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download PDF document: ffmpeg-codecs.1.pdf

FFMPEG-CODECS(1) FFMPEG-CODECS(1)

NAME ffmpeg-codecs - FFmpeg codecs
DESCRIPTION This document describes the codecs (decoders and encoders) provided by the libavcodec library.
CODEC OPTIONS libavcodec provides some generic global options, which can be set on all the encoders and decoders. In addition each codec may support so- called private options, which are specific for a given codec.
Sometimes, a global option may only affect a specific kind of codec, and may be nonsensical or ignored by another, so you need to be aware of the meaning of the specified options. Also some options are meant only for decoding or encoding.
Options may be set by specifying -option value in the FFmpeg tools, or by setting the value explicitly in the "AVCodecContext" options or using the libavutil/opt.h API for programmatic use.
The list of supported options follow:
b integer (encoding,audio,video) Set bitrate in bits/s. Default value is 200K.
ab integer (encoding,audio) Set audio bitrate (in bits/s). Default value is 128K.
bt integer (encoding,video) Set video bitrate tolerance (in bits/s). In 1-pass mode, bitrate tolerance specifies how far ratecontrol is willing to deviate from the target average bitrate value. This is not related to min/max bitrate. Lowering tolerance too much has an adverse effect on quality.
flags flags (decoding/encoding,audio,video,subtitles) Set generic flags.
Possible values:
mv4 Use four motion vector by macroblock (mpeg4).
qpel Use 1/4 pel motion compensation.
loop Use loop filter.
qscale Use fixed qscale.
pass1 Use internal 2pass ratecontrol in first pass mode.
pass2
truncated Input bitstream might be randomly truncated.
drop_changed Don't output frames whose parameters differ from first decoded frame in stream. Error AVERROR_INPUT_CHANGED is returned when a frame is dropped.
ildct Use interlaced DCT.
low_delay Force low delay.
global_header Place global headers in extradata instead of every keyframe.
bitexact Only write platform-, build- and time-independent data. (except (I)DCT). This ensures that file and data checksums are reproducible and match between platforms. Its primary use is for regression testing.
aic Apply H263 advanced intra coding / mpeg4 ac prediction.
ilme Apply interlaced motion estimation.
cgop Use closed gop.
output_corrupt Output even potentially corrupted frames.
time_base rational number Set codec time base.
It is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented. For fixed-fps content, timebase should be "1 / frame_rate" and timestamp increments should be identically 1.
g integer (encoding,video) Set the group of picture (GOP) size. Default value is 12.
ar integer (decoding/encoding,audio) Set audio sampling rate (in Hz).
ac integer (decoding/encoding,audio) Set number of audio channels.
cutoff integer (encoding,audio) Set cutoff bandwidth. (Supported only by selected encoders, see their respective documentation sections.)
frame_size integer (encoding,audio) Set audio frame size.
Set the frame number.
delay integer qcomp float (encoding,video) Set video quantizer scale compression (VBR). It is used as a constant in the ratecontrol equation. Recommended range for default rc_eq: 0.0-1.0.
qblur float (encoding,video) Set video quantizer scale blur (VBR).
qmin integer (encoding,video) Set min video quantizer scale (VBR). Must be included between -1 and 69, default value is 2.
qmax integer (encoding,video) Set max video quantizer scale (VBR). Must be included between -1 and 1024, default value is 31.
qdiff integer (encoding,video) Set max difference between the quantizer scale (VBR).
bf integer (encoding,video) Set max number of B frames between non-B-frames.
Must be an integer between -1 and 16. 0 means that B-frames are disabled. If a value of -1 is used, it will choose an automatic value depending on the encoder.
Default value is 0.
b_qfactor float (encoding,video) Set qp factor between P and B frames.
codec_tag integer bug flags (decoding,video) Workaround not auto detected encoder bugs.
Possible values:
autodetect xvid_ilace Xvid interlacing bug (autodetected if fourcc==XVIX)
ump4 (autodetected if fourcc==UMP4)
no_padding padding bug (autodetected)
amv qpel_chroma std_qpel old standard qpel (autodetected per fourcc/version)
qpel_chroma2 direct_blocksize direct-qpel-blocksize bug (autodetected per fourcc/version)
trunc trancated frames
strict integer (decoding/encoding,audio,video) Specify how strictly to follow the standards.
Possible values:
very strictly conform to an older more strict version of the spec or reference software
strict strictly conform to all the things in the spec no matter what consequences
normal unofficial allow unofficial extensions
experimental allow non standardized experimental things, experimental (unfinished/work in progress/not well tested) decoders and encoders. Note: experimental decoders can pose a security risk, do not use this for decoding untrusted input.
b_qoffset float (encoding,video) Set QP offset between P and B frames.
err_detect flags (decoding,audio,video) Set error detection flags.
Possible values:
crccheck verify embedded CRCs
bitstream detect bitstream specification deviations
buffer detect improper bitstream length
explode abort decoding on minor error detection
ignore_err ignore decoding errors, and continue decoding. This is useful if you want to analyze the content of a video and thus want everything to be decoded no matter what. This option will not result in a video that is pleasing to watch in case of errors.
careful consider things that violate the spec and have not been seen in the wild as errors
compliant consider all spec non compliancies as errors
Set max bitrate tolerance (in bits/s). Requires bufsize to be set.
minrate integer (encoding,audio,video) Set min bitrate tolerance (in bits/s). Most useful in setting up a CBR encode. It is of little use elsewise.
bufsize integer (encoding,audio,video) Set ratecontrol buffer size (in bits).
i_qfactor float (encoding,video) Set QP factor between P and I frames.
i_qoffset float (encoding,video) Set QP offset between P and I frames.
dct integer (encoding,video) Set DCT algorithm.
Possible values:
auto autoselect a good one (default)
fastint fast integer
int accurate integer
mmx altivec faan floating point AAN DCT
lumi_mask float (encoding,video) Compress bright areas stronger than medium ones.
tcplx_mask float (encoding,video) Set temporal complexity masking.
scplx_mask float (encoding,video) Set spatial complexity masking.
p_mask float (encoding,video) Set inter masking.
dark_mask float (encoding,video) Compress dark areas stronger than medium ones.
idct integer (decoding/encoding,video) Select IDCT implementation.
Possible values:
auto int simple simplemmx simpleauto Automatically pick a IDCT compatible with the simple one
simpleneon xvid faani floating point AAN IDCT
slice_count integer ec flags (decoding,video) Set error concealment strategy.
Possible values:
guess_mvs iterative motion vector (MV) search (slow)
deblock use strong deblock filter for damaged MBs
favor_inter favor predicting from the previous frame instead of the current
bits_per_coded_sample integer aspect rational number (encoding,video) Set sample aspect ratio.
sar rational number (encoding,video) Set sample aspect ratio. Alias to aspect.
debug flags (decoding/encoding,audio,video,subtitles) Print specific debug info.
Possible values:
pict picture info
rc rate control
bitstream mb_type macroblock (MB) type
qp per-block quantization parameter (QP)
dct_coeff green_metadata display complexity metadata for the upcoming frame, GoP or for a given duration.
skip startcode er error recognition
mmco memory management control operations (H.264)
bugs buffers picture buffer allocations
Set full pel me compare function.
Possible values:
sad sum of absolute differences, fast (default)
sse sum of squared errors
satd sum of absolute Hadamard transformed differences
dct sum of absolute DCT transformed differences
psnr sum of squared quantization errors (avoid, low quality)
bit number of bits needed for the block
rd rate distortion optimal, slow
zero 0
vsad sum of absolute vertical differences
vsse sum of squared vertical differences
nsse noise preserving sum of squared differences
w53 5/3 wavelet, only used in snow
w97 9/7 wavelet, only used in snow
dctmax chroma subcmp integer (encoding,video) Set sub pel me compare function.
Possible values:
sad sum of absolute differences, fast (default)
sse sum of squared errors
satd sum of absolute Hadamard transformed differences
dct sum of absolute DCT transformed differences
psnr sum of squared quantization errors (avoid, low quality)
bit number of bits needed for the block
rd rate distortion optimal, slow
sum of squared vertical differences
nsse noise preserving sum of squared differences
w53 5/3 wavelet, only used in snow
w97 9/7 wavelet, only used in snow
dctmax chroma mbcmp integer (encoding,video) Set macroblock compare function.
Possible values:
sad sum of absolute differences, fast (default)
sse sum of squared errors
satd sum of absolute Hadamard transformed differences
dct sum of absolute DCT transformed differences
psnr sum of squared quantization errors (avoid, low quality)
bit number of bits needed for the block
rd rate distortion optimal, slow
zero 0
vsad sum of absolute vertical differences
vsse sum of squared vertical differences
nsse noise preserving sum of squared differences
w53 5/3 wavelet, only used in snow
w97 9/7 wavelet, only used in snow
dctmax chroma ildctcmp integer (encoding,video) Set interlaced dct compare function.
Possible values:
sad sum of absolute differences, fast (default)
sse sum of squared errors

bit number of bits needed for the block
rd rate distortion optimal, slow
zero 0
vsad sum of absolute vertical differences
vsse sum of squared vertical differences
nsse noise preserving sum of squared differences
w53 5/3 wavelet, only used in snow
w97 9/7 wavelet, only used in snow
dctmax chroma dia_size integer (encoding,video) Set diamond type & size for motion estimation.
(1024, INT_MAX) full motion estimation(slowest)
(768, 1024] umh motion estimation
(512, 768] hex motion estimation
(256, 512] l2s diamond motion estimation
[2,256] var diamond motion estimation
(-1, 2) small diamond motion estimation
-1 funny diamond motion estimation
(INT_MIN, -1) sab diamond motion estimation
last_pred integer (encoding,video) Set amount of motion predictors from the previous frame.
precmp integer (encoding,video) Set pre motion estimation compare function.
Possible values:
sad sum of absolute differences, fast (default)
psnr sum of squared quantization errors (avoid, low quality)
bit number of bits needed for the block
rd rate distortion optimal, slow
zero 0
vsad sum of absolute vertical differences
vsse sum of squared vertical differences
nsse noise preserving sum of squared differences
w53 5/3 wavelet, only used in snow
w97 9/7 wavelet, only used in snow
dctmax chroma pre_dia_size integer (encoding,video) Set diamond type & size for motion estimation pre-pass.
subq integer (encoding,video) Set sub pel motion estimation quality.
me_range integer (encoding,video) Set limit motion vectors range (1023 for DivX player).
global_quality integer (encoding,audio,video) slice_flags integer mbd integer (encoding,video) Set macroblock decision algorithm (high quality mode).
Possible values:
simple use mbcmp (default)
bits use fewest bits
rd use best rate distortion
rc_init_occupancy integer (encoding,video) Set number of bits which should be loaded into the rc buffer before decoding starts.
flags2 flags (decoding/encoding,audio,video,subtitles) Possible values:
fast Allow non spec compliant speedup tricks.
