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.

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 is the default 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.

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 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, it's 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 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.

eld_v2
     Enable ELDv2 (LD-MPS extension for ELD stereo signals) for ELDv2 if set to 1, disabled if set to 0.

     Note that option is available when fdk-aac version (AACENCODER_LIB_VL0.AACENCODER_LIB_VL1.AACENCODER_LIB_VL2) > (4.0.0).

     Default value is 0.

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.

frame_length
     Set the audio frame length in samples. Default value is the internal default of the library. Refer to the library's documentation for information about supported values.

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

liblc3
======

liblc3 LC3 (Low Complexity Communication Codec) encoder wrapper.

Requires the presence of the liblc3 headers and library during configuration. You need to explicitly configure the build with --enable-liblc3.

This encoder has support for the Bluetooth SIG LC3 codec for the LE Audio protocol, and the following features of LC3plus:

  * Frame duration of 2.5 and 5ms.

  * High-Resolution mode, 48 KHz, and 96 kHz sampling rates.

For more information see the liblc3 project at https://github.com/google/liblc3.

Options
-------

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

b BITRATE
     Set the bit rate in bits/s. This will determine the fixed size of the encoded frames, for a selected frame duration.

ar FREQUENCY
     Set the audio sampling rate (in Hz).

channels
     Set the number of audio channels.

frame_duration
     Set the audio frame duration in milliseconds. Default value is 10ms. Allowed frame durations are 2.5ms, 5ms, 7.5ms and 10ms. LC3 (Bluetooth LE Audio), allows 7.5ms and 10ms; and LC3plus 2.5ms, 5ms and 10ms.

     The 10ms frame duration is available in LC3 and LC3 plus standard. In this mode, the produced bitstream can be referenced either as LC3 or LC3plus.

high_resolution BOOLEAN
     Enable the high-resolution mode if set to 1. The high-resolution mode is available with all LC3plus frame durations and for a sampling rate of 48 KHz, and 96 KHz.

     The encoder automatically turns off this mode at lower sampling rates and activates it at 96 KHz.

     This mode should be preferred at high bitrates. In this mode, the audio bandwidth is always up to the Nyquist frequency, compared to LC3 at 48 KHz, which limits the bandwidth to 20 KHz.

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.

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

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

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.

fec (n/a)
     Enable inband forward error correction. packet_loss must be non-zero to take advantage - frequency of FEC 'side-data' is proportional to expected packet loss. Default is disabled.

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 by disabling voice-optimized 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). Note that libopus forces a wideband cutoff for bitrates < 15 kbps, unless CELT-only (application set to lowdelay) mode is used.

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.

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.

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)

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.

a64_multi, a64_multi5
=====================

A64 / Commodore 64 multicolor charset encoder. a64_multi5 is extended with 5th color (colram).

Cinepak
=======

Cinepak aka CVID encoder. Compatible with Windows 3.1 and vintage MacOS.

Options
-------

g INTEGER
     Keyframe interval. A keyframe is inserted at least every -g frames, sometimes sooner.

q:v INTEGER
     Quality factor. Lower is better. Higher gives lower bitrate. The following table lists bitrates when encoding akiyo_cif.y4m for various values of -q:v with -g 100:

     -q:v 1 1918 kb/s

     -q:v 2 1735 kb/s

     -q:v 4 1500 kb/s

     -q:v 10 1041 kb/s

     -q:v 20 826 kb/s

     -q:v 40 553 kb/s

     -q:v 100 394 kb/s

     -q:v 200 312 kb/s

     -q:v 400 266 kb/s

     -q:v 1000 237 kb/s

max_extra_cb_iterations INTEGER
     Max extra codebook recalculation passes, more is better and slower.

skip_empty_cb BOOLEAN
     Avoid wasting bytes, ignore vintage MacOS decoder.

max_strips INTEGER
min_strips INTEGER
     The minimum and maximum number of strips to use. Wider range sometimes improves quality. More strips is generally better quality but costs more bits. Fewer strips tend to yield more keyframes. Vintage compatible is 1..3.

strip_number_adaptivity INTEGER
     How much number of strips is allowed to change between frames. Higher is better but slower.

GIF
===

GIF image/animation encoder.

Options
-------

gifflags INTEGER
     Sets the flags used for GIF encoding.

     offsetting
          Enables picture offsetting.

          Default is enabled.

     transdiff
          Enables transparency detection between frames.

          Default is enabled.

gifimage INTEGER
     Enables encoding one full GIF image per frame, rather than an animated GIF.

     Default value is 0.

global_palette INTEGER
     Writes a palette to the global GIF header where feasible.

     If disabled, every frame will always have a palette written, even if there is a global palette supplied.

     Default value is 1.

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

tile_width INTEGER
     Sets tile width. Range is 1 to 1073741824. Default is 256.

tile_height INTEGER
     Sets tile height. Range is 1 to 1073741824. Default is 256.

pred INTEGER
     Allows setting the discrete wavelet transform (DWT) type

     dwt97int (Lossy)

     dwt53 (Lossless)

     Default is dwt97int

sop BOOLEAN
     Enable this to add SOP marker at the start of each packet. Disabled by default.

eph BOOLEAN
     Enable this to add EPH marker at the end of each packet header. Disabled by default.

prog INTEGER
     Sets the progression order to be used by the encoder. Possible values are:

     lrcp

     rlcp

     rpcl

     pcrl

     cprl

     Set to lrcp by default.

layer_rates STRING
     By default, when this option is not used, compression is done using the quality metric. This option allows for compression using compression ratio. The compression ratio for each level could be specified. The compression ratio of a layer l species the what ratio of total file size is contained in the first l layers.

