GNU/Linux man pages
Livre :
Expressions régulières,
Syntaxe et mise en oeuvre :
GNU/Linux |
Debian 7.3.0(Wheezy) |
|
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ffprobe(1) |
 |
ffprobe − ffprobe media prober
The generic syntax is:
ffprobe [options] [F<input_file>]
ffprobe gathers information from multimedia streams and prints it in human− and machine-readable fashion.
For example it can be used to check the format of the container used by a multimedia stream and the format and type of each media stream contained in it.
If a filename is specified in input, ffprobe will try to open and probe the file content. If the file cannot be opened or recognized as a multimedia file, a positive exit code is returned.
ffprobe may be employed both as a standalone application or in combination with a textual filter, which may perform more sophisticated processing, e.g. statistical processing or plotting.
Options are used to list some of the formats supported by ffprobe or for specifying which information to display, and for setting how ffprobe will show it.
ffprobe output is designed to be easily parsable by a textual filter, and consists of one or more sections of a form defined by the selected writer, which is specified by the print_format option.
Metadata tags stored in the container or in the streams are recognized and printed in the corresponding " FORMAT " or " STREAM " section.
All the numerical options, if not specified otherwise, accept in input a string representing a number, which may contain one of the International System number postfixes, for example ’K’, ’M’, ’G’. If ’i’ is appended after the postfix, powers of 2 are used instead of powers of 10. The ’B’ postfix multiplies the value for 8, and can be appended after another postfix or used alone. This allows using for example ’ KB ’, ’MiB’, ’G’ and ’B’ as postfix.
Options which do not take arguments are boolean options, and set the corresponding value to true. They can be set to false by prefixing with "no" the option name, for example using "−nofoo" in the command line will set to false the boolean option with name "foo".
Stream
specifiers
Some options are applied per-stream, e.g. bitrate or codec.
Stream specifiers are used to precisely specify which
stream(s) does a given option belong to.
A stream specifier is a string generally appended to the option name and separated from it by a colon. E.g. "−codec:a:1 ac3" option contains "a:1" stream specifier, which matches the second audio stream. Therefore it would select the ac3 codec for the second audio stream.
A stream specifier can match several streams, the option is then applied to all of them. E.g. the stream specifier in "−b:a 128k" matches all audio streams.
An empty stream specifier matches all streams, for example "−codec copy" or "−codec: copy" would copy all the streams without reencoding.
Possible forms
of stream specifiers are:
stream_index
Matches the stream with this index. E.g. "−threads:1 4" would set the thread count for the second stream to 4.
stream_type[:stream_index]
stream_type is one of: ’v’ for video, ’a’ for audio, ’s’ for subtitle, ’d’ for data and ’t’ for attachments. If stream_index is given, then matches stream number stream_index of this type. Otherwise matches all streams of this type.
p:program_id[:stream_index]
If stream_index is given, then matches stream number stream_index in program with id program_id. Otherwise matches all streams in this program.
#stream_id
Matches the stream by format-specific ID .
Generic
options
These options are shared amongst the av* tools.
|
−L |
Show license. |
−h, −?, −help, −−help [arg]
Show help. An optional parameter may be specified to print help about a specific item.
Possible values
of arg are:
decoder=decoder_name
Print detailed information about the decoder named decoder_name. Use the −decoders option to get a list of all decoders.
encoder=encoder_name
Print detailed information about the encoder named encoder_name. Use the −encoders option to get a list of all encoders.
demuxer=demuxer_name
Print detailed information about the demuxer named demuxer_name. Use the −formats option to get a list of all demuxers and muxers.
muxer=muxer_name
Print detailed information about the muxer named muxer_name. Use the −formats option to get a list of all muxers and demuxers.
−version
Show version.
−formats
Show available formats.
The fields preceding the format names have the following meanings:
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D |
Decoding available |
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E |
Encoding available |
−codecs
Show all codecs known to libavcodec.
Note that the term ’codec’ is used throughout this documentation as a shortcut for what is more correctly called a media bitstream format.
−decoders
Show available decoders.
−encoders
Show all available encoders.
−bsfs
Show available bitstream filters.
−protocols
Show available protocols.
−filters
Show available libavfilter filters.
−pix_fmts
Show available pixel formats.
−sample_fmts
Show available sample formats.
−layouts
Show channel names and standard channel layouts.
−loglevel loglevel | −v loglevel
Set the logging level used by
the library. loglevel is a number or a string
containing one of the following values:
quiet
panic
fatal
error
warning
info
verbose
debug
By default the program logs to stderr, if coloring is supported by the terminal, colors are used to mark errors and warnings. Log coloring can be disabled setting the environment variable AV_LOG_FORCE_NOCOLOR or NO_COLOR , or can be forced setting the environment variable AV_LOG_FORCE_COLOR . The use of the environment variable NO_COLOR is deprecated and will be dropped in a following FFmpeg version.
−report
Dump full command line and console output to a file named "program−YYYYMMDD−HHMMSS.log" in the current directory. This file can be useful for bug reports. It also implies "−loglevel verbose".
Note: setting the environment variable "FFREPORT" to any value has the same effect.
−cpuflags flags (global)
Allows setting and clearing cpu flags. This option is intended for testing. Do not use it unless you know what you’re doing.
ffmpeg −cpuflags −sse+mmx ...
ffmpeg −cpuflags mmx ...
ffmpeg −cpuflags 0 ...
AVOptions
These options are provided directly by the libavformat,
libavdevice and libavcodec libraries. To see the list of
available AVOptions, use the −help option. They
are separated into two categories:
generic
These options can be set for any container, codec or device. Generic options are listed under AVFormatContext options for containers/devices and under AVCodecContext options for codecs.
private
These options are specific to the given container, device or codec. Private options are listed under their corresponding containers/devices/codecs.
For example to write an ID3v2.3 header instead of a default ID3v2.4 to an MP3 file, use the id3v2_version private option of the MP3 muxer:
ffmpeg −i input.flac −id3v2_version 3 out.mp3
All codec AVOptions are obviously per-stream, so the chapter on stream specifiers applies to them
Note −nooption syntax cannot be used for boolean AVOptions, use −option 0/−option 1.
Note2 old undocumented way of specifying per-stream AVOptions by prepending v/a/s to the options name is now obsolete and will be removed soon.
Codec
AVOptions
−b[:stream_specifier] integer
(output,audio,video)
set bitrate (in bits/s)
−ab[:stream_specifier] integer (output,audio)
set bitrate (in bits/s)
−bt[:stream_specifier] integer (output,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[:stream_specifier] flags (input/output,audio,video,subtitles)
Possible values:
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mv4 |
use four motion vector by macroblock (mpeg4) |
qpel
use 1/4 pel motion compensation
loop
use loop filter
qscale
use fixed qscale
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gmc |
use gmc |
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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
don’t draw edges
psnr
error[?] variables will be set 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
use only bitexact stuff (except (i)dct)
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aic |
h263 advanced intra coding / mpeg4 ac prediction |
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cbp |
Deprecated, use mpegvideo private options instead |
qprd
Deprecated, use mpegvideo private options instead
ilme
interlaced motion estimation
cgop
closed gop
−sub_id[:stream_specifier]
integer ()
−me_method[:stream_specifier] integer
(output,video)
set motion estimation method
Possible
values:
zero
zero motion estimation (fastest)
full
full motion estimation (slowest)
epzs
EPZS motion estimation (default)
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esa |
esa motion estimation (alias for full) |
tesa
tesa motion estimation
|
dia |
dia motion estimation (alias for epzs) |
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log |
log motion estimation |
phods
phods motion estimation
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x1 |
X1 motion estimation |
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hex |
hex motion estimation |
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umh |
umh motion estimation |
iter
iter motion estimation
−extradata_size[:stream_specifier]
integer ()
−time_base[:stream_specifier] rational
number ()
−g[:stream_specifier] integer
(output,video)
set the group of picture size
−ar[:stream_specifier] integer (input/output,audio)
set audio sampling rate (in Hz)
−ac[:stream_specifier] integer (input/output,audio)
set number of audio channels
−cutoff[:stream_specifier] integer (output,audio)
set cutoff bandwidth
−frame_size[:stream_specifier]
integer (output,audio)
−frame_number[:stream_specifier] integer
()
−delay[:stream_specifier] integer ()
−qcomp[:stream_specifier] float
(output,video)
video quantizer scale compression ( VBR ). Constant of ratecontrol equation. Recommended range for default rc_eq: 0.0−1.0
−qblur[:stream_specifier] float (output,video)
video quantizer scale blur ( VBR )
−qmin[:stream_specifier] integer (output,video)
min video quantizer scale ( VBR )
−qmax[:stream_specifier] integer (output,video)
max video quantizer scale ( VBR )
−qdiff[:stream_specifier] integer (output,video)
max difference between the quantizer scale ( VBR )
−bf[:stream_specifier] integer (output,video)
use ’frames’ B frames
−b_qfactor[:stream_specifier] float (output,video)
qp factor between p and b frames
−rc_strategy[:stream_specifier] integer (output,video)
ratecontrol method
−b_strategy[:stream_specifier] integer (output,video)
strategy to choose between I/P/B−frames
−ps[:stream_specifier] integer (output,video)
rtp payload size in bytes
−mv_bits[:stream_specifier]
integer ()
−header_bits[:stream_specifier] integer
()
−i_tex_bits[:stream_specifier] integer
()
−p_tex_bits[:stream_specifier] integer
()
−i_count[:stream_specifier] integer ()
−p_count[:stream_specifier] integer ()
−skip_count[:stream_specifier] integer
()
−misc_bits[:stream_specifier] integer ()
−frame_bits[:stream_specifier] integer
()
−codec_tag[:stream_specifier] integer ()
−bug[:stream_specifier] flags
(input,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)
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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
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ms |
workaround various bugs in microsofts broken decoders |
trunc
trancated frames
−lelim[:stream_specifier] integer (output,video)
single coefficient elimination threshold for luminance (negative values also consider dc coefficient)
−celim[:stream_specifier] integer (output,video)
single coefficient elimination threshold for chrominance (negative values also consider dc coefficient)
−strict[:stream_specifier] integer (input/output,audio,video)
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
−b_qoffset[:stream_specifier] float (output,video)
qp offset between P and B frames
−err_detect[:stream_specifier] flags (input,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
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[:stream_specifier]
integer ()
−block_align[:stream_specifier] integer
()
−mpeg_quant[:stream_specifier] integer
(output,video)
use MPEG quantizers instead of H.263
−stats_out[:stream_specifier]
string ()
−qsquish[:stream_specifier] float
(output,video)
how to keep quantizer between qmin and qmax (0 = clip, 1 = use differentiable function)
−rc_qmod_amp[:stream_specifier] float (output,video)
experimental quantizer modulation
−rc_qmod_freq[:stream_specifier] integer (output,video)
experimental quantizer modulation
−rc_override_count[:stream_specifier]
integer ()
−rc_eq[:stream_specifier] string
(output,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[:stream_specifier] integer (output,audio,video)
Set max bitrate tolerance (in bits/s). Requires bufsize to be set.
