@chapter Encoders @c man begin ENCODERS Encoders are configured elements in FFmpeg which allow the encoding of multimedia streams. When you configure your FFmpeg build, all the supported native encoders are enabled by default. Encoders requiring an external library must be enabled manually via the corresponding @code{--enable-lib} option. You can list all available encoders using the configure option @code{--list-encoders}. You can disable all the encoders with the configure option @code{--disable-encoders} and selectively enable / disable single encoders with the options @code{--enable-encoder=@var{ENCODER}} / @code{--disable-encoder=@var{ENCODER}}. The option @code{-encoders} of the ff* tools will display the list of enabled encoders. @c man end ENCODERS @chapter Audio Encoders @c man begin AUDIO ENCODERS A description of some of the currently available audio encoders follows. @anchor{aacenc} @section aac Advanced Audio Coding (AAC) encoder. This encoder is the default AAC encoder, natively implemented into FFmpeg. @subsection Options @table @option @item b Set bit rate in bits/s. Setting this automatically activates constant bit rate (CBR) mode. If this option is unspecified it is set to 128kbps. @item q Set quality for variable bit rate (VBR) mode. This option is valid only using the @command{ffmpeg} command-line tool. For library interface users, use @option{global_quality}. @item cutoff Set cutoff frequency. If unspecified will allow the encoder to dynamically adjust the cutoff to improve clarity on low bitrates. @item aac_coder Set AAC encoder coding method. Possible values: @table @samp @item twoloop Two loop searching (TLS) method. This method first sets quantizers depending on band thresholds and then tries to find an optimal combination by adding or subtracting a specific value from all quantizers and adjusting some individual quantizer a little. Will tune itself based on whether @option{aac_is}, @option{aac_ms} and @option{aac_pns} are enabled. @item anmr Average noise to mask ratio (ANMR) trellis-based solution. This is an experimental coder which currently produces a lower quality, is more unstable and is slower than the default twoloop coder but has potential. Currently has no support for the @option{aac_is} or @option{aac_pns} options. Not currently recommended. @item fast Constant quantizer method. Uses a cheaper version of twoloop algorithm that doesn't try to do as many clever adjustments. Worse with low bitrates (less than 64kbps), but is better and much faster at higher bitrates. This is the default choice for a coder @end table @item aac_ms Sets mid/side coding mode. The default value of "auto" will automatically use M/S with bands which will benefit from such coding. Can be forced for all bands using the value "enable", which is mainly useful for debugging or disabled using "disable". @item aac_is Sets intensity stereo coding tool usage. By default, it's enabled and will automatically toggle IS for similar pairs of stereo bands if it's beneficial. Can be disabled for debugging by setting the value to "disable". @item aac_pns Uses perceptual noise substitution to replace low entropy high frequency bands with imperceptible white noise during the decoding process. By default, it's enabled, but can be disabled for debugging purposes by using "disable". @item aac_tns Enables the use of a multitap FIR filter which spans through the high frequency bands to hide quantization noise during the encoding process and is reverted by the decoder. As well as decreasing unpleasant artifacts in the high range this also reduces the entropy in the high bands and allows for more bits to be used by the mid-low bands. By default it's enabled but can be disabled for debugging by setting the option to "disable". @item aac_ltp Enables the use of the long term prediction extension which increases coding efficiency in very low bandwidth situations such as encoding of voice or solo piano music by extending constant harmonic peaks in bands throughout frames. This option is implied by profile:a aac_low and is incompatible with aac_pred. Use in conjunction with @option{-ar} to decrease the samplerate. @item aac_pred Enables the use of a more traditional style of prediction where the spectral coefficients transmitted are replaced by the difference of the current coefficients minus the previous "predicted" coefficients. In theory and sometimes in practice this can improve quality for low to mid bitrate audio. This option implies the aac_main profile and is incompatible with aac_ltp. @item profile Sets the encoding profile, possible values: @table @samp @item aac_low The default, AAC "Low-complexity" profile. Is the most compatible and produces decent quality. @item mpeg2_aac_low Equivalent to @code{-profile:a aac_low -aac_pns 0}. PNS was introduced with the MPEG4 specifications. @item aac_ltp Long term prediction profile, is enabled by and will enable the @option{aac_ltp} option. Introduced in MPEG4. @item aac_main Main-type prediction profile, is enabled by and will enable the @option{aac_pred} option. Introduced in MPEG2. @end table If this option is unspecified it is set to @samp{aac_low}. @end table @section ac3 and ac3_fixed AC-3 audio encoders. These encoders implement part of ATSC A/52:2010 and ETSI TS 102 366, as well as the undocumented RealAudio 3 (a.k.a. dnet). The @var{ac3} encoder uses floating-point math, while the @var{ac3_fixed} encoder only uses fixed-point integer math. This does not mean that one is always faster, just that one or the other may be better suited to a particular system. The floating-point encoder will generally produce better quality audio for a given bitrate. The @var{ac3_fixed} encoder is not the default codec for any of the output formats, so it must be specified explicitly using the option @code{-acodec ac3_fixed} in order to use it. @subsection AC-3 Metadata The AC-3 metadata options are used to set parameters that describe the audio, but in most cases do not affect the audio encoding itself. Some of the options do directly affect or influence the decoding and playback of the resulting bitstream, while others are just for informational purposes. A few of the options will add bits to the output stream that could otherwise be used for audio data, and will thus affect the quality of the output. Those will be indicated accordingly with a note in the option list below. These parameters are described in detail in several publicly-available documents. @itemize @item @uref{http://www.atsc.org/cms/standards/a_52-2010.pdf,A/52:2010 - Digital Audio Compression (AC-3) (E-AC-3) Standard} @item @uref{http://www.atsc.org/cms/standards/a_54a_with_corr_1.pdf,A/54 - Guide to the Use of the ATSC Digital Television Standard} @item @uref{http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/18_Metadata.Guide.pdf,Dolby Metadata Guide} @item @uref{http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/46_DDEncodingGuidelines.pdf,Dolby Digital Professional Encoding Guidelines} @end itemize @subsubsection Metadata Control Options @table @option @item -per_frame_metadata @var{boolean} Allow Per-Frame Metadata. Specifies if the encoder should check for changing metadata for each frame. @table @option @item 0 The metadata values set at initialization will be used for every frame in the stream. (default) @item 1 Metadata values can be changed before encoding each frame. @end table @end table @subsubsection Downmix Levels @table @option @item -center_mixlev @var{level} Center Mix Level. The amount of gain the decoder should apply to the center channel when downmixing to stereo. This field will only be written to the bitstream if a center channel is present. The value is specified as a scale factor. There are 3 valid values: @table @option @item 0.707 Apply -3dB gain @item 0.595 Apply -4.5dB gain (default) @item 0.500 Apply -6dB gain @end table @item -surround_mixlev @var{level} Surround Mix Level. The amount of gain the decoder should apply to the surround channel(s) when downmixing to stereo. This field will only be written to the bitstream if one or more surround channels are present. The value is specified as a scale factor. There are 3 valid values: @table @option @item 0.707 Apply -3dB gain @item 0.500 Apply -6dB gain (default) @item 0.000 Silence Surround Channel(s) @end table @end table @subsubsection Audio Production Information Audio Production Information is optional information describing the mixing environment. Either none or both of the fields are written to the bitstream. @table @option @item -mixing_level @var{number} Mixing Level. Specifies peak sound pressure level (SPL) in the production environment when the mix was mastered. Valid values are 80 to 111, or -1 for unknown or not indicated. The default value is -1, but that value cannot be used if the Audio Production Information is written to the bitstream. Therefore, if the @code{room_type} option is not the default value, the @code{mixing_level} option must not be -1. @item -room_type @var{type} Room Type. Describes the equalization used during the final mixing session at the studio or on the dubbing stage. A large room is a dubbing stage with the industry standard X-curve equalization; a small room has flat equalization. This field will not be written to the bitstream if both the @code{mixing_level} option and the @code{room_type} option have the default values. @table @option @item 0 @itemx notindicated Not Indicated (default) @item 1 @itemx large Large Room @item 2 @itemx small Small Room @end table @end table @subsubsection Other Metadata Options @table @option @item -copyright @var{boolean} Copyright Indicator. Specifies whether a copyright exists for this audio. @table @option @item 0 @itemx off No Copyright Exists (default) @item 1 @itemx on Copyright Exists @end table @item -dialnorm @var{value} Dialogue Normalization. Indicates how far the average dialogue level of the program is below digital 100% full scale (0 dBFS). This parameter determines a level shift during audio reproduction that sets the average volume of the dialogue to a preset level. The goal is to match volume level between program sources. A value of -31dB will result in no volume level change, relative to the source volume, during audio reproduction. Valid values are whole numbers in the range -31 to -1, with -31 being the default. @item -dsur_mode @var{mode} Dolby Surround Mode. Specifies whether the stereo signal uses Dolby Surround (Pro Logic). This field will only be written to the bitstream if the audio stream is stereo. Using this option does @b{NOT} mean the encoder will actually apply Dolby Surround processing. @table @option @item 0 @itemx notindicated Not Indicated (default) @item 1 @itemx off Not Dolby Surround Encoded @item 2 @itemx on Dolby Surround Encoded @end table @item -original @var{boolean} Original Bit Stream Indicator. Specifies whether this audio is from the original source and not a copy. @table @option @item 0 @itemx off Not Original Source @item 1 @itemx on Original Source (default) @end table @end table @subsection Extended Bitstream Information The extended bitstream options are part of the Alternate Bit Stream Syntax as specified in Annex D of the A/52:2010 standard. It is grouped into 2 parts. If any one parameter in a group is specified, all values in that group will be written to the bitstream. Default values are used for those that are written but have not been specified. If the mixing levels are written, the decoder will use these values instead of the ones specified in the @code{center_mixlev} and @code{surround_mixlev} options if it supports the Alternate Bit Stream Syntax. @subsubsection Extended Bitstream Information - Part 1 @table @option @item -dmix_mode @var{mode} Preferred Stereo Downmix Mode. Allows the user to select either Lt/Rt (Dolby Surround) or Lo/Ro (normal stereo) as the preferred stereo downmix mode. @table @option @item 0 @itemx notindicated Not Indicated (default) @item 1 @itemx ltrt Lt/Rt Downmix Preferred @item 2 @itemx loro Lo/Ro Downmix Preferred @end table @item -ltrt_cmixlev @var{level} Lt/Rt Center Mix Level. The amount of gain the decoder should apply to the center channel when downmixing to stereo in Lt/Rt mode. @table @option @item 1.414 Apply +3dB gain @item 1.189 Apply +1.5dB gain @item 1.000 Apply 0dB gain @item 0.841 Apply -1.5dB gain @item 0.707 Apply -3.0dB gain @item 0.595 Apply -4.5dB gain (default) @item 0.500 Apply -6.0dB gain @item 