     Example usage:

          ffmpeg -i input.bmp -c:v jpeg2000 -layer_rates "100,10,1" output.j2k

     This would compress the image to contain 3 layers, where the data contained in the first layer would be compressed by 1000 times, compressed by 100 in the first two layers, and shall contain all data while using all 3 layers.

librav1e
========

rav1e AV1 encoder wrapper.

Requires the presence of the rav1e headers and library during configuration. You need to explicitly configure the build with --enable-librav1e.

Options
-------

qmax
     Sets the maximum quantizer to use when using bitrate mode.

qmin
     Sets the minimum quantizer to use when using bitrate mode.

qp
     Uses quantizer mode to encode at the given quantizer (0-255).

speed
     Selects the speed preset (0-10) to encode with.

tiles
     Selects how many tiles to encode with.

tile-rows
     Selects how many rows of tiles to encode with.

tile-columns
     Selects how many columns of tiles to encode with.

rav1e-params
     Set rav1e options using a list of KEY=VALUE pairs separated by ":". See rav1e --help for a list of options.

     For example to specify librav1e encoding options with -rav1e-params:

          ffmpeg -i input -c:v librav1e -b:v 500K -rav1e-params speed=5:low_latency=true output.mp4

libaom-av1
==========

libaom AV1 encoder wrapper.

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

Options
-------

The wrapper supports the following standard libavcodec options:

b
     Set bitrate target in bits/second.  By default this will use variable-bitrate mode.  If maxrate and minrate are also set to the same value then it will use constant-bitrate mode, otherwise if crf is set as well then it will use constrained-quality mode.

g keyint_min
     Set key frame placement.  The GOP size sets the maximum distance between key frames; if zero the output stream will be intra-only.  The minimum distance is ignored unless it is the same as the GOP size, in which case key frames will always appear at a fixed interval.  Not set by default, so without this option the library has completely free choice about where to place key frames.

qmin qmax
     Set minimum/maximum quantisation values.  Valid range is from 0 to 63 (warning: this does not match the quantiser values actually used by AV1 - divide by four to map real quantiser values to this range).  Defaults to min/max (no constraint).

minrate maxrate bufsize rc_init_occupancy
     Set rate control buffering parameters.  Not used if not set - defaults to unconstrained variable bitrate.

threads
     Set the number of threads to use while encoding.  This may require the tiles or row-mt options to also be set to actually use the specified number of threads fully. Defaults to the number of hardware threads supported by the host machine.

profile
     Set the encoding profile.  Defaults to using the profile which matches the bit depth and chroma subsampling of the input.

The wrapper also has some specific options:

cpu-used
     Set the quality/encoding speed tradeoff.  Valid range is from 0 to 8, higher numbers indicating greater speed and lower quality.  The default value is 1, which will be slow and high quality.

auto-alt-ref
     Enable use of alternate reference frames.  Defaults to the internal default of the library.

arnr-max-frames (frames)
     Set altref noise reduction max frame count. Default is -1.

arnr-strength (strength)
     Set altref noise reduction filter strength. Range is -1 to 6. Default is -1.

aq-mode (aq-mode)
     Set adaptive quantization mode. Possible values:

     none (0)
          Disabled.

     variance (1)
          Variance-based.

     complexity (2)
          Complexity-based.

     cyclic (3)
          Cyclic refresh.

tune (tune)
     Set the distortion metric the encoder is tuned with. Default is psnr.

     psnr (0)

     ssim (1)

lag-in-frames
     Set the maximum number of frames which the encoder may keep in flight at any one time for lookahead purposes.  Defaults to the internal default of the library.

error-resilience
     Enable error resilience features:

     default
          Improve resilience against losses of whole frames.

     Not enabled by default.

crf
     Set the quality/size tradeoff for constant-quality (no bitrate target) and constrained-quality (with maximum bitrate target) modes. Valid range is 0 to 63, higher numbers indicating lower quality and smaller output size.  Only used if set; by default only the bitrate target is used.

static-thresh
     Set a change threshold on blocks below which they will be skipped by the encoder.  Defined in arbitrary units as a nonnegative integer, defaulting to zero (no blocks are skipped).

drop-threshold
     Set a threshold for dropping frames when close to rate control bounds. Defined as a percentage of the target buffer - when the rate control buffer falls below this percentage, frames will be dropped until it has refilled above the threshold.  Defaults to zero (no frames are dropped).

denoise-noise-level (level)
     Amount of noise to be removed for grain synthesis. Grain synthesis is disabled if this option is not set or set to 0.

denoise-block-size (pixels)
     Block size used for denoising for grain synthesis. If not set, AV1 codec uses the default value of 32.

undershoot-pct (pct)
     Set datarate undershoot (min) percentage of the target bitrate. Range is -1 to 100. Default is -1.

overshoot-pct (pct)
     Set datarate overshoot (max) percentage of the target bitrate. Range is -1 to 1000. Default is -1.

minsection-pct (pct)
     Minimum percentage variation of the GOP bitrate from the target bitrate. If minsection-pct is not set, the libaomenc wrapper computes it as follows: (minrate * 100 / bitrate). Range is -1 to 100. Default is -1 (unset).

maxsection-pct (pct)
     Maximum percentage variation of the GOP bitrate from the target bitrate. If maxsection-pct is not set, the libaomenc wrapper computes it as follows: (maxrate * 100 / bitrate). Range is -1 to 5000. Default is -1 (unset).

frame-parallel (boolean)
     Enable frame parallel decodability features. Default is true.

tiles
     Set the number of tiles to encode the input video with, as columns x rows.  Larger numbers allow greater parallelism in both encoding and decoding, but may decrease coding efficiency.  Defaults to the minimum number of tiles required by the size of the input video (this is 1x1 (that is, a single tile) for sizes up to and including 4K).

tile-columns tile-rows
     Set the number of tiles as log2 of the number of tile rows and columns. Provided for compatibility with libvpx/VP9.

