ffmpeg Docs
From: https://ffmpeg.org/ffmpeg.html
- Synopsis
- Description
- Detailed description
- Filtering
- Simple filtergraphs
- Complex filtergraphs
- Stream copy
- Stream selection
- Description
- Automatic stream selection
- Manual stream selection
- Complex filtergraphs
- Stream handling
- Examples
- Options
- Stream specifiers
- Generic options
- AVOptions
- Main options
- Video Options
- Advanced Video options
- Audio Options
- Advanced Audio options
- Subtitle options
- Advanced Subtitle options
- Advanced options
- Preset files
- ffpreset files
- avpreset files
- vstats file format
- Examples
- Video and Audio grabbing
- X11 grabbing
- Video and Audio file format conversion
- See Also
- Authors
ffmpeg Documentation
1 Synopsis
ffmpeg [global_options] {[input_file_options] -i input_url} ...
{[output_file_options] output_url} ...
2 Description
ffmpeg is a universal media converter. It can read a wide variety of inputs
- including live grabbing/recording devices - filter, and transcode them
into a plethora of output formats.
ffmpeg reads from an arbitrary number of input "files" (which can be regular
files, pipes, network streams, grabbing devices, etc.), specified by the -i
option, and writes to an arbitrary number of output "files", which are
specified by a plain output url. Anything found on the command line which
cannot be interpreted as an option is considered to be an output url.
Each input or output url can, in principle, contain any number of streams of
different types (video/audio/subtitle/attachment/data). The allowed number
and/or types of streams may be limited by the container format. Selecting
which streams from which inputs will go into which output is either done
automatically or with the -map option (see the Stream selection chapter).
To refer to input files in options, you must use their indices (0-based).
E.g. the first input file is 0, the second is 1, etc. Similarly, streams
within a file are referred to by their indices. E.g. 2:3 refers to the
fourth stream in the third input file. Also see the Stream specifiers chapter.
As a general rule, options are applied to the next specified file.
Therefore, order is important, and you can have the same option on the
command line multiple times. Each occurrence is then applied to the next
input or output file. Exceptions from this rule are the global options (e.g.
verbosity level), which should be specified first.
Do not mix input and output files – first specify all input files, then
all output files. Also do not mix options which belong to different files.
All options apply ONLY to the next input or output file and are reset between files.
Some simple examples follow.
- Convert an input media file to a different format, by re-encoding media
streams:
ffmpeg -i input.avi output.mp4
- Set the video bitrate of the output file to 64 kbit/s:
ffmpeg -i input.avi -b:v 64k -bufsize 64k output.mp4
- Force the frame rate of the output file to 24 fps:
ffmpeg -i input.avi -r 24 output.mp4
- Force the frame rate of the input file (valid for raw formats only) to 1
fps and the frame rate of the output file to 24 fps:
ffmpeg -r 1 -i input.m2v -r 24 output.mp4
The format option may be needed for raw input files.
3 Detailed description
The transcoding process in ffmpeg for each output can be described by the
following diagram:
_______ ______________
| | | |
| input | demuxer | encoded data | decoder
| file | ---------> | packets | -----+
|_______| |______________| |
v
_________
| |
| decoded |
| frames |
|_________|
________ ______________ |
| | | | |
| output | <-------- | encoded data | <----+
| file | muxer | packets | encoder
|________| |______________|
ffmpeg calls the libavformat library (containing demuxers) to read input
files and get packets containing encoded data from them. When there are
multiple input files, ffmpeg tries to keep them synchronized by tracking
lowest timestamp on any active input stream.
Encoded packets are then passed to the decoder (unless streamcopy is selected
for the stream, see further for a description). The decoder produces
uncompressed frames (raw video/PCM audio/...) which can be processed further by
filtering (see next section). After filtering, the frames are passed to the
encoder, which encodes them and outputs encoded packets. Finally those are
passed to the muxer, which writes the encoded packets to the output file.
3.1-Filtering
Before encoding, ffmpeg can process raw audio and video frames using filters
from the libavfilter library. Several chained filters form a filter graph.
ffmpeg distinguishes between two types of filtergraphs: simple and complex.
3.1.1 Simple filtergraphs
Simple filtergraphs are those that have exactly one input and output, both of
the same type. In the above diagram they can be represented by simply inserting
an additional step between decoding and encoding:
_________ ______________
| | | |
| decoded | | encoded data |
| frames |\ _ | packets |
|_________| \ /||______________|
\ __________ /
simple _\|| | / encoder
filtergraph | filtered |/
| frames |
|__________|
Simple filtergraphs are configured with the per-stream -filter option (with -vf
and -af aliases for video and audio respectively). A simple filtergraph for
video can look for example like this:
_______ _____________ _______ ________
| | | | | | | |
| input | ---> | deinterlace | ---> | scale | ---> | output |
|_______| |_____________| |_______| |________|
Note that some filters change frame properties but not frame contents. E.g.
the fps filter in the example above changes number of frames, but does not
touch the frame contents. Another example is the setpts filter, which only
sets timestamps and otherwise passes the frames unchanged.
3.1.2 Complex filtergraphs
Complex filtergraphs are those which cannot be described as simply a linear
processing chain applied to one stream. This is the case, for example, when
the graph has more than one input and/or output, or when output stream type
is different from input. They can be represented with the following
diagram:
_________
| |
| input 0 |\ __________
|_________| \ | |
\ _________ /| output 0 |
\ | | / |__________|
_________ \| complex | /
| | | |/
| input 1 |---->| filter |\
|_________| | | \ __________
/| graph | \ | |
/ | | \| output 1 |
_________ / |_________| |__________|
| | /
| input 2 |/
|_________|
Complex filtergraphs are configured with the -filter_complex option. Note
that this option is global, since a complex filtergraph, by its nature,
cannot be unambiguously associated with a single stream or file.
The -lavfi option is equivalent to -filter_complex.
A trivial example of a complex filtergraph is the overlay filter, which has
two video inputs and one video output, containing one video overlaid on top
of the other. Its audio counterpart is the amix filter.
3.2 Stream copy
Stream copy is a mode selected by supplying the copy parameter to the -codec
option. It makes ffmpeg omit the decoding and encoding step for the
specified stream, so it does only demuxing and muxing. It is useful for
changing the container format or modifying container-level metadata. The
diagram above will, in this case, simplify to this:
_______ ______________ ________
| | | | | |
| input | demuxer | encoded data | muxer | output |
| file | ---------> | packets | -------> | file |
|_______| |______________| |________|
Since there is no decoding or encoding, it is very fast and there is no
quality loss. However, it might not work in some cases because of many
factors. Applying filters is obviously also impossible, since filters work
on uncompressed data.
4 Stream selection
ffmpeg provides the -map
option for manual control of stream selection in each output file. Users can
skip -map and let ffmpeg perform automaticstream selection as described below.
The -vn / -an / -sn / -dn options can be used to skip inclusion of video,
audio, subtitle and data streams respectively, whether manually mapped or
automatically selected, except for those streams which are outputs of complex
filtergraphs.
4.1 Description
The sub-sections that follow describe the various rules that are involved in
stream selection. The examples that follow next show how these rules are
applied in practice.
While every effort is made to accurately reflect the behavior of the
program, FFmpeg is under continuous development and the code may have
changed since the time of this writing.
4.1.1 Automatic stream selection
In the absence of any map options for a particular output file, ffmpeg
inspects the output format to check which type of streams can be included
in it, viz. video, audio and/or subtitles. For each acceptable stream type,
ffmpeg will pick one stream, when available, from among all the inputs.
It will select that stream based upon the following criteria:
- for video, it is the stream with the highest resolution,
- for audio, it is the stream with the most channels,
- for subtitles, it is the first subtitle stream found but there’s a
caveat. The output format’s default subtitle encoder can be either text-based
or image-based, and only a subtitle stream of the same type will be chosen.
In the case where several streams of the same type rate equally, the stream
with the lowest index is chosen.
Data or attachment streams are not automatically selected and can only be
included using -map.
4.1.2 Manual stream selection
When -map is used, only user-mapped streams are included in that output
file, with one possible exception for filtergraph outputs described below.
4.1.3 Complex filtergraphs
If there are any complex filtergraph output streams with unlabeled pads,
they will be added to the first output file. This will lead to a fatal error
if the stream type is not supported by the output format. In the absence of
the map option, the inclusion of these streams leads to the automatic stream
selection of their types being skipped. If map options are present, these
filtergraph streams are included in addition to the mapped streams.
Complex filtergraph output streams with labeled pads must be mapped once and
exactly once.
4.1.4 Stream handling
Stream handling is independent of stream selection, with an exception for
subtitles described below. Stream handling is set via the -codec option
addressed to streams within a specific output file. In particular, codec
options are applied by ffmpeg after the stream selection process and thus do
not influence the latter. If no -codec option is specified for a stream
type, ffmpeg will select the default encoder registered by the output file
muxer.
An exception exists for subtitles. If a subtitle encoder is specified for an
output file, the first subtitle stream found of any type, text or image,
will be included. ffmpeg does not validate if the specified encoder can
convert the selected stream or if the converted stream is acceptable within
the output format. This applies generally as well: when the user sets an
encoder manually, the stream selection process cannot check if the encoded
stream can be muxed into the output file. If it cannot, ffmpeg will abort
and all output files will fail to be processed.
4.2 Examples
The following examples illustrate the behavior, quirks and limitations of
ffmpeg’s stream selection methods.
They assume the following three input files.
input file 'A.avi'
stream 0: video 640x360
stream 1: audio 2 channels
input file 'B.mp4'
stream 0: video 1920x1080
stream 1: audio 2 channels
stream 2: subtitles (text)
stream 3: audio 5.1 channels
stream 4: subtitles (text)
input file 'C.mkv'
stream 0: video 1280x720
stream 1: audio 2 channels
stream 2: subtitles (image)
Example: automatic stream selection
ffmpeg -i A.avi -i B.mp4 out1.mkv out2.wav -map 1:a -c:a copy out3.mov
There are three output files specified, and for the first two, no -map
options are set, so ffmpeg will select streams for these two files
automatically.
out1.mkv is a Matroska container file and accepts video, audio and subtitle
streams, so ffmpeg will try to select one of each type. For video, it will
select stream 0 from B.mp4, which has the highest resolution among all the
input video streams. For audio, it will select stream 3 from B.mp4, since it
has the greatest number of channels. For subtitles, it will select stream 2
from B.mp4, which is the first subtitle stream from among A.avi and B.mp4.
out2.wav accepts only audio streams, so only stream 3 from B.mp4 is selected.
For out3.mov, since a -map option is set, no automatic stream selection will
occur. The -map 1:a option will select all audio streams from the second
input B.mp4. No other streams will be included in this output file.
For the first two outputs, all included streams will be transcoded. The
encoders chosen will be the default ones registered by each output format,
which may not match the codec of the selected input streams.
For the third output, codec option for audio streams has been set to copy,
so no decoding-filtering-encoding operations will occur, or can occur.
