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PROGRAM:
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 DC 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 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
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 QP factor between P and I frames.
i_qoffset float (encoding,video)
Set QP 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.
See also libfdk_aac.
Options
b Set bit rate in bits/s. Setting this automatically activates constant bit rate (CBR)
mode.
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.
stereo_mode
Set stereo encoding mode. Possible values:
auto
Automatically selected by the encoder.
ms_off
Disable middle/side encoding. This is the default.
ms_force
Force middle/side encoding.
aac_coder
Set AAC encoder coding method. Possible values:
faac
FAAC-inspired method.
This method is a simplified reimplementation of the method used in FAAC, which
sets thresholds proportional to the band energies, and then decreases all the
thresholds with quantizer steps to find the appropriate quantization with
distortion below threshold band by band.
The quality of this method is comparable to the two loop searching method
described below, but somewhat a little better and slower.
anmr
Average noise to mask ratio (ANMR) trellis-based solution.
This has a theoretic best quality out of all the coding methods, but at the cost
of the slowest speed.
twoloop
Two loop searching (TLS) method.
This method first sets quantizers depending on band thresholds and then tries to
find an optimal combination by adding or subtracting a specific value from all
quantizers and adjusting some individual quantizer a little.
This method produces similar quality with the FAAC method and is the default.
fast
Constant quantizer method.
This method sets a constant quantizer for all bands. This is the fastest of all
the methods, yet produces the worst quality.
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.
*<<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
-center_mixlev level
Center Mix Level. The amount of gain the decoder should apply to the center channel
when downmixing to stereo. This field will only be written to the bitstream if a
center channel is present. The value is specified as a scale factor. There are 3 valid
values:
0.707
Apply -3dB gain
0.595
Apply -4.5dB gain (default)
0.500
Apply -6dB gain
-surround_mixlev level
Surround Mix Level. The amount of gain the decoder should apply to the surround
channel(s) when downmixing to stereo. This field will only be written to the bitstream
if one or more surround channels are present. The value is specified as a scale
factor. There are 3 valid values:
0.707
Apply -3dB gain
0.500
Apply -6dB gain (default)
0.000
Silence Surround Channel(s)
Audio Production Information
Audio Production Information is optional information describing the mixing environment.
Either none or both of the fields are written to the bitstream.
-mixing_level number
Mixing Level. Specifies peak sound pressure level (SPL) in the production environment
when the mix was mastered. Valid values are 80 to 111, or -1 for unknown or not
indicated. The default value is -1, but that value cannot be used if the Audio
Production Information is written to the bitstream. Therefore, if the "room_type"
option is not the default value, the "mixing_level" option must not be -1.
-room_type type
Room Type. Describes the equalization used during the final mixing session at the
studio or on the dubbing stage. A large room is a dubbing stage with the industry
standard X-curve equalization; a small room has flat equalization. This field will
not be written to the bitstream if both the "mixing_level" option and the "room_type"
option have the default values.
0
notindicated
Not Indicated (default)
1
large
Large Room
2
small
Small Room
Other Metadata Options
-copyright boolean
Copyright Indicator. Specifies whether a copyright exists for this audio.
0
off No Copyright Exists (default)
1
on Copyright Exists
-dialnorm value
Dialogue Normalization. Indicates how far the average dialogue level of the program is
below digital 100% full scale (0 dBFS). This parameter determines a level shift during
audio reproduction that sets the average volume of the dialogue to a preset level. The
goal is to match volume level between program sources. A value of -31dB will result in
no volume level change, relative to the source volume, during audio reproduction.
Valid values are whole numbers in the range -31 to -1, with -31 being the default.
-dsur_mode mode
Dolby Surround Mode. Specifies whether the stereo signal uses Dolby Surround (Pro
Logic). This field will only be written to the bitstream if the audio stream is
stereo. Using this option does NOT mean the encoder will actually apply Dolby Surround
processing.
0
notindicated
Not Indicated (default)
1
off Not Dolby Surround Encoded
2
on Dolby Surround Encoded
-original boolean
Original Bit Stream Indicator. Specifies whether this audio is from the original
source and not a copy.