Place global headers at every keyframe instead of in extradata.
chunks Frame data might be split into multiple chunks.
showall Show all frames before the first keyframe.
export_mvs Export motion vectors into frame side-data (see "AV_FRAME_DATA_MOTION_VECTORS") for codecs that support it. See also doc/examples/export_mvs.c.
skip_manual Do not skip samples and export skip information as frame side data.
ass_ro_flush_noop Do not reset ASS ReadOrder field on flush.
icc_profiles Generate/parse embedded ICC profiles from/to colorimetry tags.
export_side_data flags (decoding/encoding,audio,video,subtitles) Possible values:
mvs Export motion vectors into frame side-data (see "AV_FRAME_DATA_MOTION_VECTORS") for codecs that support it. See also doc/examples/export_mvs.c.
prft Export encoder Producer Reference Time into packet side-data (see "AV_PKT_DATA_PRFT") for codecs that support it.
venc_params Export video encoding parameters through frame side data (see "AV_FRAME_DATA_VIDEO_ENC_PARAMS") for codecs that support it. At present, those are H.264 and VP9.
film_grain Export film grain parameters through frame side data (see "AV_FRAME_DATA_FILM_GRAIN_PARAMS"). Supported at present by AV1 decoders.
threads integer (decoding/encoding,video) Set the number of threads to be used, in case the selected codec implementation supports multi-threading.
Possible values:
auto, 0 automatically select the number of threads to set
Default value is auto.
dc integer (encoding,video) Set intra_dc_precision.
nssew integer (encoding,video)
profile integer (encoding,audio,video) Set encoder codec profile. Default value is unknown. Encoder specific profiles are documented in the relevant encoder documentation.
level integer (encoding,audio,video) Possible values:
unknown lowres integer (decoding,audio,video) Decode at 1= 1/2, 2=1/4, 3=1/8 resolutions.
mblmin integer (encoding,video) Set min macroblock lagrange factor (VBR).
mblmax integer (encoding,video) Set max macroblock lagrange factor (VBR).
skip_loop_filter integer (decoding,video) skip_idct integer (decoding,video) skip_frame integer (decoding,video) Make decoder discard processing depending on the frame type selected by the option value.
skip_loop_filter skips frame loop filtering, skip_idct skips frame IDCT/dequantization, skip_frame skips decoding.
Possible values:
none Discard no frame.
default Discard useless frames like 0-sized frames.
noref Discard all non-reference frames.
bidir Discard all bidirectional frames.
nokey Discard all frames excepts keyframes.
nointra Discard all frames except I frames.
all Discard all frames.
Default value is default.
bidir_refine integer (encoding,video) Refine the two motion vectors used in bidirectional macroblocks.
keyint_min integer (encoding,video) Set minimum interval between IDR-frames.
refs integer (encoding,video) bits_per_raw_sample integer channel_layout integer (decoding/encoding,audio) Possible values:
request_channel_layout integer (decoding,audio) Possible values:
rc_max_vbv_use float (encoding,video) rc_min_vbv_use float (encoding,video) ticks_per_frame integer (decoding/encoding,audio,video) color_primaries integer (decoding/encoding,video) Possible values:
bt709 BT.709
bt470m BT.470 M
bt470bg BT.470 BG
smpte170m SMPTE 170 M
smpte240m SMPTE 240 M
film Film
bt2020 BT.2020
smpte428 smpte428_1 SMPTE ST 428-1
smpte431 SMPTE 431-2
smpte432 SMPTE 432-1
jedec-p22 JEDEC P22
color_trc integer (decoding/encoding,video) Possible values:
bt709 BT.709
gamma22 BT.470 M
gamma28 BT.470 BG
Linear
log log100 Log
log_sqrt log316 Log square root
iec61966_2_4 iec61966-2-4 IEC 61966-2-4
bt1361 bt1361e BT.1361
iec61966_2_1 iec61966-2-1 IEC 61966-2-1
bt2020_10 bt2020_10bit BT.2020 - 10 bit
bt2020_12 bt2020_12bit BT.2020 - 12 bit
smpte2084 SMPTE ST 2084
smpte428 smpte428_1 SMPTE ST 428-1
arib-std-b67 ARIB STD-B67
colorspace integer (decoding/encoding,video) Possible values:
rgb RGB
bt709 BT.709
fcc FCC
bt470bg BT.470 BG
smpte170m SMPTE 170 M
smpte240m SMPTE 240 M
bt2020c bt2020_cl BT.2020 CL
smpte2085 SMPTE 2085
chroma-derived-nc Chroma-derived NCL
chroma-derived-c Chroma-derived CL
ictcp ICtCp
color_range integer (decoding/encoding,video) If used as input parameter, it serves as a hint to the decoder, which color_range the input has. Possible values:
tv mpeg MPEG (219*2^(n-8))
pc jpeg JPEG (2^n-1)
chroma_sample_location integer (decoding/encoding,video) Possible values:
left center topleft top bottomleft bottom log_level_offset integer Set the log level offset.
slices integer (encoding,video) Number of slices, used in parallelized encoding.
thread_type flags (decoding/encoding,video) Select which multithreading methods to use.
Use of frame will increase decoding delay by one frame per thread, so clients which cannot provide future frames should not use it.
Possible values:
slice Decode more than one part of a single frame at once.
Multithreading using slices works only when the video was encoded with slices.
frame Decode more than one frame at once.
ma Main Audio Service
ef Effects
vi Visually Impaired
hi Hearing Impaired
di Dialogue
co Commentary
em Emergency
vo Voice Over
ka Karaoke
request_sample_fmt sample_fmt (decoding,audio) Set sample format audio decoders should prefer. Default value is "none".
pkt_timebase rational number sub_charenc encoding (decoding,subtitles) Set the input subtitles character encoding.
field_order field_order (video) Set/override the field order of the video. Possible values:
progressive Progressive video
tt Interlaced video, top field coded and displayed first
bb Interlaced video, bottom field coded and displayed first
tb Interlaced video, top coded first, bottom displayed first
bt Interlaced video, bottom coded first, top displayed first
skip_alpha bool (decoding,video) Set to 1 to disable processing alpha (transparency). This works like the gray flag in the flags option which skips chroma information instead of alpha. Default is 0.
codec_whitelist list (input) "," separated list of allowed decoders. By default all are allowed.
dump_separator string (input) Separator used to separate the fields printed on the command line about the Stream parameters. For example, to separate the fields with newlines and indentation:
ffprobe -dump_separator " " -i ~/videos/matrixbench_mpeg2.mpg
max_pixels integer (decoding/encoding,video) Maximum number of pixels per image. This value can be used to avoid alignment depends on if "AV_CODEC_FLAG_UNALIGNED" is set and the CPU. "AV_CODEC_FLAG_UNALIGNED" cannot be changed from the command line. Also hardware decoders will not apply left/top Cropping.
DECODERS Decoders are configured elements in FFmpeg which allow the decoding of multimedia streams.
When you configure your FFmpeg build, all the supported native decoders are enabled by default. Decoders requiring an external library must be enabled manually via the corresponding "--enable-lib" option. You can list all available decoders using the configure option "--list-decoders".
You can disable all the decoders with the configure option "--disable-decoders" and selectively enable / disable single decoders with the options "--enable-decoder=DECODER" / "--disable-decoder=DECODER".
The option "-decoders" of the ff* tools will display the list of enabled decoders.
VIDEO DECODERS A description of some of the currently available video decoders follows.
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.
-1 the video is assumed to be progressive (default)
0 bottom-field-first is assumed
1 top-field-first is assumed
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".
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).
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 off
HEVC Options
Extra options for hevc_qsv.
load_plugin A user plugin to load in an internal session
none hevc_sw hevc_hw load_plugins A :-separate list of hexadecimal plugin UIDs to load in an internal session
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.
AUDIO DECODERS A description of some of the currently available audio decoders follows.
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:
drc_scale == 0 DRC disabled. Produces full range audio.
0 < drc_scale <= 1 DRC enabled. Applies a fraction of the stream DRC value. Audio reproduction is between full range and full compression.
drc_scale > 1 DRC enabled. Applies drc_scale asymmetrically. Loud sounds are fully compressed. Soft sounds are enhanced.
flac FLAC audio decoder.
This decoder aims to implement the complete FLAC specification from Xiph. 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 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.
SUBTITLES DECODERS 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.
dvbsub Options
compute_clut -2 Compute clut once if no matching CLUT is in the stream.
-1 Compute clut if no matching CLUT is in the stream.
0 Never compute CLUT
1 Always compute CLUT and override the one provided in the stream.
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 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.
bitmap The default format, you should use this for teletext pages, because certain graphics and colors cannot be expressed in simple text or even ASS.
text Simple text based output without formatting.
ass Formatted ASS output, subtitle pages and teletext pages are returned in different styles, subtitle pages are stripped down to text, but an effort is made to keep the text alignment and the formatting.
txt_left X offset of generated bitmaps, default is 0.
txt_top Y offset of generated bitmaps, default is 0.
txt_chop_spaces 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.
ENCODERS Encoders are configured elements in FFmpeg which allow the encoding of multimedia streams.
When you configure your FFmpeg build, all the supported native encoders are enabled by default. Encoders requiring an external library must be enabled manually via the corresponding "--enable-lib" option. You can list all available encoders using the configure option "--list-encoders".
You can disable all the encoders with the configure option "--disable-encoders" and selectively enable / disable single encoders with the options "--enable-encoder=ENCODER" / "--disable-encoder=ENCODER".
The option "-encoders" of the ff* tools will display the list of enabled encoders.
AUDIO ENCODERS A description of some of the currently available audio encoders follows.
aac Advanced Audio Coding (AAC) encoder.
This encoder is the default AAC encoder, natively implemented into FFmpeg.
Options
b Set bit rate in bits/s. Setting this automatically activates constant bit rate (CBR) mode. If this option is unspecified it is set to 128kbps.
q Set quality for variable bit rate (VBR) mode. This option is valid only using the ffmpeg command-line tool. For library interface users, use global_quality.
cutoff Set cutoff frequency. If unspecified will allow the encoder to dynamically adjust the cutoff to improve clarity on low bitrates.
aac_coder Set AAC encoder coding method. Possible values:
whether aac_is, aac_ms and aac_pns are enabled.
anmr Average noise to mask ratio (ANMR) trellis-based solution.
This is an experimental coder which currently produces a lower quality, is more unstable and is slower than the default twoloop coder but has potential. Currently has no support for the aac_is or aac_pns options. Not currently recommended.
fast Constant quantizer method.
