av1¶

AOMedia Video 1 (AV1) decoder.

Options

operating_point

Select an operating point of a scalable AV1 bitstream (0 - 31). Default is 0.

rawvideo¶

Raw video decoder.

This decoder decodes rawvideo streams.

Options

top top_field_first

Specify the assumed field type of the input video.

libdav1d¶

dav1d AV1 decoder.

libdav1d allows libavcodec to decode the AOMedia Video 1 (AV1) codec. Requires the presence of the libdav1d headers and library during configuration. You need to explicitly configure the build with "--enable-libdav1d".

Options

The following options are supported by the libdav1d wrapper.

framethreads

Set amount of frame threads to use during decoding. The default value is 0 (autodetect). This option is deprecated for libdav1d >= 1.0 and will be removed in the future. Use the option "max_frame_delay" and the global option "threads" instead.

tilethreads

Set amount of tile threads to use during decoding. The default value is 0 (autodetect). This option is deprecated for libdav1d >= 1.0 and will be removed in the future. Use the global option "threads" instead.

max_frame_delay

Set max amount of frames the decoder may buffer internally. The default value is 0 (autodetect).

filmgrain

Apply film grain to the decoded video if present in the bitstream. Defaults to the internal default of the library. This option is deprecated and will be removed in the future. See the global option "export_side_data" to export Film Grain parameters instead of applying it.

oppoint

Select an operating point of a scalable AV1 bitstream (0 - 31). Defaults to the internal default of the library.

alllayers

Output all spatial layers of a scalable AV1 bitstream. The default value is false.

libdavs2¶

AVS2-P2/IEEE1857.4 video decoder wrapper.

This decoder allows libavcodec to decode AVS2 streams with davs2 library.

libuavs3d¶

AVS3-P2/IEEE1857.10 video decoder.

libuavs3d allows libavcodec to decode AVS3 streams. Requires the presence of the libuavs3d headers and library during configuration. You need to explicitly configure the build with "--enable-libuavs3d".

Options

The following option is supported by the libuavs3d wrapper.

frame_threads

Set amount of frame threads to use during decoding. The default value is 0 (autodetect).

libxevd¶

eXtra-fast Essential Video Decoder (XEVD) MPEG-5 EVC decoder wrapper.

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

The xevd project website is at <https://github.com/mpeg5/xevd>.

Options

The following options are supported by the libxevd wrapper. The xevd-equivalent options or values are listed in parentheses for easy migration.

To get a more accurate and extensive documentation of the libxevd options, invoke the command "xevd_app --help" or consult the libxevd documentation.

threads (threads)

Force to use a specific number of threads

QSV Decoders¶

The family of Intel QuickSync Video decoders (VC1, MPEG-2, H.264, HEVC, JPEG/MJPEG, VP8, VP9, AV1).

Common Options

The following options are supported by all qsv decoders.

async_depth

Internal parallelization depth, the higher the value the higher the latency.

gpu_copy

A GPU-accelerated copy between video and system memory

HEVC Options

Extra options for hevc_qsv.

load_plugin

A user plugin to load in an internal session

load_plugins

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

v210¶

Uncompressed 4:2:2 10-bit decoder.

Options

custom_stride

Set the line size of the v210 data in bytes. The default value is 0 (autodetect). You can use the special -1 value for a strideless v210 as seen in BOXX files.

ac3¶

AC-3 audio decoder.

This decoder implements part of ATSC A/52:2010 and ETSI TS 102 366, as well as the undocumented RealAudio 3 (a.k.a. dnet).

AC-3 Decoder Options

-drc_scale value

Dynamic Range Scale Factor. The factor to apply to dynamic range values from the AC-3 stream. This factor is applied exponentially. The default value is 1. There are 3 notable scale factor ranges:

flac¶

FLAC audio decoder.

This decoder aims to implement the complete FLAC specification from Xiph.

FLAC Decoder options

-use_buggy_lpc

The lavc FLAC encoder used to produce buggy streams with high lpc values (like the default value). This option makes it possible to decode such streams correctly by using lavc's old buggy lpc logic for decoding.

ffwavesynth¶

Internal wave synthesizer.

This decoder generates wave patterns according to predefined sequences. Its use is purely internal and the format of the data it accepts is not publicly documented.

libcelt¶

libcelt decoder wrapper.

libcelt allows libavcodec to decode the Xiph CELT ultra-low delay audio codec. Requires the presence of the libcelt headers and library during configuration. You need to explicitly configure the build with "--enable-libcelt".

libgsm¶

libgsm decoder wrapper.

libgsm allows libavcodec to decode the GSM full rate audio codec. Requires the presence of the libgsm headers and library during configuration. You need to explicitly configure the build with "--enable-libgsm".

This decoder supports both the ordinary GSM and the Microsoft variant.

libilbc¶

libilbc decoder wrapper.

libilbc allows libavcodec to decode the Internet Low Bitrate Codec (iLBC) audio codec. Requires the presence of the libilbc headers and library during configuration. You need to explicitly configure the build with "--enable-libilbc".