row-mt (Requires libaom >= 1.0.0-759-g90a15f4f2)
     Enable row based multi-threading. Disabled by default.

enable-cdef (boolean)
     Enable Constrained Directional Enhancement Filter. The libaom-av1 encoder enables CDEF by default.

enable-restoration (boolean)
     Enable Loop Restoration Filter. Default is true for libaom-av1.

enable-global-motion (boolean)
     Enable the use of global motion for block prediction. Default is true.

enable-intrabc (boolean)
     Enable block copy mode for intra block prediction. This mode is useful for screen content. Default is true.

enable-rect-partitions (boolean) (Requires libaom >= v2.0.0)
     Enable rectangular partitions. Default is true.

enable-1to4-partitions (boolean) (Requires libaom >= v2.0.0)
     Enable 1:4/4:1 partitions. Default is true.

enable-ab-partitions (boolean) (Requires libaom >= v2.0.0)
     Enable AB shape partitions. Default is true.

enable-angle-delta (boolean) (Requires libaom >= v2.0.0)
     Enable angle delta intra prediction. Default is true.

enable-cfl-intra (boolean) (Requires libaom >= v2.0.0)
     Enable chroma predicted from luma intra prediction. Default is true.

enable-filter-intra (boolean) (Requires libaom >= v2.0.0)
     Enable filter intra predictor. Default is true.

enable-intra-edge-filter (boolean) (Requires libaom >= v2.0.0)
     Enable intra edge filter. Default is true.

enable-smooth-intra (boolean) (Requires libaom >= v2.0.0)
     Enable smooth intra prediction mode. Default is true.

enable-paeth-intra (boolean) (Requires libaom >= v2.0.0)
     Enable paeth predictor in intra prediction. Default is true.

enable-palette (boolean) (Requires libaom >= v2.0.0)
     Enable palette prediction mode. Default is true.

enable-flip-idtx (boolean) (Requires libaom >= v2.0.0)
     Enable extended transform type, including FLIPADST_DCT, DCT_FLIPADST, FLIPADST_FLIPADST, ADST_FLIPADST, FLIPADST_ADST, IDTX, V_DCT, H_DCT, V_ADST, H_ADST, V_FLIPADST, H_FLIPADST. Default is true.

enable-tx64 (boolean) (Requires libaom >= v2.0.0)
     Enable 64-pt transform. Default is true.

reduced-tx-type-set (boolean) (Requires libaom >= v2.0.0)
     Use reduced set of transform types. Default is false.

use-intra-dct-only (boolean) (Requires libaom >= v2.0.0)
     Use DCT only for INTRA modes. Default is false.

use-inter-dct-only (boolean) (Requires libaom >= v2.0.0)
     Use DCT only for INTER modes. Default is false.

use-intra-default-tx-only (boolean) (Requires libaom >= v2.0.0)
     Use Default-transform only for INTRA modes. Default is false.

enable-ref-frame-mvs (boolean) (Requires libaom >= v2.0.0)
     Enable temporal mv prediction. Default is true.

enable-reduced-reference-set (boolean) (Requires libaom >= v2.0.0)
     Use reduced set of single and compound references. Default is false.

enable-obmc (boolean) (Requires libaom >= v2.0.0)
     Enable obmc. Default is true.

enable-dual-filter (boolean) (Requires libaom >= v2.0.0)
     Enable dual filter. Default is true.

enable-diff-wtd-comp (boolean) (Requires libaom >= v2.0.0)
     Enable difference-weighted compound. Default is true.

enable-dist-wtd-comp (boolean) (Requires libaom >= v2.0.0)
     Enable distance-weighted compound. Default is true.

enable-onesided-comp (boolean) (Requires libaom >= v2.0.0)
     Enable one sided compound. Default is true.

enable-interinter-wedge (boolean) (Requires libaom >= v2.0.0)
     Enable interinter wedge compound. Default is true.

enable-interintra-wedge (boolean) (Requires libaom >= v2.0.0)
     Enable interintra wedge compound. Default is true.

enable-masked-comp (boolean) (Requires libaom >= v2.0.0)
     Enable masked compound. Default is true.

enable-interintra-comp (boolean) (Requires libaom >= v2.0.0)
     Enable interintra compound. Default is true.

enable-smooth-interintra (boolean) (Requires libaom >= v2.0.0)
     Enable smooth interintra mode. Default is true.

aom-params
     Set libaom options using a list of KEY=VALUE pairs separated by ":". For a list of supported options, see aomenc --help under the section "AV1 Specific Options".

     For example to specify libaom encoding options with -aom-params:

          ffmpeg -i input -c:v libaom-av1 -b:v 500K -aom-params tune=psnr:enable-tpl-model=1 output.mp4

libsvtav1
=========

SVT-AV1 encoder wrapper.

Requires the presence of the SVT-AV1 headers and library during configuration. You need to explicitly configure the build with --enable-libsvtav1.

Options
-------

profile
     Set the encoding profile.

     main

     high

     professional

level
     Set the operating point level. For example: '4.0'

hielevel
     Set the Hierarchical prediction levels.

     3level

     4level
          This is the default.

tier
     Set the operating point tier.

     main
          This is the default.

     high

qmax
     Set the maximum quantizer to use when using a bitrate mode.

qmin
     Set the minimum quantizer to use when using a bitrate mode.

crf
     Constant rate factor value used in crf rate control mode (0-63).

qp
     Set the quantizer used in cqp rate control mode (0-63).

sc_detection
     Enable scene change detection.

la_depth
     Set number of frames to look ahead (0-120).

preset
     Set the quality-speed tradeoff, in the range 0 to 13.  Higher values are faster but lower quality.

tile_rows
     Set log2 of the number of rows of tiles to use (0-6).

tile_columns
     Set log2 of the number of columns of tiles to use (0-4).

svtav1-params
     Set SVT-AV1 options using a list of KEY=VALUE pairs separated by ":". See the SVT-AV1 encoder user guide for a list of accepted parameters.

libjxl
======

libjxl JPEG XL encoder wrapper.

