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 --enable-lib option. You can list all available encoders using the configure option --list-encoders.

You can disable all the encoders with the configure option --disable-encoders and selectively enable / disable single encoders with the options --enable-encoder=ENCODER / --disable-encoder=ENCODER.

The option -encoders of the ff* tools will display the list of enabled encoders.

Audio Encoders
**************

A description of some of the currently available audio encoders follows.

aac
===

Advanced Audio Coding (AAC) encoder.

This encoder is the default AAC encoder, natively implemented into FFmpeg. Its quality is on par or better than libfdk_aac at the default bitrate of 128kbps. This encoder also implements more options, profiles and samplerates than other encoders (with only the AAC-HE profile pending to be implemented) so this encoder has become the default and is the recommended choice.

Options
-------

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.

q
     Set quality for variable bit rate (VBR) mode. This option is valid only using the ffmpeg command-line tool. For library interface users, use global_quality.

cutoff
     Set cutoff frequency. If unspecified will allow the encoder to dynamically adjust the cutoff to improve clarity on low bitrates.

aac_coder
     Set AAC encoder coding method. Possible values:

     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 aac_is, aac_ms and aac_pns are enabled.

     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 aac_is or aac_pns options. Not currently recommended.

     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

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".

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".

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".

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".

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 -ar to decrease the samplerate.

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.

profile
     Sets the encoding profile, possible values:

     aac_low
          The default, AAC "Low-complexity" profile. Is the most compatible and produces decent quality.

     mpeg2_aac_low
          Equivalent to -profile:a aac_low -aac_pns 0. PNS was introduced with the MPEG4 specifications.

     aac_ltp
          Long term prediction profile, is enabled by and will enable the aac_ltp option. Introduced in MPEG4.

     aac_main
          Main-type prediction profile, is enabled by and will enable the aac_pred option. Introduced in MPEG2.

     If this option is unspecified it is set to aac_low.

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 AC3 encoder uses floating-point math, while the 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 AC3_FIXED encoder is not the default codec for any of the output formats, so it must be specified explicitly using the option -acodec ac3_fixed in order to use it.

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.

  * A/52:2010 - Digital Audio Compression (AC-3) (E-AC-3) Standard (http://www.atsc.org/cms/standards/a_52-2010.pdf)

  * A/54 - Guide to the Use of the ATSC Digital Television Standard (http://www.atsc.org/cms/standards/a_54a_with_corr_1.pdf)

  * Dolby Metadata Guide (http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/18_Metadata.Guide.pdf)

  * Dolby Digital Professional Encoding Guidelines (http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/46_DDEncodingGuidelines.pdf)

Metadata Control Options
........................

-per_frame_metadata BOOLEAN
     Allow Per-Frame Metadata. Specifies if the encoder should check for changing metadata for each frame.

     0
          The metadata values set at initialization will be used for every frame in the stream. (default)

     1
          Metadata values can be changed before encoding each frame.

Downmix Levels
..............

-center_mixlev 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:

     0.707
          Apply -3dB gain

     0.595
          Apply -4.5dB gain (default)

     0.500
          Apply -6dB gain

-surround_mixlev 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:

     0.707
          Apply -3dB gain

     0.500
          Apply -6dB gain (default)

     0.000
          Silence Surround Channel(s)

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.

-mixing_level 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 room_type option is not the default value, the mixing_level option must not be -1.

-room_type 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 mixing_level option and the room_type option have the default values.

     0
     notindicated
          Not Indicated (default)

     1
     large
          Large Room

     2
     small
          Small Room

Other Metadata Options
......................

-copyright BOOLEAN
     Copyright Indicator. Specifies whether a copyright exists for this audio.

     0
     off
          No Copyright Exists (default)

     1
     on
          Copyright Exists

-dialnorm 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.

-dsur_mode 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 NOT mean the encoder will actually apply Dolby Surround processing.

     0
     notindicated
          Not Indicated (default)

     1
     off
          Not Dolby Surround Encoded

     2
     on
          Dolby Surround Encoded

-original BOOLEAN
     Original Bit Stream Indicator. Specifies whether this audio is from the original source and not a copy.

     0
     off
          Not Original Source

     1
     on
          Original Source (default)

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 center_mixlev and surround_mixlev options if it supports the Alternate Bit Stream Syntax.

Extended Bitstream Information - Part 1
.......................................

-dmix_mode 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.

     0
     notindicated
          Not Indicated (default)

     1
     ltrt
          Lt/Rt Downmix Preferred

     2
     loro
          Lo/Ro Downmix Preferred

-ltrt_cmixlev 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.

     1.414
          Apply +3dB gain

     1.189
          Apply +1.5dB gain

     1.000
          Apply 0dB gain

     0.841
          Apply -1.5dB gain

     0.707
          Apply -3.0dB gain

     0.595
          Apply -4.5dB gain (default)

     0.500
          Apply -6.0dB gain

     0.000
          Silence Center Channel

-ltrt_surmixlev 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.

     0.841
          Apply -1.5dB gain

     0.707
          Apply -3.0dB gain

     0.595
          Apply -4.5dB gain

     0.500
          Apply -6.0dB gain (default)

     0.000
          Silence Surround Channel(s)

-loro_cmixlev 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.

     1.414
          Apply +3dB gain

     1.189
          Apply +1.5dB gain

     1.000
          Apply 0dB gain

     0.841
          Apply -1.5dB gain

     0.707
          Apply -3.0dB gain

     0.595
          Apply -4.5dB gain (default)

     0.500
          Apply -6.0dB gain

     0.000
          Silence Center Channel

-loro_surmixlev 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.

