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 ( GOP ) size. Default value is 12.

ar integer (decoding/encoding,audio)

Set audio sampling rate (in Hz).

ac integer (decoding/encoding,audio)

Set number of audio channels.

cutoff integer (encoding,audio)

Set cutoff bandwidth. (Supported only by selected encoders, see their respective documentation sections.)

frame_size integer (encoding,audio)

Set audio frame size.

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

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 an older more strict version of the spec or reference software

strict

strictly conform to all the things in the spec no matter what consequences

normal
unofficial

allow unofficial extensions

experimental

allow non standardized experimental things, experimental (unfinished/work in progress/not well tested) decoders and encoders. Note: experimental decoders can pose a security risk, do not use this for decoding untrusted input.

b_qoffset float (encoding,video)

Set QP offset between P and B frames.

err_detect flags (decoding,audio,video)

Set error detection flags.

Possible values:
crccheck

verify embedded CRCs

bitstream

detect bitstream specification deviations

buffer

detect improper bitstream length

explode

abort decoding on minor error detection

ignore_err

ignore decoding errors, and continue decoding. This is useful if you want to analyze the content of a video and thus want everything to be decoded no matter what. This option will not result in a video that is pleasing to watch in case of errors.

careful

consider things that violate the spec and have not been seen in the wild as errors

compliant

consider all spec non compliancies as errors

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.

sar rational number (encoding,video)

Set sample aspect ratio. Alias to aspect.

debug flags (decoding/encoding,audio,video,subtitles)

Print specific debug info.

Possible values:
pict

picture info

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

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

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

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

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

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

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)

Set the number of threads to be used, in case the selected codec implementation supports multi-threading.

Possible values:
auto, 0

automatically select the number of threads to set

Default value is auto.

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

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)

Possible values:
bt709

BT.709

bt470m

BT.470 M

bt470bg

BT.470 BG

smpte170m

SMPTE 170 M

smpte240m

SMPTE 240 M

film

Film

bt2020

BT.2020

smpte428
smpte428_1

SMPTE ST 428−1

smpte431

SMPTE 431−2

smpte432

SMPTE 432−1

jedec−p22

JEDEC P22

color_trc integer (decoding/encoding,video)

Possible values:
bt709

BT.709

gamma22

BT.470 M

gamma28

BT.470 BG

smpte170m

SMPTE 170 M

smpte240m

SMPTE 240 M

linear

Linear

log

log100

Log

log_sqrt
log316

Log square root

iec61966_2_4
iec61966−2−4

IEC 61966−2−4

bt1361
bt1361e

BT.1361

iec61966_2_1
iec61966−2−1

IEC 61966−2−1

bt2020_10
bt2020_10bit

BT.2020 − 10 bit

bt2020_12
bt2020_12bit

BT.2020 − 12 bit

smpte2084

SMPTE ST 2084

smpte428
smpte428_1

SMPTE ST 428−1

arib−std−b67

ARIB STD−B67

colorspace integer (decoding/encoding,video)

Possible values:

rgb

RGB

bt709

BT.709

fcc

FCC

bt470bg

BT.470 BG

smpte170m

SMPTE 170 M

smpte240m

SMPTE 240 M

ycocg

YCOCG

bt2020nc
bt2020_ncl

BT.2020 NCL

bt2020c
bt2020_cl

BT.2020 CL

smpte2085

SMPTE 2085

color_range integer (decoding/encoding,video)

If used as input parameter, it serves as a hint to the decoder, which color_range the input has. Possible values:

mpeg

MPEG (219*2^(n−8))

jpeg

JPEG (2^n−1)

chroma_sample_location integer (decoding/encoding,video)

Possible values:
left
center
topleft

top

bottomleft
bottom

log_level_offset integer

Set the log level offset.

slices integer (encoding,video)

Number of slices, used in parallelized encoding.

thread_type flags (decoding/encoding,video)

Select which multithreading methods to use.

Use of frame will increase decoding delay by one frame per thread, so clients which cannot provide future frames should not use it.

Possible values:
slice

Decode more than one part of a single frame at once.

Multithreading using slices works only when the video was encoded with slices.

frame

Decode more than one frame at once.