Uses a cheaper version of twoloop algorithm that doesn't try to do as many clever adjustments. Worse with low bitrates (less than 64kbps), but is better and much faster at higher bitrates.
aac_ms Sets mid/side coding mode. The default value of "auto" will automatically use M/S with bands which will benefit from such coding. Can be forced for all bands using the value "enable", which is mainly useful for debugging or disabled using "disable".
aac_is Sets intensity stereo coding tool usage. By default, it's enabled and will automatically toggle IS for similar pairs of stereo bands if it's beneficial. Can be disabled for debugging by setting the value to "disable".
aac_pns Uses perceptual noise substitution to replace low entropy high frequency bands with imperceptible white noise during the decoding process. By default, it's enabled, but can be disabled for debugging purposes by using "disable".
aac_tns Enables the use of a multitap FIR filter which spans through the high frequency bands to hide quantization noise during the encoding process and is reverted by the decoder. As well as decreasing unpleasant artifacts in the high range this also reduces the entropy in the high bands and allows for more bits to be used by the mid-low bands. By default it's enabled but can be disabled for debugging by setting the option to "disable".
aac_ltp Enables the use of the long term prediction extension which increases coding efficiency in very low bandwidth situations such as encoding of voice or solo piano music by extending constant harmonic peaks in bands throughout frames. This option is implied by profile:a aac_low and is incompatible with aac_pred. Use in conjunction with -ar to decrease the samplerate.
aac_pred Enables the use of a more traditional style of prediction where the spectral coefficients transmitted are replaced by the difference of the current coefficients minus the previous "predicted" coefficients. In theory and sometimes in practice this can improve quality for low to mid bitrate audio. This option implies the aac_main profile and is incompatible with aac_ltp.
mpeg2_aac_low Equivalent to "-profile:a aac_low -aac_pns 0". PNS was introduced with the MPEG4 specifications.
aac_ltp Long term prediction profile, is enabled by and will enable the aac_ltp option. Introduced in MPEG4.
aac_main Main-type prediction profile, is enabled by and will enable the aac_pred option. Introduced in MPEG2.
If this option is unspecified it is set to aac_low.
ac3 and ac3_fixed AC-3 audio encoders.
These encoders implement part of ATSC A/52:2010 and ETSI TS 102 366, as well as the undocumented RealAudio 3 (a.k.a. dnet).
The ac3 encoder uses floating-point math, while the ac3_fixed encoder only uses fixed-point integer math. This does not mean that one is always faster, just that one or the other may be better suited to a particular system. The ac3_fixed encoder is not the default codec for any of the output formats, so it must be specified explicitly using the option "-acodec ac3_fixed" in order to use it.
AC-3 Metadata
The AC-3 metadata options are used to set parameters that describe the audio, but in most cases do not affect the audio encoding itself. Some of the options do directly affect or influence the decoding and playback of the resulting bitstream, while others are just for informational purposes. A few of the options will add bits to the output stream that could otherwise be used for audio data, and will thus affect the quality of the output. Those will be indicated accordingly with a note in the option list below.
These parameters are described in detail in several publicly-available documents.
*<<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.
0 The metadata values set at initialization will be used for every frame in the stream. (default)
1 Metadata values can be changed before encoding each frame.
Downmix Levels 0.707 Apply -3dB gain
0.595 Apply -4.5dB gain (default)
0.500 Apply -6dB gain
-surround_mixlev level Surround Mix Level. The amount of gain the decoder should apply to the surround channel(s) when downmixing to stereo. This field will only be written to the bitstream if one or more surround channels are present. The value is specified as a scale factor. There are 3 valid values:
0.707 Apply -3dB gain
0.500 Apply -6dB gain (default)
0.000 Silence Surround Channel(s)
Audio Production Information
Audio Production Information is optional information describing the mixing environment. Either none or both of the fields are written to the bitstream.
-mixing_level number Mixing Level. Specifies peak sound pressure level (SPL) in the production environment when the mix was mastered. Valid values are 80 to 111, or -1 for unknown or not indicated. The default value is -1, but that value cannot be used if the Audio Production Information is written to the bitstream. Therefore, if the "room_type" option is not the default value, the "mixing_level" option must not be -1.
-room_type type Room Type. Describes the equalization used during the final mixing session at the studio or on the dubbing stage. A large room is a dubbing stage with the industry standard X-curve equalization; a small room has flat equalization. This field will not be written to the bitstream if both the "mixing_level" option and the "room_type" option have the default values.
0 notindicated Not Indicated (default)
1 large Large Room
2 small Small Room
0 off No Copyright Exists (default)
1 on Copyright Exists
-dialnorm value Dialogue Normalization. Indicates how far the average dialogue level of the program is below digital 100% full scale (0 dBFS). This parameter determines a level shift during audio reproduction that sets the average volume of the dialogue to a preset level. The goal is to match volume level between program sources. A value of -31dB will result in no volume level change, relative to the source volume, during audio reproduction. Valid values are whole numbers in the range -31 to -1, with -31 being the default.
-dsur_mode mode Dolby Surround Mode. Specifies whether the stereo signal uses Dolby Surround (Pro Logic). This field will only be written to the bitstream if the audio stream is stereo. Using this option does NOT mean the encoder will actually apply Dolby Surround processing.
0 notindicated Not Indicated (default)
1 off Not Dolby Surround Encoded
2 on Dolby Surround Encoded
-original boolean Original Bit Stream Indicator. Specifies whether this audio is from the original source and not a copy.
0 off Not Original Source
1 on Original Source (default)
Extended Bitstream Information
The extended bitstream options are part of the Alternate Bit Stream Syntax as specified in Annex D of the A/52:2010 standard. It is grouped into 2 parts. If any one parameter in a group is specified, all values in that group will be written to the bitstream. Default values are used for those that are written but have not been specified. If the mixing levels are written, the decoder will use these values instead of the ones specified in the "center_mixlev" and "surround_mixlev" options if it supports the Alternate Bit Stream Syntax.
Extended Bitstream Information - Part 1
-dmix_mode mode Preferred Stereo Downmix Mode. Allows the user to select either Lt/Rt (Dolby Surround) or Lo/Ro (normal stereo) as the preferred stereo downmix mode. Lt/Rt Downmix Preferred
2 loro Lo/Ro Downmix Preferred
-ltrt_cmixlev level Lt/Rt Center Mix Level. The amount of gain the decoder should apply to the center channel when downmixing to stereo in Lt/Rt mode.
1.414 Apply +3dB gain
1.189 Apply +1.5dB gain
1.000 Apply 0dB gain
0.841 Apply -1.5dB gain
0.707 Apply -3.0dB gain
0.595 Apply -4.5dB gain (default)
0.500 Apply -6.0dB gain
0.000 Silence Center Channel
-ltrt_surmixlev level Lt/Rt Surround Mix Level. The amount of gain the decoder should apply to the surround channel(s) when downmixing to stereo in Lt/Rt mode.
0.841 Apply -1.5dB gain
0.707 Apply -3.0dB gain
0.595 Apply -4.5dB gain
0.500 Apply -6.0dB gain (default)
0.000 Silence Surround Channel(s)
-loro_cmixlev level Lo/Ro Center Mix Level. The amount of gain the decoder should apply to the center channel when downmixing to stereo in Lo/Ro mode.
1.414
0.841 Apply -1.5dB gain
0.707 Apply -3.0dB gain
0.595 Apply -4.5dB gain (default)
0.500 Apply -6.0dB gain
0.000 Silence Center Channel
-loro_surmixlev level Lo/Ro Surround Mix Level. The amount of gain the decoder should apply to the surround channel(s) when downmixing to stereo in Lo/Ro mode.
0.841 Apply -1.5dB gain
0.707 Apply -3.0dB gain
0.595 Apply -4.5dB gain
0.500 Apply -6.0dB gain (default)
0.000 Silence Surround Channel(s)
Extended Bitstream Information - Part 2
-dsurex_mode mode Dolby Surround EX Mode. Indicates whether the stream uses Dolby Surround EX (7.1 matrixed to 5.1). Using this option does NOT mean the encoder will actually apply Dolby Surround EX processing.
0 notindicated Not Indicated (default)
1 on Dolby Surround EX Off
2 off Dolby Surround EX On
-dheadphone_mode mode Dolby Headphone Mode. Indicates whether the stream uses Dolby Headphone encoding (multi-channel matrixed to 2.0 for use with headphones). Using this option does NOT mean the encoder will actually apply Dolby Headphone processing.
2 off Dolby Headphone On
-ad_conv_type type A/D Converter Type. Indicates whether the audio has passed through HDCD A/D conversion.
0 standard Standard A/D Converter (default)
1 hdcd HDCD A/D Converter
Other AC-3 Encoding Options
-stereo_rematrixing boolean Stereo Rematrixing. Enables/Disables use of rematrixing for stereo input. This is an optional AC-3 feature that increases quality by selectively encoding the left/right channels as mid/side. This option is enabled by default, and it is highly recommended that it be left as enabled except for testing purposes.
cutoff frequency Set lowpass cutoff frequency. If unspecified, the encoder selects a default determined by various other encoding parameters.
Floating-Point-Only AC-3 Encoding Options
These options are only valid for the floating-point encoder and do not exist for the fixed-point encoder due to the corresponding features not being implemented in fixed-point.
-channel_coupling boolean Enables/Disables use of channel coupling, which is an optional AC-3 feature that increases quality by combining high frequency information from multiple channels into a single channel. The per- channel high frequency information is sent with less accuracy in both the frequency and time domains. This allows more bits to be used for lower frequencies while preserving enough information to reconstruct the high frequencies. This option is enabled by default for the floating-point encoder and should generally be left as enabled except for testing purposes or to increase encoding speed.
-1 auto Selected by Encoder (default)
0 off Disable Channel Coupling
1 on Enable Channel Coupling
-cpl_start_band number Coupling Start Band. Sets the channel coupling start band, from 1 to 15. If a value higher than the bandwidth is used, it will be reduced to 1 less than the coupling end band. If auto is used, the
flac FLAC (Free Lossless Audio Codec) Encoder
Options
The following options are supported by FFmpeg's flac encoder.
compression_level Sets the compression level, which chooses defaults for many other options if they are not set explicitly. Valid values are from 0 to 12, 5 is the default.
frame_size Sets the size of the frames in samples per channel.
lpc_coeff_precision Sets the LPC coefficient precision, valid values are from 1 to 15, 15 is the default.
lpc_type Sets the first stage LPC algorithm
none LPC is not used
fixed fixed LPC coefficients
levinson cholesky lpc_passes Number of passes to use for Cholesky factorization during LPC analysis
min_partition_order The minimum partition order
max_partition_order The maximum partition order
prediction_order_method estimation 2level 4level 8level search Bruteforce search
log ch_mode Channel mode
auto The mode is chosen automatically for each frame
indep Channels are independently coded

multi_dim_quant Multi Dimensional Quantization. If set to 1 then a 2nd stage LPC algorithm is applied after the first stage to finetune the coefficients. This is quite slow and slightly improves compression.
opus Opus encoder.
This is a native FFmpeg encoder for the Opus format. Currently its in development and only implements the CELT part of the codec. Its quality is usually worse and at best is equal to the libopus encoder.
