ffserver-all (1)

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NAME

ffserver - ffserver video server

SYNOPSIS

ffserver [options]

DESCRIPTION

ffserver is a streaming server for both audio and video. It supports several live feeds, streaming from files and time shifting on live feeds. You can seek to positions in the past on each live feed, provided you specify a big enough feed storage.

ffserver is configured through a configuration file, which is read at startup. If not explicitly specified, it will read from /etc/ffserver.conf.

ffserver receives prerecorded files or

streams from some ffmpeg instance as input, then streams them over

An ffserver instance will listen on some port as specified in the configuration file. You can launch one or more instances of ffmpeg and send one or more

streams to the port where ffserver is expecting to receive them. Alternately, you can make ffserver launch such ffmpeg instances at startup.

Input streams are called feeds, and each one is specified by a "<Feed>" section in the configuration file.

For each feed you can have different output streams in various formats, each one specified by a "<Stream>" section in the configuration file.

DETAILED DESCRIPTION

ffserver works by forwarding streams encoded by ffmpeg, or pre-recorded streams which are read from disk.

Precisely, ffserver acts as an

server, accepting requests from ffmpeg to acquire the stream to publish, and serving clients or clients requests with the stream media content.

A feed is an

stream created by ffmpeg, and sent to a port where ffserver is listening.

Each feed is identified by a unique name, corresponding to the name of the resource published on ffserver, and is configured by a dedicated "Feed" section in the configuration file.

The feed publish

is given by:

        http://<ffserver_ip_address>:<http_port>/<feed_name>

where ffserver_ip_address is the

address of the machine where ffserver is installed, http_port is the port number of the server (configured through the HTTPPort option), and feed_name is the name of the corresponding feed defined in the configuration file.

Each feed is associated to a file which is stored on disk. This stored file is used to send pre-recorded data to a player as fast as possible when new content is added in real-time to the stream.

A ``live-stream'' or ``stream'' is a resource published by ffserver, and made accessible through the

protocol to clients.

A stream can be connected to a feed, or to a file. In the first case, the published stream is forwarded from the corresponding feed generated by a running instance of ffmpeg, in the second case the stream is read from a pre-recorded file.

Each stream is identified by a unique name, corresponding to the name of the resource served by ffserver, and is configured by a dedicated "Stream" section in the configuration file.

The stream access

is given by:

        http://<ffserver_ip_address>:<http_port>/<stream_name>[<options>]

The stream access

is given by:

        http://<ffserver_ip_address>:<rtsp_port>/<stream_name>[<options>]

stream_name is the name of the corresponding stream defined in the configuration file. options is a list of options specified after the

which affects how the stream is served by ffserver. http_port and rtsp_port are the and ports configured with the options HTTPPort and RTSPPort respectively.

In case the stream is associated to a feed, the encoding parameters must be configured in the stream configuration. They are sent to ffmpeg when setting up the encoding. This allows ffserver to define the encoding parameters used by the ffmpeg encoders.

The ffmpeg override_ffserver commandline option allows one to override the encoding parameters set by the server.

Multiple streams can be connected to the same feed.

For example, you can have a situation described by the following graph:

                       _________       __________
                      |         |     |          |
        ffmpeg 1 -----| feed 1  |-----| stream 1 |
            \         |_________|\    |__________|
             \                    \
              \                    \   __________
               \                    \ |          |
                \                    \| stream 2 |
                 \                    |__________|
                  \
                   \   _________       __________
                    \ |         |     |          |
                     \| feed 2  |-----| stream 3 |
                      |_________|     |__________|
        
                       _________       __________
                      |         |     |          |
        ffmpeg 2 -----| feed 3  |-----| stream 4 |
                      |_________|     |__________|
        
                       _________       __________
                      |         |     |          |
                      | file 1  |-----| stream 5 |
                      |_________|     |__________|

FFM, FFM2

formats

and are formats used by ffserver. They allow storing a wide variety of video and audio streams and encoding options, and can store a moving time segment of an infinite movie or a whole movie.

is version specific, and there is limited compatibility of files generated by one version of ffmpeg/ffserver and another version of ffmpeg/ffserver. It may work but it is not guaranteed to work.

is extensible while maintaining compatibility and should work between differing versions of tools. is the default.

Status stream

ffserver supports an interface which exposes the current status of the server.

Simply point your browser to the address of the special status stream specified in the configuration file.

For example if you have:

        <Stream status.html>
        Format status
        
        # Only allow local people to get the status
        ACL allow localhost
        ACL allow 192.168.0.0 192.168.255.255
        </Stream>

then the server will post a page with the status information when the special stream status.html is requested.

How do I make it work?

As a simple test, just run the following two command lines where is some file which you can decode with ffmpeg:

        ffserver -f doc/ffserver.conf &
        ffmpeg -i INPUTFILE http://localhost:8090/feed1.ffm

At this point you should be able to go to your Windows machine and fire up Windows Media Player (

). Go to Open and enter

            http://<linuxbox>:8090/test.asf

You should (after a short delay) see video and hear audio.

trying to stream test1.mpg doesn't work with as it tries to transfer the entire file before starting to play. The same is true of files.

You should edit the ffserver.conf file to suit your needs (in terms of frame rates etc). Then install ffserver and ffmpeg, write a script to start them up, and off you go.

What else can it do?

You can replay video from .ffm files that was recorded earlier. However, there are a number of caveats, including the fact that the ffserver parameters must match the original parameters used to record the file. If they do not, then ffserver deletes the file before recording into it. (Now that I write this, it seems broken).

You can fiddle with many of the codec choices and encoding parameters, and there are a bunch more parameters that you cannot control. Post a message to the mailing list if there are some 'must have' parameters. Look in ffserver.conf for a list of the currently available controls.

It will automatically generate the

or files that are often used in browsers. These files are actually redirections to the underlying or file. The reason for this is that the browser often fetches the entire file before starting up the external viewer. The redirection files are very small and can be transferred quickly. [The stream itself is often 'infinite' and thus the browser tries to download it and never finishes.]

Tips

* When you connect to a live stream, most players ( etc) want to buffer a certain number of seconds of material so that they can display the signal continuously. However, ffserver (by default) starts sending data in realtime. This means that there is a pause of a few seconds while the buffering is being done by the player. The good news is that this can be cured by adding a '?buffer=5' to the end of the This means that the stream should start 5 seconds in the past --- and so the first 5 seconds of the stream are sent as fast as the network will allow. It will then slow down to real time. This noticeably improves the startup experience.

You can also add a 'Preroll 15' statement into the ffserver.conf that will add the 15 second prebuffering on all requests that do not otherwise specify a time. In addition, ffserver will skip frames until a key_frame is found. This further reduces the startup delay by not transferring data that will be discarded.

Why does the ?buffer / Preroll stop working after a time?

It turns out that (on my machine at least) the number of frames successfully grabbed is marginally less than the number that ought to be grabbed. This means that the timestamp in the encoded data stream gets behind realtime. This means that if you say 'Preroll 10', then when the stream gets 10 or more seconds behind, there is no Preroll left.

Fixing this requires a change in the internals of how timestamps are handled.

Does the ?date= stuff work.

Yes (subject to the limitation outlined above). Also note that whenever you start ffserver, it deletes the ffm file (if any parameters have changed), thus wiping out what you had recorded before.

The format of the "?date=xxxxxx" is fairly flexible. You should use one of the following formats (the 'T' is literal):

        * YYYY-MM-DDTHH:MM:SS     (localtime)
        * YYYY-MM-DDTHH:MM:SSZ    (UTC)

You can omit the YYYY-MM-DD, and then it refers to the current day. However note that ?date=16:00:00 refers to 16:00 on the current day --- this may be in the future and so is unlikely to be useful.

You use this by adding the ?date= to the end of the

for the stream. For example: http://localhost:8080/test.asf?date=2002-07-26T23:05:00.

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 unit prefixes, for example: 'K', 'M', or 'G'.

If 'i' is appended to the

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 unit prefix multiplies the value by 8. This allows using, for example: '', '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.

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.

stream_type[:stream_index]

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 stream_index is given, then it matches stream number stream_index of this type. Otherwise, it matches all streams of this type.

p:program_id[:stream_index]

If stream_index is given, then it matches the stream with number stream_index in the program with the id program_id. Otherwise, it matches all streams in the program.

#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.

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 name filter_name. Use the -filters option to get a list of all filters.

-version

Show version.

-formats

Show available formats (including devices).

-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.

-colors

Show recognized color names.

-sources device[,opt1=val1[,opt2=val2]...]

Show autodetected sources of the intput 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 [repeat+]loglevel | -v [repeat+]loglevel

Set the logging level used by the library. Adding ``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. ``repeat'' can also be used alone. If ``repeat'' is used alone, and with no prior loglevel set, the default loglevel will be used. If multiple loglevel parameters are given, using 'repeat' will not change the 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 and assert failure. This is not currently used for anything.

fatal, 8

Only show fatal errors. These are errors after which the process absolutely cannot continue after.

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

By default the program logs to stderr, if coloring is supported by the terminal, colors are used to mark errors and warnings. Log coloring can be disabled setting the environment variable

AV_LOG_FORCE_NOCOLOR

or

NO_COLOR

, or can be forced setting the environment variable

AV_LOG_FORCE_COLOR

. The use of the environment variable

NO_COLOR

is deprecated and will be dropped in a following FFmpeg version.

-report

Dump full command line and console output to a file named "program-YYYYMMDD-HHMMSS.log" in the current directory. This file can be useful for bug reports. It also implies "-loglevel verbose".

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

-opencl_bench

This option is used to benchmark all available OpenCL devices and print the results. This option is only available when FFmpeg has been compiled with "--enable-opencl".

When FFmpeg is configured with "--enable-opencl", the options for the global OpenCL context are set via -opencl_options. See the ``OpenCL Options'' section in the ffmpeg-utils manual for the complete list of supported options. Amongst others, these options include the ability to select a specific platform and device to run the OpenCL code on. By default, FFmpeg will run on the first device of the first platform. While the options for the global OpenCL context provide flexibility to the user in selecting the OpenCL device of their choice, most users would probably want to select the fastest OpenCL device for their system.

This option assists the selection of the most efficient configuration by identifying the appropriate device for the user's system. The built-in benchmark is run on all the OpenCL devices and the performance is measured for each device. The devices in the results list are sorted based on their performance with the fastest device listed first. The user can subsequently invoke ffmpeg using the device deemed most appropriate via -opencl_options to obtain the best performance for the OpenCL accelerated code.

Typical usage to use the fastest OpenCL device involve the following steps.

Run the command:

        ffmpeg -opencl_bench

Note down the platform

ID

(pidx) and device

ID

(didx) of the first i.e. fastest device in the list. Select the platform and device using the command:

        ffmpeg -opencl_options platform_idx=<pidx>:device_idx=<didx> ...

-opencl_options options (global)

Set OpenCL environment options. This option is only available when FFmpeg has been compiled with "--enable-opencl".

options must be a list of key=value option pairs separated by ':'. See the ``OpenCL Options'' section in the ffmpeg-utils manual for the list of supported options.

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

file, use the id3v2_version private option of the 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.

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.

Main options

-f configfile

Read configuration file configfile. If not specified it will read by default from /etc/ffserver.conf.

-n

Enable no-launch mode. This option disables all the "Launch" directives within the various "<Feed>" sections. Since ffserver will not launch any ffmpeg instances, you will have to launch them manually.

-d

Enable debug mode. This option increases log verbosity, and directs log messages to stdout. When specified, the CustomLog option is ignored.

CONFIGURATION FILE SYNTAX

ffserver reads a configuration file containing global options and settings for each stream and feed.

The configuration file consists of global options and dedicated sections, which must be introduced by "<

>`` on a separate line and must be terminated by a line in the form ''</>". is optional.

Currently the following sections are recognized: Feed, Stream, Redirect.

A line starting with "#" is ignored and treated as a comment.

Name of options and sections are case-insensitive.

ACL

syntax

An (Access Control List) specifies the address which are allowed to access a given stream, or to write a given feed.

It accepts the folling forms

*

Allow/deny access to address.

        ACL ALLOW <address>
        ACL DENY <address>

*

Allow/deny access to ranges of addresses from first_address to last_address.

        ACL ALLOW <first_address> <last_address>
        ACL DENY <first_address> <last_address>

You can repeat the

allow/deny as often as you like. It is on a per stream basis. The first match defines the action. If there are no matches, then the default is the inverse of the last statement.

Thus '

allow localhost' only allows access from localhost. ' deny 1.0.0.0 1.255.255.255' would deny the whole of network 1 and allow everybody else.

Global options

HTTPPort port_number

Port port_number

RTSPPort port_number

HTTPPort sets the

HTTP

server listening

TCP

port number, RTSPPort sets the

RTSP

server listening

TCP

port number.

Port is the equivalent of HTTPPort and is deprecated.

You must select a different port from your standard

HTTP

web server if it is running on the same computer.

If not specified, no corresponding server will be created.

HTTPBindAddress ip_address

BindAddress ip_address

RTSPBindAddress ip_address

Set address on which the

HTTP/RTSP

server is bound. Only useful if you have several network interfaces.

BindAddress is the equivalent of HTTPBindAddress and is deprecated.

MaxHTTPConnections n

Set number of simultaneous

HTTP

connections that can be handled. It has to be defined before the MaxClients parameter, since it defines the MaxClients maximum limit.

Default value is 2000.

MaxClients n

Set number of simultaneous requests that can be handled. Since ffserver is very fast, it is more likely that you will want to leave this high and use MaxBandwidth.

Default value is 5.

MaxBandwidth kbps

Set the maximum amount of kbit/sec that you are prepared to consume when streaming to clients.

Default value is 1000.

CustomLog filename

Set access log file (uses standard Apache log file format). '-' is the standard output.

If not specified ffserver will produce no log.

In case the commandline option -d is specified this option is ignored, and the log is written to standard output.

NoDaemon

Set no-daemon mode. This option is currently ignored since now ffserver will always work in no-daemon mode, and is deprecated.

UseDefaults

NoDefaults

Control whether default codec options are used for the all streams or not. Each stream may overwrite this setting for its own. Default is UseDefaults. The lastest occurrence overrides previous if multiple definitions.

Feed section

A Feed section defines a feed provided to ffserver.

Each live feed contains one video and/or audio sequence coming from an ffmpeg encoder or another ffserver. This sequence may be encoded simultaneously with several codecs at several resolutions.

A feed instance specification is introduced by a line in the form:

        <Feed FEED_FILENAME>

where

specifies the unique name of the stream.

The following options are recognized within a Feed section.

File filename

ReadOnlyFile filename

Set the path where the feed file is stored on disk.

If not specified, the /tmp/FEED.ffm is assumed, where

FEED

is the feed name.

If ReadOnlyFile is used the file is marked as read-only and it will not be deleted or updated.

Truncate

Truncate the feed file, rather than appending to it. By default ffserver will append data to the file, until the maximum file size value is reached (see FileMaxSize option).

FileMaxSize size

Set maximum size of the feed file in bytes. 0 means unlimited. The postfixes "K" (2^10), "M" (2^20), and "G" (2^30) are recognized.

Default value is 5M.

Launch args

Launch an ffmpeg command when creating ffserver.

args must be a sequence of arguments to be provided to an ffmpeg instance. The first provided argument is ignored, and it is replaced by a path with the same dirname of the ffserver instance, followed by the remaining argument and terminated with a path corresponding to the feed.

When the launched process exits, ffserver will launch another program instance.

In case you need a more complex ffmpeg configuration, e.g. if you need to generate multiple

FFM

feeds with a single ffmpeg instance, you should launch ffmpeg by hand.

This option is ignored in case the commandline option -n is specified.

ACL

spec

Specify the list of

IP

address which are allowed or denied to write the feed. Multiple

ACL

options can be specified.

Stream section

A Stream section defines a stream provided by ffserver, and identified by a single name.

The stream is sent when answering a request containing the stream name.

A stream section must be introduced by the line:

        <Stream STREAM_NAME>

where

specifies the unique name of the stream.

