ffmpeg Documentation

Table of Contents

1 Synopsis

ffmpeg [global_options] {[input_file_options] -i input_url} ... {[output_file_options] output_url} ...

2 Description

ffmpeg is a very fast video and audio converter that can also grab from a live audio/video source. It can also convert between arbitrary sample rates and resize video on the fly with a high quality polyphase filter.

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.

• To set the video bitrate of the output file to 64 kbit/s:

  ffmpeg -i input.avi -b:v 64k -bufsize 64k output.avi
  

• To force the frame rate of the output file to 24 fps:

  ffmpeg -i input.avi -r 24 output.avi
  

• To 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.avi
  

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 automatic stream 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 Time duration 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, duplicate or drop input frames to achieve constant output frame rate fps.

-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.

-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 SwScaler flags.

-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.

-ilme

Force interlacing support in encoder (MPEG-2 and MPEG-4 only). Use this option if your input file is interlaced and you want to keep the interlaced format for minimum losses. The alternative is to deinterlace the input stream by use of a filter such as yadif or bwdif, but deinterlacing introduces losses.

-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.

-vstats_file file

Dump video coding statistics to file.

-vstats_version file

Specifies which version of the vstats format to use. Default is 2.

version = 1 :

frame= %5d q= %2.1f PSNR= %6.2f f_size= %6d s_size= %8.0fkB time= %0.3f br= %7.1fkbits/s avg_br= %7.1fkbits/s

version > 1:

out= %2d st= %2d frame= %5d q= %2.1f PSNR= %6.2f f_size= %6d s_size= %8.0fkB time= %0.3f br= %7.1fkbits/s avg_br= %7.1fkbits/s

-top[:stream_specifier] n (output,per-stream)

top=1/bottom=0/auto=-1 field first

-dc precision

Intra_dc_precision.

-vtag fourcc/tag (output)

Force video tag/fourcc. This is an alias for -tag:v.

-qphist (global)

Show QP histogram

-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_drop

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:1

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 or a DRM render node. If not specified, it will attempt to open the default X11 display ($DISPLAY) and then the first DRM render node (/dev/dri/renderD128).

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.

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 size

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 some input file (specified with -i), the second takes an output from some complex 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.wav

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_unknown

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 OUTPUT

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.

-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.

-async samples_per_second

Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps, the parameter is the maximum samples per second by which the audio is changed. -async 1 is a special case where only the start of the audio stream is corrected without any later correction.

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.

This option has been deprecated. Use the aresample audio filter instead.

-adrift_threshold time

Set the minimum difference between timestamps and audio data (in seconds) to trigger adding/dropping samples to make it match the timestamps. This option effectively is a threshold to select between hard (add/drop) and soft (squeeze/stretch) compensation. -async must be set to a positive value.

-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_zero

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 is a floating point number, and 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.

-1

Use the input stream timebase when possible.

If an input stream is not available, the default timebase will be used.

>0

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 floating point 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

Timestamp discontinuity delta threshold.

-dts_error_threshold seconds

Timestamp error delta threshold. This threshold use to discard crazy/damaged timestamps and the default is 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.ts

-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.h264

ffmpeg -i file.mov -an -vn -bsf:s mov2textsub -c:s copy -f rawvideo sub.txt

-tag[:stream_specifier] codec_tag (input/output,per-stream)

Force a tag/fourcc for matching streams.

-timecode hh:mm:ssSEPff

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.

none

Discard no frame.

default

Default, which discards no frames.

noref

Discard all non-reference frames.

bidir

Discard all bidirectional frames.

nokey

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.

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.

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.mpg

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.yuv
  

• 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 128k /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.jpeg
  

  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.avi
  

  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 Syntax

This section documents the syntax and formats employed by the FFmpeg libraries and tools.

7.1 Quoting and escaping

FFmpeg adopts the following quoting and escaping mechanism, unless explicitly specified. The following rules are applied:

• ‘'’ and ‘\’ are special characters (respectively used for quoting and escaping). In addition to them, there might be other special characters depending on the specific syntax where the escaping and quoting are employed.
• A special character is escaped by prefixing it with a ‘\’.
• All characters enclosed between ‘''’ are included literally in the parsed string. The quote character ‘'’ itself cannot be quoted, so you may need to close the quote and escape it.
• Leading and trailing whitespaces, unless escaped or quoted, are removed from the parsed string.

Note that you may need to add a second level of escaping when using the command line or a script, which depends on the syntax of the adopted shell language.

The function av_get_token defined in libavutil/avstring.h can be used to parse a token quoted or escaped according to the rules defined above.

The tool tools/ffescape in the FFmpeg source tree can be used to automatically quote or escape a string in a script.

7.1.1 Examples

• Escape the string Crime d'Amour containing the ' special character:

  Crime d\'Amour
  

• The string above contains a quote, so the ' needs to be escaped when quoting it:

  'Crime d'\''Amour'
  

• Include leading or trailing whitespaces using quoting:

  '  this string starts and ends with whitespaces  '
  

• Escaping and quoting can be mixed together:

  ' The string '\'string\'' is a string '
  

• To include a literal ‘\’ you can use either escaping or quoting:

  'c:\foo' can be written as c:\\foo
  

7.2 Date

The accepted syntax is:

[(YYYY-MM-DD|YYYYMMDD)[T|t| ]]((HH:MM:SS[.m...]]])|(HHMMSS[.m...]]]))[Z]
now

If the value is "now" it takes the current time.

Time is local time unless Z is appended, in which case it is interpreted as UTC. If the year-month-day part is not specified it takes the current year-month-day.

7.3 Time duration

There are two accepted syntaxes for expressing time duration.

[-][HH:]MM:SS[.m...]

HH expresses the number of hours, MM the number of minutes for a maximum of 2 digits, and SS the number of seconds for a maximum of 2 digits. The m at the end expresses decimal value for SS.

or

[-]S+[.m...][s|ms|us]

S expresses the number of seconds, with the optional decimal part m. The optional literal suffixes ‘s’, ‘ms’ or ‘us’ indicate to interpret the value as seconds, milliseconds or microseconds, respectively.