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

max_pixels integer (decoding/encoding,video)

Maximum number of pixels per image. This value can be used to avoid out of memory failures due to large images.

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 milliseconds. 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 background.

txt_opacity

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

ENCODERS

Encoders are configured elements in FFmpeg which allow the encoding of multimedia streams.

When you configure your FFmpeg build, all the supported native encoders are enabled by default. Encoders requiring an external library must be enabled manually via the corresponding "−−enable−lib" option. You can list all available encoders using the configure option "−−list−encoders".

You can disable all the encoders with the configure option "−−disable−encoders" and selectively enable / disable single encoders with the options "−−enable−encoder=ENCODER" / "−−disable−encoder=ENCODER".

The option "−encoders" of the ff* tools will display the list of enabled encoders.

AUDIO ENCODERS

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

aac
Advanced Audio Coding ( AAC ) encoder.

This encoder is the default AAC encoder, natively implemented into FFmpeg. Its quality is on par or better than libfdk_aac at the default bitrate of 128kbps. This encoder also implements more options, profiles and samplerates than other encoders (with only the AAC-HE profile pending to be implemented) so this encoder has become the default and is the recommended choice.

Options

	b		Set bit rate in bits/s. Setting this automatically activates constant bit rate ( CBR ) mode. If this option is unspecified it is set to 128kbps.
	q		Set quality for variable bit rate ( VBR ) mode. This option is valid only using the ffmpeg command-line tool. For library interface users, use global_quality.

cutoff

Set cutoff frequency. If unspecified will allow the encoder to dynamically adjust the cutoff to improve clarity on low bitrates.

aac_coder

Set AAC encoder coding method. Possible values:
twoloop

Two loop searching ( TLS ) method.

This method first sets quantizers depending on band thresholds and then tries to find an optimal combination by adding or subtracting a specific value from all quantizers and adjusting some individual quantizer a little. Will tune itself based on whether aac_is, aac_ms and aac_pns are enabled. This is the default choice for a coder.

anmr

Average noise to mask ratio ( ANMR ) trellis-based solution.

This is an experimental coder which currently produces a lower quality, is more unstable and is slower than the default twoloop coder but has potential. Currently has no support for the aac_is or aac_pns options. Not currently recommended.

fast

Constant quantizer method.

This method sets a constant quantizer for all bands. This is the fastest of all the methods and has no rate control or support for aac_is or aac_pns. Not recommended.

aac_ms

Sets mid/side coding mode. The default value of "auto" will automatically use M/S with bands which will benefit from such coding. Can be forced for all bands using the value "enable", which is mainly useful for debugging or disabled using "disable".

aac_is

Sets intensity stereo coding tool usage. By default, it’s enabled and will automatically toggle IS for similar pairs of stereo bands if it’s benefitial. Can be disabled for debugging by setting the value to "disable".

aac_pns

Uses perceptual noise substitution to replace low entropy high frequency bands with imperceivable white noise during the decoding process. By default, it’s enabled, but can be disabled for debugging purposes by using "disable".

aac_tns

Enables the use of a multitap FIR filter which spans through the high frequency bands to hide quantization noise during the encoding process and is reverted by the decoder. As well as decreasing unpleasant artifacts in the high range this also reduces the entropy in the high bands and allows for more bits to be used by the mid-low bands. By default it’s enabled but can be disabled for debugging by setting the option to "disable".

aac_ltp

Enables the use of the long term prediction extension which increases coding efficiency in very low bandwidth situations such as encoding of voice or solo piano music by extending constant harmonic peaks in bands throughout frames. This option is implied by profile:a aac_low and is incompatible with aac_pred. Use in conjunction with −ar to decrease the samplerate.

aac_pred

Enables the use of a more traditional style of prediction where the spectral coefficients transmitted are replaced by the difference of the current coefficients minus the previous "predicted" coefficients. In theory and sometimes in practice this can improve quality for low to mid bitrate audio. This option implies the aac_main profile and is incompatible with aac_ltp.

profile

Sets the encoding profile, possible values:
aac_low

The default, AAC "Low-complexity" profile. Is the most compatible and produces decent quality.

mpeg2_aac_low

Equivalent to "−profile:a aac_low −aac_pns 0". PNS was introduced with the MPEG4 specifications.

aac_ltp

Long term prediction profile, is enabled by and will enable the aac_ltp option. Introduced in MPEG4.

aac_main

Main-type prediction profile, is enabled by and will enable the aac_pred option. Introduced in MPEG2.

