avformat/aviobuf: fix checks in ffio_ensure_seekback

[ffmpeg] / doc / fftools-common-opts.texi

All the numerical options, if not specified otherwise, accept a string
representing a number as input, which may be followed by one of the SI
unit prefixes, for example: 'K', 'M', or 'G'.

If 'i' is appended to the SI unit prefix, the complete prefix will be
interpreted as a unit prefix for binary multiples, which are based on
powers of 1024 instead of powers of 1000. Appending 'B' to the SI unit
prefix multiplies the value by 8. This allows using, for example:
'KB', 'MiB', 'G' and 'B' as number suffixes.

Options which do not take arguments are boolean options, and set the
corresponding value to true. They can be set to false by prefixing
the option name with "no". For example using "-nofoo"
will set the boolean option with name "foo" to false.

@anchor{Stream specifiers}
@section 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. @code{-codec:a:1 ac3} contains the
@code{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 @code{-b:a 128k} matches all audio
streams.

An empty stream specifier matches all streams. For example, @code{-codec copy}
or @code{-codec: copy} would copy all the streams without reencoding.

Possible forms of stream specifiers are:
@table @option
@item @var{stream_index}
Matches the stream with this index. E.g. @code{-threads:1 4} would set the
thread count for the second stream to 4. If @var{stream_index} is used as an
additional stream specifier (see below), then it selects stream number
@var{stream_index} from the matching streams. Stream numbering is based on the
order of the streams as detected by libavformat except when a program ID is
also specified. In this case it is based on the ordering of the streams in the
program.
@item @var{stream_type}[:@var{additional_stream_specifier}]
@var{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 @var{additional_stream_specifier} is used, then
it matches streams which both have this type and match the
@var{additional_stream_specifier}. Otherwise, it matches all streams of the
specified type.
@item p:@var{program_id}[:@var{additional_stream_specifier}]
Matches streams which are in the program with the id @var{program_id}. If
@var{additional_stream_specifier} is used, then it matches streams which both
are part of the program and match the @var{additional_stream_specifier}.

@item #@var{stream_id} or i:@var{stream_id}
Match the stream by stream id (e.g. PID in MPEG-TS container).
@item m:@var{key}[:@var{value}]
Matches streams with the metadata tag @var{key} having the specified value. If
@var{value} is not given, matches streams that contain the given tag with any
value.
@item 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 @command{ffmpeg}, matching by metadata will only work properly for
input files.
@end table

@section Generic options

These options are shared amongst the ff* tools.

@table @option

@item -L
Show license.

@item -h, -?, -help, --help [@var{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 @var{arg} are:
@table @option
@item long
Print advanced tool options in addition to the basic tool options.

@item full
Print complete list of options, including shared and private options
for encoders, decoders, demuxers, muxers, filters, etc.

@item decoder=@var{decoder_name}
Print detailed information about the decoder named @var{decoder_name}. Use the
@option{-decoders} option to get a list of all decoders.

@item encoder=@var{encoder_name}
Print detailed information about the encoder named @var{encoder_name}. Use the
@option{-encoders} option to get a list of all encoders.

@item demuxer=@var{demuxer_name}
Print detailed information about the demuxer named @var{demuxer_name}. Use the
@option{-formats} option to get a list of all demuxers and muxers.

@item muxer=@var{muxer_name}
Print detailed information about the muxer named @var{muxer_name}. Use the
@option{-formats} option to get a list of all muxers and demuxers.

@item filter=@var{filter_name}
Print detailed information about the filter named @var{filter_name}. Use the
@option{-filters} option to get a list of all filters.

@item bsf=@var{bitstream_filter_name}
Print detailed information about the bitstream filter named @var{bitstream_filter_name}.
Use the @option{-bsfs} option to get a list of all bitstream filters.

@item protocol=@var{protocol_name}
Print detailed information about the protocol named @var{protocol_name}.
Use the @option{-protocols} option to get a list of all protocols.
@end table

@item -version
Show version.

@item -formats
Show available formats (including devices).

@item -demuxers
Show available demuxers.

@item -muxers
Show available muxers.

@item -devices
Show available devices.

@item -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.

@item -decoders
Show available decoders.

@item -encoders
Show all available encoders.

@item -bsfs
Show available bitstream filters.

@item -protocols
Show available protocols.

@item -filters
Show available libavfilter filters.

@item -pix_fmts
Show available pixel formats.

@item -sample_fmts
Show available sample formats.

@item -layouts
Show channel names and standard channel layouts.

@item -colors
Show recognized color names.

@item -sources @var{device}[,@var{opt1}=@var{val1}[,@var{opt2}=@var{val2}]...]
Show autodetected sources of the input device.
Some devices may provide system-dependent source names that cannot be autodetected.
The returned list cannot be assumed to be always complete.
@example
ffmpeg -sources pulse,server=192.168.0.4
@end example

@item -sinks @var{device}[,@var{opt1}=@var{val1}[,@var{opt2}=@var{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.
@example
ffmpeg -sinks pulse,server=192.168.0.4
@end example

@item -loglevel [@var{flags}+]@var{loglevel} | -v [@var{flags}+]@var{loglevel}
Set logging level and flags used by the library.