     0.841
          Apply -1.5dB gain

     0.707
          Apply -3.0dB gain

     0.595
          Apply -4.5dB gain

     0.500
          Apply -6.0dB gain (default)

     0.000
          Silence Surround Channel(s)

Extended Bitstream Information - Part 2
.......................................

-dsurex_mode MODE
     Dolby Surround EX Mode. Indicates whether the stream uses Dolby Surround EX (7.1 matrixed to 5.1). Using this option does NOT mean the encoder will actually apply Dolby Surround EX processing.

     0
     notindicated
          Not Indicated (default)

     1
     on
          Dolby Surround EX Off

     2
     off
          Dolby Surround EX On

-dheadphone_mode 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 NOT mean the encoder will actually apply Dolby Headphone processing.

     0
     notindicated
          Not Indicated (default)

     1
     on
          Dolby Headphone Off

     2
     off
          Dolby Headphone On

-ad_conv_type TYPE
     A/D Converter Type. Indicates whether the audio has passed through HDCD A/D conversion.

     0
     standard
          Standard A/D Converter (default)

     1
     hdcd
          HDCD A/D Converter

Other AC-3 Encoding Options
---------------------------

-stereo_rematrixing 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.

cutoff FREQUENCY
     Set lowpass cutoff frequency. If unspecified, the encoder selects a default determined by various other encoding parameters.

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.

-channel_coupling 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.

     -1
     auto
          Selected by Encoder (default)

     0
     off
          Disable Channel Coupling

     1
     on
          Enable Channel Coupling

-cpl_start_band 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 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.

     -1
     auto
          Selected by Encoder (default)

flac
====

FLAC (Free Lossless Audio Codec) Encoder

Options
-------

The following options are supported by FFmpeg's flac encoder.

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.

frame_size
     Sets the size of the frames in samples per channel.

lpc_coeff_precision
     Sets the LPC coefficient precision, valid values are from 1 to 15, 15 is the default.

lpc_type
     Sets the first stage LPC algorithm

     none
          LPC is not used

     fixed
          fixed LPC coefficients

     levinson

     cholesky

lpc_passes
     Number of passes to use for Cholesky factorization during LPC analysis

min_partition_order
     The minimum partition order

max_partition_order
     The maximum partition order

prediction_order_method

     estimation

     2level

     4level

     8level

     search
          Bruteforce search

     log

ch_mode
     Channel mode

     auto
          The mode is chosen automatically for each frame

     indep
          Channels are independently coded

     left_side

     right_side

     mid_side

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.

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.

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.

Options
-------

b
     Set bit rate in bits/s. If unspecified it uses the number of channels and the layout to make a good guess.

opus_delay
     Sets the maximum delay in milliseconds. Lower delays than 20ms will very quickly decrease quality.

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 --enable-libfdk-aac. The library is also incompatible with GPL, so if you allow the use of GPL, you should configure with --enable-gpl --enable-nonfree --enable-libfdk-aac.

This encoder is considered to produce output on par or worse at 128kbps to the the native FFmpeg AAC encoder but can often produce better sounding audio at identical or lower bitrates and has support for the AAC-HE profiles.

VBR encoding, enabled through the vbr or 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 http://sourceforge.net/p/opencore-amr/fdk-aac/.

Options
-------

The following options are mapped on the shared FFmpeg codec options.

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.

ar
     Set audio sampling rate (in Hz).

channels
     Set the number of audio channels.

flags +qscale
     Enable fixed quality, VBR (Variable Bit Rate) mode. Note that VBR is implicitly enabled when the vbr value is positive.

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.

profile
     Set audio profile.

     The following profiles are recognized:

     aac_low
          Low Complexity AAC (LC)

     aac_he
          High Efficiency AAC (HE-AAC)

     aac_he_v2
          High Efficiency AAC version 2 (HE-AACv2)

     aac_ld
          Low Delay AAC (LD)

     aac_eld
          Enhanced Low Delay AAC (ELD)

     If not specified it is set to aac_low.

The following are private options of the libfdk_aac encoder.

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.

eld_sbr
     Enable SBR (Spectral Band Replication) for ELD if set to 1, disabled if set to 0.

     Default value is 0.

signaling
     Set SBR/PS signaling style.

     It can assume one of the following values:

     default
          choose signaling implicitly (explicit hierarchical by default, implicit if global header is disabled)

     implicit
          implicit backwards compatible signaling

     explicit_sbr
          explicit SBR, implicit PS signaling

     explicit_hierarchical
          explicit hierarchical signaling

     Default value is default.

latm
     Output LATM/LOAS encapsulated data if set to 1, disabled if set to 0.

     Default value is 0.

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.

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 aac_low profile supports VBR encoding.

     VBR modes 1-5 correspond to roughly the following average bit rates:

     1
          32 kbps/channel

     2
          40 kbps/channel

     3
          48-56 kbps/channel

     4
          64 kbps/channel

     5
          about 80-96 kbps/channel

     Default value is 0.

Examples
--------

  * Use ffmpeg to convert an audio file to VBR AAC in an M4A (MP4) container:

          ffmpeg -i input.wav -codec:a libfdk_aac -vbr 3 output.m4a

  * Use ffmpeg to convert an audio file to CBR 64k kbps AAC, using the High-Efficiency AAC profile:

          ffmpeg -i input.wav -c:a libfdk_aac -profile:a aac_he -b:a 64k output.m4a

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 --enable-libmp3lame.

See libshine for a fixed-point MP3 encoder, although with a lower quality.