−minrate[:stream_specifier] integer (output,audio,video)
Set min bitrate tolerance (in bits/s). Most useful in setting up a CBR encode. It is of little use elsewise.
−bufsize[:stream_specifier] integer (output,audio,video)
set ratecontrol buffer size (in bits)
−rc_buf_aggressivity[:stream_specifier] float (output,video)
currently useless
−i_qfactor[:stream_specifier] float (output,video)
qp factor between P and I frames
−i_qoffset[:stream_specifier] float (output,video)
qp offset between P and I frames
−rc_init_cplx[:stream_specifier] float (output,video)
initial complexity for 1−pass encoding
−dct[:stream_specifier] integer (output,video)
DCT algorithm
Possible
values:
auto
autoselect a good one (default)
fastint
fast integer
|
int |
accurate integer |
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|
mmx |
altivec
faan
floating point AAN DCT
−lumi_mask[:stream_specifier] float (output,video)
compresses bright areas stronger than medium ones
−tcplx_mask[:stream_specifier] float (output,video)
temporal complexity masking
−scplx_mask[:stream_specifier] float (output,video)
spatial complexity masking
−p_mask[:stream_specifier] float (output,video)
inter masking
−dark_mask[:stream_specifier] float (output,video)
compresses dark areas stronger than medium ones
−idct[:stream_specifier] integer (input/output,video)
select IDCT implementation
Possible
values:
auto
|
int |
simple
simplemmx
libmpeg2mmx
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mmi |
||
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arm |
altivec
|
sh4 |
simplearm
simplearmv5te
simplearmv6
simpleneon
simplealpha
h264
|
vp3 |
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|
ipp |
xvidmmx
faani
floating point AAN IDCT
−slice_count[:stream_specifier]
integer ()
−ec[:stream_specifier] flags
(input,video)
set error concealment strategy
Possible
values:
guess_mvs
iterative motion vector ( MV ) search (slow)
deblock
use strong deblock filter for damaged MBs
−bits_per_coded_sample[:stream_specifier]
integer ()
−pred[:stream_specifier] integer
(output,video)
prediction method
Possible
values:
left
plane
median
−aspect[:stream_specifier] rational number (output,video)
sample aspect ratio
−debug[:stream_specifier] flags (input/output,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 ) |
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|
mv |
motion vector |
dct_coeff
skip
startcode
|
pts |
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|
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
−vismv[:stream_specifier] integer (input,video)
visualize motion vectors (MVs)
Possible values:
|
pf |
forward predicted MVs of P−frames |
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|
bf |
forward predicted MVs of B−frames |
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|
bb |
backward predicted MVs of B−frames |
−cmp[:stream_specifier] integer (output,video)
full pel me compare function
Possible values:
|
sad |
sum of absolute differences, fast (default) |
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|
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 |
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|
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 |
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|
w97 |
9/7 wavelet, only used in snow |
dctmax
chroma
−subcmp[:stream_specifier] integer (output,video)
sub pel me compare function
Possible values:
|
sad |
sum of absolute differences, fast (default) |
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|
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 |
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|
w97 |
9/7 wavelet, only used in snow |
dctmax
chroma
−mbcmp[:stream_specifier] integer (output,video)
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[:stream_specifier] integer (output,video)
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[:stream_specifier] integer (output,video)
diamond type & size for motion estimation
−last_pred[:stream_specifier] integer (output,video)
amount of motion predictors from the previous frame
−preme[:stream_specifier] integer (output,video)
pre motion estimation
−precmp[:stream_specifier] integer (output,video)
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[:stream_specifier] integer (output,video)
diamond type & size for motion estimation pre-pass
−subq[:stream_specifier] integer (output,video)
sub pel motion estimation quality
−dtg_active_format[:stream_specifier]
integer ()
−me_range[:stream_specifier] integer
(output,video)
limit motion vectors range (1023 for DivX player)
−ibias[:stream_specifier] integer (output,video)
intra quant bias
−pbias[:stream_specifier] integer (output,video)
inter quant bias
−color_table_id[:stream_specifier]
integer ()
−global_quality[:stream_specifier] integer
(output,audio,video)
−coder[:stream_specifier] integer
(output,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[:stream_specifier] integer (output,video)
context model
−slice_flags[:stream_specifier]
integer ()
−xvmc_acceleration[:stream_specifier]
integer ()
−mbd[:stream_specifier] integer
(output,video)
macroblock decision algorithm (high quality mode)
Possible
values:
simple
use mbcmp (default)
bits
use fewest bits
|
rd |
use best rate distortion |
−stream_codec_tag[:stream_specifier]
integer ()
−sc_threshold[:stream_specifier] integer
(output,video)
scene change threshold
−lmin[:stream_specifier] integer (output,video)
min lagrange factor ( VBR )
−lmax[:stream_specifier] integer (output,video)
max lagrange factor ( VBR )
−nr[:stream_specifier] integer (output,video)
noise reduction
−rc_init_occupancy[:stream_specifier] integer (output,video)
number of bits which should be loaded into the rc buffer before decoding starts
−inter_threshold[:stream_specifier]
integer (output,video)
−flags2[:stream_specifier] flags
(input/output,audio,video)
Possible values:
fast
allow non spec compliant speedup tricks
sgop
Deprecated, use mpegvideo private options instead
noout
skip bitstream encoding
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
−error[:stream_specifier]
integer (output,video)
−qns[:stream_specifier] integer
(output,video)
deprecated, use mpegvideo private options instead
−threads[:stream_specifier] integer (input/output,video)
Possible values:
auto
detect a good number of threads
−me_threshold[:stream_specifier] integer (output,video)
motion estimaton threshold
−mb_threshold[:stream_specifier] integer (output,video)
macroblock threshold
−dc[:stream_specifier] integer (output,video)
intra_dc_precision
−nssew[:stream_specifier] integer (output,video)
nsse weight
−skip_top[:stream_specifier] integer (input,video)
number of macroblock rows at the top which are skipped
−skip_bottom[:stream_specifier] integer (input,video)
number of macroblock rows at the bottom which are skipped
−profile[:stream_specifier] integer (output,audio,video)
Possible values:
unknown
aac_main
aac_low
aac_ssr
aac_ltp
aac_he
aac_he_v2
aac_ld
aac_eld
|
dts |
dts_es
dts_96_24
dts_hd_hra
dts_hd_ma
−level[:stream_specifier] integer (output,audio,video)
Possible values:
unknown
−lowres[:stream_specifier] integer (input,audio,video)
decode at 1= 1/2, 2=1/4, 3=1/8 resolutions
−skip_threshold[:stream_specifier] integer (output,video)
frame skip threshold
−skip_factor[:stream_specifier] integer (output,video)
frame skip factor
−skip_exp[:stream_specifier] integer (output,video)
frame skip exponent
−skipcmp[:stream_specifier] integer (output,video)
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[:stream_specifier] float (output,video)
increases the quantizer for macroblocks close to borders
−mblmin[:stream_specifier] integer (output,video)
min macroblock lagrange factor ( VBR )
−mblmax[:stream_specifier] integer (output,video)
max macroblock lagrange factor ( VBR )
−mepc[:stream_specifier] integer (output,video)
motion estimation bitrate penalty compensation (1.0 = 256)
−skip_loop_filter[:stream_specifier] integer (input,video)
Possible values:
none
default
noref
bidir
nokey
|
all |
−skip_idct[:stream_specifier] integer (input,video)
Possible values:
none
default
noref
bidir
nokey
|
all |
−skip_frame[:stream_specifier] integer (input,video)
Possible values:
none
default
noref
bidir
nokey
|
all |
−bidir_refine[:stream_specifier] integer (output,video)
refine the two motion vectors used in bidirectional macroblocks
−brd_scale[:stream_specifier] integer (output,video)
downscales frames for dynamic B−frame decision
−keyint_min[:stream_specifier] integer (output,video)
minimum interval between IDR-frames
−refs[:stream_specifier] integer (output,video)
reference frames to consider for motion compensation
−chromaoffset[:stream_specifier] integer (output,video)
chroma qp offset from luma
−trellis[:stream_specifier] integer (output,audio,video)
rate-distortion optimal quantization
−sc_factor[:stream_specifier] integer (output,video)
multiplied by qscale for each frame and added to scene_change_score
−mv0_threshold[:stream_specifier]
integer (output,video)
−b_sensitivity[:stream_specifier] integer
