsf:v h264_mp4toannexb -an out.h264
|
|
@end example
|
|
@example
|
|
ffmpeg -i file.mov -an -vn -bsf:s mov2textsub -c:s copy -f rawvideo sub.txt
|
|
@end example
|
|
|
|
@item -tag[:@var{stream_specifier}] @var{codec_tag} (@emph{per-stream})
|
|
Force a tag/fourcc for matching streams.
|
|
|
|
@item -timecode @var{hh}:@var{mm}:@var{ss}SEP@var{ff}
|
|
Specify Timecode for writing. @var{SEP} is ':' for non drop timecode and ';'
|
|
(or '.') for drop.
|
|
@example
|
|
ffmpeg -i input.mpg -timecode 01:02:03.04 -r 30000/1001 -s ntsc output.mpg
|
|
@end example
|
|
|
|
@anchor{filter_complex_option}
|
|
@item -filter_complex @var{filtergraph} (@emph{global})
|
|
Define a complex filtergraph, i.e. one with arbitrary number of inputs and/or
|
|
outputs. For simple graphs -- those with one input and one output of the same
|
|
type -- see the @option{-filter} options. @var{filtergraph} is a description of
|
|
the filtergraph, as described in the ``Filtergraph syntax'' section of the
|
|
ffmpeg-filters manual.
|
|
|
|
Input link labels must refer to input streams using the
|
|
@code{[file_index:stream_specifier]} syntax (i.e. the same as @option{-map}
|
|
uses). If @var{stream_specifier} matches multiple streams, the first one will be
|
|
used. An unlabeled input will be connected to the first unused input stream of
|
|
the matching type.
|
|
|
|
Output link labels are referred to with @option{-map}. Unlabeled outputs are
|
|
added to the first output file.
|
|
|
|
Note that with this option it is possible to use only lavfi sources without
|
|
normal input files.
|
|
|
|
For example, to overlay an image over video
|
|
@example
|
|
ffmpeg -i video.mkv -i image.png -filter_complex '[0:v][1:v]overlay[out]' -map
|
|
'[out]' out.mkv
|
|
@end example
|
|
Here @code{[0:v]} refers to the first video stream in the first input file,
|
|
which is linked to the first (main) input of the overlay filter. Similarly the
|
|
first video stream in the second input is linked to the second (overlay) input
|
|
of overlay.
|
|
|
|
Assuming there is only one video stream in each input file, we can omit input
|
|
labels, so the above is equivalent to
|
|
@example
|
|
ffmpeg -i video.mkv -i image.png -filter_complex 'overlay[out]' -map
|
|
'[out]' out.mkv
|
|
@end example
|
|
|
|
Furthermore we can omit the output label and the single output from the filter
|
|
graph will be added to the output file automatically, so we can simply write
|
|
@example
|
|
ffmpeg -i video.mkv -i image.png -filter_complex 'overlay' out.mkv
|
|
@end example
|
|
|
|
To generate 5 seconds of pure red video using lavfi @code{color} source:
|
|
@example
|
|
ffmpeg -filter_complex 'color=c=red' -t 5 out.mkv
|
|
@end example
|
|
|
|
@item -lavfi @var{filtergraph} (@emph{global})
|
|
Define a complex filtergraph, i.e. one with arbitrary number of inputs and/or
|
|
outputs. Equivalent to @option{-filter_complex}.
|
|
|
|
@item -filter_complex_script @var{filename} (@emph{global})
|
|
This option is similar to @option{-filter_complex}, the only difference is that
|
|
its argument is the name of the file from which a complex filtergraph
|
|
description is to be read.
|
|
|
|
@item -accurate_seek (@emph{input})
|
|
This option enables or disables accurate seeking in input files with the
|
|
@option{-ss} option. It is enabled by default, so seeking is accurate when
|
|
transcoding. Use @option{-noaccurate_seek} to disable it, which may be useful
|
|
e.g. when copying some streams and transcoding the others.
