ffmpeg-codecs • man page

ffmpeg-codecs (1)

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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.
gmc: Use gmc.
mv0: Always try a mb with mv=<0,0>.
input_preserved
pass1: Use internal 2pass ratecontrol in first pass mode.
pass2: Use internal 2pass ratecontrol in second pass mode.
gray: Only decode/encode grayscale.
emu_edge: Do not draw edges.
psnr: Set error[?] variables during encoding.
truncated
naq: Normalize adaptive quantization.
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.
cbp: Deprecated, use mpegvideo private options instead.
qprd: Deprecated, use mpegvideo private options instead.
ilme: Apply interlaced motion estimation.
cgop: Use closed gop.

me_method integer (encoding,video)

Set motion estimation method.

Possible values:

zero: zero motion estimation (fastest)
full: full motion estimation (slowest)
epzs: EPZS
motion estimation (default)
esa: esa motion estimation (alias for full)
tesa: tesa motion estimation
dia: dia motion estimation (alias for epzs)
log: log motion estimation
phods: phods motion estimation
x1: X1 motion estimation
hex: hex motion estimation
umh: umh motion estimation
iter: iter motion estimation

extradata_size integer

Set extradata size.

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 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.

frame_size integer (encoding,audio)

Set audio frame size.

Each submitted frame except the last must contain exactly frame_size samples per channel. May be 0 when the codec has

CODEC_CAP_VARIABLE_FRAME_SIZE

set, in that case the frame size is not restricted. It is set by some decoders to indicate constant frame size.

frame_number integer

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.

rc_strategy integer (encoding,video)

Set ratecontrol method.

b_strategy integer (encoding,video)

Set strategy to choose between I/P/B-frames.

ps integer (encoding,video)

Set

RTP

payload size in bytes.

mv_bits integer

header_bits integer

i_tex_bits integer

p_tex_bits integer

i_count integer

p_count integer

skip_count integer

misc_bits integer

frame_bits integer

codec_tag integer

bug flags (decoding,video)

Workaround not auto detected encoder bugs.

Possible values:

autodetect
old_msmpeg4: some old lavc generated msmpeg4v3 files (no autodetection)
xvid_ilace: Xvid interlacing bug (autodetected if fourcc==XVIX)
ump4: (autodetected if fourcc==UMP4)
no_padding: padding bug (autodetected)
amv
ac_vlc: illegal vlc bug (autodetected per fourcc)
qpel_chroma
std_qpel: old standard qpel (autodetected per fourcc/version)
qpel_chroma2
direct_blocksize: direct-qpel-blocksize bug (autodetected per fourcc/version)
edge: edge padding bug (autodetected per fourcc/version)
hpel_chroma
dc_clip
ms: Workaround various bugs in microsoft broken decoders.
trunc: trancated frames

lelim integer (encoding,video)

Set single coefficient elimination threshold for luminance (negative values also consider

coefficient).

celim integer (encoding,video)

Set single coefficient elimination threshold for chrominance (negative values also consider dc coefficient)

strict integer (decoding/encoding,audio,video)

Specify how strictly to follow the standards.

Possible values:

very: strictly conform to a 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

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
aggressive: consider things that a sane encoder should not do as an error

has_b_frames integer

block_align integer

mpeg_quant integer (encoding,video)

Use

MPEG

quantizers instead of H.263.

qsquish float (encoding,video)

How to keep quantizer between qmin and qmax (0 = clip, 1 = use differentiable function).

rc_qmod_amp float (encoding,video)

Set experimental quantizer modulation.

rc_qmod_freq integer (encoding,video)

Set experimental quantizer modulation.

rc_override_count integer

rc_eq string (encoding,video)

Set rate control equation. When computing the expression, besides the standard functions defined in the section 'Expression Evaluation', the following functions are available: bits2qp(bits), qp2bits(qp). Also the following constants are available: iTex pTex tex mv fCode iCount mcVar var isI isP isB avgQP qComp avgIITex avgPITex avgPPTex avgBPTex avgTex.

maxrate integer (encoding,audio,video)

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).

rc_buf_aggressivity float (encoding,video)

Currently useless.

i_qfactor float (encoding,video)

Set

factor between P and I frames.

i_qoffset float (encoding,video)

Set

offset between P and I frames.

rc_init_cplx float (encoding,video)

Set initial complexity for 1-pass encoding.

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
arm
altivec
sh4
simplearm
simplearmv5te
simplearmv6
simpleneon
simplealpha
ipp
xvidmmx
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

pred integer (encoding,video)

Set prediction method.

Possible values:

left
plane
median

aspect rational number (encoding,video)

Set sample aspect ratio.

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
)
mv: motion vector
dct_coeff
green_metadata: display complexity metadata for the upcoming frame, GoP or for a given duration.
skip
startcode
pts
er: error recognition
mmco: memory management control operations (H.264)
bugs
vis_qp: visualize quantization parameter (
QP
), lower
QP
are tinted greener
vis_mb_type: visualize block types
buffers: picture buffer allocations
thread_ops: threading operations
nomc: skip motion compensation

vismv integer (decoding,video)

Visualize motion vectors (MVs).

This option is deprecated, see the codecview filter instead.

Possible values:

pf: forward predicted MVs of P-frames
bf: forward predicted MVs of B-frames
bb: backward predicted MVs of B-frames

cmp integer (encoding,video)

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
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

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
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

dia_size integer (encoding,video)

Set diamond type & size for motion estimation.

last_pred integer (encoding,video)

Set amount of motion predictors from the previous frame.

preme integer (encoding,video)

Set pre motion estimation.

precmp integer (encoding,video)

Set pre motion estimation 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

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.

dtg_active_format integer

me_range integer (encoding,video)

Set limit motion vectors range (1023 for DivX player).

ibias integer (encoding,video)

Set intra quant bias.

pbias integer (encoding,video)

Set inter quant bias.

color_table_id integer

global_quality integer (encoding,audio,video)

coder integer (encoding,video)

Possible values:

vlc: variable length coder / huffman coder
ac: arithmetic coder
raw: raw (no encoding)
rle: run-length coder
deflate: deflate-based coder

context integer (encoding,video)

Set context model.

slice_flags integer

xvmc_acceleration 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

stream_codec_tag integer

sc_threshold integer (encoding,video)

Set scene change threshold.

lmin integer (encoding,video)

Set min lagrange factor (

VBR

lmax integer (encoding,video)

Set max lagrange factor (

VBR

nr integer (encoding,video)

Set noise reduction.