Options

The following option is supported by the libilbc wrapper.

enhance

Enable the enhancement of the decoded audio when set to 1. The default value is 0 (disabled).

libopencore-amrnb¶

libopencore-amrnb decoder wrapper.

libopencore-amrnb allows libavcodec to decode the Adaptive Multi-Rate Narrowband audio codec. Using it requires the presence of the libopencore-amrnb headers and library during configuration. You need to explicitly configure the build with "--enable-libopencore-amrnb".

An FFmpeg native decoder for AMR-NB exists, so users can decode AMR-NB without this library.

libopencore-amrwb¶

libopencore-amrwb decoder wrapper.

libopencore-amrwb allows libavcodec to decode the Adaptive Multi-Rate Wideband audio codec. Using it requires the presence of the libopencore-amrwb headers and library during configuration. You need to explicitly configure the build with "--enable-libopencore-amrwb".

An FFmpeg native decoder for AMR-WB exists, so users can decode AMR-WB without this library.

libopus¶

libopus decoder wrapper.

libopus allows libavcodec to decode the Opus Interactive Audio Codec. Requires the presence of the libopus headers and library during configuration. You need to explicitly configure the build with "--enable-libopus".

An FFmpeg native decoder for Opus exists, so users can decode Opus without this library.

libaribb24¶

ARIB STD-B24 caption decoder.

Implements profiles A and C of the ARIB STD-B24 standard.

libaribb24 Decoder Options

-aribb24-base-path path

Sets the base path for the libaribb24 library. This is utilized for reading of configuration files (for custom unicode conversions), and for dumping of non-text symbols as images under that location.

Unset by default.

-aribb24-skip-ruby-text boolean

Tells the decoder wrapper to skip text blocks that contain half-height ruby text.

Enabled by default.

libaribcaption¶

Yet another ARIB STD-B24 caption decoder using external libaribcaption library.

Implements profiles A and C of the Japanse ARIB STD-B24 standard, Brazilian ABNT NBR 15606-1, and Philippines version of ISDB-T.

Requires the presence of the libaribcaption headers and library (<https://github.com/xqq/libaribcaption>) during configuration. You need to explicitly configure the build with "--enable-libaribcaption". If both libaribb24 and libaribcaption are enabled, libaribcaption decoder precedes.

libaribcaption Decoder Options

-sub_type subtitle_type

Specifies the format of the decoded subtitles.

-caption_encoding encoding_scheme

Specifies the encoding scheme of input subtitle text.

-font font_name[,font_name2,...]

Specify comma-separated list of font family names to be used for bitmap or ass type subtitle rendering. Only first font name is used for ass type subtitle.

If not specified, use internaly defined default font family.

-ass_single_rect boolean

ARIB STD-B24 specifies that some captions may be displayed at different positions at a time (multi-rectangle subtitle). Since some players (e.g., old mpv) can't handle multiple ASS rectangles in a single AVSubtitle, or multiple ASS rectangles of indeterminate duration with the same start timestamp, this option can change the behavior so that all the texts are displayed in a single ASS rectangle.

The default is false.

If your player cannot handle AVSubtitles with multiple ASS rectangles properly, set this option to true or define ASS_SINGLE_RECT=1 to change default behavior at compilation.

-force_outline_text boolean

Specify whether always render outline text for all characters regardless of the indication by charactor style.

The default is false.

-outline_width number (0.0 - 3.0)

Specify width for outline text, in dots (relative).

The default is 1.5.

-ignore_background boolean

Specify whether to ignore background color rendering.

The default is false.

-ignore_ruby boolean

Specify whether to ignore rendering for ruby-like (furigana) characters.

The default is false.

-replace_drcs boolean

Specify whether to render replaced DRCS characters as Unicode characters.

The default is true.

-replace_msz_ascii boolean

Specify whether to replace MSZ (Middle Size; half width) fullwidth alphanumerics with halfwidth alphanumerics.

The default is true.

-replace_msz_japanese boolean

Specify whether to replace some MSZ (Middle Size; half width) fullwidth japanese special characters with halfwidth ones.

The default is true.

-replace_msz_glyph boolean

Specify whether to replace MSZ (Middle Size; half width) characters with halfwidth glyphs if the fonts supports it. This option works under FreeType or DirectWrite renderer with Adobe-Japan1 compliant fonts. e.g., IBM Plex Sans JP, Morisawa BIZ UDGothic, Morisawa BIZ UDMincho, Yu Gothic, Yu Mincho, and Meiryo.

The default is true.

-canvas_size image_size

Specify the resolution of the canvas to render subtitles to; usually, this should be frame size of input video. This only applies when "-subtitle_type" is set to bitmap.