(output,video)
adjusts sensitivity of b_frame_strategy 1
−compression_level[:stream_specifier]
integer (output,audio,video)
−min_prediction_order[:stream_specifier]
integer (output,audio)
−max_prediction_order[:stream_specifier]
integer (output,audio)
−timecode_frame_start[:stream_specifier]
integer (output,video)
GOP timecode frame start number, in non drop frame format
−request_channels[:stream_specifier] integer (input,audio)
set desired number of audio channels
−bits_per_raw_sample[:stream_specifier]
integer ()
−channel_layout[:stream_specifier] integer
(input/output,audio)
Possible values:
−request_channel_layout[:stream_specifier] integer (input,audio)
Possible values:
−rc_max_vbv_use[:stream_specifier]
float (output,video)
−rc_min_vbv_use[:stream_specifier] float
(output,video)
−ticks_per_frame[:stream_specifier] integer
(input/output,audio,video)
−color_primaries[:stream_specifier] integer
(input/output,video)
−color_trc[:stream_specifier] integer
(input/output,video)
−colorspace[:stream_specifier] integer
(input/output,video)
−color_range[:stream_specifier] integer
(input/output,video)
−chroma_sample_location[:stream_specifier]
integer (input/output,video)
−log_level_offset[:stream_specifier]
integer ()
set the log level offset
−slices[:stream_specifier] integer (output,video)
number of slices, used in parallelized encoding
−thread_type[:stream_specifier] flags (input/output,video)
select multithreading type
Possible
values:
slice
frame
−audio_service_type[:stream_specifier] integer (output,audio)
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[:stream_specifier] integer (input,audio)
sample format audio decoders should prefer
Possible values:
|
u8 |
8−bit unsigned integer |
|||
|
s16 |
16−bit signed integer |
|||
|
s32 |
32−bit signed integer |
|||
|
flt |
32−bit float |
|||
|
dbl |
64−bit double |
|||
|
u8p |
8−bit unsigned integer planar |
s16p
16−bit signed integer planar
s32p
32−bit signed integer planar
fltp
32−bit float planar
dblp
64−bit double planar
−pkt_timebase[:stream_specifier] rational number ()
Format
AVOptions
−avioflags flags
(input/output)
Possible values:
direct
reduce buffering
−probesize integer (input)
set probing size
−packetsize integer (output)
set packet size
−fflags flags (input/output)
Possible values:
ignidx
ignore index
genpts
generate pts
nofillin
do not fill in missing values that can be exactly calculated
noparse
disable AVParsers, this needs nofillin too
igndts
ignore dts
discardcorrupt
discard corrupted frames
sortdts
try to interleave outputted packets by dts
keepside
dont merge side data
latm
enable RTP MP4A−LATM payload
nobuffer
reduce the latency introduced by optional buffering
−analyzeduration integer (input)
how many microseconds are analyzed to estimate duration
−cryptokey hexadecimal string (input)
decryption key
−indexmem integer (input)
max memory used for timestamp index (per stream)
−rtbufsize integer (input)
max memory used for buffering real-time frames
−fdebug flags (input/output)
print specific debug info
Possible values:
|
ts |
−max_delay integer (input/output)
maximum muxing or demuxing delay in microseconds
−fpsprobesize integer (input)
number of frames used to probe fps
−audio_preload integer (output)
microseconds by which audio packets should be interleaved earlier
−chunk_duration integer (output)
microseconds for each chunk
−chunk_size integer (output)
size in bytes for each chunk
−f_err_detect flags (input)
set error detection flags (deprecated; use err_detect, save via avconv)
Possible
values:
crccheck
verify embedded CRCs
bitstream
detect bitstream specification deviations
buffer
detect improper bitstream length
explode
abort decoding on minor error detection
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 shouldnt do as an error
−err_detect flags (input)
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
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 shouldnt do as an error
−use_wallclock_as_timestamps integer (input)
use wallclock as timestamps
−avoid_negative_ts integer (output)
avoid negative timestamps
Main options
−f format
Force format to use.
−unit
Show the unit of the displayed values.
−prefix
Use SI prefixes for the displayed values. Unless the "−byte_binary_prefix" option is used all the prefixes are decimal.
−byte_binary_prefix
Force the use of binary prefixes for byte values.
−sexagesimal
Use sexagesimal format HH:MM:SS .MICROSECONDS for time values.
−pretty
Prettify the format of the displayed values, it corresponds to the options "−unit −prefix −byte_binary_prefix −sexagesimal".
−of, −print_format writer_name[=writer_options]
Set the output printing format.
writer_name specifies the name of the writer, and writer_options specifies the options to be passed to the writer.
For example for printing the output in JSON format, specify:
−print_format json
For more details on the available output printing formats, see the Writers section below.
−show_data
Show payload data, as an hexadecimal and ASCII dump. Coupled with −show_packets, it will dump the packets’ data. Coupled with −show_streams, it will dump the codec extradata.
The dump is printed as the "data" field. It may contain newlines.
−show_error
Show information about the error found when trying to probe the input.
The error information is printed within a section with name " ERROR ".
−show_format
Show information about the container format of the input multimedia stream.
All the container format information is printed within a section with name " FORMAT ".
−show_format_entry name
Like −show_format, but only prints the specified entry of the container format information, rather than all. This option may be given more than once, then all specified entries will be shown.
−show_packets
Show information about each packet contained in the input multimedia stream.
The information for each single packet is printed within a dedicated section with name " PACKET ".
−show_frames
Show information about each frame contained in the input multimedia stream.
The information for each single frame is printed within a dedicated section with name " FRAME ".
−show_streams
Show information about each media stream contained in the input multimedia stream.
Each media stream information is printed within a dedicated section with name " STREAM ".
−count_frames
Count the number of frames per stream and report it in the corresponding stream section.
−count_packets
Count the number of packets per stream and report it in the corresponding stream section.
−show_private_data, −private
Show private data, that is data depending on the format of the particular shown element. This option is enabled by default, but you may need to disable it for specific uses, for example when creating XSD-compliant XML output.
−show_program_version
Show information related to program version.
Version information is printed within a section with name " PROGRAM_VERSION ".
−show_library_versions
Show information related to library versions.
Version information for each library is printed within a section with name " LIBRARY_VERSION ".
−show_versions
Show information related to program and library versions. This is the equivalent of setting both −show_program_version and −show_library_versions options.
−bitexact
Force bitexact output, useful to produce output which is not dependent on the specific build.
−i input_file
Read input_file.
A writer defines the output format adopted by ffprobe, and will be used for printing all the parts of the output.
A writer may accept one or more arguments, which specify the options to adopt.
A description of the currently available writers follows.
default
Default format.
Print each section in the form:
[SECTION]
key1=val1
...
keyN=valN
[/SECTION]
Metadata tags are printed as a line in the corresponding FORMAT or STREAM section, and are prefixed by the string " TAG: ".
This writer accepts options as a list of key=value pairs, separated by ":".
A description
of the accepted options follows.
nokey, nk
If set to 1 specify not to print the key of each field. Default value is 0.
noprint_wrappers, nw
If set to 1 specify not to print the section header and footer. Default value is 0.
compact,
csv
Compact and CSV format.
The "csv" writer is equivalent to "compact", but supports different defaults.
Each section is printed on a single line. If no option is specifid, the output has the form:
section|key1=val1| ... |keyN=valN
Metadata tags are printed in the corresponding "format" or "stream" section. A metadata tag key, if printed, is prefixed by the string "tag:".
This writer accepts options as a list of key=value pairs, separated by ":".
The description
of the accepted options follows.
item_sep, s
Specify the character to use for separating fields in the output line. It must be a single printable character, it is "|" by default ("," for the "csv" writer).
nokey, nk
If set to 1 specify not to print the key of each field. Its default value is 0 (1 for the "csv" writer).
escape, e
Set the escape mode to use, default to "c" ("csv" for the "csv" writer).