Options
-------

The following options are supported by the libmp3lame wrapper. The lame-equivalent of the options are listed in parentheses.

b (-b)
     Set bitrate expressed in bits/s for CBR or ABR. LAME bitrate is expressed in kilobits/s.

q (-V)
     Set constant quality setting for VBR. This option is valid only using the ffmpeg command-line tool. For library interface users, use global_quality.

compression_level (-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.

cutoff (--lowpass)
     Set lowpass cutoff frequency. If unspecified, the encoder dynamically adjusts the cutoff.

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 --nores option.

joint_stereo (-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.

abr (--abr)
     Enable the encoder to use ABR when set to 1. The lame --abr sets the target bitrate, while this options only tells FFmpeg to use ABR still relies on b to set bitrate.

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 --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 strict to unofficial or lower.

Options
-------

b
     Set bitrate in bits per second. Only the following bitrates are supported, otherwise libavcodec will round to the nearest valid bitrate.

     4750

     5150

     5900

     6700

     7400

     7950

     10200

     12200

dtx
     Allow discontinuous transmission (generate comfort noise) when set to 1. The default value is 0 (disabled).

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 --enable-libopus.

Option Mapping
--------------

Most libopus options are modelled after the opusenc utility from opus-tools. The following is an option mapping chart describing options supported by the libopus wrapper, and their opusenc-equivalent in parentheses.

b (bitrate)
     Set the bit rate in bits/s.  FFmpeg's b option is expressed in bits/s, while opusenc's bitrate in kilobits/s.

vbr (vbr, hard-cbr, and cvbr)
     Set VBR mode. The FFmpeg vbr option has the following valid arguments, with the opusenc equivalent options in parentheses:

     off (hard-cbr)
          Use constant bit rate encoding.

     on (vbr)
          Use variable bit rate encoding (the default).

     constrained (cvbr)
          Use constrained variable bit rate encoding.

compression_level (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.

frame_duration (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.

packet_loss (expect-loss)
     Set expected packet loss percentage. The default is 0.

application (N.A.)
     Set intended application type. Valid options are listed below:

     voip
          Favor improved speech intelligibility.

     audio
          Favor faithfulness to the input (the default).

     lowdelay
          Restrict to only the lowest delay modes.

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).

mapping_family (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.

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).

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 http://sourceforge.net/projects/libshine-fxp/. We only support the updated fork by the Savonet/Liquidsoap project at https://github.com/savonet/shine.

Requires the presence of the libshine headers and library during configuration. You need to explicitly configure the build with --enable-libshine.

See also libmp3lame.

Options
-------

The following options are supported by the libshine wrapper. The shineenc-equivalent of the options are listed in parentheses.

b (-b)
     Set bitrate expressed in bits/s for CBR. shineenc -b option is expressed in kilobits/s.

libtwolame
==========

TwoLAME MP2 encoder wrapper.

Requires the presence of the libtwolame headers and library during configuration. You need to explicitly configure the build with --enable-libtwolame.

Options
-------

The following options are supported by the libtwolame wrapper. The twolame-equivalent options follow the FFmpeg ones and are in parentheses.

b (-b)
     Set bitrate expressed in bits/s for CBR. twolame b option is expressed in kilobits/s. Default value is 128k.

q (-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 ffmpeg command-line tool. For library interface users, use global_quality.

mode (--mode)
     Set the mode of the resulting audio. Possible values:

     auto
          Choose mode automatically based on the input. This is the default.

     stereo
          Stereo

     joint_stereo
          Joint stereo

     dual_channel
          Dual channel

     mono
          Mono

psymodel (--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.

energy_levels (--energy)
     Enable energy levels extensions when set to 1. The default value is 0 (disabled).

error_protection (--protect)
     Enable CRC error protection when set to 1. The default value is 0 (disabled).

copyright (--copyright)
     Set MPEG audio copyright flag when set to 1. The default value is 0 (disabled).

original (--original)
     Set MPEG audio original flag when set to 1. The default value is 0 (disabled).

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 --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 strict to unofficial or lower.

Options
-------

b
     Set bitrate in bits/s. Only the following bitrates are supported, otherwise libavcodec will round to the nearest valid bitrate.

     6600

     8850

     12650

     14250

     15850

     18250

     19850

     23050

     23850

dtx
     Allow discontinuous transmission (generate comfort noise) when set to 1. The default value is 0 (disabled).

libvorbis
=========

libvorbis encoder wrapper.

Requires the presence of the libvorbisenc headers and library during configuration. You need to explicitly configure the build with --enable-libvorbis.

Options
-------

The following options are supported by the libvorbis wrapper. The 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 oggenc's documentations. See http://xiph.org/vorbis/, http://wiki.xiph.org/Vorbis-tools, and oggenc(1).

b (-b)
     Set bitrate expressed in bits/s for ABR. oggenc -b is expressed in kilobits/s.

q (-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 3.0.

     This option is valid only using the ffmpeg command-line tool. For library interface users, use global_quality.

cutoff (--advanced-encode-option lowpass_frequency=N)
     Set cutoff bandwidth in Hz, a value of 0 disables cutoff. oggenc's related option is expressed in kHz. The default value is 0 (cutoff disabled).

minrate (-m)
     Set minimum bitrate expressed in bits/s. oggenc -m is expressed in kilobits/s.

maxrate (-M)
     Set maximum bitrate expressed in bits/s. oggenc -M is expressed in kilobits/s. This only has effect on ABR mode.

iblock (--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.

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 --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 wavpackenc.

Options
-------

wavpack command line utility's corresponding options are listed in parentheses, if any.

frame_size (--blocksize)
     Default is 32768.

compression_level
     Set speed vs. compression tradeoff. Acceptable arguments are listed below:

     0 (-f)
          Fast mode.

     1
          Normal (default) settings.

     2 (-h)
          High quality.

     3 (-hh)
          Very high quality.

     4-8 (-hh -xEXTRAPROC)
          Same as 3, but with extra processing enabled.

