@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 an experimental FFmpeg-native AAC encoder. Currently only the
 low complexity (AAC-LC) profile is supported. To use this encoder, you must set
 @option{strict} option to @samp{experimental} or lower.
 
 As this encoder is experimental, unexpected behavior may exist from time to
 time. For a more stable AAC encoder, see @ref{libvo-aacenc}. However, be warned
 that it has a worse quality reported by some users.
 

 @c todo @ref{libaacplus}
 See also @ref{libfdk-aac-enc,,libfdk_aac} and @ref{libfaac}.

 
 @subsection Options
 
 @table @option
 @item b
 Set bit rate in bits/s. Setting this automatically activates constant bit rate
 (CBR) mode.
 
 @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 stereo_mode
 Set stereo encoding mode. Possible values:
 
 @table @samp
 @item auto
 Automatically selected by the encoder.
 
 @item ms_off
 Disable middle/side encoding. This is the default.
 
 @item ms_force
 Force middle/side encoding.
 @end table
 
 @item aac_coder
 Set AAC encoder coding method. Possible values:
 
 @table @samp
 @item faac
 FAAC-inspired method.
 
 This method is a simplified reimplementation of the method used in FAAC, which
 sets thresholds proportional to the band energies, and then decreases all the
 thresholds with quantizer steps to find the appropriate quantization with
 distortion below threshold band by band.
 
 The quality of this method is comparable to the two loop searching method

 described below, but somewhat a little better and slower.

 
 @item anmr
 Average noise to mask ratio (ANMR) trellis-based solution.
 
 This has a theoretic best quality out of all the coding methods, but at the
 cost of the slowest speed.
 
 @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.
 
 This method produces similar quality with the FAAC method and is the default.
 
 @item fast
 Constant quantizer method.
 
 This method sets a constant quantizer for all bands. This is the fastest of all
 the methods, yet produces the worst quality.
 
 @end table
 
 @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.
 
 @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.
 
 @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
 Chanels 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{libfaac}
 @section libfaac
 
 libfaac AAC (Advanced Audio Coding) encoder wrapper.
 
 Requires the presence of the libfaac headers and library during
 configuration. You need to explicitly configure the build with
 @code{--enable-libfaac --enable-nonfree}.
 
 This encoder is considered to be of higher quality with respect to the
 @ref{aacenc,,the native experimental FFmpeg AAC encoder}.
 
 For more information see the libfaac project at
 @url{http://www.audiocoding.com/faac.html/}.
 
 @subsection Options
 
 The following shared FFmpeg codec options are recognized.
 
 The following options are supported by the libfaac wrapper. The
 @command{faac}-equivalent of the options are listed in parentheses.
 
 @table @option
 @item b (@emph{-b})
 Set bit rate in bits/s for ABR (Average Bit Rate) mode. If the bit rate
 is not explicitly specified, it is automatically set to a suitable
 value depending on the selected profile. @command{faac} bitrate is
 expressed in kilobits/s.
 
 Note that libfaac does not support CBR (Constant Bit Rate) but only
 ABR (Average Bit Rate).
 
 If VBR mode is enabled this option is ignored.
 
 @item ar (@emph{-R})
 Set audio sampling rate (in Hz).
 
 @item ac (@emph{-c})
 Set the number of audio channels.
 
 @item cutoff (@emph{-C})
 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_main
 Main AAC (Main)
 
 @item aac_low
 Low Complexity AAC (LC)
 
 @item aac_ssr
 Scalable Sample Rate (SSR)
 
 @item aac_ltp
 Long Term Prediction (LTP)
 @end table
 
 If not specified it is set to @samp{aac_low}.
 
 @item flags +qscale
 Set constant quality VBR (Variable Bit Rate) mode.
 
 @item global_quality
 Set quality in VBR mode as an integer number of 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},
 and used to set the quality value used by libfaac. A reasonable range
 for the option value in QP units is [10-500], the higher the value the
 higher the quality.
 
 @item q (@emph{-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 sets the quality value used by libfaac. A reasonable range
 for the option value is [10-500], the higher the value the higher the
 quality.
 
 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
 Use @command{ffmpeg} to convert an audio file to ABR 128 kbps AAC in an M4A (MP4)
 container:
 @example
 ffmpeg -i input.wav -codec:a libfaac -b:a 128k -output.m4a
 @end example
 
 @item
 Use @command{ffmpeg} to convert an audio file to VBR AAC, using the
 LTP AAC profile:
 @example
 ffmpeg -i input.wav -c:a libfaac -profile:a aac_ltp -q:a 100 output.m4a
 @end example
 @end itemize
 

 @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 is considered to be of higher quality with respect to
 both @ref{aacenc,,the native experimental FFmpeg AAC encoder} and

 @ref{libfaac}.