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

Options
-------

The libjxl wrapper supports the following options:

distance
     Set the target Butteraugli distance. This is a quality setting: lower distance yields higher quality, with distance=1.0 roughly comparable to libjpeg Quality 90 for photographic content. Setting distance=0.0 yields true lossless encoding. Valid values range between 0.0 and 15.0, and sane values rarely exceed 5.0. Setting distance=0.1 usually attains transparency for most input. The default is 1.0.

effort
     Set the encoding effort used. Higher effort values produce more consistent quality and usually produces a better quality/bpp curve, at the cost of more CPU time required. Valid values range from 1 to 9, and the default is 7.

modular
     Force the encoder to use Modular mode instead of choosing automatically. The default is to use VarDCT for lossy encoding and Modular for lossless. VarDCT is generally superior to Modular for lossy encoding but does not support lossless encoding.

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.

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)
     Minimum (Best Quality) Quantizer.

qmax (max-q)
     Maximum (Worst Quality) Quantizer. Can be changed per-frame.

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-maxframes
          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.

     min-gf-interval
          Set minimum golden/alternate reference frame interval (VP9 only).

error-resilient
     Enable error resiliency features.

sharpness INTEGER
     Increase sharpness at the expense of lower PSNR. The valid range is [0, 7].

ts-parameters
     Sets the temporal scalability configuration using a :-separated list of key=value pairs. For example, to specify temporal scalability parameters with ffmpeg:

          ffmpeg -i INPUT -c:v libvpx -ts-parameters ts_number_layers=3:\
          ts_target_bitrate=250,500,1000:ts_rate_decimator=4,2,1:\
          ts_periodicity=4:ts_layer_id=0,2,1,2:ts_layering_mode=3 OUTPUT

     Below is a brief explanation of each of the parameters, please refer to struct vpx_codec_enc_cfg in vpx/vpx_encoder.h for more details.

     ts_number_layers
          Number of temporal coding layers.

     ts_target_bitrate
          Target bitrate for each temporal layer (in kbps). (bitrate should be inclusive of the lower temporal layer).

     ts_rate_decimator
          Frame rate decimation factor for each temporal layer.

     ts_periodicity
          Length of the sequence defining frame temporal layer membership.

     ts_layer_id
          Template defining the membership of frames to temporal layers.

     ts_layering_mode
          (optional) Selecting the temporal structure from a set of pre-defined temporal layering modes. Currently supports the following options.

          0
               No temporal layering flags are provided internally, relies on flags being passed in using metadata field in AVFrame with following keys.

               vp8-flags
                    Sets the flags passed into the encoder to indicate the referencing scheme for the current frame. Refer to function vpx_codec_encode in vpx/vpx_encoder.h for more details.

               temporal_id
                    Explicitly sets the temporal id of the current frame to encode.

          2
               Two temporal layers. 0-1...

          3
               Three temporal layers. 0-2-1-2...; with single reference frame.

          4
               Same as option "3", except there is a dependency between the two temporal layer 2 frames within the temporal period.

VP8-specific options

     screen-content-mode
          Screen content mode, one of: 0 (off), 1 (screen), 2 (screen with more aggressive rate control).

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.

     ref-frame-config
          Using per-frame metadata, set members of the structure vpx_svc_ref_frame_config_t in vpx/vp8cx.h to fine-control referencing schemes and frame buffer management.

          Use a :-separated list of key=value pairs. For example,

               av_dict_set(&av_frame->metadata, "ref-frame-config", \
               "rfc_update_buffer_slot=7:rfc_lst_fb_idx=0:rfc_gld_fb_idx=1:rfc_alt_fb_idx=2:rfc_reference_last=0:rfc_reference_golden=0:rfc_reference_alt_ref=0");

          rfc_update_buffer_slot
               Indicates the buffer slot number to update

          rfc_update_last
               Indicates whether to update the LAST frame

          rfc_update_golden
               Indicates whether to update GOLDEN frame

          rfc_update_alt_ref
               Indicates whether to update ALT_REF frame

          rfc_lst_fb_idx
               LAST frame buffer index

          rfc_gld_fb_idx
               GOLDEN frame buffer index

          rfc_alt_fb_idx
               ALT_REF frame buffer index

          rfc_reference_last
               Indicates whether to reference LAST frame

          rfc_reference_golden
               Indicates whether to reference GOLDEN frame

          rfc_reference_alt_ref
               Indicates whether to reference ALT_REF frame

          rfc_reference_duration
               Indicates frame duration

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.

-quality FLOAT
     For lossy encoding, this controls image quality. For lossless encoding, this controls the effort and time spent in compression. Range is 0 to 100. Default is 75.

-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.

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.

In the list below, note that the x264 option name is shown in parentheses after the libavcodec corresponding name, in case there is a direct mapping.

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)
     Number of B-frames between I and P-frames

g (keyint)
     Maximum GOP size

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 0-16.

level (level)
     Set the x264_param_t.i_level_idc value in case the value is positive, it is ignored otherwise.

     This value can be set using the AVCodecContext API (e.g. by setting the AVCodecContext value directly), and is specified as an integer mapped on a corresponding level (e.g. the value 31 maps to H.264 level IDC "3.1", as defined in the x264_levels table). It is ignored when set to a non positive value.

     Alternatively it can be set as a private option, overriding the value set in AVCodecContext, and in this case must be specified as the level IDC identifier (e.g. "3.1"), as defined by H.264 Annex A.

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

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

nr (nr)
     Noise reduction

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)
     Initial VBV buffer occupancy

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 values. 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 OPTS

x264-params OPTS
     Override the x264 configuration using a :-separated list of key=value options.