Packets of selected streams shall be conveyed from the input file and muxed
within the output file.
Example: automatic subtitles selection
ffmpeg -i C.mkv out1.mkv -c:s dvdsub -an out2.mkv
Although out1.mkv is a Matroska container file which accepts subtitle
streams, only a video and audio stream shall be selected. The subtitle
stream of C.mkv is image-based and the default subtitle encoder of the
Matroska muxer is text-based, so a transcode operation for the subtitles is
expected to fail and hence the stream isn’t selected. However, in
out2.mkv, a subtitle encoder is specified in the command and so, the
subtitle stream is selected, in addition to the video stream. The presence
of -an disables audio stream selection for out2.mkv.
Example: unlabeled filtergraph outputs
ffmpeg -i A.avi -i C.mkv -i B.mp4 -filter_complex "overlay" out1.mp4
out2.srt
A filtergraph is setup here using the -filter_complex option and consists of
a single video filter. The overlay filter requires exactly two video inputs,
but none are specified, so the first two available video streams are used,
those of A.avi and C.mkv. The output pad of the filter has no label and so
is sent to the first output file out1.mp4. Due to this, automatic selection
of the video stream is skipped, which would have selected the stream in
B.mp4. The audio stream with most channels viz. stream 3 in B.mp4, is chosen
automatically. No subtitle stream is chosen however, since the MP4 format
has no default subtitle encoder registered, and the user hasn’t specified
a subtitle encoder.
The 2nd output file, out2.srt, only accepts text-based subtitle streams. So,
even though the first subtitle stream available belongs to C.mkv, it is
image-based and hence skipped. The selected stream, stream 2 in B.mp4, is
the first text-based subtitle stream.
Example: labeled filtergraph outputs
ffmpeg -i A.avi -i B.mp4 -i C.mkv -filter_complex "[
1:v]hue=s=0[outv];overlay;aresample" \
-map '[outv]' -an out1.mp4 \
out2.mkv \
-map '[outv]' -map 1:a:0 out3.mkv
The above command will fail, as the output pad labelled [outv] has been
mapped twice. None of the output files shall be processed.
ffmpeg -i A.avi -i B.mp4 -i C.mkv -filter_complex "[
1:v]hue=s=0[outv];overlay;aresample" \
-an out1.mp4 \
out2.mkv \
-map 1:a:0 out3.mkv
This command above will also fail as the hue filter output has a label,
[outv], and hasn’t been mapped anywhere.
The command should be modified as follows,
ffmpeg -i A.avi -i B.mp4 -i C.mkv -filter_complex "[
1:v]hue=s=0,split=2[outv1][outv2];overlay;aresample" \
-map '[outv1]' -an out1.mp4 \
out2.mkv \
-map '[outv2]' -map 1:a:0 out3.mkv
The video stream from B.mp4 is sent to the hue filter, whose output is
cloned once using the split filter, and both outputs labelled. Then a copy
each is mapped to the first and third output files.
The overlay filter, requiring two video inputs, uses the first two unused
video streams. Those are the streams from A.avi and C.mkv. The overlay
output isn’t labelled, so it is sent to the first output file out1.mp4,
regardless of the presence of the -map option.
The aresample filter is sent the first unused audio stream, that of A.avi.
Since this filter output is also unlabelled, it too is mapped to the first
output file. The presence of -an only suppresses automatic or manual stream
selection of audio streams, not outputs sent from filtergraphs. Both these
mapped streams shall be ordered before the mapped stream in out1.mp4.
The video, audio and subtitle streams mapped to out2.mkv are entirely
determined by automatic stream selection.
out3.mkv consists of the cloned video output from the hue filter and the
first audio stream from B.mp4.
5 Options
All the numerical options, if not specified otherwise, accept a string
representing a number as input, which may be followed by one of the SI unit
prefixes, for example: ’K’, ’M’, or ’G’.
If ’i’ is appended to the SI unit prefix, the complete prefix will be
interpreted as a unit prefix for binary multiples, which are based on powers
of 1024 instead of powers of 1000. Appending ’B’ to the SI unit prefix
multiplies the value by 8. This allows using, for example: ’KB’,
’MiB’, ’G’ and ’B’ as number suffixes.
Options which do not take arguments are boolean options, and set the
corresponding value to true. They can be set to false by prefixing the
option name with "no". For example using "-nofoo" will set the boolean
option with name "foo" to false.
5.1 Stream specifiers
Some options are applied per-stream, e.g. bitrate or codec. Stream
specifiers are used to precisely specify which stream(s) a given option
belongs 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 contains the 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, so that the option is 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. If stream_index is used as an
additional stream specifier (see below), then it selects stream number
stream_index from the matching streams. Stream numbering is based on the
order of the streams as detected by libavformat except when a program ID is
also specified. In this case it is based on the ordering of the streams in
the program.
stream_type[:additional_stream_specifier]
stream_type is one of following: ’v’ or ’V’ for video, ’a’
for audio, ’s’ for subtitle, ’d’ for data, and ’t’ for
attachments. ’v’ matches all video streams, ’V’ only matches video
streams which are not attached pictures, video thumbnails or cover arts. If
additional_stream_specifier is used, then it matches streams which both have
this type and match the additional_stream_specifier. Otherwise, it matches
all streams of the specified type.
p:program_id[:additional_stream_specifier]
Matches streams which are in the program with the id program_id. If
additional_stream_specifier is used, then it matches streams which both are
part of the program and match the additional_stream_specifier.
#stream_id or i:stream_id
Match the stream by stream id (e.g. PID in MPEG-TS container).
m:key[:value]
Matches streams with the metadata tag key having the specified value. If
value is not given, matches streams that contain the given tag with any value.
u
Matches streams with usable configuration, the codec must be defined and
the essential information such as video dimension or audio sample rate must
be present.
Note that in ffmpeg, matching by metadata will only work properly for
input files.
5.2 Generic options
These options are shared amongst the ff* tools.
-L
Show license.
-h, -?, -help, --help [arg]
Show help. An optional parameter may be specified to print help about a
specific item. If no argument is specified, only basic (non advanced) tool
options are shown.
Possible values of arg are:
long
Print advanced tool options in addition to the basic tool options.
full
Print complete list of options, including shared and private options
for encoders, decoders, demuxers, muxers, filters, etc.
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.
filter=filter_name
Print detailed information about the filter named filter_name. Use
the -filters option to get a list of all filters.
bsf=bitstream_filter_name
Print detailed information about the bitstream filter named
bitstream_filter_name. Use the -bsfs option to get a list of all
bitstream filters.
protocol=protocol_name
Print detailed information about the protocol named protocol_name.
Use the -protocols option to get a list of all protocols.
-version
Show version.
-buildconf
Show the build configuration, one option per line.
-formats
Show available formats (including devices).
-demuxers
Show available demuxers.
-muxers
Show available muxers.
-devices
Show available devices.
-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.
-dispositions
Show stream dispositions.
-colors
Show recognized color names.
-sources device[,opt1=val1[,opt2=val2]...]
Show autodetected sources of the input device. Some devices may provide
system-dependent source names that cannot be autodetected. The returned list
cannot be assumed to be always complete.
ffmpeg -sources pulse,server=192.168.0.4
-sinks device[,opt1=val1[,opt2=val2]...]
Show autodetected sinks of the output device. Some devices may provide
system-dependent sink names that cannot be autodetected. The returned list
cannot be assumed to be always complete.
ffmpeg -sinks pulse,server=192.168.0.4
-loglevel [flags+]loglevel | -v [flags+]loglevel
Set logging level and flags used by the library.
The optional flags prefix can consist of the following values:
‘repeat’
Indicates that repeated log output should not be compressed to the
first line and the "Last message repeated n times" line will be omitted.
‘level’
Indicates that log output should add a [level] prefix to each
message line. This can be used as an alternative to log coloring, e.g. when
dumping the log to file.
Flags can also be used alone by adding a ’+’/’-’ prefix to set/reset a
single flag without affecting other flags or changing loglevel. When
setting both flags and loglevel, a ’+’ separator is expected between the
last flags value and before loglevel.
loglevel is a string or a number containing one of the following values:
‘quiet, -8’
Show nothing at all; be silent.
‘panic, 0
Only show fatal errors which could lead the process to crash, such as an
assertion failure. This is not currently used for anything.
‘fatal, 8’
Only show fatal errors. These are errors after which the process absolutely
cannot continue.
‘error, 16’
Show all errors, including ones which can be recovered from.
‘warning, 24’
Show all warnings and errors. Any message related to possibly incorrect or
unexpected events will be shown.
‘info, 32’
Show informative messages during processing. This is in addition to warnings
and errors. This is the default value.
‘verbose, 40’
Same as info, except more verbose.
‘debug, 48’
Show everything, including debugging information.
‘trace, 56’
For example to enable repeated log output, add the level prefix, and set
loglevel to verbose:
ffmpeg -loglevel repeat+level+verbose -i input output
Another example that enables repeated log output without affecting
current state of level prefix flag or loglevel:
ffmpeg [...] -loglevel +repeat
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 can be
forced setting the environment variable AV_LOG_FORCE_COLOR.
-report
Dump full command line and log 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 debug.
Setting the environment variable FFREPORT to any value has the same
effect. If the value is a ’:’-separated key=value sequence, these
options will affect the report; option values must be escaped if they
contain special characters or the options delimiter ’:’ (see the
“Quoting and escaping” section in the ffmpeg-utils manual).
The following options are recognized:
file
set the file name to use for the report; %p is expanded to the name of the
program, %t is expanded to a timestamp, %% is expanded to a plain %
level
set the log verbosity level using a numerical value (see -loglevel).
For example, to output a report to a file named ffreport.log using a log
level of 32 (alias for log level info):
FFREPORT=file=ffreport.log:level=32 ffmpeg -i input output
Errors in parsing the environment variable are not fatal, and will not appear
in the report.
-hide_banner
Suppress printing banner.
All FFmpeg tools will normally show a copyright notice, build options and
library versions. This option can be used to suppress printing this information.
-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 ...
Possible flags for this option are:
‘x86’
‘mmx’
‘mmxext’
‘sse’
‘sse2’
‘sse2slow’
‘sse3’
‘sse3slow’
‘ssse3’
‘atom’
‘sse4.1’
‘sse4.2’
‘avx’
‘avx2’
‘xop’
‘fma3’
‘fma4’
‘3dnow’
‘3dnowext’
‘bmi1’
‘bmi2’
‘cmov’
‘ARM’
‘armv5te’
‘armv6’
‘armv6t2’
‘vfp’
‘vfpv3’
‘neon’
‘setend’
‘AArch64’
‘armv8’
‘vfp’
‘neon’
‘PowerPC’
‘altivec’
‘Specific Processors’
‘pentium2’
‘pentium3’
‘pentium4’
‘k6’
‘k62’
‘athlon’
‘athlonxp’
‘k8’
-cpucount count (global)
Override detection of CPU count. This option is intended for testing. Do not
use it unless you know what you’re doing.
ffmpeg -cpucount 2
-max_alloc bytes
Set the maximum size limit for allocating a block on the heap by
ffmpeg’s family of malloc functions. Exercise extreme caution when using
this option. Don’t use if you do not understand the full consequence of
doing so. Default is INT_MAX.