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)

Possible values:

fast: Allow non spec compliant speedup tricks.
sgop: Deprecated, use mpegvideo private options instead.
noout: Skip bitstream encoding.
ignorecrop: Ignore cropping information from sps.
local_header: 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.
skiprd: Deprecated, use mpegvideo private options instead.
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.

error integer (encoding,video)

qns integer (encoding,video)

Deprecated, use mpegvideo private options instead.

threads integer (decoding/encoding,video)

Possible values:

auto: detect a good number of threads

me_threshold integer (encoding,video)

Set motion estimation threshold.

mb_threshold integer (encoding,video)

Set macroblock threshold.

dc integer (encoding,video)

Set intra_dc_precision.

nssew integer (encoding,video)

Set nsse weight.

skip_top integer (decoding,video)

Set number of macroblock rows at the top which are skipped.

skip_bottom integer (decoding,video)

Set number of macroblock rows at the bottom which are skipped.

profile integer (encoding,audio,video)

Possible values:

unknown
aac_main
aac_low
aac_ssr
aac_ltp
aac_he
aac_he_v2
aac_ld
aac_eld
mpeg2_aac_low
mpeg2_aac_he
mpeg4_sp
mpeg4_core
mpeg4_main
mpeg4_asp
dts
dts_es
dts_96_24
dts_hd_hra
dts_hd_ma

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.

skip_threshold integer (encoding,video)

Set frame skip threshold.

skip_factor integer (encoding,video)

Set frame skip factor.

skip_exp integer (encoding,video)

Set frame skip exponent. Negative values behave identical to the corresponding positive ones, except that the score is normalized. Positive values exist primarily for compatibility reasons and are not so useful.

skipcmp integer (encoding,video)

Set frame skip 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

border_mask float (encoding,video)

Increase the quantizer for macroblocks close to borders.

mblmin integer (encoding,video)

Set min macroblock lagrange factor (

VBR

mblmax integer (encoding,video)

Set max macroblock lagrange factor (

VBR

mepc integer (encoding,video)

Set motion estimation bitrate penalty compensation (1.0 = 256).

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.
all: Discard all frames.

: Default value is default.

bidir_refine integer (encoding,video)

Refine the two motion vectors used in bidirectional macroblocks.

brd_scale integer (encoding,video)

Downscale frames for dynamic B-frame decision.

keyint_min integer (encoding,video)

Set minimum interval between IDR-frames.

refs integer (encoding,video)

Set reference frames to consider for motion compensation.

chromaoffset integer (encoding,video)

Set chroma qp offset from luma.

trellis integer (encoding,audio,video)

Set rate-distortion optimal quantization.

sc_factor integer (encoding,video)

Set value multiplied by qscale for each frame and added to scene_change_score.

mv0_threshold integer (encoding,video)

b_sensitivity integer (encoding,video)

Adjust sensitivity of b_frame_strategy 1.

compression_level integer (encoding,audio,video)

min_prediction_order integer (encoding,audio)

max_prediction_order integer (encoding,audio)

timecode_frame_start integer (encoding,video)

Set

GOP

timecode frame start number, in non drop frame format.

request_channels integer (decoding,audio)

Set desired number of audio channels.

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)

color_trc integer (decoding/encoding,video)

colorspace integer (decoding/encoding,video)

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.

chroma_sample_location integer (decoding/encoding,video)

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.

: Default value is slice+frame.

audio_service_type integer (encoding,audio)

Set audio service type.

Possible values:

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 integer (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 indention:

        ffprobe -dump_separator "
                                  "  -i ~/videos/matrixbench_mpeg2.mpg

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.

hevc

HEVC / H.265

decoder.

Note: the skip_loop_filter option has effect only at level "all".

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

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. 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.

FLAC

Decoder options

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

ffwavesynth

Internal wave synthetizer.

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

libcelt

libcelt decoder wrapper.

libcelt allows libavcodec to decode the Xiph

CELT

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

libgsm

libgsm decoder wrapper.

libgsm allows libavcodec to decode the

GSM

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

This decoder supports both the ordinary

GSM

and the Microsoft variant.

libilbc

libilbc decoder wrapper.

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

Options

The following option is supported by the libilbc wrapper.

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

libopencore-amrnb

libopencore-amrnb decoder wrapper.

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

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

libopencore-amrwb

libopencore-amrwb decoder wrapper.

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

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

libopus

libopus decoder wrapper.

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

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

SUBTITLES DECODERS

dvbsub

Options

compute_clut

-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 format as in VobSub. In DVDs, the palette is stored in the
IFO
file, and therefore not available when reading from dumped
VOB
files.
The format for this option is a string containing 16 24-bits hexadecimal numbers (without 0x prefix) separated by comas, for example "0d00ee, ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1, 7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c, 7c127b".
ifo_palette: Specify the
IFO
file from which the global palette is obtained. (experimental)
forced_subs_only: Only decode subtitle entries marked as forced. Some titles have forced and non-forced subtitles in the same track. Setting this flag to 1 will only keep the forced subtitles. Default value is 0.

libzvbi-teletext

Libzvbi allows libavcodec to decode

DVB

teletext pages and

DVB

teletext subtitles. Requires the presence of the libzvbi headers and library during configuration. You need to explicitly configure the build with "--enable-libzvbi".

Options

txt_page: List of teletext page numbers to decode. You may use the special * string to match all pages. Pages that do not match the specified list are dropped. Default value is *.
txt_chop_top: Discards the top teletext line. Default value is 1.
txt_format: Specifies the format of the decoded subtitles. The teletext decoder is capable of decoding the teletext pages to bitmaps or to simple text, you should use ``bitmap'' for teletext pages, because certain graphics and colors cannot be expressed in simple text. You might use ``text'' for teletext based subtitles if your application can handle simple text based subtitles. Default value is bitmap.
txt_left: X offset of generated bitmaps, default is 0.
txt_top: Y offset of generated bitmaps, default is 0.
txt_chop_spaces: Chops leading and trailing spaces and removes empty lines from the generated text. This option is useful for teletext based subtitles where empty spaces may be present at the start or at the end of the lines or empty lines may be present between the subtitle lines because of double-sized teletext charactes. Default value is 1.
txt_duration: Sets the display duration of the decoded teletext pages or subtitles in miliseconds. Default value is 30000 which is 30 seconds.
txt_transparent: Force transparent background of the generated teletext bitmaps. Default value is 0 which means an opaque (black) background.