 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 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 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
 

 @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
 

 @anchor{libvo-aacenc}

 @section libvo-aacenc
 

 VisualOn AAC encoder.

 
 Requires the presence of the libvo-aacenc headers and library during
 configuration. You need to explicitly configure the build with
 @code{--enable-libvo-aacenc --enable-version3}.
 

 This encoder is considered to be worse than the
 @ref{aacenc,,native experimental FFmpeg AAC encoder}, according to
 multiple sources.
 

 @subsection Options
 
 The VisualOn AAC encoder only support encoding AAC-LC and up to 2

 channels. It is also CBR-only.

 
 @table @option
 
 @item b

 Set bit rate in bits/s.

 
 @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 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 their @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).
 
 @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{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 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
 
 Mapping from FFmpeg to libvpx options with conversion notes in parentheses.
 
 @table @option
 
 @item threads
 g_threads
 
 @item profile
 g_profile
 
 @item vb
 rc_target_bitrate
 
 @item g
 kf_max_dist
 
 @item keyint_min
 kf_min_dist
 
 @item qmin
 rc_min_quantizer
 
 @item qmax
 rc_max_quantizer
 
 @item bufsize, vb
 rc_buf_sz
 @code{(bufsize * 1000 / vb)}
 
 rc_buf_optimal_sz
 @code{(bufsize * 1000 / vb * 5 / 6)}
 
 @item rc_init_occupancy, vb
 rc_buf_initial_sz
 @code{(rc_init_occupancy * 1000 / vb)}
 
 @item rc_buffer_aggressivity
 rc_undershoot_pct
 
 @item skip_threshold
 rc_dropframe_thresh
 
 @item qcomp
 rc_2pass_vbr_bias_pct
 
 @item maxrate, vb
 rc_2pass_vbr_maxsection_pct
 @code{(maxrate * 100 / vb)}
 
 @item minrate, vb
 rc_2pass_vbr_minsection_pct
 @code{(minrate * 100 / vb)}
 
 @item minrate, maxrate, vb
 @code{VPX_CBR}
 @code{(minrate == maxrate == vb)}
 
 @item crf
 @code{VPX_CQ}, @code{VP8E_SET_CQ_LEVEL}
 
 @item quality
 @table @option
 @item @var{best}
 @code{VPX_DL_BEST_QUALITY}
 @item @var{good}
 @code{VPX_DL_GOOD_QUALITY}
 @item @var{realtime}
 @code{VPX_DL_REALTIME}
 @end table
 
 @item speed
 @code{VP8E_SET_CPUUSED}
 
 @item nr
 @code{VP8E_SET_NOISE_SENSITIVITY}
 
 @item mb_threshold
 @code{VP8E_SET_STATIC_THRESHOLD}
 
 @item slices
 @code{VP8E_SET_TOKEN_PARTITIONS}
 

 @item max-intra-rate
 @code{VP8E_SET_MAX_INTRA_BITRATE_PCT}
 
 @item force_key_frames
 @code{VPX_EFLAG_FORCE_KF}
 

 @item Alternate reference frame related
 @table @option
 @item vp8flags altref
 @code{VP8E_SET_ENABLEAUTOALTREF}
 @item @var{arnr_max_frames}
 @code{VP8E_SET_ARNR_MAXFRAMES}
 @item @var{arnr_type}
 @code{VP8E_SET_ARNR_TYPE}
 @item @var{arnr_strength}
 @code{VP8E_SET_ARNR_STRENGTH}
 @item @var{rc_lookahead}
 g_lag_in_frames
 @end table
 
 @item vp8flags error_resilient
 g_error_resilient
 

 @item aq_mode
 @code{VP9E_SET_AQ_MODE}
 

 @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 --full-help} 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 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 comparation 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 -vcodec libx264 -x264opts keyint=123:min-keyint=20 -an out.mkv
 @end example
 

 @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 preset
 Set the x265 preset.
 
 @item tune
 Set the x265 tune parameter.
 
 @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 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 mpeg2
 
 MPEG-2 video encoder.
 
 @subsection Options
 
 @table @option
 @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
 @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

 @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.
 

 @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 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