Options
b Set bit rate in bits/s. If unspecified it uses the number of channels and the layout to make a good guess.
opus_delay Sets the maximum delay in milliseconds. Lower delays than 20ms will very quickly decrease quality.
libfdk_aac libfdk-aac AAC (Advanced Audio Coding) encoder wrapper.
The libfdk-aac library is based on the Fraunhofer FDK AAC code from the Android project.
Requires the presence of the libfdk-aac headers and library during configuration. You need to explicitly configure the build with "--enable-libfdk-aac". The library is also incompatible with GPL, so if you allow the use of GPL, you should configure with "--enable-gpl --enable-nonfree --enable-libfdk-aac".
This encoder 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. will use a value automatically computed by the library. Default value is 0.
profile Set audio profile.
The following profiles are recognized:
aac_low Low Complexity AAC (LC)
aac_he High Efficiency AAC (HE-AAC)
aac_he_v2 High Efficiency AAC version 2 (HE-AACv2)
aac_ld Low Delay AAC (LD)
aac_eld Enhanced Low Delay AAC (ELD)
If not specified it is set to aac_low.
The following are private options of the libfdk_aac encoder.
afterburner Enable afterburner feature if set to 1, disabled if set to 0. This improves the quality but also the required processing power.
Default value is 1.
eld_sbr Enable SBR (Spectral Band Replication) for ELD if set to 1, disabled if set to 0.
Default value is 0.
eld_v2 Enable ELDv2 (LD-MPS extension for ELD stereo signals) for ELDv2 if set to 1, disabled if set to 0.
Note that option is available when fdk-aac version (AACENCODER_LIB_VL0.AACENCODER_LIB_VL1.AACENCODER_LIB_VL2) > (4.0.0).
Default value is 0.
signaling Set SBR/PS signaling style.
It can assume one of the following values:
default choose signaling implicitly (explicit hierarchical by default, implicit if global header is disabled)
implicit
Default value is default.
latm Output LATM/LOAS encapsulated data if set to 1, disabled if set to 0.
Default value is 0.
header_period Set StreamMuxConfig and PCE repetition period (in frames) for sending in-band configuration buffers within LATM/LOAS transport layer.
Must be a 16-bits non-negative integer.
Default value is 0.
vbr Set VBR mode, from 1 to 5. 1 is lowest quality (though still pretty good) and 5 is highest quality. A value of 0 will disable VBR, and CBR (Constant Bit Rate) is enabled.
Currently only the aac_low profile supports VBR encoding.
VBR modes 1-5 correspond to roughly the following average bit rates:
1 32 kbps/channel
2 40 kbps/channel
3 48-56 kbps/channel
4 64 kbps/channel
5 about 80-96 kbps/channel
Default value is 0.
Examples
o 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
o 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 b (-b) Set bitrate expressed in bits/s for CBR or ABR. LAME "bitrate" is expressed in kilobits/s.
q (-V) Set constant quality setting for VBR. This option is valid only using the ffmpeg command-line tool. For library interface users, use global_quality.
compression_level (-q) Set algorithm quality. Valid arguments are integers in the 0-9 range, with 0 meaning highest quality but slowest, and 9 meaning fastest while producing the worst quality.
cutoff (--lowpass) Set lowpass cutoff frequency. If unspecified, the encoder dynamically adjusts the cutoff.
reservoir Enable use of bit reservoir when set to 1. Default value is 1. LAME has this enabled by default, but can be overridden by use --nores option.
joint_stereo (-m j) Enable the encoder to use (on a frame by frame basis) either L/R stereo or mid/side stereo. Default value is 1.
abr (--abr) Enable the encoder to use ABR when set to 1. The lame --abr sets the target bitrate, while this options only tells FFmpeg to use ABR still relies on b to set bitrate.
libopencore-amrnb OpenCORE Adaptive Multi-Rate Narrowband encoder.
Requires the presence of the libopencore-amrnb headers and library during configuration. You need to explicitly configure the build with "--enable-libopencore-amrnb --enable-version3".
This is a mono-only encoder. Officially it only supports 8000Hz sample rate, but you can override it by setting strict to unofficial or lower.
Options
b Set bitrate in bits per second. Only the following bitrates are supported, otherwise libavcodec will round to the nearest valid bitrate.
4750 5150 5900 6700 7400 7950 10200 12200 dtx Allow discontinuous transmission (generate comfort noise) when set to 1. The default value is 0 (disabled).
Option Mapping
Most libopus options are modelled after the opusenc utility from opus- tools. The following is an option mapping chart describing options supported by the libopus wrapper, and their opusenc-equivalent in parentheses.
b (bitrate) Set the bit rate in bits/s. FFmpeg's b option is expressed in bits/s, while opusenc's bitrate in kilobits/s.
vbr (vbr, hard-cbr, and cvbr) Set VBR mode. The FFmpeg vbr option has the following valid arguments, with the opusenc equivalent options in parentheses:
off (hard-cbr) Use constant bit rate encoding.
on (vbr) Use variable bit rate encoding (the default).
constrained (cvbr) Use constrained variable bit rate encoding.
compression_level (comp) Set encoding algorithm complexity. Valid options are integers in the 0-10 range. 0 gives the fastest encodes but lower quality, while 10 gives the highest quality but slowest encoding. The default is 10.
frame_duration (framesize) Set maximum frame size, or duration of a frame in milliseconds. The argument must be exactly the following: 2.5, 5, 10, 20, 40, 60. Smaller frame sizes achieve lower latency but less quality at a given bitrate. Sizes greater than 20ms are only interesting at fairly low bitrates. The default is 20ms.
packet_loss (expect-loss) Set expected packet loss percentage. The default is 0.
fec (n/a) Enable inband forward error correction. packet_loss must be non- zero to take advantage - frequency of FEC 'side-data' is proportional to expected packet loss. Default is disabled.
application (N.A.) Set intended application type. Valid options are listed below:
voip Favor improved speech intelligibility.
audio Favor faithfulness to the input (the default).
lowdelay Restrict to only the lowest delay modes.
cutoff (N.A.) Set cutoff bandwidth in Hz. The argument must be exactly one of the 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 Set quality for experimental VBR support. Maximum value range is from -50 to 50, useful range is from -10 to 10. The higher the value, the better the quality. This option is valid only using the ffmpeg command-line tool. For library interface users, use global_quality.
mode (--mode) Set the mode of the resulting audio. Possible values:
auto Choose mode automatically based on the input. This is the default.
stereo Stereo
joint_stereo Joint stereo
dual_channel Dual channel
mono Mono
psymodel (--psyc-mode) Set psychoacoustic model to use in encoding. The argument must be an integer between -1 and 4, inclusive. The higher the value, the better the quality. The default value is 3.
energy_levels (--energy) Enable energy levels extensions when set to 1. The default value is 0 (disabled).
error_protection (--protect) Enable CRC error protection when set to 1. The default value is 0 (disabled).
copyright (--copyright) Set MPEG audio copyright flag when set to 1. The default value is 0 (disabled).
original (--original) Set MPEG audio original flag when set to 1. The default value is 0 (disabled).
libvo-amrwbenc VisualOn Adaptive Multi-Rate Wideband encoder.
Requires the presence of the libvo-amrwbenc headers and library during configuration. You need to explicitly configure the build with "--enable-libvo-amrwbenc --enable-version3".
This is a mono-only encoder. Officially it only supports 16000Hz sample rate, but you can override it by setting strict to unofficial or lower.
Options
b Set bitrate in bits/s. Only the following bitrates are supported, 18250 19850 23050 23850 dtx Allow discontinuous transmission (generate comfort noise) when set to 1. The default value is 0 (disabled).
libvorbis libvorbis encoder wrapper.
Requires the presence of the libvorbisenc headers and library during configuration. You need to explicitly configure the build with "--enable-libvorbis".
Options
The following options are supported by the libvorbis wrapper. The oggenc-equivalent of the options are listed in parentheses.
To get a more accurate and extensive documentation of the libvorbis options, consult the libvorbisenc's and oggenc's documentations. See <http://xiph.org/vorbis/>, <http://wiki.xiph.org/Vorbis-tools>, and oggenc(1).
b (-b) Set bitrate expressed in bits/s for ABR. oggenc -b is expressed in kilobits/s.
q (-q) Set constant quality setting for VBR. The value should be a float number in the range of -1.0 to 10.0. The higher the value, the better the quality. The default value is 3.0.
This option is valid only using the ffmpeg command-line tool. For library interface users, use global_quality.
cutoff (--advanced-encode-option lowpass_frequency=N) Set cutoff bandwidth in Hz, a value of 0 disables cutoff. oggenc's related option is expressed in kHz. The default value is 0 (cutoff disabled).
minrate (-m) Set minimum bitrate expressed in bits/s. oggenc -m is expressed in kilobits/s.
maxrate (-M) Set maximum bitrate expressed in bits/s. oggenc -M is expressed in kilobits/s. This only has effect on ABR mode.
iblock (--advanced-encode-option impulse_noisetune=N) Set noise floor bias for impulse blocks. The value is a float number from -15.0 to 0.0. A negative bias instructs the encoder to pay special attention to the crispness of transients in the encoded audio. The tradeoff for better transient response is a higher bitrate.
mjpeg Motion JPEG encoder.

optimal Compute and use optimal huffman tables.
wavpack WavPack lossless audio encoder.
Options
The equivalent options for wavpack command line utility are listed in parentheses.
Shared options
The following shared options are effective for this encoder. Only special notes about this particular encoder will be documented here. For the general meaning of the options, see the Codec Options chapter.
frame_size (--blocksize) For this encoder, the range for this option is between 128 and 131072. Default is automatically decided based on sample rate and number of channel.
For the complete formula of calculating default, see libavcodec/wavpackenc.c.
compression_level (-f, -h, -hh, and -x)
Private options
joint_stereo (-j) Set whether to enable joint stereo. Valid values are:
on (1) Force mid/side audio encoding.
off (0) Force left/right audio encoding.
auto Let the encoder decide automatically.
optimize_mono Set whether to enable optimization for mono. This option is only effective for non-mono streams. Available values:
on enabled
off disabled
VIDEO ENCODERS A description of some of the currently available video encoders follows.
a64_multi, a64_multi5 A64 / Commodore 64 multicolor charset encoder. "a64_multi5" is extended with 5th color (colram).
Cinepak frames, sometimes sooner.
q:v integer Quality factor. Lower is better. Higher gives lower bitrate. The following table lists bitrates when encoding akiyo_cif.y4m for various values of "-q:v" with "-g 100":
"-q:v 1" 1918 kb/s "-q:v 2" 1735 kb/s "-q:v 4" 1500 kb/s "-q:v 10" 1041 kb/s "-q:v 20" 826 kb/s "-q:v 40" 553 kb/s "-q:v 100" 394 kb/s "-q:v 200" 312 kb/s "-q:v 400" 266 kb/s "-q:v 1000" 237 kb/s max_extra_cb_iterations integer Max extra codebook recalculation passes, more is better and slower.
skip_empty_cb boolean Avoid wasting bytes, ignore vintage MacOS decoder.
max_strips integer min_strips integer The minimum and maximum number of strips to use. Wider range sometimes improves quality. More strips is generally better quality but costs more bits. Fewer strips tend to yield more keyframes. Vintage compatible is 1..3.
strip_number_adaptivity integer How much number of strips is allowed to change between frames. Higher is better but slower.
