1@chapter Format Options 2@c man begin FORMAT OPTIONS 3 4The libavformat library provides some generic global options, which 5can be set on all the muxers and demuxers. In addition each muxer or 6demuxer may support so-called private options, which are specific for 7that component. 8 9Options may be set by specifying -@var{option} @var{value} in the 10FFmpeg tools, or by setting the value explicitly in the 11@code{AVFormatContext} options or using the @file{libavutil/opt.h} API 12for programmatic use. 13 14The list of supported options follows: 15 16@table @option 17@item avioflags @var{flags} (@emph{input/output}) 18Possible values: 19@table @samp 20@item direct 21Reduce buffering. 22@end table 23 24@item probesize @var{integer} (@emph{input}) 25Set probing size in bytes, i.e. the size of the data to analyze to get 26stream information. A higher value will enable detecting more 27information in case it is dispersed into the stream, but will increase 28latency. Must be an integer not lesser than 32. It is 5000000 by default. 29 30@item max_probe_packets @var{integer} (@emph{input}) 31Set the maximum number of buffered packets when probing a codec. 32Default is 2500 packets. 33 34@item packetsize @var{integer} (@emph{output}) 35Set packet size. 36 37@item fflags @var{flags} 38Set format flags. Some are implemented for a limited number of formats. 39 40Possible values for input files: 41@table @samp 42@item discardcorrupt 43Discard corrupted packets. 44@item fastseek 45Enable fast, but inaccurate seeks for some formats. 46@item genpts 47Generate missing PTS if DTS is present. 48@item igndts 49Ignore DTS if PTS is set. Inert when nofillin is set. 50@item ignidx 51Ignore index. 52@item nobuffer 53Reduce the latency introduced by buffering during initial input streams analysis. 54@item nofillin 55Do not fill in missing values in packet fields that can be exactly calculated. 56@item noparse 57Disable AVParsers, this needs @code{+nofillin} too. 58@item sortdts 59Try to interleave output packets by DTS. At present, available only for AVIs with an index. 60@end table 61 62Possible values for output files: 63@table @samp 64@item autobsf 65Automatically apply bitstream filters as required by the output format. Enabled by default. 66@item bitexact 67Only write platform-, build- and time-independent data. 68This ensures that file and data checksums are reproducible and match between 69platforms. Its primary use is for regression testing. 70@item flush_packets 71Write out packets immediately. 72@item shortest 73Stop muxing at the end of the shortest stream. 74It may be needed to increase max_interleave_delta to avoid flushing the longer 75streams before EOF. 76@end table 77 78@item seek2any @var{integer} (@emph{input}) 79Allow seeking to non-keyframes on demuxer level when supported if set to 1. 80Default is 0. 81 82@item analyzeduration @var{integer} (@emph{input}) 83Specify how many microseconds are analyzed to probe the input. A 84higher value will enable detecting more accurate information, but will 85increase latency. It defaults to 5,000,000 microseconds = 5 seconds. 86 87@item cryptokey @var{hexadecimal string} (@emph{input}) 88Set decryption key. 89 90@item indexmem @var{integer} (@emph{input}) 91Set max memory used for timestamp index (per stream). 92 93@item rtbufsize @var{integer} (@emph{input}) 94Set max memory used for buffering real-time frames. 95 96@item fdebug @var{flags} (@emph{input/output}) 97Print specific debug info. 98 99Possible values: 100@table @samp 101@item ts 102@end table 103 104@item max_delay @var{integer} (@emph{input/output}) 105Set maximum muxing or demuxing delay in microseconds. 106 107@item fpsprobesize @var{integer} (@emph{input}) 108Set number of frames used to probe fps. 109 110@item audio_preload @var{integer} (@emph{output}) 111Set microseconds by which audio packets should be interleaved earlier. 112 113@item chunk_duration @var{integer} (@emph{output}) 114Set microseconds for each chunk. 115 116@item chunk_size @var{integer} (@emph{output}) 117Set size in bytes for each chunk. 118 119@item err_detect, f_err_detect @var{flags} (@emph{input}) 120Set error detection flags. @code{f_err_detect} is deprecated and 121should be used only via the @command{ffmpeg} tool. 122 123Possible values: 124@table @samp 125@item crccheck 126Verify embedded CRCs. 127@item bitstream 128Detect bitstream specification deviations. 129@item buffer 130Detect improper bitstream length. 131@item explode 132Abort decoding on minor error detection. 133@item careful 134Consider things that violate the spec and have not been seen in the 135wild as errors. 136@item compliant 137Consider all spec non compliancies as errors. 138@item aggressive 139Consider things that a sane encoder should not do as an error. 140@end table 141 142@item max_interleave_delta @var{integer} (@emph{output}) 143Set maximum buffering duration for interleaving. The duration is 144expressed in microseconds, and defaults to 10000000 (10 seconds). 