|
|
|
|
@item -override_ffserver (@emph{global})
|
|
Overrides the input specifications from ffserver. Using this option you can
|
|
map any input stream to ffserver and control many aspects of the encoding from
|
|
ffmpeg. Without this option ffmpeg will transmit to ffserver what is requested by
|
|
ffserver.
|
|
The option is intended for cases where features are needed that cannot be
|
|
specified to ffserver but can be to ffmpeg.
|
|
|
|
@end table
|
|
|
|
As a special exception, you can use a bitmap subtitle stream as input: it
|
|
will be converted into a video with the same size as the largest video in
|
|
the file, or 720x576 if no video is present. Note that this is an
|
|
experimental and temporary solution. It will be removed once libavfilter has
|
|
proper support for subtitles.
|
|
|
|
For example, to hardcode subtitles on top of a DVB-T recording stored in
|
|
MPEG-TS format, delaying the subtitles by 1 second:
|
|
@example
|
|
ffmpeg -i input.ts -filter_complex \
|
|
'[#0x2ef] setpts=PTS+1/TB [sub] ; [#0x2d0] [sub] overlay' \
|
|
-sn -map '#0x2dc' output.mkv
|
|
@end example
|
|
(0x2d0, 0x2dc and 0x2ef are the MPEG-TS PIDs of respectively the video,
|
|
audio and subtitles streams; 0:0, 0:3 and 0:7 would have worked too)
|
|
|
|
@section Preset files
|
|
A preset file contains a sequence of @var{option}=@var{value} pairs,
|
|
one for each line, specifying a sequence of options which would be
|
|
awkward to specify on the command line. Lines starting with the hash
|
|
('#') character are ignored and are used to provide comments. Check
|
|
the @file{presets} directory in the FFmpeg source tree for examples.
|
|
|
|
Preset files are specified with the @code{vpre}, @code{apre},
|
|
@code{spre}, and @code{fpre} options. The @code{fpre} option takes the
|
|
filename of the preset instead of a preset name as input and can be
|
|
used for any kind of codec. For the @code{vpre}, @code{apre}, and
|
|
@code{spre} options, the options specified in a preset file are
|
|
applied to the currently selected codec of the same type as the preset
|
|
option.
|
|
|
|
The argument passed to the @code{vpre}, @code{apre}, and @code{spre}
|
|
preset options identifies the preset file to use according to the
|
|
following rules:
|
|
|
|
First ffmpeg searches for a file named @var{arg}.ffpreset in the
|
|
directories @file{$FFMPEG_DATADIR} (if set), and @file{$HOME/.ffmpeg}, and in
|
|
the datadir defined at configuration time (usually @file{PREFIX/share/ffmpeg})
|
|
or in a @file{ffpresets} folder along the executable on win32,
|
|
in that order. For example, if the argument is @code{libvpx-1080p}, it will
|
|
search for the file @file{libvpx-1080p.ffpreset}.
|
|
|
|
If no such file is found, then ffmpeg will search for a file named
|
|
@var{codec_name}-@var{arg}.ffpreset in the above-mentioned
|
|
directories, where @var{codec_name} is the name of the codec to which
|
|
the preset file options will be applied. For example, if you select
|
|
the video codec with @code{-vcodec libvpx} and use @code{-vpre 1080p},
|
|
then it will search for the file @file{libvpx-1080p.ffpreset}.
|
|
@c man end OPTIONS
|
|
|
|
@chapter Tips
|
|
@c man begin TIPS
|
|
|
|
@itemize
|
|
@item
|
|
For streaming at very low bitrates, use a low frame rate
|
|
and a small GOP size. This is especially true for RealVideo where
|
|
the Linux player does not seem to be very fast, so it can miss
|
|
frames. An example is:
|
|
|
|
@example
|
|
ffmpeg -g 3 -r 3 -t 10 -b:v 50k -s qcif -f rv10 /tmp/b.rm
|
|
@end example
|
|
|
|
@item
|
|
The parameter 'q' which is displayed while encoding is the current
|
|
quantizer. The value 1 indicates that a very good quality could
|
|
be achieved. The value 31 indicates the worst quality. If q=31 appears
|
|
too often, it means that the encoder cannot compress enough to meet
|
|
your bitrate. You must either increase the bitrate, decrease the
|
|
frame rate or decrease the frame size.