0.000 Silence Center Channel @end table @item -ltrt_surmixlev @var{level} Lt/Rt Surround Mix Level. The amount of gain the decoder should apply to the surround channel(s) when downmixing to stereo in Lt/Rt mode. @table @option @item 0.841 Apply -1.5dB gain @item 0.707 Apply -3.0dB gain @item 0.595 Apply -4.5dB gain @item 0.500 Apply -6.0dB gain (default) @item 0.000 Silence Surround Channel(s) @end table @item -loro_cmixlev @var{level} Lo/Ro Center Mix Level. The amount of gain the decoder should apply to the center channel when downmixing to stereo in Lo/Ro mode. @table @option @item 1.414 Apply +3dB gain @item 1.189 Apply +1.5dB gain @item 1.000 Apply 0dB gain @item 0.841 Apply -1.5dB gain @item 0.707 Apply -3.0dB gain @item 0.595 Apply -4.5dB gain (default) @item 0.500 Apply -6.0dB gain @item 0.000 Silence Center Channel @end table @item -loro_surmixlev @var{level} Lo/Ro Surround Mix Level. The amount of gain the decoder should apply to the surround channel(s) when downmixing to stereo in Lo/Ro mode. @table @option @item 0.841 Apply -1.5dB gain @item 0.707 Apply -3.0dB gain @item 0.595 Apply -4.5dB gain @item 0.500 Apply -6.0dB gain (default) @item 0.000 Silence Surround Channel(s) @end table @end table @subsubsection Extended Bitstream Information - Part 2 @table @option @item -dsurex_mode @var{mode} Dolby Surround EX Mode. Indicates whether the stream uses Dolby Surround EX (7.1 matrixed to 5.1). Using this option does @b{NOT} mean the encoder will actually apply Dolby Surround EX processing. @table @option @item 0 @itemx notindicated Not Indicated (default) @item 1 @itemx on Dolby Surround EX Off @item 2 @itemx off Dolby Surround EX On @end table @item -dheadphone_mode @var{mode} Dolby Headphone Mode. Indicates whether the stream uses Dolby Headphone encoding (multi-channel matrixed to 2.0 for use with headphones). Using this option does @b{NOT} mean the encoder will actually apply Dolby Headphone processing. @table @option @item 0 @itemx notindicated Not Indicated (default) @item 1 @itemx on Dolby Headphone Off @item 2 @itemx off Dolby Headphone On @end table @item -ad_conv_type @var{type} A/D Converter Type. Indicates whether the audio has passed through HDCD A/D conversion. @table @option @item 0 @itemx standard Standard A/D Converter (default) @item 1 @itemx hdcd HDCD A/D Converter @end table @end table @subsection Other AC-3 Encoding Options @table @option @item -stereo_rematrixing @var{boolean} Stereo Rematrixing. Enables/Disables use of rematrixing for stereo input. This is an optional AC-3 feature that increases quality by selectively encoding the left/right channels as mid/side. This option is enabled by default, and it is highly recommended that it be left as enabled except for testing purposes. @item cutoff @var{frequency} Set lowpass cutoff frequency. If unspecified, the encoder selects a default determined by various other encoding parameters. @end table @subsection Floating-Point-Only AC-3 Encoding Options These options are only valid for the floating-point encoder and do not exist for the fixed-point encoder due to the corresponding features not being implemented in fixed-point. @table @option @item -channel_coupling @var{boolean} Enables/Disables use of channel coupling, which is an optional AC-3 feature that increases quality by combining high frequency information from multiple channels into a single channel. The per-channel high frequency information is sent with less accuracy in both the frequency and time domains. This allows more bits to be used for lower frequencies while preserving enough information to reconstruct the high frequencies. This option is enabled by default for the floating-point encoder and should generally be left as enabled except for testing purposes or to increase encoding speed. @table @option @item -1 @itemx auto Selected by Encoder (default) @item 0 @itemx off Disable Channel Coupling @item 1 @itemx on Enable Channel Coupling @end table @item -cpl_start_band @var{number} Coupling Start Band. Sets the channel coupling start band, from 1 to 15. If a value higher than the bandwidth is used, it will be reduced to 1 less than the coupling end band. If @var{auto} is used, the start band will be determined by the encoder based on the bit rate, sample rate, and channel layout. This option has no effect if channel coupling is disabled. @table @option @item -1 @itemx auto Selected by Encoder (default) @end table @end table @anchor{flac} @section flac FLAC (Free Lossless Audio Codec) Encoder @subsection Options The following options are supported by FFmpeg's flac encoder. @table @option @item compression_level Sets the compression level, which chooses defaults for many other options if they are not set explicitly. Valid values are from 0 to 12, 5 is the default. @item frame_size Sets the size of the frames in samples per channel. @item lpc_coeff_precision Sets the LPC coefficient precision, valid values are from 1 to 15, 15 is the default. @item lpc_type Sets the first stage LPC algorithm @table @samp @item none LPC is not used @item fixed fixed LPC coefficients @item levinson @item cholesky @end table @item lpc_passes Number of passes to use for Cholesky factorization during LPC analysis @item min_partition_order The minimum partition order @item max_partition_order The maximum partition order @item prediction_order_method @table @samp @item estimation @item 2level @item 4level @item 8level @item search Bruteforce search @item log @end table @item ch_mode Channel mode @table @samp @item auto The mode is chosen automatically for each frame @item indep Channels are independently coded @item left_side @item right_side @item mid_side @end table @item exact_rice_parameters Chooses if rice parameters are calculated exactly or approximately. if set to 1 then they are chosen exactly, which slows the code down slightly and improves compression slightly. @item multi_dim_quant Multi Dimensional Quantization. If set to 1 then a 2nd stage LPC algorithm is applied after the first stage to finetune the coefficients. This is quite slow and slightly improves compression. @end table @anchor{opusenc} @section opus Opus encoder. This is a native FFmpeg encoder for the Opus format. Currently its in development and only implements the CELT part of the codec. Its quality is usually worse and at best is equal to the libopus encoder. @subsection Options @table @option @item b Set bit rate in bits/s. If unspecified it uses the number of channels and the layout to make a good guess. @item opus_delay Sets the maximum delay in milliseconds. Lower delays than 20ms will very quickly decrease quality. @end table @anchor{libfdk-aac-enc} @section libfdk_aac libfdk-aac AAC (Advanced Audio Coding) encoder wrapper. The libfdk-aac library is based on the Fraunhofer FDK AAC code from the Android project. Requires the presence of the libfdk-aac headers and library during configuration. You need to explicitly configure the build with @code{--enable-libfdk-aac}. The library is also incompatible with GPL, so if you allow the use of GPL, you should configure with @code{--enable-gpl --enable-nonfree --enable-libfdk-aac}. This encoder has support for the AAC-HE profiles. VBR encoding, enabled through the @option{vbr} or @option{flags +qscale} options, is experimental and only works with some combinations of parameters. Support for encoding 7.1 audio is only available with libfdk-aac 0.1.3 or higher. For more information see the fdk-aac project at @url{http://sourceforge.net/p/opencore-amr/fdk-aac/}. @subsection Options The following options are mapped on the shared FFmpeg codec options. @table @option @item b Set bit rate in bits/s. If the bitrate is not explicitly specified, it is automatically set to a suitable value depending on the selected profile. In case VBR mode is enabled the option is ignored. @item ar Set audio sampling rate (in Hz). @item channels Set the number of audio channels. @item flags +qscale Enable fixed quality, VBR (Variable Bit Rate) mode. Note that VBR is implicitly enabled when the @option{vbr} value is positive. @item cutoff Set cutoff frequency. If not specified (or explicitly set to 0) it will use a value automatically computed by the library. Default value is 0. @item profile Set audio profile. The following profiles are recognized: @table @samp @item aac_low Low Complexity AAC (LC) @item aac_he High Efficiency AAC (HE-AAC) @item aac_he_v2 High Efficiency AAC version 2 (HE-AACv2) @item aac_ld Low Delay AAC (LD) @item aac_eld Enhanced Low Delay AAC (ELD) @end table If not specified it is set to @samp{aac_low}. @end table The following are private options of the libfdk_aac encoder. @table @option @item afterburner Enable afterburner feature if set to 1, disabled if set to 0. This improves the quality but also the required processing power. Default value is 1. @item eld_sbr Enable SBR (Spectral Band Replication) for ELD if set to 1, disabled if set to 0. Default value is 0. @item eld_v2 Enable ELDv2 (LD-MPS extension for ELD stereo signals) for ELDv2 if set to 1, disabled if set to 0. Note that option is available when fdk-aac version (AACENCODER_LIB_VL0.AACENCODER_LIB_VL1.AACENCODER_LIB_VL2) > (4.0.0). Default value is 0. @item signaling Set SBR/PS signaling style. It can assume one of the following values: @table @samp @item default choose signaling implicitly (explicit hierarchical by default, implicit if global header is disabled) @item implicit implicit backwards compatible signaling @item explicit_sbr explicit SBR, implicit PS signaling @item explicit_hierarchical explicit hierarchical signaling @end table Default value is @samp{default}. @item latm Output LATM/LOAS encapsulated data if set to 1, disabled if set to 0. Default value is 0. @item header_period Set StreamMuxConfig and PCE repetition period (in frames) for sending in-band configuration buffers within LATM/LOAS transport layer. Must be a 16-bits non-negative integer. Default value is 0. @item vbr Set VBR mode, from 1 to 5. 1 is lowest quality (though still pretty good) and 5 is highest quality. A value of 0 will disable VBR, and CBR (Constant Bit Rate) is enabled. Currently only the @samp{aac_low} profile supports VBR encoding. VBR modes 1-5 correspond to roughly the following average bit rates: @table @samp @item 1 32 kbps/channel @item 2 40 kbps/channel @item 3 48-56 kbps/channel @item 4 64 kbps/channel @item 5 about 80-96 kbps/channel @end table Default value is 0. @end table @subsection Examples @itemize @item Use @command{ffmpeg} to convert an audio file to VBR AAC in an M4A (MP4) container: @example ffmpeg -i input.wav -codec:a libfdk_aac -vbr 3 output.m4a @end example @item Use @command{ffmpeg} to convert an audio file to CBR 64k kbps AAC, using the High-Efficiency AAC profile: @example ffmpeg -i input.wav -c:a libfdk_aac -profile:a aac_he -b:a 64k output.m4a @end example @end itemize @anchor{libmp3lame} @section libmp3lame LAME (Lame Ain't an MP3 Encoder) MP3 encoder wrapper. Requires the presence of the libmp3lame headers and library during configuration. You need to explicitly configure the build with @code{--enable-libmp3lame}. See @ref{libshine} for a fixed-point MP3 encoder, although with a lower quality. @subsection Options The following options are supported by the libmp3lame wrapper. The @command{lame}-equivalent of the options are listed in parentheses. @table @option @item b (@emph{-b}) Set bitrate expressed in bits/s for CBR or ABR. LAME @code{bitrate} is expressed in kilobits/s. @item q (@emph{-V}) Set constant quality setting for VBR. This option is valid only using the @command{ffmpeg} command-line tool. For library interface users, use @option{global_quality}. @item compression_level (@emph{-q}) Set algorithm quality. Valid arguments are integers in the 0-9 range, with 0 meaning highest quality but slowest, and 9 meaning fastest while producing the worst quality. @item cutoff (@emph{--lowpass}) Set lowpass cutoff frequency. If unspecified, the encoder dynamically adjusts the cutoff. @item reservoir Enable use of bit reservoir when set to 1. Default value is 1. LAME has this enabled by default, but can be overridden by use @option{--nores} option. @item joint_stereo (@emph{-m j}) Enable the encoder to use (on a frame by frame basis) either L/R stereo or mid/side stereo. Default value is 1. @item abr (@emph{--abr}) Enable the encoder to use ABR when set to 1. The @command{lame} @option{--abr} sets the target bitrate, while this options only tells