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 an experimental FFmpeg-native

AAC

encoder. Currently only the low complexity (AAC-LC) profile is supported. To use this encoder, you must set strict option to experimental or lower.

As this encoder is experimental, unexpected behavior may exist from time to time. For a more stable

AAC

encoder, see libvo-aacenc. However, be warned that it has a worse quality reported by some users.

ac3 and ac3_fixed

AC-3

audio encoders.

These encoders implement part of

ATSC A/52:2010

and

ETSI TS 102 366,

as well as the undocumented RealAudio 3 (a.k.a. dnet).

The ac3 encoder uses floating-point math, while the ac3_fixed encoder only uses fixed-point integer math. This does not mean that one is always faster, just that one or the other may be better suited to a particular system. The floating-point encoder will generally produce better quality audio for a given bitrate. The ac3_fixed encoder is not the default codec for any of the output formats, so it must be specified explicitly using the option "-acodec ac3_fixed" in order to use it.

AC-3

Metadata

The

AC-3

metadata options are used to set parameters that describe the audio, but in most cases do not affect the audio encoding itself. Some of the options do directly affect or influence the decoding and playback of the resulting bitstream, while others are just for informational purposes. A few of the options will add bits to the output stream that could otherwise be used for audio data, and will thus affect the quality of the output. Those will be indicated accordingly with a note in the option list below.

These parameters are described in detail in several publicly-available documents.

*<<www.atsc.org/cms/standards/a_52-2010.pdf>>
*<<www.atsc.org/cms/standards/a_54a_with_corr_1.pdf>>
*<<www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/18_Metadata.Guide.pdf>>
*<<www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/46_DDEncodingGuidelines.pdf>>

Metadata Control Options

-per_frame_metadata boolean

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

0: The metadata values set at initialization will be used for every frame in the stream. (default)
1: Metadata values can be changed before encoding each frame.

Downmix Levels

-center_mixlev level

Center Mix Level. The amount of gain the decoder should apply to the center channel when downmixing to stereo. This field will only be written to the bitstream if a center channel is present. The value is specified as a scale factor. There are 3 valid values:

0.707: Apply -3dB gain
0.595: Apply -4.5dB gain (default)
0.500: Apply -6dB gain

-surround_mixlev level

Surround Mix Level. The amount of gain the decoder should apply to the surround channel(s) when downmixing to stereo. This field will only be written to the bitstream if one or more surround channels are present. The value is specified as a scale factor. There are 3 valid values:

0.707: Apply -3dB gain
0.500: Apply -6dB gain (default)
0.000: Silence Surround Channel(s)

Audio Production Information

Audio Production Information is optional information describing the mixing environment. Either none or both of the fields are written to the bitstream.

-mixing_level number

Mixing Level. Specifies peak sound pressure level (

SPL

) in the production environment when the mix was mastered. Valid values are 80 to 111, or -1 for unknown or not indicated. The default value is -1, but that value cannot be used if the Audio Production Information is written to the bitstream. Therefore, if the "room_type" option is not the default value, the "mixing_level" option must not be -1.

-room_type type

Room Type. Describes the equalization used during the final mixing session at the studio or on the dubbing stage. A large room is a dubbing stage with the industry standard X-curve equalization; a small room has flat equalization. This field will not be written to the bitstream if both the "mixing_level" option and the "room_type" option have the default values.

0
notindicated: Not Indicated (default)
1
large: Large Room
2
small: Small Room

Other Metadata Options

-copyright boolean

0
off: No Copyright Exists (default)
1
on: Copyright Exists

-dialnorm value

Dialogue Normalization. Indicates how far the average dialogue level of the program is below digital 100% full scale (0 dBFS). This parameter determines a level shift during audio reproduction that sets the average volume of the dialogue to a preset level. The goal is to match volume level between program sources. A value of -31dB will result in no volume level change, relative to the source volume, during audio reproduction. Valid values are whole numbers in the range -31 to -1, with -31 being the default.

-dsur_mode mode

Dolby Surround Mode. Specifies whether the stereo signal uses Dolby Surround (Pro Logic). This field will only be written to the bitstream if the audio stream is stereo. Using this option does

NOT

mean the encoder will actually apply Dolby Surround processing.

0
notindicated: Not Indicated (default)
1
off: Not Dolby Surround Encoded
2
on: Dolby Surround Encoded

-original boolean

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

0
off: Not Original Source
1
on: Original Source (default)

Extended Bitstream Information

The extended bitstream options are part of the Alternate Bit Stream Syntax as specified in Annex D of the A/52:2010 standard. It is grouped into 2 parts. If any one parameter in a group is specified, all values in that group will be written to the bitstream. Default values are used for those that are written but have not been specified. If the mixing levels are written, the decoder will use these values instead of the ones specified in the "center_mixlev" and "surround_mixlev" options if it supports the Alternate Bit Stream Syntax.

Extended Bitstream Information - Part 1

-dmix_mode mode

Preferred Stereo Downmix Mode. Allows the user to select either Lt/Rt (Dolby Surround) or Lo/Ro (normal stereo) as the preferred stereo downmix mode.

0
notindicated: Not Indicated (default)
1
ltrt: Lt/Rt Downmix Preferred
2
loro: Lo/Ro Downmix Preferred

-ltrt_cmixlev level

Lt/Rt Center Mix Level. The amount of gain the decoder should apply to the center channel when downmixing to stereo in Lt/Rt mode.

1.414: Apply +3dB gain
1.189: Apply +1.5dB gain
1.000: Apply 0dB gain
0.841: Apply -1.5dB gain
0.707: Apply -3.0dB gain
0.595: Apply -4.5dB gain (default)
0.500: Apply -6.0dB gain
0.000: Silence Center Channel

-ltrt_surmixlev level

Lt/Rt Surround Mix Level. The amount of gain the decoder should apply to the surround channel(s) when downmixing to stereo in Lt/Rt mode.