The following options are recognized within a Stream section.

Encoding options are marked with the encoding tag, and they are used to set the encoding parameters, and are mapped to libavcodec encoding options. Not all encoding options are supported, in particular it is not possible to set encoder private options. In order to override the encoding options specified by ffserver, you can use the ffmpeg override_ffserver commandline option.

Only one of the Feed and File options should be set.

Feed feed_name

Set the input feed. feed_name must correspond to an existing feed defined in a "Feed" section.

When this option is set, encoding options are used to setup the encoding operated by the remote ffmpeg process.

File filename

Set the filename of the pre-recorded input file to stream.

When this option is set, encoding options are ignored and the input file content is re-streamed as is.

Format format_name

Set the format of the output stream.

Must be the name of a format recognized by FFmpeg. If set to status, it is treated as a status stream.

InputFormat format_name

Set input format. If not specified, it is automatically guessed.

Preroll n

Set this to the number of seconds backwards in time to start. Note that most players will buffer 5-10 seconds of video, and also you need to allow for a keyframe to appear in the data stream.

Default value is 0.

StartSendOnKey

Do not send stream until it gets the first key frame. By default ffserver will send data immediately.

MaxTime n

Set the number of seconds to run. This value set the maximum duration of the stream a client will be able to receive.

A value of 0 means that no limit is set on the stream duration.

ACL

spec

Set

ACL

for the stream.

DynamicACL spec

RTSPOption option

MulticastAddress address

MulticastPort port

MulticastTTL integer

NoLoop

FaviconURL url

Set favicon (favourite icon) for the server status page. It is ignored for regular streams.

Author value

Comment value

Copyright value

Title value

Set metadata corresponding to the option. All these options are deprecated in favor of Metadata.

Metadata key value

Set metadata value on the output stream.

UseDefaults

NoDefaults

Control whether default codec options are used for the stream or not. Default is UseDefaults unless disabled globally.

NoAudio

NoVideo

Suppress audio/video.

AudioCodec codec_name (encoding,audio)

Set audio codec.

AudioBitRate rate (encoding,audio)

Set bitrate for the audio stream in kbits per second.

AudioChannels n (encoding,audio)

Set number of audio channels.

AudioSampleRate n (encoding,audio)

Set sampling frequency for audio. When using low bitrates, you should lower this frequency to 22050 or 11025. The supported frequencies depend on the selected audio codec.

AVOptionAudio [codec:]option value (encoding,audio)

Set generic or private option for audio stream. Private option must be prefixed with codec name or codec must be defined before.

AVPresetAudio preset (encoding,audio)

Set preset for audio stream.

VideoCodec codec_name (encoding,video)

Set video codec.

VideoBitRate n (encoding,video)

Set bitrate for the video stream in kbits per second.

VideoBitRateRange range (encoding,video)

Set video bitrate range.

A range must be specified in the form minrate-maxrate, and specifies the minrate and maxrate encoding options expressed in kbits per second.

VideoBitRateRangeTolerance n (encoding,video)

Set video bitrate tolerance in kbits per second.

PixelFormat pixel_format (encoding,video)

Set video pixel format.

Debug integer (encoding,video)

Set video debug encoding option.

Strict integer (encoding,video)

Set video strict encoding option.

VideoBufferSize n (encoding,video)

Set ratecontrol buffer size, expressed in

KB.

VideoFrameRate n (encoding,video)

Set number of video frames per second.

VideoSize (encoding,video)

Set size of the video frame, must be an abbreviation or in the form WxH. See the Video size section in the ffmpeg-utils(1) manual.

Default value is "160x128".

VideoIntraOnly (encoding,video)

Transmit only intra frames (useful for low bitrates, but kills frame rate).

VideoGopSize n (encoding,video)

If non-intra only, an intra frame is transmitted every VideoGopSize frames. Video synchronization can only begin at an intra frame.

VideoTag tag (encoding,video)

Set video tag.

VideoHighQuality (encoding,video)

Video4MotionVector (encoding,video)

BitExact (encoding,video)

Set bitexact encoding flag.

IdctSimple (encoding,video)

Set simple

IDCT

algorithm.

Qscale n (encoding,video)

Enable constant quality encoding, and set video qscale (quantization scale) value, expressed in n

QP

units.

VideoQMin n (encoding,video)

VideoQMax n (encoding,video)

Set video qmin/qmax.

VideoQDiff integer (encoding,video)

Set video qdiff encoding option.

LumiMask float (encoding,video)

DarkMask float (encoding,video)

Set lumi_mask/dark_mask encoding options.

AVOptionVideo [codec:]option value (encoding,video)

Set generic or private option for video stream. Private option must be prefixed with codec name or codec must be defined before.

AVPresetVideo preset (encoding,video)

Set preset for video stream.

preset must be the path of a preset file.

Server status stream

A server status stream is a special stream which is used to show statistics about the ffserver operations.

It must be specified setting the option Format to status.

Redirect section

A redirect section specifies where to redirect the requested to another page.

A redirect section must be introduced by the line:

        <Redirect NAME>

where

is the name of the page which should be redirected.

It only accepts the option

, which specify the redirection

STREAM EXAMPLES

*

Multipart

JPEG

        <Stream test.mjpg>
        Feed feed1.ffm
        Format mpjpeg
        VideoFrameRate 2
        VideoIntraOnly
        NoAudio
        Strict -1
        </Stream>

*

Single

JPEG

        <Stream test.jpg>
        Feed feed1.ffm
        Format jpeg
        VideoFrameRate 2
        VideoIntraOnly
        VideoSize 352x240
        NoAudio
        Strict -1
        </Stream>

*

Flash

        <Stream test.swf>
        Feed feed1.ffm
        Format swf
        VideoFrameRate 2
        VideoIntraOnly
        NoAudio
        </Stream>

*

ASF

compatible

        <Stream test.asf>
        Feed feed1.ffm
        Format asf
        VideoFrameRate 15
        VideoSize 352x240
        VideoBitRate 256
        VideoBufferSize 40
        VideoGopSize 30
        AudioBitRate 64
        StartSendOnKey
        </Stream>

*

MP3

audio

        <Stream test.mp3>
        Feed feed1.ffm
        Format mp2
        AudioCodec mp3
        AudioBitRate 64
        AudioChannels 1
        AudioSampleRate 44100
        NoVideo
        </Stream>

*

Ogg Vorbis audio

        <Stream test.ogg>
        Feed feed1.ffm
        Metadata title "Stream title"
        AudioBitRate 64
        AudioChannels 2
        AudioSampleRate 44100
        NoVideo
        </Stream>

*

Real with audio only at 32 kbits

        <Stream test.ra>
        Feed feed1.ffm
        Format rm
        AudioBitRate 32
        NoVideo
        </Stream>

*

Real with audio and video at 64 kbits

        <Stream test.rm>
        Feed feed1.ffm
        Format rm
        AudioBitRate 32
        VideoBitRate 128
        VideoFrameRate 25
        VideoGopSize 25
        </Stream>

*

For stream coming from a file: you only need to set the input filename and optionally a new format.

        <Stream file.rm>
        File "/usr/local/httpd/htdocs/tlive.rm"
        NoAudio
        </Stream>

        
        <Stream file.asf>
        File "/usr/local/httpd/htdocs/test.asf"
        NoAudio
        Metadata author "Me"
        Metadata copyright "Super MegaCorp"
        Metadata title "Test stream from disk"
        Metadata comment "Test comment"
        </Stream>

SYNTAX

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

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.

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

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

If the year-month-day part is not specified it takes the current year-month-day.

Time duration

There are two accepted syntaxes for expressing time duration.

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

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

or

        [-]<S>+[.<m>...]

S expresses the number of seconds, with the optional decimal part m.

In both expressions, the optional - indicates negative duration.

Examples

The following examples are all valid time duration:

55

55 seconds

12:03:45

12 hours, 03 minutes and 45 seconds

23.189

23.189 seconds

Video size

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

The following abbreviations are recognized:

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

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

Ratio

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

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

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

Color

It can be the name of a color 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

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

downmix

DL+DR

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

*

the name of a standard channel layout (e.g. mono, stereo, 4.0, quad, 5.0, etc.)

*

the name of a single channel (e.g.

FL

,

FR

,

FC

,

LFE

, etc.)

*

a number of channels, in decimal, optionally followed by 'c', yielding the default channel layout for that number of channels (see the function "av_get_default_channel_layout")

*

a channel layout mask, in hexadecimal starting with ``0x'' (see the "AV_CH_*" macros in libavutil/channel_layout.h.

Starting from libavutil version 53 the trailing character ``c'' to specify a number of channels will be required, while a channel layout mask could also be specified as a decimal number (if and only if not followed by ``c'').

See also the function "av_get_channel_layout" defined in libavutil/channel_layout.h.

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.

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.

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 maximum 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.

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

"+" works like

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 '

', '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 / 2^40

E

10^18 / 2^50

Z

10^21 / 2^60

Y

10^24 / 2^70

OPENCL OPTIONS

When FFmpeg is configured with "--enable-opencl", it is possible to set the options for the global OpenCL context.

The list of supported options follows:

build_options

Set build options used to compile the registered kernels.

See reference ``OpenCL Specification Version: 1.2 chapter 5.6.4''.

platform_idx

Select the index of the platform to run OpenCL code.

The specified index must be one of the indexes in the device list which can be obtained with "ffmpeg -opencl_bench" or "av_opencl_get_device_list()".

device_idx

Select the index of the device used to run OpenCL code.

The specified index must be one of the indexes in the device list which can be obtained with "ffmpeg -opencl_bench" or "av_opencl_get_device_list()".

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

for programmatic use.

The list of supported options follow:

b integer (encoding,audio,video)

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

ab integer (encoding,audio)

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

bt integer (encoding,video)

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

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

Set generic flags.

Possible values:

mv4

Use four motion vector by macroblock (mpeg4).

qpel

Use 1/4 pel motion compensation.

loop

Use loop filter.

qscale

Use fixed qscale.

gmc

Use gmc.

mv0

Always try a mb with mv=<0,0>.

input_preserved

pass1

Use internal 2pass ratecontrol in first pass mode.

pass2

Use internal 2pass ratecontrol in second pass mode.

gray

Only decode/encode grayscale.

emu_edge

Do not draw edges.

psnr

Set error[?] variables during encoding.

truncated

naq

Normalize adaptive quantization.

ildct

Use interlaced

DCT.

low_delay

Force low delay.

global_header

Place global headers in extradata instead of every keyframe.

bitexact

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

aic

Apply H263 advanced intra coding / mpeg4 ac prediction.

cbp

Deprecated, use mpegvideo private options instead.

qprd

Deprecated, use mpegvideo private options instead.

ilme

Apply interlaced motion estimation.

cgop

Use closed gop.

me_method integer (encoding,video)

Set motion estimation method.

Possible values:

zero

zero motion estimation (fastest)

full

full motion estimation (slowest)

epzs

EPZS

motion estimation (default)

esa

esa motion estimation (alias for full)

tesa

tesa motion estimation

dia

dia motion estimation (alias for epzs)

log

log motion estimation

phods

phods motion estimation

x1

X1 motion estimation

hex

hex motion estimation

umh

umh motion estimation

iter

iter motion estimation

extradata_size integer

Set extradata size.

time_base rational number

Set codec time base.

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

g integer (encoding,video)

Set the group of picture size. Default value is 12.

ar integer (decoding/encoding,audio)

Set audio sampling rate (in Hz).

ac integer (decoding/encoding,audio)

Set number of audio channels.

cutoff integer (encoding,audio)

Set cutoff bandwidth.

frame_size integer (encoding,audio)

Set audio frame size.

Each submitted frame except the last must contain exactly frame_size samples per channel. May be 0 when the codec has

CODEC_CAP_VARIABLE_FRAME_SIZE

set, in that case the frame size is not restricted. It is set by some decoders to indicate constant frame size.

frame_number integer

Set the frame number.

delay integer

qcomp float (encoding,video)

Set video quantizer scale compression (

VBR

). It is used as a constant in the ratecontrol equation. Recommended range for default rc_eq: 0.0-1.0.

qblur float (encoding,video)

Set video quantizer scale blur (

VBR

).

qmin integer (encoding,video)

Set min video quantizer scale (

VBR

). Must be included between -1 and 69, default value is 2.

qmax integer (encoding,video)

Set max video quantizer scale (

VBR

). Must be included between -1 and 1024, default value is 31.

qdiff integer (encoding,video)

Set max difference between the quantizer scale (

VBR

).

bf integer (encoding,video)

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

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

Default value is 0.

b_qfactor float (encoding,video)

Set qp factor between P and B frames.

rc_strategy integer (encoding,video)

Set ratecontrol method.

b_strategy integer (encoding,video)

Set strategy to choose between I/P/B-frames.

ps integer (encoding,video)

Set

RTP

payload size in bytes.

mv_bits integer

header_bits integer

i_tex_bits integer

p_tex_bits integer

i_count integer

p_count integer

skip_count integer

misc_bits integer

frame_bits integer

codec_tag integer

bug flags (decoding,video)

Workaround not auto detected encoder bugs.

Possible values:

autodetect

old_msmpeg4

some old lavc generated msmpeg4v3 files (no autodetection)

xvid_ilace

Xvid interlacing bug (autodetected if fourcc==XVIX)

ump4

(autodetected if fourcc==UMP4)

no_padding

padding bug (autodetected)

amv

ac_vlc

illegal vlc bug (autodetected per fourcc)

qpel_chroma

std_qpel

old standard qpel (autodetected per fourcc/version)

qpel_chroma2

direct_blocksize

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

edge

edge padding bug (autodetected per fourcc/version)

hpel_chroma

dc_clip

ms

Workaround various bugs in microsoft broken decoders.

trunc

trancated frames

lelim integer (encoding,video)

Set single coefficient elimination threshold for luminance (negative values also consider

DC

coefficient).

celim integer (encoding,video)

Set single coefficient elimination threshold for chrominance (negative values also consider dc coefficient)

strict integer (decoding/encoding,audio,video)

Specify how strictly to follow the standards.

Possible values:

very

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

strict

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

normal

unofficial

allow unofficial extensions

experimental

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

b_qoffset float (encoding,video)

Set

QP

offset between P and B frames.

err_detect flags (decoding,audio,video)

Set error detection flags.

Possible values:

crccheck

verify embedded CRCs

bitstream

detect bitstream specification deviations

buffer

detect improper bitstream length

explode

abort decoding on minor error detection

ignore_err

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

careful

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

compliant

consider all spec non compliancies as errors

aggressive

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

has_b_frames integer

block_align integer

mpeg_quant integer (encoding,video)

Use

MPEG

quantizers instead of H.263.

qsquish float (encoding,video)

How to keep quantizer between qmin and qmax (0 = clip, 1 = use differentiable function).

rc_qmod_amp float (encoding,video)

Set experimental quantizer modulation.

rc_qmod_freq integer (encoding,video)

Set experimental quantizer modulation.

rc_override_count integer

rc_eq string (encoding,video)

Set rate control equation. When computing the expression, besides the standard functions defined in the section 'Expression Evaluation', the following functions are available: bits2qp(bits), qp2bits(qp). Also the following constants are available: iTex pTex tex mv fCode iCount mcVar var isI isP isB avgQP qComp avgIITex avgPITex avgPPTex avgBPTex avgTex.

maxrate integer (encoding,audio,video)

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

minrate integer (encoding,audio,video)

Set min bitrate tolerance (in bits/s). Most useful in setting up a

CBR

encode. It is of little use elsewise.

bufsize integer (encoding,audio,video)

Set ratecontrol buffer size (in bits).

rc_buf_aggressivity float (encoding,video)

Currently useless.

i_qfactor float (encoding,video)

Set

QP

factor between P and I frames.

i_qoffset float (encoding,video)

Set

QP

offset between P and I frames.

rc_init_cplx float (encoding,video)

Set initial complexity for 1-pass encoding.

dct integer (encoding,video)

Set

DCT

algorithm.