|
|
|
|
@item
|
|
If your computer is not fast enough, you can speed up the
|
|
compression at the expense of the compression ratio. You can use
|
|
'-me zero' to speed up motion estimation, and '-g 0' to disable
|
|
motion estimation completely (you have only I-frames, which means it
|
|
is about as good as JPEG compression).
|
|
|
|
@item
|
|
To have very low audio bitrates, reduce the sampling frequency
|
|
(down to 22050 Hz for MPEG audio, 22050 or 11025 for AC-3).
|
|
|
|
@item
|
|
To have a constant quality (but a variable bitrate), use the option
|
|
'-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
|
|
quality).
|
|
|
|
@end itemize
|
|
@c man end TIPS
|
|
|
|
@chapter Examples
|
|
@c man begin EXAMPLES
|
|
|
|
@section Preset files
|
|
|
|
A preset file contains a sequence of @var{option=value} pairs, one for
|
|
each line, specifying a sequence of options which can be specified also on
|
|
the command line. Lines starting with the hash ('#') character are ignored and
|
|
are used to provide comments. Empty lines are also ignored. Check the
|
|
@file{presets} directory in the FFmpeg source tree for examples.
|
|
|
|
Preset files are specified with the @code{pre} option, this option takes a
|
|
preset name as input. FFmpeg searches for a file named @var{preset_name}.avpreset in
|
|
the directories @file{$AVCONV_DATADIR} (if set), and @file{$HOME/.ffmpeg}, and in
|
|
the data directory defined at configuration time (usually @file{$PREFIX/share/ffmpeg})
|
|
in that order. For example, if the argument is @code{libx264-max}, it will
|
|
search for the file @file{libx264-max.avpreset}.
|
|
|
|
@section Video and Audio grabbing
|
|
|
|
If you specify the input format and device then ffmpeg can grab video
|
|
and audio directly.
|
|
|
|
@example
|
|
ffmpeg -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
|
|
@end example
|
|
|
|
Or with an ALSA audio source (mono input, card id 1) instead of OSS:
|
|
@example
|
|
ffmpeg -f alsa -ac 1 -i hw:1 -f video4linux2 -i /dev/video0 /tmp/out.mpg
|
|
@end example
|
|
|
|
Note that you must activate the right video source and channel before
|
|
launching ffmpeg with any TV viewer such as
|
|
@uref{http://linux.bytesex.org/xawtv/, xawtv} by Gerd Knorr. You also
|
|
have to set the audio recording levels correctly with a
|
|
standard mixer.
|
|
|
|
@section X11 grabbing
|
|
|
|
Grab the X11 display with ffmpeg via
|
|
|
|
@example
|
|
ffmpeg -f x11grab -video_size cif -framerate 25 -i :0.0 /tmp/out.mpg
|
|
@end example
|
|
|
|
0.0 is display.screen number of your X11 server, same as
|
|
the DISPLAY environment variable.
|
|
|
|
@example
|
|
ffmpeg -f x11grab -video_size cif -framerate 25 -i :0.0+10,20 /tmp/out.mpg
|
|
@end example
|
|
|
|
0.0 is display.screen number of your X11 server, same as the DISPLAY environment
|
|
variable. 10 is the x-offset and 20 the y-offset for the grabbing.
|
|
|
|
@section Video and Audio file format conversion
|
|
|
|
Any supported file format and protocol can serve as input to ffmpeg:
|
|
|
|
Examples:
|
|
@itemize
|
|
@item
|
|
You can use YUV files as input:
|
|
|
|
@example
|
|
ffmpeg -i /tmp/test%d.Y /tmp/out.mpg
|
|
@end example
|
|
|
|
It will use the files:
|
|
@example
|
|
/tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
|
|
/tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
|
|
@end example
|
|
|
|
The Y files use twice the resolution of the U and V files. They are
|
|
raw files, without header. They can be generated by all decent video
|
|
decoders. You must specify the size of the image with the @option{-s} option
|
|
if ffmpeg cannot guess it.