If this option is unspecified it is set to aac_low.

ac3 and ac3_fixed
AC−3 audio encoders.

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

The ac3 encoder uses floating-point math, while the ac3_fixed encoder only uses fixed-point integer math. This does not mean that one is always faster, just that one or the other may be better suited to a particular system. The 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.

notindicated

Not Indicated (default)

large

Large Room

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.

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.

notindicated

Not Indicated (default)

ltrt

Lt/Rt Downmix Preferred

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.

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.

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.

standard

Standard A/D Converter (default)

hdcd

HDCD A/D Converter

Other AC−3 Encoding Options
−stereo_rematrixing boolean

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

cutoff frequency

Set lowpass cutoff frequency. If unspecified, the encoder selects a default determined by various other encoding parameters.

Floating-Point-Only AC−3 Encoding Options

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

Enables/Disables use of channel coupling, which is an optional AC−3 feature that increases quality by combining high frequency information from multiple channels into a single channel. The per-channel high frequency information is sent with less accuracy in both the frequency and time domains. This allows more bits to be used for lower frequencies while preserving enough information to reconstruct the high frequencies. This option is enabled by default for the floating-point encoder and should generally be left as enabled except for testing purposes or to increase encoding speed.

−1

auto

Selected by Encoder (default)

	0
	off		Disable Channel Coupling
	1
	on		Enable Channel Coupling

−cpl_start_band number

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

−1

auto

Selected by Encoder (default)

flac
FLAC (Free Lossless Audio Codec) Encoder

Options

The following options are supported by FFmpeg’s flac encoder.
compression_level

Sets the compression level, which chooses defaults for many other options if they are not set explicitly. Valid values are from 0 to 12, 5 is the default.

frame_size

Sets the size of the frames in samples per channel.

lpc_coeff_precision

Sets the LPC coefficient precision, valid values are from 1 to 15, 15 is the default.

lpc_type

Sets the first stage LPC algorithm
none

LPC is not used

fixed

fixed LPC coefficients

levinson
cholesky

lpc_passes

Number of passes to use for Cholesky factorization during LPC analysis

min_partition_order

The minimum partition order

max_partition_order

The maximum partition order

prediction_order_method

estimation
2level
4level
8level
search

Bruteforce search

log

ch_mode

Channel mode
auto

The mode is chosen automatically for each frame

indep

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.

opus
Opus encoder.

This is a native FFmpeg encoder for the Opus format. Currently its in development and only implements the CELT part of the codec. Its quality is usually worse and at best is equal to the libopus encoder.

Options

Set bit rate in bits/s. If unspecified it uses the number of channels and the layout to make a good guess.

opus_delay

Sets the maximum delay in milliseconds. Lower delays than 20ms will very quickly decrease quality.

libfdk_aac
libfdk-aac AAC (Advanced Audio Coding) encoder wrapper.

The libfdk-aac library is based on the Fraunhofer FDK AAC code from the Android project.

Requires the presence of the libfdk-aac headers and library during configuration. You need to explicitly configure the build with "−−enable−libfdk−aac". The library is also incompatible with GPL, so if you allow the use of GPL, you should configure with "−−enable−gpl −−enable−nonfree −−enable−libfdk−aac".

This encoder is considered to produce output on par or worse at 128kbps to the the native FFmpeg AAC encoder but can often produce better sounding audio at identical or lower bitrates and has support for the AAC-HE profiles.

VBR encoding, enabled through the vbr or flags +qscale options, is experimental and only works with some combinations of parameters.

Support for encoding 7.1 audio is only available with libfdk-aac 0.1.3 or higher.

For more information see the fdk-aac project at <http://sourceforge.net/p/opencore−amr/fdk−aac/>.

Options

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

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.

