189 lines
5.8 KiB
Plaintext
189 lines
5.8 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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@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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@include demuxers.texi
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@include muxers.texi
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@include metadata.texi
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