FFmpeg to use ABR still relies on @option{b} to set bitrate. @end table @section libopencore-amrnb OpenCORE Adaptive Multi-Rate Narrowband encoder. Requires the presence of the libopencore-amrnb headers and library during configuration. You need to explicitly configure the build with @code{--enable-libopencore-amrnb --enable-version3}. This is a mono-only encoder. Officially it only supports 8000Hz sample rate, but you can override it by setting @option{strict} to @samp{unofficial} or lower. @subsection Options @table @option @item b Set bitrate in bits per second. Only the following bitrates are supported, otherwise libavcodec will round to the nearest valid bitrate. @table @option @item 4750 @item 5150 @item 5900 @item 6700 @item 7400 @item 7950 @item 10200 @item 12200 @end table @item dtx Allow discontinuous transmission (generate comfort noise) when set to 1. The default value is 0 (disabled). @end table @section libopus libopus Opus Interactive Audio Codec encoder wrapper. Requires the presence of the libopus headers and library during configuration. You need to explicitly configure the build with @code{--enable-libopus}. @subsection Option Mapping Most libopus options are modelled after the @command{opusenc} utility from opus-tools. The following is an option mapping chart describing options supported by the libopus wrapper, and their @command{opusenc}-equivalent in parentheses. @table @option @item b (@emph{bitrate}) Set the bit rate in bits/s. FFmpeg's @option{b} option is expressed in bits/s, while @command{opusenc}'s @option{bitrate} in kilobits/s. @item vbr (@emph{vbr}, @emph{hard-cbr}, and @emph{cvbr}) Set VBR mode. The FFmpeg @option{vbr} option has the following valid arguments, with the @command{opusenc} equivalent options in parentheses: @table @samp @item off (@emph{hard-cbr}) Use constant bit rate encoding. @item on (@emph{vbr}) Use variable bit rate encoding (the default). @item constrained (@emph{cvbr}) Use constrained variable bit rate encoding. @end table @item compression_level (@emph{comp}) Set encoding algorithm complexity. Valid options are integers in the 0-10 range. 0 gives the fastest encodes but lower quality, while 10 gives the highest quality but slowest encoding. The default is 10. @item frame_duration (@emph{framesize}) Set maximum frame size, or duration of a frame in milliseconds. The argument must be exactly the following: 2.5, 5, 10, 20, 40, 60. Smaller frame sizes achieve lower latency but less quality at a given bitrate. Sizes greater than 20ms are only interesting at fairly low bitrates. The default is 20ms. @item packet_loss (@emph{expect-loss}) Set expected packet loss percentage. The default is 0. @item application (N.A.) Set intended application type. Valid options are listed below: @table @samp @item voip Favor improved speech intelligibility. @item audio Favor faithfulness to the input (the default). @item lowdelay Restrict to only the lowest delay modes. @end table @item cutoff (N.A.) Set cutoff bandwidth in Hz. The argument must be exactly one of the following: 4000, 6000, 8000, 12000, or 20000, corresponding to narrowband, mediumband, wideband, super wideband, and fullband respectively. The default is 0 (cutoff disabled). @item mapping_family (@emph{mapping_family}) Set channel mapping family to be used by the encoder. The default value of -1 uses mapping family 0 for mono and stereo inputs, and mapping family 1 otherwise. The default also disables the surround masking and LFE bandwidth optimzations in libopus, and requires that the input contains 8 channels or fewer. Other values include 0 for mono and stereo, 1 for surround sound with masking and LFE bandwidth optimizations, and 255 for independent streams with an unspecified channel layout. @item apply_phase_inv (N.A.) (requires libopus >= 1.2) If set to 0, disables the use of phase inversion for intensity stereo, improving the quality of mono downmixes, but slightly reducing normal stereo quality. The default is 1 (phase inversion enabled). @end table @anchor{libshine} @section libshine Shine Fixed-Point MP3 encoder wrapper. Shine is a fixed-point MP3 encoder. It has a far better performance on platforms without an FPU, e.g. armel CPUs, and some phones and tablets. However, as it is more targeted on performance than quality, it is not on par with LAME and other production-grade encoders quality-wise. Also, according to the project's homepage, this encoder may not be free of bugs as the code was written a long time ago and the project was dead for at least 5 years. This encoder only supports stereo and mono input. This is also CBR-only. The original project (last updated in early 2007) is at @url{http://sourceforge.net/projects/libshine-fxp/}. We only support the updated fork by the Savonet/Liquidsoap project at @url{https://github.com/savonet/shine}. Requires the presence of the libshine headers and library during configuration. You need to explicitly configure the build with @code{--enable-libshine}. See also @ref{libmp3lame}. @subsection Options The following options are supported by the libshine wrapper. The @command{shineenc}-equivalent of the options are listed in parentheses. @table @option @item b (@emph{-b}) Set bitrate expressed in bits/s for CBR. @command{shineenc} @option{-b} option is expressed in kilobits/s. @end table @section libtwolame TwoLAME MP2 encoder wrapper. Requires the presence of the libtwolame headers and library during configuration. You need to explicitly configure the build with @code{--enable-libtwolame}. @subsection Options The following options are supported by the libtwolame wrapper. The @command{twolame}-equivalent options follow the FFmpeg ones and are in parentheses. @table @option @item b (@emph{-b}) Set bitrate expressed in bits/s for CBR. @command{twolame} @option{b} option is expressed in kilobits/s. Default value is 128k. @item q (@emph{-V}) Set quality for experimental VBR support. Maximum value range is from -50 to 50, useful range is from -10 to 10. The higher the value, the better the quality. This option is valid only using the @command{ffmpeg} command-line tool. For library interface users, use @option{global_quality}. @item mode (@emph{--mode}) Set the mode of the resulting audio. Possible values: @table @samp @item auto Choose mode automatically based on the input. This is the default. @item stereo Stereo @item joint_stereo Joint stereo @item dual_channel Dual channel @item mono Mono @end table @item psymodel (@emph{--psyc-mode}) Set psychoacoustic model to use in encoding. The argument must be an integer between -1 and 4, inclusive. The higher the value, the better the quality. The default value is 3. @item energy_levels (@emph{--energy}) Enable energy levels extensions when set to 1. The default value is 0 (disabled). @item error_protection (@emph{--protect}) Enable CRC error protection when set to 1. The default value is 0 (disabled). @item copyright (@emph{--copyright}) Set MPEG audio copyright flag when set to 1. The default value is 0 (disabled). @item original (@emph{--original}) Set MPEG audio original flag when set to 1. The default value is 0 (disabled). @end table @section libvo-amrwbenc VisualOn Adaptive Multi-Rate Wideband encoder. Requires the presence of the libvo-amrwbenc headers and library during configuration. You need to explicitly configure the build with @code{--enable-libvo-amrwbenc --enable-version3}. This is a mono-only encoder. Officially it only supports 16000Hz sample rate, but you can override it by setting @option{strict} to @samp{unofficial} or lower. @subsection Options @table @option @item b Set bitrate in bits/s. Only the following bitrates are supported, otherwise libavcodec will round to the nearest valid bitrate. @table @samp @item 6600 @item 8850 @item 12650 @item 14250 @item 15850 @item 18250 @item 19850 @item 23050 @item 23850 @end table @item dtx Allow discontinuous transmission (generate comfort noise) when set to 1. The default value is 0 (disabled). @end table @section libvorbis libvorbis encoder wrapper. Requires the presence of the libvorbisenc headers and library during configuration. You need to explicitly configure the build with @code{--enable-libvorbis}. @subsection Options The following options are supported by the libvorbis wrapper. The @command{oggenc}-equivalent of the options are listed in parentheses. To get a more accurate and extensive documentation of the libvorbis options, consult the libvorbisenc's and @command{oggenc}'s documentations. See @url{http://xiph.org/vorbis/}, @url{http://wiki.xiph.org/Vorbis-tools}, and oggenc(1). @table @option @item b (@emph{-b}) Set bitrate expressed in bits/s for ABR. @command{oggenc} @option{-b} is expressed in kilobits/s. @item q (@emph{-q}) Set constant quality setting for VBR. The value should be a float number in the range of -1.0 to 10.0. The higher the value, the better the quality. The default value is @samp{3.0}. This option is valid only using the @command{ffmpeg} command-line tool. For library interface users, use @option{global_quality}. @item cutoff (@emph{--advanced-encode-option lowpass_frequency=N}) Set cutoff bandwidth in Hz, a value of 0 disables cutoff. @command{oggenc}'s related option is expressed in kHz. The default value is @samp{0} (cutoff disabled). @item minrate (@emph{-m}) Set minimum bitrate expressed in bits/s. @command{oggenc} @option{-m} is expressed in kilobits/s. @item maxrate (@emph{-M}) Set maximum bitrate expressed in bits/s. @command{oggenc} @option{-M} is expressed in kilobits/s. This only has effect on ABR mode. @item iblock (@emph{--advanced-encode-option impulse_noisetune=N}) Set noise floor bias for impulse blocks. The value is a float number from -15.0 to 0.0. A negative bias instructs the encoder to pay special attention to the crispness of transients in the encoded audio. The tradeoff for better transient response is a higher bitrate. @end table @anchor{libwavpack} @section libwavpack A wrapper providing WavPack encoding through libwavpack. Only lossless mode using 32-bit integer samples is supported currently. Requires the presence of the libwavpack headers and library during configuration. You need to explicitly configure the build with @code{--enable-libwavpack}. Note that a libavcodec-native encoder for the WavPack codec exists so users can encode audios with this codec without using this encoder. See @ref{wavpackenc}. @subsection Options @command{wavpack} command line utility's corresponding options are listed in parentheses, if any. @table @option @item frame_size (@emph{--blocksize}) Default is 32768. @item compression_level Set speed vs. compression tradeoff. Acceptable arguments are listed below: @table @samp @item 0 (@emph{-f}) Fast mode. @item 1 Normal (default) settings. @item 2 (@emph{-h}) High quality. @item 3 (@emph{-hh}) Very high quality. @item 4-8 (@emph{-hh -x}@var{EXTRAPROC}) Same as @samp{3}, but with extra processing enabled. @samp{4} is the same as @option{-x2} and @samp{8} is the same as @option{-x6}. @end table @end table @anchor{mjpegenc} @section mjpeg Motion JPEG encoder. @subsection Options @table @option @item huffman Set the huffman encoding strategy. Possible values: @table @samp @item default Use the default huffman tables. This is the default strategy. @item optimal Compute and use optimal huffman tables. @end table @end table @anchor{wavpackenc} @section wavpack WavPack lossless audio encoder. This is a libavcodec-native WavPack encoder. There is also an encoder based on libwavpack, but there is virtually no reason to use that encoder. See also @ref{libwavpack}. @subsection Options The equivalent options for @command{wavpack} command line utility are listed in parentheses. @subsubsection Shared options The following shared options are effective for this encoder. Only special notes about this particular encoder will be documented here. For the general meaning of the options, see @ref{codec-options,,the Codec Options chapter}. @table @option @item frame_size (@emph{--blocksize}) For this encoder, the range for this option is between 128 and 131072. Default is automatically decided based on sample rate and number of channel. For the complete formula of calculating default, see @file{libavcodec/wavpackenc.c}. @item compression_level (@emph{-f}, @emph{-h}, @emph{-hh}, and @emph{-x}) This option's syntax is consistent with @ref{libwavpack}'s. @end table @subsubsection Private options @table @option @item joint_stereo (@emph{-j}) Set