Possible values:

auto

autoselect a good one (default)

fastint

fast integer

int

accurate integer

mmx

altivec

faan

floating point

AAN DCT

lumi_mask float (encoding,video)

Compress bright areas stronger than medium ones.

tcplx_mask float (encoding,video)

Set temporal complexity masking.

scplx_mask float (encoding,video)

Set spatial complexity masking.

p_mask float (encoding,video)

Set inter masking.

dark_mask float (encoding,video)

Compress dark areas stronger than medium ones.

idct integer (decoding/encoding,video)

Select

IDCT

implementation.

Possible values:

auto

int

simple

simplemmx

simpleauto

Automatically pick a

IDCT

compatible with the simple one

arm

altivec

sh4

simplearm

simplearmv5te

simplearmv6

simpleneon

simplealpha

ipp

xvidmmx

faani

floating point

AAN IDCT

slice_count integer

ec flags (decoding,video)

Set error concealment strategy.

Possible values:

guess_mvs

iterative motion vector (

MV

) search (slow)

deblock

use strong deblock filter for damaged MBs

favor_inter

favor predicting from the previous frame instead of the current

bits_per_coded_sample integer

pred integer (encoding,video)

Set prediction method.

Possible values:

left

plane

median

aspect rational number (encoding,video)

Set sample aspect ratio.

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

Print specific debug info.

Possible values:

pict

picture info

rc

rate control

bitstream

mb_type

macroblock (

MB

) type

qp

per-block quantization parameter (

QP

)

mv

motion vector

dct_coeff

green_metadata

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

skip

startcode

pts

er

error recognition

mmco

memory management control operations (H.264)

bugs

vis_qp

visualize quantization parameter (

QP

), lower

QP

are tinted greener

vis_mb_type

visualize block types

buffers

picture buffer allocations

thread_ops

threading operations

nomc

skip motion compensation

vismv integer (decoding,video)

Visualize motion vectors (MVs).

This option is deprecated, see the codecview filter instead.

Possible values:

pf

forward predicted MVs of P-frames

bf

forward predicted MVs of B-frames

bb

backward predicted MVs of B-frames

cmp integer (encoding,video)

Set full pel me compare function.

Possible values:

sad

sum of absolute differences, fast (default)

sse

sum of squared errors

satd

sum of absolute Hadamard transformed differences

dct

sum of absolute

DCT

transformed differences

psnr

sum of squared quantization errors (avoid, low quality)

bit

number of bits needed for the block

rd

rate distortion optimal, slow

zero

0

vsad

sum of absolute vertical differences

vsse

sum of squared vertical differences

nsse

noise preserving sum of squared differences

w53

5/3 wavelet, only used in snow

w97

9/7 wavelet, only used in snow

dctmax

chroma

subcmp integer (encoding,video)

Set sub pel me compare function.

Possible values:

sad

sum of absolute differences, fast (default)

sse

sum of squared errors

satd

sum of absolute Hadamard transformed differences

dct

sum of absolute

DCT

transformed differences

psnr

sum of squared quantization errors (avoid, low quality)

bit

number of bits needed for the block

rd

rate distortion optimal, slow

zero

0

vsad

sum of absolute vertical differences

vsse

sum of squared vertical differences

nsse

noise preserving sum of squared differences

w53

5/3 wavelet, only used in snow

w97

9/7 wavelet, only used in snow

dctmax

chroma

mbcmp integer (encoding,video)

Set macroblock compare function.

Possible values:

sad

sum of absolute differences, fast (default)

sse

sum of squared errors

satd

sum of absolute Hadamard transformed differences

dct

sum of absolute

DCT

transformed differences

psnr

sum of squared quantization errors (avoid, low quality)

bit

number of bits needed for the block

rd

rate distortion optimal, slow

zero

0

vsad

sum of absolute vertical differences

vsse

sum of squared vertical differences

nsse

noise preserving sum of squared differences

w53

5/3 wavelet, only used in snow

w97

9/7 wavelet, only used in snow

dctmax

chroma

ildctcmp integer (encoding,video)

Set interlaced dct compare function.

Possible values:

sad

sum of absolute differences, fast (default)

sse

sum of squared errors

satd

sum of absolute Hadamard transformed differences

dct

sum of absolute

DCT

transformed differences

psnr

sum of squared quantization errors (avoid, low quality)

bit

number of bits needed for the block

rd

rate distortion optimal, slow

zero

0

vsad

sum of absolute vertical differences

vsse

sum of squared vertical differences

nsse

noise preserving sum of squared differences

w53

5/3 wavelet, only used in snow

w97

9/7 wavelet, only used in snow

dctmax

chroma

dia_size integer (encoding,video)

Set diamond type & size for motion estimation.

last_pred integer (encoding,video)

Set amount of motion predictors from the previous frame.

preme integer (encoding,video)

Set pre motion estimation.

precmp integer (encoding,video)

Set pre motion estimation compare function.

Possible values:

sad

sum of absolute differences, fast (default)

sse

sum of squared errors

satd

sum of absolute Hadamard transformed differences

dct

sum of absolute

DCT

transformed differences

psnr

sum of squared quantization errors (avoid, low quality)

bit

number of bits needed for the block

rd

rate distortion optimal, slow

zero

0

vsad

sum of absolute vertical differences

vsse

sum of squared vertical differences

nsse

noise preserving sum of squared differences

w53

5/3 wavelet, only used in snow

w97

9/7 wavelet, only used in snow

dctmax

chroma

pre_dia_size integer (encoding,video)

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

subq integer (encoding,video)

Set sub pel motion estimation quality.

dtg_active_format integer

me_range integer (encoding,video)

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

ibias integer (encoding,video)

Set intra quant bias.

pbias integer (encoding,video)

Set inter quant bias.

color_table_id integer

global_quality integer (encoding,audio,video)

coder integer (encoding,video)

Possible values:

vlc

variable length coder / huffman coder

ac

arithmetic coder

raw

raw (no encoding)

rle

run-length coder

deflate

deflate-based coder

context integer (encoding,video)

Set context model.

slice_flags integer

xvmc_acceleration integer

mbd integer (encoding,video)

Set macroblock decision algorithm (high quality mode).

Possible values:

simple

use mbcmp (default)

bits

use fewest bits

rd

use best rate distortion

stream_codec_tag integer

sc_threshold integer (encoding,video)

Set scene change threshold.

lmin integer (encoding,video)

Set min lagrange factor (

VBR

).

lmax integer (encoding,video)

Set max lagrange factor (

VBR

).

nr integer (encoding,video)

Set noise reduction.

rc_init_occupancy integer (encoding,video)

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

flags2 flags (decoding/encoding,audio,video)

Possible values:

fast

Allow non spec compliant speedup tricks.

sgop

Deprecated, use mpegvideo private options instead.

noout

Skip bitstream encoding.

ignorecrop

Ignore cropping information from sps.

local_header

Place global headers at every keyframe instead of in extradata.

chunks

Frame data might be split into multiple chunks.

showall

Show all frames before the first keyframe.

skiprd

Deprecated, use mpegvideo private options instead.

export_mvs

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

error integer (encoding,video)

qns integer (encoding,video)

Deprecated, use mpegvideo private options instead.

threads integer (decoding/encoding,video)

Possible values:

auto

detect a good number of threads

me_threshold integer (encoding,video)

Set motion estimation threshold.

mb_threshold integer (encoding,video)

Set macroblock threshold.

dc integer (encoding,video)

Set intra_dc_precision.

nssew integer (encoding,video)

Set nsse weight.

skip_top integer (decoding,video)

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

skip_bottom integer (decoding,video)

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

profile integer (encoding,audio,video)

Possible values:

unknown

aac_main

aac_low

aac_ssr

aac_ltp

aac_he

aac_he_v2

aac_ld

aac_eld

mpeg2_aac_low

mpeg2_aac_he

mpeg4_sp

mpeg4_core

mpeg4_main

mpeg4_asp

dts

dts_es

dts_96_24

dts_hd_hra

dts_hd_ma

level integer (encoding,audio,video)

Possible values:

unknown

lowres integer (decoding,audio,video)

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

skip_threshold integer (encoding,video)

Set frame skip threshold.

skip_factor integer (encoding,video)

Set frame skip factor.

skip_exp integer (encoding,video)

Set frame skip exponent. Negative values behave identical to the corresponding positive ones, except that the score is normalized. Positive values exist primarily for compatibility reasons and are not so useful.

skipcmp integer (encoding,video)

Set frame skip compare function.

Possible values:

sad

sum of absolute differences, fast (default)

sse

sum of squared errors

satd

sum of absolute Hadamard transformed differences

dct

sum of absolute

DCT

transformed differences

psnr

sum of squared quantization errors (avoid, low quality)

bit

number of bits needed for the block

rd

rate distortion optimal, slow

zero

0

vsad

sum of absolute vertical differences

vsse

sum of squared vertical differences

nsse

noise preserving sum of squared differences

w53

5/3 wavelet, only used in snow

w97

9/7 wavelet, only used in snow

dctmax

chroma

border_mask float (encoding,video)

Increase the quantizer for macroblocks close to borders.

mblmin integer (encoding,video)

Set min macroblock lagrange factor (

VBR

).

mblmax integer (encoding,video)

Set max macroblock lagrange factor (

VBR

).

mepc integer (encoding,video)

Set motion estimation bitrate penalty compensation (1.0 = 256).

skip_loop_filter integer (decoding,video)

skip_idct integer (decoding,video)

skip_frame integer (decoding,video)

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

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

Possible values:

none

Discard no frame.

default

Discard useless frames like 0-sized frames.

noref

Discard all non-reference frames.

bidir

Discard all bidirectional frames.

nokey

Discard all frames excepts keyframes.

all

Discard all frames.

Default value is default.

bidir_refine integer (encoding,video)

Refine the two motion vectors used in bidirectional macroblocks.

brd_scale integer (encoding,video)

Downscale frames for dynamic B-frame decision.

keyint_min integer (encoding,video)

Set minimum interval between IDR-frames.

refs integer (encoding,video)

Set reference frames to consider for motion compensation.

chromaoffset integer (encoding,video)

Set chroma qp offset from luma.

trellis integer (encoding,audio,video)

Set rate-distortion optimal quantization.

sc_factor integer (encoding,video)

Set value multiplied by qscale for each frame and added to scene_change_score.

mv0_threshold integer (encoding,video)

b_sensitivity integer (encoding,video)

Adjust sensitivity of b_frame_strategy 1.

compression_level integer (encoding,audio,video)

min_prediction_order integer (encoding,audio)

max_prediction_order integer (encoding,audio)

timecode_frame_start integer (encoding,video)

Set

GOP

timecode frame start number, in non drop frame format.

request_channels integer (decoding,audio)

Set desired number of audio channels.

bits_per_raw_sample integer

channel_layout integer (decoding/encoding,audio)

Possible values:

request_channel_layout integer (decoding,audio)

Possible values:

rc_max_vbv_use float (encoding,video)

rc_min_vbv_use float (encoding,video)

ticks_per_frame integer (decoding/encoding,audio,video)

color_primaries integer (decoding/encoding,video)

color_trc integer (decoding/encoding,video)

colorspace integer (decoding/encoding,video)

color_range integer (decoding/encoding,video)

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

chroma_sample_location integer (decoding/encoding,video)

log_level_offset integer

Set the log level offset.

slices integer (encoding,video)

Number of slices, used in parallelized encoding.

thread_type flags (decoding/encoding,video)

Select which multithreading methods to use.

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

Possible values:

slice

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

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

frame

Decode more than one frame at once.

Default value is slice+frame.

audio_service_type integer (encoding,audio)

Set audio service type.

Possible values:

ma

Main Audio Service

ef

Effects

vi

Visually Impaired

hi

Hearing Impaired

di

Dialogue

co

Commentary

em

Emergency

vo

Voice Over

ka

Karaoke

request_sample_fmt sample_fmt (decoding,audio)

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

pkt_timebase rational number

sub_charenc encoding (decoding,subtitles)

Set the input subtitles character encoding.

field_order field_order (video)

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

progressive

Progressive video

tt

Interlaced video, top field coded and displayed first

bb

Interlaced video, bottom field coded and displayed first

tb

Interlaced video, top coded first, bottom displayed first

bt

Interlaced video, bottom coded first, top displayed first

skip_alpha integer (decoding,video)

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

codec_whitelist list (input)

``,'' separated List of allowed decoders. By default all are allowed.

dump_separator string (input)

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

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

DECODERS

Decoders are configured elements in FFmpeg which allow the decoding of multimedia streams.

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

You can disable all the decoders with the configure option "--disable-decoders" and selectively enable / disable single decoders with the options "--enable-decoder=DECODER" / "--disable-decoder=DECODER".

The option "-decoders" of the ff* tools will display the list of enabled decoders.

VIDEO DECODERS

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

hevc

decoder.

Note: the skip_loop_filter option has effect only at level "all".

rawvideo

Raw video decoder.

This decoder decodes rawvideo streams.

Options

top top_field_first

Specify the assumed field type of the input video.

-1

the video is assumed to be progressive (default)

0

bottom-field-first is assumed

1

top-field-first is assumed

AUDIO DECODERS

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

ac3

audio decoder.

This decoder implements part of

and as well as the undocumented RealAudio 3 (a.k.a. dnet).

Decoder Options

-drc_scale value

Dynamic Range Scale Factor. The factor to apply to dynamic range values from the

AC-3

stream. This factor is applied exponentially. There are 3 notable scale factor ranges:

drc_scale == 0

DRC

disabled. Produces full range audio.

0 < drc_scale <= 1

DRC

enabled. Applies a fraction of the stream

DRC

value. Audio reproduction is between full range and full compression.

drc_scale > 1

DRC

enabled. Applies drc_scale asymmetrically. Loud sounds are fully compressed. Soft sounds are enhanced.

flac

audio decoder.

This decoder aims to implement the complete

specification from Xiph.

Decoder options

-use_buggy_lpc

The lavc

FLAC

encoder used to produce buggy streams with high lpc values (like the default value). This option makes it possible to decode such streams correctly by using lavc's old buggy lpc logic for decoding.

ffwavesynth

Internal wave synthetizer.

This decoder generates wave patterns according to predefined sequences. Its use is purely internal and the format of the data it accepts is not publicly documented.

libcelt

libcelt decoder wrapper.

libcelt allows libavcodec to decode the Xiph

ultra-low delay audio codec. Requires the presence of the libcelt headers and library during configuration. You need to explicitly configure the build with "--enable-libcelt".

libgsm

libgsm decoder wrapper.

libgsm allows libavcodec to decode the

full rate audio codec. Requires the presence of the libgsm headers and library during configuration. You need to explicitly configure the build with "--enable-libgsm".

This decoder supports both the ordinary

and the Microsoft variant.

libilbc

libilbc decoder wrapper.

libilbc allows libavcodec to decode the Internet Low Bitrate Codec (iLBC) audio codec. Requires the presence of the libilbc headers and library during configuration. You need to explicitly configure the build with "--enable-libilbc".

Options

The following option is supported by the libilbc wrapper.

enhance

Enable the enhancement of the decoded audio when set to 1. The default value is 0 (disabled).

libopencore-amrnb

libopencore-amrnb decoder wrapper.

libopencore-amrnb allows libavcodec to decode the Adaptive Multi-Rate Narrowband audio codec. Using it requires the presence of the libopencore-amrnb headers and library during configuration. You need to explicitly configure the build with "--enable-libopencore-amrnb".

An FFmpeg native decoder for AMR-NB exists, so users can decode AMR-NB without this library.

libopencore-amrwb

libopencore-amrwb decoder wrapper.

libopencore-amrwb allows libavcodec to decode the Adaptive Multi-Rate Wideband audio codec. Using it requires the presence of the libopencore-amrwb headers and library during configuration. You need to explicitly configure the build with "--enable-libopencore-amrwb".

An FFmpeg native decoder for AMR-WB exists, so users can decode AMR-WB without this library.

libopus

libopus decoder wrapper.

libopus allows libavcodec to decode the Opus Interactive Audio Codec. Requires the presence of the libopus headers and library during configuration. You need to explicitly configure the build with "--enable-libopus".