5.3 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 per-stream, and thus a stream specifier should be attached
to them:
ffmpeg -i multichannel.mxf -map 0:v:0 -map 0:a:0 -map 0:a:0 -c:a:0 ac3
-b:a:0 640k -ac:a:1 2 -c:a:1 aac -b:2 128k out.mp4
In the above example, a multichannel audio stream is mapped twice for
output. The first instance is encoded with codec ac3 and bitrate 640k. The
second instance is downmixed to 2 channels and encoded with codec aac. A
bitrate of 128k is specified for it using absolute index of the output
stream.
Note: the -nooption syntax cannot be used for boolean AVOptions, use -option
0/-option 1.
Note: the 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.
5.4 Main options
-f fmt (input/output)
Force input or output file format. The format is normally auto detected for
input files and guessed from the file extension for output files, so this
option is not needed in most cases.
-i url (input)
input file url
-y (global)
Overwrite output files without asking.
-n (global)
Do not overwrite output files, and exit immediately if a specified output
file already exists.
-stream_loop number (input)
Set number of times input stream shall be looped. Loop 0 means no loop,
loop -1 means infinite loop.
-recast_media (global)
Allow forcing a decoder of a different media type than the one detected or
designated by the demuxer. Useful for decoding media data muxed as data streams.
-c[:stream_specifier] codec (input/output,per-stream)
-codec[:stream_specifier] codec (input/output,per-stream)
Select an encoder (when used before an output file) or a decoder (when used
before an input file) for one or more streams. codec is the name of a
decoder/encoder or a special value copy (output only) to indicate that the
stream is not to be re-encoded.
For example
ffmpeg -i INPUT -map 0 -c:v libx264 -c:a copy OUTPUT
encodes all video streams with libx264 and copies all audio streams.
For each stream, the last matching c option is applied, so
ffmpeg -i INPUT -map 0 -c copy -c:v:1 libx264 -c:a:137 libvorbis
OUTPUT
will copy all the streams except the second video, which will be encoded
with libx264, and the 138th audio, which will be encoded with libvorbis.
-t duration (input/output)
When used as an input option (before -i), limit the duration of data read
from the input file.
When used as an output option (before an output url), stop writing the
output after its duration reaches duration.
duration must be a time duration specification,
see (ffmpeg-utils)the Timeduration section in the ffmpeg-utils(1)
manual.
-to and -t are mutually exclusive and -t has priority.
-to position (input/output)
Stop writing the output or reading the input at position. position must
be a time duration specification, see (ffmpeg-utils)the Time duration
section in the ffmpeg-utils(1) manual.
-to and -t are mutually exclusive and -t has priority.
-fs limit_size (output)
Set the file size limit, expressed in bytes. No further chunk of bytes
is written after the limit is exceeded. The size of the output file is
slightly more than the requested file size.
-ss position (input/output)
When used as an input option (before -i), seeks in this input file to
position. Note that in most formats it is not possible to seek exactly, so
ffmpeg will seek to the closest seek point before position. When transcoding
and -accurate_seek is enabled (the default), this extra segment between the
seek point and position will be decoded and discarded. When doing stream
copy or when -noaccurate_seek is used, it will be preserved.
When used as an output option (before an output url), decodes but
discards input until the timestamps reach position.
position must be a time duration specification, see (ffmpeg-utils)the
Time duration section in the ffmpeg-utils(1) manual.
-sseof position (input)
Like the -ss option but relative to the "end of file". That is negative
values are earlier in the file, 0 is at EOF.
-isync input_index (input)
Assign an input as a sync source.
This will take the difference between the start times of the target and
reference inputs and offset the timestamps of the target file by that
difference. The source timestamps of the two inputs should derive from the
same clock source for expected results. If copyts is set then start_at_zero
must also be set. If either of the inputs has no starting timestamp then no
sync adjustment is made.
Acceptable values are those that refer to a valid ffmpeg input index. If
the sync reference is the target index itself or -1, then no adjustment is
made to target timestamps. A sync reference may not itself be synced to any
other input.
Default value is -1.
-itsoffset offset (input)
Set the input time offset.
offset must be a time duration specification, see (ffmpeg-utils)the Time
duration section in the ffmpeg-utils(1) manual.
The offset is added to the timestamps of the input files. Specifying a
positive offset means that the corresponding streams are delayed by the time
duration specified in offset.
-itsscale scale (input,per-stream)
Rescale input timestamps. scale should be a floating point number.
-timestamp date (output)
Set the recording timestamp in the container.
date must be a date specification, see (ffmpeg-utils)the Date section in
the ffmpeg-utils(1) manual.
-metadata[:metadata_specifier] key=value (output,per-metadata)
Set a metadata key/value pair.
An optional metadata_specifier may be given to set metadata on streams,
chapters or programs. See -map_metadata documentation for details.
This option overrides metadata set with -map_metadata. It is also possible
to delete metadata by using an empty value.
For example, for setting the title in the output file:
ffmpeg -i in.avi -metadata title="my title" out.flv
To set the language of the first audio stream:
ffmpeg -i INPUT -metadata:s:a:0 language=eng OUTPUT
-disposition[:stream_specifier] value (output,per-stream)
Sets the disposition for a stream.
By default, the disposition is copied from the input stream, unless the
output stream this option applies to is fed by a complex filtergraph - in
that case the disposition is unset by default.
value is a sequence of items separated by ’+’ or ’-’. The first item may
also be prefixed with ’+’ or ’-’, in which case this option modifies the
default value. Otherwise (the first item is not prefixed) this options
overrides the default value. A ’+’ prefix adds the given disposition, ’-’
removes it. It is also possible to clear the disposition by setting it to 0.
If no -disposition options were specified for an output file, ffmpeg will
automatically set the ’default’ disposition on the first stream of each type
, when there are multiple streams of this type in the output file and no
stream of that type is already marked as default.
The -dispositions option lists the known dispositions.
For example, to make the second audio stream the default stream:
ffmpeg -i in.mkv -c copy -disposition:a:1 default out.mkv
To make the second subtitle stream the default stream and remove the
default disposition from the first subtitle stream:
ffmpeg -i in.mkv -c copy -disposition:s:0 0 -disposition:s:1 default out.mkv
To add an embedded cover/thumbnail:
ffmpeg -i in.mp4 -i IMAGE -map 0 -map 1 -c copy -c:v:1 png
-disposition:v:1 attached_pic out.mp4
Not all muxers support embedded thumbnails, and those who do, only
support a few formats, like JPEG or PNG.
-program [title=title:][program_num=program_num:]st=stream[:st=stream...]
(output)
Creates a program with the specified title, program_num and adds the
specified stream(s) to it.
-target type (output)
Specify target file type (vcd, svcd, dvd, dv, dv50). type may be prefixed
with pal-, ntsc- or film- to use the corresponding standard. All the format
options (bitrate, codecs, buffer sizes) are then set automatically. You can
just type:
ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
Nevertheless you can specify additional options as long as you know they do
not conflict with the standard, as in:
ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
The parameters set for each target are as follows.
VCD
pal:
-f vcd -muxrate 1411200 -muxpreload 0.44 -packetsize 2324
-s 352x288 -r 25
-codec:v mpeg1video -g 15 -b:v 1150k -maxrate:v 1150k -minrate:v 1150k
-bufsize:v 327680
-ar 44100 -ac 2
-codec:a mp2 -b:a 224k
ntsc:
-f vcd -muxrate 1411200 -muxpreload 0.44 -packetsize 2324
-s 352x240 -r 30000/1001
-codec:v mpeg1video -g 18 -b:v 1150k -maxrate:v 1150k -minrate:v 1150k
-bufsize:v 327680
-ar 44100 -ac 2
-codec:a mp2 -b:a 224k
film:
-f vcd -muxrate 1411200 -muxpreload 0.44 -packetsize 2324
-s 352x240 -r 24000/1001
-codec:v mpeg1video -g 18 -b:v 1150k -maxrate:v 1150k -minrate:v 1150k
-bufsize:v 327680
-ar 44100 -ac 2
-codec:a mp2 -b:a 224k
SVCD
pal:
-f svcd -packetsize 2324
-s 480x576 -pix_fmt yuv420p -r 25
-codec:v mpeg2video -g 15 -b:v 2040k -maxrate:v 2516k -minrate:v 0
-bufsize:v 1835008 -scan_offset 1
-ar 44100
-codec:a mp2 -b:a 224k
ntsc:
-f svcd -packetsize 2324
-s 480x480 -pix_fmt yuv420p -r 30000/1001
-codec:v mpeg2video -g 18 -b:v 2040k -maxrate:v 2516k -minrate:v 0
-bufsize:v 1835008 -scan_offset 1
-ar 44100
-codec:a mp2 -b:a 224k
film:
-f svcd -packetsize 2324
-s 480x480 -pix_fmt yuv420p -r 24000/1001
-codec:v mpeg2video -g 18 -b:v 2040k -maxrate:v 2516k -minrate:v 0
-bufsize:v 1835008 -scan_offset 1
-ar 44100
-codec:a mp2 -b:a 224k
DVD
pal:
-f dvd -muxrate 10080k -packetsize 2048
-s 720x576 -pix_fmt yuv420p -r 25
-codec:v mpeg2video -g 15 -b:v 6000k -maxrate:v 9000k -minrate:v 0
-bufsize:v 1835008
-ar 48000
-codec:a ac3 -b:a 448k
ntsc:
-f dvd -muxrate 10080k -packetsize 2048
-s 720x480 -pix_fmt yuv420p -r 30000/1001
-codec:v mpeg2video -g 18 -b:v 6000k -maxrate:v 9000k -minrate:v 0
-bufsize:v 1835008
-ar 48000
-codec:a ac3 -b:a 448k
film:
-f dvd -muxrate 10080k -packetsize 2048
-s 720x480 -pix_fmt yuv420p -r 24000/1001
-codec:v mpeg2video -g 18 -b:v 6000k -maxrate:v 9000k -minrate:v 0
-bufsize:v 1835008
-ar 48000
-codec:a ac3 -b:a 448k
DV
pal:
-f dv
-s 720x576 -pix_fmt yuv420p -r 25
-ar 48000 -ac 2
ntsc:
-f dv
-s 720x480 -pix_fmt yuv411p -r 30000/1001
-ar 48000 -ac 2
film:
-f dv
-s 720x480 -pix_fmt yuv411p -r 24000/1001
-ar 48000 -ac 2
The dv50 target is identical to the dv target except that the pixel format
set is yuv422p for all three standards.
Any user-set value for a parameter above will override the target preset
value. In that case, the output may not comply with the target standard.
-dn (input/output)
As an input option, blocks all data streams of a file from being filtered
or being automatically selected or mapped for any output. See
-discard option to disable streams individually.