          4 is the same as -x2 and 8 is the same as -x6.

mjpeg
=====

Motion JPEG encoder.

Options
-------

huffman
     Set the huffman encoding strategy. Possible values:

     default
          Use the default huffman tables. This is the default strategy.

     optimal
          Compute and use optimal huffman tables.

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 libwavpack.

Options
-------

The equivalent options for wavpack command line utility are listed in parentheses.

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 the Codec Options chapter.

frame_size (--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 libavcodec/wavpackenc.c.

compression_level (-f, -h, -hh, and -x)
     This option's syntax is consistent with libwavpack's.

Private options
...............

joint_stereo (-j)
     Set whether to enable joint stereo. Valid values are:

     on (1)
          Force mid/side audio encoding.

     off (0)
          Force left/right audio encoding.

     auto
          Let the encoder decide automatically.

optimize_mono
     Set whether to enable optimization for mono. This option is only effective for non-mono streams. Available values:

     on
          enabled

     off
          disabled

Video Encoders
**************

A description of some of the currently available video encoders follows.

Hap
===

Vidvox Hap video encoder.

Options
-------

format INTEGER
     Specifies the Hap format to encode.

     hap

     hap_alpha

     hap_q

     Default value is hap.

chunks 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 1.

compressor INTEGER
     Specifies the second-stage compressor to use. If set to none, chunks will be limited to 1, as chunked uncompressed frames offer no benefit.

     none

     snappy

     Default value is snappy.

jpeg2000
========

The native jpeg 2000 encoder is lossy by default, the -q:v option can be used to set the encoding quality. Lossless encoding can be selected with -pred 1.

Options
-------

format
     Can be set to either j2k or jp2 (the default) that makes it possible to store non-rgb pix_fmts.

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 --enable-libkvazaar.

Options
-------

b
     Set target video bitrate in bit/s and enable rate control.

kvazaar-params
     Set kvazaar parameters as a list of NAME=VALUE pairs separated by commas (,). See kvazaar documentation for a list of options.

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 --enable-libopenh264. The library is detected using pkg-config.

For more information about the library see http://www.openh264.org.

Options
-------

The following FFmpeg global options affect the configurations of the libopenh264 encoder.

b
     Set the bitrate (as a number of bits per second).

g
     Set the GOP size.

maxrate
     Set the max bitrate (as a number of bits per second).

flags +global_header
     Set global header in the bitstream.

slices
     Set the number of slices, used in parallelized encoding. Default value is 0. This is only used when slice_mode is set to fixed.

slice_mode
     Set slice mode. Can assume one of the following possible values:

     fixed
          a fixed number of slices

     rowmb
          one slice per row of macroblocks

     auto
          automatic number of slices according to number of threads

     dyn
          dynamic slicing

     Default value is auto.

loopfilter
     Enable loop filter, if set to 1 (automatically enabled). To disable set a value of 0.

profile
     Set profile restrictions. If set to the value of main enable CABAC (set the SEncParamExt.iEntropyCodingModeFlag flag to 1).

max_nal_size
     Set maximum NAL size in bytes.

allow_skip_frames
     Allow skipping frames to hit the target bitrate if set to 1.

libtheora
=========

libtheora Theora encoder wrapper.

Requires the presence of the libtheora headers and library during configuration. You need to explicitly configure the build with --enable-libtheora.

For more information about the libtheora project see http://www.theora.org/.

Options
-------

The following global options are mapped to internal libtheora options which affect the quality and the bitrate of the encoded stream.

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.

flags
     Used to enable constant quality mode (VBR) encoding through the qscale flag, and to enable the pass1 and pass2 modes.

g
     Set the GOP size.

global_quality
     Set the global quality as an integer in lambda units.

     Only relevant when VBR mode is enabled with flags +qscale. The value is converted to QP units by dividing it by 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.

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 ffmpeg command-line tool. For library interface users, use global_quality.

Examples
--------

  * Set maximum constant quality (VBR) encoding with ffmpeg:

          ffmpeg -i INPUT -codec:v libtheora -q:v 10 OUTPUT.ogg

  * Use ffmpeg to convert a CBR 1000 kbps Theora video stream:

          ffmpeg -i INPUT -codec:v libtheora -b:v 1000k OUTPUT.ogg

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 --enable-libvpx.

Options
-------

The following options are supported by the libvpx wrapper. The 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 the Codec Options chapter.

To get more documentation of the libvpx options, invoke the command ffmpeg -h encoder=libvpx, ffmpeg -h encoder=libvpx-vp9 or vpxenc --help. Further information is available in the libvpx API documentation.

b (target-bitrate)
     Set bitrate in bits/s. Note that FFmpeg's b option is expressed in bits/s, while vpxenc's target-bitrate is in kilobits/s.

g (kf-max-dist)

keyint_min (kf-min-dist)

qmin (min-q)

qmax (max-q)

bufsize (buf-sz, buf-optimal-sz)
     Set ratecontrol buffer size (in bits). Note vpxenc's options are specified in milliseconds, the libvpx wrapper converts this value as follows: buf-sz = bufsize * 1000 / bitrate, buf-optimal-sz = bufsize * 1000 / bitrate * 5 / 6.

rc_init_occupancy (buf-initial-sz)
     Set number of bits which should be loaded into the rc buffer before decoding starts. Note vpxenc's option is specified in milliseconds, the libvpx wrapper converts this value as follows: rc_init_occupancy * 1000 / bitrate.

undershoot-pct
     Set datarate undershoot (min) percentage of the target bitrate.

overshoot-pct
     Set datarate overshoot (max) percentage of the target bitrate.