An FFmpeg native decoder for Opus exists, so users can decode Opus without this library.

SUBTITLES DECODERS

dvbsub

Options

compute_clut

-1

Compute clut if no matching

CLUT

is in the stream.

0

Never compute

CLUT

1

Always compute

CLUT

and override the one provided in the stream.

dvb_substream

Selects the dvb substream, or all substreams if -1 which is default.

dvdsub

This codec decodes the bitmap subtitles used in DVDs; the same subtitles can also be found in VobSub file pairs and in some Matroska files.

Options

palette

Specify the global palette used by the bitmaps. When stored in VobSub, the palette is normally specified in the index file; in Matroska, the palette is stored in the codec extra-data in the same format as in VobSub. In DVDs, the palette is stored in the

IFO

file, and therefore not available when reading from dumped

VOB

files.

The format for this option is a string containing 16 24-bits hexadecimal numbers (without 0x prefix) separated by comas, for example "0d00ee, ee450d, 101010, eaeaea, 0ce60b, ec14ed, ebff0b, 0d617a, 7b7b7b, d1d1d1, 7b2a0e, 0d950c, 0f007b, cf0dec, cfa80c, 7c127b".

ifo_palette

Specify the

IFO

file from which the global palette is obtained. (experimental)

forced_subs_only

Only decode subtitle entries marked as forced. Some titles have forced and non-forced subtitles in the same track. Setting this flag to 1 will only keep the forced subtitles. Default value is 0.

libzvbi-teletext

Libzvbi allows libavcodec to decode teletext pages and teletext subtitles. Requires the presence of the libzvbi headers and library during configuration. You need to explicitly configure the build with "--enable-libzvbi".

Options

txt_page

List of teletext page numbers to decode. You may use the special * string to match all pages. Pages that do not match the specified list are dropped. Default value is *.

txt_chop_top

Discards the top teletext line. Default value is 1.

txt_format

Specifies the format of the decoded subtitles. The teletext decoder is capable of decoding the teletext pages to bitmaps or to simple text, you should use ``bitmap'' for teletext pages, because certain graphics and colors cannot be expressed in simple text. You might use ``text'' for teletext based subtitles if your application can handle simple text based subtitles. Default value is bitmap.

txt_left

X offset of generated bitmaps, default is 0.

txt_top

Y offset of generated bitmaps, default is 0.

txt_chop_spaces

Chops leading and trailing spaces and removes empty lines from the generated text. This option is useful for teletext based subtitles where empty spaces may be present at the start or at the end of the lines or empty lines may be present between the subtitle lines because of double-sized teletext charactes. Default value is 1.

txt_duration

Sets the display duration of the decoded teletext pages or subtitles in miliseconds. Default value is 30000 which is 30 seconds.

txt_transparent

Force transparent background of the generated teletext bitmaps. Default value is 0 which means an opaque (black) background.

ENCODERS

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

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

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

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

AUDIO ENCODERS

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

aac

Advanced Audio Coding () encoder.

This encoder is an experimental FFmpeg-native

encoder. Currently only the low complexity (AAC-LC) profile is supported. To use this encoder, you must set strict option to experimental or lower.

As this encoder is experimental, unexpected behavior may exist from time to time. For a more stable

encoder, see libvo-aacenc. However, be warned that it has a worse quality reported by some users.

See also libfdk_aac.

Options

b

Set bit rate in bits/s. Setting this automatically activates constant bit rate (

CBR

) mode.

q

Set quality for variable bit rate (

VBR

) mode. This option is valid only using the ffmpeg command-line tool. For library interface users, use global_quality.

stereo_mode

Set stereo encoding mode. Possible values:

auto

Automatically selected by the encoder.

ms_off

Disable middle/side encoding. This is the default.

ms_force

Force middle/side encoding.

aac_coder

Set

AAC

encoder coding method. Possible values:

faac

FAAC-inspired method.

This method is a simplified reimplementation of the method used in

FAAC,

which sets thresholds proportional to the band energies, and then decreases all the thresholds with quantizer steps to find the appropriate quantization with distortion below threshold band by band.

The quality of this method is comparable to the two loop searching method described below, but somewhat a little better and slower.

anmr

Average noise to mask ratio (

ANMR

) trellis-based solution.

This has a theoretic best quality out of all the coding methods, but at the cost of the slowest speed.

twoloop

Two loop searching (

TLS

) method.

This method first sets quantizers depending on band thresholds and then tries to find an optimal combination by adding or subtracting a specific value from all quantizers and adjusting some individual quantizer a little.

This method produces similar quality with the

FAAC

method and is the default.

fast

Constant quantizer method.

This method sets a constant quantizer for all bands. This is the fastest of all the methods, yet produces the worst quality.

ac3 and ac3_fixed

audio encoders.

These encoders implement part of

and as well as the undocumented RealAudio 3 (a.k.a. dnet).

The ac3 encoder uses floating-point math, while the ac3_fixed encoder only uses fixed-point integer math. This does not mean that one is always faster, just that one or the other may be better suited to a particular system. The floating-point encoder will generally produce better quality audio for a given bitrate. The ac3_fixed encoder is not the default codec for any of the output formats, so it must be specified explicitly using the option "-acodec ac3_fixed" in order to use it.

Metadata

The

metadata options are used to set parameters that describe the audio, but in most cases do not affect the audio encoding itself. Some of the options do directly affect or influence the decoding and playback of the resulting bitstream, while others are just for informational purposes. A few of the options will add bits to the output stream that could otherwise be used for audio data, and will thus affect the quality of the output. Those will be indicated accordingly with a note in the option list below.

These parameters are described in detail in several publicly-available documents.

*<<www.atsc.org/cms/standards/a_52-2010.pdf>>

*<<www.atsc.org/cms/standards/a_54a_with_corr_1.pdf>>

*<<www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/18_Metadata.Guide.pdf>>

*<<www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/46_DDEncodingGuidelines.pdf>>

Metadata Control Options

-per_frame_metadata boolean

Allow Per-Frame Metadata. Specifies if the encoder should check for changing metadata for each frame.

0

The metadata values set at initialization will be used for every frame in the stream. (default)

1

Metadata values can be changed before encoding each frame.

Downmix Levels

-center_mixlev level

Center Mix Level. The amount of gain the decoder should apply to the center channel when downmixing to stereo. This field will only be written to the bitstream if a center channel is present. The value is specified as a scale factor. There are 3 valid values:

0.707

Apply -3dB gain

0.595

Apply -4.5dB gain (default)

0.500

Apply -6dB gain

-surround_mixlev level

Surround Mix Level. The amount of gain the decoder should apply to the surround channel(s) when downmixing to stereo. This field will only be written to the bitstream if one or more surround channels are present. The value is specified as a scale factor. There are 3 valid values:

0.707

Apply -3dB gain

0.500

Apply -6dB gain (default)

0.000

Silence Surround Channel(s)

Audio Production Information

Audio Production Information is optional information describing the mixing environment. Either none or both of the fields are written to the bitstream.

-mixing_level number

Mixing Level. Specifies peak sound pressure level (

SPL

) in the production environment when the mix was mastered. Valid values are 80 to 111, or -1 for unknown or not indicated. The default value is -1, but that value cannot be used if the Audio Production Information is written to the bitstream. Therefore, if the "room_type" option is not the default value, the "mixing_level" option must not be -1.

-room_type type

Room Type. Describes the equalization used during the final mixing session at the studio or on the dubbing stage. A large room is a dubbing stage with the industry standard X-curve equalization; a small room has flat equalization. This field will not be written to the bitstream if both the "mixing_level" option and the "room_type" option have the default values.

0

notindicated

Not Indicated (default)

1

large

Large Room

2

small

Small Room

Other Metadata Options

-copyright boolean

Copyright Indicator. Specifies whether a copyright exists for this audio.

0

off

No Copyright Exists (default)

1

on

Copyright Exists

-dialnorm value

Dialogue Normalization. Indicates how far the average dialogue level of the program is below digital 100% full scale (0 dBFS). This parameter determines a level shift during audio reproduction that sets the average volume of the dialogue to a preset level. The goal is to match volume level between program sources. A value of -31dB will result in no volume level change, relative to the source volume, during audio reproduction. Valid values are whole numbers in the range -31 to -1, with -31 being the default.

-dsur_mode mode

Dolby Surround Mode. Specifies whether the stereo signal uses Dolby Surround (Pro Logic). This field will only be written to the bitstream if the audio stream is stereo. Using this option does

NOT

mean the encoder will actually apply Dolby Surround processing.

0

notindicated

Not Indicated (default)

1

off

Not Dolby Surround Encoded

2

on

Dolby Surround Encoded

-original boolean

Original Bit Stream Indicator. Specifies whether this audio is from the original source and not a copy.

0

off

Not Original Source

1

on

Original Source (default)

Extended Bitstream Information

The extended bitstream options are part of the Alternate Bit Stream Syntax as specified in Annex D of the A/52:2010 standard. It is grouped into 2 parts. If any one parameter in a group is specified, all values in that group will be written to the bitstream. Default values are used for those that are written but have not been specified. If the mixing levels are written, the decoder will use these values instead of the ones specified in the "center_mixlev" and "surround_mixlev" options if it supports the Alternate Bit Stream Syntax.

Extended Bitstream Information - Part 1

-dmix_mode mode

Preferred Stereo Downmix Mode. Allows the user to select either Lt/Rt (Dolby Surround) or Lo/Ro (normal stereo) as the preferred stereo downmix mode.

0

notindicated

Not Indicated (default)

1

ltrt

Lt/Rt Downmix Preferred

2

loro

Lo/Ro Downmix Preferred

-ltrt_cmixlev level

Lt/Rt Center Mix Level. The amount of gain the decoder should apply to the center channel when downmixing to stereo in Lt/Rt mode.

1.414

Apply +3dB gain

1.189

Apply +1.5dB gain

1.000

Apply 0dB gain

0.841

Apply -1.5dB gain

0.707

Apply -3.0dB gain

0.595

Apply -4.5dB gain (default)

0.500

Apply -6.0dB gain

0.000

Silence Center Channel

-ltrt_surmixlev level

Lt/Rt Surround Mix Level. The amount of gain the decoder should apply to the surround channel(s) when downmixing to stereo in Lt/Rt mode.

0.841

Apply -1.5dB gain

0.707

Apply -3.0dB gain

0.595

Apply -4.5dB gain

0.500

Apply -6.0dB gain (default)

0.000

Silence Surround Channel(s)

-loro_cmixlev level

Lo/Ro Center Mix Level. The amount of gain the decoder should apply to the center channel when downmixing to stereo in Lo/Ro mode.

1.414

Apply +3dB gain

1.189

Apply +1.5dB gain

1.000

Apply 0dB gain

0.841

Apply -1.5dB gain

0.707

Apply -3.0dB gain

0.595

Apply -4.5dB gain (default)

0.500

Apply -6.0dB gain

0.000

Silence Center Channel

-loro_surmixlev level

Lo/Ro Surround Mix Level. The amount of gain the decoder should apply to the surround channel(s) when downmixing to stereo in Lo/Ro mode.

0.841

Apply -1.5dB gain

0.707

Apply -3.0dB gain

0.595

Apply -4.5dB gain

0.500

Apply -6.0dB gain (default)

0.000

Silence Surround Channel(s)

Extended Bitstream Information - Part 2

-dsurex_mode mode

Dolby Surround

EX

Mode. Indicates whether the stream uses Dolby Surround

EX

(7.1 matrixed to 5.1). Using this option does

NOT

mean the encoder will actually apply Dolby Surround

EX

processing.

0

notindicated

Not Indicated (default)

1

on

Dolby Surround

EX

Off

2

off

Dolby Surround

EX

On

-dheadphone_mode mode

Dolby Headphone Mode. Indicates whether the stream uses Dolby Headphone encoding (multi-channel matrixed to 2.0 for use with headphones). Using this option does

NOT

mean the encoder will actually apply Dolby Headphone processing.

0

notindicated

Not Indicated (default)

1

on

Dolby Headphone Off

2

off

Dolby Headphone On

-ad_conv_type type

A/D Converter Type. Indicates whether the audio has passed through

HDCD A/D

conversion.

0

standard

Standard A/D Converter (default)

1

hdcd

HDCD A/D

Converter

Other

Encoding Options

-stereo_rematrixing boolean

Stereo Rematrixing. Enables/Disables use of rematrixing for stereo input. This is an optional

AC-3

feature that increases quality by selectively encoding the left/right channels as mid/side. This option is enabled by default, and it is highly recommended that it be left as enabled except for testing purposes.

Floating-Point-Only

Encoding Options

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

-channel_coupling boolean

Enables/Disables use of channel coupling, which is an optional

AC-3

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

-1

auto

Selected by Encoder (default)

0

off

Disable Channel Coupling

1

on

Enable Channel Coupling

-cpl_start_band number

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

-1

auto

Selected by Encoder (default)

flac

(Free Lossless Audio Codec) Encoder

Options

The following options are supported by FFmpeg's flac encoder.

compression_level

Sets the compression level, which chooses defaults for many other options if they are not set explicitly.

frame_size

Sets the size of the frames in samples per channel.

lpc_coeff_precision

Sets the

LPC

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

lpc_type

Sets the first stage

LPC

algorithm

none

LPC

is not used

fixed

fixed

LPC

coefficients

levinson

cholesky

lpc_passes

Number of passes to use for Cholesky factorization during

LPC

analysis

min_partition_order

The minimum partition order

max_partition_order

The maximum partition order

prediction_order_method

estimation

2level

4level

8level

search

Bruteforce search

log

ch_mode

Channel mode

auto

The mode is chosen automatically for each frame

indep

Chanels are independently coded

left_side

right_side

mid_side

exact_rice_parameters

Chooses if rice parameters are calculated exactly or approximately. if set to 1 then they are chosen exactly, which slows the code down slightly and improves compression slightly.

multi_dim_quant

Multi Dimensional Quantization. If set to 1 then a 2nd stage

LPC

algorithm is applied after the first stage to finetune the coefficients. This is quite slow and slightly improves compression.

libfaac

libfaac (Advanced Audio Coding) encoder wrapper.

Requires the presence of the libfaac headers and library during configuration. You need to explicitly configure the build with "--enable-libfaac --enable-nonfree".

This encoder is considered to be of higher quality with respect to the the native experimental FFmpeg

encoder.

For more information see the libfaac project at <www.audiocoding.com/faac.html>.

Options

The following shared FFmpeg codec options are recognized.

The following options are supported by the libfaac wrapper. The faac-equivalent of the options are listed in parentheses.

b (-b)

Set bit rate in bits/s for

ABR

(Average Bit Rate) mode. If the bit rate is not explicitly specified, it is automatically set to a suitable value depending on the selected profile. faac bitrate is expressed in kilobits/s.

Note that libfaac does not support

CBR

(Constant Bit Rate) but only

ABR

(Average Bit Rate).

If

VBR

mode is enabled this option is ignored.

ar (-R)

Set audio sampling rate (in Hz).

ac (-c)

Set the number of audio channels.

cutoff (-C)

Set cutoff frequency. If not specified (or explicitly set to 0) it will use a value automatically computed by the library. Default value is 0.

profile

Set audio profile.

The following profiles are recognized:

aac_main

Main

AAC

(Main)

aac_low

Low Complexity

AAC

(

LC

)

aac_ssr

Scalable Sample Rate (

SSR

)

aac_ltp

Long Term Prediction (

LTP

)

If not specified it is set to aac_low.

flags +qscale

Set constant quality

VBR

(Variable Bit Rate) mode.

global_quality

Set quality in

VBR

mode as an integer number of lambda units.

Only relevant when

VBR

mode is enabled with "flags +qscale". The value is converted to

QP

units by dividing it by "FF_QP2LAMBDA", and used to set the quality value used by libfaac. A reasonable range for the option value in

QP

units is [10-500], the higher the value the higher the quality.

q (-q)

Enable

VBR

mode when set to a non-negative value, and set constant quality value as a double floating point value in

QP

units.