As an output option, disables data recording i.e. automatic selection or
mapping of any data stream. For full manual control see the -map option.
-dframes number (output)
Set the number of data frames to output. This is an obsolete alias for
-frames:d, which you should use instead.
-frames[:stream_specifier] framecount (output,per-stream)
Stop writing to the stream after framecount frames.
-q[:stream_specifier] q (output,per-stream)
-qscale[:stream_specifier] q (output,per-stream)
Use fixed quality scale (VBR). The meaning of q/qscale is codec
-dependent. If qscale is used without a stream_specifier then it applies
only to the video stream, this is to maintain compatibility with previous
behavior and as specifying the same codec specific value to 2 different
codecs that is audio and video generally is not what is intended when no
stream_specifier is used.
-filter[:stream_specifier] filtergraph (output,per-stream)
Create the filtergraph specified by filtergraph and use it to filter the stream.
filtergraph is a description of the filtergraph to apply to the stream, and
must have a single input and a single output of the same type of the stream.
In the filtergraph, the input is associated to the label in, and the output
to the label out. See the ffmpeg-filters manual for more information about
the filtergraph syntax.
See the -filter_complex option if you want to create filtergraphs with
multiple inputs and/or outputs.
-filter_script[:stream_specifier] filename (output,per-stream)
This option is similar to -filter, the only difference is that its argument
is the name of the file from which a filtergraph description is to be read.
-reinit_filter[:stream_specifier] integer (input,per-stream)
This boolean option determines if the filtergraph(s) to which this stream
is fed gets reinitialized when input frame parameters change mid -stream.
This option is enabled by default as most video and all audio filters cannot
handle deviation in input frame properties. Upon reinitialization, existing
filter state is lost, like e.g. the frame count n reference available in
some filters. Any frames buffered at time of reinitialization are lost.
The properties where a change triggers reinitialization are, for video, frame
resolution or pixel format; for audio, sample format, sample rate, channel
count or channel layout.
-filter_threads nb_threads (global)
Defines how many threads are used to process a filter pipeline. Each
pipeline will produce a thread pool with this many threads available for
parallel processing. The default is the number of available CPUs.
-pre[:stream_specifier] preset_name (output,per-stream)
Specify the preset for matching stream(s).
-stats (global)
Print encoding progress/statistics. It is on by default, to explicitly
disable it you need to specify -nostats.
-stats_period time (global)
Set period at which encoding progress/statistics are updated. Default is 0.5
seconds.
-progress url (global)
Send program-friendly progress information to url.
Progress information is written periodically and at the end of the encoding
process. It is made of "key=value" lines. key consists of only alphanumeric
characters. The last key of a sequence of progress information is always
"progress". The update period is set using -stats_period.
-stdin
Enable interaction on standard input. On by default unless standard input
is used as an input. To explicitly disable interaction you need to specify
-nostdin.
Disabling interaction on standard input is useful, for example, if ffmpeg
is in the background process group. Roughly the same result can be achieved
with ffmpeg ... < /dev/null but it requires a shell.
-debug_ts (global)
Print timestamp information. It is off by default. This option is mostly
useful for testing and debugging purposes, and the output format may change
from one version to another, so it should not be employed by portable scripts.
See also the option -fdebug ts.
-attach filename (output)
Add an attachment to the output file. This is supported by a few formats
like Matroska for e.g. fonts used in rendering subtitles. Attachments are
implemented as a specific type of stream, so this option will add a new
stream to the file. It is then possible to use per-stream options on this
stream in the usual way. Attachment streams created with this option will
be created after all the other streams (i.e. those created with -map or
automatic mappings).
Note that for Matroska you also have to set the mimetype metadata tag:
ffmpeg -i INPUT -attach DejaVuSans.ttf -metadata:s:2
mimetype=application/x-truetype-font out.mkv
(assuming that the attachment stream will be third in the output file).
-dump_attachment[:stream_specifier] filename (input,per-stream)
Extract the matching attachment stream into a file named filename. If
filename is empty, then the value of the filename metadata tag will be used.
E.g. to extract the first attachment to a file named ’out.ttf’:
ffmpeg -dump_attachment:t:0 out.ttf -i INPUT
To extract all attachments to files determined by the filename tag:
ffmpeg -dump_attachment:t "" -i INPUT
Technical note – attachments are implemented as codec extradata, so this
option can actually be used to extract extradata from any stream, not just
attachments.
5.5 Video Options
-vframes number (output)
Set the number of video frames to output. This is an obsolete alias for
-frames:v, which you should use instead.
-r[:stream_specifier] fps (input/output,per-stream)
Set frame rate (Hz value, fraction or abbreviation).
As an input option, ignore any timestamps stored in the file and instead
generate timestamps assuming constant frame rate fps. This is not the same
as the -framerate option used for some input formats like image2 or v4l2
(it used to be the same in older versions of FFmpeg). If in doubt use
-framerate instead of the input option -r.
As an output option:
video encoding
Duplicate or drop frames right before encoding them to achieve constant
output frame rate fps.
video streamcopy
Indicate to the muxer that fps is the stream frame rate. No data is
dropped or duplicated in this case. This may produce invalid files if
fps does not match the actual stream frame rate as determined by packet
timestamps. See also the setts bitstream filter.
-fpsmax[:stream_specifier] fps (output,per-stream)
Set maximum frame rate (Hz value, fraction or abbreviation).
Clamps output frame rate when output framerate is auto-set and is higher
than this value. Useful in batch processing or when input framerate is
wrongly detected as very high. It cannot be set together with -r. It is
ignored during streamcopy.
-s[:stream_specifier] size (input/output,per-stream)
Set frame size.
As an input option, this is a shortcut for the video_size private option,
recognized by some demuxers for which the frame size is either not stored in
the file or is configurable – e.g. raw video or video grabbers.
As an output option, this inserts the scale video filter to the end of the
corresponding filtergraph. Please use the scale filter directly to insert it
at the beginning or some other place.
The format is ‘wxh’ (default - same as source).
-aspect[:stream_specifier] aspect (output,per-stream)
Set the video display aspect ratio specified by aspect.
aspect can be a floating point number string, or a string of the form
num:den, where num and den are the numerator and denominator of the aspect
ratio. For example "4:3", "16:9", "1.3333", and "1.7777" are valid argument
values.
If used together with -vcodec copy, it will affect the aspect ratio stored
at container level, but not the aspect ratio stored in encoded frames, if it
exists.
-display_rotation[:stream_specifier] rotation (input,per-stream)
Set video rotation metadata.
Rotation is a decimal number specifying the amount in degree by which the
video should be rotated counter-clockwise before being displayed.
This option overrides the rotation/display transform metadata stored in the
file, if any. When the video is being transcoded (rather than copied) and
-autorotate is enabled, the video will be rotated at the filtering stage.
Otherwise, the metadata will be written into the output file if the muxer
supports it.
If the -display_hflip and/or -display_vflip options are given, they are
applied after the rotation specified by this option.
-display_hflip[:stream_specifier] (input,per-stream)
Set whether on display the image should be horizontally flipped.
See the -display_rotation option for more details.
-display_vflip[:stream_specifier] (input,per-stream)
Set whether on display the image should be vertically flipped.
See the -display_rotation option for more details.
-vn (input/output)
As an input option, blocks all video streams of a file from being filtered
or being automatically selected or mapped for any output. See -discard
option to disable streams individually.
As an output option, disables video recording i.e. automatic selection or
mapping of any video stream. For full manual control see the -map option.
-vcodec codec (output)
Set the video codec. This is an alias for -codec:v.
-pass[:stream_specifier] n (output,per-stream)
Select the pass number (1 or 2). It is used to do two-pass video encoding.
The statistics of the video are recorded in the first pass into a log file
(see also the option -passlogfile), and in the second pass that log file is
used to generate the video at the exact requested bitrate. On pass 1, you
may just deactivate audio and set output to null, examples for Windows and Unix:
ffmpeg -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y NUL
ffmpeg -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null
-passlogfile[:stream_specifier] prefix (output,per-stream)
Set two-pass log file name prefix to prefix, the default file name prefix is
“ffmpeg2pass”. The complete file name will be PREFIX-N.log, where N is a
number specific to the output stream
-vf filtergraph (output)
Create the filtergraph specified by filtergraph and use it to filter the stream.
This is an alias for -filter:v, see the -filter option.
-autorotate
Automatically rotate the video according to file metadata. Enabled by
default, use -noautorotate to disable it.
-autoscale
Automatically scale the video according to the resolution of first frame.
Enabled by default, use -noautoscale to disable it. When autoscale is
disabled, all output frames of filter graph might not be in the same
resolution and may be inadequate for some encoder/muxer. Therefore, it is
not recommended to disable it unless you really know what you are doing.
Disable autoscale at your own risk.
5.6 Advanced Video options
-pix_fmt[:stream_specifier] format (input/output,per-stream)
Set pixel format. Use -pix_fmts to show all the supported pixel formats. If
the selected pixel format can not be selected, ffmpeg will print a warning
and select the best pixel format supported by the encoder. If pix_fmt is
prefixed by a +, ffmpeg will exit with an error if the requested pixel
format can not be selected, and automatic conversions inside filtergraphs
are disabled. If pix_fmt is a single +, ffmpeg selects the same pixel format
as the input (or graph output) and automatic conversions are disabled.
-sws_flags flags (input/output)
Set default flags for the libswscale library. These flags are used by
automatically inserted scale filters and those within simple filtergraphs,
if not overridden within the filtergraph definition.
See the (ffmpeg-scaler)ffmpeg-scaler manual for a list of scaler options.
-rc_override[:stream_specifier] override (output,per-stream)
Rate control override for specific intervals, formatted as "int,int,int"
list separated with slashes. Two first values are the beginning and end
frame numbers, last one is quantizer to use if positive, or quality factor
if negative.
-psnr
Calculate PSNR of compressed frames. This option is deprecated, pass the
PSNR flag to the encoder instead, using -flags +psnr.
-vstats
Dump video coding statistics to vstats_HHMMSS.log. See the vstats file
format section for the format description.
-vstats_file file
Dump video coding statistics to file. See the vstats file format section for
the format description.
-vstats_version file
Specify which version of the vstats format to use. Default is 2. See the
vstats file format section for the format description.
-top[:stream_specifier] n (output,per-stream)
top=1/bottom=0/auto=-1 field first
-vtag fourcc/tag (output)
Force video tag/fourcc. This is an alias for -tag:v.
-vbsf bitstream_filter
Deprecated see -bsf
-force_key_frames[:stream_specifier] time[,time...] (output,per-stream)
-force_key_frames[:stream_specifier] expr:expr (output,per-stream)
-force_key_frames[:stream_specifier] source (output,per-stream)
-force_key_frames[:stream_specifier] source_no_drop (output,per-stream)
force_key_frames can take arguments of the following form:
time[,time...]
If the argument consists of timestamps, ffmpeg will round the specified
times to the nearest output timestamp as per the encoder time base and
force a keyframe at the first frame having timestamp equal or greater
than the computed timestamp. Note that if the encoder time base is too
coarse, then the keyframes may be forced on frames with timestamps lower
than the specified time. The default encoder time base is the inverse of
the output framerate but may be set otherwise via -enc_time_base.