skip_threshold (drop-frame)

qcomp (bias-pct)

maxrate (maxsection-pct)
     Set GOP max bitrate in bits/s. Note vpxenc's option is specified as a percentage of the target bitrate, the libvpx wrapper converts this value as follows: (maxrate * 100 / bitrate).

minrate (minsection-pct)
     Set GOP min bitrate in bits/s. Note vpxenc's option is specified as a percentage of the target bitrate, the libvpx wrapper converts this value as follows: (minrate * 100 / bitrate).

minrate, maxrate, b end-usage=cbr
     (minrate == maxrate == bitrate).

crf (end-usage=cq, cq-level)

tune (tune)

     psnr (psnr)

     ssim (ssim)

quality, deadline (deadline)

     best
          Use best quality deadline. Poorly named and quite slow, this option should be avoided as it may give worse quality output than good.

     good
          Use good quality deadline. This is a good trade-off between speed and quality when used with the cpu-used option.

     realtime
          Use realtime quality deadline.

speed, cpu-used (cpu-used)
     Set quality/speed ratio modifier. Higher values speed up the encode at the cost of quality.

nr (noise-sensitivity)

static-thresh
     Set a change threshold on blocks below which they will be skipped by the encoder.

slices (token-parts)
     Note that FFmpeg's slices option gives the total number of partitions, while vpxenc's token-parts is given as log2(partitions).

max-intra-rate
     Set maximum I-frame bitrate as a percentage of the target bitrate. A value of 0 means unlimited.

force_key_frames
     VPX_EFLAG_FORCE_KF

Alternate reference frame related

     auto-alt-ref
          Enable use of alternate reference frames (2-pass only). Values greater than 1 enable multi-layer alternate reference frames (VP9 only).

     arnr-max-frames
          Set altref noise reduction max frame count.

     arnr-type
          Set altref noise reduction filter type: backward, forward, centered.

     arnr-strength
          Set altref noise reduction filter strength.

     rc-lookahead, lag-in-frames (lag-in-frames)
          Set number of frames to look ahead for frametype and ratecontrol.

error-resilient
     Enable error resiliency features.

VP9-specific options

     lossless
          Enable lossless mode.

     tile-columns
          Set number of tile columns to use. Note this is given as log2(tile_columns). For example, 8 tile columns would be requested by setting the tile-columns option to 3.

     tile-rows
          Set number of tile rows to use. Note this is given as log2(tile_rows). For example, 4 tile rows would be requested by setting the tile-rows option to 2.

     frame-parallel
          Enable frame parallel decodability features.

     aq-mode
          Set adaptive quantization mode (0: off (default), 1: variance 2: complexity, 3: cyclic refresh, 4: equator360).

     colorspace color-space
          Set input color space. The VP9 bitstream supports signaling the following colorspaces:

          rgb sRGB

          bt709 bt709

          unspecified unknown

          bt470bg bt601

          smpte170m smpte170

          smpte240m smpte240

          bt2020_ncl bt2020

     row-mt BOOLEAN
          Enable row based multi-threading.

     tune-content
          Set content type: default (0), screen (1), film (2).

     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.

     enable-tpl BOOLEAN
          Enable temporal dependency model.

For more information about libvpx see: http://www.webmproject.org/

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.

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.

Options
-------

-lossless BOOLEAN
     Enables/Disables use of lossless mode. Default is 0.

-compression_level 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 METHOD option in libwebp. The valid range is 0 to 6. Default is 4.

-qscale 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 GLOBAL_QUALITY and must be multiplied by FF_QP2LAMBDA.

-preset TYPE
     Configuration preset. This does some automatic settings based on the general type of the image.

     none
          Do not use a preset.

     default
          Use the encoder default.

     picture
          Digital picture, like portrait, inner shot

     photo
          Outdoor photograph, with natural lighting

     drawing
          Hand or line drawing, with high-contrast details

     icon
          Small-sized colorful images

     text
          Text-like

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 --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 x264opts and x264-params private options allows one to pass a list of key=value tuples as accepted by the libx264 x264_param_parse function.

The x264 project website is at 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.

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.

Options
-------

The following options are supported by the libx264 wrapper. The 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 the Codec Options chapter.

To get a more accurate and extensive documentation of the libx264 options, invoke the command x264 --fullhelp or consult the libx264 documentation.

b (bitrate)
     Set bitrate in bits/s. Note that FFmpeg's b option is expressed in bits/s, while x264's bitrate is in kilobits/s.

bf (bframes)

g (keyint)

qmin (qpmin)
     Minimum quantizer scale.

qmax (qpmax)
     Maximum quantizer scale.

qdiff (qpstep)
     Maximum difference between quantizer scales.

qblur (qblur)
     Quantizer curve blur

qcomp (qcomp)
     Quantizer curve compression factor

refs (ref)
     Number of reference frames each P-frame can use. The range is from 0-16.

sc_threshold (scenecut)
     Sets the threshold for the scene change detection.

trellis (trellis)
     Performs Trellis quantization to increase efficiency. Enabled by default.

nr  (nr)

me_range (merange)
     Maximum range of the motion search in pixels.

me_method (me)
     Set motion estimation method. Possible values in the decreasing order of speed:

     dia (dia)

     epzs (dia)
          Diamond search with radius 1 (fastest). epzs is an alias for dia.

     hex (hex)
          Hexagonal search with radius 2.

     umh (umh)
          Uneven multi-hexagon search.

     esa (esa)
          Exhaustive search.

     tesa (tesa)
          Hadamard exhaustive search (slowest).