It can assume one of the following values:
|
c |
Perform C−like escaping. Strings containing a newline (’\n’), carriage return (’\r’), a tab (’\t’), a form feed (’\f’), the escaping character (’\’) or the item separator character SEP are escaped using C−like fashioned escaping, so that a newline is converted to the sequence "\n", a carriage return to "\r", ’\’ to "\\" and the separator SEP is converted to "\ SEP ". | ||
|
csv |
Perform CSV-like escaping, as described in RFC4180 . Strings containing a newline (’\n’), a carriage return (’\r’), a double quote (’"’), or SEP are enclosed in double-quotes. |
none
Perform no escaping.
print_section, p
Print the section name at the begin of each line if the value is 1, disable it with value set to 0. Default value is 1.
flat
Flat format.
A free-form output where each line contains an explicit key=value, such as "streams.stream.3.tags.foo=bar". The output is shell escaped, so it can be directly embedded in sh scripts as long as the separator character is an alphanumeric character or an underscore (see sep_char option).
This writer accepts options as a list of key=value pairs, separated by ":".
The description
of the accepted options follows.
sep_char, s
Separator character used to separate the chapter, the section name, IDs and potential tags in the printed field key.
Default value is ’.’.
hierarchical, h
Specify if the section name specification should be hierarchical. If set to 1, and if there is more than one section in the current chapter, the section name will be prefixed by the name of the chapter. A value of 0 will disable this behavior.
Default value is 1.
ini
INI format output.
Print output in an INI based format.
The following conventions are adopted:
|
• |
all key and values are UTF−8 | ||
|
• |
’.’ is the subgroup separator | ||
|
• |
newline, ’\t’, ’\f’, ’\b’ and the following characters are escaped | ||
|
• |
’\’ is the escape character | ||
|
• |
’#’ is the comment indicator | ||
|
• |
’=’ is the key/value separator | ||
|
• |
’:’ is not used but usually parsed as key/value separator |
This writer accepts options as a list of key=value pairs, separated by ":".
The description
of the accepted options follows.
hierarchical, h
Specify if the section name specification should be hierarchical. If set to 1, and if there is more than one section in the current chapter, the section name will be prefixed by the name of the chapter. A value of 0 will disable this behavior.
Default value is 1.
json
JSON based format.
Each section is printed using JSON notation.
This writer accepts options as a list of key=value pairs, separated by ":".
The description
of the accepted options follows.
compact, c
If set to 1 enable compact output, that is each section will be printed on a single line. Default value is 0.
For more information about JSON , see <http://www.json.org/>.
xml
XML based format.
The XML output is described in the XML schema description file ffprobe.xsd installed in the FFmpeg datadir.
An updated version of the schema can be retrieved at the url <http://www.ffmpeg.org/schema/ffprobe.xsd>, which redirects to the latest schema committed into the FFmpeg development source code tree.
Note that the output issued will be compliant to the ffprobe.xsd schema only when no special global output options (unit, prefix, byte_binary_prefix, sexagesimal etc.) are specified.
This writer accepts options as a list of key=value pairs, separated by ":".
The description
of the accepted options follows.
fully_qualified, q
If set to 1 specify if the output should be fully qualified. Default value is 0. This is required for generating an XML file which can be validated through an XSD file.
xsd_compliant, x
If set to 1 perform more checks for ensuring that the output is XSD compliant. Default value is 0. This option automatically sets fully_qualified to 1.
For more information about the XML format, see <http://www.w3.org/XML/>.
ffprobe supports Timecode extraction:
|
• |
MPEG1/2 timecode is extracted from the GOP , and is available in the video stream details (−show_streams, see timecode). | ||
|
• |
MOV timecode is extracted from tmcd track, so is available in the tmcd stream metadata (−show_streams, see TAG:timecode). | ||
|
• |
DV , GXF and AVI timecodes are available in format metadata (−show_format, see TAG:timecode). |
When evaluating specific formats, FFmpeg uses internal library parsing functions, shared by the tools. This section documents the syntax of some of these formats.
Date
The accepted syntax is:
[(YYYY−MM−DD|YYYYMMDD)[T|t| ]]((HH:MM:SS[.m...]]])|(HHMMSS[.m...]]]))[Z]
now
If the value is "now" it takes the current time.
Time is local time unless Z is appended, in which case it is interpreted as UTC . If the year-month-day part is not specified it takes the current year-month-day.
Time
duration
The accepted syntax is:
[−]HH:MM:SS[.m...]
[−]S+[.m...]
HH expresses the number of hours, MM the number a of minutes and SS the number of seconds.
Video
size
Specify the size of the sourced video, it may be a string of
the form widthxheight, or the name of a size
abbreviation.
The following
abbreviations are recognized:
sqcif
128x96
qcif
176x144
|
cif |
352x288 |
4cif
704x576
16cif
1408x1152
qqvga
160x120
qvga
320x240
|
vga |
640x480 |
svga
800x600
|
xga |
1024x768 |
uxga
1600x1200
qxga
2048x1536
sxga
1280x1024
qsxga
2560x2048
hsxga
5120x4096
wvga
852x480
wxga
1366x768
wsxga
1600x1024
wuxga
1920x1200
woxga
2560x1600
wqsxga
3200x2048
wquxga
3840x2400
whsxga
6400x4096
whuxga
7680x4800
|
cga |
320x200 |
|||
|
ega |
640x350 |
hd480
852x480
hd720
1280x720
hd1080
1920x1080
Video
rate
Specify the frame rate of a video, expressed as the number
of frames generated per second. It has to be a string in the
format frame_rate_num/frame_rate_den, an
integer number, a float number or a valid video frame rate
abbreviation.
The following
abbreviations are recognized:
ntsc
30000/1001
|
pal |
25/1 |
qntsc
30000/1
qpal
25/1
sntsc
30000/1
spal
25/1
film
24/1
ntsc-film
24000/1
Ratio
A ratio can be expressed as an expression, or in the form
numerator:denominator.
Note that a ratio with infinite (1/0) or negative value is considered valid, so you should check on the returned value if you want to exclude those values.
The undefined value can be expressed using the "0:0" string.
Color
It can be the name of a color (case insensitive match) or a
[0x|#]RRGGBB[ AA ] sequence, possibly
followed by "@" and a string representing the
alpha component.
The alpha component may be a string composed by "0x" followed by an hexadecimal number or a decimal number between 0.0 and 1.0, which represents the opacity value (0x00/0.0 means completely transparent, 0xff/1.0 completely opaque). If the alpha component is not specified then 0xff is assumed.
The string "random" will result in a random color.
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 "−codecs" of the ff* tools will display the list of enabled decoders.
A description of some of the currently available video decoders follows.
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 |
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.
Demuxers are configured elements in FFmpeg which allow to read the multimedia streams from a particular type of file.
When you configure your FFmpeg build, all the supported demuxers are enabled by default. You can list all available ones using the configure option "−−list−demuxers".
You can disable all the demuxers using the configure option "−−disable−demuxers", and selectively enable a single demuxer with the option "−−enable−demuxer= DEMUXER ", or disable it with the option "−−disable−demuxer= DEMUXER ".
The option "−formats" of the ff* tools will display the list of enabled demuxers.
The description of some of the currently available demuxers follows.
image2
Image file demuxer.
This demuxer reads from a list of image files specified by a pattern. The syntax and meaning of the pattern is specified by the option pattern_type.
The pattern may contain a suffix which is used to automatically determine the format of the images contained in the files.
The size, the pixel format, and the format of each image must be the same for all the files in the sequence.
This demuxer
accepts the following options:
framerate
Set the framerate for the video stream. It defaults to 25.
loop
If set to 1, loop over the input. Default value is 0.
pattern_type
Select the pattern type used to interpret the provided filename.
pattern_type
accepts one of the following values.
sequence
Select a sequence pattern type, used to specify a sequence of files indexed by sequential numbers.
A sequence pattern may contain the string "%d" or "%0Nd", which specifies the position of the characters representing a sequential number in each filename matched by the pattern. If the form "%d0Nd" is used, the string representing the number in each filename is 0−padded and N is the total number of 0−padded digits representing the number. The literal character ’%’ can be specified in the pattern with the string "%%".
If the sequence pattern contains "%d" or "%0Nd", the first filename of the file list specified by the pattern must contain a number inclusively contained between start_number and start_number+start_number_range−1, and all the following numbers must be sequential.
For example the pattern "img−%03d.bmp" will match a sequence of filenames of the form img−001.bmp, img−002.bmp, ..., img−010.bmp, etc.; the pattern "i%%m%%g−%d.jpg" will match a sequence of filenames of the form i%m%g−1.jpg, i%m%g−2.jpg, ..., i%m%g−10.jpg, etc.
Note that the pattern must not necessarily contain "%d" or "%0Nd", for example to convert a single image file img.jpeg you can employ the command:
ffmpeg −i img.jpeg img.png
glob
Select a glob wildcard pattern type.
The pattern is interpreted like a "glob()" pattern. This is only selectable if libavformat was compiled with globbing support.
glob_sequence (deprecated, will be removed)
Select a mixed glob wildcard/sequence pattern.
If your version of libavformat was compiled with globbing support, and the provided pattern contains at least one glob meta character among "%*?[]{}" that is preceded by an unescaped "%", the pattern is interpreted like a "glob()" pattern, otherwise it is interpreted like a sequence pattern.