145 146To ensure all the streams are interleaved correctly, libavformat will 147wait until it has at least one packet for each stream before actually 148writing any packets to the output file. When some streams are 149"sparse" (i.e. there are large gaps between successive packets), this 150can result in excessive buffering. 151 152This field specifies the maximum difference between the timestamps of the 153first and the last packet in the muxing queue, above which libavformat 154will output a packet regardless of whether it has queued a packet for all 155the streams. 156 157If set to 0, libavformat will continue buffering packets until it has 158a packet for each stream, regardless of the maximum timestamp 159difference between the buffered packets. 160 161@item use_wallclock_as_timestamps @var{integer} (@emph{input}) 162Use wallclock as timestamps if set to 1. Default is 0. 163 164@item avoid_negative_ts @var{integer} (@emph{output}) 165 166Possible values: 167@table @samp 168@item make_non_negative 169Shift timestamps to make them non-negative. 170Also note that this affects only leading negative timestamps, and not 171non-monotonic negative timestamps. 172@item make_zero 173Shift timestamps so that the first timestamp is 0. 174@item auto (default) 175Enables shifting when required by the target format. 176@item disabled 177Disables shifting of timestamp. 178@end table 179 180When shifting is enabled, all output timestamps are shifted by the 181same amount. Audio, video, and subtitles desynching and relative 182timestamp differences are preserved compared to how they would have 183been without shifting. 184 185@item skip_initial_bytes @var{integer} (@emph{input}) 186Set number of bytes to skip before reading header and frames if set to 1. 187Default is 0. 188 189@item correct_ts_overflow @var{integer} (@emph{input}) 190Correct single timestamp overflows if set to 1. Default is 1. 191 192@item flush_packets @var{integer} (@emph{output}) 193Flush the underlying I/O stream after each packet. Default is -1 (auto), which 194means that the underlying protocol will decide, 1 enables it, and has the 195effect of reducing the latency, 0 disables it and may increase IO throughput in 196some cases. 197 198@item output_ts_offset @var{offset} (@emph{output}) 199Set the output time offset. 200 201@var{offset} must be a time duration specification, 202see @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}. 203 204The offset is added by the muxer to the output timestamps. 205 206Specifying a positive offset means that the corresponding streams are 207delayed bt the time duration specified in @var{offset}. Default value 208is @code{0} (meaning that no offset is applied). 209 210@item format_whitelist @var{list} (@emph{input}) 211"," separated list of allowed demuxers. By default all are allowed. 212 213@item dump_separator @var{string} (@emph{input}) 214Separator used to separate the fields printed on the command line about the 215Stream parameters. 216For example, to separate the fields with newlines and indentation: 217@example 218ffprobe -dump_separator " 219 " -i ~/videos/matrixbench_mpeg2.mpg 220@end example 221 222@item max_streams @var{integer} (@emph{input}) 223Specifies the maximum number of streams. This can be used to reject files that 224would require too many resources due to a large number of streams. 225 226@item skip_estimate_duration_from_pts @var{bool} (@emph{input}) 227Skip estimation of input duration when calculated using PTS. 228At present, applicable for MPEG-PS and MPEG-TS. 229 230@item strict, f_strict @var{integer} (@emph{input/output}) 231Specify how strictly to follow the standards. @code{f_strict} is deprecated and 232should be used only via the @command{ffmpeg} tool. 233 234Possible values: 235@table @samp 236@item very 237strictly conform to an older more strict version of the spec or reference software 238@item strict 239strictly conform to all the things in the spec no matter what consequences 240@item normal 241 242@item unofficial 243allow unofficial extensions 244@item experimental 245allow non standardized experimental things, experimental 246(unfinished/work in progress/not well tested) decoders and encoders. 247Note: experimental decoders can pose a security risk, do not use this for 248decoding untrusted input. 249@end table 250 251@end table 252 253@c man end FORMAT OPTIONS 254 255@anchor{Format stream specifiers} 256@section Format stream specifiers 257 258Format stream specifiers allow selection of one or more streams that 259match specific properties. 260 261The exact semantics of stream specifiers is defined by the 262@code{avformat_match_stream_specifier()} function declared in the 263@file{libavformat/avformat.h} header and documented in the 264@ref{Stream specifiers,,Stream specifiers section in the ffmpeg(1) manual,ffmpeg}. 265 266@ifclear config-writeonly 267@include demuxers.texi 268@end ifclear 269@ifclear config-readonly 270@include muxers.texi 271@end ifclear 272@include metadata.texi 273