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.

subq (subme)
     Sub-pixel motion estimation method.

b_strategy (b-adapt)
     Adaptive B-frame placement decision algorithm. Use only on first-pass.

keyint_min (min-keyint)
     Minimum GOP size.

coder
     Set entropy encoder. Possible values:

     ac
          Enable CABAC.

     vlc
          Enable CAVLC and disable CABAC. It generates the same effect as x264's --no-cabac option.

cmp
     Set full pixel motion estimation comparison algorithm. Possible values:

     chroma
          Enable chroma in motion estimation.

     sad
          Ignore chroma in motion estimation. It generates the same effect as x264's --no-chroma-me option.

threads (threads)
     Number of encoding threads.

thread_type
     Set multithreading technique. Possible values:

     slice
          Slice-based multithreading. It generates the same effect as x264's --sliced-threads option.

     frame
          Frame-based multithreading.

flags
     Set encoding flags. It can be used to disable closed GOP and enable open GOP by setting it to -cgop. The result is similar to the behavior of x264's --open-gop option.

rc_init_occupancy (vbv-init)

preset (preset)
     Set the encoding preset.

tune (tune)
     Set tuning of the encoding params.

profile (profile)
     Set profile restrictions.

fastfirstpass
     Enable fast settings when encoding first pass, when set to 1. When set to 0, it has the same effect of x264's --slow-firstpass option.

crf (crf)
     Set the quality for constant quality mode.

crf_max (crf-max)
     In CRF mode, prevents VBV from lowering quality beyond this point.

qp (qp)
     Set constant quantization rate control method parameter.

aq-mode (aq-mode)
     Set AQ method. Possible values:

     none (0)
          Disabled.

     variance (1)
          Variance AQ (complexity mask).

     autovariance (2)
          Auto-variance AQ (experimental).

aq-strength (aq-strength)
     Set AQ strength, reduce blocking and blurring in flat and textured areas.

psy
     Use psychovisual optimizations when set to 1. When set to 0, it has the same effect as x264's --no-psy option.

psy-rd  (psy-rd)
     Set strength of psychovisual optimization, in PSY-RD:PSY-TRELLIS format.

rc-lookahead (rc-lookahead)
     Set number of frames to look ahead for frametype and ratecontrol.

weightb
     Enable weighted prediction for B-frames when set to 1. When set to 0, it has the same effect as x264's --no-weightb option.

weightp (weightp)
     Set weighted prediction method for P-frames. Possible values:

     none (0)
          Disabled

     simple (1)
          Enable only weighted refs

     smart (2)
          Enable both weighted refs and duplicates

ssim (ssim)
     Enable calculation and printing SSIM stats after the encoding.

intra-refresh (intra-refresh)
     Enable the use of Periodic Intra Refresh instead of IDR frames when set to 1.

avcintra-class (class)
     Configure the encoder to generate AVC-Intra. Valid values are 50,100 and 200

bluray-compat (bluray-compat)
     Configure the encoder to be compatible with the bluray standard. It is a shorthand for setting "bluray-compat=1 force-cfr=1".

b-bias (b-bias)
     Set the influence on how often B-frames are used.

b-pyramid (b-pyramid)
     Set method for keeping of some B-frames as references. Possible values:

     none (none)
          Disabled.

     strict (strict)
          Strictly hierarchical pyramid.

     normal (normal)
          Non-strict (not Blu-ray compatible).

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 x264's --no-mixed-refs option.

8x8dct
     Enable adaptive spatial transform (high profile 8x8 transform) when set to 1. When set to 0, it has the same effect as x264's --no-8x8dct option.

fast-pskip
     Enable early SKIP detection on P-frames when set to 1. When set to 0, it has the same effect as x264's --no-fast-pskip option.

aud (aud)
     Enable use of access unit delimiters when set to 1.

mbtree
     Enable use macroblock tree ratecontrol when set to 1. When set to 0, it has the same effect as x264's --no-mbtree option.

deblock (deblock)
     Set loop filter parameters, in ALPHA:BETA form.

cplxblur (cplxblur)
     Set fluctuations reduction in QP (before curve compression).

partitions (partitions)
     Set partitions to consider as a comma-separated list of. Possible values in the list:

     p8x8
          8x8 P-frame partition.

     p4x4
          4x4 P-frame partition.

     b8x8
          4x4 B-frame partition.

     i8x8
          8x8 I-frame partition.

     i4x4
          4x4 I-frame partition. (Enabling p4x4 requires p8x8 to be enabled. Enabling i8x8 requires adaptive spatial transform (8x8dct option) to be enabled.)

     none (none)
          Do not consider any partitions.

     all (all)
          Consider every partition.

direct-pred (direct)
     Set direct MV prediction mode. Possible values:

     none (none)
          Disable MV prediction.

     spatial (spatial)
          Enable spatial predicting.

     temporal (temporal)
          Enable temporal predicting.

     auto (auto)
          Automatically decided.

slice-max-size (slice-max-size)
     Set the limit of the size of each slice in bytes. If not specified but RTP payload size (ps) is specified, that is used.

stats (stats)
     Set the file name for multi-pass stats.

nal-hrd (nal-hrd)
     Set signal HRD information (requires vbv-bufsize to be set). Possible values:

     none (none)
          Disable HRD information signaling.

     vbr (vbr)
          Variable bit rate.

     cbr (cbr)
          Constant bit rate (not allowed in MP4 container).

x264opts (N.A.)
     Set any x264 option, see x264 --fullhelp for a list.

     Argument is a list of KEY=VALUE couples separated by ":". In FILTER and 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 ffmpeg:

          ffmpeg -i foo.mpg -c:v libx264 -x264opts keyint=123:min-keyint=20 -an out.mkv

a53cc BOOLEAN
     Import closed captions (which must be ATSC compatible format) into output. Only the mpeg2 and h264 decoders provide these. Default is 1 (on).

x264-params (N.A.)
     Override the x264 configuration using a :-separated list of key=value parameters.