In both expressions, the optional ‘-’ indicates negative duration.

7.3.1 Examples

The following examples are all valid time duration:

‘55’

55 seconds

‘0.2’

0.2 seconds

‘200ms’

200 milliseconds, that’s 0.2s

‘200000us’

200000 microseconds, that’s 0.2s

‘12:03:45’

12 hours, 03 minutes and 45 seconds

‘23.189’

23.189 seconds

7.4 Video size

Specify the size of the sourced video, it may be a string of the form widthxheight, or the name of a size abbreviation.

The following abbreviations are recognized:

‘ntsc’

720x480

‘pal’

720x576

‘qntsc’

352x240

‘qpal’

352x288

‘sntsc’

640x480

‘spal’

768x576

‘film’

352x240

‘ntsc-film’

352x240

‘sqcif’

128x96

‘qcif’

176x144

‘cif’

352x288

‘4cif’

704x576

‘16cif’

1408x1152

‘qqvga’

160x120

‘qvga’

320x240

‘vga’

640x480

‘svga’

800x600

‘xga’

1024x768

‘uxga’

1600x1200

‘qxga’

2048x1536

‘sxga’

1280x1024

‘qsxga’

2560x2048

‘hsxga’

5120x4096

‘wvga’

852x480

‘wxga’

1366x768

‘wsxga’

1600x1024

‘wuxga’

1920x1200

‘woxga’

2560x1600

‘wqsxga’

3200x2048

‘wquxga’

3840x2400

‘whsxga’

6400x4096

‘whuxga’

7680x4800

‘cga’

320x200

‘ega’

640x350

‘hd480’

852x480

‘hd720’

1280x720

‘hd1080’

1920x1080

‘2k’

2048x1080

‘2kflat’

1998x1080

‘2kscope’

2048x858

‘4k’

4096x2160

‘4kflat’

3996x2160

‘4kscope’

4096x1716

‘nhd’

640x360

‘hqvga’

240x160

‘wqvga’

400x240

‘fwqvga’

432x240

‘hvga’

480x320

‘qhd’

960x540

‘2kdci’

2048x1080

‘4kdci’

4096x2160

‘uhd2160’

3840x2160

‘uhd4320’

7680x4320

7.5 Video rate

Specify the frame rate of a video, expressed as the number of frames generated per second. It has to be a string in the format frame_rate_num/frame_rate_den, an integer number, a float number or a valid video frame rate abbreviation.

The following abbreviations are recognized:

‘ntsc’

30000/1001

‘pal’

25/1

‘qntsc’

30000/1001

‘qpal’

25/1

‘sntsc’

30000/1001

‘spal’

25/1

‘film’

24/1

‘ntsc-film’

24000/1001

7.6 Ratio

A ratio can be expressed as an expression, or in the form numerator:denominator.

Note that a ratio with infinite (1/0) or negative value is considered valid, so you should check on the returned value if you want to exclude those values.

The undefined value can be expressed using the "0:0" string.

7.7 Color

It can be the name of a color as defined below (case insensitive match) or a [0x|#]RRGGBB[AA] sequence, possibly followed by @ and a string representing the alpha component.

The alpha component may be a string composed by "0x" followed by an hexadecimal number or a decimal number between 0.0 and 1.0, which represents the opacity value (‘0x00’ or ‘0.0’ means completely transparent, ‘0xff’ or ‘1.0’ completely opaque). If the alpha component is not specified then ‘0xff’ is assumed.

The string ‘random’ will result in a random color.

The following names of colors are recognized:

‘AliceBlue’

0xF0F8FF

‘AntiqueWhite’

0xFAEBD7

‘Aqua’

0x00FFFF

‘Aquamarine’

0x7FFFD4

‘Azure’

0xF0FFFF

‘Beige’

0xF5F5DC

‘Bisque’

0xFFE4C4

‘Black’

0x000000

‘BlanchedAlmond’

0xFFEBCD

‘Blue’

0x0000FF

‘BlueViolet’

0x8A2BE2

‘Brown’

0xA52A2A

‘BurlyWood’

0xDEB887

‘CadetBlue’

0x5F9EA0

‘Chartreuse’

0x7FFF00

‘Chocolate’

0xD2691E

‘Coral’

0xFF7F50

‘CornflowerBlue’

0x6495ED

‘Cornsilk’

0xFFF8DC

‘Crimson’

0xDC143C

‘Cyan’

0x00FFFF

‘DarkBlue’

0x00008B

‘DarkCyan’

0x008B8B

‘DarkGoldenRod’

0xB8860B

‘DarkGray’

0xA9A9A9

‘DarkGreen’

0x006400

‘DarkKhaki’

0xBDB76B

‘DarkMagenta’

0x8B008B

‘DarkOliveGreen’

0x556B2F

‘Darkorange’

0xFF8C00

‘DarkOrchid’

0x9932CC

‘DarkRed’

0x8B0000

‘DarkSalmon’

0xE9967A

‘DarkSeaGreen’

0x8FBC8F

‘DarkSlateBlue’

0x483D8B

‘DarkSlateGray’

0x2F4F4F

‘DarkTurquoise’

0x00CED1

‘DarkViolet’

0x9400D3

‘DeepPink’

0xFF1493

‘DeepSkyBlue’

0x00BFFF

‘DimGray’

0x696969

‘DodgerBlue’

0x1E90FF

‘FireBrick’

0xB22222

‘FloralWhite’

0xFFFAF0

‘ForestGreen’

0x228B22

‘Fuchsia’

0xFF00FF

‘Gainsboro’

0xDCDCDC

‘GhostWhite’

0xF8F8FF

‘Gold’

0xFFD700

‘GoldenRod’

0xDAA520

‘Gray’

0x808080

‘Green’

0x008000

‘GreenYellow’

0xADFF2F

‘HoneyDew’

0xF0FFF0

‘HotPink’

0xFF69B4

‘IndianRed’

0xCD5C5C

‘Indigo’

0x4B0082

‘Ivory’

0xFFFFF0

‘Khaki’

0xF0E68C

‘Lavender’