whether to enable joint stereo. Valid values are: @table @samp @item on (@emph{1}) Force mid/side audio encoding. @item off (@emph{0}) Force left/right audio encoding. @item auto Let the encoder decide automatically. @end table @item optimize_mono Set whether to enable optimization for mono. This option is only effective for non-mono streams. Available values: @table @samp @item on enabled @item off disabled @end table @end table @c man end AUDIO ENCODERS @chapter Video Encoders @c man begin VIDEO ENCODERS A description of some of the currently available video encoders follows. @section Hap Vidvox Hap video encoder. @subsection Options @table @option @item format @var{integer} Specifies the Hap format to encode. @table @option @item hap @item hap_alpha @item hap_q @end table Default value is @option{hap}. @item chunks @var{integer} Specifies the number of chunks to split frames into, between 1 and 64. This permits multithreaded decoding of large frames, potentially at the cost of data-rate. The encoder may modify this value to divide frames evenly. Default value is @var{1}. @item compressor @var{integer} Specifies the second-stage compressor to use. If set to @option{none}, @option{chunks} will be limited to 1, as chunked uncompressed frames offer no benefit. @table @option @item none @item snappy @end table Default value is @option{snappy}. @end table @section jpeg2000 The native jpeg 2000 encoder is lossy by default, the @code{-q:v} option can be used to set the encoding quality. Lossless encoding can be selected with @code{-pred 1}. @subsection Options @table @option @item format @var{integer} Can be set to either @code{j2k} or @code{jp2} (the default) that makes it possible to store non-rgb pix_fmts. @item tile_width @var{integer} Sets tile width. Range is 1 to 1073741824. Default is 256. @item tile_height @var{integer} Sets tile height. Range is 1 to 1073741824. Default is 256. @item pred @var{integer} Allows setting the discrete wavelet transform (DWT) type @table @option @item dwt97int (Lossy) @item dwt53 (Lossless) @end table Default is @code{dwt97int} @item sop @var{boolean} Enable this to add SOP marker at the start of each packet. Disabled by default. @item eph @var{boolean} Enable this to add EPH marker at the end of each packet header. Disabled by default. @item prog @var{integer} Sets the progression order to be used by the encoder. Possible values are: @table @option @item lrcp @item rlcp @item rpcl @item pcrl @item cprl @end table Set to @code{lrcp} by default. @item layer_rates @var{string} By default, when this option is not used, compression is done using the quality metric. This option allows for compression using compression ratio. The compression ratio for each level could be specified. The compression ratio of a layer @code{l} species the what ratio of total file size is contained in the first @code{l} layers. Example usage: @example ffmpeg -i input.bmp -c:v jpeg2000 -layer_rates "100,10,1" output.j2k @end example This would compress the image to contain 3 layers, where the data contained in the first layer would be compressed by 1000 times, compressed by 100 in the first two layers, and shall contain all data while using all 3 layers. @end table @section librav1e rav1e AV1 encoder wrapper. Requires the presence of the rav1e headers and library during configuration. You need to explicitly configure the build with @code{--enable-librav1e}. @subsection Options @table @option @item qmax Sets the maximum quantizer to use when using bitrate mode. @item qmin Sets the minimum quantizer to use when using bitrate mode. @item qp Uses quantizer mode to encode at the given quantizer (0-255). @item speed Selects the speed preset (0-10) to encode with. @item tiles Selects how many tiles to encode with. @item tile-rows Selects how many rows of tiles to encode with. @item tile-columns Selects how many columns of tiles to encode with. @item rav1e-params Set rav1e options using a list of @var{key}=@var{value} pairs separated by ":". See @command{rav1e --help} for a list of options. For example to specify librav1e encoding options with @option{-rav1e-params}: @example ffmpeg -i input -c:v librav1e -b:v 500K -rav1e-params speed=5:low_latency=true output.mp4 @end example @end table @section libaom-av1 libaom AV1 encoder wrapper. Requires the presence of the libaom headers and library during configuration. You need to explicitly configure the build with @code{--enable-libaom}. @subsection Options The wrapper supports the following standard libavcodec options: @table @option @item b Set bitrate target in bits/second. By default this will use variable-bitrate mode. If @option{maxrate} and @option{minrate} are also set to the same value then it will use constant-bitrate mode, otherwise if @option{crf} is set as well then it will use constrained-quality mode. @item g keyint_min Set key frame placement. The GOP size sets the maximum distance between key frames; if zero the output stream will be intra-only. The minimum distance is ignored unless it is the same as the GOP size, in which case key frames will always appear at a fixed interval. Not set by default, so without this option the library has completely free choice about where to place key frames. @item qmin qmax Set minimum/maximum quantisation values. Valid range is from 0 to 63 (warning: this does not match the quantiser values actually used by AV1 - divide by four to map real quantiser values to this range). Defaults to min/max (no constraint). @item minrate maxrate bufsize rc_init_occupancy Set rate control buffering parameters. Not used if not set - defaults to unconstrained variable bitrate. @item threads Set the number of threads to use while encoding. This may require the @option{tiles} or @option{row-mt} options to also be set to actually use the specified number of threads fully. Defaults to the number of hardware threads supported by the host machine. @item profile Set the encoding profile. Defaults to using the profile which matches the bit depth and chroma subsampling of the input. @end table The wrapper also has some specific options: @table @option @item cpu-used Set the quality/encoding speed tradeoff. Valid range is from 0 to 8, higher numbers indicating greater speed and lower quality. The default value is 1, which will be slow and high quality. @item auto-alt-ref Enable use of alternate reference frames. Defaults to the internal default of the library. @item arnr-max-frames (@emph{frames}) Set altref noise reduction max frame count. Default is -1. @item arnr-strength (@emph{strength}) Set altref noise reduction filter strength. Range is -1 to 6. Default is -1. @item aq-mode (@emph{aq-mode}) Set adaptive quantization mode. Possible values: @table @samp @item none (@emph{0}) Disabled. @item variance (@emph{1}) Variance-based. @item complexity (@emph{2}) Complexity-based. @item cyclic (@emph{3}) Cyclic refresh. @end table @item tune (@emph{tune}) Set the distortion metric the encoder is tuned with. Default is @code{psnr}. @table @samp @item psnr (@emph{0}) @item ssim (@emph{1}) @end table @item lag-in-frames Set the maximum number of frames which the encoder may keep in flight at any one time for lookahead purposes. Defaults to the internal default of the library. @item error-resilience Enable error resilience features: @table @option @item default Improve resilience against losses of whole frames. @end table Not enabled by default. @item crf Set the quality/size tradeoff for constant-quality (no bitrate target) and constrained-quality (with maximum bitrate target) modes. Valid range is 0 to 63, higher numbers indicating lower quality and smaller output size. Only used if set; by default only the bitrate target is used. @item static-thresh Set a change threshold on blocks below which they will be skipped by the encoder. Defined in arbitrary units as a nonnegative integer, defaulting to zero (no blocks are skipped). @item drop-threshold Set a threshold for dropping frames when close to rate control bounds. Defined as a percentage of the target buffer - when the rate control buffer falls below this percentage, frames will be dropped until it has refilled above the threshold. Defaults to zero (no frames are dropped). @item denoise-noise-level (@emph{level}) Amount of noise to be removed for grain synthesis. Grain synthesis is disabled if this option is not set or set to 0. @item denoise-block-size (@emph{pixels}) Block size used for denoising for grain synthesis. If not set, AV1 codec uses the default value of 32. @item undershoot-pct (@emph{pct}) Set datarate undershoot (min) percentage of the target bitrate. Range is -1 to 100. Default is -1. @item overshoot-pct (@emph{pct}) Set datarate overshoot (max) percentage of the target bitrate. Range is -1 to 1000. Default is -1. @item minsection-pct (@emph{pct}) Minimum percentage variation of the GOP bitrate from the target bitrate. If minsection-pct is not set, the libaomenc wrapper computes it as follows: @code{(minrate * 100 / bitrate)}. Range is -1 to 100. Default is -1 (unset). @item maxsection-pct (@emph{pct}) Maximum percentage variation of the GOP bitrate from the target bitrate. If maxsection-pct is not set, the libaomenc wrapper computes it as follows: @code{(maxrate * 100 / bitrate)}. Range is -1 to 5000. Default is -1 (unset). @item frame-parallel (@emph{boolean}) Enable frame parallel decodability features. Default is true. @item tiles Set the number of tiles to encode the input video with, as columns x rows. Larger numbers allow greater parallelism in both encoding and decoding, but may decrease coding efficiency. Defaults to the minimum number of tiles required by the size of the input video (this is 1x1 (that is, a single tile) for sizes up to and including 4K). @item tile-columns tile-rows Set the number of tiles as log2 of the number of tile rows and columns. Provided for compatibility with libvpx/VP9. @item row-mt (Requires libaom >= 1.0.0-759-g90a15f4f2) Enable row based multi-threading. Disabled by default. @item enable-cdef (@emph{boolean}) Enable Constrained Directional Enhancement Filter. The libaom-av1 encoder enables CDEF by default. @item enable-restoration (@emph{boolean}) Enable Loop Restoration Filter. Default is true for libaom-av1. @item enable-global-motion (@emph{boolean}) Enable the use of global motion for block prediction. Default is true. @item enable-intrabc (@emph{boolean}) Enable block copy mode for intra block prediction. This mode is useful for screen content. Default is true. @item enable-rect-partitions (@emph{boolean}) (Requires libaom >= v2.0.0) Enable rectangular partitions. Default is true. @item enable-1to4-partitions (@emph{boolean}) (Requires libaom >= v2.0.0) Enable 1:4/4:1 partitions. Default is true. @item enable-ab-partitions (@emph{boolean}) (Requires libaom >= v2.0.0) Enable AB shape partitions. Default is true. @item enable-angle-delta (@emph{boolean}) (Requires libaom >= v2.0.0) Enable angle delta intra prediction. Default is true. @item enable-cfl-intra (@emph{boolean}) (Requires libaom >= v2.0.0) Enable chroma predicted from luma intra prediction. Default is true. @item enable-filter-intra (@emph{boolean}) (Requires libaom >= v2.0.0) Enable filter intra predictor. Default is true. @item enable-intra-edge-filter (@emph{boolean}) (Requires libaom >= v2.0.0) Enable intra edge filter. Default is true. @item enable-smooth-intra (@emph{boolean}) (Requires libaom >= v2.0.0) Enable smooth intra prediction mode. Default is true. @item enable-paeth-intra (@emph{boolean}) (Requires libaom >= v2.0.0) Enable paeth predictor in intra prediction. Default is true. @item enable-palette (@emph{boolean}) (Requires libaom >= v2.0.0) Enable palette prediction mode. Default is true. @item enable-flip-idtx (@emph{boolean}) (Requires libaom >= v2.0.0) Enable extended transform type, including FLIPADST_DCT, DCT_FLIPADST, FLIPADST_FLIPADST, ADST_FLIPADST, FLIPADST_ADST, IDTX, V_DCT, H_DCT, V_ADST, H_ADST, V_FLIPADST, H_FLIPADST. Default is true. @item enable-tx64 (@emph{boolean}) (Requires libaom >= v2.0.0) Enable 64-pt transform. Default is true. @item reduced-tx-type-set (@emph{boolean}) (Requires libaom >= v2.0.0) Use reduced set of transform types. Default is false. @item use-intra-dct-only (@emph{boolean}) (Requires libaom >= v2.0.0) Use DCT only for INTRA modes. Default is false. @item use-inter-dct-only (@emph{boolean}) (Requires libaom >= v2.0.0) Use DCT only for INTER modes. Default is false. @item