0.841: Apply -1.5dB gain
0.707: Apply -3.0dB gain
0.595: Apply -4.5dB gain
0.500: Apply -6.0dB gain (default)
0.000: Silence Surround Channel(s)

-loro_cmixlev level

Lo/Ro Center Mix Level. The amount of gain the decoder should apply to the center channel when downmixing to stereo in Lo/Ro mode.

1.414: Apply +3dB gain
1.189: Apply +1.5dB gain
1.000: Apply 0dB gain
0.841: Apply -1.5dB gain
0.707: Apply -3.0dB gain
0.595: Apply -4.5dB gain (default)
0.500: Apply -6.0dB gain
0.000: Silence Center Channel

-loro_surmixlev level

Lo/Ro Surround Mix Level. The amount of gain the decoder should apply to the surround channel(s) when downmixing to stereo in Lo/Ro mode.

0.841: Apply -1.5dB gain
0.707: Apply -3.0dB gain
0.595: Apply -4.5dB gain
0.500: Apply -6.0dB gain (default)
0.000: Silence Surround Channel(s)

Extended Bitstream Information - Part 2

-dsurex_mode mode

Dolby Surround

Mode. Indicates whether the stream uses Dolby Surround

(7.1 matrixed to 5.1). Using this option does

NOT

mean the encoder will actually apply Dolby Surround

processing.

0
notindicated: Not Indicated (default)
1
on: Dolby Surround
EX
Off
2
off: Dolby Surround
EX
On

-dheadphone_mode mode

Dolby Headphone Mode. Indicates whether the stream uses Dolby Headphone encoding (multi-channel matrixed to 2.0 for use with headphones). Using this option does

NOT

mean the encoder will actually apply Dolby Headphone processing.

0
notindicated: Not Indicated (default)
1
on: Dolby Headphone Off
2
off: Dolby Headphone On

-ad_conv_type type

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

HDCD A/D

conversion.

0
standard: Standard A/D Converter (default)
1
hdcd: HDCD A/D
Converter

Other

AC-3

Encoding Options

-stereo_rematrixing boolean: Stereo Rematrixing. Enables/Disables use of rematrixing for stereo input. This is an optional
AC-3
feature that increases quality by selectively encoding the left/right channels as mid/side. This option is enabled by default, and it is highly recommended that it be left as enabled except for testing purposes.

Floating-Point-Only

AC-3

Encoding Options

These options are only valid for the floating-point encoder and do not exist for the fixed-point encoder due to the corresponding features not being implemented in fixed-point.

-channel_coupling boolean

Enables/Disables use of channel coupling, which is an optional

AC-3

feature that increases quality by combining high frequency information from multiple channels into a single channel. The per-channel high frequency information is sent with less accuracy in both the frequency and time domains. This allows more bits to be used for lower frequencies while preserving enough information to reconstruct the high frequencies. This option is enabled by default for the floating-point encoder and should generally be left as enabled except for testing purposes or to increase encoding speed.

-1
auto: Selected by Encoder (default)
0
off: Disable Channel Coupling
1
on: Enable Channel Coupling

-cpl_start_band number

Coupling Start Band. Sets the channel coupling start band, from 1 to 15. If a value higher than the bandwidth is used, it will be reduced to 1 less than the coupling end band. If auto is used, the start band will be determined by the encoder based on the bit rate, sample rate, and channel layout. This option has no effect if channel coupling is disabled.

-1
auto: Selected by Encoder (default)

flac

FLAC

(Free Lossless Audio Codec) Encoder

Options

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

compression_level

Sets the compression level, which chooses defaults for many other options if they are not set explicitly.

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: Chanels are independently coded
left_side
right_side
mid_side

exact_rice_parameters

Chooses if rice parameters are calculated exactly or approximately. if set to 1 then they are chosen exactly, which slows the code down slightly and improves compression slightly.

multi_dim_quant

Multi Dimensional Quantization. If set to 1 then a 2nd stage

LPC

algorithm is applied after the first stage to finetune the coefficients. This is quite slow and slightly improves compression.

libfaac

AAC

(Advanced Audio Coding) encoder wrapper.

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

This encoder is considered to be of higher quality with respect to the the native experimental FFmpeg

AAC

encoder.

For more information see the libfaac project at <www.audiocoding.com/faac.html>.

Options

The following shared FFmpeg codec options are recognized.

The following options are supported by the libfaac wrapper. The faac-equivalent of the options are listed in parentheses.

b (-b)

Set bit rate in bits/s for

ABR

(Average Bit Rate) mode. If the bit rate is not explicitly specified, it is automatically set to a suitable value depending on the selected profile. faac bitrate is expressed in kilobits/s.

Note that libfaac does not support

CBR

(Constant Bit Rate) but only

ABR

(Average Bit Rate).

VBR

mode is enabled this option is ignored.

ar (-R)

Set audio sampling rate (in Hz).

ac (-c)

Set the number of audio channels.

cutoff (-C)

Set cutoff frequency. If not specified (or explicitly set to 0) it will use a value automatically computed by the library. Default value is 0.

profile

Set audio profile.

The following profiles are recognized:

aac_main: Main
AAC
(Main)
aac_low: Low Complexity
AAC
(
LC
)
aac_ssr: Scalable Sample Rate (
SSR
)
aac_ltp: Long Term Prediction (
LTP
)

: If not specified it is set to aac_low.

flags +qscale

Set constant quality

VBR

(Variable Bit Rate) mode.

global_quality

Set quality in

VBR

mode as an integer number of lambda units.

Only relevant when

VBR

mode is enabled with "flags +qscale". The value is converted to

units by dividing it by "FF_QP2LAMBDA", and used to set the quality value used by libfaac. A reasonable range for the option value in

units is [10-500], the higher the value the higher the quality.

q (-q)

Enable

VBR

mode when set to a non-negative value, and set constant quality value as a double floating point value in

units.

The value sets the quality value used by libfaac. A reasonable range for the option value is [10-500], the higher the value the higher the quality.

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

Examples

*

Use ffmpeg to convert an audio file to

ABR 128

kbps

AAC

in an M4A (

MP4

) container:

        ffmpeg -i input.wav -codec:a libfaac -b:a 128k -output.m4a

*

Use ffmpeg to convert an audio file to

VBR AAC,

using the

LTP AAC

profile:

        ffmpeg -i input.wav -c:a libfaac -profile:a aac_ltp -q:a 100 output.m4a

libfdk_aac

libfdk-aac

AAC

(Advanced Audio Coding) encoder wrapper.