GIF GIF image/animation encoder.
Options
gifflags integer Sets the flags used for GIF encoding.
offsetting Enables picture offsetting.
Default is enabled.
transdiff Enables transparency detection between frames.
Default is enabled.
gifimage integer Enables encoding one full GIF image per frame, rather than an animated GIF.
Default value is 0.
global_palette integer
Hap Vidvox Hap video encoder.
Options
format integer Specifies the Hap format to encode.
hap hap_alpha hap_q
Default value is hap.
chunks integer Specifies the number of chunks to split frames into, between 1 and 64. This permits multithreaded decoding of large frames, potentially at the cost of data-rate. The encoder may modify this value to divide frames evenly.
Default value is 1.
compressor integer Specifies the second-stage compressor to use. If set to none, chunks will be limited to 1, as chunked uncompressed frames offer no benefit.
none snappy
Default value is snappy.
jpeg2000 The native jpeg 2000 encoder is lossy by default, the "-q:v" option can be used to set the encoding quality. Lossless encoding can be selected with "-pred 1".
Options
format integer Can be set to either "j2k" or "jp2" (the default) that makes it possible to store non-rgb pix_fmts.
tile_width integer Sets tile width. Range is 1 to 1073741824. Default is 256.
tile_height integer Sets tile height. Range is 1 to 1073741824. Default is 256.
pred integer Allows setting the discrete wavelet transform (DWT) type
dwt97int (Lossy) dwt53 (Lossless)
Default is "dwt97int"
sop boolean Enable this to add SOP marker at the start of each packet. Disabled Sets the progression order to be used by the encoder. Possible values are:
lrcp rlcp rpcl pcrl cprl
Set to "lrcp" by default.
layer_rates string By default, when this option is not used, compression is done using the quality metric. This option allows for compression using compression ratio. The compression ratio for each level could be specified. The compression ratio of a layer "l" species the what ratio of total file size is contained in the first "l" layers.
Example usage:
ffmpeg -i input.bmp -c:v jpeg2000 -layer_rates "100,10,1" output.j2k
This would compress the image to contain 3 layers, where the data contained in the first layer would be compressed by 1000 times, compressed by 100 in the first two layers, and shall contain all data while using all 3 layers.
librav1e rav1e AV1 encoder wrapper.
Requires the presence of the rav1e headers and library during configuration. You need to explicitly configure the build with "--enable-librav1e".
Options
qmax Sets the maximum quantizer to use when using bitrate mode.
qmin Sets the minimum quantizer to use when using bitrate mode.
qp Uses quantizer mode to encode at the given quantizer (0-255).
speed Selects the speed preset (0-10) to encode with.
tiles Selects how many tiles to encode with.
tile-rows Selects how many rows of tiles to encode with.
tile-columns Selects how many columns of tiles to encode with.
rav1e-params Set rav1e options using a list of key=value pairs separated by ":". See rav1e --help for a list of options.
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.
variance (1) Variance-based.
complexity (2) Complexity-based.
cyclic (3) Cyclic refresh.
tune (tune) Set the distortion metric the encoder is tuned with. Default is "psnr".
psnr (0) ssim (1) lag-in-frames Set the maximum number of frames which the encoder may keep in flight at any one time for lookahead purposes. Defaults to the internal default of the library.
error-resilience Enable error resilience features:
default Improve resilience against losses of whole frames.
Not enabled by default.
crf Set the quality/size tradeoff for constant-quality (no bitrate target) and constrained-quality (with maximum bitrate target) modes. Valid range is 0 to 63, higher numbers indicating lower quality and smaller output size. Only used if set; by default only the bitrate target is used.
static-thresh Set a change threshold on blocks below which they will be skipped by the encoder. Defined in arbitrary units as a nonnegative integer, defaulting to zero (no blocks are skipped).
drop-threshold Set a threshold for dropping frames when close to rate control bounds. Defined as a percentage of the target buffer - when the rate control buffer falls below this percentage, frames will be dropped until it has refilled above the threshold. Defaults to zero (no frames are dropped).
denoise-noise-level (level) Amount of noise to be removed for grain synthesis. Grain synthesis is disabled if this option is not set or set to 0.
denoise-block-size (pixels) Block size used for denoising for grain synthesis. If not set, AV1 codec uses the default value of 32.
undershoot-pct (pct) Set datarate undershoot (min) percentage of the target bitrate. Range is -1 to 100. Default is -1.
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-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.
Set libaom options using a list of key=value pairs separated by ":". For a list of supported options, see aomenc --help under the section "AV1 Specific Options".
For example to specify libaom encoding options with -aom-params:
ffmpeg -i input -c:v libaom-av1 -b:v 500K -aom-params tune=psnr:enable-tpl-model=1 output.mp4
libsvtav1 SVT-AV1 encoder wrapper.
Requires the presence of the SVT-AV1 headers and library during configuration. You need to explicitly configure the build with "--enable-libsvtav1".
Options
profile Set the encoding profile.
main high professional level Set the operating point level. For example: '4.0'
hielevel Set the Hierarchical prediction levels.
3level 4level This is the default.
tier Set the operating point tier.
main This is the default.
high qmax Set the maximum quantizer to use when using a bitrate mode.
qmin Set the minimum quantizer to use when using a bitrate mode.
crf Constant rate factor value used in crf rate control mode (0-63).
qp Set the quantizer used in cqp rate control mode (0-63).
sc_detection Enable scene change detection.
la_depth Set number of frames to look ahead (0-120).
preset Set the quality-speed tradeoff, in the range 0 to 13. Higher values are faster but lower quality.
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.
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", 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
o Set maximum constant quality (VBR) encoding with ffmpeg:
ffmpeg -i INPUT -codec:v libtheora -q:v 10 OUTPUT.ogg
o 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
overshoot-pct Set datarate overshoot (max) percentage of the target bitrate.
skip_threshold (drop-frame) qcomp (bias-pct) maxrate (maxsection-pct) Set GOP max bitrate in bits/s. Note vpxenc's option is specified as a percentage of the target bitrate, the libvpx wrapper converts this value as follows: "(maxrate * 100 / bitrate)".
minrate (minsection-pct) Set GOP min bitrate in bits/s. Note vpxenc's option is specified as a percentage of the target bitrate, the libvpx wrapper converts this value as follows: "(minrate * 100 / bitrate)".
minrate, maxrate, b end-usage=cbr "(minrate == maxrate == bitrate)".
crf (end-usage=cq, cq-level) tune (tune) psnr (psnr) ssim (ssim) quality, deadline (deadline) best Use best quality deadline. Poorly named and quite slow, this option should be avoided as it may give worse quality output than good.
good Use good quality deadline. This is a good trade-off between speed and quality when used with the cpu-used option.
realtime Use realtime quality deadline.
speed, cpu-used (cpu-used) Set quality/speed ratio modifier. Higher values speed up the encode at the cost of quality.
nr (noise-sensitivity) static-thresh Set a change threshold on blocks below which they will be skipped by the encoder.
slices (token-parts) Note that FFmpeg's slices option gives the total number of partitions, while vpxenc's token-parts is given as "log2(partitions)".
max-intra-rate Set maximum I-frame bitrate as a percentage of the target bitrate. A value of 0 means unlimited.
force_key_frames "VPX_EFLAG_FORCE_KF"
Alternate reference frame related auto-alt-ref Enable use of alternate reference frames (2-pass only). Values Set altref noise reduction filter type: backward, forward, centered.
arnr-strength Set altref noise reduction filter strength.
rc-lookahead, lag-in-frames (lag-in-frames) Set number of frames to look ahead for frametype and ratecontrol.
min-gf-interval Set minimum golden/alternate reference frame interval (VP9 only).
error-resilient Enable error resiliency features.
sharpness integer Increase sharpness at the expense of lower PSNR. The valid range is [0, 7].
ts-parameters Sets the temporal scalability configuration using a :-separated list of key=value pairs. For example, to specify temporal scalability parameters with "ffmpeg":
ffmpeg -i INPUT -c:v libvpx -ts-parameters ts_number_layers=3:\ ts_target_bitrate=250,500,1000:ts_rate_decimator=4,2,1:\ ts_periodicity=4:ts_layer_id=0,2,1,2:ts_layering_mode=3 OUTPUT
Below is a brief explanation of each of the parameters, please refer to "struct vpx_codec_enc_cfg" in "vpx/vpx_encoder.h" for more details.
ts_number_layers Number of temporal coding layers.
ts_target_bitrate Target bitrate for each temporal layer (in kbps). (bitrate should be inclusive of the lower temporal layer).
ts_rate_decimator Frame rate decimation factor for each temporal layer.
ts_periodicity Length of the sequence defining frame temporal layer membership.
ts_layer_id Template defining the membership of frames to temporal layers.
ts_layering_mode (optional) Selecting the temporal structure from a set of pre- defined temporal layering modes. Currently supports the following options.
0 No temporal layering flags are provided internally, relies on flags being passed in using "metadata" field in "AVFrame" with following keys. temporal_id Explicitly sets the temporal id of the current frame to encode.
2 Two temporal layers. 0-1...
3 Three temporal layers. 0-2-1-2...; with single reference frame.
4 Same as option "3", except there is a dependency between the two temporal layer 2 frames within the temporal period.
VP9-specific options lossless Enable lossless mode.
tile-columns Set number of tile columns to use. Note this is given as "log2(tile_columns)". For example, 8 tile columns would be requested by setting the tile-columns option to 3.
tile-rows Set number of tile rows to use. Note this is given as "log2(tile_rows)". For example, 4 tile rows would be requested by setting the tile-rows option to 2.
frame-parallel Enable frame parallel decodability features.
aq-mode Set adaptive quantization mode (0: off (default), 1: variance 2: complexity, 3: cyclic refresh, 4: equator360).
colorspace color-space Set input color space. The VP9 bitstream supports signaling the following colorspaces:
rgb ssRRGGBB bt709 bbtt770099 unspecified uunnkknnoowwnn bt470bg bbtt660011 smpte170m ssmmppttee117700 smpte240m ssmmppttee224400 bt2020_ncl bbtt22002200 row-mt boolean Enable row based multi-threading.
tune-content Set content type: default (0), screen (1), film (2).
corpus-complexity Corpus VBR mode is a variant of standard VBR where the complexity distribution midpoint is passed in rather than calculated for a specific clip or chunk.