0
off Not Original Source
1
on Original Source (default)
Extended Bitstream Information
The extended bitstream options are part of the Alternate Bit Stream Syntax as specified in
Annex D of the A/52:2010 standard. It is grouped into 2 parts. If any one parameter in a
group is specified, all values in that group will be written to the bitstream. Default
values are used for those that are written but have not been specified. If the mixing
levels are written, the decoder will use these values instead of the ones specified in the
"center_mixlev" and "surround_mixlev" options if it supports the Alternate Bit Stream
Syntax.
Extended Bitstream Information - Part 1
-dmix_mode mode
Preferred Stereo Downmix Mode. Allows the user to select either Lt/Rt (Dolby Surround)
or Lo/Ro (normal stereo) as the preferred stereo downmix mode.
0
notindicated
Not Indicated (default)
1
ltrt
Lt/Rt Downmix Preferred
2
loro
Lo/Ro Downmix Preferred
-ltrt_cmixlev level
Lt/Rt Center Mix Level. The amount of gain the decoder should apply to the center
channel when downmixing to stereo in Lt/Rt mode.
1.414
Apply +3dB gain
1.189
Apply +1.5dB gain
1.000
Apply 0dB gain
0.841
Apply -1.5dB gain
0.707
Apply -3.0dB gain
0.595
Apply -4.5dB gain (default)
0.500
Apply -6.0dB gain
0.000
Silence Center Channel
-ltrt_surmixlev level
Lt/Rt Surround Mix Level. The amount of gain the decoder should apply to the surround
channel(s) when downmixing to stereo in Lt/Rt mode.
0.841
Apply -1.5dB gain
0.707
Apply -3.0dB gain
0.595
Apply -4.5dB gain
0.500
Apply -6.0dB gain (default)
0.000
Silence Surround Channel(s)
-loro_cmixlev level
Lo/Ro Center Mix Level. The amount of gain the decoder should apply to the center
channel when downmixing to stereo in Lo/Ro mode.
1.414
Apply +3dB gain
1.189
Apply +1.5dB gain
1.000
Apply 0dB gain
0.841
Apply -1.5dB gain
0.707
Apply -3.0dB gain
0.595
Apply -4.5dB gain (default)
0.500
Apply -6.0dB gain
0.000
Silence Center Channel
-loro_surmixlev level
Lo/Ro Surround Mix Level. The amount of gain the decoder should apply to the surround
channel(s) when downmixing to stereo in Lo/Ro mode.
0.841
Apply -1.5dB gain
0.707
Apply -3.0dB gain
0.595
Apply -4.5dB gain
0.500
Apply -6.0dB gain (default)
0.000
Silence Surround Channel(s)
Extended Bitstream Information - Part 2
-dsurex_mode mode
Dolby Surround EX Mode. Indicates whether the stream uses Dolby Surround EX (7.1
matrixed to 5.1). Using this option does NOT mean the encoder will actually apply
Dolby Surround EX processing.
0
notindicated
Not Indicated (default)
1
on Dolby Surround EX Off
2
off Dolby Surround EX On
-dheadphone_mode mode
Dolby Headphone Mode. Indicates whether the stream uses Dolby Headphone encoding
(multi-channel matrixed to 2.0 for use with headphones). Using this option does NOT
mean the encoder will actually apply Dolby Headphone processing.
0
notindicated
Not Indicated (default)
1
on Dolby Headphone Off
2
off Dolby Headphone On
-ad_conv_type type
A/D Converter Type. Indicates whether the audio has passed through HDCD A/D
conversion.
0
standard
Standard A/D Converter (default)
1
hdcd
HDCD A/D Converter
Other AC-3 Encoding Options
-stereo_rematrixing boolean
Stereo Rematrixing. Enables/Disables use of rematrixing for stereo input. This is an
optional AC-3 feature that increases quality by selectively encoding the left/right
channels as mid/side. This option is enabled by default, and it is highly recommended
that it be left as enabled except for testing purposes.
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
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 <http://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).
If 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 QP 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 QP 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 QP 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
<http://sourceforge.net/p/opencore-amr/fdk-aac/>.