use-intra-default-tx-only (@emph{boolean}) (Requires libaom >= v2.0.0) Use Default-transform only for INTRA modes. Default is false. @item enable-ref-frame-mvs (@emph{boolean}) (Requires libaom >= v2.0.0) Enable temporal mv prediction. Default is true. @item enable-reduced-reference-set (@emph{boolean}) (Requires libaom >= v2.0.0) Use reduced set of single and compound references. Default is false. @item enable-obmc (@emph{boolean}) (Requires libaom >= v2.0.0) Enable obmc. Default is true. @item enable-dual-filter (@emph{boolean}) (Requires libaom >= v2.0.0) Enable dual filter. Default is true. @item enable-diff-wtd-comp (@emph{boolean}) (Requires libaom >= v2.0.0) Enable difference-weighted compound. Default is true. @item enable-dist-wtd-comp (@emph{boolean}) (Requires libaom >= v2.0.0) Enable distance-weighted compound. Default is true. @item enable-onesided-comp (@emph{boolean}) (Requires libaom >= v2.0.0) Enable one sided compound. Default is true. @item enable-interinter-wedge (@emph{boolean}) (Requires libaom >= v2.0.0) Enable interinter wedge compound. Default is true. @item enable-interintra-wedge (@emph{boolean}) (Requires libaom >= v2.0.0) Enable interintra wedge compound. Default is true. @item enable-masked-comp (@emph{boolean}) (Requires libaom >= v2.0.0) Enable masked compound. Default is true. @item enable-interintra-comp (@emph{boolean}) (Requires libaom >= v2.0.0) Enable interintra compound. Default is true. @item enable-smooth-interintra (@emph{boolean}) (Requires libaom >= v2.0.0) Enable smooth interintra mode. Default is true. @end table @section libsvtav1 SVT-AV1 encoder wrapper. Requires the presence of the SVT-AV1 headers and library during configuration. You need to explicitly configure the build with @code{--enable-libsvtav1}. @subsection Options @table @option @item profile Set the encoding profile. @item level Set the operating point level. @item tier Set the operating point tier. @item rc Set the rate control mode to use. Possible modes: @table @option @item cqp Constant quantizer: use fixed values of qindex (dependent on the frame type) throughout the stream. This mode is the default. @item vbr Variable bitrate: use a target bitrate for the whole stream. @item cvbr Constrained variable bitrate: use a target bitrate for each GOP. @end table @item qmax Set the maximum quantizer to use when using a bitrate mode. @item qmin Set the minimum quantizer to use when using a bitrate mode. @item qp Set the quantizer used in cqp rate control mode (0-63). @item sc_detection Enable scene change detection. @item la_depth Set number of frames to look ahead (0-120). @item preset Set the quality-speed tradeoff, in the range 0 to 8. Higher values are faster but lower quality. Defaults to 8 (highest speed). @item tile_rows Set log2 of the number of rows of tiles to use (0-6). @item tile_columns Set log2 of the number of columns of tiles to use (0-4). @end table @section libkvazaar Kvazaar H.265/HEVC encoder. Requires the presence of the libkvazaar headers and library during configuration. You need to explicitly configure the build with @option{--enable-libkvazaar}. @subsection Options @table @option @item b Set target video bitrate in bit/s and enable rate control. @item kvazaar-params Set kvazaar parameters as a list of @var{name}=@var{value} pairs separated by commas (,). See kvazaar documentation for a list of options. @end table @section libopenh264 Cisco libopenh264 H.264/MPEG-4 AVC encoder wrapper. This encoder requires the presence of the libopenh264 headers and library during configuration. You need to explicitly configure the build with @code{--enable-libopenh264}. The library is detected using @command{pkg-config}. For more information about the library see @url{http://www.openh264.org}. @subsection Options The following FFmpeg global options affect the configurations of the libopenh264 encoder. @table @option @item b Set the bitrate (as a number of bits per second). @item g Set the GOP size. @item maxrate Set the max bitrate (as a number of bits per second). @item flags +global_header Set global header in the bitstream. @item slices Set the number of slices, used in parallelized encoding. Default value is 0. This is only used when @option{slice_mode} is set to @samp{fixed}. @item slice_mode Set slice mode. Can assume one of the following possible values: @table @samp @item fixed a fixed number of slices @item rowmb one slice per row of macroblocks @item auto automatic number of slices according to number of threads @item dyn dynamic slicing @end table Default value is @samp{auto}. @item loopfilter Enable loop filter, if set to 1 (automatically enabled). To disable set a value of 0. @item profile Set profile restrictions. If set to the value of @samp{main} enable CABAC (set the @code{SEncParamExt.iEntropyCodingModeFlag} flag to 1). @item max_nal_size Set maximum NAL size in bytes. @item allow_skip_frames Allow skipping frames to hit the target bitrate if set to 1. @end table @section libtheora libtheora Theora encoder wrapper. Requires the presence of the libtheora headers and library during configuration. You need to explicitly configure the build with @code{--enable-libtheora}. For more information about the libtheora project see @url{http://www.theora.org/}. @subsection Options The following global options are mapped to internal libtheora options which affect the quality and the bitrate of the encoded stream. @table @option @item b Set the video bitrate in bit/s for CBR (Constant Bit Rate) mode. In case VBR (Variable Bit Rate) mode is enabled this option is ignored. @item flags Used to enable constant quality mode (VBR) encoding through the @option{qscale} flag, and to enable the @code{pass1} and @code{pass2} modes. @item g Set the GOP size. @item global_quality Set the global quality as an integer in lambda units. Only relevant when VBR mode is enabled with @code{flags +qscale}. The value is converted to QP units by dividing it by @code{FF_QP2LAMBDA}, clipped in the [0 - 10] range, and then multiplied by 6.3 to get a value in the native libtheora range [0-63]. A higher value corresponds to a higher quality. @item q Enable VBR mode when set to a non-negative value, and set constant quality value as a double floating point value in QP units. The value is clipped in the [0-10] range, and then multiplied by 6.3 to get a value in the native libtheora range [0-63]. This option is valid only using the @command{ffmpeg} command-line tool. For library interface users, use @option{global_quality}. @end table @subsection Examples @itemize @item Set maximum constant quality (VBR) encoding with @command{ffmpeg}: @example ffmpeg -i INPUT -codec:v libtheora -q:v 10 OUTPUT.ogg @end example @item Use @command{ffmpeg} to convert a CBR 1000 kbps Theora video stream: @example ffmpeg -i INPUT -codec:v libtheora -b:v 1000k OUTPUT.ogg @end example @end itemize @section libvpx VP8/VP9 format supported through libvpx. Requires the presence of the libvpx headers and library during configuration. You need to explicitly configure the build with @code{--enable-libvpx}. @subsection Options The following options are supported by the libvpx wrapper. The @command{vpxenc}-equivalent options or values are listed in parentheses for easy migration. To reduce the duplication of documentation, only the private options and some others requiring special attention are documented here. For the documentation of the undocumented generic options, see @ref{codec-options,,the Codec Options chapter}. To get more documentation of the libvpx options, invoke the command @command{ffmpeg -h encoder=libvpx}, @command{ffmpeg -h encoder=libvpx-vp9} or @command{vpxenc --help}. Further information is available in the libvpx API documentation. @table @option @item b (@emph{target-bitrate}) Set bitrate in bits/s. Note that FFmpeg's @option{b} option is expressed in bits/s, while @command{vpxenc}'s @option{target-bitrate} is in kilobits/s. @item g (@emph{kf-max-dist}) @item keyint_min (@emph{kf-min-dist}) @item qmin (@emph{min-q}) @item qmax (@emph{max-q}) @item bufsize (@emph{buf-sz}, @emph{buf-optimal-sz}) Set ratecontrol buffer size (in bits). Note @command{vpxenc}'s options are specified in milliseconds, the libvpx wrapper converts this value as follows: @code{buf-sz = bufsize * 1000 / bitrate}, @code{buf-optimal-sz = bufsize * 1000 / bitrate * 5 / 6}. @item rc_init_occupancy (@emph{buf-initial-sz}) Set number of bits which should be loaded into the rc buffer before decoding starts. Note @command{vpxenc}'s option is specified in milliseconds, the libvpx wrapper converts this value as follows: @code{rc_init_occupancy * 1000 / bitrate}. @item undershoot-pct Set datarate undershoot (min) percentage of the target bitrate. @item overshoot-pct Set datarate overshoot (max) percentage of the target bitrate. @item skip_threshold (@emph{drop-frame}) @item qcomp (@emph{bias-pct}) @item maxrate (@emph{maxsection-pct}) Set GOP max bitrate in bits/s. Note @command{vpxenc}'s option is specified as a percentage of the target bitrate, the libvpx wrapper converts this value as follows: @code{(maxrate * 100 / bitrate)}. @item minrate (@emph{minsection-pct}) Set GOP min bitrate in bits/s. Note @command{vpxenc}'s option is specified as a percentage of the target bitrate, the libvpx wrapper converts this value as follows: @code{(minrate * 100 / bitrate)}. @item minrate, maxrate, b @emph{end-usage=cbr} @code{(minrate == maxrate == bitrate)}. @item crf (@emph{end-usage=cq}, @emph{cq-level}) @item tune (@emph{tune}) @table @samp @item psnr (@emph{psnr}) @item ssim (@emph{ssim}) @end table @item quality, deadline (@emph{deadline}) @table @samp @item best Use best quality deadline. Poorly named and quite slow, this option should be avoided as it may give worse quality output than good. @item good Use good quality deadline. This is a good trade-off between speed and quality when used with the @option{cpu-used} option. @item realtime Use realtime quality deadline. @end table @item speed, cpu-used (@emph{cpu-used}) Set quality/speed ratio modifier. Higher values speed up the encode at the cost of quality. @item nr (@emph{noise-sensitivity}) @item static-thresh Set a change threshold on blocks below which they will be skipped by the encoder. @item slices (@emph{token-parts}) Note that FFmpeg's @option{slices} option gives the total number of partitions, while @command{vpxenc}'s @option{token-parts} is given as @code{log2(partitions)}. @item max-intra-rate Set maximum I-frame bitrate as a percentage of the target bitrate. A value of 0 means unlimited. @item force_key_frames @code{VPX_EFLAG_FORCE_KF} @item Alternate reference frame related @table @option @item auto-alt-ref Enable use of alternate reference frames (2-pass only). Values greater than 1 enable multi-layer alternate reference frames (VP9 only). @item arnr-maxframes Set altref noise reduction max frame count. @item arnr-type Set altref noise reduction filter type: backward, forward, centered. @item arnr-strength Set altref noise reduction filter strength. @item rc-lookahead, lag-in-frames (@emph{lag-in-frames}) Set number of frames to look ahead for frametype and ratecontrol. @end table @item error-resilient Enable error resiliency features. @item sharpness @var{integer} Increase sharpness at the expense of lower PSNR. The valid range is [0, 7]. @item ts-parameters Sets the temporal scalability configuration using a :-separated list of key=value pairs. For example, to specify temporal scalability parameters with @code{ffmpeg}: @example ffmpeg -i INPUT -c:v libvpx -ts-parameters ts_number_layers=3:\ ts_target_bitrate=250,500,1000:ts_rate_decimator=4,2,1:\ ts_periodicity=4:ts_layer_id=0,2,1,2:ts_layering_mode=3 OUTPUT @end example Below is a brief explanation of each of the parameters, please refer to @code{struct vpx_codec_enc_cfg} in @code{vpx/vpx_encoder.h} for more details. @table @option @item ts_number_layers Number of temporal coding layers. @item ts_target_bitrate Target bitrate for each temporal layer (in kbps). (bitrate should be inclusive of the lower temporal layer). @item ts_rate_decimator Frame rate decimation factor for each temporal layer. @item ts_periodicity Length of the sequence defining frame temporal layer membership. @item ts_layer_id Template defining the membership of frames to temporal layers. @item ts_layering_mode (optional) Selecting the temporal structure from a set of pre-defined temporal layering modes. Currently supports the following options. @table @option @item 0 No temporal layering flags are provided internally, relies on flags being passed in using @code{metadata} field in @code{AVFrame} with following keys. @table @option @item vp8-flags Sets the flags passed into the encoder to indicate the referencing scheme for the current frame. Refer to function @code{vpx_codec_encode} in @code{vpx/vpx_encoder.h} for more details. @item temporal_id Explicitly sets the temporal id of the current frame to encode. @end table @item 2 Two temporal layers. 