     The argument for both options is a list of KEY=VALUE couples separated by ":". With x264opts the value can be omitted, and the value 1 is assumed in that case.

     For FILTER and PSY-RD options values 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, the options might be provided as:

          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

     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

     To get the complete list of the libx264 options, invoke the command x264 --fullhelp or consult the libx264 documentation.

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).

udu_sei BOOLEAN
     Import user data unregistered SEI if available into output. Default is 0 (off).

mb_info BOOLEAN
     Set mb_info data through AVFrameSideData, only useful when used from the API. Default is 0 (off).

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
-------

b
     Sets target video bitrate.

bf

g
     Set the GOP size.

keyint_min
     Minimum GOP size.

refs
     Number of reference frames each P-frame can use. The range is from 1-16.

preset
     Set the x265 preset.

tune
     Set the x265 tune parameter.

profile
     Set profile restrictions.

crf
     Set the quality for constant quality mode.

qp
     Set constant quantization rate control method parameter.

qmin
     Minimum quantizer scale.

qmax
     Maximum quantizer scale.

qdiff
     Maximum difference between quantizer scales.

qblur
     Quantizer curve blur

qcomp
     Quantizer curve compression factor

i_qfactor

b_qfactor

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.

udu_sei BOOLEAN
     Import user data unregistered SEI if available into output. Default is 0 (off).

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

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.

The following standard libavcodec options are used:

  * b / bit_rate

  * g / gop_size

  * bf / max_b_frames

The encoder also has its own specific options:

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 RdoqLevel=0 output.avs2

libxeve
=======

eXtra-fast Essential Video Encoder (XEVE) MPEG-5 EVC encoder wrapper. The xeve-equivalent options or values are listed in parentheses for easy migration.

This encoder requires the presence of the libxeve headers and library during configuration. You need to explicitly configure the build with --enable-libxeve.

Many libxeve encoder options are mapped to FFmpeg global codec options, while unique encoder options are provided through private options. Additionally the xeve-params private options allows one to pass a list of key=value tuples as accepted by the libxeve parse_xeve_params function.

The xeve project website is at https://github.com/mpeg5/xeve.

Options
-------

The following options are supported by the libxeve wrapper. The xeve-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 libxeve options, invoke the command  xeve_app --help or consult the libxeve documentation.

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

bf (bframes)
     Set the maximum number of B frames (1,3,7,15).

g (keyint)
     Set the GOP size (I-picture period).

preset (preset)
     Set the xeve preset. Set the encoder preset value to determine encoding speed [fast, medium, slow, placebo]

tune (tune)
     Set the encoder tune parameter [psnr, zerolatency]

profile (profile)
     Set the encoder profile [0: baseline; 1: main]

crf (crf)
     Set the quality for constant quality mode. Constant rate factor <10..49> [default: 32]

qp (qp)
     Set constant quantization rate control method parameter. Quantization parameter qp <0..51> [default: 32]

threads (threads)
     Force to use a specific number of threads

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.

     qpel
          Enable quarter-pixel motion compensation.

     cgop
          Enable closed GOP.

     global_header
          Place global headers in extradata instead of every keyframe.

gmc
     Enable the use of global motion compensation (GMC).  Default is 0 (disabled).

me_quality
     Set motion estimation quality level. Possible values in decreasing order of speed and increasing order of quality:

     0
          Use no motion estimation (default).

     1, 2
          Enable advanced diamond zonal search for 16x16 blocks and half-pixel refinement for 16x16 blocks.

     3, 4
          Enable all of the things described above, plus advanced diamond zonal search for 8x8 blocks and half-pixel refinement for 8x8 blocks, also enable motion estimation on chroma planes for P and B-frames.

     5, 6
          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.

trellis
     Set rate-distortion optimal quantization.

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.

MediaFoundation
===============

This provides wrappers to encoders (both audio and video) in the MediaFoundation framework. It can access both SW and HW encoders. Video encoders can take input in either of nv12 or yuv420p form (some encoders support both, some support only either - in practice, nv12 is the safer choice, especially among HW encoders).

Microsoft RLE
=============

Microsoft RLE aka MSRLE encoder. Only 8-bit palette mode supported. Compatible with Windows 3.1 and Windows 95.

Options
-------

g INTEGER
     Keyframe interval. A keyframe is inserted at least every -g frames, sometimes sooner.

mpeg2
=====

MPEG-2 video encoder.

Options
-------

profile
     Select the mpeg2 profile to encode:

     422

     high

     ss
          Spatially Scalable

     snr
          SNR Scalable

     main

     simple

level
     Select the mpeg2 level to encode:

     high

     high1440

     main

     low

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.

a53cc BOOLEAN
     Import closed captions (which must be ATSC compatible format) into output. Default is 1 (on).

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, HEVC, JPEG/MJPEG, VP9, AV1)

Ratecontrol Method
------------------

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. For the ICQ modes, global quality range is 1 to 51, with 1 being the best quality.

  * Otherwise when the desired average bitrate is specified with the b option, a bitrate-based mode is used.

       - 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, both avbr_accuracy and avbr_convergence are set to non-zero. This mode is available for H264 and HEVC on Windows.

  * Otherwise the default ratecontrol method CQP is used.

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.

Global Options -> MSDK Options
------------------------------

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.

Common Options
--------------

Following options are used by all qsv encoders.

ASYNC_DEPTH
     Specifies how many asynchronous operations an application performs before the application explicitly synchronizes the result. If zero, the value is not specified.

PRESET
     This option itemizes a range of choices from veryfast (best speed) to veryslow (best quality).

     veryfast

     faster

     fast

     medium

     slow

     slower

     veryslow

FORCED_IDR
     Forcing I frames as IDR frames.