The value sets the quality value used by libfaac. A reasonable range for the option value is [10-500], the higher the value the higher the quality.

This option is valid only using the ffmpeg command-line tool. For library interface users, use global_quality.

Examples

*

Use ffmpeg to convert an audio file to

ABR 128

kbps

AAC

in an M4A (

MP4

) container:

        ffmpeg -i input.wav -codec:a libfaac -b:a 128k -output.m4a

*

Use ffmpeg to convert an audio file to

VBR AAC,

using the

LTP AAC

profile:

        ffmpeg -i input.wav -c:a libfaac -profile:a aac_ltp -q:a 100 output.m4a

libfdk_aac

libfdk-aac (Advanced Audio Coding) encoder wrapper.

The libfdk-aac library is based on the Fraunhofer

code from the Android project.

Requires the presence of the libfdk-aac headers and library during configuration. You need to explicitly configure the build with "--enable-libfdk-aac". The library is also incompatible with

so if you allow the use of you should configure with "--enable-gpl --enable-nonfree --enable-libfdk-aac".

This encoder is considered to be of higher quality with respect to both the native experimental FFmpeg

encoder and libfaac.

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

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

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

Options

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

b

Set bit rate in bits/s. If the bitrate is not explicitly specified, it is automatically set to a suitable value depending on the selected profile.

In case

VBR

mode is enabled the option is ignored.

ar

Set audio sampling rate (in Hz).

channels

Set the number of audio channels.

flags +qscale

Enable fixed quality,

VBR

(Variable Bit Rate) mode. Note that

VBR

is implicitly enabled when the vbr value is positive.

cutoff

Set cutoff frequency. If not specified (or explicitly set to 0) it will use a value automatically computed by the library. Default value is 0.

profile

Set audio profile.

The following profiles are recognized:

aac_low

Low Complexity

AAC

(

LC

)

aac_he

High Efficiency

AAC

(HE-AAC)

aac_he_v2

High Efficiency

AAC

version 2 (HE-AACv2)

aac_ld

Low Delay

AAC

(

LD

)

aac_eld

Enhanced Low Delay

AAC

(

ELD

)

If not specified it is set to aac_low.

The following are private options of the libfdk_aac encoder.

afterburner

Enable afterburner feature if set to 1, disabled if set to 0. This improves the quality but also the required processing power.

Default value is 1.

eld_sbr

Enable

SBR

(Spectral Band Replication) for

ELD

if set to 1, disabled if set to 0.

Default value is 0.

signaling

Set

SBR/PS

signaling style.

It can assume one of the following values:

default

choose signaling implicitly (explicit hierarchical by default, implicit if global header is disabled)

implicit

implicit backwards compatible signaling

explicit_sbr

explicit

SBR,

implicit

PS

signaling

explicit_hierarchical

explicit hierarchical signaling

Default value is default.

latm

Output

LATM/LOAS

encapsulated data if set to 1, disabled if set to 0.

Default value is 0.

header_period

Set StreamMuxConfig and

PCE

repetition period (in frames) for sending in-band configuration buffers within

LATM/LOAS

transport layer.

Must be a 16-bits non-negative integer.

Default value is 0.

vbr

Set

VBR

mode, from 1 to 5. 1 is lowest quality (though still pretty good) and 5 is highest quality. A value of 0 will disable

VBR,

and

CBR

(Constant Bit Rate) is enabled.

Currently only the aac_low profile supports

VBR

encoding.

VBR

modes 1-5 correspond to roughly the following average bit rates:

1

32 kbps/channel

2

40 kbps/channel

3

48-56 kbps/channel

4

64 kbps/channel

5

about 80-96 kbps/channel

Default value is 0.

Examples

*

Use ffmpeg to convert an audio file to

VBR AAC

in an M4A (

MP4

) container:

        ffmpeg -i input.wav -codec:a libfdk_aac -vbr 3 output.m4a

*

Use ffmpeg to convert an audio file to

CBR

64k kbps

AAC,

using the High-Efficiency

AAC

profile:

        ffmpeg -i input.wav -c:a libfdk_aac -profile:a aac_he -b:a 64k output.m4a

libmp3lame

(Lame Ain't an Encoder) encoder wrapper.

Requires the presence of the libmp3lame headers and library during configuration. You need to explicitly configure the build with "--enable-libmp3lame".

See libshine for a fixed-point

encoder, although with a lower quality.

Options

The following options are supported by the libmp3lame wrapper. The lame-equivalent of the options are listed in parentheses.

b (-b)

Set bitrate expressed in bits/s for

CBR

or

ABR. LAME

"bitrate" is expressed in kilobits/s.

q (-V)

Set constant quality setting for

VBR.

This option is valid only using the ffmpeg command-line tool. For library interface users, use global_quality.

compression_level (-q)

Set algorithm quality. Valid arguments are integers in the 0-9 range, with 0 meaning highest quality but slowest, and 9 meaning fastest while producing the worst quality.

reservoir

Enable use of bit reservoir when set to 1. Default value is 1.

LAME

has this enabled by default, but can be overridden by use --nores option.

joint_stereo (-m j)

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

abr (--abr)

Enable the encoder to use

ABR

when set to 1. The lame --abr sets the target bitrate, while this options only tells FFmpeg to use

ABR

still relies on b to set bitrate.

libopencore-amrnb

OpenCORE Adaptive Multi-Rate Narrowband encoder.

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

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

Options

b

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

4750

5150

5900

6700

7400

7950

10200

12200

dtx

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

libshine

Shine Fixed-Point encoder wrapper.

Shine is a fixed-point

encoder. It has a far better performance on platforms without an e.g. armel CPUs, and some phones and tablets. However, as it is more targeted on performance than quality, it is not on par with and other production-grade encoders quality-wise. Also, according to the project's homepage, this encoder may not be free of bugs as the code was written a long time ago and the project was dead for at least 5 years.

This encoder only supports stereo and mono input. This is also CBR-only.

The original project (last updated in early 2007) is at <sourceforge.net/projects/libshine-fxp>. We only support the updated fork by the Savonet/Liquidsoap project at <github.com/savonet/shine>.

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

See also libmp3lame.

Options

The following options are supported by the libshine wrapper. The shineenc-equivalent of the options are listed in parentheses.

b (-b)

Set bitrate expressed in bits/s for

CBR.

shineenc -b option is expressed in kilobits/s.

libtwolame

TwoLAME encoder wrapper.

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

Options

The following options are supported by the libtwolame wrapper. The twolame-equivalent options follow the FFmpeg ones and are in parentheses.

b (-b)

Set bitrate expressed in bits/s for

CBR.

twolame b option is expressed in kilobits/s. Default value is 128k.

q (-V)

Set quality for experimental

VBR

support. Maximum value range is from -50 to 50, useful range is from -10 to 10. The higher the value, the better the quality. This option is valid only using the ffmpeg command-line tool. For library interface users, use global_quality.

mode (--mode)

Set the mode of the resulting audio. Possible values:

auto

Choose mode automatically based on the input. This is the default.

stereo

Stereo

joint_stereo

Joint stereo

dual_channel

Dual channel

mono

Mono

psymodel (--psyc-mode)

Set psychoacoustic model to use in encoding. The argument must be an integer between -1 and 4, inclusive. The higher the value, the better the quality. The default value is 3.

energy_levels (--energy)

Enable energy levels extensions when set to 1. The default value is 0 (disabled).

error_protection (--protect)

Enable

CRC

error protection when set to 1. The default value is 0 (disabled).

copyright (--copyright)

Set

MPEG

audio copyright flag when set to 1. The default value is 0 (disabled).

original (--original)

Set

MPEG

audio original flag when set to 1. The default value is 0 (disabled).

libvo-aacenc

VisualOn encoder.

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

This encoder is considered to be worse than the native experimental FFmpeg

encoder, according to multiple sources.

Options

The VisualOn

encoder only support encoding AAC-LC and up to 2 channels. It is also CBR-only.

b

Set bit rate in bits/s.

libvo-amrwbenc

VisualOn Adaptive Multi-Rate Wideband encoder.

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

This is a mono-only encoder. Officially it only supports 16000Hz sample rate, but you can override it by setting strict to unofficial or lower.

Options

b

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

6600

8850

12650

14250

15850

18250

19850

23050

23850

dtx

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

libopus

libopus Opus Interactive Audio Codec encoder wrapper.

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

Option Mapping

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

b (bitrate)

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

vbr (vbr, hard-cbr, and cvbr)

Set

VBR

mode. The FFmpeg vbr option has the following valid arguments, with the their opusenc equivalent options in parentheses:

off (hard-cbr)

Use constant bit rate encoding.

on (vbr)

Use variable bit rate encoding (the default).

constrained (cvbr)

Use constrained variable bit rate encoding.

compression_level (comp)

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

frame_duration (framesize)

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

packet_loss (expect-loss)

Set expected packet loss percentage. The default is 0.

application (N.A.)

Set intended application type. Valid options are listed below:

voip

Favor improved speech intelligibility.

audio

Favor faithfulness to the input (the default).

lowdelay

Restrict to only the lowest delay modes.

cutoff (N.A.)

Set cutoff bandwidth in Hz. The argument must be exactly one of the following: 4000, 6000, 8000, 12000, or 20000, corresponding to narrowband, mediumband, wideband, super wideband, and fullband respectively. The default is 0 (cutoff disabled).

libvorbis

libvorbis encoder wrapper.

Requires the presence of the libvorbisenc headers and library during configuration. You need to explicitly configure the build with "--enable-libvorbis".

Options

The following options are supported by the libvorbis wrapper. The oggenc-equivalent of the options are listed in parentheses.

To get a more accurate and extensive documentation of the libvorbis options, consult the libvorbisenc's and oggenc's documentations. See <xiph.org/vorbis>, <wiki.xiph.org/Vorbis-tools>, and oggenc(1).

b (-b)

Set bitrate expressed in bits/s for

ABR.

oggenc -b is expressed in kilobits/s.

q (-q)

Set constant quality setting for

VBR.

The value should be a float number in the range of -1.0 to 10.0. The higher the value, the better the quality. The default value is 3.0.

This option is valid only using the ffmpeg command-line tool. For library interface users, use global_quality.

cutoff (--advanced-encode-option lowpass_frequency=N)

Set cutoff bandwidth in Hz, a value of 0 disables cutoff. oggenc's related option is expressed in kHz. The default value is 0 (cutoff disabled).

minrate (-m)

Set minimum bitrate expressed in bits/s. oggenc -m is expressed in kilobits/s.

maxrate (-M)

Set maximum bitrate expressed in bits/s. oggenc -M is expressed in kilobits/s. This only has effect on

ABR

mode.

iblock (--advanced-encode-option impulse_noisetune=N)

Set noise floor bias for impulse blocks. The value is a float number from -15.0 to 0.0. A negative bias instructs the encoder to pay special attention to the crispness of transients in the encoded audio. The tradeoff for better transient response is a higher bitrate.

libwavpack

A wrapper providing WavPack encoding through libwavpack.

Only lossless mode using 32-bit integer samples is supported currently.

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

Note that a libavcodec-native encoder for the WavPack codec exists so users can encode audios with this codec without using this encoder. See wavpackenc.

Options

wavpack command line utility's corresponding options are listed in parentheses, if any.

frame_size (--blocksize)

Default is 32768.

compression_level

Set speed vs. compression tradeoff. Acceptable arguments are listed below:

0 (-f)

Fast mode.

1

Normal (default) settings.

2 (-h)

High quality.

3 (-hh)

Very high quality.

4-8 (-hh -x

EXTRAPROC

)

Same as 3, but with extra processing enabled.

4 is the same as -x2 and 8 is the same as -x6.

wavpack

WavPack lossless audio encoder.

This is a libavcodec-native WavPack encoder. There is also an encoder based on libwavpack, but there is virtually no reason to use that encoder.

See also libwavpack.

Options

The equivalent options for wavpack command line utility are listed in parentheses.

Shared options

The following shared options are effective for this encoder. Only special notes about this particular encoder will be documented here. For the general meaning of the options, see the Codec Options chapter.

frame_size (--blocksize)

For this encoder, the range for this option is between 128 and 131072. Default is automatically decided based on sample rate and number of channel.

For the complete formula of calculating default, see libavcodec/wavpackenc.c.

compression_level (-f, -h, -hh, and -x)

This option's syntax is consistent with libwavpack's.

Private options

joint_stereo (-j)

Set whether to enable joint stereo. Valid values are:

on (1)

Force mid/side audio encoding.

off (0)

Force left/right audio encoding.

auto

Let the encoder decide automatically.

optimize_mono

Set whether to enable optimization for mono. This option is only effective for non-mono streams. Available values:

on

enabled

off

disabled

VIDEO ENCODERS

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

jpeg2000

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

Options

format

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

snow

Options

iterative_dia_size

dia size for the iterative motion estimation

libtheora

libtheora Theora encoder wrapper.

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

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

Options

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

b

Set the video bitrate in bit/s for

CBR

(Constant Bit Rate) mode. In case

VBR

(Variable Bit Rate) mode is enabled this option is ignored.

flags

Used to enable constant quality mode (

VBR

) encoding through the qscale flag, and to enable the "pass1" and "pass2" modes.

g

Set the

GOP

size.

global_quality

Set the global quality as an integer in lambda units.

Only relevant when

VBR

mode is enabled with "flags +qscale". The value is converted to

QP

units by dividing it by "FF_QP2LAMBDA", clipped in the [0 - 10] range, and then multiplied by 6.3 to get a value in the native libtheora range [0-63]. A higher value corresponds to a higher quality.

q

Enable

VBR

mode when set to a non-negative value, and set constant quality value as a double floating point value in

QP

units.

The value is clipped in the [0-10] range, and then multiplied by 6.3 to get a value in the native libtheora range [0-63].

This option is valid only using the ffmpeg command-line tool. For library interface users, use global_quality.

Examples

*

Set maximum constant quality (

VBR

) encoding with ffmpeg:

        ffmpeg -i INPUT -codec:v libtheora -q:v 10 OUTPUT.ogg

*

Use ffmpeg to convert a

CBR 1000

kbps Theora video stream:

        ffmpeg -i INPUT -codec:v libtheora -b:v 1000k OUTPUT.ogg

libvpx

format supported through libvpx.

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

Options

The following options are supported by the libvpx wrapper. The vpxenc-equivalent options or values are listed in parentheses for easy migration.

To reduce the duplication of documentation, only the private options and some others requiring special attention are documented here. For the documentation of the undocumented generic options, see the Codec Options chapter.

To get more documentation of the libvpx options, invoke the command ffmpeg -h encoder=libvpx, ffmpeg -h encoder=libvpx-vp9 or vpxenc --help. Further information is available in the libvpx

documentation.

b (target-bitrate)

Set bitrate in bits/s. Note that FFmpeg's b option is expressed in bits/s, while vpxenc's target-bitrate is in kilobits/s.

g (kf-max-dist)

keyint_min (kf-min-dist)

qmin (min-q)

qmax (max-q)

bufsize (buf-sz, buf-optimal-sz)

Set ratecontrol buffer size (in bits). Note vpxenc's options are specified in milliseconds, the libvpx wrapper converts this value as follows: "buf-sz = bufsize * 1000 / bitrate", "buf-optimal-sz = bufsize * 1000 / bitrate * 5 / 6".

rc_init_occupancy (buf-initial-sz)

Set number of bits which should be loaded into the rc buffer before decoding starts. Note vpxenc's option is specified in milliseconds, the libvpx wrapper converts this value as follows: "rc_init_occupancy * 1000 / bitrate".

undershoot-pct

Set datarate undershoot (min) percentage of the target bitrate.

overshoot-pct

Set datarate overshoot (max) percentage of the target bitrate.

skip_threshold (drop-frame)

qcomp (bias-pct)

maxrate (maxsection-pct)

Set

GOP

max bitrate in bits/s. Note vpxenc's option is specified as a percentage of the target bitrate, the libvpx wrapper converts this value as follows: "(maxrate * 100 / bitrate)".

minrate (minsection-pct)

Set

GOP

min bitrate in bits/s. Note vpxenc's option is specified as a percentage of the target bitrate, the libvpx wrapper converts this value as follows: "(minrate * 100 / bitrate)".

minrate, maxrate, b end-usage=cbr

"(minrate == maxrate == bitrate)".

crf (end-usage=cq, cq-level)

quality, deadline (deadline)

best

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

good

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

realtime

Use realtime quality deadline.

speed, cpu-used (cpu-used)

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

nr (noise-sensitivity)

static-thresh

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

slices (token-parts)

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

max-intra-rate

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

force_key_frames

"VPX_EFLAG_FORCE_KF"

Alternate reference frame related

auto-alt-ref

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

arnr-max-frames

Set altref noise reduction max frame count.

arnr-type

Set altref noise reduction filter type: backward, forward, centered.

arnr-strength

Set altref noise reduction filter strength.

rc-lookahead, lag-in-frames (lag-in-frames)

Set number of frames to look ahead for frametype and ratecontrol.

error-resilient

Enable error resiliency features.