The libaribcaption decoder assumes input frame size for bitmap rendering as below:

libaribcaption decoder usage examples

Display MPEG-TS file with ARIB subtitle by "ffplay" tool:

        ffplay -sub_type bitmap MPEG.TS

Display MPEG-TS file with input frame size 1920x1080 by "ffplay" tool:

        ffplay -sub_type bitmap -canvas_size 1920x1080 MPEG.TS

Embed ARIB subtitle in transcoded video:

        ffmpeg -sub_type bitmap -i src.m2t -filter_complex "[0:v][0:s]overlay" -vcodec h264 dest.mp4

dvbsub¶

Options

compute_clut

dvb_substream

Selects the dvb substream, or all substreams if -1 which is default.

dvdsub¶

This codec decodes the bitmap subtitles used in DVDs; the same subtitles can also be found in VobSub file pairs and in some Matroska files.

Options

palette

Specify the global palette used by the bitmaps. When stored in VobSub, the palette is normally specified in the index file; in Matroska, the palette is stored in the codec extra-data in the same format as in VobSub. In DVDs, the palette is stored in the IFO file, and therefore not available when reading from dumped VOB files.

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".

ifo_palette

Specify the IFO file from which the global palette is obtained. (experimental)

forced_subs_only

Only decode subtitle entries marked as forced. Some titles have forced and non-forced subtitles in the same track. Setting this flag to 1 will only keep the forced subtitles. Default value is 0.

libzvbi-teletext¶

Libzvbi allows libavcodec to decode DVB teletext pages and DVB teletext subtitles. Requires the presence of the libzvbi headers and library during configuration. You need to explicitly configure the build with "--enable-libzvbi".

Options

txt_page

List of teletext page numbers to decode. Pages that do not match the specified list are dropped. You may use the special "*" string to match all pages, or "subtitle" to match all subtitle pages. Default value is *.

txt_default_region

Set default character set used for decoding, a value between 0 and 87 (see ETS 300 706, Section 15, Table 32). Default value is -1, which does not override the libzvbi default. This option is needed for some legacy level 1.0 transmissions which cannot signal the proper charset.

txt_chop_top

Discards the top teletext line. Default value is 1.

txt_format

Specifies the format of the decoded subtitles.

txt_left

X offset of generated bitmaps, default is 0.

txt_top

Y offset of generated bitmaps, default is 0.

txt_chop_spaces

Chops leading and trailing spaces and removes empty lines from the generated text. This option is useful for teletext based subtitles where empty spaces may be present at the start or at the end of the lines or empty lines may be present between the subtitle lines because of double-sized teletext characters. Default value is 1.

txt_duration

Sets the display duration of the decoded teletext pages or subtitles in milliseconds. Default value is -1 which means infinity or until the next subtitle event comes.

txt_transparent

Force transparent background of the generated teletext bitmaps. Default value is 0 which means an opaque background.

txt_opacity

Sets the opacity (0-255) of the teletext background. If txt_transparent is not set, it only affects characters between a start box and an end box, typically subtitles. Default value is 0 if txt_transparent is set, 255 otherwise.

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:

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:

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.

*<<http://www.atsc.org/cms/standards/a_52-2010.pdf>>

*<<http://www.atsc.org/cms/standards/a_54a_with_corr_1.pdf>>

*<<http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/18_Metadata.Guide.pdf>>

*<<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.

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:

-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:

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.

Other Metadata Options

-copyright boolean

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

-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.

-original boolean

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

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.

-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.

-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.

-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.

-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.

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.

-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.

-ad_conv_type type

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

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.

-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.

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

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

ch_mode

Channel mode

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:

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:

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:

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
      

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.

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:

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:

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:

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.

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:

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:

optimize_mono

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

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":

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.

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.

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.

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

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:

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:

tune (tune)

Set the distortion metric the encoder is tuned with. Default is "psnr".

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:

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.

level

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

hielevel

Set the Hierarchical prediction levels.

tier

Set the operating point tier.

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)

quality, deadline (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

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.

VP8-specific options

VP9-specific options

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.

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:

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:

cmp

Set full pixel motion estimation comparison algorithm. Possible values:

threads (threads)

Number of encoding threads.

thread_type

Set multithreading technique. Possible values:

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:

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:

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:

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:

direct-pred (direct)

Set direct MV prediction mode. Possible values:

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:

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.

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.

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:

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:

mbd

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

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:

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:

level

Select the mpeg2 level to encode:

seq_disp_ext integer

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

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

quant_mat integer

Select quantization matrix.

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

•

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

•

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).

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.

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

a53cc

Use A53 Closed Captions (if available).

aud

Insert the Access Unit Delimiter NAL.

mfmode

Multi-Frame Mode.

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.

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.

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.

load_plugin

A user plugin to load in an internal session.

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).

tier

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

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.

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.

MPEG2 Options

These options are used by mpeg2_qsv

profile

VP9 Options

These options are used by vp9_qsv

profile

tile_cols

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

tile_rows

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