LOW_POWER
     For encoders set this flag to ON to reduce power consumption and GPU usage.

Runtime Options
---------------

Following options can be used durning qsv encoding.

GLOBAL_QUALITY

I_QUANT_FACTOR

I_QUANT_OFFSET

B_QUANT_FACTOR

B_QUANT_OFFSET
     Supported in h264_qsv and hevc_qsv. Change these value to reset qsv codec's qp configuration.

MAX_FRAME_SIZE
     Supported in h264_qsv and hevc_qsv. Change this value to reset qsv codec's MaxFrameSize configuration.

GOP_SIZE
     Change this value to reset qsv codec's gop configuration.

INT_REF_TYPE

INT_REF_CYCLE_SIZE

INT_REF_QP_DELTA

INT_REF_CYCLE_DIST
     Supported in h264_qsv and hevc_qsv. Change these value to reset qsv codec's Intra Refresh configuration.

QMAX

QMIN

MAX_QP_I

MIN_QP_I

MAX_QP_P

MIN_QP_P

MAX_QP_B

MIN_QP_B
     Supported in h264_qsv. Change these value to reset qsv codec's max/min qp configuration.

LOW_DELAY_BRC
     Supported in h264_qsv, hevc_qsv and av1_qsv. Change this value to reset qsv codec's low_delay_brc configuration.

FRAMERATE
     Change this value to reset qsv codec's framerate configuration.

BIT_RATE

RC_BUFFER_SIZE

RC_INITIAL_BUFFER_OCCUPANCY

RC_MAX_RATE
     Change these value to reset qsv codec's bitrate control configuration.

PIC_TIMING_SEI
     Supported in h264_qsv and hevc_qsv. Change this value to reset qsv codec's pic_timing_sei configuration.

H264 options
------------

These options are used by h264_qsv

EXTBRC
     Extended bitrate control.

RECOVERY_POINT_SEI
     Set this flag to insert the recovery point SEI message at the beginning of every intra refresh cycle.

RDO
     Enable rate distortion optimization.

MAX_FRAME_SIZE
     Maximum encoded frame size in bytes.

MAX_FRAME_SIZE_I
     Maximum encoded frame size for I frames in bytes. If this value is set as larger than zero, then for I frames the value set by max_frame_size is ignored.

MAX_FRAME_SIZE_P
     Maximum encoded frame size for P frames in bytes. If this value is set as larger than zero, then for P frames the value set by max_frame_size is ignored.

MAX_SLICE_SIZE
     Maximum encoded slice size in bytes.

BITRATE_LIMIT
     Toggle bitrate limitations. Modifies bitrate to be in the range imposed by the QSV encoder. Setting this flag off may lead to violation of HRD conformance. Mind that specifying bitrate below the QSV encoder range might significantly affect quality. If on this option takes effect in non CQP modes: if bitrate is not in the range imposed by the QSV encoder, it will be changed to be in the range.

MBBRC
     Setting this flag enables macroblock level bitrate control that generally improves subjective visual quality. Enabling this flag may have negative impact on performance and objective visual quality metric.

LOW_DELAY_BRC
     Setting this flag turns on or off LowDelayBRC feautre in qsv plugin, which provides more accurate bitrate control to minimize the variance of bitstream size frame by frame. Value: -1-default 0-off 1-on

ADAPTIVE_I
     This flag controls insertion of I frames by the QSV encoder. Turn ON this flag to allow changing of frame type from P and B to I.

ADAPTIVE_B
     This flag controls changing of frame type from B to P.

P_STRATEGY
     Enable P-pyramid: 0-default 1-simple 2-pyramid(bf need to be set to 0).

B_STRATEGY
     This option controls usage of B frames as reference.

DBLK_IDC
     This option disable deblocking. It has value in range 0~2.

CAVLC
     If set, CAVLC is used; if unset, CABAC is used for encoding.

VCM
     Video conferencing mode, please see ratecontrol method.

IDR_INTERVAL
     Distance (in I-frames) between IDR frames.

PIC_TIMING_SEI
     Insert picture timing SEI with pic_struct_syntax element.

SINGLE_SEI_NAL_UNIT
     Put all the SEI messages into one NALU.

MAX_DEC_FRAME_BUFFERING
     Maximum number of frames buffered in the DPB.

LOOK_AHEAD
     Use VBR algorithm with look ahead.

LOOK_AHEAD_DEPTH
     Depth of look ahead in number frames.

LOOK_AHEAD_DOWNSAMPLING
     Downscaling factor for the frames saved for the lookahead analysis.

     unknown

     auto

     off

     2x

     4x

INT_REF_TYPE
     Specifies intra refresh type. The major goal of intra refresh is improvement of error resilience without significant impact on encoded bitstream size caused by I frames. The SDK encoder achieves this by encoding part of each frame in refresh cycle using intra MBs. NONE means no refresh. VERTICAL means vertical refresh, by column of MBs. HORIZONTAL means horizontal refresh, by rows of MBs. SLICE means horizontal refresh by slices without overlapping. In case of SLICE, in_ref_cycle_size is ignored. To enable intra refresh, B frame should be set to 0.

INT_REF_CYCLE_SIZE
     Specifies number of pictures within refresh cycle starting from 2. 0 and 1 are invalid values.

INT_REF_QP_DELTA
     Specifies QP difference for inserted intra MBs. This is signed value in [-51, 51] range if target encoding bit-depth for luma samples is 8 and this range is [-63, 63] for 10 bit-depth or [-75, 75] for 12 bit-depth respectively.

INT_REF_CYCLE_DIST
     Distance between the beginnings of the intra-refresh cycles in frames.

PROFILE

     unknown

     baseline

     main

     high

A53CC
     Use A53 Closed Captions (if available).

AUD
     Insert the Access Unit Delimiter NAL.