All glob special characters "%*?[]{}" must be prefixed with "%". To escape a literal "%" you shall use "%%".
For example the pattern "foo−%*.jpeg" will match all the filenames prefixed by "foo−" and terminating with ".jpeg", and "foo−%?%?%?.jpeg" will match all the filenames prefixed with "foo−", followed by a sequence of three characters, and terminating with ".jpeg".
This pattern type is deprecated in favor of glob and sequence.
Default value is glob_sequence.
pixel_format
Set the pixel format of the images to read. If not specified the pixel format is guessed from the first image file in the sequence.
start_number
Set the index of the file matched by the image file pattern to start to read from. Default value is 0.
start_number_range
Set the index interval range to check when looking for the first image file in the sequence, starting from start_number. Default value is 5.
video_size
Set the video size of the images to read. If not specified the video size is guessed from the first image file in the sequence.
Examples
|
• |
Use ffmpeg for creating a video from the images in the file sequence img−001.jpeg, img−002.jpeg, ..., assuming an input frame rate of 10 frames per second: |
ffmpeg −i 'img−%03d.jpeg' −r 10 out.mkv
|
• |
As above, but start by reading from a file with index 100 in the sequence: |
ffmpeg −start_number 100 −i 'img−%03d.jpeg' −r 10 out.mkv
|
• |
Read images matching the "*.png" glob pattern , that is all the files terminating with the ".png" suffix: |
ffmpeg −pattern_type glob −i "*.png" −r 10 out.mkv
applehttp
Apple HTTP Live Streaming demuxer.
This demuxer presents all AVStreams from all variant streams. The id field is set to the bitrate variant index number. By setting the discard flags on AVStreams (by pressing ’a’ or ’v’ in ffplay), the caller can decide which variant streams to actually receive. The total bitrate of the variant that the stream belongs to is available in a metadata key named "variant_bitrate".
sbg
SBaGen script demuxer.
This demuxer reads the script language used by SBaGen <http://uazu.net/sbagen/> to generate binaural beats sessions. A SBG script looks like that:
−SE
a: 300−2.5/3 440+4.5/0
b: 300−2.5/0 440+4.5/3
off: −
NOW == a
+0:07:00 == b
+0:14:00 == a
+0:21:00 == b
+0:30:00 off
A SBG script can mix absolute and relative timestamps. If the script uses either only absolute timestamps (including the script start time) or only relative ones, then its layout is fixed, and the conversion is straightforward. On the other hand, if the script mixes both kind of timestamps, then the NOW reference for relative timestamps will be taken from the current time of day at the time the script is read, and the script layout will be frozen according to that reference. That means that if the script is directly played, the actual times will match the absolute timestamps up to the sound controller’s clock accuracy, but if the user somehow pauses the playback or seeks, all times will be shifted accordingly.
Protocols are configured elements in FFmpeg which allow to access resources which require the use of a particular protocol.
When you configure your FFmpeg build, all the supported protocols are enabled by default. You can list all available ones using the configure option "−−list−protocols".
You can disable all the protocols using the configure option "−−disable−protocols", and selectively enable a protocol using the option "−−enable−protocol= PROTOCOL ", or you can disable a particular protocol using the option "−−disable−protocol= PROTOCOL ".
The option "−protocols" of the ff* tools will display the list of supported protocols.
A description of the currently available protocols follows.
bluray
Read BluRay playlist.
The accepted
options are:
angle
BluRay angle
chapter
Start chapter (1...N)
playlist
Playlist to read ( BDMV/PLAYLIST/ ?????.mpls)
Examples:
Read longest playlist from BluRay mounted to /mnt/bluray:
bluray:/mnt/bluray
Read angle 2 of playlist 4 from BluRay mounted to /mnt/bluray, start from chapter 2:
−playlist 4 −angle 2 −chapter 2 bluray:/mnt/bluray
concat
Physical concatenation protocol.
Allow to read and seek from many resource in sequence as if they were a unique resource.
A URL accepted by this protocol has the syntax:
concat:<URL1>|<URL2>|...|<URLN>
where URL1 , URL2 , ..., URLN are the urls of the resource to be concatenated, each one possibly specifying a distinct protocol.
For example to read a sequence of files split1.mpeg, split2.mpeg, split3.mpeg with ffplay use the command:
ffplay concat:split1.mpeg\|split2.mpeg\|split3.mpeg
Note that you may need to escape the character "|" which is special for many shells.
file
File access protocol.
Allow to read from or read to a file.
For example to read from a file input.mpeg with ffmpeg use the command:
ffmpeg −i file:input.mpeg output.mpeg
The ff* tools default to the file protocol, that is a resource specified with the name " FILE .mpeg" is interpreted as the URL "file:FILE.mpeg".
gopher
Gopher protocol.
hls
Read Apple HTTP Live Streaming compliant
segmented stream as a uniform one. The M3U8 playlists
describing the segments can be remote HTTP
resources or local files, accessed using the standard file
protocol. The nested protocol is declared by specifying
"+proto" after the hls URI
scheme name, where proto is either "file"
or "http".
hls+http://host/path/to/remote/resource.m3u8
hls+file://path/to/local/resource.m3u8
Using this protocol is discouraged − the hls demuxer should work just as well (if not, please report the issues) and is more complete. To use the hls demuxer instead, simply use the direct URLs to the m3u8 files.
http
HTTP (Hyper Text Transfer Protocol).
mmst
MMS (Microsoft Media Server) protocol over
TCP .
mmsh
MMS (Microsoft Media Server) protocol over
HTTP .
The required syntax is:
mmsh://<server>[:<port>][/<app>][/<playpath>]
md5
MD5 output protocol.
Computes the MD5 hash of the data to be written, and on close writes this to the designated output or stdout if none is specified. It can be used to test muxers without writing an actual file.
Some examples follow.
# Write the MD5 hash of the encoded AVI file to the file output.avi.md5.
ffmpeg −i input.flv −f avi −y md5:output.avi.md5
# Write the MD5 hash of the encoded AVI file to stdout.
ffmpeg −i input.flv −f avi −y md5:
Note that some formats (typically MOV ) require the output protocol to be seekable, so they will fail with the MD5 output protocol.
pipe
UNIX pipe access protocol.
Allow to read and write from UNIX pipes.
The accepted syntax is:
pipe:[<number>]
number is the number corresponding to the file descriptor of the pipe (e.g. 0 for stdin, 1 for stdout, 2 for stderr). If number is not specified, by default the stdout file descriptor will be used for writing, stdin for reading.
For example to read from stdin with ffmpeg:
cat test.wav | ffmpeg −i pipe:0
# ...this is the same as...
cat test.wav | ffmpeg −i pipe:
For writing to stdout with ffmpeg:
ffmpeg −i test.wav −f avi pipe:1 | cat > test.avi
# ...this is the same as...
ffmpeg −i test.wav −f avi pipe: | cat > test.avi
Note that some formats (typically MOV ), require the output protocol to be seekable, so they will fail with the pipe output protocol.
rtmp
Real-Time Messaging Protocol.
The Real-Time Messaging Protocol ( RTMP ) is used for streaming multimedia content across a TCP/IP network.
The required syntax is:
rtmp://<server>[:<port>][/<app>][/<instance>][/<playpath>]
The accepted
parameters are:
server
The address of the RTMP server.
port
The number of the TCP port to use (by default is 1935).
|
app |
It is the name of the application to access. It usually corresponds to the path where the application is installed on the RTMP server (e.g. /ondemand/, /flash/live/, etc.). You can override the value parsed from the URI through the "rtmp_app" option, too. |
playpath
It is the path or name of the resource to play with reference to the application specified in app, may be prefixed by "mp4:". You can override the value parsed from the URI through the "rtmp_playpath" option, too.
listen
Act as a server, listening for an incoming connection.
timeout
Maximum time to wait for the incoming connection. Implies listen.
Additionally,
the following parameters can be set via command line options
(or in code via "AVOption"s):
rtmp_app
Name of application to connect on the RTMP server. This option overrides the parameter specified in the URI .
rtmp_buffer
Set the client buffer time in milliseconds. The default is 3000.
rtmp_conn
Extra arbitrary AMF connection parameters, parsed from a string, e.g. like "B:1 S:authMe O:1 NN:code:1.23 NS:flag:ok O:0". Each value is prefixed by a single character denoting the type, B for Boolean, N for number, S for string, O for object, or Z for null, followed by a colon. For Booleans the data must be either 0 or 1 for FALSE or TRUE , respectively. Likewise for Objects the data must be 0 or 1 to end or begin an object, respectively. Data items in subobjects may be named, by prefixing the type with ’N’ and specifying the name before the value (i.e. "NB:myFlag:1"). This option may be used multiple times to construct arbitrary AMF sequences.
rtmp_flashver
Version of the Flash plugin used to run the SWF player. The default is LNX 9,0,124,2.
rtmp_flush_interval
Number of packets flushed in the same request ( RTMPT only). The default is 10.
rtmp_live
Specify that the media is a live stream. No resuming or seeking in live streams is possible. The default value is "any", which means the subscriber first tries to play the live stream specified in the playpath. If a live stream of that name is not found, it plays the recorded stream. The other possible values are "live" and "recorded".
rtmp_pageurl
URL of the web page in which the media was embedded. By default no value will be sent.
rtmp_playpath
Stream identifier to play or to publish. This option overrides the parameter specified in the URI .
rtmp_subscribe
Name of live stream to subscribe to. By default no value will be sent. It is only sent if the option is specified or if rtmp_live is set to live.
rtmp_swfhash
SHA256 hash of the decompressed SWF file (32 bytes).
rtmp_swfsize
Size of the decompressed SWF file, required for SWFVerification.
rtmp_swfurl
URL of the SWF player for the media. By default no value will be sent.
rtmp_swfverify
URL to player swf file, compute hash/size automatically.
rtmp_tcurl
URL of the target stream. Defaults to proto://host[:port]/app.
