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159 lines
5.0 KiB
Plaintext
159 lines
5.0 KiB
Plaintext
All the numerical options, if not specified otherwise, accept in input
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a string representing a number, which may contain one of the
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International System number postfixes, for example 'K', 'M', 'G'.
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If 'i' is appended after the postfix, powers of 2 are used instead of
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powers of 10. The 'B' postfix multiplies the value for 8, and can be
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appended after another postfix or used alone. This allows using for
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example 'KB', 'MiB', 'G' and 'B' as postfix.
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Options which do not take arguments are boolean options, and set the
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corresponding value to true. They can be set to false by prefixing
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with "no" the option name, for example using "-nofoo" in the
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command line will set to false the boolean option with name "foo".
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@anchor{Stream specifiers}
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@section Stream specifiers
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Some options are applied per-stream, e.g. bitrate or codec. Stream specifiers
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are used to precisely specify which stream(s) does a given option belong to.
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A stream specifier is a string generally appended to the option name and
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separated from it by a colon. E.g. @code{-codec:a:1 ac3} option contains
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@code{a:1} stream specifer, which matches the second audio stream. Therefore it
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would select the ac3 codec for the second audio stream.
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A stream specifier can match several stream, the option is then applied to all
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of them. E.g. the stream specifier in @code{-b:a 128k} matches all audio
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streams.
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An empty stream specifier matches all streams, for example @code{-codec copy}
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or @code{-codec: copy} would copy all the streams without reencoding.
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Possible forms of stream specifiers are:
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@table @option
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@item @var{stream_index}
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Matches the stream with this index. E.g. @code{-threads:1 4} would set the
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thread count for the second stream to 4.
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@item @var{stream_type}[:@var{stream_index}]
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@var{stream_type} is one of: 'v' for video, 'a' for audio, 's' for subtitle,
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'd' for data and 't' for attachments. If @var{stream_index} is given, then
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matches stream number @var{stream_index} of this type. Otherwise matches all
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streams of this type.
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@item p:@var{program_id}[:@var{stream_index}]
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If @var{stream_index} is given, then matches stream number @var{stream_index} in
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program with id @var{program_id}. Otherwise matches all streams in this program.
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@end table
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@section Generic options
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These options are shared amongst the av* tools.
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@table @option
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@item -L
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Show license.
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@item -h, -?, -help, --help
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Show help.
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@item -version
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Show version.
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@item -formats
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Show available formats.
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The fields preceding the format names have the following meanings:
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@table @samp
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@item D
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Decoding available
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@item E
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Encoding available
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@end table
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@item -codecs
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Show available codecs.
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The fields preceding the codec names have the following meanings:
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@table @samp
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@item D
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Decoding available
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@item E
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Encoding available
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@item V/A/S
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Video/audio/subtitle codec
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@item S
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Codec supports slices
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@item D
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Codec supports direct rendering
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@item T
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Codec can handle input truncated at random locations instead of only at frame boundaries
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@end table
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@item -bsfs
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Show available bitstream filters.
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@item -protocols
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Show available protocols.
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@item -filters
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Show available libavfilter filters.
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@item -pix_fmts
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Show available pixel formats.
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@item -sample_fmts
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Show available sample formats.
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@item -loglevel @var{loglevel} | -v @var{loglevel}
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Set the logging level used by the library.
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@var{loglevel} is a number or a string containing one of the following values:
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@table @samp
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@item quiet
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@item panic
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@item fatal
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@item error
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@item warning
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@item info
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@item verbose
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@item debug
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@end table
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By default the program logs to stderr, if coloring is supported by the
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terminal, colors are used to mark errors and warnings. Log coloring
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can be disabled setting the environment variable
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@env{FFMPEG_FORCE_NOCOLOR} or @env{NO_COLOR}, or can be forced setting
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the environment variable @env{FFMPEG_FORCE_COLOR}.
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The use of the environment variable @env{NO_COLOR} is deprecated and
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will be dropped in a following Libav version.
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@end table
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@section AVOptions
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These options are provided directly by the libavformat, libavdevice and
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libavcodec libraries. To see the list of available AVOptions, use the
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@option{-help} option. They are separated into two categories:
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@table @option
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@item generic
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These options can be set for any container, codec or device. Generic options
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are listed under AVFormatContext options for containers/devices and under
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AVCodecContext options for codecs.
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@item private
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These options are specific to the given container, device or codec. Private
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options are listed under their corresponding containers/devices/codecs.
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@end table
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For example to write an ID3v2.3 header instead of a default ID3v2.4 to
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an MP3 file, use the @option{id3v2_version} private option of the MP3
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muxer:
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@example
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avconv -i input.flac -id3v2_version 3 out.mp3
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@end example
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All codec AVOptions are obviously per-stream, so the chapter on stream
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specifiers applies to them
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Note @option{-nooption} syntax cannot be used for boolean AVOptions,
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use @option{-option 0}/@option{-option 1}.
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Note2 old undocumented way of specifying per-stream AVOptions by prepending
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v/a/s to the options name is now obsolete and will be removed soon.
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