The libfdk-aac library is based on the Fraunhofer

FDK AAC

code from the Android project.

Requires the presence of the libfdk-aac headers and library during configuration. You need to explicitly configure the build with "--enable-libfdk-aac". The library is also incompatible with

GPL,

so if you allow the use of

GPL,

you should configure with "--enable-gpl --enable-nonfree --enable-libfdk-aac".

This encoder is considered to be of higher quality with respect to both the native experimental FFmpeg

AAC

encoder and libfaac.

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 <sourceforge.net/p/opencore-amr/fdk-aac>.

Options

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

b

Set bit rate in bits/s. If the bitrate is not explicitly specified, it is automatically set to a suitable value depending on the selected profile.

In case

VBR

mode is enabled the option is ignored.

ar

Set audio sampling rate (in Hz).

channels

Set the number of audio channels.

flags +qscale

Enable fixed quality,

VBR

(Variable Bit Rate) mode. Note that

VBR

is implicitly enabled when the vbr value is positive.

cutoff

Set cutoff frequency. If not specified (or explicitly set to 0) it will use a value automatically computed by the library. Default value is 0.

profile

Set audio profile.

The following profiles are recognized:

aac_low: Low Complexity
AAC
(
LC
)
aac_he: High Efficiency
AAC
(HE-AAC)
aac_he_v2: High Efficiency
AAC
version 2 (HE-AACv2)
aac_ld: Low Delay
AAC
(
LD
)
aac_eld: Enhanced Low Delay
AAC
(
ELD
)

: If not specified it is set to aac_low.

The following are private options of the libfdk_aac encoder.

afterburner

Enable afterburner feature if set to 1, disabled if set to 0. This improves the quality but also the required processing power.

Default value is 1.

eld_sbr

Enable

SBR

(Spectral Band Replication) for

ELD

if set to 1, disabled if set to 0.

Default value is 0.

signaling

Set

SBR/PS

signaling style.

It can assume one of the following values:

default: choose signaling implicitly (explicit hierarchical by default, implicit if global header is disabled)
implicit: implicit backwards compatible signaling
explicit_sbr: explicit
SBR,
implicit
PS
signaling
explicit_hierarchical: explicit hierarchical signaling

: Default value is default.

latm

Output

LATM/LOAS

encapsulated data if set to 1, disabled if set to 0.

Default value is 0.

header_period

Set StreamMuxConfig and

PCE

repetition period (in frames) for sending in-band configuration buffers within

LATM/LOAS

transport layer.

Must be a 16-bits non-negative integer.

Default value is 0.

vbr

Set

VBR

mode, from 1 to 5. 1 is lowest quality (though still pretty good) and 5 is highest quality. A value of 0 will disable

VBR,

and

CBR

(Constant Bit Rate) is enabled.

Currently only the aac_low profile supports

VBR

encoding.

VBR

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

1: 32 kbps/channel
2: 40 kbps/channel
3: 48-56 kbps/channel
4: 64 kbps/channel
5: about 80-96 kbps/channel

: Default value is 0.

Examples

*

Use ffmpeg to convert an audio file to

VBR AAC

in an M4A (

MP4

) container:

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

*

Use ffmpeg to convert an audio file to

CBR

64k kbps

AAC,

using the High-Efficiency

AAC

profile:

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

libmp3lame

LAME

(Lame Ain't an

MP3

Encoder)

MP3

encoder wrapper.

Requires the presence of the libmp3lame headers and library during configuration. You need to explicitly configure the build with "--enable-libmp3lame".

See libshine for a fixed-point

MP3

encoder, although with a lower quality.

Options

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

b (-b): Set bitrate expressed in bits/s for
CBR
or
ABR. LAME
"bitrate" is expressed in kilobits/s.
q (-V): Set constant quality setting for
VBR.
This option is valid only using the ffmpeg command-line tool. For library interface users, use global_quality.
compression_level (-q): Set algorithm quality. Valid arguments are integers in the 0-9 range, with 0 meaning highest quality but slowest, and 9 meaning fastest while producing the worst quality.
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).

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 <sourceforge.net/projects/libshine-fxp>. We only support the updated fork by the Savonet/Liquidsoap project at <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".

libtwolame

TwoLAME

MP2

encoder wrapper.

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

Options

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

b (-b)

Set bitrate expressed in bits/s for

CBR.

twolame b option is expressed in kilobits/s. Default value is 128k.

q (-V)

Set quality for experimental

VBR

support. Maximum value range is from -50 to 50, useful range is from -10 to 10. The higher the value, the better the quality. This option is valid only using the ffmpeg command-line tool. For library interface users, use global_quality.

mode (--mode)

Set the mode of the resulting audio. Possible values:

auto: Choose mode automatically based on the input. This is the default.
stereo: Stereo
joint_stereo: Joint stereo
dual_channel: Dual channel
mono: Mono

psymodel (--psyc-mode)

Set psychoacoustic model to use in encoding. The argument must be an integer between -1 and 4, inclusive. The higher the value, the better the quality. The default value is 3.

energy_levels (--energy)

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

error_protection (--protect)

Enable

CRC

error protection when set to 1. The default value is 0 (disabled).

copyright (--copyright)

Set

MPEG

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

original (--original)

Set

MPEG

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

libvo-aacenc

VisualOn

AAC

encoder.

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

This encoder is considered to be worse than the native experimental FFmpeg

AAC

encoder, according to multiple sources.

Options

The VisualOn

AAC

encoder only support encoding AAC-LC and up to 2 channels. It is also CBR-only.

b: Set bit rate in bits/s.

libvo-amrwbenc

VisualOn Adaptive Multi-Rate Wideband encoder.

Requires the presence of the libvo-amrwbenc headers and library during configuration. You need to explicitly configure the build with "--enable-libvo-amrwbenc --enable-version3".

This is a mono-only encoder. Officially it only supports 16000Hz sample rate, but you can override it by setting strict to unofficial or lower.

Options

b

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

6600
8850
12650
14250
15850
18250
19850
23050
23850

dtx

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

libopus

libopus Opus Interactive Audio Codec encoder wrapper.