Options
The following options are mapped on the shared FFmpeg codec options.
b Set bit rate in bits/s. If the bitrate is not explicitly specified, it is
automatically set to a suitable value depending on the selected profile.
In case VBR mode is enabled the option is ignored.
ar Set audio sampling rate (in Hz).
channels
Set the number of audio channels.
flags +qscale
Enable fixed quality, VBR (Variable Bit Rate) mode. Note that VBR is implicitly
enabled when the vbr value is positive.
cutoff
Set cutoff frequency. If not specified (or explicitly set to 0) it will use a value
automatically computed by the library. Default value is 0.
profile
Set audio profile.
The following profiles are recognized:
aac_low
Low Complexity AAC (LC)
aac_he
High Efficiency AAC (HE-AAC)
aac_he_v2
High Efficiency AAC version 2 (HE-AACv2)
aac_ld
Low Delay AAC (LD)
aac_eld
Enhanced Low Delay AAC (ELD)
If not specified it is set to aac_low.
The following are private options of the libfdk_aac encoder.
afterburner
Enable afterburner feature if set to 1, disabled if set to 0. This improves the
quality but also the required processing power.
Default value is 1.
eld_sbr
Enable SBR (Spectral Band Replication) for ELD if set to 1, disabled if set to 0.
Default value is 0.
signaling
Set SBR/PS signaling style.
It can assume one of the following values:
default
choose signaling implicitly (explicit hierarchical by default, implicit if global
header is disabled)
implicit
implicit backwards compatible signaling
explicit_sbr
explicit SBR, implicit PS signaling
explicit_hierarchical
explicit hierarchical signaling
Default value is default.
latm
Output LATM/LOAS encapsulated data if set to 1, disabled if set to 0.
Default value is 0.
header_period
Set StreamMuxConfig and PCE repetition period (in frames) for sending in-band
configuration buffers within LATM/LOAS transport layer.
Must be a 16-bits non-negative integer.
Default value is 0.
vbr Set VBR mode, from 1 to 5. 1 is lowest quality (though still pretty good) and 5 is
highest quality. A value of 0 will disable VBR, and CBR (Constant Bit Rate) is
enabled.
Currently only the aac_low profile supports VBR encoding.
VBR modes 1-5 correspond to roughly the following average bit rates:
1 32 kbps/channel
2 40 kbps/channel
3 48-56 kbps/channel
4 64 kbps/channel
5 about 80-96 kbps/channel
Default value is 0.
Examples
· Use ffmpeg to convert an audio file to VBR AAC in an M4A (MP4) container:
ffmpeg -i input.wav -codec:a libfdk_aac -vbr 3 output.m4a
· Use ffmpeg to convert an audio file to CBR 64k kbps AAC, using the High-Efficiency AAC
profile:
ffmpeg -i input.wav -c:a libfdk_aac -profile:a aac_he -b:a 64k output.m4a
libmp3lame
LAME (Lame Ain't an MP3 Encoder) MP3 encoder wrapper.
Requires the presence of the libmp3lame headers and library during configuration. You need
to explicitly configure the build with "--enable-libmp3lame".
See libshine for a fixed-point MP3 encoder, although with a lower quality.
Options
The following options are supported by the libmp3lame wrapper. The lame-equivalent of the
options are listed in parentheses.
b (-b)
Set bitrate expressed in bits/s for CBR or ABR. LAME "bitrate" is expressed in
kilobits/s.
q (-V)
Set constant quality setting for VBR. This option is valid only using the ffmpeg
command-line tool. For library interface users, use global_quality.
compression_level (-q)
Set algorithm quality. Valid arguments are integers in the 0-9 range, with 0 meaning
highest quality but slowest, and 9 meaning fastest while producing the worst quality.
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
<http://sourceforge.net/projects/libshine-fxp/>. We only support the updated fork by the
Savonet/Liquidsoap project at <https://github.com/savonet/shine>.
Requires the presence of the libshine headers and library during configuration. You need
to explicitly configure the build with "--enable-libshine".
See also libmp3lame.