0xE6E6FA

‘LavenderBlush’

0xFFF0F5

‘LawnGreen’

0x7CFC00

‘LemonChiffon’

0xFFFACD

‘LightBlue’

0xADD8E6

‘LightCoral’

0xF08080

‘LightCyan’

0xE0FFFF

‘LightGoldenRodYellow’

0xFAFAD2

‘LightGreen’

0x90EE90

‘LightGrey’

0xD3D3D3

‘LightPink’

0xFFB6C1

‘LightSalmon’

0xFFA07A

‘LightSeaGreen’

0x20B2AA

‘LightSkyBlue’

0x87CEFA

‘LightSlateGray’

0x778899

‘LightSteelBlue’

0xB0C4DE

‘LightYellow’

0xFFFFE0

‘Lime’

0x00FF00

‘LimeGreen’

0x32CD32

‘Linen’

0xFAF0E6

‘Magenta’

0xFF00FF

‘Maroon’

0x800000

‘MediumAquaMarine’

0x66CDAA

‘MediumBlue’

0x0000CD

‘MediumOrchid’

0xBA55D3

‘MediumPurple’

0x9370D8

‘MediumSeaGreen’

0x3CB371

‘MediumSlateBlue’

0x7B68EE

‘MediumSpringGreen’

0x00FA9A

‘MediumTurquoise’

0x48D1CC

‘MediumVioletRed’

0xC71585

‘MidnightBlue’

0x191970

‘MintCream’

0xF5FFFA

‘MistyRose’

0xFFE4E1

‘Moccasin’

0xFFE4B5

‘NavajoWhite’

0xFFDEAD

‘Navy’

0x000080

‘OldLace’

0xFDF5E6

‘Olive’

0x808000

‘OliveDrab’

0x6B8E23

‘Orange’

0xFFA500

‘OrangeRed’

0xFF4500

‘Orchid’

0xDA70D6

‘PaleGoldenRod’

0xEEE8AA

‘PaleGreen’

0x98FB98

‘PaleTurquoise’

0xAFEEEE

‘PaleVioletRed’

0xD87093

‘PapayaWhip’

0xFFEFD5

‘PeachPuff’

0xFFDAB9

‘Peru’

0xCD853F

‘Pink’

0xFFC0CB

‘Plum’

0xDDA0DD

‘PowderBlue’

0xB0E0E6

‘Purple’

0x800080

‘Red’

0xFF0000

‘RosyBrown’

0xBC8F8F

‘RoyalBlue’

0x4169E1

‘SaddleBrown’

0x8B4513

‘Salmon’

0xFA8072

‘SandyBrown’

0xF4A460

‘SeaGreen’

0x2E8B57

‘SeaShell’

0xFFF5EE

‘Sienna’

0xA0522D

‘Silver’

0xC0C0C0

‘SkyBlue’

0x87CEEB

‘SlateBlue’

0x6A5ACD

‘SlateGray’

0x708090

‘Snow’

0xFFFAFA

‘SpringGreen’

0x00FF7F

‘SteelBlue’

0x4682B4

‘Tan’

0xD2B48C

‘Teal’

0x008080

‘Thistle’

0xD8BFD8

‘Tomato’

0xFF6347

‘Turquoise’

0x40E0D0

‘Violet’

0xEE82EE

‘Wheat’

0xF5DEB3

‘White’

0xFFFFFF

‘WhiteSmoke’

0xF5F5F5

‘Yellow’

0xFFFF00

‘YellowGreen’

0x9ACD32

7.8 Channel Layout

A channel layout specifies the spatial disposition of the channels in a multi-channel audio stream. To specify a channel layout, FFmpeg makes use of a special syntax.

Individual channels are identified by an id, as given by the table below:

‘FL’

front left

‘FR’

front right

‘FC’

front center

‘LFE’

low frequency

‘BL’

back left

‘BR’

back right

‘FLC’

front left-of-center

‘FRC’

front right-of-center

‘BC’

back center

‘SL’

side left

‘SR’

side right

‘TC’

top center

‘TFL’

top front left

‘TFC’

top front center

‘TFR’

top front right

‘TBL’

top back left

‘TBC’

top back center

‘TBR’

top back right

‘DL’

downmix left

‘DR’

downmix right

‘WL’

wide left

‘WR’

wide right

‘SDL’

surround direct left

‘SDR’

surround direct right

‘LFE2’

low frequency 2

Standard channel layout compositions can be specified by using the following identifiers:

‘mono’

FC

‘stereo’

FL+FR

‘2.1’

FL+FR+LFE

‘3.0’

FL+FR+FC

‘3.0(back)’

FL+FR+BC

‘4.0’

FL+FR+FC+BC

‘quad’

FL+FR+BL+BR

‘quad(side)’

FL+FR+SL+SR

‘3.1’

FL+FR+FC+LFE

‘5.0’

FL+FR+FC+BL+BR

‘5.0(side)’

FL+FR+FC+SL+SR

‘4.1’

FL+FR+FC+LFE+BC

‘5.1’

FL+FR+FC+LFE+BL+BR

‘5.1(side)’

FL+FR+FC+LFE+SL+SR

‘6.0’

FL+FR+FC+BC+SL+SR

‘6.0(front)’

FL+FR+FLC+FRC+SL+SR

‘hexagonal’

FL+FR+FC+BL+BR+BC

‘6.1’

FL+FR+FC+LFE+BC+SL+SR

‘6.1’

FL+FR+FC+LFE+BL+BR+BC

‘6.1(front)’

FL+FR+LFE+FLC+FRC+SL+SR

‘7.0’

FL+FR+FC+BL+BR+SL+SR

‘7.0(front)’

FL+FR+FC+FLC+FRC+SL+SR

‘7.1’

FL+FR+FC+LFE+BL+BR+SL+SR

‘7.1(wide)’

FL+FR+FC+LFE+BL+BR+FLC+FRC

‘7.1(wide-side)’

FL+FR+FC+LFE+FLC+FRC+SL+SR

‘octagonal’

FL+FR+FC+BL+BR+BC+SL+SR

‘hexadecagonal’

FL+FR+FC+BL+BR+BC+SL+SR+WL+WR+TBL+TBR+TBC+TFC+TFL+TFR

‘downmix’

DL+DR

‘22.2’

FL+FR+FC+LFE+BL+BR+FLC+FRC+BC+SL+SR+TC+TFL+TFC+TFR+TBL+TBC+TBR+LFE2+TSL+TSR+BFC+BFL+BFR

A custom channel layout can be specified as a sequence of terms, separated by ’+’. Each term can be:

• the name of a single channel (e.g. ‘FL’, ‘FR’, ‘FC’, ‘LFE’, etc.), each optionally containing a custom name after a ’@’, (e.g. ‘FL@Left’, ‘FR@Right’, ‘FC@Center’, ‘LFE@Low_Frequency’, etc.)