VP9-specific options

lossless

Enable lossless mode.

tile-columns

Set number of tile columns to use. Note this is given as "log2(tile_columns)". For example, 8 tile columns would be requested by setting the tile-columns option to 3.

tile-rows

Set number of tile rows to use. Note this is given as "log2(tile_rows)". For example, 4 tile rows would be requested by setting the tile-rows option to 2.

frame-parallel

Enable frame parallel decodability features.

aq-mode

Set adaptive quantization mode (0: off (default), 1: variance 2: complexity, 3: cyclic refresh).

colorspace color-space

Set input color space. The

VP9

bitstream supports signaling the following colorspaces:

rgb sRGB

bt709 bt709

unspecified unknown

bt470bg bt601

smpte170m smpte170

smpte240m smpte240

bt2020_ncl bt2020

For more information about libvpx see: <www.webmproject.org>

libwebp

libwebp WebP Image encoder wrapper

libwebp is Google's official encoder for WebP images. It can encode in either lossy or lossless mode. Lossy images are essentially a wrapper around a

frame. Lossless images are a separate codec developed by Google.

Pixel Format

Currently, libwebp only supports

for lossy and for lossless due to limitations of the format and libwebp. Alpha is supported for either mode. Because of limitations, if is passed in when encoding lossy or is passed in for encoding lossless, the pixel format will automatically be converted using functions from libwebp. This is not ideal and is done only for convenience.

Options

-lossless boolean

Enables/Disables use of lossless mode. Default is 0.

-compression_level integer

For lossy, this is a quality/speed tradeoff. Higher values give better quality for a given size at the cost of increased encoding time. For lossless, this is a size/speed tradeoff. Higher values give smaller size at the cost of increased encoding time. More specifically, it controls the number of extra algorithms and compression tools used, and varies the combination of these tools. This maps to the method option in libwebp. The valid range is 0 to 6. Default is 4.

-qscale float

For lossy encoding, this controls image quality, 0 to 100. For lossless encoding, this controls the effort and time spent at compressing more. The default value is 75. Note that for usage via libavcodec, this option is called global_quality and must be multiplied by

FF_QP2LAMBDA

.

-preset type

Configuration preset. This does some automatic settings based on the general type of the image.

none

Do not use a preset.

default

Use the encoder default.

picture

Digital picture, like portrait, inner shot

photo

Outdoor photograph, with natural lighting

drawing

Hand or line drawing, with high-contrast details

icon

Small-sized colorful images

text

Text-like

libx264, libx264rgb

x264 H.264/MPEG-4 encoder wrapper.

This encoder requires the presence of the libx264 headers and library during configuration. You need to explicitly configure the build with "--enable-libx264".

libx264 supports an impressive number of features, including 8x8 and 4x4 adaptive spatial transform, adaptive B-frame placement,

entropy coding, interlacing (), lossless mode, psy optimizations for detail retention (adaptive quantization, psy-RD, psy-trellis).

Many libx264 encoder options are mapped to FFmpeg global codec options, while unique encoder options are provided through private options. Additionally the x264opts and x264-params private options allows one to pass a list of key=value tuples as accepted by the libx264 "x264_param_parse" function.

The x264 project website is at <www.videolan.org/developers/x264.html>.

The libx264rgb encoder is the same as libx264, except it accepts packed

pixel formats as input instead of

Supported Pixel Formats

x264 supports 8- to 10-bit color spaces. The exact bit depth is controlled at x264's configure time. FFmpeg only supports one bit depth in one particular build. In other words, it is not possible to build one FFmpeg with multiple versions of x264 with different bit depths.

Options

The following options are supported by the libx264 wrapper. The x264-equivalent options or values are listed in parentheses for easy migration.

To reduce the duplication of documentation, only the private options and some others requiring special attention are documented here. For the documentation of the undocumented generic options, see the Codec Options chapter.

To get a more accurate and extensive documentation of the libx264 options, invoke the command x264 --full-help or consult the libx264 documentation.

b (bitrate)

Set bitrate in bits/s. Note that FFmpeg's b option is expressed in bits/s, while x264's bitrate is in kilobits/s.

bf (bframes)

g (keyint)

qmin (qpmin)

Minimum quantizer scale.

qmax (qpmax)

Maximum quantizer scale.

qdiff (qpstep)

Maximum difference between quantizer scales.

qblur (qblur)

Quantizer curve blur

qcomp (qcomp)

Quantizer curve compression factor

refs (ref)

Number of reference frames each P-frame can use. The range is from 0-16.

sc_threshold (scenecut)

Sets the threshold for the scene change detection.

trellis (trellis)

Performs Trellis quantization to increase efficiency. Enabled by default.

nr (nr)

me_range (merange)

Maximum range of the motion search in pixels.

me_method (me)

Set motion estimation method. Possible values in the decreasing order of speed:

dia (dia)

epzs (dia)

Diamond search with radius 1 (fastest). epzs is an alias for dia.

hex (hex)

Hexagonal search with radius 2.

umh (umh)

Uneven multi-hexagon search.

esa (esa)

Exhaustive search.

tesa (tesa)

Hadamard exhaustive search (slowest).

subq (subme)

Sub-pixel motion estimation method.

b_strategy (b-adapt)

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

keyint_min (min-keyint)

Minimum

GOP

size.

coder

Set entropy encoder. Possible values:

ac

Enable

CABAC.

vlc

Enable

CAVLC

and disable

CABAC.

It generates the same effect as x264's --no-cabac option.

cmp

Set full pixel motion estimation comparation algorithm. Possible values:

chroma

Enable chroma in motion estimation.

sad

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

threads (threads)

Number of encoding threads.

thread_type

Set multithreading technique. Possible values:

slice

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

frame

Frame-based multithreading.

flags

Set encoding flags. It can be used to disable closed

GOP

and enable open

GOP

by setting it to "-cgop". The result is similar to the behavior of x264's --open-gop option.

rc_init_occupancy (vbv-init)

preset (preset)

Set the encoding preset.

tune (tune)

Set tuning of the encoding params.

profile (profile)

Set profile restrictions.

fastfirstpass

Enable fast settings when encoding first pass, when set to 1. When set to 0, it has the same effect of x264's --slow-firstpass option.

crf (crf)

Set the quality for constant quality mode.

crf_max (crf-max)

In

CRF

mode, prevents

VBV

from lowering quality beyond this point.

qp (qp)

Set constant quantization rate control method parameter.

aq-mode (aq-mode)

Set

AQ

method. Possible values:

none (0)

Disabled.

variance (1)

Variance

AQ

(complexity mask).

autovariance (2)

Auto-variance

AQ

(experimental).

aq-strength (aq-strength)

Set

AQ

strength, reduce blocking and blurring in flat and textured areas.

psy

Use psychovisual optimizations when set to 1. When set to 0, it has the same effect as x264's --no-psy option.

psy-rd (psy-rd)

Set strength of psychovisual optimization, in psy-rd:psy-trellis format.

rc-lookahead (rc-lookahead)

Set number of frames to look ahead for frametype and ratecontrol.

weightb

Enable weighted prediction for B-frames when set to 1. When set to 0, it has the same effect as x264's --no-weightb option.

weightp (weightp)

Set weighted prediction method for P-frames. Possible values:

none (0)

Disabled

simple (1)

Enable only weighted refs

smart (2)

Enable both weighted refs and duplicates

ssim (ssim)

Enable calculation and printing

SSIM

stats after the encoding.

intra-refresh (intra-refresh)

Enable the use of Periodic Intra Refresh instead of

IDR

frames when set to 1.

avcintra-class (class)

Configure the encoder to generate AVC-Intra. Valid values are 50,100 and 200

bluray-compat (bluray-compat)

Configure the encoder to be compatible with the bluray standard. It is a shorthand for setting ``bluray-compat=1 force-cfr=1''.

b-bias (b-bias)

Set the influence on how often B-frames are used.

b-pyramid (b-pyramid)

Set method for keeping of some B-frames as references. Possible values:

none (none)

Disabled.

strict (strict)

Strictly hierarchical pyramid.

normal (normal)

Non-strict (not Blu-ray compatible).

mixed-refs

Enable the use of one reference per partition, as opposed to one reference per macroblock when set to 1. When set to 0, it has the same effect as x264's --no-mixed-refs option.

8x8dct

Enable adaptive spatial transform (high profile 8x8 transform) when set to 1. When set to 0, it has the same effect as x264's --no-8x8dct option.

fast-pskip

Enable early

SKIP

detection on P-frames when set to 1. When set to 0, it has the same effect as x264's --no-fast-pskip option.

aud (aud)

Enable use of access unit delimiters when set to 1.

mbtree

Enable use macroblock tree ratecontrol when set to 1. When set to 0, it has the same effect as x264's --no-mbtree option.

deblock (deblock)

Set loop filter parameters, in alpha:beta form.

cplxblur (cplxblur)

Set fluctuations reduction in

QP

(before curve compression).

partitions (partitions)

Set partitions to consider as a comma-separated list of. Possible values in the list:

p8x8

8x8 P-frame partition.

p4x4

4x4 P-frame partition.

b8x8

4x4 B-frame partition.

i8x8

8x8 I-frame partition.

i4x4

4x4 I-frame partition. (Enabling p4x4 requires p8x8 to be enabled. Enabling i8x8 requires adaptive spatial transform (8x8dct option) to be enabled.)

none (none)

Do not consider any partitions.

all (all)

Consider every partition.

direct-pred (direct)

Set direct

MV

prediction mode. Possible values:

none (none)

Disable

MV

prediction.

spatial (spatial)

Enable spatial predicting.

temporal (temporal)

Enable temporal predicting.

auto (auto)

Automatically decided.

slice-max-size (slice-max-size)

Set the limit of the size of each slice in bytes. If not specified but

RTP

payload size (ps) is specified, that is used.

stats (stats)

Set the file name for multi-pass stats.

nal-hrd (nal-hrd)

Set signal

HRD

information (requires vbv-bufsize to be set). Possible values:

none (none)

Disable

HRD

information signaling.

vbr (vbr)

Variable bit rate.

cbr (cbr)

Constant bit rate (not allowed in

MP4

container).

x264opts (N.A.)

Set any x264 option, see x264 --fullhelp for a list.

Argument is a list of key=value couples separated by ``:''. In filter and psy-rd options that use ``:'' as a separator themselves, use ``,'' instead. They accept it as well since long ago but this is kept undocumented for some reason.

For example to specify libx264 encoding options with ffmpeg:

        ffmpeg -i foo.mpg -vcodec libx264 -x264opts keyint=123:min-keyint=20 -an out.mkv

x264-params (N.A.)

Override the x264 configuration using a :-separated list of key=value parameters.

This option is functionally the same as the x264opts, but is duplicated for compatibility with the Libav fork.

For example to specify libx264 encoding options with ffmpeg:

        ffmpeg -i INPUT -c:v libx264 -x264-params level=30:bframes=0:weightp=0:\
        cabac=0:ref=1:vbv-maxrate=768:vbv-bufsize=2000:analyse=all:me=umh:\
        no-fast-pskip=1:subq=6:8x8dct=0:trellis=0 OUTPUT

Encoding ffpresets for common usages are provided so they can be used with the general presets system (e.g. passing the pre option).

libx265

x265 H.265/HEVC encoder wrapper.

This encoder requires the presence of the libx265 headers and library during configuration. You need to explicitly configure the build with --enable-libx265.

Options

preset

Set the x265 preset.

tune

Set the x265 tune parameter.

x265-params

Set x265 options using a list of key=value couples separated by ``:''. See x265 --help for a list of options.

For example to specify libx265 encoding options with -x265-params:

        ffmpeg -i input -c:v libx265 -x265-params crf=26:psy-rd=1 output.mp4

libxvid

Xvid Part 2 encoder wrapper.

This encoder requires the presence of the libxvidcore headers and library during configuration. You need to explicitly configure the build with "--enable-libxvid --enable-gpl".

The native "mpeg4" encoder supports the

Part 2 format, so users can encode to this format without this library.

Options

The following options are supported by the libxvid wrapper. Some of the following options are listed but are not documented, and correspond to shared codec options. See the Codec Options chapter for their documentation. The other shared options which are not listed have no effect for the libxvid encoder.

b

g

qmin

qmax

mpeg_quant

threads

bf

b_qfactor

b_qoffset

flags

Set specific encoding flags. Possible values:

mv4

Use four motion vector by macroblock.

aic

Enable high quality

AC

prediction.

gray

Only encode grayscale.

gmc

Enable the use of global motion compensation (

GMC

).

qpel

Enable quarter-pixel motion compensation.

cgop

Enable closed

GOP.

global_header

Place global headers in extradata instead of every keyframe.

trellis

me_method

Set motion estimation method. Possible values in decreasing order of speed and increasing order of quality:

zero

Use no motion estimation (default).

phods

x1

log

Enable advanced diamond zonal search for 16x16 blocks and half-pixel refinement for 16x16 blocks. x1 and log are aliases for phods.

epzs

Enable all of the things described above, plus advanced diamond zonal search for 8x8 blocks, half-pixel refinement for 8x8 blocks, and motion estimation on chroma planes.

full

Enable all of the things described above, plus extended 16x16 and 8x8 blocks search.

mbd

Set macroblock decision algorithm. Possible values in the increasing order of quality:

simple

Use macroblock comparing function algorithm (default).

bits

Enable rate distortion-based half pixel and quarter pixel refinement for 16x16 blocks.

rd

Enable all of the things described above, plus rate distortion-based half pixel and quarter pixel refinement for 8x8 blocks, and rate distortion-based search using square pattern.

lumi_aq

Enable lumi masking adaptive quantization when set to 1. Default is 0 (disabled).

variance_aq

Enable variance adaptive quantization when set to 1. Default is 0 (disabled).

When combined with lumi_aq, the resulting quality will not be better than any of the two specified individually. In other words, the resulting quality will be the worse one of the two effects.

ssim

Set structural similarity (

SSIM

) displaying method. Possible values:

off

Disable displaying of

SSIM

information.

avg

Output average

SSIM

at the end of encoding to stdout. The format of showing the average

SSIM

is:

        Average SSIM: %f

For users who are not familiar with C, %f means a float number, or a decimal (e.g. 0.939232).

frame

Output both per-frame

SSIM

data during encoding and average

SSIM

at the end of encoding to stdout. The format of per-frame information is:

               SSIM: avg: %1.3f min: %1.3f max: %1.3f

For users who are not familiar with C, %1.3f means a float number rounded to 3 digits after the dot (e.g. 0.932).

ssim_acc

Set

SSIM

accuracy. Valid options are integers within the range of 0-4, while 0 gives the most accurate result and 4 computes the fastest.

mpeg2

video encoder.

Options

seq_disp_ext integer

Specifies if the encoder should write a sequence_display_extension to the output.

-1

auto

Decide automatically to write it or not (this is the default) by checking if the data to be written is different from the default or unspecified values.

0

never

Never write it.

1

always

Always write it.

png

image encoder.

Private options

dpi integer

Set physical density of pixels, in dots per inch, unset by default

dpm integer

Set physical density of pixels, in dots per meter, unset by default

ProRes

Apple ProRes encoder.