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

Option Mapping

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

b (bitrate)

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

vbr (vbr, hard-cbr, and cvbr)

Set

VBR

mode. The FFmpeg vbr option has the following valid arguments, with the their opusenc equivalent options in parentheses:

off (hard-cbr): Use constant bit rate encoding.
on (vbr): Use variable bit rate encoding (the default).
constrained (cvbr): Use constrained variable bit rate encoding.

compression_level (comp)

Set encoding algorithm complexity. Valid options are integers in the 0-10 range. 0 gives the fastest encodes but lower quality, while 10 gives the highest quality but slowest encoding. The default is 10.

frame_duration (framesize)

Set maximum frame size, or duration of a frame in milliseconds. The argument must be exactly the following: 2.5, 5, 10, 20, 40, 60. Smaller frame sizes achieve lower latency but less quality at a given bitrate. Sizes greater than 20ms are only interesting at fairly low bitrates. The default is 20ms.

packet_loss (expect-loss)

Set expected packet loss percentage. The default is 0.

application (N.A.)

Set intended application type. Valid options are listed below:

voip: Favor improved speech intelligibility.
audio: Favor faithfulness to the input (the default).
lowdelay: Restrict to only the lowest delay modes.

cutoff (N.A.)

Set cutoff bandwidth in Hz. The argument must be exactly one of the following: 4000, 6000, 8000, 12000, or 20000, corresponding to narrowband, mediumband, wideband, super wideband, and fullband respectively. The default is 0 (cutoff disabled).

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 <xiph.org/vorbis>, <wiki.xiph.org/Vorbis-tools>, and oggenc(1).

b (-b): Set bitrate expressed in bits/s for
ABR.
oggenc -b is expressed in kilobits/s.
q (-q): Set constant quality setting for
VBR.
The value should be a float number in the range of -1.0 to 10.0. The higher the value, the better the quality. The default value is 3.0.
This option is valid only using the ffmpeg command-line tool. For library interface users, use global_quality.
cutoff (--advanced-encode-option lowpass_frequency=N): Set cutoff bandwidth in Hz, a value of 0 disables cutoff. oggenc's related option is expressed in kHz. The default value is 0 (cutoff disabled).
minrate (-m): Set minimum bitrate expressed in bits/s. oggenc -m is expressed in kilobits/s.
maxrate (-M): Set maximum bitrate expressed in bits/s. oggenc -M is expressed in kilobits/s. This only has effect on
ABR
mode.
iblock (--advanced-encode-option impulse_noisetune=N): Set noise floor bias for impulse blocks. The value is a float number from -15.0 to 0.0. A negative bias instructs the encoder to pay special attention to the crispness of transients in the encoded audio. The tradeoff for better transient response is a higher bitrate.

libwavpack

A wrapper providing WavPack encoding through libwavpack.

Only lossless mode using 32-bit integer samples is supported currently.

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

Note that a libavcodec-native encoder for the WavPack codec exists so users can encode audios with this codec without using this encoder. See wavpackenc.

Options

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

frame_size (--blocksize)

Default is 32768.

compression_level

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

0 (-f): Fast mode.
1: Normal (default) settings.
2 (-h): High quality.
3 (-hh): Very high quality.
4-8 (-hh -x
EXTRAPROC
): Same as 3, but with extra processing enabled.
4 is the same as -x2 and 8 is the same as -x6.

wavpack

WavPack lossless audio encoder.

This is a libavcodec-native WavPack encoder. There is also an encoder based on libwavpack, but there is virtually no reason to use that encoder.

VIDEO ENCODERS

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

jpeg2000

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

Options

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

snow

Options

iterative_dia_size: dia size for the iterative motion estimation

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 <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

units by dividing it by "FF_QP2LAMBDA", clipped in the [0 - 10] range, and then multiplied by 6.3 to get a value in the native libtheora range [0-63]. A higher value corresponds to a higher quality.

q

Enable

VBR

mode when set to a non-negative value, and set constant quality value as a double floating point value in

units.

The value is clipped in the [0-10] range, and then multiplied by 6.3 to get a value in the native libtheora range [0-63].

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

Examples

*

Set maximum constant quality (

VBR

) encoding with ffmpeg:

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

*

Use ffmpeg to convert a

CBR 1000

kbps Theora video stream:

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

libvpx

VP8/VP9

format supported through libvpx.

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

Options

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

To reduce the duplication of documentation, only the private options and some others requiring special attention are documented here. For the documentation of the undocumented generic options, see the Codec Options chapter.

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

API

documentation.

b (target-bitrate)

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

g (kf-max-dist)

keyint_min (kf-min-dist)

qmin (min-q)

qmax (max-q)

bufsize (buf-sz, buf-optimal-sz)

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

rc_init_occupancy (buf-initial-sz)

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

undershoot-pct

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

overshoot-pct

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

skip_threshold (drop-frame)

qcomp (bias-pct)

maxrate (maxsection-pct)

Set

GOP

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

minrate (minsection-pct)

Set

GOP

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

minrate, maxrate, b end-usage=cbr

"(minrate == maxrate == bitrate)".

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

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).
arnr-max-frames: Set altref noise reduction max frame count.
arnr-type: Set altref noise reduction filter type: backward, forward, centered.
arnr-strength: Set altref noise reduction filter strength.
rc-lookahead, lag-in-frames (lag-in-frames): Set number of frames to look ahead for frametype and ratecontrol.

error-resilient

Enable error resiliency features.

VP9-specific options

lossless

Enable lossless mode.

tile-columns

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

tile-rows

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

frame-parallel

Enable frame parallel decodability features.

aq-mode

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

colorspace color-space

Set input color space. The

VP9

bitstream supports signaling the following colorspaces:

rgb sRGB
bt709 bt709
unspecified unknown
bt470bg bt601
smpte170m smpte170
smpte240m smpte240
bt2020_ncl bt2020

For more information about libvpx see: <www.webmproject.org>

libwebp

libwebp WebP Image encoder wrapper

libwebp is Google's official encoder for WebP images. It can encode in either lossy or lossless mode. Lossy images are essentially a wrapper around a

VP8

frame. Lossless images are a separate codec developed by Google.