The valid range is [0, 10000]. 0 (default) uses standard VBR.
enable-tpl boolean Enable temporal dependency model. av_dict_set(&av_frame->metadata, "ref-frame-config", \ "rfc_update_buffer_slot=7:rfc_lst_fb_idx=0:rfc_gld_fb_idx=1:rfc_alt_fb_idx=2:rfc_reference_last=0:rfc_reference_golden=0:rfc_reference_alt_ref=0");
rfc_update_buffer_slot Indicates the buffer slot number to update
rfc_update_last Indicates whether to update the LAST frame
rfc_update_golden Indicates whether to update GOLDEN frame
rfc_update_alt_ref Indicates whether to update ALT_REF frame
rfc_lst_fb_idx LAST frame buffer index
rfc_gld_fb_idx GOLDEN frame buffer index
rfc_alt_fb_idx ALT_REF frame buffer index
rfc_reference_last Indicates whether to reference LAST frame
rfc_reference_golden Indicates whether to reference GOLDEN frame
rfc_reference_alt_ref Indicates whether to reference ALT_REF frame
rfc_reference_duration Indicates frame duration
For more information about libvpx see: <http://www.webmproject.org/>
libwebp libwebp WebP Image encoder wrapper
libwebp is Google's official encoder for WebP images. It can encode in either lossy or lossless mode. Lossy images are essentially a wrapper around a VP8 frame. Lossless images are a separate codec developed by Google.
Pixel Format
Currently, libwebp only supports YUV420 for lossy and RGB for lossless due to limitations of the format and libwebp. Alpha is supported for either mode. Because of API limitations, if RGB is passed in when encoding lossy or YUV is passed in for encoding lossless, the pixel format will automatically be converted using functions from libwebp. This is not ideal and is done only for convenience.
Options
-lossless boolean Enables/Disables use of lossless mode. Default is 0. compression tools used, and varies the combination of these tools. This maps to the method option in libwebp. The valid range is 0 to 6. Default is 4.
-quality float For lossy encoding, this controls image quality. For lossless encoding, this controls the effort and time spent in compression. Range is 0 to 100. Default is 75.
-preset type Configuration preset. This does some automatic settings based on the general type of the image.
none Do not use a preset.
default Use the encoder default.
picture Digital picture, like portrait, inner shot
photo Outdoor photograph, with natural lighting
drawing Hand or line drawing, with high-contrast details
icon Small-sized colorful images
text Text-like
libx264, libx264rgb x264 H.264/MPEG-4 AVC encoder wrapper.
This encoder requires the presence of the libx264 headers and library during configuration. You need to explicitly configure the build with "--enable-libx264".
libx264 supports an impressive number of features, including 8x8 and 4x4 adaptive spatial transform, adaptive B-frame placement, CAVLC/CABAC entropy coding, interlacing (MBAFF), lossless mode, psy optimizations for detail retention (adaptive quantization, psy-RD, psy-trellis).
Many libx264 encoder options are mapped to FFmpeg global codec options, while unique encoder options are provided through private options. Additionally the x264opts and x264-params private options allows one to pass a list of key=value tuples as accepted by the libx264 "x264_param_parse" function.
The x264 project website is at <http://www.videolan.org/developers/x264.html>.
The libx264rgb encoder is the same as libx264, except it accepts packed RGB pixel formats as input instead of YUV.
Supported Pixel Formats x264-equivalent options or values are listed in parentheses for easy migration.
To reduce the duplication of documentation, only the private options and some others requiring special attention are documented here. For the documentation of the undocumented generic options, see the Codec Options chapter.
To get a more accurate and extensive documentation of the libx264 options, invoke the command x264 --fullhelp or consult the libx264 documentation.
b (bitrate) Set bitrate in bits/s. Note that FFmpeg's b option is expressed in bits/s, while x264's bitrate is in kilobits/s.
bf (bframes) g (keyint) qmin (qpmin) Minimum quantizer scale.
qmax (qpmax) Maximum quantizer scale.
qdiff (qpstep) Maximum difference between quantizer scales.
qblur (qblur) Quantizer curve blur
qcomp (qcomp) Quantizer curve compression factor
refs (ref) Number of reference frames each P-frame can use. The range is from 0-16.
sc_threshold (scenecut) Sets the threshold for the scene change detection.
trellis (trellis) Performs Trellis quantization to increase efficiency. Enabled by default.
nr (nr) me_range (merange) Maximum range of the motion search in pixels.
me_method (me) Set motion estimation method. Possible values in the decreasing order of speed:
dia (dia) epzs (dia) Diamond search with radius 1 (fastest). epzs is an alias for dia.
hex (hex) Hexagonal search with radius 2.
tesa (tesa) Hadamard exhaustive search (slowest).
forced-idr Normally, when forcing a I-frame type, the encoder can select any type of I-frame. This option forces it to choose an IDR-frame.
subq (subme) Sub-pixel motion estimation method.
b_strategy (b-adapt) Adaptive B-frame placement decision algorithm. Use only on first- pass.
keyint_min (min-keyint) Minimum GOP size.
coder Set entropy encoder. Possible values:
ac Enable CABAC.
vlc Enable CAVLC and disable CABAC. It generates the same effect as x264's --no-cabac option.
cmp Set full pixel motion estimation comparison algorithm. Possible values:
chroma Enable chroma in motion estimation.
sad Ignore chroma in motion estimation. It generates the same effect as x264's --no-chroma-me option.
threads (threads) Number of encoding threads.
thread_type Set multithreading technique. Possible values:
slice Slice-based multithreading. It generates the same effect as x264's --sliced-threads option.
frame Frame-based multithreading.
flags Set encoding flags. It can be used to disable closed GOP and enable open GOP by setting it to "-cgop". The result is similar to the behavior of x264's --open-gop option.
rc_init_occupancy (vbv-init) preset (preset) Set the encoding preset.
tune (tune) Set tuning of the encoding params.
crf (crf) Set the quality for constant quality mode.
crf_max (crf-max) In CRF mode, prevents VBV from lowering quality beyond this point.
qp (qp) Set constant quantization rate control method parameter.
aq-mode (aq-mode) Set AQ method. Possible values:
none (0) Disabled.
variance (1) Variance AQ (complexity mask).
autovariance (2) Auto-variance AQ (experimental).
aq-strength (aq-strength) Set AQ strength, reduce blocking and blurring in flat and textured areas.
psy Use psychovisual optimizations when set to 1. When set to 0, it has the same effect as x264's --no-psy option.
psy-rd (psy-rd) Set strength of psychovisual optimization, in psy-rd:psy-trellis format.
rc-lookahead (rc-lookahead) Set number of frames to look ahead for frametype and ratecontrol.
weightb Enable weighted prediction for B-frames when set to 1. When set to 0, it has the same effect as x264's --no-weightb option.
weightp (weightp) Set weighted prediction method for P-frames. Possible values:
none (0) Disabled
simple (1) Enable only weighted refs
smart (2) Enable both weighted refs and duplicates
ssim (ssim) Enable calculation and printing SSIM stats after the encoding.
intra-refresh (intra-refresh) Enable the use of Periodic Intra Refresh instead of IDR frames when set to 1.
avcintra-class (class) b-bias (b-bias) Set the influence on how often B-frames are used.
b-pyramid (b-pyramid) Set method for keeping of some B-frames as references. Possible values:
none (none) Disabled.
strict (strict) Strictly hierarchical pyramid.
normal (normal) Non-strict (not Blu-ray compatible).
mixed-refs Enable the use of one reference per partition, as opposed to one reference per macroblock when set to 1. When set to 0, it has the same effect as x264's --no-mixed-refs option.
8x8dct Enable adaptive spatial transform (high profile 8x8 transform) when set to 1. When set to 0, it has the same effect as x264's --no-8x8dct option.
fast-pskip Enable early SKIP detection on P-frames when set to 1. When set to 0, it has the same effect as x264's --no-fast-pskip option.
aud (aud) Enable use of access unit delimiters when set to 1.
mbtree Enable use macroblock tree ratecontrol when set to 1. When set to 0, it has the same effect as x264's --no-mbtree option.
deblock (deblock) Set loop filter parameters, in alpha:beta form.
cplxblur (cplxblur) Set fluctuations reduction in QP (before curve compression).
partitions (partitions) Set partitions to consider as a comma-separated list of. Possible values in the list:
p8x8 8x8 P-frame partition.
p4x4 4x4 P-frame partition.
b8x8 4x4 B-frame partition.
i8x8 8x8 I-frame partition.

all (all) Consider every partition.
direct-pred (direct) Set direct MV prediction mode. Possible values:
none (none) Disable MV prediction.
spatial (spatial) Enable spatial predicting.
temporal (temporal) Enable temporal predicting.
auto (auto) Automatically decided.
slice-max-size (slice-max-size) Set the limit of the size of each slice in bytes. If not specified but RTP payload size (ps) is specified, that is used.
stats (stats) Set the file name for multi-pass stats.
nal-hrd (nal-hrd) Set signal HRD information (requires vbv-bufsize to be set). Possible values:
none (none) Disable HRD information signaling.
vbr (vbr) Variable bit rate.
cbr (cbr) Constant bit rate (not allowed in MP4 container).
x264opts (N.A.) Set any x264 option, see x264 --fullhelp for a list.
Argument is a list of key=value couples separated by ":". In filter and psy-rd options that use ":" as a separator themselves, use "," instead. They accept it as well since long ago but this is kept undocumented for some reason.
For example to specify libx264 encoding options with ffmpeg:
ffmpeg -i foo.mpg -c:v libx264 -x264opts keyint=123:min-keyint=20 -an out.mkv
a53cc boolean Import closed captions (which must be ATSC compatible format) into output. Only the mpeg2 and h264 decoders provide these. Default is 1 (on).
udu_sei boolean Import user data unregistered SEI if available into output. Default is 0 (off).
For example to specify libx264 encoding options with ffmpeg:
ffmpeg -i INPUT -c:v libx264 -x264-params level=30:bframes=0:weightp=0:\ cabac=0:ref=1:vbv-maxrate=768:vbv-bufsize=2000:analyse=all:me=umh:\ no-fast-pskip=1:subq=6:8x8dct=0:trellis=0 OUTPUT
Encoding ffpresets for common usages are provided so they can be used with the general presets system (e.g. passing the pre option).
libx265 x265 H.265/HEVC encoder wrapper.
This encoder requires the presence of the libx265 headers and library during configuration. You need to explicitly configure the build with --enable-libx265.
Options
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
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:
o b / bit_rate
o g / gop_size
o 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 ":".

This encoder requires the presence of the libxvidcore headers and library during configuration. You need to explicitly configure the build with "--enable-libxvid --enable-gpl".
The native "mpeg4" encoder supports the MPEG-4 Part 2 format, so users can encode to this format without this library.