0-1... @item 3 Three temporal layers. 0-2-1-2...; with single reference frame. @item 4 Same as option "3", except there is a dependency between the two temporal layer 2 frames within the temporal period. @end table @end table @item VP9-specific options @table @option @item lossless Enable lossless mode. @item tile-columns Set number of tile columns to use. Note this is given as @code{log2(tile_columns)}. For example, 8 tile columns would be requested by setting the @option{tile-columns} option to 3. @item tile-rows Set number of tile rows to use. Note this is given as @code{log2(tile_rows)}. For example, 4 tile rows would be requested by setting the @option{tile-rows} option to 2. @item frame-parallel Enable frame parallel decodability features. @item aq-mode Set adaptive quantization mode (0: off (default), 1: variance 2: complexity, 3: cyclic refresh, 4: equator360). @item colorspace @emph{color-space} Set input color space. The VP9 bitstream supports signaling the following colorspaces: @table @option @item @samp{rgb} @emph{sRGB} @item @samp{bt709} @emph{bt709} @item @samp{unspecified} @emph{unknown} @item @samp{bt470bg} @emph{bt601} @item @samp{smpte170m} @emph{smpte170} @item @samp{smpte240m} @emph{smpte240} @item @samp{bt2020_ncl} @emph{bt2020} @end table @item row-mt @var{boolean} Enable row based multi-threading. @item tune-content Set content type: default (0), screen (1), film (2). @item corpus-complexity Corpus VBR mode is a variant of standard VBR where the complexity distribution midpoint is passed in rather than calculated for a specific clip or chunk. The valid range is [0, 10000]. 0 (default) uses standard VBR. @item enable-tpl @var{boolean} Enable temporal dependency model. @end table @end table For more information about libvpx see: @url{http://www.webmproject.org/} @section libwebp libwebp WebP Image encoder wrapper libwebp is Google's official encoder for WebP images. It can encode in either lossy or lossless mode. Lossy images are essentially a wrapper around a VP8 frame. Lossless images are a separate codec developed by Google. @subsection Pixel Format Currently, libwebp only supports YUV420 for lossy and RGB for lossless due to limitations of the format and libwebp. Alpha is supported for either mode. Because of API limitations, if RGB is passed in when encoding lossy or YUV is passed in for encoding lossless, the pixel format will automatically be converted using functions from libwebp. This is not ideal and is done only for convenience. @subsection Options @table @option @item -lossless @var{boolean} Enables/Disables use of lossless mode. Default is 0. @item -compression_level @var{integer} For lossy, this is a quality/speed tradeoff. Higher values give better quality for a given size at the cost of increased encoding time. For lossless, this is a size/speed tradeoff. Higher values give smaller size at the cost of increased encoding time. More specifically, it controls the number of extra algorithms and compression tools used, and varies the combination of these tools. This maps to the @var{method} option in libwebp. The valid range is 0 to 6. Default is 4. @item -qscale @var{float} For lossy encoding, this controls image quality, 0 to 100. For lossless encoding, this controls the effort and time spent at compressing more. The default value is 75. Note that for usage via libavcodec, this option is called @var{global_quality} and must be multiplied by @var{FF_QP2LAMBDA}. @item -preset @var{type} Configuration preset. This does some automatic settings based on the general type of the image. @table @option @item none Do not use a preset. @item default Use the encoder default. @item picture Digital picture, like portrait, inner shot @item photo Outdoor photograph, with natural lighting @item drawing Hand or line drawing, with high-contrast details @item icon Small-sized colorful images @item text Text-like @end table @end table @section libx264, libx264rgb x264 H.264/MPEG-4 AVC encoder wrapper. This encoder requires the presence of the libx264 headers and library during configuration. You need to explicitly configure the build with @code{--enable-libx264}. libx264 supports an impressive number of features, including 8x8 and 4x4 adaptive spatial transform, adaptive B-frame placement, CAVLC/CABAC entropy coding, interlacing (MBAFF), lossless mode, psy optimizations for detail retention (adaptive quantization, psy-RD, psy-trellis). Many libx264 encoder options are mapped to FFmpeg global codec options, while unique encoder options are provided through private options. Additionally the @option{x264opts} and @option{x264-params} private options allows one to pass a list of key=value tuples as accepted by the libx264 @code{x264_param_parse} function. The x264 project website is at @url{http://www.videolan.org/developers/x264.html}. The libx264rgb encoder is the same as libx264, except it accepts packed RGB pixel formats as input instead of YUV. @subsection Supported Pixel Formats x264 supports 8- to 10-bit color spaces. The exact bit depth is controlled at x264's configure time. FFmpeg only supports one bit depth in one particular build. In other words, it is not possible to build one FFmpeg with multiple versions of x264 with different bit depths. @subsection Options The following options are supported by the libx264 wrapper. The @command{x264}-equivalent options or values are listed in parentheses for easy migration. To reduce the duplication of documentation, only the private options and some others requiring special attention are documented here. For the documentation of the undocumented generic options, see @ref{codec-options,,the Codec Options chapter}. To get a more accurate and extensive documentation of the libx264 options, invoke the command @command{x264 --fullhelp} or consult the libx264 documentation. @table @option @item b (@emph{bitrate}) Set bitrate in bits/s. Note that FFmpeg's @option{b} option is expressed in bits/s, while @command{x264}'s @option{bitrate} is in kilobits/s. @item bf (@emph{bframes}) @item g (@emph{keyint}) @item qmin (@emph{qpmin}) Minimum quantizer scale. @item qmax (@emph{qpmax}) Maximum quantizer scale. @item qdiff (@emph{qpstep}) Maximum difference between quantizer scales. @item qblur (@emph{qblur}) Quantizer curve blur @item qcomp (@emph{qcomp}) Quantizer curve compression factor @item refs (@emph{ref}) Number of reference frames each P-frame can use. The range is from @var{0-16}. @item sc_threshold (@emph{scenecut}) Sets the threshold for the scene change detection. @item trellis (@emph{trellis}) Performs Trellis quantization to increase efficiency. Enabled by default. @item nr (@emph{nr}) @item me_range (@emph{merange}) Maximum range of the motion search in pixels. @item me_method (@emph{me}) Set motion estimation method. Possible values in the decreasing order of speed: @table @samp @item dia (@emph{dia}) @item epzs (@emph{dia}) Diamond search with radius 1 (fastest). @samp{epzs} is an alias for @samp{dia}. @item hex (@emph{hex}) Hexagonal search with radius 2. @item umh (@emph{umh}) Uneven multi-hexagon search. @item esa (@emph{esa}) Exhaustive search. @item tesa (@emph{tesa}) Hadamard exhaustive search (slowest). @end table @item forced-idr Normally, when forcing a I-frame type, the encoder can select any type of I-frame. This option forces it to choose an IDR-frame. @item subq (@emph{subme}) Sub-pixel motion estimation method. @item b_strategy (@emph{b-adapt}) Adaptive B-frame placement decision algorithm. Use only on first-pass. @item keyint_min (@emph{min-keyint}) Minimum GOP size. @item coder Set entropy encoder. Possible values: @table @samp @item ac Enable CABAC. @item vlc Enable CAVLC and disable CABAC. It generates the same effect as @command{x264}'s @option{--no-cabac} option. @end table @item cmp Set full pixel motion estimation comparison algorithm. Possible values: @table @samp @item chroma Enable chroma in motion estimation. @item sad Ignore chroma in motion estimation. It generates the same effect as @command{x264}'s @option{--no-chroma-me} option. @end table @item threads (@emph{threads}) Number of encoding threads. @item thread_type Set multithreading technique. Possible values: @table @samp @item slice Slice-based multithreading. It generates the same effect as @command{x264}'s @option{--sliced-threads} option. @item frame Frame-based multithreading. @end table @item flags Set encoding flags. It can be used to disable closed GOP and enable open GOP by setting it to @code{-cgop}. The result is similar to the behavior of @command{x264}'s @option{--open-gop} option. @item rc_init_occupancy (@emph{vbv-init}) @item preset (@emph{preset}) Set the encoding preset. @item tune (@emph{tune}) Set tuning of the encoding params. @item profile (@emph{profile}) Set profile restrictions. @item fastfirstpass Enable fast settings when encoding first pass, when set to 1. When set to 0, it has the same effect of @command{x264}'s @option{--slow-firstpass} option. @item crf (@emph{crf}) Set the quality for constant quality mode. @item crf_max (@emph{crf-max}) In CRF mode, prevents VBV from lowering quality beyond this point. @item qp (@emph{qp}) Set constant quantization rate control method parameter. @item aq-mode (@emph{aq-mode}) Set AQ method. Possible values: @table @samp @item none (@emph{0}) Disabled. @item variance (@emph{1}) Variance AQ (complexity mask). @item autovariance (@emph{2}) Auto-variance AQ (experimental). @end table @item aq-strength (@emph{aq-strength}) Set AQ strength, reduce blocking and blurring in flat and textured areas. @item psy Use psychovisual optimizations when set to 1. When set to 0, it has the same effect as @command{x264}'s @option{--no-psy} option. @item psy-rd (@emph{psy-rd}) Set strength of psychovisual optimization, in @var{psy-rd}:@var{psy-trellis} format. @item rc-lookahead (@emph{rc-lookahead}) Set number of frames to look ahead for frametype and ratecontrol. @item weightb Enable weighted prediction for B-frames when set to 1. When set to 0, it has the same effect as @command{x264}'s @option{--no-weightb} option. @item weightp (@emph{weightp}) Set weighted prediction method for P-frames. Possible values: @table @samp @item none (@emph{0}) Disabled @item simple (@emph{1}) Enable only weighted refs @item smart (@emph{2}) Enable both weighted refs and duplicates @end table @item ssim (@emph{ssim}) Enable calculation and printing SSIM stats after the encoding. @item intra-refresh (@emph{intra-refresh}) Enable the use of Periodic Intra Refresh instead of IDR frames when set to 1. @item avcintra-class (@emph{class}) Configure the encoder to generate AVC-Intra. Valid values are 50,100 and 200 @item bluray-compat (@emph{bluray-compat}) Configure the encoder to be compatible with the bluray standard. It is a shorthand for setting "bluray-compat=1 force-cfr=1". @item b-bias (@emph{b-bias}) Set the influence on how often B-frames are used. @item b-pyramid (@emph{b-pyramid}) Set method for keeping of some B-frames as references. Possible values: @table @samp @item none (@emph{none}) Disabled. @item strict (@emph{strict}) Strictly hierarchical pyramid. @item normal (@emph{normal}) Non-strict (not Blu-ray compatible). @end table @item mixed-refs Enable the use of one reference per partition, as opposed to one reference per macroblock when set to 1. When set to 0, it has the same effect as @command{x264}'s @option{--no-mixed-refs} option. @item 8x8dct Enable adaptive spatial transform (high profile 8x8 transform) when set to 1. When set to 0, it has the same effect as @command{x264}'s @option{--no-8x8dct} option. @item fast-pskip Enable early SKIP detection on P-frames when set to 1. When set to 0, it has the same effect as @command{x264}'s @option{--no-fast-pskip} option. @item aud (@emph{aud}) Enable use of access unit delimiters when set to 1. @item mbtree Enable use macroblock tree ratecontrol when set to 1. When set to 0, it has the same effect as @command{x264}'s @option{--no-mbtree} option. @item deblock (@emph{deblock}) Set loop filter parameters, in @var{alpha}:@var{beta} form. @item cplxblur (@emph{cplxblur}) Set fluctuations reduction in QP (before curve compression). @item partitions (@emph{partitions}) Set partitions to consider as a comma-separated list of. Possible values in the list: @table @samp @item p8x8 8x8 P-frame partition. @item p4x4 4x4 P-frame partition. @item b8x8 4x4 B-frame partition. @item i8x8 8x8 I-frame partition. @item i4x4 4x4 I-frame partition. (Enabling @samp{p4x4} requires @samp{p8x8} to be enabled. Enabling @samp{i8x8} requires adaptive spatial transform (@option{8x8dct} option) to be enabled.) @item none (@emph{none}) Do not consider any partitions. @item all (@emph{all}) Consider every partition. @end table @item direct-pred (@emph{direct}) Set direct MV prediction mode. Possible values: @table @samp @item none (@emph{none}) Disable MV prediction. @item spatial (@emph{spatial}) Enable spatial predicting. @item temporal (@emph{temporal}) Enable temporal predicting. @item auto (@emph{auto}) Automatically decided. @end table @item slice-max-size (@emph{slice-max-size}) Set the limit of the size of each slice in bytes. If not specified but RTP payload size (@option{ps}) is specified, that is used. @item stats (@emph{stats}) Set the file name for multi-pass stats. @item nal-hrd (@emph{nal-hrd}) Set signal HRD information (requires @option{vbv-bufsize} to be set). Possible values: @table @samp @item none (@emph{none}) Disable HRD information signaling. @item vbr (@emph{vbr}) Variable bit rate. @item cbr (@emph{cbr}) Constant bit rate (not allowed in MP4 container). @end table @item x264opts (N.A.) Set any x264 option, see @command{x264 --fullhelp} for a list. Argument is a list of @var{key}=@var{value} couples separated by ":". In @var{filter} and @var{psy-rd} options that use ":" as a separator themselves, use "," instead. They accept it as well since long ago but this is kept undocumented for some reason. For example to specify libx264 encoding options with @command{ffmpeg}: @example ffmpeg -i foo.mpg -c:v libx264 -x264opts keyint=123:min-keyint=20 -an out.mkv @end example @item a53cc @var{boolean} Import closed captions (which must be ATSC compatible format) into output. Only the mpeg2 and h264 decoders provide these. Default is 1 (on). @item x264-params (N.A.) Override the x264 configuration using a :-separated list of key=value parameters. This option is functionally the same as the @option{x264opts}, but is duplicated for compatibility with the Libav fork. For example to specify libx264 encoding options with @command{ffmpeg}: @example ffmpeg -i INPUT -c:v libx264 -x264-params level=30:bframes=0:weightp=0:\ cabac=0:ref=1:vbv-maxrate=768:vbv-bufsize=2000:analyse=all:me=umh:\ no-fast-pskip=1:subq=6:8x8dct=0:trellis=0 OUTPUT @end example @end table Encoding ffpresets for common usages are provided so they can be used with the general presets system (e.g. passing the @option{pre} option). @section libx265 x265 H.265/HEVC encoder wrapper. This encoder requires the presence of the libx265 headers and library during configuration. You need to explicitly configure the build with @option{--enable-libx265}. @subsection Options @table @option @item b Sets target video bitrate. @item bf @item g Set the GOP size. @item keyint_min Minimum GOP size. @item refs Number of reference frames each P-frame can use. The range is from @var{1-16}. @item preset Set the x265 preset. @item tune Set the x265 tune parameter. @item profile Set profile restrictions. @item crf Set the quality for constant quality mode. @item qp Set constant quantization rate control method parameter. @item qmin Minimum quantizer scale. @item qmax Maximum quantizer scale. @item qdiff Maximum difference between quantizer scales. @item qblur Quantizer curve blur @item qcomp Quantizer curve compression factor @item i_qfactor @item b_qfactor @item forced-idr Normally, when forcing a I-frame type, the encoder can select any type of I-frame. This option forces it to choose an IDR-frame. @item x265-params Set x265 options using a list of @var{key}=@var{value} couples separated by ":". See @command{x265 --help} for a list of options. For example to specify libx265 encoding options with @option{-x265-params}: @example ffmpeg -i input -c:v libx265 -x265-params crf=26:psy-rd=1 output.mp4 @end example @end table @section libxavs2 xavs2 AVS2-P2/IEEE1857.4 encoder wrapper. This encoder requires the presence of the libxavs2 headers and library during configuration. You need to explicitly configure the build with @option{--enable-libxavs2}. The following standard libavcodec options are used: @itemize @item @option{b} / @option{bit_rate} @item @option{g} / @option{gop_size} @item @option{bf} / @option{max_b_frames} @end itemize The encoder also has its own specific options: @subsection Options @table @option @item lcu_row_threads Set the number of parallel threads for rows from 1 to 8 (default 5). @item initial_qp Set the xavs2 quantization parameter from 1 to 63 (default 34). This is used to set the initial qp for the first frame. @item qp Set the xavs2 quantization parameter from 1 to 63 (default 34). This is used to set the qp value under constant-QP mode. @item max_qp Set the max qp for rate control from 1 to 63 (default 55). @item min_qp Set the min qp for rate control from 1 to 63 (default 20). @item speed_level Set the Speed level from 0 to 9 (default 0). Higher is better but slower. @item log_level Set the log level from -1 to 3 (default 0). -1: none, 0: error, 1: warning, 2: info, 3: debug. @item xavs2-params Set xavs2 options using a list of @var{key}=@var{value} couples separated by ":". For example to specify libxavs2 encoding options with @option{-xavs2-params}: @example ffmpeg -i input -c:v libxavs2 -xavs2-params RdoqLevel=0 output.avs2 @end example @end table @section libxvid Xvid MPEG-4 Part 2 encoder wrapper. This encoder requires the presence of the libxvidcore headers and library during configuration. You need to explicitly configure the build with @code{--enable-libxvid --enable-gpl}. The native @code{mpeg4} encoder supports the MPEG-4 Part 2 format, so users can encode to this format without this library. @subsection Options The following options are supported by the libxvid wrapper. Some of the following options are listed but are not documented, and correspond to shared codec options. See @ref{codec-options,,the Codec Options chapter} for their documentation. The other shared options which are not listed have no effect for the libxvid encoder. @table @option @item b @item g @item qmin @item qmax @item mpeg_quant @item threads @item bf @item b_qfactor @item b_qoffset @item flags Set specific encoding flags. Possible values: @table @samp @item mv4 Use four motion vector by macroblock. @item aic Enable high quality AC prediction. @item gray Only encode grayscale. @item gmc Enable the use of global motion compensation (GMC). @item qpel Enable quarter-pixel motion compensation. @item cgop Enable closed GOP. @item global_header Place global headers in extradata instead of every keyframe. @end table @item trellis @item me_method Set motion estimation method. Possible values in decreasing order of speed and increasing order of quality: @table @samp @item zero Use no motion estimation (default). @item phods @item x1 @item log Enable advanced diamond zonal search for 16x16 blocks and half-pixel refinement for 16x16 blocks. @samp{x1} and @samp{log} are aliases for @samp{phods}. @item epzs Enable all of the things described above, plus advanced diamond zonal search for 8x8 blocks, half-pixel refinement for 8x8 blocks, and motion estimation on chroma planes. @item full Enable all of the things described above, plus extended 16x16 and 8x8 blocks search. @end table @item mbd Set macroblock decision algorithm. Possible values in the increasing order of quality: @table @samp @item simple Use macroblock comparing function algorithm (default). @item bits Enable rate distortion-based half pixel and quarter pixel refinement for 16x16 blocks. @item rd Enable all of the things described above, plus rate distortion-based half pixel and quarter pixel refinement for 8x8 blocks, and rate distortion-based search using square pattern. @end table @item lumi_aq Enable lumi masking adaptive quantization when set to 1. Default is 0 (disabled). @item variance_aq Enable variance adaptive quantization when set to 1. Default is 0 (disabled). When combined with @option{lumi_aq}, the resulting quality will not be better than any of the two specified individually. In other words, the resulting quality will be the worse one of the two effects. @item ssim Set structural similarity (SSIM) displaying method. Possible values: @table @samp @item off Disable displaying of SSIM information. @item avg Output average SSIM at the end of encoding to stdout. The format of showing the average SSIM is: @example Average SSIM: %f @end example For users who are not familiar with C, %f means a float number, or a decimal (e.g. 0.939232). @item frame Output both per-frame SSIM data during encoding and average SSIM at the end of encoding to stdout. The format of per-frame information is: @example SSIM: avg: %1.3f min: %1.3f max: %1.3f @end example For users who are not familiar with C, %1.3f means a float number rounded to 3 digits after the dot (e.g. 0.932). @end table @item ssim_acc Set SSIM accuracy. Valid options are integers within the range of 0-4, while 0 gives the most accurate result and 4 computes the fastest. @end table @section MediaFoundation This provides wrappers to encoders (both audio and video) in the MediaFoundation framework. It can access both SW and HW encoders. Video encoders can take input in either of nv12 or yuv420p form (some encoders support both, some support only either - in practice, nv12 is the safer choice, especially among HW encoders). @section mpeg2 MPEG-2 video encoder. @subsection Options @table @option @item profile Select the mpeg2 profile to encode: @table @samp @item 422 @item high @item ss Spatially Scalable @item snr SNR Scalable @item main @item simple @end table @item level Select the mpeg2 level to encode: @table @samp @item high @item high1440 @item main @item low @end table @item seq_disp_ext @var{integer} Specifies if the encoder should write a sequence_display_extension to the output. @table @option @item -1 @itemx auto Decide automatically to write it or not (this is the default) by checking if the data to be written is different from the default or unspecified values. @item 0 @itemx never Never write it. @item 1 @itemx always Always write it. @end table @item video_format @var{integer} Specifies the video_format written into the sequence display extension indicating the source of the video pictures. The default is @samp{unspecified}, can be @samp{component}, @samp{pal}, @samp{ntsc}, @samp{secam} or @samp{mac}. For maximum compatibility, use @samp{component}. @item a53cc @var{boolean} Import closed captions (which must be ATSC compatible format) into output. Default is 1 (on). @end table @section png PNG image encoder. @subsection Private options @table @option @item dpi @var{integer} Set physical density of pixels, in dots per inch, unset by default @item dpm @var{integer} Set physical density of pixels, in dots per meter, unset by default @end table @section ProRes Apple ProRes encoder. FFmpeg contains 2 ProRes encoders, the prores-aw and prores-ks encoder. The used encoder can be chosen with the @code{-vcodec} option. @subsection Private Options for prores-ks @table @option @item profile @var{integer} Select the ProRes profile to encode @table @samp @item proxy @item lt @item standard @item hq @item 4444 @item 4444xq @end table @item quant_mat @var{integer} Select quantization matrix. @table @samp @item auto @item default @item proxy @item lt @item standard @item hq @end table If set to @var{auto}, the matrix matching the profile will be picked. If not set, the matrix providing the highest quality, @var{default}, will be picked. @item bits_per_mb @var{integer} How many bits to allot for coding one macroblock. Different profiles use between 200 and 2400 bits per macroblock, the maximum is 8000. @item mbs_per_slice @var{integer} Number of macroblocks in each slice (1-8); the default value (8) should be good in almost all situations. @item vendor @var{string} Override the 4-byte vendor ID. A custom vendor ID like @var{apl0} would