5871ee5072
This option can be generally useful to set an output offset, needed when setting an absolute index in the output.
205 lines
6.3 KiB
Plaintext
205 lines
6.3 KiB
Plaintext
@chapter Format Options
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@c man begin FORMAT OPTIONS
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The libavformat library provides some generic global options, which
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can be set on all the muxers and demuxers. In addition each muxer or
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demuxer may support so-called private options, which are specific for
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that component.
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Options may be set by specifying -@var{option} @var{value} in the
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FFmpeg tools, or by setting the value explicitly in the
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@code{AVFormatContext} options or using the @file{libavutil/opt.h} API
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for programmatic use.
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The list of supported options follows:
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@table @option
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@item avioflags @var{flags} (@emph{input/output})
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Possible values:
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@table @samp
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@item direct
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Reduce buffering.
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@end table
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@item probesize @var{integer} (@emph{input})
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Set probing size in bytes, i.e. the size of the data to analyze to get
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stream information. A higher value will allow to detect more
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information in case it is dispersed into the stream, but will increase
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latency. Must be an integer not lesser than 32. It is 5000000 by default.
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@item packetsize @var{integer} (@emph{output})
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Set packet size.
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@item fflags @var{flags} (@emph{input/output})
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Set format flags.
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Possible values:
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@table @samp
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@item ignidx
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Ignore index.
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@item genpts
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Generate PTS.
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@item nofillin
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Do not fill in missing values that can be exactly calculated.
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@item noparse
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Disable AVParsers, this needs @code{+nofillin} too.
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@item igndts
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Ignore DTS.
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@item discardcorrupt
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Discard corrupted frames.
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@item sortdts
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Try to interleave output packets by DTS.
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@item keepside
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Do not merge side data.
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@item latm
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Enable RTP MP4A-LATM payload.
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@item nobuffer
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Reduce the latency introduced by optional buffering
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@end table
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@item seek2any @var{integer} (@emph{input})
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Allow seeking to non-keyframes on demuxer level when supported if set to 1.
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Default is 0.
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@item analyzeduration @var{integer} (@emph{input})
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Specify how many microseconds are analyzed to probe the input. A
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higher value will allow to detect more accurate information, but will
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increase latency. It defaults to 5,000,000 microseconds = 5 seconds.
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@item cryptokey @var{hexadecimal string} (@emph{input})
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Set decryption key.
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@item indexmem @var{integer} (@emph{input})
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Set max memory used for timestamp index (per stream).
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@item rtbufsize @var{integer} (@emph{input})
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Set max memory used for buffering real-time frames.
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@item fdebug @var{flags} (@emph{input/output})
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Print specific debug info.
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Possible values:
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@table @samp
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@item ts
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@end table
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@item max_delay @var{integer} (@emph{input/output})
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Set maximum muxing or demuxing delay in microseconds.
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@item fpsprobesize @var{integer} (@emph{input})
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Set number of frames used to probe fps.
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@item audio_preload @var{integer} (@emph{output})
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Set microseconds by which audio packets should be interleaved earlier.
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@item chunk_duration @var{integer} (@emph{output})
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Set microseconds for each chunk.
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@item chunk_size @var{integer} (@emph{output})
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Set size in bytes for each chunk.
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@item err_detect, f_err_detect @var{flags} (@emph{input})
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Set error detection flags. @code{f_err_detect} is deprecated and
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should be used only via the @command{ffmpeg} tool.
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Possible values:
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@table @samp
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@item crccheck
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Verify embedded CRCs.
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@item bitstream
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Detect bitstream specification deviations.
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@item buffer
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Detect improper bitstream length.
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@item explode
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Abort decoding on minor error detection.
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@item careful
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Consider things that violate the spec and have not been seen in the
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wild as errors.
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@item compliant
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Consider all spec non compliancies as errors.
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@item aggressive
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Consider things that a sane encoder should not do as an error.
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@end table
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@item use_wallclock_as_timestamps @var{integer} (@emph{input})
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Use wallclock as timestamps.
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@item avoid_negative_ts @var{integer} (@emph{output})
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Shift timestamps to make them non-negative. A value of 1 enables shifting,
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a value of 0 disables it, the default value of -1 enables shifting
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when required by the target format.
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When shifting is enabled, all output timestamps are shifted by the
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same amount. Audio, video, and subtitles desynching and relative
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timestamp differences are preserved compared to how they would have
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been without shifting.
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Also note that this affects only leading negative timestamps, and not
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non-monotonic negative timestamps.
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@item skip_initial_bytes @var{integer} (@emph{input})
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Set number of bytes to skip before reading header and frames if set to 1.
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Default is 0.
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@item correct_ts_overflow @var{integer} (@emph{input})
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Correct single timestamp overflows if set to 1. Default is 1.
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@item flush_packets @var{integer} (@emph{output})
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Flush the underlying I/O stream after each packet. Default 1 enables it, and
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has the effect of reducing the latency; 0 disables it and may slightly
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increase performance in some cases.
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@item output_ts_offset @var{offset} (@emph{output})
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Set the output time offset.
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@var{offset} must be a time duration specification,
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see @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}.
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The offset is added by the muxer to the output timestamps.
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Specifying a positive offset means that the corresponding streams are
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delayed bt the time duration specified in @var{offset}. Default value
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is @code{0} (meaning that no offset is applied).
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@end table
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@c man end FORMAT OPTIONS
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@anchor{Format stream specifiers}
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@section Format stream specifiers
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Format stream specifiers allow selection of one or more streams that
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match specific properties.
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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.
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@item @var{stream_type}[:@var{stream_index}]
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@var{stream_type} is one of following: 'v' for video, 'a' for audio,
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's' for subtitle, 'd' for data, and 't' for attachments. If
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@var{stream_index} is given, then it matches the stream number
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@var{stream_index} of this type. Otherwise, it matches all streams of
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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 it matches the stream with number
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@var{stream_index} in the program with the id
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@var{program_id}. Otherwise, it matches all streams in the program.
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@item #@var{stream_id}
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Matches the stream by a format-specific ID.
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@end table
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The exact semantics of stream specifiers is defined by the
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@code{avformat_match_stream_specifier()} function declared in the
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@file{libavformat/avformat.h} header.
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@ifclear config-writeonly
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@include demuxers.texi
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@end ifclear
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@ifclear config-readonly
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@include muxers.texi
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@end ifclear
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@include metadata.texi
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