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.

cutoff (−−lowpass)

Set lowpass cutoff frequency. If unspecified, the encoder dynamically adjusts the cutoff.

reservoir

Enable use of bit reservoir when set to 1. Default value is 1. LAME has this enabled by default, but can be overridden by use −−nores option.

joint_stereo (−m j)

Enable the encoder to use (on a frame by frame basis) either L/R stereo or mid/side stereo. Default value is 1.

abr (−−abr)

Enable the encoder to use ABR when set to 1. The lame −−abr sets the target bitrate, while this options only tells FFmpeg to use ABR still relies on b to set bitrate.

libopencore-amrnb
OpenCORE Adaptive Multi-Rate Narrowband encoder.

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

This is a mono-only encoder. Officially it only supports 8000Hz sample rate, but you can override it by setting strict to unofficial or lower.

Options

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

4750
5150
5900
6700
7400
7950
10200
12200

dtx

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

libopus
libopus Opus Interactive Audio Codec encoder wrapper.

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

Option Mapping

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

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

vbr (vbr, hard-cbr, and cvbr)

Set VBR mode. The FFmpeg vbr option has the following valid arguments, with the opusenc equivalent options in parentheses:
off (hard-cbr)

Use constant bit rate encoding.

on (vbr)

Use variable bit rate encoding (the default).

constrained (cvbr)

Use constrained variable bit rate encoding.

compression_level (comp)

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

frame_duration (framesize)

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

packet_loss (expect-loss)

Set expected packet loss percentage. The default is 0.

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).

mapping_family (mapping_family)

Set channel mapping family to be used by the encoder. The default value of −1 uses mapping family 0 for mono and stereo inputs, and mapping family 1 otherwise. The default also disables the surround masking and LFE bandwidth optimzations in libopus, and requires that the input contains 8 channels or fewer.

Other values include 0 for mono and stereo, 1 for surround sound with masking and LFE bandwidth optimizations, and 255 for independent streams with an unspecified channel layout.

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".

VIDEO ENCODERS

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

Hap
Vidvox Hap video encoder.

Options
format integer

Specifies the Hap format to encode.

hap

hap_alpha
hap_q

Default value is hap.

chunks integer

Specifies the number of chunks to split frames into, between 1 and 64. This permits multithreaded decoding of large frames, potentially at the cost of data-rate. The encoder may modify this value to divide frames evenly.

Default value is 1.

compressor integer

Specifies the second-stage compressor to use. If set to none, chunks will be limited to 1, as chunked uncompressed frames offer no benefit.
none
snappy

Default value is snappy.

jpeg2000
The native jpeg 2000 encoder is lossy by default, the "−q:v" option can be used to set the encoding quality. Lossless encoding can be selected with "−pred 1".

Options
format

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

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

Set target video bitrate in bit/s and enable rate control.

kvazaar-params

Set kvazaar parameters as a list of name=value pairs separated by commas (,). See kvazaar documentation for a list of options.

libopenh264
Cisco libopenh264 H.264/MPEG−4 AVC encoder wrapper.

This encoder requires the presence of the libopenh264 headers and library during configuration. You need to explicitly configure the build with "−−enable−libopenh264". The library is detected using pkg-config.

For more information about the library see <http://www.openh264.org>.

Options

The following FFmpeg global options affect the configurations of the libopenh264 encoder.

	b		Set the bitrate (as a number of bits per second).
	g		Set the GOP size.

maxrate

Set the max bitrate (as a number of bits per second).

flags +global_header

Set global header in the bitstream.

slices

Set the number of slices, used in parallelized encoding. Default value is 0. This is only used when slice_mode is set to fixed.

slice_mode

Set slice mode. Can assume one of the following possible values:
fixed

a fixed number of slices

rowmb

one slice per row of macroblocks

auto

automatic number of slices according to number of threads

dyn

dynamic slicing

Default value is auto.

loopfilter

Enable loop filter, if set to 1 (automatically enabled). To disable set a value of 0.

profile

Set profile restrictions. If set to the value of main enable CABAC (set the "SEncParamExt.iEntropyCodingModeFlag" flag to 1).

max_nal_size

Set maximum NAL size in bytes.

allow_skip_frames

Allow skipping frames to hit the target bitrate if set to 1.

libtheora
libtheora Theora encoder wrapper.

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

For more information about the libtheora project see <http://www.theora.org/>.