     This option is functionally the same as the x264opts, but is duplicated for compatibility with the Libav fork.

     For example to specify libx264 encoding options with ffmpeg:

          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

Encoding ffpresets for common usages are provided so they can be used with the general presets system (e.g. passing the pre option).

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 --enable-libx265.

Options
-------

preset
     Set the x265 preset.

tune
     Set the x265 tune parameter.

profile
     Set profile restrictions.

crf
     Set the quality for constant quality mode.

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.

x265-params
     Set x265 options using a list of KEY=VALUE couples separated by ":". See x265 --help for a list of options.

     For example to specify libx265 encoding options with -x265-params:

          ffmpeg -i input -c:v libx265 -x265-params crf=26:psy-rd=1 output.mp4

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 --enable-libxvid --enable-gpl.

The native mpeg4 encoder supports the MPEG-4 Part 2 format, so users can encode to this format without this library.

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 the Codec Options chapter for their documentation. The other shared options which are not listed have no effect for the libxvid encoder.

b

g

qmin

qmax

mpeg_quant

threads

bf

b_qfactor

b_qoffset

flags
     Set specific encoding flags. Possible values:

     mv4
          Use four motion vector by macroblock.

     aic
          Enable high quality AC prediction.

     gray
          Only encode grayscale.

     gmc
          Enable the use of global motion compensation (GMC).

     qpel
          Enable quarter-pixel motion compensation.

     cgop
          Enable closed GOP.

     global_header
          Place global headers in extradata instead of every keyframe.

trellis

me_method
     Set motion estimation method. Possible values in decreasing order of speed and increasing order of quality:

     zero
          Use no motion estimation (default).

     phods

     x1

     log
          Enable advanced diamond zonal search for 16x16 blocks and half-pixel refinement for 16x16 blocks. x1 and log are aliases for phods.

     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.

     full
          Enable all of the things described above, plus extended 16x16 and 8x8 blocks search.

mbd
     Set macroblock decision algorithm. Possible values in the increasing order of quality:

     simple
          Use macroblock comparing function algorithm (default).

     bits
          Enable rate distortion-based half pixel and quarter pixel refinement for 16x16 blocks.

     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.

lumi_aq
     Enable lumi masking adaptive quantization when set to 1. Default is 0 (disabled).

variance_aq
     Enable variance adaptive quantization when set to 1. Default is 0 (disabled).

     When combined with 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.

ssim
     Set structural similarity (SSIM) displaying method. Possible values:

     off
          Disable displaying of SSIM information.

     avg
          Output average SSIM at the end of encoding to stdout. The format of showing the average SSIM is:

               Average SSIM: %f

          For users who are not familiar with C, %f means a float number, or a decimal (e.g. 0.939232).

     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:

                      SSIM: avg: %1.3f min: %1.3f max: %1.3f

          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).

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.

mpeg2
=====

MPEG-2 video encoder.

Options
-------

seq_disp_ext INTEGER
     Specifies if the encoder should write a sequence_display_extension to the output.

     -1
     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.

     0
     never
          Never write it.

     1
     always
          Always write it.

video_format INTEGER
     Specifies the video_format written into the sequence display extension indicating the source of the video pictures. The default is unspecified, can be component, pal, ntsc, secam or mac. For maximum compatibility, use component.

png
===

PNG image encoder.

Private options
---------------

dpi INTEGER
     Set physical density of pixels, in dots per inch, unset by default

dpm INTEGER
     Set physical density of pixels, in dots per meter, unset by default

ProRes
======

Apple ProRes encoder.

FFmpeg contains 2 ProRes encoders, the prores-aw and prores-ks encoder. The used encoder can be chosen with the -vcodec option.

Private Options for prores-ks
-----------------------------

profile INTEGER
     Select the ProRes profile to encode

     proxy

     lt

     standard

     hq

     4444

     4444xq

quant_mat INTEGER
     Select quantization matrix.

     auto

     default

     proxy

     lt

     standard

     hq

     If set to AUTO, the matrix matching the profile will be picked. If not set, the matrix providing the highest quality, DEFAULT, will be picked.

bits_per_mb INTEGER
     How many bits to allot for coding one macroblock. Different profiles use between 200 and 2400 bits per macroblock, the maximum is 8000.

mbs_per_slice INTEGER
     Number of macroblocks in each slice (1-8); the default value (8) should be good in almost all situations.

vendor STRING
     Override the 4-byte vendor ID. A custom vendor ID like APL0 would claim the stream was produced by the Apple encoder.

alpha_bits INTEGER
     Specify number of bits for alpha component. Possible values are 0, 8 and 16. Use 0 to disable alpha plane coding.

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 bits_per_mb limit will improve the speed.

For the fastest encoding speed set the qscale parameter (4 is the recommended value) and do not set a size constraint.

QSV encoders
============

The family of Intel QuickSync Video encoders (MPEG-2, H.264 and HEVC)

The ratecontrol method is selected as follows:

  * When global_quality is specified, a quality-based mode is used. Specifically this means either

       - CQP - constant quantizer scale, when the qscale codec flag is also set (the -qscale ffmpeg option).

       - LA_ICQ - intelligent constant quality with lookahead, when the look_ahead option is also set.

       - ICQ -- intelligent constant quality otherwise.

  * Otherwise, a bitrate-based mode is used. For all of those, you should specify at least the desired average bitrate with the b option.

       - LA - VBR with lookahead, when the look_ahead option is specified.

       - VCM - video conferencing mode, when the vcm option is set.

       - CBR - constant bitrate, when maxrate is specified and equal to the average bitrate.