Options
The following options are supported by the libshine wrapper. The shineenc-equivalent of
the options are listed in parentheses.
b (-b)
Set bitrate expressed in bits/s for CBR. shineenc -b option is expressed in
kilobits/s.
libtwolame
TwoLAME MP2 encoder wrapper.
Requires the presence of the libtwolame headers and library during configuration. You need
to explicitly configure the build with "--enable-libtwolame".
Options
The following options are supported by the libtwolame wrapper. The twolame-equivalent
options follow the FFmpeg ones and are in parentheses.
b (-b)
Set bitrate expressed in bits/s for CBR. twolame b option is expressed in kilobits/s.
Default value is 128k.
q (-V)
Set quality for experimental VBR support. Maximum value range is from -50 to 50,
useful range is from -10 to 10. The higher the value, the better the quality. This
option is valid only using the ffmpeg command-line tool. For library interface users,
use global_quality.
mode (--mode)
Set the mode of the resulting audio. Possible values:
auto
Choose mode automatically based on the input. This is the default.
stereo
Stereo
joint_stereo
Joint stereo
dual_channel
Dual channel
mono
Mono
psymodel (--psyc-mode)
Set psychoacoustic model to use in encoding. The argument must be an integer between
-1 and 4, inclusive. The higher the value, the better the quality. The default value
is 3.
energy_levels (--energy)
Enable energy levels extensions when set to 1. The default value is 0 (disabled).
error_protection (--protect)
Enable CRC error protection when set to 1. The default value is 0 (disabled).
copyright (--copyright)
Set MPEG audio copyright flag when set to 1. The default value is 0 (disabled).
original (--original)
Set MPEG audio original flag when set to 1. The default value is 0 (disabled).
libvo-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 <http://xiph.org/vorbis/>,
<http://wiki.xiph.org/Vorbis-tools>, and oggenc(1).
b (-b)
Set bitrate expressed in bits/s for ABR. oggenc -b is expressed in kilobits/s.
q (-q)
Set constant quality setting for VBR. The value should be a float number in the range
of -1.0 to 10.0. The higher the value, the better the quality. The default value is
3.0.
This option is valid only using the ffmpeg command-line tool. For library interface
users, use global_quality.
cutoff (--advanced-encode-option lowpass_frequency=N)
Set cutoff bandwidth in Hz, a value of 0 disables cutoff. oggenc's related option is
expressed in kHz. The default value is 0 (cutoff disabled).
minrate (-m)
Set minimum bitrate expressed in bits/s. oggenc -m is expressed in kilobits/s.
maxrate (-M)
Set maximum bitrate expressed in bits/s. oggenc -M is expressed in kilobits/s. This
only has effect on ABR mode.
iblock (--advanced-encode-option impulse_noisetune=N)
Set noise floor bias for impulse blocks. The value is a float number from -15.0 to
0.0. A negative bias instructs the encoder to pay special attention to the crispness
of transients in the encoded audio. The tradeoff for better transient response is a
higher bitrate.
libwavpack
A wrapper providing WavPack encoding through libwavpack.
Only lossless mode using 32-bit integer samples is supported currently.
Requires the presence of the libwavpack headers and library during configuration. You need
to explicitly configure the build with "--enable-libwavpack".
Note that a libavcodec-native encoder for the WavPack codec exists so users can encode
audios with this codec without using this encoder. See wavpackenc.
Options
wavpack command line utility's corresponding options are listed in parentheses, if any.
frame_size (--blocksize)
Default is 32768.
compression_level
Set speed vs. compression tradeoff. Acceptable arguments are listed below:
0 (-f)
Fast mode.
1 Normal (default) settings.
2 (-h)
High quality.
3 (-hh)
Very high quality.
4-8 (-hh -xEXTRAPROC)
Same as 3, but with extra processing enabled.
4 is the same as -x2 and 8 is the same as -x6.
wavpack
WavPack lossless audio encoder.
This is a libavcodec-native WavPack encoder. There is also an encoder based on libwavpack,
but there is virtually no reason to use that encoder.
See also libwavpack.
Options
The equivalent options for wavpack command line utility are listed in parentheses.