The optional @var{flags} prefix can consist of the following values:
@table @samp
@item 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.
@item level
Indicates that log output should add a @code{[level]} prefix to each message
line. This can be used as an alternative to log coloring, e.g. when dumping the
log to file.
@end table
Flags can also be used alone by adding a '+'/'-' prefix to set/reset a single
flag without affecting other @var{flags} or changing @var{loglevel}. When
setting both @var{flags} and @var{loglevel}, a '+' separator is expected
between the last @var{flags} value and before @var{loglevel}.

@var{loglevel} is a string or a number containing one of the following values:
@table @samp
@item quiet, -8
Show nothing at all; be silent.
@item panic, 0
Only show fatal errors which could lead the process to crash, such as
an assertion failure. This is not currently used for anything.
@item fatal, 8
Only show fatal errors. These are errors after which the process absolutely
cannot continue.
@item error, 16
Show all errors, including ones which can be recovered from.
@item warning, 24
Show all warnings and errors. Any message related to possibly
incorrect or unexpected events will be shown.
@item info, 32
Show informative messages during processing. This is in addition to
warnings and errors. This is the default value.
@item verbose, 40
Same as @code{info}, except more verbose.
@item debug, 48
Show everything, including debugging information.
@item trace, 56
@end table

For example to enable repeated log output, add the @code{level} prefix, and set
@var{loglevel} to @code{verbose}:
@example
ffmpeg -loglevel repeat+level+verbose -i input output
@end example
Another example that enables repeated log output without affecting current
state of @code{level} prefix flag or @var{loglevel}:
@example
ffmpeg [...] -loglevel +repeat
@end example

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
@env{AV_LOG_FORCE_NOCOLOR}, or can be forced setting
the environment variable @env{AV_LOG_FORCE_COLOR}.

@item -report
Dump full command line and log output to a file named
@code{@var{program}-@var{YYYYMMDD}-@var{HHMMSS}.log} in the current
directory.
This file can be useful for bug reports.
It also implies @code{-loglevel debug}.

Setting the environment variable @env{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:
@table @option
@item file
set the file name to use for the report; @code{%p} is expanded to the name
of the program, @code{%t} is expanded to a timestamp, @code{%%} is expanded
to a plain @code{%}
@item level
set the log verbosity level using a numerical value (see @code{-loglevel}).
@end table

For example, to output a report to a file named @file{ffreport.log}
using a log level of @code{32} (alias for log level @code{info}):

@example
FFREPORT=file=ffreport.log:level=32 ffmpeg -i input output
@end example

Errors in parsing the environment variable are not fatal, and will not
appear in the report.

@item -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.

@item -cpuflags flags (@emph{global})
Allows setting and clearing cpu flags. This option is intended
for testing. Do not use it unless you know what you're doing.
@example
ffmpeg -cpuflags -sse+mmx ...
ffmpeg -cpuflags mmx ...
ffmpeg -cpuflags 0 ...
@end example
Possible flags for this option are:
@table @samp
@item x86
@table @samp
@item mmx
@item mmxext
@item sse
@item sse2
@item sse2slow
@item sse3
@item sse3slow
@item ssse3
@item atom
@item sse4.1
@item sse4.2
@item avx
@item avx2
@item xop
@item fma3
@item fma4
@item 3dnow
@item 3dnowext
@item bmi1
@item bmi2
@item cmov
@end table
@item ARM
@table @samp
@item armv5te
@item armv6
@item armv6t2
@item vfp
@item vfpv3
@item neon
@item setend
@end table
@item AArch64
@table @samp
@item armv8
@item vfp
@item neon
@end table
@item PowerPC
@table @samp
@item altivec
@end table
@item Specific Processors
@table @samp
@item pentium2
@item pentium3
@item pentium4
@item k6
@item k62
@item athlon
@item athlonxp
@item k8
@end table
@end table
@end table

@section AVOptions

These options are provided directly by the libavformat, libavdevice and
libavcodec libraries. To see the list of available AVOptions, use the
@option{-help} option. They are separated into two categories:
@table @option
@item 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.
@item private
These options are specific to the given container, device or codec. Private
options are listed under their corresponding containers/devices/codecs.
@end table

For example to write an ID3v2.3 header instead of a default ID3v2.4 to
an MP3 file, use the @option{id3v2_version} private option of the MP3
muxer:
@example
ffmpeg -i input.flac -id3v2_version 3 out.mp3
@end example

All codec AVOptions are per-stream, and thus a stream specifier
should be attached to them:
@example
ffmpeg -i multichannel.mxf -map 0:v:0 -map 0:a:0 -map 0:a:0 -c:a:0 ac3 -b:a:0 640k -ac:a:1 2 -c:a:1 aac -b:2 128k out.mp4
@end example

In the above example, a multichannel audio stream is mapped twice for output.
The first instance is encoded with codec ac3 and bitrate 640k.
The second instance is downmixed to 2 channels and encoded with codec aac. A bitrate of 128k is specified for it using
absolute index of the output stream.

Note: the @option{-nooption} syntax cannot be used for boolean
AVOptions, use @option{-option 0}/@option{-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.