|
|
|
|
@item
|
|
You can input from a raw YUV420P file:
|
|
|
|
@example
|
|
ffmpeg -i /tmp/test.yuv /tmp/out.avi
|
|
@end example
|
|
|
|
test.yuv is a file containing raw YUV planar data. Each frame is composed
|
|
of the Y plane followed by the U and V planes at half vertical and
|
|
horizontal resolution.
|
|
|
|
@item
|
|
You can output to a raw YUV420P file:
|
|
|
|
@example
|
|
ffmpeg -i mydivx.avi hugefile.yuv
|
|
@end example
|
|
|
|
@item
|
|
You can set several input files and output files:
|
|
|
|
@example
|
|
ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
|
|
@end example
|
|
|
|
Converts the audio file a.wav and the raw YUV video file a.yuv
|
|
to MPEG file a.mpg.
|
|
|
|
@item
|
|
You can also do audio and video conversions at the same time:
|
|
|
|
@example
|
|
ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2
|
|
@end example
|
|
|
|
Converts a.wav to MPEG audio at 22050 Hz sample rate.
|
|
|
|
@item
|
|
You can encode to several formats at the same time and define a
|
|
mapping from input stream to output streams:
|
|
|
|
@example
|
|
ffmpeg -i /tmp/a.wav -map 0:a -b:a 64k /tmp/a.mp2 -map 0:a -b:a 128k /tmp/b.mp2
|
|
@end example
|
|
|
|
Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
|
|
file:index' specifies which input stream is used for each output
|
|
stream, in the order of the definition of output streams.
|
|
|
|
@item
|
|
You can transcode decrypted VOBs:
|
|
|
|
@example
|
|
ffmpeg -i snatch_1.vob -f avi -c:v mpeg4 -b:v 800k -g 300 -bf 2 -c:a libmp3lame -b:a 128k snatch.avi
|
|
@end example
|
|
|
|
This is a typical DVD ripping example; the input is a VOB file, the
|
|
output an AVI file with MPEG-4 video and MP3 audio. Note that in this
|
|
command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
|
|
GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
|
|
input video. Furthermore, the audio stream is MP3-encoded so you need
|
|
to enable LAME support by passing @code{--enable-libmp3lame} to configure.
|
|
The mapping is particularly useful for DVD transcoding
|
|
to get the desired audio language.
|
|
|
|
NOTE: To see the supported input formats, use @code{ffmpeg -formats}.
|
|
|
|
@item
|
|
You can extract images from a video, or create a video from many images:
|
|
|
|
For extracting images from a video:
|
|
@example
|
|
ffmpeg -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg
|
|
@end example
|
|
|
|
This will extract one video frame per second from the video and will
|
|
output them in files named @file{foo-001.jpeg}, @file{foo-002.jpeg},
|
|
etc. Images will be rescaled to fit the new WxH values.
|
|
|
|
If you want to extract just a limited number of frames, you can use the
|
|
above command in combination with the -vframes or -t option, or in
|
|
combination with -ss to start extracting from a certain point in time.
|
|
|
|
For creating a video from many images:
|
|
@example
|
|
ffmpeg -f image2 -i foo-%03d.jpeg -r 12 -s WxH foo.avi
|
|
@end example
|
|
|
|
The syntax @code{foo-%03d.jpeg} specifies to use a decimal number
|
|
composed of three digits padded with zeroes to express the sequence
|
|
number. It is the same syntax supported by the C printf function, but
|
|
only formats accepting a normal integer are suitable.
|
|
|
|
When importing an image sequence, -i also supports expanding
|
|
shell-like wildcard patterns (globbing) internally, by selecting the
|
|
image2-specific @code{-pattern_type glob} option.
|
|
|
|
For example, for creating a video from filenames matching the glob pattern
|
|
@code{foo-*.jpeg}:
|
|
@example
|
|
ffmpeg -f image2 -pattern_type glob -i 'foo-*.jpeg' -r 12 -s WxH foo.avi
|
|
@end example
|
|
|
|
@item
|
|
You can put many streams of the same type in the output:
|
|
|
|
@example
|
|
ffmpeg -i test1.avi -i test2.avi -map 0:3 -map 0:2 -map 0:1 -map 0:0 -c copy test12.nut
|
|
@end example
|
|
|
|
The resulting output file @file{test12.avi} will contain first four streams from
|
|
the input file in reverse order.
|
|
|
|
@item
|
|
To force CBR video output:
|
|
@example
|
|
ffmpeg -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v
|
|
@end example
|
|
|
|
@item
|
|
The four options lmin, lmax, mblmin and mblmax use 'lambda' units,
|
|
but you may use the QP2LAMBDA constant to easily convert from 'q' units:
|
|
@example
|
|
ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext
|
|
@end example
|
|
|
|
@end itemize
|
|
@c man end EXAMPLES
|
|
|
|
@include config.texi
|
|
@ifset config-all
|
|
@ifset config-avutil
|
|
@include utils.texi
|
|
@end ifset
|
|
@ifset config-avcodec
|
|
@include codecs.texi
|
|
@include bitstream_filters.texi
|
|
@end ifset
|
|
@ifset config-avformat
|
|
@include formats.texi
|
|
@include protocols.texi
|
|
@end ifset
|
|
@ifset config-avdevice
|
|
@include devices.texi
|
|
@end ifset
|
|
@ifset config-swresample
|
|
@include resampler.texi
|
|
@end ifset
|
|
@ifset config-swscale
|
|
@include scaler.texi
|
|
@end ifset
|
|
@ifset config-avfilter
|
|
@include filters.texi
|
|
@end ifset
|
|
@end ifset
|
|
|
|
@chapter See Also
|
|
|
|
@ifhtml
|
|
@ifset config-all
|
|
@url{ffmpeg.html,ffmpeg}
|
|
@end ifset
|
|
@ifset config-not-all
|
|
@url{ffmpeg-all.html,ffmpeg-all},
|
|
@end ifset
|
|
@url{ffplay.html,ffplay}, @url{ffprobe.html,ffprobe}, @url{ffserver.html,ffserver},
|
|
@url{ffmpeg-utils.html,ffmpeg-utils},
|
|
@url{ffmpeg-scaler.html,ffmpeg-scaler},
|
|
@url{ffmpeg-resampler.html,ffmpeg-resampler},
|
|
@url{ffmpeg-codecs.html,ffmpeg-codecs},
|
|
@url{ffmpeg-bitstream-filters.html,ffmpeg-bitstream-filters},
|
|
@url{ffmpeg-formats.html,ffmpeg-formats},
|
|
@url{ffmpeg-devices.html,ffmpeg-devices},
|
|
@url{ffmpeg-protocols.html,ffmpeg-protocols},
|
|
@url{ffmpeg-filters.html,ffmpeg-filters}
|
|
@end ifhtml
|
|
|
|
@ifnothtml
|
|
@ifset config-all
|
|
ffmpeg(1),
|
|
@end ifset
|
|
@ifset config-not-all
|
|
ffmpeg-all(1),
|
|
@end ifset
|
|
ffplay(1), ffprobe(1), ffserver(1),
|
|
ffmpeg-utils(1), ffmpeg-scaler(1), ffmpeg-resampler(1),
|
|
ffmpeg-codecs(1), ffmpeg-bitstream-filters(1), ffmpeg-formats(1),
|
|
ffmpeg-devices(1), ffmpeg-protocols(1), ffmpeg-filters(1)
|
|
@end ifnothtml
|
|
|
|
@include authors.texi
|
|
|
|
@ignore
|
|
|
|
@setfilename ffmpeg
|
|
@settitle ffmpeg video converter
|
|
|
|
@end ignore
|
|
|
|
@bye
|