Shared options
The following shared options are effective for this encoder. Only special notes about this
particular encoder will be documented here. For the general meaning of the options, see
the Codec Options chapter.
frame_size (--blocksize)
For this encoder, the range for this option is between 128 and 131072. Default is
automatically decided based on sample rate and number of channel.
For the complete formula of calculating default, see libavcodec/wavpackenc.c.
compression_level (-f, -h, -hh, and -x)
This option's syntax is consistent with libwavpack's.
Private options
joint_stereo (-j)
Set whether to enable joint stereo. Valid values are:
on (1)
Force mid/side audio encoding.
off (0)
Force left/right audio encoding.
auto
Let the encoder decide automatically.
optimize_mono
Set whether to enable optimization for mono. This option is only effective for non-
mono streams. Available values:
on enabled
off disabled
VIDEO ENCODERS
A description of some of the currently available video encoders follows.
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 <http://www.theora.org/>.
Options
The following global options are mapped to internal libtheora options which affect the
quality and the bitrate of the encoded stream.
b Set the video bitrate in bit/s for CBR (Constant Bit Rate) mode. In case VBR
(Variable Bit Rate) mode is enabled this option is ignored.
flags
Used to enable constant quality mode (VBR) encoding through the qscale flag, and to
enable the "pass1" and "pass2" modes.
g Set the GOP size.
global_quality
Set the global quality as an integer in lambda units.
Only relevant when VBR mode is enabled with "flags +qscale". The value is converted to
QP units by dividing it by "FF_QP2LAMBDA", clipped in the [0 - 10] range, and then
multiplied by 6.3 to get a value in the native libtheora range [0-63]. A higher value
corresponds to a higher quality.
q Enable VBR mode when set to a non-negative value, and set constant quality value as a
double floating point value in QP units.
The value is clipped in the [0-10] range, and then multiplied by 6.3 to get a value in
the native libtheora range [0-63].
This option is valid only using the ffmpeg command-line tool. For library interface
users, use global_quality.
Examples
· Set maximum constant quality (VBR) encoding with ffmpeg:
ffmpeg -i INPUT -codec:v libtheora -q:v 10 OUTPUT.ogg
· Use ffmpeg to convert a CBR 1000 kbps Theora video stream:
ffmpeg -i INPUT -codec:v libtheora -b:v 1000k OUTPUT.ogg
libvpx
VP8/VP9 format supported through libvpx.
Requires the presence of the libvpx headers and library during configuration. You need to
explicitly configure the build with "--enable-libvpx".
Options
The following options are supported by the libvpx wrapper. The vpxenc-equivalent options
or values are listed in parentheses for easy migration.
To reduce the duplication of documentation, only the private options and some others
requiring special attention are documented here. For the documentation of the undocumented
generic options, see the Codec Options chapter.
To get more documentation of the libvpx options, invoke the command ffmpeg -h
encoder=libvpx, ffmpeg -h encoder=libvpx-vp9 or vpxenc --help. Further information is
available in the libvpx API documentation.
b (target-bitrate)
Set bitrate in bits/s. Note that FFmpeg's b option is expressed in bits/s, while
vpxenc's target-bitrate is in kilobits/s.
g (kf-max-dist)
keyint_min (kf-min-dist)
qmin (min-q)
qmax (max-q)
bufsize (buf-sz, buf-optimal-sz)
Set ratecontrol buffer size (in bits). Note vpxenc's options are specified in
milliseconds, the libvpx wrapper converts this value as follows: "buf-sz = bufsize *
1000 / bitrate", "buf-optimal-sz = bufsize * 1000 / bitrate * 5 / 6".
rc_init_occupancy (buf-initial-sz)
Set number of bits which should be loaded into the rc buffer before decoding starts.