Pixel Format

Currently, libwebp only supports

YUV420

for lossy and

RGB

for lossless due to limitations of the format and libwebp. Alpha is supported for either mode. Because of

API

limitations, if

RGB

is passed in when encoding lossy or

YUV

is passed in for encoding lossless, the pixel format will automatically be converted using functions from libwebp. This is not ideal and is done only for convenience.

Options

-lossless boolean

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

-compression_level integer

For lossy, this is a quality/speed tradeoff. Higher values give better quality for a given size at the cost of increased encoding time. For lossless, this is a size/speed tradeoff. Higher values give smaller size at the cost of increased encoding time. More specifically, it controls the number of extra algorithms and compression tools used, and varies the combination of these tools. This maps to the method option in libwebp. The valid range is 0 to 6. Default is 4.

-qscale float

For lossy encoding, this controls image quality, 0 to 100. For lossless encoding, this controls the effort and time spent at compressing more. The default value is 75. Note that for usage via libavcodec, this option is called global_quality and must be multiplied by

FF_QP2LAMBDA

-preset type

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

none: Do not use a preset.
default: Use the encoder default.
picture: Digital picture, like portrait, inner shot
photo: Outdoor photograph, with natural lighting
drawing: Hand or line drawing, with high-contrast details
icon: Small-sized colorful images
text: Text-like

libx264, libx264rgb

x264 H.264/MPEG-4

AVC

encoder wrapper.

This encoder requires the presence of the libx264 headers and library during configuration. You need to explicitly configure the build with "--enable-libx264".

libx264 supports an impressive number of features, including 8x8 and 4x4 adaptive spatial transform, adaptive B-frame placement,

CAVLC/CABAC

entropy coding, interlacing (

MBAFF

), lossless mode, psy optimizations for detail retention (adaptive quantization, psy-RD, psy-trellis).

Many libx264 encoder options are mapped to FFmpeg global codec options, while unique encoder options are provided through private options. Additionally the x264opts and x264-params private options allows one to pass a list of key=value tuples as accepted by the libx264 "x264_param_parse" function.

The x264 project website is at <www.videolan.org/developers/x264.html>.

The libx264rgb encoder is the same as libx264, except it accepts packed

RGB

pixel formats as input instead of

YUV.

Supported Pixel Formats

x264 supports 8- to 10-bit color spaces. The exact bit depth is controlled at x264's configure time. FFmpeg only supports one bit depth in one particular build. In other words, it is not possible to build one FFmpeg with multiple versions of x264 with different bit depths.

Options

The following options are supported by the libx264 wrapper. The x264-equivalent options or values are listed in parentheses for easy migration.

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

b (bitrate)

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

bf (bframes)

g (keyint)

qmin (qpmin)

Minimum quantizer scale.

qmax (qpmax)

Maximum quantizer scale.

qdiff (qpstep)

Maximum difference between quantizer scales.

qblur (qblur)

Quantizer curve blur

qcomp (qcomp)

Quantizer curve compression factor

refs (ref)

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

sc_threshold (scenecut)

Sets the threshold for the scene change detection.

trellis (trellis)

Performs Trellis quantization to increase efficiency. Enabled by default.

nr (nr)

me_range (merange)

Maximum range of the motion search in pixels.

me_method (me)

Set motion estimation method. Possible values in the decreasing order of speed:

dia (dia)
epzs (dia): Diamond search with radius 1 (fastest). epzs is an alias for dia.
hex (hex): Hexagonal search with radius 2.
umh (umh): Uneven multi-hexagon search.
esa (esa): Exhaustive search.
tesa (tesa): Hadamard exhaustive search (slowest).

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 comparation algorithm. Possible values:

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

threads (threads)

Number of encoding threads.

thread_type

Set multithreading technique. Possible values:

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

flags

Set encoding flags. It can be used to disable closed

GOP

and enable open

GOP

by setting it to "-cgop". The result is similar to the behavior of x264's --open-gop option.

rc_init_occupancy (vbv-init)

preset (preset)

Set the encoding preset.

tune (tune)

Set tuning of the encoding params.

profile (profile)

Set profile restrictions.

fastfirstpass

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

crf (crf)

Set the quality for constant quality mode.

crf_max (crf-max)

CRF

mode, prevents

VBV

from lowering quality beyond this point.

qp (qp)

Set constant quantization rate control method parameter.

aq-mode (aq-mode)

Set

method. Possible values:

none (0): Disabled.
variance (1): Variance
AQ
(complexity mask).
autovariance (2): Auto-variance
AQ
(experimental).

aq-strength (aq-strength)

Set

strength, reduce blocking and blurring in flat and textured areas.

psy

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

psy-rd (psy-rd)

Set strength of psychovisual optimization, in psy-rd:psy-trellis format.

rc-lookahead (rc-lookahead)

Set number of frames to look ahead for frametype and ratecontrol.

weightb

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

weightp (weightp)

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

none (0): Disabled
simple (1): Enable only weighted refs
smart (2): Enable both weighted refs and duplicates

ssim (ssim)

Enable calculation and printing

SSIM

stats after the encoding.

intra-refresh (intra-refresh)

Enable the use of Periodic Intra Refresh instead of

IDR

frames when set to 1.

avcintra-class (class)

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

bluray-compat (bluray-compat)

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

b-bias (b-bias)

Set the influence on how often B-frames are used.

b-pyramid (b-pyramid)

Set method for keeping of some B-frames as references. Possible values:

none (none): Disabled.
strict (strict): Strictly hierarchical pyramid.
normal (normal): Non-strict (not Blu-ray compatible).

mixed-refs

Enable the use of one reference per partition, as opposed to one reference per macroblock when set to 1. When set to 0, it has the same effect as x264's --no-mixed-refs option.

8x8dct

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

fast-pskip

Enable early

SKIP

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

aud (aud)

Enable use of access unit delimiters when set to 1.

mbtree

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

deblock (deblock)

Set loop filter parameters, in alpha:beta form.

cplxblur (cplxblur)

Set fluctuations reduction in

(before curve compression).

partitions (partitions)

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

p8x8: 8x8 P-frame partition.
p4x4: 4x4 P-frame partition.
b8x8: 4x4 B-frame partition.
i8x8: 8x8 I-frame partition.
i4x4: 4x4 I-frame partition. (Enabling p4x4 requires p8x8 to be enabled. Enabling i8x8 requires adaptive spatial transform (8x8dct option) to be enabled.)
none (none): Do not consider any partitions.
all (all): Consider every partition.

direct-pred (direct)

Set direct

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 -vcodec libx264 -x264opts keyint=123:min-keyint=20 -an out.mkv

x264-params (N.A.)