For example to read with ffplay a multimedia resource named "sample" from the application "vod" from an RTMP server "myserver":
ffplay rtmp://myserver/vod/sample
rtmpe
Encrypted Real-Time Messaging Protocol.
The Encrypted Real-Time Messaging Protocol ( RTMPE ) is used for streaming multimedia content within standard cryptographic primitives, consisting of Diffie-Hellman key exchange and HMACSHA256 , generating a pair of RC4 keys.
rtmps
Real-Time Messaging Protocol over a secure
SSL connection.
The Real-Time Messaging Protocol ( RTMPS ) is used for streaming multimedia content across an encrypted connection.
rtmpt
Real-Time Messaging Protocol tunneled through
HTTP .
The Real-Time Messaging Protocol tunneled through HTTP ( RTMPT ) is used for streaming multimedia content within HTTP requests to traverse firewalls.
rtmpte
Encrypted Real-Time Messaging Protocol tunneled through
HTTP .
The Encrypted Real-Time Messaging Protocol tunneled through HTTP ( RTMPTE ) is used for streaming multimedia content within HTTP requests to traverse firewalls.
rtmpts
Real-Time Messaging Protocol tunneled through
HTTPS .
The Real-Time Messaging Protocol tunneled through HTTPS ( RTMPTS ) is used for streaming multimedia content within HTTPS requests to traverse firewalls.
rtmp, rtmpe,
rtmps, rtmpt, rtmpte
Real-Time Messaging Protocol and its variants supported
through librtmp.
Requires the presence of the librtmp headers and library during configuration. You need to explicitly configure the build with "−−enable−librtmp". If enabled this will replace the native RTMP protocol.
This protocol provides most client functions and a few server functions needed to support RTMP , RTMP tunneled in HTTP ( RTMPT ), encrypted RTMP ( RTMPE ), RTMP over SSL/TLS ( RTMPS ) and tunneled variants of these encrypted types ( RTMPTE , RTMPTS ).
The required syntax is:
<rtmp_proto>://<server>[:<port>][/<app>][/<playpath>] <options>
where rtmp_proto is one of the strings "rtmp", "rtmpt", "rtmpe", "rtmps", "rtmpte", "rtmpts" corresponding to each RTMP variant, and server, port, app and playpath have the same meaning as specified for the RTMP native protocol. options contains a list of space-separated options of the form key=val.
See the librtmp manual page (man 3 librtmp) for more information.
For example, to stream a file in real-time to an RTMP server using ffmpeg:
ffmpeg −re −i myfile −f flv rtmp://myserver/live/mystream
To play the same stream using ffplay:
ffplay "rtmp://myserver/live/mystream live=1"
rtp
Real-Time Protocol.
rtsp
RTSP is not technically a protocol handler in
libavformat, it is a demuxer and muxer. The demuxer supports
both normal RTSP (with data transferred over
RTP ; this is used by e.g. Apple and
Microsoft) and Real-RTSP (with data transferred over
RDT ).
The muxer can be used to send a stream using RTSP ANNOUNCE to a server supporting it (currently Darwin Streaming Server and Mischa Spiegelmock’s <http://github.com/revmischa/rtsp−server>).
The required syntax for a RTSP url is:
rtsp://<hostname>[:<port>]/<path>
The following options (set on the ffmpeg/ffplay command line, or set in code via "AVOption"s or in "avformat_open_input"), are supported:
Flags for "rtsp_transport":
|
udp |
Use UDP as lower transport protocol. | ||
|
tcp |
Use TCP (interleaving within the RTSP control channel) as lower transport protocol. |
udp_multicast
Use UDP multicast as lower transport protocol.
http
Use HTTP tunneling as lower transport protocol, which is useful for passing proxies.
Multiple lower transport protocols may be specified, in that case they are tried one at a time (if the setup of one fails, the next one is tried). For the muxer, only the "tcp" and "udp" options are supported.
Flags for
"rtsp_flags":
filter_src
Accept packets only from negotiated peer address and port.
listen
Act as a server, listening for an incoming connection.
When receiving data over UDP , the demuxer tries to reorder received packets (since they may arrive out of order, or packets may get lost totally). This can be disabled by setting the maximum demuxing delay to zero (via the "max_delay" field of AVFormatContext).
When watching multi-bitrate Real-RTSP streams with ffplay, the streams to display can be chosen with "−vst" n and "−ast" n for video and audio respectively, and can be switched on the fly by pressing "v" and "a".
Example command lines:
To watch a stream over UDP , with a max reordering delay of 0.5 seconds:
ffplay −max_delay 500000 −rtsp_transport udp rtsp://server/video.mp4
To watch a stream tunneled over HTTP:
ffplay −rtsp_transport http rtsp://server/video.mp4
To send a stream in realtime to a RTSP server, for others to watch:
ffmpeg −re −i <input> −f rtsp −muxdelay 0.1 rtsp://server/live.sdp
To receive a stream in realtime:
ffmpeg −rtsp_flags listen −i rtsp://ownaddress/live.sdp <output>
sap
Session Announcement Protocol ( RFC 2974).
This is not technically a protocol handler in libavformat,
it is a muxer and demuxer. It is used for signalling of
RTP streams, by announcing the
SDP for the streams regularly on a separate
port.
Muxer
The syntax for a SAP url given to the muxer is:
sap://<destination>[:<port>][?<options>]
The
RTP packets are sent to destination on
port port, or to port 5004 if no port is specified.
options is a
"&"−separated list. The
following options are supported:
announce_addr=address
Specify the destination IP address for sending the announcements to. If omitted, the announcements are sent to the commonly used SAP announcement multicast address 224.2.127.254 (sap.mcast.net), or ff0e::2:7ffe if destination is an IPv6 address.
announce_port=port
Specify the port to send the announcements on, defaults to 9875 if not specified.
ttl=ttl
Specify the time to live value for the announcements and RTP packets, defaults to 255.
same_port=0|1
If set to 1, send all RTP streams on the same port pair. If zero (the default), all streams are sent on unique ports, with each stream on a port 2 numbers higher than the previous. VLC/Live555 requires this to be set to 1, to be able to receive the stream. The RTP stack in libavformat for receiving requires all streams to be sent on unique ports.
Example command lines follow.
To broadcast a stream on the local subnet, for watching in VLC:
ffmpeg −re −i <input> −f sap sap://224.0.0.255?same_port=1
Similarly, for watching in ffplay:
ffmpeg −re −i <input> −f sap sap://224.0.0.255
And for watching in ffplay, over IPv6:
ffmpeg −re −i <input> −f sap sap://[ff0e::1:2:3:4]
Demuxer
The syntax for a SAP url given to the demuxer is:
sap://[<address>][:<port>]
address is the multicast address to listen for announcements on, if omitted, the default 224.2.127.254 (sap.mcast.net) is used. port is the port that is listened on, 9875 if omitted.
The demuxers listens for announcements on the given address and port. Once an announcement is received, it tries to receive that particular stream.
Example command lines follow.
To play back the first stream announced on the normal SAP multicast address:
ffplay sap://
To play back the first stream announced on one the default IPv6 SAP multicast address:
ffplay sap://[ff0e::2:7ffe]
tcp
Trasmission Control Protocol.
The required syntax for a TCP url is:
tcp://<hostname>:<port>[?<options>]
listen
Listen for an incoming connection
timeout=microseconds
In read mode: if no data arrived in more than this time interval, raise error. In write mode: if socket cannot be written in more than this time interval, raise error. This also sets timeout on TCP connection establishing.
ffmpeg −i <input> −f <format> tcp://<hostname>:<port>?listen
ffplay tcp://<hostname>:<port>
tls
Transport Layer Security/Secure Sockets Layer
The required syntax for a TLS/SSL url is:
tls://<hostname>:<port>[?<options>]
listen
Act as a server, listening for an incoming connection.
cafile=filename
Certificate authority file. The file must be in OpenSSL PEM format.
cert=filename
Certificate file. The file must be in OpenSSL PEM format.
key=filename
Private key file.
verify=0|1
Verify the peer’s certificate.
Example command lines:
To create a TLS/SSL server that serves an input stream.
ffmpeg −i <input> −f <format> tls://<hostname>:<port>?listen&cert=<server.crt>&key=<server.key>
To play back a stream from the TLS/SSL server using ffplay:
ffplay tls://<hostname>:<port>
udp
User Datagram Protocol.