claim the stream was produced by the Apple encoder. @item alpha_bits @var{integer} Specify number of bits for alpha component. Possible values are @var{0}, @var{8} and @var{16}. Use @var{0} to disable alpha plane coding. @end table @subsection Speed considerations In the default mode of operation the encoder has to honor frame constraints (i.e. not produce frames with size bigger than requested) while still making output picture as good as possible. A frame containing a lot of small details is harder to compress and the encoder would spend more time searching for appropriate quantizers for each slice. Setting a higher @option{bits_per_mb} limit will improve the speed. For the fastest encoding speed set the @option{qscale} parameter (4 is the recommended value) and do not set a size constraint. @section QSV encoders The family of Intel QuickSync Video encoders (MPEG-2, H.264, HEVC, JPEG/MJPEG and VP9) The ratecontrol method is selected as follows: @itemize @bullet @item When @option{global_quality} is specified, a quality-based mode is used. Specifically this means either @itemize @minus @item @var{CQP} - constant quantizer scale, when the @option{qscale} codec flag is also set (the @option{-qscale} ffmpeg option). @item @var{LA_ICQ} - intelligent constant quality with lookahead, when the @option{look_ahead} option is also set. @item @var{ICQ} -- intelligent constant quality otherwise. @end itemize @item Otherwise, a bitrate-based mode is used. For all of those, you should specify at least the desired average bitrate with the @option{b} option. @itemize @minus @item @var{LA} - VBR with lookahead, when the @option{look_ahead} option is specified. @item @var{VCM} - video conferencing mode, when the @option{vcm} option is set. @item @var{CBR} - constant bitrate, when @option{maxrate} is specified and equal to the average bitrate. @item @var{VBR} - variable bitrate, when @option{maxrate} is specified, but is higher than the average bitrate. @item @var{AVBR} - average VBR mode, when @option{maxrate} is not specified. This mode is further configured by the @option{avbr_accuracy} and @option{avbr_convergence} options. @end itemize @end itemize Note that depending on your system, a different mode than the one you specified may be selected by the encoder. Set the verbosity level to @var{verbose} or higher to see the actual settings used by the QSV runtime. Additional libavcodec global options are mapped to MSDK options as follows: @itemize @item @option{g/gop_size} -> @option{GopPicSize} @item @option{bf/max_b_frames}+1 -> @option{GopRefDist} @item @option{rc_init_occupancy/rc_initial_buffer_occupancy} -> @option{InitialDelayInKB} @item @option{slices} -> @option{NumSlice} @item @option{refs} -> @option{NumRefFrame} @item @option{b_strategy/b_frame_strategy} -> @option{BRefType} @item @option{cgop/CLOSED_GOP} codec flag -> @option{GopOptFlag} @item For the @var{CQP} mode, the @option{i_qfactor/i_qoffset} and @option{b_qfactor/b_qoffset} set the difference between @var{QPP} and @var{QPI}, and @var{QPP} and @var{QPB} respectively. @item Setting the @option{coder} option to the value @var{vlc} will make the H.264 encoder use CAVLC instead of CABAC. @end itemize @section snow @subsection Options @table @option @item iterative_dia_size dia size for the iterative motion estimation @end table @section VAAPI encoders Wrappers for hardware encoders accessible via VAAPI. These encoders only accept input in VAAPI hardware surfaces. If you have input in software frames, use the @option{hwupload} filter to upload them to the GPU. The following standard libavcodec options are used: @itemize @item @option{g} / @option{gop_size} @item @option{bf} / @option{max_b_frames} @item @option{profile} If not set, this will be determined automatically from the format of the input frames and the profiles supported by the driver. @item @option{level} @item @option{b} / @option{bit_rate} @item @option{maxrate} / @option{rc_max_rate} @item @option{bufsize} / @option{rc_buffer_size} @item @option{rc_init_occupancy} / @option{rc_initial_buffer_occupancy} @item @option{compression_level} Speed / quality tradeoff: higher values are faster / worse quality. @item @option{q} / @option{global_quality} Size / quality tradeoff: higher values are smaller / worse quality. @item @option{qmin} @item @option{qmax} @item @option{i_qfactor} / @option{i_quant_factor} @item @option{i_qoffset} / @option{i_quant_offset} @item @option{b_qfactor} / @option{b_quant_factor} @item @option{b_qoffset} / @option{b_quant_offset} @item @option{slices} @end itemize All encoders support the following options: @table @option @item low_power Some drivers/platforms offer a second encoder for some codecs intended to use less power than the default encoder; setting this option will attempt to use that encoder. Note that it may support a reduced feature set, so some other options may not be available in this mode. @item idr_interval Set the number of normal intra frames between full-refresh (IDR) frames in open-GOP mode. The intra frames are still IRAPs, but will not include global headers and may have non-decodable leading pictures. @item b_depth Set the B-frame reference depth. When set to one (the default), all B-frames will refer only to P- or I-frames. When set to greater values multiple layers of B-frames will be present, frames in each layer only referring to frames in higher layers. @item rc_mode Set the rate control mode to use. A given driver may only support a subset of modes. Possible modes: @table @option @item auto Choose the mode automatically based on driver support and the other options. This is the default. @item CQP Constant-quality. @item CBR Constant-bitrate. @item VBR Variable-bitrate. @item ICQ Intelligent constant-quality. @item QVBR Quality-defined variable-bitrate. @item AVBR Average variable bitrate. @end table @end table Each encoder also has its own specific options: @table @option @item h264_vaapi @option{profile} sets the value of @emph{profile_idc} and the @emph{constraint_set*_flag}s. @option{level} sets the value of @emph{level_idc}. @table @option @item coder Set entropy encoder (default is @emph{cabac}). Possible values: @table @samp @item ac @item cabac Use CABAC. @item vlc @item cavlc Use CAVLC. @end table @item aud Include access unit delimiters in the stream (not included by default). @item sei Set SEI message types to include. Some combination of the following values: @table @samp @item identifier Include a @emph{user_data_unregistered} message containing information about the encoder. @item timing Include picture timing parameters (@emph{buffering_period} and @emph{pic_timing} messages). @item recovery_point Include recovery points where appropriate (@emph{recovery_point} messages). @end table @end table @item hevc_vaapi @option{profile} and @option{level} set the values of @emph{general_profile_idc} and @emph{general_level_idc} respectively. @table @option @item aud Include access unit delimiters in the stream (not included by default). @item tier Set @emph{general_tier_flag}. This may affect the level chosen for the stream if it is not explicitly specified. @item sei Set SEI message types to include. Some combination of the following values: @table @samp @item hdr Include HDR metadata if the input frames have it (@emph{mastering_display_colour_volume} and @emph{content_light_level} messages). @end table @item tiles Set the number of tiles to encode the input video with, as columns x rows. Larger numbers allow greater parallelism in both encoding and decoding, but may decrease coding efficiency. @end table @item mjpeg_vaapi Only baseline DCT encoding is supported. The encoder always uses the standard quantisation and huffman tables - @option{global_quality} scales the standard quantisation table (range 1-100). For YUV, 4:2:0, 4:2:2 and 4:4:4 subsampling modes are supported. RGB is also supported, and will create an RGB JPEG. @table @option @item jfif Include JFIF header in each frame (not included by default). @item huffman Include standard huffman tables (on by default). Turning this off will save a few hundred bytes in each output frame, but may lose compatibility with some JPEG decoders which don't fully handle MJPEG. @end table @item mpeg2_vaapi @option{profile} and @option{level} set the value of @emph{profile_and_level_indication}. @item vp8_vaapi B-frames are not supported. @option{global_quality} sets the @emph{q_idx} used for non-key frames (range 0-127). @table @option @item loop_filter_level @item loop_filter_sharpness Manually set the loop filter parameters. @end table @item vp9_vaapi @option{global_quality} sets the @emph{q_idx} used for P-frames (range 0-255). @table @option @item loop_filter_level @item loop_filter_sharpness Manually set the loop filter parameters. @end table B-frames are supported, but the output stream is always in encode order rather than display order. If B-frames are enabled, it may be necessary to use the @option{vp9_raw_reorder} bitstream filter to modify the output stream to display frames in the correct order. Only normal frames are produced - the @option{vp9_superframe} bitstream filter may be required to produce a stream usable with all decoders. @end table @section vc2 SMPTE VC-2 (previously BBC Dirac Pro). This codec was primarily aimed at professional broadcasting but since it supports yuv420, yuv422 and yuv444 at 8 (limited range or full range), 10 or 12 bits, this makes it suitable for other tasks which require low overhead and low compression (like screen recording). @subsection Options @table @option @item b Sets target video bitrate. Usually that's around 1:6 of the uncompressed video bitrate (e.g. for 1920x1080 50fps yuv422p10 that's around 400Mbps). Higher values (close to the uncompressed bitrate) turn on lossless compression mode. @item field_order Enables field coding when set (e.g. to tt - top field first) for interlaced inputs. Should increase compression with interlaced content as it splits the fields and encodes each separately. @item wavelet_depth Sets the total amount of wavelet transforms to apply, between 1 and 5 (default). Lower values reduce compression and quality. Less capable decoders may not be able to handle values of @option{wavelet_depth} over 3. @item wavelet_type Sets the transform type. Currently only @var{5_3} (LeGall) and @var{9_7} (Deslauriers-Dubuc) are implemented, with 9_7 being the one with better compression and thus is the default. @item slice_width @item slice_height Sets the slice size for each slice. Larger values result in better compression. For compatibility with other more limited decoders use @option{slice_width} of 32 and @option{slice_height} of 8. @item tolerance Sets the undershoot tolerance of the rate control system in percent. This is to prevent an expensive search from being run. @item qm Sets the quantization matrix preset to use by default or when @option{wavelet_depth} is set to 5 @itemize @minus @item @var{default} Uses the default quantization matrix from the specifications, extended with values for the fifth level. This provides a good balance between keeping detail and omitting artifacts. @item @var{flat} Use a completely zeroed out quantization matrix. This increases PSNR but might reduce perception. Use in bogus benchmarks. @item @var{color} Reduces detail but attempts to preserve color at extremely low bitrates. @end itemize @end table @c man end VIDEO ENCODERS @chapter Subtitles Encoders @c man begin SUBTITLES ENCODERS @section dvdsub This codec encodes the bitmap subtitle format that is used in DVDs. Typically they are stored in VOBSUB file pairs (*.idx + *.sub), and they can also be used in Matroska files. @subsection Options @table @option @item palette Specify the global palette used by the bitmaps. The format for this option is a string containing 16 24-bits hexadecimal numbers (without 0x prefix) separated by commas, for example @code{0d00ee, ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1, 7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c, 7c127b}. @item even_rows_fix When set to 1, enable a work-around that makes the number of pixel rows even in all subtitles. This fixes a problem with some players that cut off the bottom row if the number is odd. The work-around just adds a fully transparent row if needed. The overhead is low, typically one byte per subtitle on average. By default, this work-around is disabled. @end table @c man end SUBTITLES ENCODERS