Override the x264 configuration using a :-separated list of key=value parameters.

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

For example to specify libx264 encoding options with ffmpeg:

        ffmpeg -i INPUT -c:v libx264 -x264-params level=30:bframes=0:weightp=0:\
        cabac=0:ref=1:vbv-maxrate=768:vbv-bufsize=2000:analyse=all:me=umh:\
        no-fast-pskip=1:subq=6:8x8dct=0:trellis=0 OUTPUT

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

libx265

x265 H.265/HEVC encoder wrapper.

This encoder requires the presence of the libx265 headers and library during configuration. You need to explicitly configure the build with --enable-libx265.

Options

preset

Set the x265 preset.

tune

Set the x265 tune parameter.

x265-params

Set x265 options using a list of key=value couples separated by ``:''. See x265 --help for a list of options.

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

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

libxvid

Xvid

MPEG-4

Part 2 encoder wrapper.

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

The native "mpeg4" encoder supports the

MPEG-4

Part 2 format, so users can encode to this format without this library.

Options

The following options are supported by the libxvid wrapper. Some of the following options are listed but are not documented, and correspond to shared codec options. See the Codec Options chapter for their documentation. The other shared options which are not listed have no effect for the libxvid encoder.

b

g

qmin

qmax

mpeg_quant

threads

bf

b_qfactor

b_qoffset

flags

Set specific encoding flags. Possible values:

mv4: Use four motion vector by macroblock.
aic: Enable high quality
AC
prediction.
gray: Only encode grayscale.
gmc: Enable the use of global motion compensation (
GMC
).
qpel: Enable quarter-pixel motion compensation.
cgop: Enable closed
GOP.
global_header: Place global headers in extradata instead of every keyframe.

trellis

me_method

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

zero: Use no motion estimation (default).
phods
x1
log: Enable advanced diamond zonal search for 16x16 blocks and half-pixel refinement for 16x16 blocks. x1 and log are aliases for phods.
epzs: Enable all of the things described above, plus advanced diamond zonal search for 8x8 blocks, half-pixel refinement for 8x8 blocks, and motion estimation on chroma planes.
full: Enable all of the things described above, plus extended 16x16 and 8x8 blocks search.

mbd

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

simple: Use macroblock comparing function algorithm (default).
bits: Enable rate distortion-based half pixel and quarter pixel refinement for 16x16 blocks.
rd: Enable all of the things described above, plus rate distortion-based half pixel and quarter pixel refinement for 8x8 blocks, and rate distortion-based search using square pattern.

lumi_aq

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

variance_aq

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

When combined with lumi_aq, the resulting quality will not be better than any of the two specified individually. In other words, the resulting quality will be the worse one of the two effects.

ssim

Set structural similarity (

SSIM

) displaying method. Possible values:

off

Disable displaying of

SSIM

information.

avg

Output average

SSIM

at the end of encoding to stdout. The format of showing the average

SSIM

is:

        Average SSIM: %f

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

frame

Output both per-frame

SSIM

data during encoding and average

SSIM

at the end of encoding to stdout. The format of per-frame information is:

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

For users who are not familiar with C, %1.3f means a float number rounded to 3 digits after the dot (e.g. 0.932).

ssim_acc

Set

SSIM

accuracy. Valid options are integers within the range of 0-4, while 0 gives the most accurate result and 4 computes the fastest.

mpeg2

MPEG-2

video encoder.

Options

seq_disp_ext integer

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

-1
auto: Decide automatically to write it or not (this is the default) by checking if the data to be written is different from the default or unspecified values.
0
never: Never write it.
1
always: Always write it.

png

PNG

image encoder.

Private options

dpi integer: Set physical density of pixels, in dots per inch, unset by default
dpm integer: Set physical density of pixels, in dots per meter, unset by default

ProRes

Apple ProRes encoder.

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

Private Options for prores-ks

profile integer

Select the ProRes profile to encode

proxy
lt
standard
hq
4444

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

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.

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.
threads: Set number of encoding threads.
kvazaar-params: Set kvazaar parameters as a list of name=value pairs separated by commas (,). See kvazaar documentation for a list of options.

SUBTITLES ENCODERS

dvdsub

This codec encodes the bitmap subtitle format that is used in DVDs. Typically they are stored in

VOBSUB

file pairs (*.idx + *.sub), and they can also be used in Matroska files.

Options

even_rows_fix: When set to 1, enable a work-around that makes the number of pixel rows even in all subtitles. This fixes a problem with some players that cut off the bottom row if the number is odd. The work-around just adds a fully transparent row if needed. The overhead is low, typically one byte per subtitle on average.
By default, this work-around is disabled.

AUTHORS

The FFmpeg developers.

For details about the authorship, see the Git history of the project (git://source.ffmpeg.org/ffmpeg e.g. by typing the command git log in the FFmpeg source directory, or browsing the online repository at <source.ffmpeg.org>.

Maintainers for the specific components are listed in the file

MAINTAINERS

in the source code tree.

ffmpeg-codecs • man page

ffmpeg-codecs • man page

ffmpeg-codecs (1)

Leading comments

NAME

DESCRIPTION

CODEC OPTIONS

DECODERS

VIDEO DECODERS

hevc

rawvideo

AUDIO DECODERS

ac3

flac

ffwavesynth

libcelt

libgsm

libilbc

libopencore-amrnb

libopencore-amrwb

libopus

SUBTITLES DECODERS

dvbsub

dvdsub

libzvbi-teletext

ENCODERS

AUDIO ENCODERS

aac

ac3 and ac3_fixed

flac

libfaac

libfdk_aac

libmp3lame

libopencore-amrnb

libshine

libtwolame

libvo-aacenc

libvo-amrwbenc

libopus

libvorbis

libwavpack

wavpack

VIDEO ENCODERS

jpeg2000

snow

libtheora

libvpx

libwebp

libx264, libx264rgb

libx265

libxvid

mpeg2

png

ProRes

libkvazaar

SUBTITLES ENCODERS

dvdsub

SEE ALSO

AUTHORS

Installed via

Man Section

extra • Version

References

Referenced By