A standard channel layout can be specified by the following:

• the name of a single channel (e.g. ‘FL’, ‘FR’, ‘FC’, ‘LFE’, etc.)
• the name of a standard channel layout (e.g. ‘mono’, ‘stereo’, ‘4.0’, ‘quad’, ‘5.0’, etc.)
• a number of channels, in decimal, followed by ’c’, yielding the default channel layout for that number of channels (see the function av_channel_layout_default). Note that not all channel counts have a default layout.
• a number of channels, in decimal, followed by ’C’, yielding an unknown channel layout with the specified number of channels. Note that not all channel layout specification strings support unknown channel layouts.
• a channel layout mask, in hexadecimal starting with "0x" (see the AV_CH_* macros in libavutil/channel_layout.h.

Before libavutil version 53 the trailing character "c" to specify a number of channels was optional, but now it is required, while a channel layout mask can also be specified as a decimal number (if and only if not followed by "c" or "C").

See also the function av_channel_layout_from_string defined in libavutil/channel_layout.h.

8 Expression Evaluation

When evaluating an arithmetic expression, FFmpeg uses an internal formula evaluator, implemented through the libavutil/eval.h interface.

An expression may contain unary, binary operators, constants, and functions.

Two expressions expr1 and expr2 can be combined to form another expression "expr1;expr2". expr1 and expr2 are evaluated in turn, and the new expression evaluates to the value of expr2.

The following binary operators are available: +, -, *, /, ^.

The following unary operators are available: +, -.

The following functions are available:

abs(x)

Compute absolute value of x.

acos(x)

Compute arccosine of x.

asin(x)

Compute arcsine of x.

atan(x)

Compute arctangent of x.

atan2(x, y)

Compute principal value of the arc tangent of y/x.

between(x, min, max)

Return 1 if x is greater than or equal to min and lesser than or equal to max, 0 otherwise.

bitand(x, y)

bitor(x, y)

Compute bitwise and/or operation on x and y.

The results of the evaluation of x and y are converted to integers before executing the bitwise operation.

Note that both the conversion to integer and the conversion back to floating point can lose precision. Beware of unexpected results for large numbers (usually 2^53 and larger).

ceil(expr)

Round the value of expression expr upwards to the nearest integer. For example, "ceil(1.5)" is "2.0".

clip(x, min, max)

Return the value of x clipped between min and max.

cos(x)

Compute cosine of x.

cosh(x)

Compute hyperbolic cosine of x.

eq(x, y)

Return 1 if x and y are equivalent, 0 otherwise.

exp(x)

Compute exponential of x (with base e, the Euler’s number).

floor(expr)

Round the value of expression expr downwards to the nearest integer. For example, "floor(-1.5)" is "-2.0".

gauss(x)

Compute Gauss function of x, corresponding to exp(-x*x/2) / sqrt(2*PI).

gcd(x, y)

Return the greatest common divisor of x and y. If both x and y are 0 or either or both are less than zero then behavior is undefined.

gt(x, y)

Return 1 if x is greater than y, 0 otherwise.

gte(x, y)

Return 1 if x is greater than or equal to y, 0 otherwise.

hypot(x, y)

This function is similar to the C function with the same name; it returns "sqrt(x*x + y*y)", the length of the hypotenuse of a right triangle with sides of length x and y, or the distance of the point (x, y) from the origin.

if(x, y)

Evaluate x, and if the result is non-zero return the result of the evaluation of y, return 0 otherwise.

if(x, y, z)

Evaluate x, and if the result is non-zero return the evaluation result of y, otherwise the evaluation result of z.

ifnot(x, y)

Evaluate x, and if the result is zero return the result of the evaluation of y, return 0 otherwise.

ifnot(x, y, z)

Evaluate x, and if the result is zero return the evaluation result of y, otherwise the evaluation result of z.

isinf(x)

Return 1.0 if x is +/-INFINITY, 0.0 otherwise.

isnan(x)

Return 1.0 if x is NAN, 0.0 otherwise.

ld(var)

Load the value of the internal variable with number var, which was previously stored with st(var, expr). The function returns the loaded value.

lerp(x, y, z)

Return linear interpolation between x and y by amount of z.

log(x)

Compute natural logarithm of x.

lt(x, y)

Return 1 if x is lesser than y, 0 otherwise.

lte(x, y)

Return 1 if x is lesser than or equal to y, 0 otherwise.

max(x, y)

Return the maximum between x and y.

min(x, y)

Return the minimum between x and y.

mod(x, y)

Compute the remainder of division of x by y.

not(expr)

Return 1.0 if expr is zero, 0.0 otherwise.

pow(x, y)

Compute the power of x elevated y, it is equivalent to "(x)^(y)".

print(t)

print(t, l)

Print the value of expression t with loglevel l. If l is not specified then a default log level is used. Returns the value of the expression printed.

Prints t with loglevel l

random(x)

Return a pseudo random value between 0.0 and 1.0. x is the index of the internal variable which will be used to save the seed/state.

root(expr, max)

Find an input value for which the function represented by expr with argument ld(0) is 0 in the interval 0..max.