If one of the times is "chapters[delta]", it is expanded into the time
of the beginning of all chapters in the file, shifted by delta,
expressed as a time in seconds. This option can be useful to ensure that
a seek point is present at a chapter mark or any other designated place
in the output file.
For example, to insert a key frame at 5 minutes, plus key frames 0.1
second before the beginning of every chapter:
-force_key_frames 0:05:00,chapters-0.1
expr:expr
If the argument is prefixed with expr:, the string expr is interpreted like
an expression and is evaluated for each frame. A key frame is forced in case
the evaluation is non-zero.
The expression in expr can contain the following constants:
n
the number of current processed frame, starting from 0
n_forced
the number of forced frames
prev_forced_n
the number of the previous forced frame, it is NAN when no keyframe
was forced yet
prev_forced_t
the time of the previous forced frame, it is NAN when no keyframe
was forced yet
t
the time of the current processed frame
For example to force a key frame every 5 seconds, you can specify:
-force_key_frames expr:gte(t,n_forced*5)
To force a key frame 5 seconds after the time of the last forced one,
starting from second 13:
-force_key_frames expr:if(isnan(prev_forced
_t),gte(t,13),gte(t,prev_forced_t+5))
source
If the argument is source, ffmpeg will force a key frame if the current
frame being encoded is marked as a key frame in its source.
source_no_dro
If the argument is source_no_drop, ffmpeg will force a key frame if the
current frame being encoded is marked as a key frame in its source. In
cases where this particular source frame has to be dropped, enforce the
next available frame to become a key frame instead.
Note that forcing too many keyframes is very harmful for the lookahead
algorithms of certain encoders: using fixed-GOP options or similar would be
more efficient.
-copyinkf[:stream_specifier] (output,per-stream)
When doing stream copy, copy also non-key frames found at the beginning.
-init_hw_device type[=name][:device[,key=value...]]
Initialise a new hardware device of type type called name, using the given
device parameters. If no name is specified it will receive a default name of
the form "type%d".
The meaning of device and the following arguments depends on the device type:
cuda
device is the number of the CUDA device.
The following options are recognized:
primary_ctx
If set to 1, uses the primary device context instead of creating a
new one.
Examples:
-init_hw_device cuda:
Choose the second device on the system.
-init_hw_device cuda:0,primary_ctx=1
Choose the first device and use the primary device context.
dxva2
device is the number of the Direct3D 9 display adapter.
d3d11va
device is the number of the Direct3D 11 display adapter.
vaapi
device is either an X11 display name, a DRM render node or a
DirectX adapter index. If not specified, it will attempt to open
the default X11 display ($DISPLAY) and then the first DRM render
node (/dev/dri/renderD128), or the default DirectX adapter on Windows.
vdpau
device is an X11 display name. If not specified, it will attempt to open
the default X11 display ($DISPLAY).
qsv
device selects a value in ‘MFX_IMPL_*’. Allowed values are:
auto
sw
hw
auto_any
hw_any
hw2
hw3
hw4
If not specified, ‘auto_any’ is used. (Note that it may be easier to
achieve the desired result for QSV by creating the platform-appropriate
subdevice (‘dxva2’ or ‘d3d11va’ or ‘vaapi’) and then deriving a QSV
device from that.)
Alternatively, ‘child_device_type’ helps to choose platform-appropriate
subdevice type. On Windows ‘d3d11va’ is used as default subdevice type.
Examples:
-init_hw_device qsv:hw,child_device_type=d3d11va
Choose the GPU subdevice with type ‘d3d11va’ and create QSV device
with ‘MFX_IMPL_HARDWARE’.
-init_hw_device qsv:hw,child_device_type=dxva2
Choose the GPU subdevice with type ‘dxva2’ and create QSV device
with ‘MFX_IMPL_HARDWARE’.
opencl
device selects the platform and device as platform_index.device_index.
The set of devices can also be filtered using the key-value pairs to
find only devices matching particular platform or device strings.
The strings usable as filters are:
platform_profile
platform_version
platform_name
platform_vendor
platform_extensions
device_name
device_vendor
driver_version
device_version
device_profile
device_extensions
device_type
The indices and filters must together uniquely select a device.
Examples:
-init_hw_device opencl:0.1
Choose the second device on the first platform.
-init_hw_device opencl:,device_name=Foo9000
Choose the device with a name containing the string Foo9000.
-init_hw_device opencl:1,device_type=gpu,device_extensions=cl_khr_fp16
Choose the GPU device on the second platform supporting the
cl_khr_fp16 extension.
vulkan
If device is an integer, it selects the device by its index in a
system-dependent list of devices. If device is any other string, it
selects the first device with a name containing that string as a
substring.
The following options are recognized:
debug
If set to 1, enables the validation layer, if installed.
linear_images
If set to 1, images allocated by the hwcontext will be linear and
locally mappable.
instance_extensions
A plus separated list of additional instance extensions to enable.
device_extensions
A plus separated list of additional device extensions to enable.
Examples:
-init_hw_device vulkan:1
Choose the second device on the system.
-init_hw_device vulkan:RADV
Choose the first device with a name containing the string RADV.
-init_hw_device vulkan:0,instance_extensions=VK_KHR_wayland_surface+VK_KHR_xcb_surface
Choose the first device and enable the Wayland and XCB instance
extensions.
-init_hw_device type[=name]@source
Initialise a new hardware device of type type called name, deriving it from
the existing device with the name source.
-init_hw_device list
List all hardware device types supported in this build of ffmpeg.
-filter_hw_device name
Pass the hardware device called name to all filters in any filter graph.
This can be used to set the device to upload to with the hwupload filter, or
the device to map to with the hwmap filter. Other filters may also make use
of this parameter when they require a hardware device. Note that this is
typically only required when the input is not already in hardware frames
- when it is, filters will derive the device they require from the context
of the frames they receive as input.
This is a global setting, so all filters will receive the same device.
-hwaccel[:stream_specifier] hwaccel (input,per-stream)
Use hardware acceleration to decode the matching stream(s). The allowed
values of hwaccel are:
none
Do not use any hardware acceleration (the default).
auto
Automatically select the hardware acceleration method.
vdpau
Use VDPAU (Video Decode and Presentation API for Unix)
hardware acceleration.
dxva2
Use DXVA2 (DirectX Video Acceleration) hardware acceleration.
d3d11va
Use D3D11VA (DirectX Video Acceleration) hardware acceleration.
vaapi
Use VAAPI (Video Acceleration API) hardware acceleration.
qsv
Use the Intel QuickSync Video acceleration for video transcoding.
Unlike most other values, this option does not enable accelerated
decoding (that is used automatically whenever a qsv decoder is selected),
but accelerated transcoding, without copying the frames into the system
memory.
For it to work, both the decoder and the encoder must support QSV
acceleration and no filters must be used.
This option has no effect if the selected hwaccel is not available or not
supported by the chosen decoder.
Note that most acceleration methods are intended for playback and will not
be faster than software decoding on modern CPUs. Additionally, ffmpeg will
usually need to copy the decoded frames from the GPU memory into the system
memory, resulting in further performance loss. This option is thus mainly
useful for testing.
-hwaccel_device[:stream_specifier] hwaccel_device (input,per-stream)
Select a device to use for hardware acceleration.
This option only makes sense when the -hwaccel option is also specified.
It can either refer to an existing device created with -init_hw_device by
name, or it can create a new device as if ‘-init_hw_device’ type:hwaccel_device
were called immediately before.
-hwaccels
List all hardware acceleration components enabled in this build of ffmpeg.
Actual runtime availability depends on the hardware and its suitable driver
being installed.
-fix_sub_duration_heartbeat[:stream_specifier]
Set a specific output video stream as the heartbeat stream according to
which to split and push through currently in-progress subtitle upon receipt
of a random access packet.
This lowers the latency of subtitles for which the end packet or the
following subtitle has not yet been received. As a drawback, this will most
likely lead to duplication of subtitle events in order to cover the full
duration, so when dealing with use cases where latency of when the subtitle
event is passed on to output is not relevant this option should not be utilized.
Requires -fix_sub_duration to be set for the relevant input subtitle stream
for this to have any effect, as well as for the input subtitle stream having
to be directly mapped to the same output in which the heartbeat stream resides.
5.7 Audio Options
-aframes number (output)
Set the number of audio frames to output. This is an obsolete alias for
-frames:a, which you should use instead.
-ar[:stream_specifier] freq (input/output,per-stream)
Set the audio sampling frequency. For output streams it is set by default to
the frequency of the corresponding input stream. For input streams this
option only makes sense for audio grabbing devices and raw demuxers and is
mapped to the corresponding demuxer options.
-aq q (output)
Set the audio quality (codec-specific, VBR). This is an alias for -q:a.
-ac[:stream_specifier] channels (input/output,per-stream
Set the number of audio channels. For output streams it is set by default
to the number of input audio channels. For input streams this option only
makes sense for audio grabbing devices and raw demuxers and is mapped to the
corresponding demuxer options.
-an (input/output)
As an input option, blocks all audio streams of a file from being filtered
or being automatically selected or mapped for any output. See -discard
option to disable streams individually.
As an output option, disables audio recording i.e. automatic selection or
mapping of any audio stream. For full manual control see the -map option.
-acodec codec (input/output
Set the audio codec. This is an alias for -codec:a.
-sample_fmt[:stream_specifier] sample_fmt (output,per-stream)
Set the audio sample format. Use -sample_fmts to get a list of supported
sample formats.
-af filtergraph (output
Create the filtergraph specified by filtergraph and use it to filter the
stream.
This is an alias for -filter:a, see the -filter option.
5.8 Advanced Audio options
-atag fourcc/tag (output)
Force audio tag/fourcc. This is an alias for -tag:a.
-absf bitstream_filter
Deprecated, see -bsf
-guess_layout_max channels (input,per-stream)
If some input channel layout is not known, try to guess only if it
corresponds to at most the specified number of channels. For example, 2
tells to ffmpeg to recognize 1 channel as mono and 2 channels as stereo but
not 6 channels as 5.1. The default is to always try to guess. Use 0 to
disable all guessing.
5.9 Subtitle options
-scodec codec (input/output)
Set the subtitle codec. This is an alias for -codec:s.
-sn (input/output
As an input option, blocks all subtitle streams of a file from being
filtered or being automatically selected or mapped for any output. See
-discard option to disable streams individually.
As an output option, disables subtitle recording i.e. automatic selection or
mapping of any subtitle stream. For full manual control see the -map option.
-sbsf bitstream_filter
Deprecated, see -bsf
5.10 Advanced Subtitle options
-fix_sub_duration
Fix subtitles durations. For each subtitle, wait for the next packet in the
same stream and adjust the duration of the first to avoid overlap. This is
necessary with some subtitles codecs, especially DVB subtitles, because the
duration in the original packet is only a rough estimate and the end is
actually marked by an empty subtitle frame. Failing to use this option when
necessary can result in exaggerated durations or muxing failures due to
non-monotonic timestamps.