The required syntax for a UDP url is:
udp://<hostname>:<port>[?<options>]
options contains a list of &−separated options of the form key=val.
In case threading is enabled on the system, a circular buffer is used to store the incoming data, which allows to reduce loss of data due to UDP socket buffer overruns. The fifo_size and overrun_nonfatal options are related to this buffer.
The list of
supported options follows.
buffer_size=size
Set the UDP socket buffer size in bytes. This is used both for the receiving and the sending buffer size.
localport=port
Override the local UDP port to bind with.
localaddr=addr
Choose the local IP address. This is useful e.g. if sending multicast and the host has multiple interfaces, where the user can choose which interface to send on by specifying the IP address of that interface.
pkt_size=size
Set the size in bytes of UDP packets.
reuse=1|0
Explicitly allow or disallow reusing UDP sockets.
ttl=ttl
Set the time to live value (for multicast only).
connect=1|0
Initialize the UDP socket with "connect()". In this case, the destination address can’t be changed with ff_udp_set_remote_url later. If the destination address isn’t known at the start, this option can be specified in ff_udp_set_remote_url, too. This allows finding out the source address for the packets with getsockname, and makes writes return with AVERROR ( ECONNREFUSED ) if "destination unreachable" is received. For receiving, this gives the benefit of only receiving packets from the specified peer address/port.
sources=address[,address]
Only receive packets sent to the multicast group from one of the specified sender IP addresses.
block=address[,address]
Ignore packets sent to the multicast group from the specified sender IP addresses.
fifo_size=units
Set the UDP receiving circular buffer size, expressed as a number of packets with size of 188 bytes. If not specified defaults to 7*4096.
overrun_nonfatal=1|0
Survive in case of UDP receiving circular buffer overrun. Default value is 0.
timeout=microseconds
In read mode: if no data arrived in more than this time interval, raise error.
Some usage examples of the UDP protocol with ffmpeg follow.
To stream over UDP to a remote endpoint:
ffmpeg −i <input> −f <format> udp://<hostname>:<port>
To stream in mpegts format over UDP using 188 sized UDP packets, using a large input buffer:
ffmpeg −i <input> −f mpegts udp://<hostname>:<port>?pkt_size=188&buffer_size=65535
To receive over UDP from a remote endpoint:
ffmpeg −i udp://[<multicast−address>]:<port>
Input devices are configured elements in FFmpeg which allow to access the data coming from a multimedia device attached to your system.
When you configure your FFmpeg build, all the supported input devices are enabled by default. You can list all available ones using the configure option "−−list−indevs".
You can disable all the input devices using the configure option "−−disable−indevs", and selectively enable an input device using the option "−−enable−indev= INDEV ", or you can disable a particular input device using the option "−−disable−indev= INDEV ".
The option "−formats" of the ff* tools will display the list of supported input devices (amongst the demuxers).
A description of the currently available input devices follows.
alsa
ALSA (Advanced Linux Sound Architecture) input
device.
To enable this input device during configuration you need libasound installed on your system.
This device allows capturing from an ALSA device. The name of the device to capture has to be an ALSA card identifier.
An ALSA identifier has the syntax:
hw:<CARD>[,<DEV>[,<SUBDEV>]]
where the DEV and SUBDEV components are optional.
The three arguments (in order: CARD , DEV , SUBDEV ) specify card number or identifier, device number and subdevice number (−1 means any).
To see the list of cards currently recognized by your system check the files /proc/asound/cards and /proc/asound/devices.
For example to capture with ffmpeg from an ALSA device with card id 0, you may run the command:
ffmpeg −f alsa −i hw:0 alsaout.wav
For more information see: <http://www.alsa−project.org/alsa−doc/alsa−lib/pcm.html>
bktr
BSD video input device.
dshow
Windows DirectShow input device.
DirectShow support is enabled when FFmpeg is built with the mingw−w64 project. Currently only audio and video devices are supported.
Multiple devices may be opened as separate inputs, but they may also be opened on the same input, which should improve synchronism between them.
The input name should be in the format:
<TYPE>=<NAME>[:<TYPE>=<NAME>]
where TYPE can be either audio or video, and NAME is the device’s name.
Options
If no options
are specified, the device’s defaults are used. If the
device does not support the requested options, it will fail
to open.
video_size
Set the video size in the captured video.
framerate
Set the framerate in the captured video.
sample_rate
Set the sample rate (in Hz) of the captured audio.
sample_size
Set the sample size (in bits) of the captured audio.
channels
Set the number of channels in the captured audio.
list_devices
If set to true, print a list of devices and exit.
list_options
If set to true, print a list of selected device’s options and exit.
video_device_number
Set video device number for devices with same name (starts at 0, defaults to 0).
audio_device_number
Set audio device number for devices with same name (starts at 0, defaults to 0).
pixel_format
Select pixel format to be used by DirectShow. This may only be set when the video codec is not set or set to rawvideo.
audio_buffer_size
Set audio device buffer size in milliseconds (which can directly impact latency, depending on the device). Defaults to using the audio device’s default buffer size (typically some multiple of 500ms). Setting this value too low can degrade performance. See also <http://msdn.microsoft.com/en−us/library/windows/desktop/dd377582(v=vs.85).aspx>
Examples
|
• |
Print the list of DirectShow supported devices and exit: |
$ ffmpeg −list_devices true −f dshow −i dummy
|
• |
Open video device Camera: |
$ ffmpeg −f dshow −i video="Camera"
|
• |
Open second video device with name Camera: |
$ ffmpeg −f dshow −video_device_number 1 −i video="Camera"
|
• |
Open video device Camera and audio device Microphone: |
$ ffmpeg −f dshow −i video="Camera":audio="Microphone"
|
• |
Print the list of supported options in selected device and exit: |
$ ffmpeg −list_options true −f dshow −i video="Camera"
dv1394
Linux DV 1394 input device.
fbdev
Linux framebuffer input device.
The Linux framebuffer is a graphic hardware-independent abstraction layer to show graphics on a computer monitor, typically on the console. It is accessed through a file device node, usually /dev/fb0.
For more detailed information read the file Documentation/fb/framebuffer.txt included in the Linux source tree.
To record from the framebuffer device /dev/fb0 with ffmpeg:
ffmpeg −f fbdev −r 10 −i /dev/fb0 out.avi
You can take a single screenshot image with the command:
ffmpeg −f fbdev −frames:v 1 −r 1 −i /dev/fb0 screenshot.jpeg
See also <http://linux−fbdev.sourceforge.net/>, and fbset(1).
iec61883
FireWire DV/HDV input device using
libiec61883.
To enable this input device, you need libiec61883, libraw1394 and libavc1394 installed on your system. Use the configure option "−−enable−libiec61883" to compile with the device enabled.
The iec61883 capture device supports capturing from a video device connected via IEEE1394 (FireWire), using libiec61883 and the new Linux FireWire stack (juju). This is the default DV/HDV input method in Linux Kernel 2.6.37 and later, since the old FireWire stack was removed.
Specify the FireWire port to be used as input file, or "auto" to choose the first port connected.
Options
dvtype
Override autodetection of DV/HDV . This should only be used if auto detection does not work, or if usage of a different device type should be prohibited. Treating a DV device as HDV (or vice versa) will not work and result in undefined behavior. The values auto, dv and hdv are supported.
dvbuffer
Set maxiumum size of buffer for incoming data, in frames. For DV , this is an exact value. For HDV , it is not frame exact, since HDV does not have a fixed frame size.
Examples
|
• |
Grab and show the input of a FireWire DV/HDV device. |
ffplay −f iec61883 −i auto
|
• |
Grab and record the input of a FireWire DV/HDV device, using a packet buffer of 100000 packets if the source is HDV . |
ffmpeg −f iec61883 −i auto −hdvbuffer 100000 out.mpg
jack
JACK input device.
To enable this input device during configuration you need libjack installed on your system.
A JACK input device creates one or more JACK writable clients, one for each audio channel, with name client_name:input_N, where client_name is the name provided by the application, and N is a number which identifies the channel. Each writable client will send the acquired data to the FFmpeg input device.
Once you have created one or more JACK readable clients, you need to connect them to one or more JACK writable clients.
To connect or disconnect JACK clients you can use the jack_connect and jack_disconnect programs, or do it through a graphical interface, for example with qjackctl.
To list the JACK clients and their properties you can invoke the command jack_lsp.
Follows an example which shows how to capture a JACK readable client with ffmpeg.
# Create a JACK writable client with name "ffmpeg".
$ ffmpeg −f jack −i ffmpeg −y out.wav
# Start the sample jack_metro readable client.
$ jack_metro −b 120 −d 0.2 −f 4000
# List the current JACK clients.
$ jack_lsp −c
system:capture_1
system:capture_2
system:playback_1
system:playback_2
ffmpeg:input_1
metro:120_bpm
# Connect metro to the ffmpeg writable client.
$ jack_connect metro:120_bpm ffmpeg:input_1
For more information read: <http://jackaudio.org/>
lavfi
Libavfilter input virtual device.
This input device reads data from the open output pads of a libavfilter filtergraph.
For each filtergraph open output, the input device will create a corresponding stream which is mapped to the generated output. Currently only video data is supported. The filtergraph is specified through the option graph.