Note vpxenc's option is specified in milliseconds, the libvpx wrapper converts this
value as follows: "rc_init_occupancy * 1000 / bitrate".
undershoot-pct
Set datarate undershoot (min) percentage of the target bitrate.
overshoot-pct
Set datarate overshoot (max) percentage of the target bitrate.
skip_threshold (drop-frame)
qcomp (bias-pct)
maxrate (maxsection-pct)
Set GOP max bitrate in bits/s. Note vpxenc's option is specified as a percentage of
the target bitrate, the libvpx wrapper converts this value as follows: "(maxrate * 100
/ bitrate)".
minrate (minsection-pct)
Set GOP min bitrate in bits/s. Note vpxenc's option is specified as a percentage of
the target bitrate, the libvpx wrapper converts this value as follows: "(minrate * 100
/ bitrate)".
minrate, maxrate, b end-usage=cbr
"(minrate == maxrate == bitrate)".
crf (end-usage=cq, cq-level)
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: <http://www.webmproject.org/>
libwebp
libwebp WebP Image encoder wrapper
libwebp is Google's official encoder for WebP images. It can encode in either lossy or
lossless mode. Lossy images are essentially a wrapper around a VP8 frame. Lossless images
are a separate codec developed by Google.
Pixel Format
Currently, libwebp only supports YUV420 for lossy and RGB for lossless due to limitations
of the format and libwebp. Alpha is supported for either mode. Because of API
limitations, if RGB is passed in when encoding lossy or YUV is passed in for encoding
lossless, the pixel format will automatically be converted using functions from libwebp.
This is not ideal and is done only for convenience.
Options
-lossless boolean
Enables/Disables use of lossless mode. Default is 0.
-compression_level integer
For lossy, this is a quality/speed tradeoff. Higher values give better quality for a
given size at the cost of increased encoding time. For lossless, this is a size/speed
tradeoff. Higher values give smaller size at the cost of increased encoding time. More
specifically, it controls the number of extra algorithms and compression tools used,
and varies the combination of these tools. This maps to the method option in libwebp.
The valid range is 0 to 6. Default is 4.
-qscale float
For lossy encoding, this controls image quality, 0 to 100. For lossless encoding, this
controls the effort and time spent at compressing more. The default value is 75. Note
that for usage via libavcodec, this option is called global_quality and must be
multiplied by FF_QP2LAMBDA.
-preset type
Configuration preset. This does some automatic settings based on the general type of
the image.
none
Do not use a preset.
default
Use the encoder default.
picture
Digital picture, like portrait, inner shot
photo
Outdoor photograph, with natural lighting
drawing
Hand or line drawing, with high-contrast details
icon
Small-sized colorful images
text
Text-like
libx264, libx264rgb
x264 H.264/MPEG-4 AVC encoder wrapper.
This encoder requires the presence of the libx264 headers and library during
configuration. You need to explicitly configure the build with "--enable-libx264".
libx264 supports an impressive number of features, including 8x8 and 4x4 adaptive spatial
transform, adaptive B-frame placement, CAVLC/CABAC entropy coding, interlacing (MBAFF),
lossless mode, psy optimizations for detail retention (adaptive quantization, psy-RD, psy-
trellis).
Many libx264 encoder options are mapped to FFmpeg global codec options, while unique
encoder options are provided through private options. Additionally the x264opts and
x264-params private options allows one to pass a list of key=value tuples as accepted by
the libx264 "x264_param_parse" function.
The x264 project website is at <http://www.videolan.org/developers/x264.html>.
The libx264rgb encoder is the same as libx264, except it accepts packed RGB pixel formats
as input instead of YUV.
Supported Pixel Formats
x264 supports 8- to 10-bit color spaces. The exact bit depth is controlled at x264's
configure time. FFmpeg only supports one bit depth in one particular build. In other
words, it is not possible to build one FFmpeg with multiple versions of x264 with
different bit depths.
Options
The following options are supported by the libx264 wrapper. The x264-equivalent options or
values are listed in parentheses for easy migration.
To reduce the duplication of documentation, only the private options and some others
requiring special attention are documented here. For the documentation of the undocumented
generic options, see the Codec Options chapter.