Note that this option will delay the output of all data until the next
subtitle packet is decoded: it may increase memory consumption and
latency
a lot.
-canvas_size siz
Set the size of the canvas used to render subtitles.
5.11 Advanced options
-map [-]input_file_id[:stream_specifier][?] | [linklabel] (output)
Create one or more streams in the output file. This option has two forms for
specifying the data source(s): the first selects one or more streams from so
me input file (specified with -i), the second takes an output from some c
omplex filtergraph (specified with -filter_complex or -filter_complex_script).
In the first form, an output stream is created for every stream from the
input file with the index input_file_id. If stream_specifier is given, only
those streams that match the specifier are used (see the Stream specifiers
section for the stream_specifier syntax).
A - character before the stream identifier creates a "negative" mapping. It
disables matching streams from already created mappings.
A trailing ? after the stream index will allow the map to be optional: if
the map matches no streams the map will be ignored instead of failing.
Note
the map will still fail if an invalid input file index is used; such as if
the map refers to a non-existent input.
An alternative [linklabel] form will map outputs from complex filter graphs
(see the -filter_complex option) to the output file. linklabel must
correspond to a defined output link label in the graph.
This option may be specified multiple times, each adding more streams to the
output file. Any given input stream may also be mapped any number of times
as a source for different output streams, e.g. in order to use different
encoding options and/or filters. The streams are created in the output in
the same order in which the -map options are given on the commandline.
Using this option disables the default mappings for this output file.
Examples:
map everything
To map ALL streams from the first input file to output
ffmpeg -i INPUT -map 0 output
select specific stream
If you have two audio streams in the first input file, these streams are
identified by 0:0 and 0:1. You can use -map to select which streams to
place in an output file. For example:
ffmpeg -i INPUT -map 0:1 out.wa
will map the second input stream in INPUT to the (single) output stream
in out.wav.
create multiple streams
To select the stream with index 2 from input file a.mov (specified by
the identifier 0:2), and stream with index 6 from input b.mov (specified
by the identifier 1:6), and copy them to the output file out.mov:
ffmpeg -i a.mov -i b.mov -c copy -map 0:2 -map 1:6 out.mov
create multiple streams 2
To select all video and the third audio stream from an input file:
ffmpeg -i INPUT -map 0:v -map 0:a:2 OUTPUT
negative map
To map all the streams except the second audio, use negative mappings
ffmpeg -i INPUT -map 0 -map -0:a:1 OUTPUT
optional map
To map the video and audio streams from the first input, and using the
trailing ?, ignore the audio mapping if no audio streams exist in the
first input:
ffmpeg -i INPUT -map 0:v -map 0:a? OUTPUT
map by language
To pick the English audio stream:
ffmpeg -i INPUT -map 0:m:language:eng OUTPUT
-ignore_unknow
Ignore input streams with unknown type instead of failing if copying such
streams is attempted.
-copy_unknown
Allow input streams with unknown type to be copied instead of failing if
copying such streams is attempted.
-map_channel [input_file_id.stream_specifier.channel_id|
-1][?][:output_file_id.stream_specifier]
This option is deprecated and will be removed. It can be replaced by the
pan filter. In some cases it may be easier to use some combination of the
channelsplit, channelmap, or amerge filters.
Map an audio channel from a given input to an output. If
output_file_id.stream_specifier is not set, the audio channel will be mapped
on all the audio streams.
Using "-1" instead of input_file_id.stream_specifier.channel_id will map a
muted channel.
A trailing ? will allow the map_channel to be optional: if the map_channel
matches no channel the map_channel will be ignored instead of failing.
For example, assuming INPUT is a stereo audio file, you can switch the two
audio channels with the following command:
ffmpeg -i INPUT -map_channel 0.0.1 -map_channel 0.0.0 OUTPU
If you want to mute the first channel and keep the second:
ffmpeg -i INPUT -map_channel -1 -map_channel 0.0.1 OUTPUT
The order of the "-map_channel" option specifies the order of the channels
in the output stream. The output channel layout is guessed from the number
of channels mapped (mono if one "-map_channel", stereo if two, etc.). Using
"-ac" in combination of "-map_channel" makes the channel gain levels to be
updated if input and output channel layouts don’t match (for instance two
"-map_channel" options and "-ac 6").
You can also extract each channel of an input to specific outputs; the
following command extracts two channels of the INPUT audio stream (file 0,
stream 0) to the respective OUTPUT_CH0 and OUTPUT_CH1 outputs:
ffmpeg -i INPUT -map_channel 0.0.0 OUTPUT_CH0
-map_channel 0.0.1 OUTPUT_CH1
The following example splits the channels of a stereo input into two
separate streams, which are put into the same output file:
ffmpeg -i stereo.wav -map 0:0 -map 0:0
-map_channel 0.0.0:0.0 -map_channel 0.0.1:0.1 -y out.ogg
Note that currently each output stream can only contain channels from a
single input stream; you can’t for example use "-map_channel" to pick
multiple input audio channels contained in different streams (from the same
or different files) and merge them into a single output stream. It is
therefore not currently possible, for example, to turn two separate mono
streams into a single stereo stream. However splitting a stereo stream into
two single channel mono streams is possible.
If you need this feature, a possible workaround is to use the amerge filter.
For example, if you need to merge a media (here input.mkv) with 2 mono
audio streams into one single stereo channel audio stream (and keep the
video stream), you can use the following command:
ffmpeg -i input.mkv -filter_complex "[0:1] [0:2] amerge"
-c:a pcm_s16le -c:v copy output.mkv
To map the first two audio channels from the first input, and using the
trailing ?, ignore the audio channel mapping if the first input is mono
instead of stereo:
ffmpeg -i INPUT -map_channel 0.0.0 -map_channel 0.0.1? OUTPUT
-map_metadata[:metadata_spec_out] infile[:metadata_spec_in]
(output,per -metadata)
Set metadata information of the next output file from infile. Note that
those are file indices (zero-based), not filenames. Optional
metadata_spec_in/out parameters specify, which metadata to copy. A metadata
specifier can have the following forms:
g
global metadata, i.e. metadata that applies to the whole file
s[:stream_spec]
per-stream metadata. stream_spec is a stream specifier as described in
the Stream specifiers chapter. In an input metadata specifier, the first
matching stream is copied from. In an output metadata specifier, all
matching streams are copied to.
c:chapter_index
per-chapter metadata. chapter_index is the zero-based chapter index.
p:program_index
per-program metadata. program_index is the zero-based program index.
If metadata specifier is omitted, it defaults to global.
By default, global metadata is copied from the first input file, per -stream
and per-chapter metadata is copied along with streams/chapters. These
default mappings are disabled by creating any mapping of the relevant type.
A negative file index can be used to create a dummy mapping that just
disables automatic copying.
For example to copy metadata from the first stream of the input file to
global metadata of the output file:
ffmpeg -i in.ogg -map_metadata 0:s:0 out.mp3
To do the reverse, i.e. copy global metadata to all audio streams:
ffmpeg -i in.mkv -map_metadata:s:a 0:g out.mkv
Note that simple 0 would work as well in this example, since global metadata
is assumed by default.
-map_chapters input_file_index (output)
Copy chapters from input file with index input_file_index to the next output
file. If no chapter mapping is specified, then chapters are copied from the
first input file with at least one chapter. Use a negative file index to
disable any chapter copying.
-benchmark (global)
Show benchmarking information at the end of an encode. Shows real, system
and user time used and maximum memory consumption. Maximum memory
consumption is not supported on all systems, it will usually display as 0 if
not supported.
-benchmark_all (global)
Show benchmarking information during the encode. Shows real, system and user
time used in various steps (audio/video encode/decode).
-timelimit duration (global
Exit after ffmpeg has been running for duration seconds in CPU user time.
-dump (global
Dump each input packet to stderr.
-hex (global)
When dumping packets, also dump the payload.
-readrate speed (input)
Limit input read speed.
Its value is a floating-point positive number which represents the maximum
duration of media, in seconds, that should be ingested in one second of
wallclock time. Default value is zero and represents no imposed limitation
on speed of ingestion. Value 1 represents real-time speed and is equivalent
to -re.
Mainly used to simulate a capture device or live input stream (e.g. when
reading from a file). Should not be used with a low value when input is an
actual capture device or live stream as it may cause packet loss.
It is useful for when flow speed of output packets is important, such as
live streaming.
-re (input)
Read input at native frame rate. This is equivalent to setting -readrate 1.
-readrate_initial_burst seconds
Set an initial read burst time, in seconds, after which -re/-readrate will
be enforced.
-vsync parameter (global)
-fps_mode[:stream_specifier] parameter (output,per-stream)
Set video sync method / framerate mode. vsync is applied to all output video
streams but can be overridden for a stream by setting fps_mode. vsync is
deprecated and will be removed in the future.
For compatibility reasons some of the values for vsync can be specified as
numbers (shown in parentheses in the following table).
passthrough (0)
Each frame is passed with its timestamp from the demuxer to the muxer.
cfr (1)
Frames will be duplicated and dropped to achieve exactly the requested
constant frame rate.
vfr (2)
Frames are passed through with their timestamp or dropped so as to prevent
2 frames from having the same timestamp.
drop
As passthrough but destroys all timestamps, making the muxer generate
fresh timestamps based on frame-rate.
auto (-1)
Chooses between cfr and vfr depending on muxer capabilities. This is the
default method.
Note that the timestamps may be further modified by the muxer, after this.
For example, in the case that the format option avoid_negative_ts is enabled.
With -map you can select from which stream the timestamps should be taken.
You can leave either video or audio unchanged and sync the remaining
stream(s) to the unchanged one.
-frame_drop_threshold parameter
Frame drop threshold, which specifies how much behind video frames can be
before they are dropped. In frame rate units, so 1.0 is one frame. The
default is -1.1. One possible usecase is to avoid framedrops in case of
noisy timestamps or to increase frame drop precision in case of exact
timestamps.
-apad parameters (output,per-stream)
Pad the output audio stream(s). This is the same as applying -af apad.
Argument is a string of filter parameters composed the same as with the
apad filter. -shortest must be set for this output for the option to take
effect.
-copyts
Do not process input timestamps, but keep their values without trying to
sanitize them. In particular, do not remove the initial start time offset value.
Note that, depending on the vsync option or on specific muxer processing
(e.g. in case the format option avoid_negative_ts is enabled) the output
timestamps may mismatch with the input timestamps even when this option is
selected.
-start_at_zer
When used with copyts, shift input timestamps so they start at zero.
This means that using e.g. -ss 50 will make output timestamps start at 50
seconds, regardless of what timestamp the input file started at.
-copytb mode
Specify how to set the encoder timebase when stream copying. mode is an
integer numeric value, and can assume one of the following values:
1
Use the demuxer timebase.