Options
graph
Specify the filtergraph to use as input. Each video open output must be labelled by a unique string of the form "outN", where N is a number starting from 0 corresponding to the mapped input stream generated by the device. The first unlabelled output is automatically assigned to the "out0" label, but all the others need to be specified explicitly.
If not specified defaults to the filename specified for the input device.
Examples
|
• |
Create a color video stream and play it back with ffplay: |
ffplay −f lavfi −graph "color=pink [out0]" dummy
|
• |
As the previous example, but use filename for specifying the graph description, and omit the "out0" label: |
ffplay −f lavfi color=pink
|
• |
Create three different video test filtered sources and play them: |
ffplay −f lavfi −graph "testsrc [out0]; testsrc,hflip [out1]; testsrc,negate [out2]" test3
|
• |
Read an audio stream from a file using the amovie source and play it back with ffplay: |
ffplay −f lavfi "amovie=test.wav"
|
• |
Read an audio stream and a video stream and play it back with ffplay: |
ffplay −f lavfi "movie=test.avi[out0];amovie=test.wav[out1]"
libdc1394
IIDC1394 input device, based on libdc1394 and
libraw1394.
openal
The OpenAL input device provides audio capture on all
systems with a working OpenAL 1.1 implementation.
To enable this input device during configuration, you need OpenAL headers and libraries installed on your system, and need to configure FFmpeg with "−−enable−openal".
OpenAL headers and libraries should be provided as part of your OpenAL implementation, or as an additional download (an SDK ). Depending on your installation you may need to specify additional flags via the "−−extra−cflags" and "−−extra−ldflags" for allowing the build system to locate the OpenAL headers and libraries.
An incomplete
list of OpenAL implementations follows:
Creative
The official Windows implementation, providing hardware acceleration with supported devices and software fallback. See <http://openal.org/>.
OpenAL Soft
Portable, open source ( LGPL ) software implementation. Includes backends for the most common sound APIs on the Windows, Linux, Solaris, and BSD operating systems. See <http://kcat.strangesoft.net/openal.html>.
Apple
OpenAL is part of Core Audio, the official Mac OS X Audio interface. See <http://developer.apple.com/technologies/mac/audio−and−video.html>
This device allows to capture from an audio input device handled through OpenAL.
You need to specify the name of the device to capture in the provided filename. If the empty string is provided, the device will automatically select the default device. You can get the list of the supported devices by using the option list_devices.
Options
channels
Set the number of channels in the captured audio. Only the values 1 (monaural) and 2 (stereo) are currently supported. Defaults to 2.
sample_size
Set the sample size (in bits) of the captured audio. Only the values 8 and 16 are currently supported. Defaults to 16.
sample_rate
Set the sample rate (in Hz) of the captured audio. Defaults to 44.1k.
list_devices
If set to true, print a list of devices and exit. Defaults to false.
Examples
Print the list of OpenAL supported devices and exit:
$ ffmpeg −list_devices true −f openal −i dummy out.ogg
Capture from the OpenAL device DR−BT101 via PulseAudio:
$ ffmpeg −f openal −i 'DR−BT101 via PulseAudio' out.ogg
Capture from the default device (note the empty string ’’ as filename):
$ ffmpeg −f openal −i '' out.ogg
Capture from two devices simultaneously, writing to two different files, within the same ffmpeg command:
$ ffmpeg −f openal −i 'DR−BT101 via PulseAudio' out1.ogg −f openal −i 'ALSA Default' out2.ogg
Note: not all OpenAL implementations support multiple simultaneous capture − try the latest OpenAL Soft if the above does not work.
oss
Open Sound System input device.
The filename to provide to the input device is the device node representing the OSS input device, and is usually set to /dev/dsp.
For example to grab from /dev/dsp using ffmpeg use the command:
ffmpeg −f oss −i /dev/dsp /tmp/oss.wav
For more information about OSS see: <http://manuals.opensound.com/usersguide/dsp.html>
pulse
pulseaudio input device.
To enable this input device during configuration you need libpulse-simple installed in your system.
The filename to provide to the input device is a source device or the string "default"
To list the pulse source devices and their properties you can invoke the command pactl list sources.
ffmpeg −f pulse −i default /tmp/pulse.wav
server AVOption
The syntax is:
−server <server name>
Connects to a specific server.
name AVOption
The syntax is:
−name <application name>
Specify the application name pulse will use when showing active clients, by default it is the LIBAVFORMAT_IDENT string
stream_name AVOption
The syntax is:
−stream_name <stream name>
Specify the stream name pulse will use when showing active streams, by default it is "record"
sample_rate AVOption
The syntax is:
−sample_rate <samplerate>
Specify the samplerate in Hz, by default 48kHz is used.
channels AVOption
The syntax is:
−channels <N>
Specify the channels in use, by default 2 (stereo) is set.
frame_size AVOption
The syntax is:
−frame_size <bytes>
Specify the number of byte per frame, by default it is set to 1024.
fragment_size AVOption
The syntax is:
−fragment_size <bytes>
Specify the minimal buffering fragment in pulseaudio, it will affect the audio latency. By default it is unset.
sndio
sndio input device.
To enable this input device during configuration you need libsndio installed on your system.
The filename to provide to the input device is the device node representing the sndio input device, and is usually set to /dev/audio0.
For example to grab from /dev/audio0 using ffmpeg use the command:
ffmpeg −f sndio −i /dev/audio0 /tmp/oss.wav
video4linux2
Video4Linux2 input video device.
The name of the device to grab is a file device node, usually Linux systems tend to automatically create such nodes when the device (e.g. an USB webcam) is plugged into the system, and has a name of the kind /dev/videoN, where N is a number associated to the device.
Video4Linux2 devices usually support a limited set of widthxheight sizes and framerates. You can check which are supported using −list_formats all for Video4Linux2 devices.
Some usage examples of the video4linux2 devices with ffmpeg and ffplay:
The time base for the timestamps is 1 microsecond. Depending on the kernel version and configuration, the timestamps may be derived from the real time clock (origin at the Unix Epoch) or the monotonic clock (origin usually at boot time, unaffected by NTP or manual changes to the clock). The −timestamps abs or −ts abs option can be used to force conversion into the real time clock.
Note that if FFmpeg is build with v4l−utils support ("−−enable−libv4l2" option), it will always be used.
# Grab and show the input of a video4linux2 device.
ffplay −f video4linux2 −framerate 30 −video_size hd720 /dev/video0
# Grab and record the input of a video4linux2 device, leave the
framerate and size as previously set.
ffmpeg −f video4linux2 −input_format mjpeg −i /dev/video0 out.mpeg
"v4l" and "v4l2" can be used as aliases for the respective "video4linux" and "video4linux2".
vfwcap
VfW (Video for Windows) capture input device.
The filename passed as input is the capture driver number, ranging from 0 to 9. You may use "list" as filename to print a list of drivers. Any other filename will be interpreted as device number 0.
x11grab
X11 video input device.
This device allows to capture a region of an X11 display.
The filename passed as input has the syntax:
[<hostname>]:<display_number>.<screen_number>[+<x_offset>,<y_offset>]
hostname:display_number.screen_number specifies the X11 display name of the screen to grab from. hostname can be omitted, and defaults to "localhost". The environment variable DISPLAY contains the default display name.
x_offset and y_offset specify the offsets of the grabbed area with respect to the top-left border of the X11 screen. They default to 0.
Check the X11 documentation (e.g. man X) for more detailed information.
Use the dpyinfo program for getting basic information about the properties of your X11 display (e.g. grep for "name" or "dimensions").
For example to grab from :0.0 using ffmpeg:
ffmpeg −f x11grab −r 25 −s cif −i :0.0 out.mpg
Grab at position "10,20":
ffmpeg −f x11grab −r 25 −s cif −i :0.0+10,20 out.mpg
Options
draw_mouse
Specify whether to draw the mouse pointer. A value of 0 specify not to draw the pointer. Default value is 1.
follow_mouse
Make the grabbed area follow the mouse. The argument can be "centered" or a number of pixels PIXELS .
When it is specified with "centered", the grabbing region follows the mouse pointer and keeps the pointer at the center of region; otherwise, the region follows only when the mouse pointer reaches within PIXELS (greater than zero) to the edge of region.
For example:
ffmpeg −f x11grab −follow_mouse centered −r 25 −s cif −i :0.0 out.mpg
To follow only when the mouse pointer reaches within 100 pixels to edge:
ffmpeg −f x11grab −follow_mouse 100 −r 25 −s cif −i :0.0 out.mpg
framerate
Set the grabbing frame rate. Default value is "ntsc", corresponding to a framerate of "30000/1001".
show_region
Show grabbed region on screen.
If show_region is specified with 1, then the grabbing region will be indicated on screen. With this option, it is easy to know what is being grabbed if only a portion of the screen is grabbed.
For example:
ffmpeg −f x11grab −show_region 1 −r 25 −s cif −i :0.0+10,20 out.mpg
With follow_mouse:
ffmpeg −f x11grab −follow_mouse centered −show_region 1 −r 25 −s cif −i :0.0 out.mpg
video_size
Set the video frame size. Default value is "vga".
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