MFMODE
     Multi-Frame Mode.

     off

     auto

REPEAT_PPS
     Repeat pps for every frame.

MAX_QP_I
     Maximum video quantizer scale for I frame.

MIN_QP_I
     Minimum video quantizer scale for I frame.

MAX_QP_P
     Maximum video quantizer scale for P frame.

MIN_QP_P
     Minimum video quantizer scale for P frame.

MAX_QP_B
     Maximum video quantizer scale for B frame.

MIN_QP_B
     Minimum video quantizer scale for B frame.

SCENARIO
     Provides a hint to encoder about the scenario for the encoding session.

     unknown

     displayremoting

     videoconference

     archive

     livestreaming

     cameracapture

     videosurveillance

     gamestreaming

     remotegaming

AVBR_ACCURACY
     Accuracy of the AVBR ratecontrol (unit of tenth of percent).

AVBR_CONVERGENCE
     Convergence of the AVBR ratecontrol (unit of 100 frames)

     The parameters AVBR_ACCURACY and AVBR_CONVERGENCE are for the average variable bitrate control (AVBR) algorithm. The algorithm focuses on overall encoding quality while meeting the specified bitrate, TARGET_BITRATE, within the accuracy range AVBR_ACCURACY, after a AVBR_CONVERGENCE period. This method does not follow HRD and the instant bitrate is not capped or padded.

SKIP_FRAME
     Use per-frame metadata "qsv_skip_frame" to skip frame when encoding. This option defines the usage of this metadata.

     no_skip
          Frame skipping is disabled.

     insert_dummy
          Encoder inserts into bitstream frame where all macroblocks are encoded as skipped.

     insert_nothing
          Similar to insert_dummy, but encoder inserts nothing into bitstream. The skipped frames are still used in brc. For example, gop still include skipped frames, and the frames after skipped frames will be larger in size.

     brc_only
          skip_frame metadata indicates the number of missed frames before the current frame.

HEVC Options
------------

These options are used by hevc_qsv

EXTBRC
     Extended bitrate control.

RECOVERY_POINT_SEI
     Set this flag to insert the recovery point SEI message at the beginning of every intra refresh cycle.

RDO
     Enable rate distortion optimization.

MAX_FRAME_SIZE
     Maximum encoded frame size in bytes.

MAX_FRAME_SIZE_I
     Maximum encoded frame size for I frames in bytes. If this value is set as larger than zero, then for I frames the value set by max_frame_size is ignored.

MAX_FRAME_SIZE_P
     Maximum encoded frame size for P frames in bytes. If this value is set as larger than zero, then for P frames the value set by max_frame_size is ignored.

MAX_SLICE_SIZE
     Maximum encoded slice size in bytes.

MBBRC
     Setting this flag enables macroblock level bitrate control that generally improves subjective visual quality. Enabling this flag may have negative impact on performance and objective visual quality metric.

LOW_DELAY_BRC
     Setting this flag turns on or off LowDelayBRC feautre in qsv plugin, which provides more accurate bitrate control to minimize the variance of bitstream size frame by frame. Value: -1-default 0-off 1-on

ADAPTIVE_I
     This flag controls insertion of I frames by the QSV encoder. Turn ON this flag to allow changing of frame type from P and B to I.

ADAPTIVE_B
     This flag controls changing of frame type from B to P.

P_STRATEGY
     Enable P-pyramid: 0-default 1-simple 2-pyramid(bf need to be set to 0).

B_STRATEGY
     This option controls usage of B frames as reference.

DBLK_IDC
     This option disable deblocking. It has value in range 0~2.

IDR_INTERVAL
     Distance (in I-frames) between IDR frames.

     begin_only
          Output an IDR-frame only at the beginning of the stream.

LOAD_PLUGIN
     A user plugin to load in an internal session.

     none

     hevc_sw

     hevc_hw

LOAD_PLUGINS
     A :-separate list of hexadecimal plugin UIDs to load in an internal session.

LOOK_AHEAD_DEPTH
     Depth of look ahead in number frames, available when extbrc option is enabled.

PROFILE
     Set the encoding profile (scc requires libmfx >= 1.32).

     unknown

     main

     main10

     mainsp

     rext

     scc

TIER
     Set the encoding tier (only level >= 4 can support high tier). This option only takes effect when the level option is specified.

     main

     high

GPB
     1: GPB (generalized P/B frame)

     0: regular P frame.

TILE_COLS
     Number of columns for tiled encoding.

TILE_ROWS
     Number of rows for tiled encoding.

AUD
     Insert the Access Unit Delimiter NAL.

PIC_TIMING_SEI
     Insert picture timing SEI with pic_struct_syntax element.

TRANSFORM_SKIP
     Turn this option ON to enable transformskip. It is supported on platform equal or newer than ICL.

INT_REF_TYPE
     Specifies intra refresh type. The major goal of intra refresh is improvement of error resilience without significant impact on encoded bitstream size caused by I frames. The SDK encoder achieves this by encoding part of each frame in refresh cycle using intra MBs. NONE means no refresh. VERTICAL means vertical refresh, by column of MBs. HORIZONTAL means horizontal refresh, by rows of MBs. SLICE means horizontal refresh by slices without overlapping. In case of SLICE, in_ref_cycle_size is ignored. To enable intra refresh, B frame should be set to 0.

INT_REF_CYCLE_SIZE
     Specifies number of pictures within refresh cycle starting from 2. 0 and 1 are invalid values.

INT_REF_QP_DELTA
     Specifies QP difference for inserted intra MBs. This is signed value in [-51, 51] range if target encoding bit-depth for luma samples is 8 and this range is [-63, 63] for 10 bit-depth or [-75, 75] for 12 bit-depth respectively.

INT_REF_CYCLE_DIST
     Distance between the beginnings of the intra-refresh cycles in frames.