The time base is copied to the output encoder from the corresponding input
demuxer. This is sometimes required to avoid non monotonically increasing
timestamps when copying video streams with variable frame rate.
0
Use the decoder timebase.
The time base is copied to the output encoder from the corresponding input
decoder.
-1
Try to make the choice automatically, in order to generate a sane output.
Default value is -1.
-enc_time_base[:stream_specifier] timebase (output,per-stream
Set the encoder timebase. timebase can assume one of the following
values:
0
Assign a default value according to the media type.
For video - use 1/framerate, for audio - use 1/samplerate.
demux
Use the timebase from the demuxer.
filter
Use the timebase from the filtergraph.
a positive number
Use the provided number as the timebase.
This field can be provided as a ratio of two integers (e.g. 1:24,1:48000)
or as a decimal number (e.g. 0.04166, 2.0833e-5)
Default value is 0.
-bitexact (input/output
Enable bitexact mode for (de)muxer and (de/en)coder
-shortest (output)
Finish encoding when the shortest output stream ends.
Note that this option may require buffering frames, which introduces extra
latency. The maximum amount of this latency may be controlled with the
-shortest_buf_duration option.
-shortest_buf_duration duration (output
The -shortest option may require buffering potentially large amounts of data
when at least one of the streams is "sparse" (i.e. has large gaps between
frames – this is typically the case for subtitles).
This option controls the maximum duration of buffered frames in seconds.
Larger values may allow the -shortest option to produce more accurate
results, but increase memory use and latency.
The default value is 10 seconds.
-dts_delta_threshold threshol
Timestamp discontinuity delta threshold, expressed as a decimal number of
seconds.
The timestamp discontinuity correction enabled by this option is only
applied to input formats accepting timestamp discontinuity (for which the
AV_FMT_DISCONT flag is enabled), e.g. MPEG-TS and HLS, and is automatically
disabled when employing the -copy_ts option (unless wrapping is detected).
If a timestamp discontinuity is detected whose absolute value is greater
than threshold, ffmpeg will remove the discontinuity by
decreasing/increasing the current DTS and PTS by the corresponding delta
value.
The default value is 10.
-dts_error_threshold threshol
Timestamp error delta threshold, expressed as a decimal number of seconds.
The timestamp correction enabled by this option is only applied to input
formats not accepting timestamp discontinuity (for which the AV_FMT_DISCONT
flag is not enabled).
If a timestamp discontinuity is detected whose absolute value is greater
than threshold, ffmpeg will drop the PTS/DTS timestamp value.
The default value is 3600*30 (30 hours), which is arbitrarily picked and
quite conservative.
-muxdelay seconds (output)
Set the maximum demux-decode delay.
-muxpreload seconds (output
Set the initial demux-decode delay.
-streamid output-stream-index:new-value (output)
Assign a new stream-id value to an output stream. This option should be
specified prior to the output filename to which it applies. For the
situation where multiple output files exist, a streamid may be reassigned
to a different value.
For example, to set the stream 0 PID to 33 and the stream 1 PID to 36 for
an output mpegts file:
ffmpeg -i inurl -streamid 0:33 -streamid 1:36 out.t
-bsf[:stream_specifier] bitstream_filters (output,per-stream
Set bitstream filters for matching streams. bitstream_filters is a
comma-separated list of bitstream filters. Use the -bsfs option to get the
list of bitstream filters.
ffmpeg -i h264.mp4 -c:v copy -bsf:v h264_mp4toannexb -an out.h26
ffmpeg -i file.mov -an -vn -bsf:s mov2textsub -c:s copy
-f rawvideo sub.tx
-tag[:stream_specifier] codec_tag (input/output,per-stream)
Force a tag/fourcc for matching streams.
-timecode hh:mm:ssSEPf
Specify Timecode for writing. SEP is ’:’ for non drop timecode
and ’;’ (or ’.’) for drop.
ffmpeg -i input.mpg -timecode 01:02:03.04 -r 30000/1001
-s ntsc output.mpg
-filter_complex filtergraph (global
Define a complex filtergraph, i.e. one with arbitrary number of inputs
and/or outputs. For simple graphs – those with one input and one output of
the same type – see the -filter options. filtergraph is a description of the
filtergraph, as described in the “Filtergraph syntax” section of the
ffmpeg-filters manual.
Input link labels must refer to input streams using the
[file_index:stream_specifier] syntax (i.e. the same as -map uses). If
stream_specifier matches multiple streams, the first one will be used. An
unlabeled input will be connected to the first unused input stream of the
matching type.
Output link labels are referred to with -map. Unlabeled outputs are added
to the first output file.
Note that with this option it is possible to use only lavfi sources without
normal input files.
For example, to overlay an image over video
ffmpeg -i video.mkv -i image.png -filter_complex
'[0:v][1:v]overlay[out]' -map '[out]' out.mkv
Here [0:v] refers to the first video stream in the first input file, which
is linked to the first (main) input of the overlay filter. Similarly the
first video stream in the second input is linked to the second (overlay)
input of overlay.
Assuming there is only one video stream in each input file, we can omit
input labels, so the above is equivalent to
ffmpeg -i video.mkv -i image.png -filter_complex
'overlay[out]' -map '[out]' out.mkv
Furthermore we can omit the output label and the single output from the
filter graph will be added to the output file automatically, so we can
simply write
ffmpeg -i video.mkv -i image.png -filter_complex 'overlay' out.mkv
As a special exception, you can use a bitmap subtitle stream as input: it
will be converted into a video with the same size as the largest video in
the file, or 720x576 if no video is present. Note that this is an
experimental and temporary solution. It will be removed once libavfilter
has proper support for subtitles.
For example, to hardcode subtitles on top of a DVB-T recording stored in
MPEG-TS format, delaying the subtitles by 1 second:
ffmpeg -i input.ts -filter_complex \
'[#0x2ef] setpts=PTS+1/TB [sub] ; [#0x2d0] [sub] overlay' \
-sn -map '#0x2dc' output.mkv
(0x2d0, 0x2dc and 0x2ef are the MPEG-TS PIDs of respectively the video,
audio and subtitles streams; 0:0, 0:3 and 0:7 would have worked too)
To generate 5 seconds of pure red video using lavfi color source:
ffmpeg -filter_complex 'color=c=red' -t 5 out.mkv
-filter_complex_threads nb_threads (global
Defines how many threads are used to process a filter_complex graph. Similar
to filter_threads but used for -filter_complex graphs only. The default is
the number of available CPUs.
-lavfi filtergraph (global
Define a complex filtergraph, i.e. one with arbitrary number of inputs
and/or outputs. Equivalent to -filter_complex.
-filter_complex_script filename (global)
This option is similar to -filter_complex, the only difference is that its
argument is the name of the file from which a complex filtergraph description
is to be read.
-accurate_seek (input)
This option enables or disables accurate seeking in input files with the
-ss option. It is enabled by default, so seeking is accurate when
transcoding. Use -noaccurate_seek to disable it, which may be useful e.g.
when copying some streams and transcoding the others.
-seek_timestamp (input)
This option enables or disables seeking by timestamp in input files with the
-ss option. It is disabled by default. If enabled, the argument to the -ss
option is considered an actual timestamp, and is not offset by the start
time of the file. This matters only for files which do not start from
timestamp 0, such as transport streams.
-thread_queue_size size (input/output)
For input, this option sets the maximum number of queued packets when
reading from the file or device. With low latency / high rate live streams,
packets may be discarded if they are not read in a timely manner; setting
this value can force ffmpeg to use a separate input thread and read packets
as soon as they arrive. By default ffmpeg only does this if multiple inputs
are specified.
For output, this option specified the maximum number of packets that may be
queued to each muxing thread.
-sdp_file file (global)
Print sdp information for an output stream to file. This allows dumping sdp
information when at least one output isn’t an rtp stream. (Requires at least
one of the output formats to be rtp).
-discard (input)
Allows discarding specific streams or frames from streams. Any input stream
can be fully discarded, using value all whereas selective discarding of
frames from a stream occurs at the demuxer and is not supported by all
demuxers.
non
Discard no frame.
default
Default, which discards no frames.
nore
Discard all non-reference frames.
bidi
Discard all bidirectional frames.
noke
Discard all frames excepts keyframes.
all
Discard all frames.
-abort_on flags (global)
Stop and abort on various conditions. The following flags are available:
empty_output
No packets were passed to the muxer, the output is empty.
empty_output_stream
No packets were passed to the muxer in some of the output streams.
-max_error_rate (global)
Set fraction of decoding frame failures across all inputs which when
crossed
ffmpeg will return exit code 69. Crossing this threshold does not terminate
processing. Range is a floating-point number between 0 to 1. Default is 2/3.
-xerror (global)
Stop and exit on error
-max_muxing_queue_size packets (output,per-stream)
When transcoding audio and/or video streams, ffmpeg will not begin writing
into the output until it has one packet for each such stream. While waiting
for that to happen, packets for other streams are buffered. This option
sets the size of this buffer, in packets, for the matching output stream.
The default value of this option should be high enough for most uses, so
only touch this option if you are sure that you need it.
-muxing_queue_data_threshold bytes (output,per-stream
This is a minimum threshold until which the muxing queue size is not taken
into account. Defaults to 50 megabytes per stream, and is based on the
overall size of packets passed to the muxer.
-auto_conversion_filters (global)
Enable automatically inserting format conversion filters in all filter
graphs, including those defined by -vf, -af, -filter_complex and -lavfi. If
filter format negotiation requires a conversion, the initialization of the
filters will fail. Conversions can still be performed by inserting the
relevant conversion filter (scale, aresample) in the graph. On by default,
to explicitly disable it you need to specify -noauto_conversion_filters.
-bits_per_raw_sample[:stream_specifier] value (output,per-stream)
Declare the number of bits per raw sample in the given output stream to be
value. Note that this option sets the information provided to the
encoder/muxer, it does not change the stream to conform to this value.
Setting values that do not match the stream properties may result in
encoding failures or invalid output files.
-stats_enc_pre[:stream_specifier] path (output,per-stream)
-stats_enc_post[:stream_specifier] path (output,per-stream)
-stats_mux_pre[:stream_specifier] path (output,per-stream)
Write per-frame encoding information about the matching streams into the
file given by path.
-stats_enc_pre writes information about raw video or audio frames right
before they are sent for encoding, while -stats_enc_post writes information
about encoded packets as they are received from the encoder.
-stats_mux_pre writes information about packets just as they are about to be
sent to the muxer. Every frame or packet produces one line in the specified
file. The format of this line is controlled by
-stats_enc_pre_fmt / -stats_enc_post_fmt / -stats_mux_pre_fmt.
When stats for multiple streams are written into a single file, the lines
corresponding to different streams will be interleaved. The precise order
of this interleaving is not specified and not guaranteed to remain stable
between different invocations of the program, even with the same options.