       - VBR - variable bitrate, when maxrate is specified, but is higher than the average bitrate.

       - AVBR - average VBR mode, when maxrate is not specified. This mode is further configured by the avbr_accuracy and avbr_convergence options.

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 VERBOSE or higher to see the actual settings used by the QSV runtime.

Additional libavcodec global options are mapped to MSDK options as follows:

  * g/gop_size -> GopPicSize

  * bf/max_b_frames+1 -> GopRefDist

  * rc_init_occupancy/rc_initial_buffer_occupancy -> InitialDelayInKB

  * slices -> NumSlice

  * refs -> NumRefFrame

  * b_strategy/b_frame_strategy -> BRefType

  * cgop/CLOSED_GOP codec flag -> GopOptFlag

  * For the CQP mode, the i_qfactor/i_qoffset and b_qfactor/b_qoffset set the difference between QPP and QPI, and QPP and QPB respectively.

  * Setting the coder option to the value VLC will make the H.264 encoder use CAVLC instead of CABAC.

snow
====

Options
-------

iterative_dia_size
     dia size for the iterative motion estimation

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 hwupload filter to upload them to the GPU.

The following standard libavcodec options are used:

  * g / gop_size

  * bf / max_b_frames

  * profile

     If not set, this will be determined automatically from the format of the input frames and the profiles supported by the driver.

  * level

  * b / bit_rate

  * maxrate / rc_max_rate

  * bufsize / rc_buffer_size

  * rc_init_occupancy / rc_initial_buffer_occupancy

  * compression_level

     Speed / quality tradeoff: higher values are faster / worse quality.

  * q / global_quality

     Size / quality tradeoff: higher values are smaller / worse quality.

  * qmin

  * qmax

  * i_qfactor / i_quant_factor

  * i_qoffset / i_quant_offset

  * b_qfactor / b_quant_factor

  * b_qoffset / b_quant_offset

  * slices

All encoders support the following options:

  * 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.

Each encoder also has its own specific options:

h264_vaapi
     profile sets the value of profile_idc and the constraint_set*_flags. level sets the value of level_idc.

     coder
          Set entropy encoder (default is cabac).  Possible values:

          ac

          cabac
               Use CABAC.

          vlc

          cavlc
               Use CAVLC.

     aud
          Include access unit delimiters in the stream (not included by default).

     sei
          Set SEI message types to include. Some combination of the following values:

          identifier
               Include a user_data_unregistered message containing information about the encoder.

          timing
               Include picture timing parameters (buffering_period and pic_timing messages).

          recovery_point
               Include recovery points where appropriate (recovery_point messages).

hevc_vaapi
     profile and level set the values of general_profile_idc and general_level_idc respectively.

     aud
          Include access unit delimiters in the stream (not included by default).

     tier
          Set general_tier_flag.  This may affect the level chosen for the stream if it is not explicitly specified.

     sei
          Set SEI message types to include. Some combination of the following values:

          hdr
               Include HDR metadata if the input frames have it (mastering_display_colour_volume and content_light_level messages).

mjpeg_vaapi
     Only baseline DCT encoding is supported.  The encoder always uses the standard quantisation and huffman tables - 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.

     jfif
          Include JFIF header in each frame (not included by default).

     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.

mpeg2_vaapi
     profile and level set the value of profile_and_level_indication.

vp8_vaapi
     B-frames are not supported.

     global_quality sets the q_idx used for non-key frames (range 0-127).

     loop_filter_level

     loop_filter_sharpness
          Manually set the loop filter parameters.

vp9_vaapi
     global_quality sets the q_idx used for P-frames (range 0-255).

     loop_filter_level

     loop_filter_sharpness
          Manually set the loop filter parameters.

     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 vp9_raw_reorder bitstream filter to modify the output stream to display frames in the correct order.

     Only normal frames are produced - the vp9_superframe bitstream filter may be required to produce a stream usable with all decoders.

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).

Options
-------

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.

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.

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 wavelet_depth over 3.

wavelet_type
     Sets the transform type. Currently only 5_3 (LeGall) and 9_7 (Deslauriers-Dubuc) are implemented, with 9_7 being the one with better compression and thus is the default.

slice_width

slice_height
     Sets the slice size for each slice. Larger values result in better compression. For compatibility with other more limited decoders use slice_width of 32 and slice_height of 8.

tolerance
     Sets the undershoot tolerance of the rate control system in percent. This is to prevent an expensive search from being run.

qm
     Sets the quantization matrix preset to use by default or when wavelet_depth is set to 5

       - 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.

       - FLAT Use a completely zeroed out quantization matrix. This increases PSNR but might reduce perception. Use in bogus benchmarks.

       - COLOR Reduces detail but attempts to preserve color at extremely low bitrates.

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 --enable-libxavs2.

Options
-------

lcu_row_threads
     Set the number of parallel threads for rows from 1 to 8 (default 5).

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.

qp
     Set the xavs2 quantization parameter from 1 to 63 (default 34). This is used to set the qp value under constant-QP mode.

max_qp
     Set the max qp for rate control from 1 to 63 (default 55).

min_qp
     Set the min qp for rate control from 1 to 63 (default 20).

speed_level
     Set the Speed level from 0 to 9 (default 0). Higher is better but slower.

log_level
     Set the log level from -1 to 3 (default 0). -1: none, 0: error, 1: warning, 2: info, 3: debug.

xavs2-params
     Set xavs2 options using a list of KEY=VALUE couples separated by ":".

     For example to specify libxavs2 encoding options with -xavs2-params:

          ffmpeg -i input -c:v libxavs2 -xavs2-params preset_level=5 output.avs2

Subtitles Encoders
******************

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.

Options
-------

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.