To get a more accurate and extensive documentation of the libx264 options, invoke the
command x264 --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)
In CRF mode, prevents VBV from lowering quality beyond this point.
qp (qp)
Set constant quantization rate control method parameter.
aq-mode (aq-mode)
Set AQ method. Possible values:
none (0)
Disabled.
variance (1)
Variance AQ (complexity mask).
autovariance (2)
Auto-variance AQ (experimental).
aq-strength (aq-strength)
Set AQ strength, reduce blocking and blurring in flat and textured areas.
psy Use psychovisual optimizations when set to 1. When set to 0, it has the same effect as
x264's --no-psy option.
psy-rd (psy-rd)
Set strength of psychovisual optimization, in psy-rd:psy-trellis format.
rc-lookahead (rc-lookahead)
Set number of frames to look ahead for frametype and ratecontrol.
weightb
Enable weighted prediction for B-frames when set to 1. When set to 0, it has the same
effect as x264's --no-weightb option.
weightp (weightp)
Set weighted prediction method for P-frames. Possible values:
none (0)
Disabled
simple (1)
Enable only weighted refs
smart (2)
Enable both weighted refs and duplicates
ssim (ssim)
Enable calculation and printing SSIM stats after the encoding.
intra-refresh (intra-refresh)
Enable the use of Periodic Intra Refresh instead of IDR frames when set to 1.
avcintra-class (class)
Configure the encoder to generate AVC-Intra. Valid values are 50,100 and 200
bluray-compat (bluray-compat)
Configure the encoder to be compatible with the bluray standard. It is a shorthand
for setting "bluray-compat=1 force-cfr=1".
b-bias (b-bias)
Set the influence on how often B-frames are used.
b-pyramid (b-pyramid)
Set method for keeping of some B-frames as references. Possible values:
none (none)
Disabled.
strict (strict)
Strictly hierarchical pyramid.
normal (normal)
Non-strict (not Blu-ray compatible).
mixed-refs
Enable the use of one reference per partition, as opposed to one reference per
macroblock when set to 1. When set to 0, it has the same effect as x264's
--no-mixed-refs option.
8x8dct
Enable adaptive spatial transform (high profile 8x8 transform) when set to 1. When set
to 0, it has the same effect as x264's --no-8x8dct option.
fast-pskip
Enable early SKIP detection on P-frames when set to 1. When set to 0, it has the same
effect as x264's --no-fast-pskip option.
aud (aud)
Enable use of access unit delimiters when set to 1.
mbtree
Enable use macroblock tree ratecontrol when set to 1. When set to 0, it has the same
effect as x264's --no-mbtree option.
deblock (deblock)
Set loop filter parameters, in alpha:beta form.
cplxblur (cplxblur)
Set fluctuations reduction in QP (before curve compression).
partitions (partitions)
Set partitions to consider as a comma-separated list of. Possible values in the list:
p8x8
8x8 P-frame partition.
p4x4
4x4 P-frame partition.
b8x8
4x4 B-frame partition.
i8x8
8x8 I-frame partition.
i4x4
4x4 I-frame partition. (Enabling p4x4 requires p8x8 to be enabled. Enabling i8x8
requires adaptive spatial transform (8x8dct option) to be enabled.)
none (none)
Do not consider any partitions.
all (all)
Consider every partition.
direct-pred (direct)
Set direct MV prediction mode. Possible values:
none (none)
Disable MV prediction.
spatial (spatial)
Enable spatial predicting.
temporal (temporal)
Enable temporal predicting.
auto (auto)
Automatically decided.
slice-max-size (slice-max-size)
Set the limit of the size of each slice in bytes. If not specified but RTP payload
size (ps) is specified, that is used.
stats (stats)
Set the file name for multi-pass stats.
nal-hrd (nal-hrd)
Set signal HRD information (requires vbv-bufsize to be set). Possible values:
none (none)
Disable HRD information signaling.
vbr (vbr)
Variable bit rate.
cbr (cbr)
Constant bit rate (not allowed in MP4 container).
x264opts (N.A.)
Set any x264 option, see x264 --fullhelp for a list.
Argument is a list of key=value couples separated by ":". In filter and psy-rd options
that use ":" as a separator themselves, use "," instead. They accept it as well since
long ago but this is kept undocumented for some reason.
For example to specify libx264 encoding options with ffmpeg:
ffmpeg -i foo.mpg -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 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.
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.
Use ffmpeg-codecs online using onworks.net services