Options
The following options are supported by the libxvid wrapper. Some of the following options are listed but are not documented, and correspond to shared codec options. See the Codec Options chapter for their documentation. The other shared options which are not listed have no effect for the libxvid encoder.
b g qmin qmax mpeg_quant threads bf b_qfactor b_qoffset flags Set specific encoding flags. Possible values:
mv4 Use four motion vector by macroblock.
aic Enable high quality AC prediction.
gray Only encode grayscale.
gmc Enable the use of global motion compensation (GMC).
qpel Enable quarter-pixel motion compensation.
cgop Enable closed GOP.
global_header Place global headers in extradata instead of every keyframe.
trellis me_method Set motion estimation method. Possible values in decreasing order of speed and increasing order of quality:
zero Use no motion estimation (default).
phods x1 log Enable advanced diamond zonal search for 16x16 blocks and half- pixel refinement for 16x16 blocks. x1 and log are aliases for phods. Enable all of the things described above, plus extended 16x16 and 8x8 blocks search.
mbd Set macroblock decision algorithm. Possible values in the increasing order of quality:
simple Use macroblock comparing function algorithm (default).
bits Enable rate distortion-based half pixel and quarter pixel refinement for 16x16 blocks.
rd Enable all of the things described above, plus rate distortion- based half pixel and quarter pixel refinement for 8x8 blocks, and rate distortion-based search using square pattern.
lumi_aq Enable lumi masking adaptive quantization when set to 1. Default is 0 (disabled).
variance_aq Enable variance adaptive quantization when set to 1. Default is 0 (disabled).
When combined with lumi_aq, the resulting quality will not be better than any of the two specified individually. In other words, the resulting quality will be the worse one of the two effects.
ssim Set structural similarity (SSIM) displaying method. Possible values:
off Disable displaying of SSIM information.
avg Output average SSIM at the end of encoding to stdout. The format of showing the average SSIM is:
Average SSIM: %f
For users who are not familiar with C, %f means a float number, or a decimal (e.g. 0.939232).
frame Output both per-frame SSIM data during encoding and average SSIM at the end of encoding to stdout. The format of per-frame information is:
SSIM: avg: %1.3f min: %1.3f max: %1.3f
For users who are not familiar with C, %1.3f means a float number rounded to 3 digits after the dot (e.g. 0.932).
ssim_acc Set SSIM accuracy. Valid options are integers within the range of 0-4, while 0 gives the most accurate result and 4 computes the fastest.
MediaFoundation MPEG-2 video encoder.
Options
profile Select the mpeg2 profile to encode:
422 high ss Spatially Scalable
snr SNR Scalable
main simple level Select the mpeg2 level to encode:
high high1440 main low seq_disp_ext integer Specifies if the encoder should write a sequence_display_extension to the output.
-1 auto Decide automatically to write it or not (this is the default) by checking if the data to be written is different from the default or unspecified values.
0 never Never write it.
1 always Always write it.
video_format integer Specifies the video_format written into the sequence display extension indicating the source of the video pictures. The default is unspecified, can be component, pal, ntsc, secam or mac. For maximum compatibility, use component.
a53cc boolean Import closed captions (which must be ATSC compatible format) into output. Default is 1 (on).
png PNG image encoder.
Private options
dpi integer Set physical density of pixels, in dots per inch, unset by default
dpm integer
Private Options for prores-ks
profile integer Select the ProRes profile to encode
proxy lt standard hq 4444 4444xq quant_mat integer Select quantization matrix.
auto default proxy lt standard hq
If set to auto, the matrix matching the profile will be picked. If not set, the matrix providing the highest quality, default, will be picked.
bits_per_mb integer How many bits to allot for coding one macroblock. Different profiles use between 200 and 2400 bits per macroblock, the maximum is 8000.
mbs_per_slice integer Number of macroblocks in each slice (1-8); the default value (8) should be good in almost all situations.
vendor string Override the 4-byte vendor ID. A custom vendor ID like apl0 would claim the stream was produced by the Apple encoder.
alpha_bits integer Specify number of bits for alpha component. Possible values are 0, 8 and 16. Use 0 to disable alpha plane coding.
Speed considerations
In the default mode of operation the encoder has to honor frame constraints (i.e. not produce frames with size bigger than requested) while still making output picture as good as possible. A frame containing a lot of small details is harder to compress and the encoder would spend more time searching for appropriate quantizers for each slice.
Setting a higher bits_per_mb limit will improve the speed.
For the fastest encoding speed set the qscale parameter (4 is the recommended value) and do not set a size constraint.
QSV Encoders The family of Intel QuickSync Video encoders (MPEG-2, H.264, HEVC, Specifically this means either
- CQP - constant quantizer scale, when the qscale codec flag is also set (the -qscale ffmpeg option).
- LA_ICQ - intelligent constant quality with lookahead, when the look_ahead option is also set.
- ICQ -- intelligent constant quality otherwise. For the ICQ modes, global quality range is 1 to 51, with 1 being the best quality.
o Otherwise, a bitrate-based mode is used. For all of those, you should specify at least the desired average bitrate with the b option.
- LA - VBR with lookahead, when the look_ahead option is specified.
- VCM - video conferencing mode, when the vcm option is set.
- CBR - constant bitrate, when maxrate is specified and equal to the average bitrate.
- VBR - variable bitrate, when maxrate is specified, but is higher than the average bitrate.
- AVBR - average VBR mode, when maxrate is not specified, both avbr_accuracy and avbr_convergence are set to non-zero. This mode is available for H264 and HEVC on Windows.
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:
o g/gop_size -> GopPicSize
o bf/max_b_frames+1 -> GopRefDist
o rc_init_occupancy/rc_initial_buffer_occupancy -> InitialDelayInKB
o slices -> NumSlice
o refs -> NumRefFrame
o b_strategy/b_frame_strategy -> BRefType
o cgop/CLOSED_GOP codec flag -> GopOptFlag
o 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.
o Setting the coder option to the value vlc will make the H.264 Specifies how many asynchronous operations an application performs before the application explicitly synchronizes the result. If zero, the value is not specified.
preset This option itemizes a range of choices from veryfast (best speed) to veryslow (best quality).
veryfast faster fast medium slow slower veryslow forced_idr Forcing I frames as IDR frames.
low_power For encoders set this flag to ON to reduce power consumption and GPU usage.
Runtime Options
Following options can be used durning qsv encoding.
global_quality i_quant_factor i_quant_offset b_quant_factor b_quant_offset Supported in h264_qsv and hevc_qsv. Change these value to reset qsv codec's qp configuration.
max_frame_size Supported in h264_qsv and hevc_qsv. Change this value to reset qsv codec's MaxFrameSize configuration.
gop_size Change this value to reset qsv codec's gop configuration.
int_ref_type int_ref_cycle_size int_ref_qp_delta int_ref_cycle_dist Supported in h264_qsv and hevc_qsv. Change these value to reset qsv codec's Intra Refresh configuration.
qmax qmin max_qp_i min_qp_i max_qp_p min_qp_p max_qp_b min_qp_b Supported in h264_qsv. Change these value to reset qsv codec's max/min qp configuration.
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 This flag controls changing of frame type from B to P.
p_strategy Enable P-pyramid: 0-default 1-simple 2-pyramid(bf need to be set to 0).
b_strategy This option controls usage of B frames as reference.
dblk_idc This option disable deblocking. It has value in range 0~2.
cavlc If set, CAVLC is used; if unset, CABAC is used for encoding.
vcm Video conferencing mode, please see ratecontrol method.
idr_interval Distance (in I-frames) between IDR frames.
pic_timing_sei Insert picture timing SEI with pic_struct_syntax element.
single_sei_nal_unit Put all the SEI messages into one NALU.
max_dec_frame_buffering Maximum number of frames buffered in the DPB.
look_ahead Use VBR algorithm with look ahead.
look_ahead_depth Depth of look ahead in number frames.
look_ahead_downsampling Downscaling factor for the frames saved for the lookahead analysis.
unknown auto off 2x 4x int_ref_type Specifies intra refresh type. The major goal of intra refresh is improvement of error resilience without significant impact on encoded bitstream size caused by I frames. The SDK encoder achieves this by encoding part of each frame in refresh cycle using intra MBs. none means no refresh. vertical means vertical refresh, by column of MBs. horizontal means horizontal refresh, by rows of MBs. slice means horizontal refresh by slices without overlapping. In case of slice, in_ref_cycle_size is ignored. To enable intra refresh, B frame should be set to 0.
int_ref_cycle_size Specifies number of pictures within refresh cycle starting from 2. 0 and 1 are invalid values.
int_ref_qp_delta frames.
profile unknown baseline main high a53cc Use A53 Closed Captions (if available).
aud Insert the Access Unit Delimiter NAL.
mfmode Multi-Frame Mode.
off auto repeat_pps Repeat pps for every frame.
max_qp_i Maximum video quantizer scale for I frame.
min_qp_i Minimum video quantizer scale for I frame.
max_qp_p Maximum video quantizer scale for P frame.
min_qp_p Minimum video quantizer scale for P frame.
max_qp_b Maximum video quantizer scale for B frame.
min_qp_b Minimum video quantizer scale for B frame.
scenario Provides a hint to encoder about the scenario for the encoding session.
unknown displayremoting videoconference archive livestreaming cameracapture videosurveillance gamestreaming remotegaming avbr_accuracy Accuracy of the AVBR ratecontrol (unit of tenth of percent).
avbr_convergence Convergence of the AVBR ratecontrol (unit of 100 frames)
The parameters avbr_accuracy and avbr_convergence are for the average variable bitrate control (AVBR) algorithm. The algorithm encoding. This option defines the usage of this metadata.
no_skip Frame skipping is disabled.
insert_dummy Encoder inserts into bitstream frame where all macroblocks are encoded as skipped.
insert_nothing Similar to insert_dummy, but encoder inserts nothing into bitstream. The skipped frames are still used in brc. For example, gop still include skipped frames, and the frames after skipped frames will be larger in size.
brc_only skip_frame metadata indicates the number of missed frames before the current frame.