-stats_enc_pre_fmt[:stream_specifier] format_spec (output,per-stream)
-stats_enc_post_fmt[:stream_specifier] format_spec (output,per-stream)
-stats_mux_pre_fmt[:stream_specifier] format_spec (output,per-stream)
Specify the format for the lines written with -stats_enc_pre /
-stats_enc_post / -stats_mux_pre.
format_spec is a string that may contain directives of the form {fmt}.
format_spec is backslash-escaped — use \{, \}, and \\ to write a literal
{, }, or \, respectively, into the output.
The directives given with fmt may be one of the following:
fidx
Index of the output file.
sid
Index of the output stream in the file.
n
Frame number. Pre-encoding: number of frames sent to the encoder so far.
Post-encoding: number of packets received from the encoder so far.
Muxing: number of packets submitted to the muxer for this stream so far.
ni
Input frame number. Index of the input frame (i.e. output by a decoder)
that corresponds to this output frame or packet. -1 if unavailable.
t
Timebase in which this frame/packet’s timestamps are expressed, as a
rational number num/den. Note that encoder and muxer may use different
timebases.
tbi
Timebase for ptsi, as a rational number num/den. Available when ptsi is
available, 0/1 otherwise.
pt
Presentation timestamp of the frame or packet, as an integer. Should be
multiplied by the timebase to compute presentation time.
ptsi
Presentation timestamp of the input frame (see ni), as an integer.
Should be multiplied by tbi to compute presentation time. Printed as
(2^63 - 1 = 9223372036854775807) when not available.
t
Presentation time of the frame or packet, as a decimal number. Equal to
pts multiplied by tb.
ti
Presentation time of the input frame (see ni), as a decimal number.
Equal to ptsi multiplied by tbi. Printed as inf when not available.
dts (packet)
Decoding timestamp of the packet, as an integer. Should be multiplied by
the timebase to compute presentation time.
dt (packet)
Decoding time of the frame or packet, as a decimal number. Equal to dts
multiplied by tb.
sn (frame,audio)
Number of audio samples sent to the encoder so far.
samp (frame,audio)
Number of audio samples in the frame.
size (packet)
Size of the encoded packet in bytes.
br (packet)
Current bitrate in bits per second. Post-encoding only.
abr (packet)
Average bitrate for the whole stream so far, in bits per second, -1 if
it cannot be determined at this point. Post-encoding only.
Directives tagged with packet may only be used with -stats_enc_post_fmt and
-stats_mux_pre_fmt.
Directives tagged with frame may only be used with -stats_enc_pre_fmt.
Directives tagged with audio may only be used with audio streams.
The default format strings are:
pre-encoding
{fidx} {sidx} {n} {t}
post-encoding
{fidx} {sidx} {n} {t}
In the future, new items may be added to the end of the default formatting
strings. Users who depend on the format staying exactly the same, should
prescribe it manually.
Note that stats for different streams written into the same file may have
different formats.
5.12 Preset files
A preset file contains a sequence of option=value pairs, one for each line,
specifying a sequence of options which would be awkward to specify on the
command line. Lines starting with the hash (’#’) character are ignored and are
used to provide comments. Check the presets directory in the FFmpeg source tree
for examples.
There are two types of preset files: ffpreset and avpreset files.
5.12.1 ffpreset files
ffpreset files are specified with the vpre, apre, spre, and fpre options. The
fpre option takes the filename of the preset instead of a preset name as input
and can be used for any kind of codec. For the vpre, apre, and spre options, the
options specified in a preset file are applied to the currently selected codec
of the same type as the preset option.
The argument passed to the vpre, apre, and spre preset options identifies the
preset file to use according to the following rules:
First ffmpeg searches for a file named arg.ffpreset in the directories
$FFMPEG_DATADIR (if set), and $HOME/.ffmpeg, and in the datadir defined at
configuration time (usually PREFIX/share/ffmpeg) or in a ffpresets folder along
the executable on win32, in that order. For example, if the argument is
libvpx-1080p, it will search for the file libvpx-1080p.ffpreset.
If no such file is found, then ffmpeg will search for a file named
codec_name-arg.ffpreset in the above-mentioned directories, where codec_name is
the name of the codec to which the preset file options will be applied. For
example, if you select the video codec with -vcodec libvpx and use -vpre 1080p,
then it will search for the file libvpx-1080p.ffpreset.
5.12.2 avpreset files
avpreset files are specified with the pre option. They work similar to ffpreset
files, but they only allow encoder- specific options. Therefore, an
option=value pair specifying an encoder cannot be used.
When the pre option is specified, ffmpeg will look for files with the suffix
.avpreset in the directories $AVCONV_DATADIR (if set), and $HOME/.avconv, and in
the datadir defined at configuration time (usually PREFIX/share/ffmpeg), in that
order.
First ffmpeg searches for a file named codec_name-arg.avpreset in the above
-mentioned directories, where codec_name is the name of the codec to which
the preset file options will be applied. For example, if you select the
video codec with -vcodec libvpx and use -pre 1080p, then it will search for
the file libvpx-1080p.avpreset.
If no such file is found, then ffmpeg will search for a file named
arg.avpreset in the same directories.
5.13 vstats file format
The -vstats and -vstats_file options enable generation of a file containing
statistics about the generated video outputs.
The -vstats_version option controls the format version of the generated file.
With version 1 the format is:
frame= FRAME q= FRAME_QUALITY PSNR= PSNR f_size= FRAME_SIZE s_size=
STREAM_SIZEkB time= TIMESTAMP br= BITRATEkbits/s avg_br=
AVERAGE_BITRATEkbits/s
With version 2 the format is:
out= OUT_FILE_INDEX st= OUT_FILE_STREAM_INDEX frame= FRAME_NUMBER q=
FRAME_QUALITYf PSNR= PSNR f_size= FRAME_SIZE s_size= STREAM_SIZEkB time=
TIMESTAMP br= BITRATEkbits/s avg_br= AVERAGE_BITRATEkbits/s
The value corresponding to each key is described below:
avg_br
average bitrate expressed in Kbits/s
br
bitrate expressed in Kbits/s
fram
number of encoded frame
out
out file index
PSN
Peak Signal to Noise Ratio
q
quality of the frame
f_size
encoded packet size expressed as number of bytes
s_size
stream size expressed in KiB
st
out file stream index
time
time of the packet
type
picture type
See also the -stats_enc options for an alternative way to show encoding statistics.
6 Examples
6.1 Video and Audio grabbing
If you specify the input format and device then ffmpeg can grab video and
audio directly.
ffmpeg -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
Or with an ALSA audio source (mono input, card id 1) instead of OSS:
ffmpeg -f alsa -ac 1 -i hw:1 -f video4linux2 -i /dev/video0 /tmp/out.mpg
Note that you must activate the right video source and channel before launching
ffmpeg with any TV viewer such as xawtv by Gerd Knorr. You also have to set the
audio recording levels correctly with a standard mixer.
6.2 X11 grabbing
Grab the X11 display with ffmpeg via
ffmpeg -f x11grab -video_size cif -framerate 25
-i :0.0 /tmp/out.mp
0.0 is display.screen number of your X11 server, same as the DISPLAY environment
variable.
ffmpeg -f x11grab -video_size cif -framerate 25 -i :0.0+10,20 /tmp/out.mpg
0.0 is display.screen number of your X11 server, same as the DISPLAY
environment variable. 10 is the x-offset and 20 the y-offset for the grabbing.
6.3 Video and Audio file format conversion
Any supported file format and protocol can serve as input to ffmpeg:
Examples:
- You can use YUV files as input:
ffmpeg -i /tmp/test%d.Y /tmp/out.mpg
It will use the files:
/tmp/test0.Y, /tmp/test0.U, /tmp/test0.V, /tmp/test1.Y
, /tmp/test1.U, /tmp/test1.V, etc...
The Y files use twice the resolution of the U and V files. They are raw files,
without header. They can be generated by all decent video decoders. You must
specify the size of the image with the -s option if ffmpeg cannot guess it.
- You can input from a raw YUV420P file:
ffmpeg -i /tmp/test.yuv /tmp/out.avi
test.yuv is a file containing raw YUV planar data. Each frame is composed of the
Y plane followed by the U and V planes at half vertical and horizontal resolution.
- You can output to a raw YUV420P file:
ffmpeg -i mydivx.avi hugefile.yu
- You can set several input files and output files:
ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
Converts the audio file a.wav and the raw YUV video file a.yuv to MPEG file a.mpg.
- You can also do audio and video conversions at the same time:
ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2
Converts a.wav to MPEG audio at 22050 Hz sample rate.
- You can encode to several formats at the same time and define a mapping
from input stream to output streams:
ffmpeg -i /tmp/a.wav -map 0:a -b:a 64k /tmp/a.mp2
-map 0:a -b:a 128
/tmp/b.mp2
Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits.
’-map file:index’ specifies which input stream is used for each output
stream, in the order of the definition of output streams.
- You can transcode decrypted VOBs:
ffmpeg -i snatch_1.vob -f avi -c:v mpeg4 -b:v 800k -g 300
-bf 2 -c:a libmp3lame -b:a 128k snatch.avi
This is a typical DVD ripping example; the input is a VOB file, the output an
AVI file with MPEG-4 video and MP3 audio. Note that in this command we use
B-frames so the MPEG-4 stream is DivX5 compatible, and GOP size is 300 which
means one intra frame every 10 seconds for 29.97fps input video. Furthermore,
the audio stream is MP3-encoded so you need to enable LAME support by passing
--enable-libmp3lame to configure. The mapping is particularly useful for DVD
transcoding to get the desired audio language.
NOTE: To see the supported input formats, use ffmpeg -demuxers.
- You can extract images from a video, or create a video from many images:
For extracting images from a video:
ffmpeg -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpe
This will extract one video frame per second from the video and will output
them in files named foo-001.jpeg, foo-002.jpeg, etc. Images will be rescaled to
fit the new WxH values.
If you want to extract just a limited number of frames, you can use the above
command in combination with the -frames:v or -t option, or in combination
with -ss to start extracting from a certain point in time.
For creating a video from many images:
ffmpeg -f image2 -framerate 12 -i foo-%03d.jpeg -s WxH foo.av
The syntax foo-%03d.jpeg specifies to use a decimal number composed of three
digits padded with zeroes to express the sequence number. It is the same syntax
supported by the C printf function, but only formats accepting a normal integer
are suitable.
When importing an image sequence, -i also supports expanding shell-like wildcard
patterns (globbing) internally, by selecting the image2-specific
-pattern_type glob option.
For example, for creating a video from filenames matching the glob pattern
foo-*.jpeg:
ffmpeg -f image2 -pattern_type glob -framerate 12
-i 'foo-*.jpeg' -s WxH foo.avi
- You can put many streams of the same type in the output:
ffmpeg -i test1.avi -i test2.avi -map 1:1 -map 1:0
-map 0:1 -map 0:0 -c copy -y test12.nut
The resulting output file test12.nut will contain the first four streams
from the input files in reverse order.
- To force CBR video output:
ffmpeg -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v
- The four options lmin, lmax, mblmin and mblmax use ’lambda’ units, but you
may use the QP2LAMBDA constant to easily convert from ’q’ units:
ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext
7 See Also
8 Authors