Options

The following global options are mapped to internal libtheora options which affect the quality and the bitrate of the encoded stream.

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.

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.

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)
tune (tune)

psnr (psnr)
ssim (ssim)

quality, deadline (deadline)

best

Use best quality deadline. Poorly named and quite slow, this option should be avoided as it may give worse quality output than good.

good

Use good quality deadline. This is a good trade-off between speed and quality when used with the cpu-used option.

realtime

Use realtime quality deadline.

speed, cpu-used (cpu-used)

Set quality/speed ratio modifier. Higher values speed up the encode at the cost of quality.

nr (noise-sensitivity)
static-thresh

Set a change threshold on blocks below which they will be skipped by the encoder.

slices (token-parts)

Note that FFmpeg’s slices option gives the total number of partitions, while vpxenc’s token-parts is given as "log2(partitions)".

max-intra-rate

Set maximum I−frame bitrate as a percentage of the target bitrate. A value of 0 means unlimited.

force_key_frames

"VPX_EFLAG_FORCE_KF"

Alternate reference frame related

auto-alt-ref

Enable use of alternate reference frames (2−pass only).

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 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).

forced-idr

Normally, when forcing a I−frame type, the encoder can select any type of I−frame. This option forces it to choose an IDR-frame.

subq (subme)

Sub-pixel motion estimation method.

b_strategy (b−adapt)

Adaptive B−frame placement decision algorithm. Use only on first-pass.

keyint_min (min-keyint)

Minimum GOP size.

coder

Set entropy encoder. Possible values:

	ac		Enable CABAC.
	vlc		Enable CAVLC and disable CABAC. It generates the same effect as x264’s −−no−cabac option.
	cmp

Set full pixel motion estimation comparison algorithm. Possible values:
chroma

Enable chroma in motion estimation.

sad

Ignore chroma in motion estimation. It generates the same effect as x264’s −−no−chroma−me option.

threads (threads)

Number of encoding threads.

thread_type

Set multithreading technique. Possible values:
slice

Slice-based multithreading. It generates the same effect as x264’s −−sliced−threads option.

frame

Frame-based multithreading.

flags

Set encoding flags. It can be used to disable closed GOP and enable open GOP by setting it to "−cgop". The result is similar to the behavior of x264’s −−open−gop option.

rc_init_occupancy (vbv-init)
preset (preset)

Set the encoding preset.

tune (tune)

Set tuning of the encoding params.

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

a53cc boolean

Import closed captions (which must be ATSC compatible format) into output. Only the mpeg2 and h264 decoders provide these. Default is 1 (on).

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.

forced-idr

Normally, when forcing a I−frame type, the encoder can select any type of I−frame. This option forces it to choose an IDR-frame.

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

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.

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.

never

Never write it.

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

standard

4444

quant_mat integer

Select quantization matrix.
auto
default
proxy

standard

If set to auto, the matrix matching the profile will be picked. If not set, the matrix providing the highest quality, default, will be picked.

bits_per_mb integer

How many bits to allot for coding one macroblock. Different profiles use between 200 and 2400 bits per macroblock, the maximum is 8000.

mbs_per_slice integer

Number of macroblocks in each slice (1−8); the default value (8) should be good in almost all situations.

vendor string

Override the 4−byte vendor ID. A custom vendor ID like apl0 would claim the stream was produced by the Apple encoder.

alpha_bits integer

Specify number of bits for alpha component. Possible values are 0, 8 and 16. Use 0 to disable alpha plane coding.

Speed considerations

In the default mode of operation the encoder has to honor frame constraints (i.e. not produce frames with size bigger than requested) while still making output picture as good as possible. A frame containing a lot of small details is harder to compress and the encoder would spend more time searching for appropriate quantizers for each slice.

Setting a higher bits_per_mb limit will improve the speed.

For the fastest encoding speed set the qscale parameter (4 is the recommended value) and do not set a size constraint.

QSV encoders
The family of Intel QuickSync Video encoders ( MPEG−2, H.264 and HEVC )

The ratecontrol method is selected as follows:

•

When global_quality is specified, a quality-based mode is used. Specifically this means either

−

			CQP − constant quantizer scale, when the qscale codec flag is also set (the −qscale ffmpeg option).
	−		LA_ICQ − intelligent constant quality with lookahead, when the look_ahead option is also set.
	−		ICQ -- intelligent constant quality otherwise.
	•

Otherwise, a bitrate-based mode is used. For all of those, you should specify at least the desired average bitrate with the b option.