The expression in expr must denote a continuous function or the result is undefined.

ld(0) is used to represent the function input value, which means that the given expression will be evaluated multiple times with various input values that the expression can access through ld(0). When the expression evaluates to 0 then the corresponding input value will be returned.

round(expr)

Round the value of expression expr to the nearest integer. For example, "round(1.5)" is "2.0".

sgn(x)

Compute sign of x.

sin(x)

Compute sine of x.

sinh(x)

Compute hyperbolic sine of x.

sqrt(expr)

Compute the square root of expr. This is equivalent to "(expr)^.5".

squish(x)

Compute expression 1/(1 + exp(4*x)).

st(var, expr)

Store the value of the expression expr in an internal variable. var specifies the number of the variable where to store the value, and it is a value ranging from 0 to 9. The function returns the value stored in the internal variable. Note, Variables are currently not shared between expressions.

tan(x)

Compute tangent of x.

tanh(x)

Compute hyperbolic tangent of x.

taylor(expr, x)

taylor(expr, x, id)

Evaluate a Taylor series at x, given an expression representing the ld(id)-th derivative of a function at 0.

When the series does not converge the result is undefined.

ld(id) is used to represent the derivative order in expr, which means that the given expression will be evaluated multiple times with various input values that the expression can access through ld(id). If id is not specified then 0 is assumed.

Note, when you have the derivatives at y instead of 0, taylor(expr, x-y) can be used.

time(0)

Return the current (wallclock) time in seconds.

trunc(expr)

Round the value of expression expr towards zero to the nearest integer. For example, "trunc(-1.5)" is "-1.0".

while(cond, expr)

Evaluate expression expr while the expression cond is non-zero, and returns the value of the last expr evaluation, or NAN if cond was always false.

The following constants are available:

PI

area of the unit disc, approximately 3.14

E

exp(1) (Euler’s number), approximately 2.718

PHI

golden ratio (1+sqrt(5))/2, approximately 1.618

Assuming that an expression is considered "true" if it has a non-zero value, note that:

* works like AND

+ works like OR

For example the construct:

if (A AND B) then C

is equivalent to:

if(A*B, C)

In your C code, you can extend the list of unary and binary functions, and define recognized constants, so that they are available for your expressions.

The evaluator also recognizes the International System unit prefixes. If ’i’ is appended after the prefix, binary prefixes are used, which are based on powers of 1024 instead of powers of 1000. The ’B’ postfix multiplies the value by 8, and can be appended after a unit prefix or used alone. This allows using for example ’KB’, ’MiB’, ’G’ and ’B’ as number postfix.

The list of available International System prefixes follows, with indication of the corresponding powers of 10 and of 2.

y

10^-24 / 2^-80

z

10^-21 / 2^-70

a

10^-18 / 2^-60

f

10^-15 / 2^-50

p

10^-12 / 2^-40

n

10^-9 / 2^-30

u

10^-6 / 2^-20

m

10^-3 / 2^-10

c

10^-2

d

10^-1

h

10^2

k

10^3 / 2^10

K

10^3 / 2^10

M

10^6 / 2^20

G

10^9 / 2^30

T

10^12 / 2^40

P

10^15 / 2^50

E

10^18 / 2^60

Z

10^21 / 2^70

Y

10^24 / 2^80

9 Codec Options

libavcodec provides some generic global options, which can be set on all the encoders and decoders. In addition each codec may support so-called private options, which are specific for a given codec.

Sometimes, a global option may only affect a specific kind of codec, and may be nonsensical or ignored by another, so you need to be aware of the meaning of the specified options. Also some options are meant only for decoding or encoding.

Options may be set by specifying -option value in the FFmpeg tools, or by setting the value explicitly in the AVCodecContext options or using the libavutil/opt.h API for programmatic use.

The list of supported options follow:

b integer (encoding,audio,video)

Set bitrate in bits/s. Default value is 200K.

ab integer (encoding,audio)

Set audio bitrate (in bits/s). Default value is 128K.

bt integer (encoding,video)

Set video bitrate tolerance (in bits/s). In 1-pass mode, bitrate tolerance specifies how far ratecontrol is willing to deviate from the target average bitrate value. This is not related to min/max bitrate. Lowering tolerance too much has an adverse effect on quality.

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

Set generic flags.

Possible values:

‘mv4’

Use four motion vector by macroblock (mpeg4).

‘qpel’

Use 1/4 pel motion compensation.

‘loop’

Use loop filter.

‘qscale’

Use fixed qscale.

‘pass1’

Use internal 2pass ratecontrol in first pass mode.

‘pass2’

Use internal 2pass ratecontrol in second pass mode.

‘gray’

Only decode/encode grayscale.

‘psnr’

Set error[?] variables during encoding.

‘truncated’

Input bitstream might be randomly truncated.

‘drop_changed’

Don’t output frames whose parameters differ from first decoded frame in stream. Error AVERROR_INPUT_CHANGED is returned when a frame is dropped.

‘ildct’

Use interlaced DCT.

‘low_delay’

Force low delay.

‘global_header’

Place global headers in extradata instead of every keyframe.

‘bitexact’

Only write platform-, build- and time-independent data. (except (I)DCT). This ensures that file and data checksums are reproducible and match between platforms. Its primary use is for regression testing.

‘aic’

Apply H263 advanced intra coding / mpeg4 ac prediction.

‘ilme’

Apply interlaced motion estimation.

‘cgop’

Use closed gop.

‘output_corrupt’

Output even potentially corrupted frames.

time_base rational number

Set codec time base.

It is the fundamental unit of time (in seconds) in terms of which frame timestamps are represented. For fixed-fps content, timebase should be 1 / frame_rate and timestamp increments should be identically 1.

g integer (encoding,video)

Set the group of picture (GOP) size. Default value is 12.

ar integer (decoding/encoding,audio)

Set audio sampling rate (in Hz).

ac integer (decoding/encoding,audio)

Set number of audio channels.

cutoff integer (encoding,audio)

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

frame_size integer (encoding,audio)

Set audio frame size.

Each submitted frame except the last must contain exactly frame_size samples per channel. May be 0 when the codec has CODEC_CAP_VARIABLE_FRAME_SIZE set, in that case the frame size is not restricted. It is set by some decoders to indicate constant frame size.

frame_number integer

Set the frame number.

delay integer

qcomp float (encoding,video)

Set video quantizer scale compression (VBR). It is used as a constant in the ratecontrol equation. Recommended range for default rc_eq: 0.0-1.0.

qblur float (encoding,video)

Set video quantizer scale blur (VBR).

qmin integer (encoding,video)

Set min video quantizer scale (VBR). Must be included between -1 and 69, default value is 2.

qmax integer (encoding,video)

Set max video quantizer scale (VBR). Must be included between -1 and 1024, default value is 31.

qdiff integer (encoding,video)

Set max difference between the quantizer scale (VBR).

bf integer (encoding,video)

Set max number of B frames between non-B-frames.

Must be an integer between -1 and 16. 0 means that B-frames are disabled. If a value of -1 is used, it will choose an automatic value depending on the encoder.

Default value is 0.

b_qfactor float (encoding,video)

Set qp factor between P and B frames.

codec_tag integer

bug flags (decoding,video)

Workaround not auto detected encoder bugs.

Possible values:

‘autodetect’

‘xvid_ilace’

Xvid interlacing bug (autodetected if fourcc==XVIX)

‘ump4’

(autodetected if fourcc==UMP4)

‘no_padding’

padding bug (autodetected)

‘amv’

‘qpel_chroma’

‘std_qpel’

old standard qpel (autodetected per fourcc/version)

‘qpel_chroma2’

‘direct_blocksize’

direct-qpel-blocksize bug (autodetected per fourcc/version)

‘edge’

edge padding bug (autodetected per fourcc/version)

‘hpel_chroma’

‘dc_clip’

‘ms’

Workaround various bugs in microsoft broken decoders.

‘trunc’

trancated frames

strict integer (decoding/encoding,audio,video)

Specify how strictly to follow the standards.

Possible values:

‘very’

strictly conform to an older more strict version of the spec or reference software

‘strict’

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

‘normal’

‘unofficial’

allow unofficial extensions

‘experimental’

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

b_qoffset float (encoding,video)

Set QP offset between P and B frames.

err_detect flags (decoding,audio,video)

Set error detection flags.

Possible values:

‘crccheck’

verify embedded CRCs

‘bitstream’

detect bitstream specification deviations

‘buffer’

detect improper bitstream length

‘explode’

abort decoding on minor error detection

‘ignore_err’

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

‘careful’

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

‘compliant’

consider all spec non compliancies as errors

‘aggressive’

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

has_b_frames integer

block_align integer

rc_override_count integer

maxrate integer (encoding,audio,video)

Set max bitrate tolerance (in bits/s). Requires bufsize to be set.

minrate integer (encoding,audio,video)

Set min bitrate tolerance (in bits/s). Most useful in setting up a CBR encode. It is of little use elsewise.

bufsize integer (encoding,audio,video)

Set ratecontrol buffer size (in bits).

i_qfactor float (encoding,video)

Set QP factor between P and I frames.

i_qoffset float (encoding,video)

Set QP offset between P and I frames.

dct integer (encoding,video)

Set DCT algorithm.

Possible values:

‘auto’

autoselect a good one (default)

‘fastint’

fast integer

‘int’

accurate integer

‘mmx’

‘altivec’

‘faan’

floating point AAN DCT

lumi_mask float (encoding,video)

Compress bright areas stronger than medium ones.

tcplx_mask float (encoding,video)

Set temporal complexity masking.

scplx_mask float (encoding,video)

Set spatial complexity masking.

p_mask float (encoding,video)

Set inter masking.

dark_mask float (encoding,video)

Compress dark areas stronger than medium ones.

idct integer (decoding/encoding,video)

Select IDCT implementation.

Possible values:

‘auto’

‘int’

‘simple’

‘simplemmx’

‘simpleauto’

Automatically pick a IDCT compatible with the simple one

‘arm’

‘altivec’

‘sh4’

‘simplearm’

‘simplearmv5te’

‘simplearmv6’

‘simpleneon’

‘xvid’

‘faani’

floating point AAN IDCT

slice_count integer

ec flags (decoding,video)

Set error concealment strategy.

Possible values:

‘guess_mvs’

iterative motion vector (MV) search (slow)

‘deblock’

use strong deblock filter for damaged MBs

‘favor_inter’

favor predicting from the previous frame instead of the current

bits_per_coded_sample integer

aspect rational number (encoding,video)

Set sample aspect ratio.

sar rational number (encoding,video)

Set sample aspect ratio. Alias to aspect.

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

Print specific debug info.

Possible values:

‘pict’

picture info

‘rc’

rate control

‘bitstream’

‘mb_type’

macroblock (MB) type

‘qp’

per-block quantization parameter (QP)

‘dct_coeff’

‘green_metadata’

display complexity metadata for the upcoming frame, GoP or for a given duration.

‘skip’

‘startcode’

‘er’

error recognition

‘mmco’

memory management control operations (H.264)

‘bugs’

‘buffers’

picture buffer allocations

‘thread_ops’

threading operations

‘nomc’

skip motion compensation

cmp integer (encoding,video)

Set full pel me compare function.

Possible values:

‘sad’

sum of absolute differences, fast (default)

‘sse’

sum of squared errors

‘satd’

sum of absolute Hadamard transformed differences

‘dct’

sum of absolute DCT transformed differences

‘psnr’

sum of squared quantization errors (avoid, low quality)

‘bit’

number of bits needed for the block

‘rd’

rate distortion optimal, slow

‘zero’

0

‘vsad’

sum of absolute vertical differences

‘vsse’

sum of squared vertical differences

‘nsse’

noise preserving sum of squared differences

‘w53’

5/3 wavelet, only used in snow

‘w97’

9/7 wavelet, only used in snow

‘dctmax’

‘chroma’

subcmp integer (encoding,video)

Set sub pel me compare function.

Possible values:

‘sad’

sum of absolute differences, fast (default)

‘sse’

sum of squared errors

‘satd’

sum of absolute Hadamard transformed differences

‘dct’

sum of absolute DCT transformed differences

‘psnr’

sum of squared quantization errors (avoid, low quality)

‘bit’

number of bits needed for the block

‘rd’

rate distortion optimal, slow

‘zero’

0

‘vsad’

sum of absolute vertical differences

‘vsse’

sum of squared vertical differences

‘nsse’

noise preserving sum of squared differences

‘w53’

5/3 wavelet, only used in snow

‘w97’

9/7 wavelet, only used in snow

‘dctmax’

‘chroma’

mbcmp integer (encoding,video)

Set macroblock compare function.

Possible values:

‘sad’

sum of absolute differences, fast (default)

‘sse’

sum of squared errors

‘satd’

sum of absolute Hadamard transformed differences

‘dct’

sum of absolute DCT transformed differences

‘psnr’

sum of squared quantization errors (avoid, low quality)

‘bit’

number of bits needed for the block

‘rd’

rate distortion optimal, slow

‘zero’

0

‘vsad’

sum of absolute vertical differences

‘vsse’

sum of squared vertical differences

‘nsse’

noise preserving sum of squared differences

‘w53’

5/3 wavelet, only used in snow

‘w97’

9/7 wavelet, only used in snow

‘dctmax’

‘chroma’

ildctcmp integer (encoding,video)

Set interlaced dct compare function.

Possible values:

‘sad’

sum of absolute differences, fast (default)

‘sse’

sum of squared errors

‘satd’

sum of absolute Hadamard transformed differences

‘dct’

sum of absolute DCT transformed differences

‘psnr’

sum of squared quantization errors (avoid, low quality)

‘bit’

number of bits needed for the block

‘rd’

rate distortion optimal, slow

‘zero’

0

‘vsad’

sum of absolute vertical differences

‘vsse’

sum of squared vertical differences

‘nsse’

noise preserving sum of squared differences

‘w53’

5/3 wavelet, only used in snow

‘w97’

9/7 wavelet, only used in snow

‘dctmax’

‘chroma’

dia_size integer (encoding,video)

Set diamond type & size for motion estimation.

‘(1024, INT_MAX)’

full motion estimation(slowest)

‘(768, 1024]’

umh motion estimation

‘(512, 768]’

hex motion estimation

‘(256, 512]’

l2s diamond motion estimation

‘[2,256]’

var diamond motion estimation

‘(-1, 2)’

small diamond motion estimation

‘-1’

funny diamond motion estimation

‘(INT_MIN, -1)’

sab diamond motion estimation

last_pred integer (encoding,video)

Set amount of motion predictors from the previous frame.

precmp integer (encoding,video)

Set pre motion estimation compare function.

Possible values:

‘sad’

sum of absolute differences, fast (default)

‘sse’

sum of squared errors

‘satd’

sum of absolute Hadamard transformed differences

‘dct’

sum of absolute DCT transformed differences

‘psnr’

sum of squared quantization errors (avoid, low quality)

‘bit’

number of bits needed for the block

‘rd’

rate distortion optimal, slow

‘zero’

0

‘vsad’

sum of absolute vertical differences

‘vsse’

sum of squared vertical differences

‘nsse’

noise preserving sum of squared differences

‘w53’

5/3 wavelet, only used in snow

‘w97’

9/7 wavelet, only used in snow

‘dctmax’

‘chroma’

pre_dia_size integer (encoding,video)

Set diamond type & size for motion estimation pre-pass.

subq integer (encoding,video)

Set sub pel motion estimation quality.

me_range integer (encoding,video)

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

global_quality integer (encoding,audio,video)

slice_flags integer

mbd integer (encoding,video)

Set macroblock decision algorithm (high quality mode).

Possible values:

‘simple’

use mbcmp (default)

‘bits’

use fewest bits

‘rd’

use best rate distortion

rc_init_occupancy integer (encoding,video)

Set number of bits which should be loaded into the rc buffer before decoding starts.

flags2 flags (decoding/encoding,audio,video,subtitles)

Possible values:

‘fast’

Allow non spec compliant speedup tricks.

‘noout’

Skip bitstream encoding.

‘ignorecrop’

Ignore cropping information from sps.

‘local_header’

Place global headers at every keyframe instead of in extradata.

‘chunks’

Frame data might be split into multiple chunks.

‘showall’

Show all frames before the first keyframe.

‘export_mvs’

Export motion vectors into frame side-data (see AV_FRAME_DATA_MOTION_VECTORS) for codecs that support it. See also doc/examples/export_mvs.c.

‘skip_manual’

Do not skip samples and export skip information as frame side data.

‘ass_ro_flush_noop’

Do not reset ASS ReadOrder field on flush.

‘icc_profiles’

Generate/parse embedded ICC profiles from/to colorimetry tags.

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

Possible values:

‘mvs’

Export motion vectors into frame side-data (see AV_FRAME_DATA_MOTION_VECTORS) for codecs that support it. See also doc/examples/export_mvs.c.

‘prft’

Export encoder Producer Reference Time into packet side-data (see AV_PKT_DATA_PRFT) for codecs that support it.

‘venc_params’

Export video encoding parameters through frame side data (see AV_FRAME_DATA_VIDEO_ENC_PARAMS) for codecs that support it. At present, those are H.264 and VP9.

‘film_grain’

Export film grain parameters through frame side data (see AV_FRAME_DATA_FILM_GRAIN_PARAMS). Supported at present by AV1 decoders.

threads integer (decoding/encoding,video)

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

Possible values:

‘auto, 0’

automatically select the number of threads to set

Default value is ‘auto’.

dc integer (encoding,video)

Set intra_dc_precision.

nssew integer (encoding,video)

Set nsse weight.

skip_top integer (decoding,video)

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

skip_bottom integer (decoding,video)

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

profile integer (encoding,audio,video)

Set encoder codec profile. Default value is ‘unknown’. Encoder specific profiles are documented in the relevant encoder documentation.

level integer (encoding,audio,video)

Possible values:

‘unknown’

lowres integer (decoding,audio,video)

Decode at 1= 1/2, 2=1/4, 3=1/8 resolutions.

mblmin integer (encoding,video)

Set min macroblock lagrange factor (VBR).

mblmax integer (encoding,video)

Set max macroblock lagrange factor (VBR).

skip_loop_filter integer (decoding,video)

skip_idct integer (decoding,video)

skip_frame integer (decoding,video)

Make decoder discard processing depending on the frame type selected by the option value.

skip_loop_filter skips frame loop filtering, skip_idct skips frame IDCT/dequantization, skip_frame skips decoding.

Possible values:

‘none’

Discard no frame.

‘default’

Discard useless frames like 0-sized frames.

‘noref’

Discard all non-reference frames.

‘bidir’

Discard all bidirectional frames.

‘nokey’

Discard all frames excepts keyframes.

‘nointra’

Discard all frames except I frames.

‘all’

Discard all frames.

Default value is ‘default’.

bidir_refine integer (encoding,video)

Refine the two motion vectors used in bidirectional macroblocks.

keyint_min integer (encoding,video)

Set minimum interval between IDR-frames.

refs integer (encoding,video)

Set reference frames to consider for motion compensation.

trellis integer (encoding,audio,video)

Set rate-distortion optimal quantization.

mv0_threshold integer (encoding,video)

compression_level integer (encoding,audio,video)

bits_per_raw_sample integer

channel_layout integer (decoding/encoding,audio)

Possible values:

request_channel_layout integer (decoding,audio)

Possible values:

rc_max_vbv_use float (encoding,video)

rc_min_vbv_use float (encoding,video)

ticks_per_frame integer (decoding/encoding,audio,video)

color_primaries integer (decoding/encoding,video)

Possible values:

‘bt709’

BT.709

‘bt470m’

BT.470 M

‘bt470bg’

BT.470 BG

‘smpte170m’

SMPTE 170 M

‘smpte240m’

SMPTE 240 M

‘film’

Film

‘bt2020’

BT.2020

‘smpte428’

‘smpte428_1’

SMPTE ST 428-1

‘smpte431’

SMPTE 431-2

‘smpte432’

SMPTE 432-1

‘jedec-p22’

JEDEC P22

color_trc integer (decoding/encoding,video)

Possible values:

‘bt709’

BT.709

‘gamma22’

BT.470 M

‘gamma28’

BT.470 BG

‘smpte170m’

SMPTE 170 M

‘smpte240m’

SMPTE 240 M

‘linear’

Linear

‘log’

‘log100’

Log

‘log_sqrt’

‘log316’

Log square root

‘iec61966_2_4’

‘iec61966-2-4’

IEC 61966-2-4

‘bt1361’

‘bt1361e’

BT.1361

‘iec61966_2_1’

‘iec61966-2-1’

IEC 61966-2-1

‘bt2020_10’

‘bt2020_10bit’

BT.2020 - 10 bit

‘bt2020_12’

‘bt2020_12bit’

BT.2020 - 12 bit

‘smpte2084’

SMPTE ST 2084

‘smpte428’

‘smpte428_1’

SMPTE ST 428-1

‘arib-std-b67’

ARIB STD-B67

colorspace integer (decoding/encoding,video)

Possible values:

‘rgb’

RGB

‘bt709’

BT.709

‘fcc’

FCC

‘bt470bg’

BT.470 BG

‘smpte170m’

SMPTE 170 M

‘smpte240m’

SMPTE 240 M

‘ycocg’

YCOCG

‘bt2020nc’

‘bt2020_ncl’

BT.2020 NCL

‘bt2020c’

‘bt2020_cl’

BT.2020 CL

‘smpte2085’

SMPTE 2085

‘chroma-derived-nc’

Chroma-derived NCL

‘chroma-derived-c’

Chroma-derived CL

‘ictcp’

ICtCp

color_range integer (decoding/encoding,video)

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

‘tv’

‘mpeg’

MPEG (219*2^(n-8))

‘pc’

‘jpeg’

JPEG (2^n-1)

chroma_sample_location integer (decoding/encoding,video)

Possible values:

‘left’

‘center’

‘topleft’

‘top’

‘bottomleft’

‘bottom’

log_level_offset integer

Set the log level offset.

slices integer (encoding,video)

Number of slices, used in parallelized encoding.

thread_type flags (decoding/encoding,video)

Select which multithreading methods to use.

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

Possible values:

‘slice’

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

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

‘frame’

Decode more than one frame at once.

Default value is ‘slice+frame’.

audio_service_type integer (encoding,audio)

Set audio service type.

Possible values:

‘ma’

Main Audio Service

‘ef’

Effects

‘vi’

Visually Impaired

‘hi’

Hearing Impaired

‘di’

Dialogue

‘co’

Commentary

‘em’

Emergency

‘vo’

Voice Over

‘ka’

Karaoke

request_sample_fmt sample_fmt (decoding,audio)

Set sample format audio decoders should prefer. Default value is none.

pkt_timebase rational number

sub_charenc encoding (decoding,subtitles)

Set the input subtitles character encoding.

field_order field_order (video)

Set/override the field order of the video. Possible values:

‘progressive’

Progressive video

‘tt’

Interlaced video, top field coded and displayed first

‘bb’

Interlaced video, bottom field coded and displayed first

‘tb’

Interlaced video, top coded first, bottom displayed first

‘bt’

Interlaced video, bottom coded first, top displayed first

skip_alpha bool (decoding,video)

Set to 1 to disable processing alpha (transparency). This works like the ‘gray’ flag in the flags option which skips chroma information instead of alpha. Default is 0.

codec_whitelist list (input)

"," separated list of allowed decoders. By default all are allowed.

dump_separator string (input)

Separator used to separate the fields printed on the command line about the Stream parameters. For example, to separate the fields with newlines and indentation:

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

max_pixels integer (decoding/encoding,video)

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

apply_cropping bool (decoding,video)

Enable cropping if cropping parameters are multiples of the required alignment for the left and top parameters. If the alignment is not met the cropping will be partially applied to maintain alignment. Default is 1 (enabled). Note: The required alignment depends on if AV_CODEC_FLAG_UNALIGNED is set and the CPU. AV_CODEC_FLAG_UNALIGNED cannot be changed from the command line. Also hardware decoders will not apply left/top Cropping.