MAX_QP_I
     Maximum video quantizer scale for I frame.

MIN_QP_I
     Minimum video quantizer scale for I frame.

MAX_QP_P
     Maximum video quantizer scale for P frame.

MIN_QP_P
     Minimum video quantizer scale for P frame.

MAX_QP_B
     Maximum video quantizer scale for B frame.

MIN_QP_B
     Minimum video quantizer scale for B frame.

SCENARIO
     Provides a hint to encoder about the scenario for the encoding session.

     unknown

     displayremoting

     videoconference

     archive

     livestreaming

     cameracapture

     videosurveillance

     gamestreaming

     remotegaming

AVBR_ACCURACY
     Accuracy of the AVBR ratecontrol (unit of tenth of percent).

AVBR_CONVERGENCE
     Convergence of the AVBR ratecontrol (unit of 100 frames)

     The parameters AVBR_ACCURACY and AVBR_CONVERGENCE are for the average variable bitrate control (AVBR) algorithm. The algorithm focuses on overall encoding quality while meeting the specified bitrate, TARGET_BITRATE, within the accuracy range AVBR_ACCURACY, after a AVBR_CONVERGENCE period. This method does not follow HRD and the instant bitrate is not capped or padded.

SKIP_FRAME
     Use per-frame metadata "qsv_skip_frame" to skip frame when encoding. This option defines the usage of this metadata.

     no_skip
          Frame skipping is disabled.

     insert_dummy
          Encoder inserts into bitstream frame where all macroblocks are encoded as skipped.

     insert_nothing
          Similar to insert_dummy, but encoder inserts nothing into bitstream. The skipped frames are still used in brc. For example, gop still include skipped frames, and the frames after skipped frames will be larger in size.

     brc_only
          skip_frame metadata indicates the number of missed frames before the current frame.

MPEG2 Options
-------------

These options are used by mpeg2_qsv

PROFILE

     unknown

     simple

     main

     high

VP9 Options
-----------

These options are used by vp9_qsv

PROFILE

     unknown

     profile0

     profile1

     profile2

     profile3

TILE_COLS
     Number of columns for tiled encoding (requires libmfx >= 1.29).

TILE_ROWS
     Number of rows for tiled encoding (requires libmfx  >= 1.29).

AV1 Options
-----------

These options are used by av1_qsv (requires libvpl).

PROFILE

     unknown

     main

TILE_COLS
     Number of columns for tiled encoding.

TILE_ROWS
     Number of rows for tiled encoding.

ADAPTIVE_I
     This flag controls insertion of I frames by the QSV encoder. Turn ON this flag to allow changing of frame type from P and B to I.

ADAPTIVE_B
     This flag controls changing of frame type from B to P.

B_STRATEGY
     This option controls usage of B frames as reference.

EXTBRC
     Extended bitrate control.

LOOK_AHEAD_DEPTH
     Depth of look ahead in number frames, available when extbrc option is enabled.

LOW_DELAY_BRC
     Setting this flag turns on or off LowDelayBRC feautre in qsv plugin, which provides more accurate bitrate control to minimize the variance of bitstream size frame by frame. Value: -1-default 0-off 1-on

max_frame_size
     Set the allowed max size in bytes for each frame. If the frame size exceeds the limitation, encoder will adjust the QP value to control the frame size. Invalid in CQP rate control mode.

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.

idr_interval
     Set the number of normal intra frames between full-refresh (IDR) frames in open-GOP mode.  The intra frames are still IRAPs, but will not include global headers and may have non-decodable leading pictures.

b_depth
     Set the B-frame reference depth.  When set to one (the default), all B-frames will refer only to P- or I-frames.  When set to greater values multiple layers of B-frames will be present, frames in each layer only referring to frames in higher layers.

async_depth
     Maximum processing parallelism. Increase this to improve single channel performance. This option doesn't work if driver doesn't implement vaSyncBuffer function. Please make sure there are enough hw_frames allocated if a large number of async_depth is used.

max_frame_size
     Set the allowed max size in bytes for each frame. If the frame size exceeds the limitation, encoder will adjust the QP value to control the frame size. Invalid in CQP rate control mode.

rc_mode
     Set the rate control mode to use.  A given driver may only support a subset of modes.

     Possible modes:

     auto
          Choose the mode automatically based on driver support and the other options. This is the default.

     CQP
          Constant-quality.

     CBR
          Constant-bitrate.

     VBR
          Variable-bitrate.

     ICQ
          Intelligent constant-quality.

     QVBR
          Quality-defined variable-bitrate.

     AVBR
          Average variable bitrate.

blbrc
     Enable block level rate control, which assigns different bitrate block by block. Invalid for CQP mode.

Each encoder also has its own specific options:

av1_vaapi
     profile sets the value of seq_profile. tier sets the value of seq_tier. level sets the value of seq_level_idx.

     tiles
          Set the number of tiles to encode the input video with, as columns x rows. (default is auto, which means use minimal tile column/row number).

     tile_groups
          Set tile groups number. All the tiles will be distributed as evenly as possible to each tile group. (default is 1).

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).

     tiles
          Set the number of tiles to encode the input video with, as columns x rows. Larger numbers allow greater parallelism in both encoding and decoding, but may decrease coding efficiency.

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.

vbn
===

Vizrt Binary Image encoder.

This format is used by the broadcast vendor Vizrt for quick texture streaming. Advanced features of the format such as LZW compression of texture data or generation of mipmaps are not supported.

Options
-------

format STRING
     Sets the texture compression used by the VBN file. Can be DXT1, DXT5 or RAW. Default is DXT5.

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.

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
-------

palette
     Specify the global palette used by the bitmaps.

     The format for this option is a string containing 16 24-bits hexadecimal numbers (without 0x prefix) separated by commas, for example 0d00ee, ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1, 7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c, 7c127b.

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.