HEVC Options
These options are used by hevc_qsv
extbrc Extended bitrate control.
recovery_point_sei Set this flag to insert the recovery point SEI message at the beginning of every intra refresh cycle.
rdo Enable rate distortion optimization.
max_frame_size Maximum encoded frame size in bytes.
max_frame_size_i Maximum encoded frame size for I frames in bytes. If this value is set as larger than zero, then for I frames the value set by max_frame_size is ignored.
max_frame_size_p Maximum encoded frame size for P frames in bytes. If this value is set as larger than zero, then for P frames the value set by max_frame_size is ignored.
max_slice_size Maximum encoded slice size in bytes.
mbbrc Setting this flag enables macroblock level bitrate control that generally improves subjective visual quality. Enabling this flag may have negative impact on performance and objective visual quality metric.
low_delay_brc Setting this flag turns on or off LowDelayBRC feautre in qsv plugin, which provides more accurate bitrate control to minimize the variance of bitstream size frame by frame. Value: -1-default 0-off 1-on
p_strategy Enable P-pyramid: 0-default 1-simple 2-pyramid(bf need to be set to 0).
b_strategy This option controls usage of B frames as reference.
dblk_idc This option disable deblocking. It has value in range 0~2.
idr_interval Distance (in I-frames) between IDR frames.
begin_only Output an IDR-frame only at the beginning of the stream.
load_plugin A user plugin to load in an internal session.
none hevc_sw hevc_hw load_plugins A :-separate list of hexadecimal plugin UIDs to load in an internal session.
look_ahead_depth Depth of look ahead in number frames, available when extbrc option is enabled.
profile Set the encoding profile (scc requires libmfx >= 1.32).
unknown main main10 mainsp rext scc tier Set the encoding tier (only level >= 4 can support high tier). This option only takes effect when the level option is specified.
main high gpb 1: GPB (generalized P/B frame)
0: regular P frame.
tile_cols Number of columns for tiled encoding.
tile_rows Number of rows for tiled encoding.
aud Insert the Access Unit Delimiter NAL.
pic_timing_sei Specifies intra refresh type. The major goal of intra refresh is improvement of error resilience without significant impact on encoded bitstream size caused by I frames. The SDK encoder achieves this by encoding part of each frame in refresh cycle using intra MBs. none means no refresh. vertical means vertical refresh, by column of MBs. horizontal means horizontal refresh, by rows of MBs. slice means horizontal refresh by slices without overlapping. In case of slice, in_ref_cycle_size is ignored. To enable intra refresh, B frame should be set to 0.
int_ref_cycle_size Specifies number of pictures within refresh cycle starting from 2. 0 and 1 are invalid values.
int_ref_qp_delta Specifies QP difference for inserted intra MBs. This is signed value in [-51, 51] range if target encoding bit-depth for luma samples is 8 and this range is [-63, 63] for 10 bit-depth or [-75, 75] for 12 bit-depth respectively.
int_ref_cycle_dist Distance between the beginnings of the intra-refresh cycles in frames.
max_qp_i Maximum video quantizer scale for I frame.
min_qp_i Minimum video quantizer scale for I frame.
max_qp_p Maximum video quantizer scale for P frame.
min_qp_p Minimum video quantizer scale for P frame.
max_qp_b Maximum video quantizer scale for B frame.
min_qp_b Minimum video quantizer scale for B frame.
scenario Provides a hint to encoder about the scenario for the encoding session.
unknown displayremoting videoconference archive livestreaming cameracapture videosurveillance gamestreaming remotegaming avbr_accuracy Accuracy of the AVBR ratecontrol (unit of tenth of percent).
avbr_convergence and the instant bitrate is not capped or padded.
skip_frame Use per-frame metadata "qsv_skip_frame" to skip frame when encoding. This option defines the usage of this metadata.
no_skip Frame skipping is disabled.
insert_dummy Encoder inserts into bitstream frame where all macroblocks are encoded as skipped.
insert_nothing Similar to insert_dummy, but encoder inserts nothing into bitstream. The skipped frames are still used in brc. For example, gop still include skipped frames, and the frames after skipped frames will be larger in size.
brc_only skip_frame metadata indicates the number of missed frames before the current frame.
MPEG2 Options
These options are used by mpeg2_qsv
profile unknown simple main high
VP9 Options
These options are used by vp9_qsv
profile unknown profile0 profile1 profile2 profile3 tile_cols Number of columns for tiled encoding (requires libmfx >= 1.29).
tile_rows Number of rows for tiled encoding (requires libmfx >= 1.29).
AV1 Options
These options are used by av1_qsv (requires libvpl).
profile unknown main tile_cols Number of columns for tiled encoding.
adaptive_b This flag controls changing of frame type from B to P.
b_strategy This option controls usage of B frames as reference.
extbrc Extended bitrate control.
look_ahead_depth Depth of look ahead in number frames, available when extbrc option is enabled.
low_delay_brc Setting this flag turns on or off LowDelayBRC feautre in qsv plugin, which provides more accurate bitrate control to minimize the variance of bitstream size frame by frame. Value: -1-default 0-off 1-on
max_frame_size Set the allowed max size in bytes for each frame. If the frame size exceeds the limitation, encoder will adjust the QP value to control the frame size. Invalid in CQP rate control mode.
snow Options
iterative_dia_size dia size for the iterative motion estimation
VAAPI encoders Wrappers for hardware encoders accessible via VAAPI.
These encoders only accept input in VAAPI hardware surfaces. If you have input in software frames, use the hwupload filter to upload them to the GPU.
The following standard libavcodec options are used:
o g / gop_size
o bf / max_b_frames
o profile
If not set, this will be determined automatically from the format of the input frames and the profiles supported by the driver.
o level
o b / bit_rate
o maxrate / rc_max_rate
o bufsize / rc_buffer_size
o rc_init_occupancy / rc_initial_buffer_occupancy
o compression_level o qmin
o qmax
o i_qfactor / i_quant_factor
o i_qoffset / i_quant_offset
o b_qfactor / b_quant_factor
o b_qoffset / b_quant_offset
o slices
All encoders support the following options:
low_power Some drivers/platforms offer a second encoder for some codecs intended to use less power than the default encoder; setting this option will attempt to use that encoder. Note that it may support a reduced feature set, so some other options may not be available in this mode.
idr_interval Set the number of normal intra frames between full-refresh (IDR) frames in open-GOP mode. The intra frames are still IRAPs, but will not include global headers and may have non-decodable leading pictures.
b_depth Set the B-frame reference depth. When set to one (the default), all B-frames will refer only to P- or I-frames. When set to greater values multiple layers of B-frames will be present, frames in each layer only referring to frames in higher layers.
async_depth Maximum processing parallelism. Increase this to improve single channel performance. This option doesn't work if driver doesn't implement vaSyncBuffer function. Please make sure there are enough hw_frames allocated if a large number of async_depth is used.
max_frame_size Set the allowed max size in bytes for each frame. If the frame size exceeds the limitation, encoder will adjust the QP value to control the frame size. Invalid in CQP rate control mode.
rc_mode Set the rate control mode to use. A given driver may only support a subset of modes.
Possible modes:
auto Choose the mode automatically based on driver support and the other options. This is the default.
CQP Constant-quality.
CBR Constant-bitrate.
AVBR Average variable bitrate.
Each encoder also has its own specific options:
h264_vaapi profile sets the value of profile_idc and the constraint_set*_flags. level sets the value of level_idc.
coder Set entropy encoder (default is cabac). Possible values:
ac cabac Use CABAC.
vlc cavlc Use CAVLC.
aud Include access unit delimiters in the stream (not included by default).
sei Set SEI message types to include. Some combination of the following values:
identifier Include a user_data_unregistered message containing information about the encoder.
timing Include picture timing parameters (buffering_period and pic_timing messages).
recovery_point Include recovery points where appropriate (recovery_point messages).
hevc_vaapi profile and level set the values of general_profile_idc and general_level_idc respectively.
aud Include access unit delimiters in the stream (not included by default).
tier Set general_tier_flag. This may affect the level chosen for the stream if it is not explicitly specified.
sei Set SEI message types to include. Some combination of the following values:
hdr Include HDR metadata if the input frames have it (mastering_display_colour_volume and content_light_level messages).
tiles Set the number of tiles to encode the input video with, as
For YUV, 4:2:0, 4:2:2 and 4:4:4 subsampling modes are supported. RGB is also supported, and will create an RGB JPEG.
jfif Include JFIF header in each frame (not included by default).
huffman Include standard huffman tables (on by default). Turning this off will save a few hundred bytes in each output frame, but may lose compatibility with some JPEG decoders which don't fully handle MJPEG.
mpeg2_vaapi profile and level set the value of profile_and_level_indication.
vp8_vaapi B-frames are not supported.
global_quality sets the q_idx used for non-key frames (range 0-127).
loop_filter_level loop_filter_sharpness Manually set the loop filter parameters.
vp9_vaapi global_quality sets the q_idx used for P-frames (range 0-255).
loop_filter_level loop_filter_sharpness Manually set the loop filter parameters.
B-frames are supported, but the output stream is always in encode order rather than display order. If B-frames are enabled, it may be necessary to use the vp9_raw_reorder bitstream filter to modify the output stream to display frames in the correct order.
Only normal frames are produced - the vp9_superframe bitstream filter may be required to produce a stream usable with all decoders.
vbn Vizrt Binary Image encoder.
This format is used by the broadcast vendor Vizrt for quick texture streaming. Advanced features of the format such as LZW compression of texture data or generation of mipmaps are not supported.
Options
format string Sets the texture compression used by the VBN file. Can be dxt1, dxt5 or raw. Default is dxt5.
vc2 SMPTE VC-2 (previously BBC Dirac Pro). This codec was primarily aimed at professional broadcasting but since it supports yuv420, yuv422 and yuv444 at 8 (limited range or full range), 10 or 12 bits, this makes it that's around 400Mbps). Higher values (close to the uncompressed bitrate) turn on lossless compression mode.
field_order Enables field coding when set (e.g. to tt - top field first) for interlaced inputs. Should increase compression with interlaced content as it splits the fields and encodes each separately.
wavelet_depth Sets the total amount of wavelet transforms to apply, between 1 and 5 (default). Lower values reduce compression and quality. Less capable decoders may not be able to handle values of wavelet_depth over 3.
wavelet_type Sets the transform type. Currently only 5_3 (LeGall) and 9_7 (Deslauriers-Dubuc) are implemented, with 9_7 being the one with better compression and thus is the default.
slice_width slice_height Sets the slice size for each slice. Larger values result in better compression. For compatibility with other more limited decoders use slice_width of 32 and slice_height of 8.
tolerance Sets the undershoot tolerance of the rate control system in percent. This is to prevent an expensive search from being run.
qm Sets the quantization matrix preset to use by default or when wavelet_depth is set to 5
- default Uses the default quantization matrix from the specifications, extended with values for the fifth level. This provides a good balance between keeping detail and omitting artifacts.
- flat Use a completely zeroed out quantization matrix. This increases PSNR but might reduce perception. Use in bogus benchmarks.
- color Reduces detail but attempts to preserve color at extremely low bitrates.
SUBTITLES ENCODERS dvdsub This codec encodes the bitmap subtitle format that is used in DVDs. Typically they are stored in VOBSUB file pairs (*.idx + *.sub), and they can also be used in Matroska files.
Options
palette Specify the global palette used by the bitmaps.
The format for this option is a string containing 16 24-bits hexadecimal numbers (without 0x prefix) separated by commas, for example "0d00ee, ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1, 7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c, typically one byte per subtitle on average.
By default, this work-around is disabled.
SEE ALSO ffmpeg(1), ffplay(1), ffprobe(1), libavcodec(3)
AUTHORS The FFmpeg developers.
For details about the authorship, see the Git history of the project (https://git.ffmpeg.org/ffmpeg), e.g. by typing the command git log in the FFmpeg source directory, or browsing the online repository at <https://git.ffmpeg.org/ffmpeg>.
Maintainers for the specific components are listed in the file MAINTAINERS in the source code tree.
FFMPEG-CODECS(1)