	−		LA − VBR with lookahead, when the look_ahead option is specified.
	−		VCM − video conferencing mode, when the vcm option is set.
	−		CBR − constant bitrate, when maxrate is specified and equal to the average bitrate.
	−		VBR − variable bitrate, when maxrate is specified, but is higher than the average bitrate.
	−		AVBR − average VBR mode, when maxrate is not specified. This mode is further configured by the avbr_accuracy and avbr_convergence options.

Note that depending on your system, a different mode than the one you specified may be selected by the encoder. Set the verbosity level to verbose or higher to see the actual settings used by the QSV runtime.

Additional libavcodec global options are mapped to MSDK options as follows:

	•		g/gop_size −> GopPicSize
	•		bf/max_b_frames+1 −> GopRefDist
	•		rc_init_occupancy/rc_initial_buffer_occupancy −> InitialDelayInKB
	•		slices −> NumSlice
	•		refs −> NumRefFrame
	•		b_strategy/b_frame_strategy −> BRefType
	•		cgop/CLOSED_GOP codec flag −> GopOptFlag
	•		For the CQP mode, the i_qfactor/i_qoffset and b_qfactor/b_qoffset set the difference between QPP and QPI , and QPP and QPB respectively.
	•		Setting the coder option to the value vlc will make the H.264 encoder use CAVLC instead of CABAC.

snow
Options
iterative_dia_size

dia size for the iterative motion estimation

vc2
SMPTE VC−2 (previously BBC Dirac Pro). This codec was primarily aimed at professional broadcasting but since it supports yuv420, yuv422 and yuv444 at 8 (limited range or full range), 10 or 12 bits, this makes it suitable for other tasks which require low overhead and low compression (like screen recording).

Options

Sets target video bitrate. Usually that’s around 1:6 of the uncompressed video bitrate (e.g. for 1920x1080 50fps yuv422p10 that’s around 400Mbps). Higher values (close to the uncompressed bitrate) turn on lossless compression mode.

field_order

Enables field coding when set (e.g. to tt − top field first) for interlaced inputs. Should increase compression with interlaced content as it splits the fields and encodes each separately.

wavelet_depth

Sets the total amount of wavelet transforms to apply, between 1 and 5 (default). Lower values reduce compression and quality. Less capable decoders may not be able to handle values of wavelet_depth over 3.

wavelet_type

Sets the transform type. Currently only 5_3 (LeGall) and 9_7 (Deslauriers-Dubuc) are implemented, with 9_7 being the one with better compression and thus is the default.

slice_width
slice_height

Sets the slice size for each slice. Larger values result in better compression. For compatibility with other more limited decoders use slice_width of 32 and slice_height of 8.

tolerance

Sets the undershoot tolerance of the rate control system in percent. This is to prevent an expensive search from being run.

Sets the quantization matrix preset to use by default or when wavelet_depth is set to 5

−

			default Uses the default quantization matrix from the specifications, extended with values for the fifth level. This provides a good balance between keeping detail and omitting artifacts.
	−		flat Use a completely zeroed out quantization matrix. This increases PSNR but might reduce perception. Use in bogus benchmarks.
	−		color Reduces detail but attempts to preserve color at extremely low bitrates.

SUBTITLES ENCODERS

dvdsub
This codec encodes the bitmap subtitle format that is used in DVDs. Typically they are stored in VOBSUB file pairs (*.idx + *.sub), and they can also be used in Matroska files.

Options
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 <http://source.ffmpeg.org>.

Maintainers for the specific components are listed in the file MAINTAINERS in the source code tree.

pdf

FFMPEG-CODECS

NAME

DESCRIPTION

CODEC OPTIONS

DECODERS

VIDEO DECODERS

AUDIO DECODERS

SUBTITLES DECODERS

ENCODERS

AUDIO ENCODERS

VIDEO ENCODERS

SUBTITLES ENCODERS

SEE ALSO

AUTHORS