FFmpeg contains 2 ProRes encoders, the prores-aw and prores-ks encoder. The used encoder can be chosen with the "-vcodec" option.

Private Options for prores-ks

profile integer

Select the ProRes profile to encode

proxy

lt

standard

hq

4444

quant_mat integer

Select quantization matrix.

auto

default

proxy

lt

standard

hq

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

bits_per_mb integer

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

mbs_per_slice integer

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

vendor string

Override the 4-byte vendor

ID. A

custom vendor

ID

like apl0 would claim the stream was produced by the Apple encoder.

alpha_bits integer

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

Speed considerations

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

Setting a higher bits_per_mb limit will improve the speed.

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

libkvazaar

Kvazaar H.265/HEVC encoder.

Requires the presence of the libkvazaar headers and library during configuration. You need to explicitly configure the build with --enable-libkvazaar.

Options

b

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

threads

Set number of encoding threads.

kvazaar-params

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

SUBTITLES ENCODERS

dvdsub

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

Options

even_rows_fix

When set to 1, enable a work-around that makes the number of pixel rows even in all subtitles. This fixes a problem with some players that cut off the bottom row if the number is odd. The work-around just adds a fully transparent row if needed. The overhead is low, typically one byte per subtitle on average.

By default, this work-around is disabled.

BITSTREAM FILTERS

When you configure your FFmpeg build, all the supported bitstream filters are enabled by default. You can list all available ones using the configure option "--list-bsfs".

You can disable all the bitstream filters using the configure option "--disable-bsfs", and selectively enable any bitstream filter using the option "--enable-bsf=BSF", or you can disable a particular bitstream filter using the option "--disable-bsf=BSF".

The option "-bsfs" of the ff* tools will display the list of all the supported bitstream filters included in your build.

The ff* tools have a -bsf option applied per stream, taking a comma-separated list of filters, whose parameters follow the filter name after a '='.

        ffmpeg -i INPUT -c:v copy -bsf:v filter1[=opt1=str1/opt2=str2][,filter2] OUTPUT

Below is a description of the currently available bitstream filters, with their parameters, if any.

aac_adtstoasc

Convert to Audio Specific Configuration bitstream filter.

This filter creates an

AudioSpecificConfig from an header and removes the header.

This is required for example when copying an

stream from a raw container to a or a file.

chomp

Remove zero padding at the end of a packet.

dump_extra

Add extradata to the beginning of the filtered packets.

The additional argument specifies which packets should be filtered. It accepts the values:

a

add extradata to all key packets, but only if local_header is set in the flags2 codec context field

k

add extradata to all key packets

e

add extradata to all packets

If not specified it is assumed k.

For example the following ffmpeg command forces a global header (thus disabling individual packet headers) in the H.264 packets generated by the "libx264" encoder, but corrects them by adding the header stored in extradata to the key packets:

        ffmpeg -i INPUT -map 0 -flags:v +global_header -c:v libx264 -bsf:v dump_extra out.ts

h264_mp4toannexb

Convert an H.264 bitstream from length prefixed mode to start code prefixed mode (as defined in the Annex B of the ITU-T H.264 specification).

This is required by some streaming formats, typically the

transport stream format (``mpegts'').

For example to remux an

file containing an H.264 stream to mpegts format with ffmpeg, you can use the command:

        ffmpeg -i INPUT.mp4 -codec copy -bsf:v h264_mp4toannexb OUTPUT.ts

imxdump

Modifies the bitstream to fit in and to be usable by the Final Cut Pro decoder. This filter only applies to the mpeg2video codec, and is likely not needed for Final Cut Pro 7 and newer with the appropriate -tag:v.

For example, to remux 30 MB/sec

to

        ffmpeg -i input.mxf -c copy -bsf:v imxdump -tag:v mx3n output.mov

mjpeg2jpeg

Convert packets to full packets.

is a video codec wherein each video frame is essentially a image. The individual frames can be extracted without loss, e.g. by

        ffmpeg -i ../some_mjpeg.avi -c:v copy frames_%d.jpg

Unfortunately, these chunks are incomplete

images, because they lack the segment required for decoding. Quoting from <www.digitalpreservation.gov/formats/fdd/fdd000063.shtml>:

Avery Lee, writing in the rec.video.desktop newsgroup in 2001, commented that ``

or at least the in AVIs having the fourcc, is restricted with a fixed --- and *omitted* --- Huffman table. The must be YCbCr colorspace, it must be 4:2:2, and it must use basic Huffman encoding, not arithmetic or progressive. . . . You can indeed extract the frames and decode them with a regular decoder, but you have to prepend the segment to them, or else the decoder won't have any idea how to decompress the data. The exact table necessary is given in the OpenDML spec.''

This bitstream filter patches the header of frames extracted from an

stream (carrying the header and lacking a segment) to produce fully qualified images.

        ffmpeg -i mjpeg-movie.avi -c:v copy -bsf:v mjpeg2jpeg frame_%d.jpg
        exiftran -i -9 frame*.jpg
        ffmpeg -i frame_%d.jpg -c:v copy rotated.avi

mjpega_dump_header

movsub

mp3_header_decompress

mpeg4_unpack_bframes

Unpack DivX-style packed B-frames.

DivX-style packed B-frames are not valid

and were only a workaround for the broken Video for Windows subsystem. They use more space, can cause minor sync issues, require more power to decode (unless the player has some decoded picture queue to compensate the 2,0,2,0 frame per packet style) and cause trouble if copied into a standard container like mp4 or mpeg-ps/ts, because decoders may not be able to decode them, since they are not valid

For example to fix an

file containing an stream with DivX-style packed B-frames using ffmpeg, you can use the command:

        ffmpeg -i INPUT.avi -codec copy -bsf:v mpeg4_unpack_bframes OUTPUT.avi

noise

Damages the contents of packets without damaging the container. Can be used for fuzzing or testing error resilience/concealment.

Parameters: A numeral string, whose value is related to how often output bytes will be modified. Therefore, values below or equal to 0 are forbidden, and the lower the more frequent bytes will be modified, with 1 meaning every byte is modified.

        ffmpeg -i INPUT -c copy -bsf noise[=1] output.mkv

applies the modification to every byte.

remove_extra

FORMAT OPTIONS

The libavformat library provides some generic global options, which can be set on all the muxers and demuxers. In addition each muxer or demuxer may support so-called private options, which are specific for that component.

Options may be set by specifying -option value in the FFmpeg tools, or by setting the value explicitly in the "AVFormatContext" options or using the libavutil/opt.h

for programmatic use.

The list of supported options follows:

avioflags flags (input/output)

Possible values:

direct

Reduce buffering.

probesize integer (input)

Set probing size in bytes, i.e. the size of the data to analyze to get stream information. A higher value will enable detecting more information in case it is dispersed into the stream, but will increase latency. Must be an integer not lesser than 32. It is 5000000 by default.

packetsize integer (output)

Set packet size.

fflags flags (input/output)

Set format flags.

Possible values:

ignidx

Ignore index.

fastseek

Enable fast, but inaccurate seeks for some formats.

genpts

Generate

PTS.

nofillin

Do not fill in missing values that can be exactly calculated.

noparse

Disable AVParsers, this needs "+nofillin" too.

igndts

Ignore

DTS.

discardcorrupt

Discard corrupted frames.

sortdts

Try to interleave output packets by

DTS.

keepside

Do not merge side data.

latm

Enable

RTP MP4A-LATM

payload.

nobuffer

Reduce the latency introduced by optional buffering

bitexact

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

seek2any integer (input)

Allow seeking to non-keyframes on demuxer level when supported if set to 1. Default is 0.

analyzeduration integer (input)

Specify how many microseconds are analyzed to probe the input. A higher value will enable detecting more accurate information, but will increase latency. It defaults to 5,000,000 microseconds = 5 seconds.

cryptokey hexadecimal string (input)

Set decryption key.

indexmem integer (input)

Set max memory used for timestamp index (per stream).

rtbufsize integer (input)

Set max memory used for buffering real-time frames.

fdebug flags (input/output)

Print specific debug info.

Possible values:

ts

max_delay integer (input/output)

Set maximum muxing or demuxing delay in microseconds.

fpsprobesize integer (input)

Set number of frames used to probe fps.

audio_preload integer (output)

Set microseconds by which audio packets should be interleaved earlier.

chunk_duration integer (output)

Set microseconds for each chunk.

chunk_size integer (output)

Set size in bytes for each chunk.

err_detect, f_err_detect flags (input)

Set error detection flags. "f_err_detect" is deprecated and should be used only via the ffmpeg tool.

Possible values:

crccheck

Verify embedded CRCs.

bitstream

Detect bitstream specification deviations.

buffer

Detect improper bitstream length.

explode

Abort decoding on minor error detection.

careful

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

compliant

Consider all spec non compliancies as errors.

aggressive

Consider things that a sane encoder should not do as an error.

max_interleave_delta integer (output)

Set maximum buffering duration for interleaving. The duration is expressed in microseconds, and defaults to 1000000 (1 second).

To ensure all the streams are interleaved correctly, libavformat will wait until it has at least one packet for each stream before actually writing any packets to the output file. When some streams are ``sparse'' (i.e. there are large gaps between successive packets), this can result in excessive buffering.

This field specifies the maximum difference between the timestamps of the first and the last packet in the muxing queue, above which libavformat will output a packet regardless of whether it has queued a packet for all the streams.

If set to 0, libavformat will continue buffering packets until it has a packet for each stream, regardless of the maximum timestamp difference between the buffered packets.

use_wallclock_as_timestamps integer (input)

Use wallclock as timestamps.

avoid_negative_ts integer (output)

Possible values:

make_non_negative

Shift timestamps to make them non-negative. Also note that this affects only leading negative timestamps, and not non-monotonic negative timestamps.

make_zero

Shift timestamps so that the first timestamp is 0.

auto (default)

Enables shifting when required by the target format.

disabled

Disables shifting of timestamp.

When shifting is enabled, all output timestamps are shifted by the same amount. Audio, video, and subtitles desynching and relative timestamp differences are preserved compared to how they would have been without shifting.

skip_initial_bytes integer (input)

Set number of bytes to skip before reading header and frames if set to 1. Default is 0.

correct_ts_overflow integer (input)

Correct single timestamp overflows if set to 1. Default is 1.

flush_packets integer (output)

Flush the underlying I/O stream after each packet. Default 1 enables it, and has the effect of reducing the latency; 0 disables it and may slightly increase performance in some cases.

output_ts_offset offset (output)

Set the output time offset.

offset must be a time duration specification, see the Time duration section in the ffmpeg-utils(1) manual.

The offset is added by the muxer to the output timestamps.

Specifying a positive offset means that the corresponding streams are delayed bt the time duration specified in offset. Default value is 0 (meaning that no offset is applied).

format_whitelist list (input)

``,'' separated List of allowed demuxers. By default all are allowed.

dump_separator string (input)

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

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

Format stream specifiers

Format stream specifiers allow selection of one or more streams that match specific properties.

Possible forms of stream specifiers are:

stream_index

Matches the stream with this index.

stream_type[:stream_index]

stream_type is one of following: 'v' for video, 'a' for audio, 's' for subtitle, 'd' for data, and 't' for attachments. If stream_index is given, then it matches the stream number stream_index of this type. Otherwise, it matches all streams of this type.

p:program_id[:stream_index]

If stream_index is given, then it matches the stream with number stream_index in the program with the id program_id. Otherwise, it matches all streams in the program.

#stream_id

Matches the stream by a format-specific

ID.

The exact semantics of stream specifiers is defined by the "avformat_match_stream_specifier()" function declared in the libavformat/avformat.h header.

DEMUXERS

Demuxers are configured elements in FFmpeg that can read the multimedia streams from a particular type of file.

When you configure your FFmpeg build, all the supported demuxers are enabled by default. You can list all available ones using the configure option "--list-demuxers".

You can disable all the demuxers using the configure option "--disable-demuxers", and selectively enable a single demuxer with the option "--enable-demuxer=DEMUXER", or disable it with the option "--disable-demuxer=DEMUXER".

The option "-formats" of the ff* tools will display the list of enabled demuxers.

The description of some of the currently available demuxers follows.

aa

Audible Format 2, 3, and 4 demuxer.

This demuxer is used to demux Audible Format 2, 3, and 4 (.aa) files.

applehttp

Apple Live Streaming demuxer.

This demuxer presents all AVStreams from all variant streams. The id field is set to the bitrate variant index number. By setting the discard flags on AVStreams (by pressing 'a' or 'v' in ffplay), the caller can decide which variant streams to actually receive. The total bitrate of the variant that the stream belongs to is available in a metadata key named ``variant_bitrate''.

apng

Animated Portable Network Graphics demuxer.

This demuxer is used to demux

files. All headers, but the signature, up to (but not including) the first fcTL chunk are transmitted as extradata. Frames are then split as being all the chunks between two fcTL ones, or between the last fcTL and chunks.

-ignore_loop bool

Ignore the loop variable in the file if set.

-max_fps int

Maximum framerate in frames per second (0 for no limit).

-default_fps int

Default framerate in frames per second when none is specified in the file (0 meaning as fast as possible).

asf

Advanced Systems Format demuxer.

This demuxer is used to demux

files and network streams.

-no_resync_search bool

Do not try to resynchronize by looking for a certain optional start code.

concat

Virtual concatenation script demuxer.

This demuxer reads a list of files and other directives from a text file and demuxes them one after the other, as if all their packet had been muxed together.

The timestamps in the files are adjusted so that the first file starts at 0 and each next file starts where the previous one finishes. Note that it is done globally and may cause gaps if all streams do not have exactly the same length.

All files must have the same streams (same codecs, same time base, etc.).

The duration of each file is used to adjust the timestamps of the next file: if the duration is incorrect (because it was computed using the bit-rate or because the file is truncated, for example), it can cause artifacts. The "duration" directive can be used to override the duration stored in each file.

Syntax

The script is a text file in extended-ASCII, with one directive per line. Empty lines, leading spaces and lines starting with '#' are ignored. The following directive is recognized:

file path

Path to a file to read; special characters and spaces must be escaped with backslash or single quotes.

All subsequent file-related directives apply to that file.

ffconcat version 1.0

Identify the script type and version. It also sets the safe option to 1 if it was to its default -1.

To make FFmpeg recognize the format automatically, this directive must appears exactly as is (no extra space or byte-order-mark) on the very first line of the script.

duration dur

Duration of the file. This information can be specified from the file; specifying it here may be more efficient or help if the information from the file is not available or accurate.

If the duration is set for all files, then it is possible to seek in the whole concatenated video.

inpoint timestamp

In point of the file. When the demuxer opens the file it instantly seeks to the specified timestamp. Seeking is done so that all streams can be presented successfully at In point.

This directive works best with intra frame codecs, because for non-intra frame ones you will usually get extra packets before the actual In point and the decoded content will most likely contain frames before In point too.

For each file, packets before the file In point will have timestamps less than the calculated start timestamp of the file (negative in case of the first file), and the duration of the files (if not specified by the "duration" directive) will be reduced based on their specified In point.

Because of potential packets before the specified In point, packet timestamps may overlap between two concatenated files.

outpoint timestamp

Out point of the file. When the demuxer reaches the specified decoding timestamp in any of the streams, it handles it as an end of file condition and skips the current and all the remaining packets from all streams.

Out point is exclusive, which means that the demuxer will not output packets with a decoding timestamp greater or equal to Out point.

This directive works best with intra frame codecs and formats where all streams are tightly interleaved. For non-intra frame codecs you will usually get additional packets with presentation timestamp after Out point therefore the decoded content will most likely contain frames after Out point too. If your streams are not tightly interleaved you may not get all the packets from all streams before Out point and you may only will be able to decode the earliest stream until Out point.

The duration of the files (if not specified by the "duration" directive) will be reduced based on their specified Out point.

file_packet_metadata key=value

Metadata of the packets of the file. The specified metadata will be set for each file packet. You can specify this directive multiple times to add multiple metadata entries.

stream

Introduce a stream in the virtual file. All subsequent stream-related directives apply to the last introduced stream. Some streams properties must be set in order to allow identifying the matching streams in the subfiles. If no streams are defined in the script, the streams from the first file are copied.

exact_stream_id id

Set the id of the stream. If this directive is given, the string with the corresponding id in the subfiles will be used. This is especially useful for MPEG-PS (

VOB

) files, where the order of the streams is not reliable.

Options

This demuxer accepts the following option:

safe

If set to 1, reject unsafe file paths. A file path is considered safe if it does not contain a protocol specification and is relative and all components only contain characters from the portable character set (letters, digits, period, underscore and hyphen) and have no period at the beginning of a component.

If set to 0, any file name is accepted.

The default is -1, it is equivalent to 1 if the format was automatically probed and 0 otherwise.

auto_convert

If set to 1, try to perform automatic conversions on packet data to make the streams concatenable. The default is 1.

Currently, the only conversion is adding the h264_mp4toannexb bitstream filter to H.264 streams in

MP4

format. This is necessary in particular if there are resolution changes.

flv

Adobe Flash Video Format demuxer.

This demuxer is used to demux

files and network streams.

-flv_metadata bool

Allocate the streams according to the onMetaData array content.

libgme

The Game Music Emu library is a collection of video game music file emulators.

See <code.google.com/p/game-music-emu> for more information.

Some files have multiple tracks. The demuxer will pick the first track by default. The track_index option can be used to select a different track. Track indexes start at 0. The demuxer exports the number of tracks as tracks meta data entry.

For very large files, the max_size option may have to be adjusted.

libquvi

Play media from Internet services using the quvi project.

The demuxer accepts a format option to request a specific quality. It is by default set to best.

See <quvi.sourceforge.net> for more information.

FFmpeg needs to be built with "--enable-libquvi" for this demuxer to be enabled.

gif

Animated demuxer.

It accepts the following options:

min_delay

Set the minimum valid delay between frames in hundredths of seconds. Range is 0 to 6000. Default value is 2.

max_gif_delay

Set the maximum valid delay between frames in hundredth of seconds. Range is 0 to 65535. Default value is 65535 (nearly eleven minutes), the maximum value allowed by the specification.

default_delay

Set the default delay between frames in hundredths of seconds. Range is 0 to 6000. Default value is 10.

ignore_loop

GIF

files can contain information to loop a certain number of times (or infinitely). If ignore_loop is set to 1, then the loop setting from the input will be ignored and looping will not occur. If set to 0, then looping will occur and will cycle the number of times according to the

GIF.

Default value is 1.

For example, with the overlay filter, place an infinitely looping

over another video:

        ffmpeg -i input.mp4 -ignore_loop 0 -i input.gif -filter_complex overlay=shortest=1 out.mkv

Note that in the above example the shortest option for overlay filter is used to end the output video at the length of the shortest input file, which in this case is input.mp4 as the

in this example loops infinitely.

image2

Image file demuxer.

This demuxer reads from a list of image files specified by a pattern. The syntax and meaning of the pattern is specified by the option pattern_type.

The pattern may contain a suffix which is used to automatically determine the format of the images contained in the files.

The size, the pixel format, and the format of each image must be the same for all the files in the sequence.

This demuxer accepts the following options:

framerate

Set the frame rate for the video stream. It defaults to 25.

loop

If set to 1, loop over the input. Default value is 0.

pattern_type

Select the pattern type used to interpret the provided filename.

pattern_type accepts one of the following values.

none

Disable pattern matching, therefore the video will only contain the specified image. You should use this option if you do not want to create sequences from multiple images and your filenames may contain special pattern characters.

sequence

Select a sequence pattern type, used to specify a sequence of files indexed by sequential numbers.

A sequence pattern may contain the string ``%d'' or "%0Nd``, which specifies the position of the characters representing a sequential number in each filename matched by the pattern. If the form ''%d0Nd" is used, the string representing the number in each filename is 0-padded and N is the total number of 0-padded digits representing the number. The literal character '%' can be specified in the pattern with the string ``%%''.

If the sequence pattern contains ``%d'' or "%0Nd", the first filename of the file list specified by the pattern must contain a number inclusively contained between start_number and start_number+start_number_range-1, and all the following numbers must be sequential.

For example the pattern ``img-%03d.bmp'' will match a sequence of filenames of the form img-001.bmp, img-002.bmp, ..., img-010.bmp, etc.; the pattern ``i%%m%%g-%d.jpg'' will match a sequence of filenames of the form i%m%g-1.jpg, i%m%g-2.jpg, ..., i%m%g-10.jpg, etc.

Note that the pattern must not necessarily contain ``%d'' or "%0Nd", for example to convert a single image file img.jpeg you can employ the command:

        ffmpeg -i img.jpeg img.png

glob

Select a glob wildcard pattern type.

The pattern is interpreted like a "glob()" pattern. This is only selectable if libavformat was compiled with globbing support.

glob_sequence (deprecated, will be removed)

Select a mixed glob wildcard/sequence pattern.

If your version of libavformat was compiled with globbing support, and the provided pattern contains at least one glob meta character among "%*?[]{}" that is preceded by an unescaped ``%'', the pattern is interpreted like a "glob()" pattern, otherwise it is interpreted like a sequence pattern.

All glob special characters "%*?[]{}" must be prefixed with ``%''. To escape a literal ``%'' you shall use ``%%''.

For example the pattern "foo-%*.jpeg" will match all the filenames prefixed by ``foo-'' and terminating with ``.jpeg'', and "foo-%?%?%?.jpeg" will match all the filenames prefixed with ``foo-'', followed by a sequence of three characters, and terminating with ``.jpeg''.

This pattern type is deprecated in favor of glob and sequence.

Default value is glob_sequence.

pixel_format

Set the pixel format of the images to read. If not specified the pixel format is guessed from the first image file in the sequence.

start_number

Set the index of the file matched by the image file pattern to start to read from. Default value is 0.

start_number_range

Set the index interval range to check when looking for the first image file in the sequence, starting from start_number. Default value is 5.

ts_from_file

If set to 1, will set frame timestamp to modification time of image file. Note that monotonity of timestamps is not provided: images go in the same order as without this option. Default value is 0. If set to 2, will set frame timestamp to the modification time of the image file in nanosecond precision.

video_size

Set the video size of the images to read. If not specified the video size is guessed from the first image file in the sequence.

Examples

*

Use ffmpeg for creating a video from the images in the file sequence img-001.jpeg, img-002.jpeg, ..., assuming an input frame rate of 10 frames per second:

        ffmpeg -framerate 10 -i 'img-%03d.jpeg' out.mkv

*

As above, but start by reading from a file with index 100 in the sequence:

        ffmpeg -framerate 10 -start_number 100 -i 'img-%03d.jpeg' out.mkv

*

Read images matching the ``*.png'' glob pattern , that is all the files terminating with the ``.png'' suffix:

        ffmpeg -framerate 10 -pattern_type glob -i "*.png" out.mkv

mov/mp4/3gp/Quicktme

Quicktime / demuxer.

This demuxer accepts the following options:

enable_drefs

Enable loading of external tracks, disabled by default. Enabling this can theoretically leak information in some use cases.

use_absolute_path

Allows loading of external tracks via absolute paths, disabled by default. Enabling this poses a security risk. It should only be enabled if the source is known to be non malicious.

mpegts

transport stream demuxer.

This demuxer accepts the following options:

resync_size

Set size limit for looking up a new synchronization. Default value is 65536.

fix_teletext_pts

Override teletext packet

PTS

and

DTS

values with the timestamps calculated from the

PCR

of the first program which the teletext stream is part of and is not discarded. Default value is 1, set this option to 0 if you want your teletext packet

PTS

and

DTS

values untouched.

ts_packetsize

Output option carrying the raw packet size in bytes. Show the detected raw packet size, cannot be set by the user.

scan_all_pmts

Scan and combine all PMTs. The value is an integer with value from -1 to 1 (-1 means automatic setting, 1 means enabled, 0 means disabled). Default value is -1.

rawvideo

Raw video demuxer.

This demuxer allows one to read raw video data. Since there is no header specifying the assumed video parameters, the user must specify them in order to be able to decode the data correctly.

This demuxer accepts the following options:

framerate

Set input video frame rate. Default value is 25.

pixel_format

Set the input video pixel format. Default value is "yuv420p".

video_size

Set the input video size. This value must be specified explicitly.

For example to read a rawvideo file input.raw with ffplay, assuming a pixel format of "rgb24", a video size of "320x240", and a frame rate of 10 images per second, use the command:

        ffplay -f rawvideo -pixel_format rgb24 -video_size 320x240 -framerate 10 input.raw

sbg

SBaGen script demuxer.

This demuxer reads the script language used by SBaGen <uazu.net/sbagen> to generate binaural beats sessions. A

script looks like that:

        -SE
        a: 300-2.5/3 440+4.5/0
        b: 300-2.5/0 440+4.5/3
        off: -
        NOW      == a
        +0:07:00 == b
        +0:14:00 == a
        +0:21:00 == b
        +0:30:00    off

A

script can mix absolute and relative timestamps. If the script uses either only absolute timestamps (including the script start time) or only relative ones, then its layout is fixed, and the conversion is straightforward. On the other hand, if the script mixes both kind of timestamps, then the reference for relative timestamps will be taken from the current time of day at the time the script is read, and the script layout will be frozen according to that reference. That means that if the script is directly played, the actual times will match the absolute timestamps up to the sound controller's clock accuracy, but if the user somehow pauses the playback or seeks, all times will be shifted accordingly.

tedcaptions

captions used for <www.ted.com>.

does not provide links to the captions, but they can be guessed from the page. The file tools/bookmarklets.html from the FFmpeg source tree contains a bookmarklet to expose them.

This demuxer accepts the following option:

start_time

Set the start time of the

TED

talk, in milliseconds. The default is 15000 (15s). It is used to sync the captions with the downloadable videos, because they include a 15s intro.

Example: convert the captions to a format most players understand:

        ffmpeg -i www.ted.com/talks/subtitles/id/1/lang/en talk1-en.srt

MUXERS

Muxers are configured elements in FFmpeg which allow writing multimedia streams to a particular type of file.

When you configure your FFmpeg build, all the supported muxers are enabled by default. You can list all available muxers using the configure option "--list-muxers".

You can disable all the muxers with the configure option "--disable-muxers" and selectively enable / disable single muxers with the options "--enable-muxer=MUXER" / "--disable-muxer=MUXER".

The option "-formats" of the ff* tools will display the list of enabled muxers.

A description of some of the currently available muxers follows.

aiff

Audio Interchange File Format muxer.

Options

It accepts the following options:

write_id3v2

Enable ID3v2 tags writing when set to 1. Default is 0 (disabled).

id3v2_version

Select ID3v2 version to write. Currently only version 3 and 4 (aka. ID3v2.3 and ID3v2.4) are supported. The default is version 4.

crc

(Cyclic Redundancy Check) testing format.

This muxer computes and prints the Adler-32

of all the input audio and video frames. By default audio frames are converted to signed 16-bit raw audio and video frames to raw video before computing the

The output of the muxer consists of a single line of the form: CRC=0x

, where is a hexadecimal number 0-padded to 8 digits containing the for all the decoded input frames.

See also the framecrc muxer.

Examples

For example to compute the

of the input, and store it in the file out.crc:

        ffmpeg -i INPUT -f crc out.crc

You can print the

to stdout with the command:

        ffmpeg -i INPUT -f crc -

You can select the output format of each frame with ffmpeg by specifying the audio and video codec and format. For example to compute the

of the input audio converted to unsigned 8-bit and the input video converted to video, use the command:

        ffmpeg -i INPUT -c:a pcm_u8 -c:v mpeg2video -f crc -

framecrc

Per-packet (Cyclic Redundancy Check) testing format.

This muxer computes and prints the Adler-32

for each audio and video packet. By default audio frames are converted to signed 16-bit raw audio and video frames to raw video before computing the

The output of the muxer consists of a line for each audio and video packet of the form:

        <stream_index>, <packet_dts>, <packet_pts>, <packet_duration>, <packet_size>, 0x<CRC>

is a hexadecimal number 0-padded to 8 digits containing the of the packet.

Examples

For example to compute the

of the audio and video frames in , converted to raw audio and video packets, and store it in the file out.crc:

        ffmpeg -i INPUT -f framecrc out.crc

To print the information to stdout, use the command:

        ffmpeg -i INPUT -f framecrc -

With ffmpeg, you can select the output format to which the audio and video frames are encoded before computing the

for each packet by specifying the audio and video codec. For example, to compute the of each decoded input audio frame converted to unsigned 8-bit and of each decoded input video frame converted to video, use the command:

        ffmpeg -i INPUT -c:a pcm_u8 -c:v mpeg2video -f framecrc -

See also the crc muxer.

framemd5

Per-packet testing format.

This muxer computes and prints the

hash for each audio and video packet. By default audio frames are converted to signed 16-bit raw audio and video frames to raw video before computing the hash.

The output of the muxer consists of a line for each audio and video packet of the form:

        <stream_index>, <packet_dts>, <packet_pts>, <packet_duration>, <packet_size>, <MD5>

is a hexadecimal number representing the computed hash for the packet.

Examples

For example to compute the

of the audio and video frames in , converted to raw audio and video packets, and store it in the file out.md5:

        ffmpeg -i INPUT -f framemd5 out.md5

To print the information to stdout, use the command:

        ffmpeg -i INPUT -f framemd5 -

See also the md5 muxer.

gif

Animated muxer.

It accepts the following options:

loop

Set the number of times to loop the output. Use "-1" for no loop, 0 for looping indefinitely (default).

final_delay

Force the delay (expressed in centiseconds) after the last frame. Each frame ends with a delay until the next frame. The default is "-1", which is a special value to tell the muxer to re-use the previous delay. In case of a loop, you might want to customize this value to mark a pause for instance.

For example, to encode a gif looping 10 times, with a 5 seconds delay between the loops:

        ffmpeg -i INPUT -loop 10 -final_delay 500 out.gif

Note 1: if you wish to extract the frames in separate

files, you need to force the image2 muxer:

        ffmpeg -i INPUT -c:v gif -f image2 "out%d.gif"

Note 2: the

format has a very small time base: the delay between two frames can not be smaller than one centi second.

hls

Apple Live Streaming muxer that segments MPEG-TS according to the Live Streaming () specification.

It creates a playlist file, and one or more segment files. The output filename specifies the playlist filename.

By default, the muxer creates a file for each segment produced. These files have the same name as the playlist, followed by a sequential number and a .ts extension.

For example, to convert an input file with ffmpeg:

        ffmpeg -i in.nut out.m3u8

This example will produce the playlist, out.m3u8, and segment files: out0.ts, out1.ts, out2.ts, etc.

See also the segment muxer, which provides a more generic and flexible implementation of a segmenter, and can be used to perform

segmentation.

Options

This muxer supports the following options:

hls_time seconds

Set the segment length in seconds. Default value is 2.

hls_list_size size

Set the maximum number of playlist entries. If set to 0 the list file will contain all the segments. Default value is 5.

hls_ts_options options_list

Set output format options using a :-separated list of key=value parameters. Values containing ":" special characters must be escaped.

hls_wrap wrap

Set the number after which the segment filename number (the number specified in each segment file) wraps. If set to 0 the number will be never wrapped. Default value is 0.

This option is useful to avoid to fill the disk with many segment files, and limits the maximum number of segment files written to disk to wrap.

start_number number

Start the playlist sequence number from number. Default value is 0.

hls_allow_cache allowcache

Explicitly set whether the client

MAY \fIs0(1) or

MUST NOT \fIs0(0) cache media segments.

hls_base_url baseurl

Append baseurl to every entry in the playlist. Useful to generate playlists with absolute paths.

Note that the playlist sequence number must be unique for each segment and it is not to be confused with the segment filename sequence number which can be cyclic, for example if the wrap option is specified.

hls_segment_filename filename

Set the segment filename. Unless hls_flags single_file is set filename is used as a string format with the segment number: