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 keepside (@emph{deprecated},@emph{inert}) 53@item nobuffer 54Reduce the latency introduced by buffering during initial input streams analysis. 55@item nofillin 56Do not fill in missing values in packet fields that can be exactly calculated. 57@item noparse 58Disable AVParsers, this needs @code{+nofillin} too. 59@item sortdts 60Try to interleave output packets by DTS. At present, available only for AVIs with an index. 61@end table 62 63Possible values for output files: 64@table @samp 65@item autobsf 66Automatically apply bitstream filters as required by the output format. Enabled by default. 67@item bitexact 68Only write platform-, build- and time-independent data. 69This ensures that file and data checksums are reproducible and match between 70platforms. Its primary use is for regression testing. 71@item flush_packets 72Write out packets immediately. 73@item latm (@emph{deprecated},@emph{inert}) 74@item shortest 75Stop muxing at the end of the shortest stream. 76It may be needed to increase max_interleave_delta to avoid flushing the longer 77streams before EOF. 78@end table 79 80@item seek2any @var{integer} (@emph{input}) 81Allow seeking to non-keyframes on demuxer level when supported if set to 1. 82Default is 0. 83 84@item analyzeduration @var{integer} (@emph{input}) 85Specify how many microseconds are analyzed to probe the input. A 86higher value will enable detecting more accurate information, but will 87increase latency. It defaults to 5,000,000 microseconds = 5 seconds. 88 89@item cryptokey @var{hexadecimal string} (@emph{input}) 90Set decryption key. 91 92@item indexmem @var{integer} (@emph{input}) 93Set max memory used for timestamp index (per stream). 94 95@item rtbufsize @var{integer} (@emph{input}) 96Set max memory used for buffering real-time frames. 97 98@item fdebug @var{flags} (@emph{input/output}) 99Print specific debug info. 100 101Possible values: 102@table @samp 103@item ts 104@end table 105 106@item max_delay @var{integer} (@emph{input/output}) 107Set maximum muxing or demuxing delay in microseconds. 108 109@item fpsprobesize @var{integer} (@emph{input}) 110Set number of frames used to probe fps. 111 112@item audio_preload @var{integer} (@emph{output}) 113Set microseconds by which audio packets should be interleaved earlier. 114 115@item chunk_duration @var{integer} (@emph{output}) 116Set microseconds for each chunk. 117 118@item chunk_size @var{integer} (@emph{output}) 119Set size in bytes for each chunk. 120 121@item err_detect, f_err_detect @var{flags} (@emph{input}) 122Set error detection flags. @code{f_err_detect} is deprecated and 123should be used only via the @command{ffmpeg} tool. 124 125Possible values: 126@table @samp 127@item crccheck 128Verify embedded CRCs. 129@item bitstream 130Detect bitstream specification deviations. 131@item buffer 132Detect improper bitstream length. 133@item explode 134Abort decoding on minor error detection. 135@item careful 136Consider things that violate the spec and have not been seen in the 137wild as errors. 138@item compliant 139Consider all spec non compliancies as errors. 140@item aggressive 141Consider things that a sane encoder should not do as an error. 142@end table 143 144@item max_interleave_delta @var{integer} (@emph{output}) 145Set maximum buffering duration for interleaving. The duration is 146expressed in microseconds, and defaults to 10000000 (10 seconds). 147 148To ensure all the streams are interleaved correctly, libavformat will 149wait until it has at least one packet for each stream before actually 150writing any packets to the output file. When some streams are 151"sparse" (i.e. there are large gaps between successive packets), this 152can result in excessive buffering. 153 154This field specifies the maximum difference between the timestamps of the 155first and the last packet in the muxing queue, above which libavformat 156will output a packet regardless of whether it has queued a packet for all 157the streams. 158 159If set to 0, libavformat will continue buffering packets until it has 160a packet for each stream, regardless of the maximum timestamp 161difference between the buffered packets. 162 163@item use_wallclock_as_timestamps @var{integer} (@emph{input}) 164Use wallclock as timestamps if set to 1. Default is 0. 165 166@item avoid_negative_ts @var{integer} (@emph{output}) 167 168Possible values: 169@table @samp 170@item make_non_negative 171Shift timestamps to make them non-negative. 172Also note that this affects only leading negative timestamps, and not 173non-monotonic negative timestamps. 174@item make_zero 175Shift timestamps so that the first timestamp is 0. 176@item auto (default) 177Enables shifting when required by the target format. 178@item disabled 179Disables shifting of timestamp. 180@end table 181 182When shifting is enabled, all output timestamps are shifted by the 183same amount. Audio, video, and subtitles desynching and relative 184timestamp differences are preserved compared to how they would have 185been without shifting. 186 187@item skip_initial_bytes @var{integer} (@emph{input}) 188Set number of bytes to skip before reading header and frames if set to 1. 189Default is 0. 190 191@item correct_ts_overflow @var{integer} (@emph{input}) 192Correct single timestamp overflows if set to 1. Default is 1. 193 194@item flush_packets @var{integer} (@emph{output}) 195Flush the underlying I/O stream after each packet. Default is -1 (auto), which 196means that the underlying protocol will decide, 1 enables it, and has the 197effect of reducing the latency, 0 disables it and may increase IO throughput in 198some cases. 199 200@item output_ts_offset @var{offset} (@emph{output}) 201Set the output time offset. 202 203@var{offset} must be a time duration specification, 204see @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}. 205 206The offset is added by the muxer to the output timestamps. 207 208Specifying a positive offset means that the corresponding streams are 209delayed bt the time duration specified in @var{offset}. Default value 210is @code{0} (meaning that no offset is applied). 211 212@item format_whitelist @var{list} (@emph{input}) 213"," separated list of allowed demuxers. By default all are allowed. 214 215@item dump_separator @var{string} (@emph{input}) 216Separator used to separate the fields printed on the command line about the 217Stream parameters. 218For example, to separate the fields with newlines and indentation: 219@example 220ffprobe -dump_separator " 221 " -i ~/videos/matrixbench_mpeg2.mpg 222@end example 223 224@item max_streams @var{integer} (@emph{input}) 225Specifies the maximum number of streams. This can be used to reject files that 226would require too many resources due to a large number of streams. 227 228@item skip_estimate_duration_from_pts @var{bool} (@emph{input}) 229Skip estimation of input duration when calculated using PTS. 230At present, applicable for MPEG-PS and MPEG-TS. 231 232@item strict, f_strict @var{integer} (@emph{input/output}) 233Specify how strictly to follow the standards. @code{f_strict} is deprecated and 234should be used only via the @command{ffmpeg} tool. 235 236Possible values: 237@table @samp 238@item very 239strictly conform to an older more strict version of the spec or reference software 240@item strict 241strictly conform to all the things in the spec no matter what consequences 242@item normal 243 244@item unofficial 245allow unofficial extensions 246@item experimental 247allow non standardized experimental things, experimental 248(unfinished/work in progress/not well tested) decoders and encoders. 249Note: experimental decoders can pose a security risk, do not use this for 250decoding untrusted input. 251@end table 252 253@end table 254 255@c man end FORMAT OPTIONS 256 257@anchor{Format stream specifiers} 258@section Format stream specifiers 259 260Format stream specifiers allow selection of one or more streams that 261match specific properties. 262 263The exact semantics of stream specifiers is defined by the 264@code{avformat_match_stream_specifier()} function declared in the 265@file{libavformat/avformat.h} header and documented in the 266@ref{Stream specifiers,,Stream specifiers section in the ffmpeg(1) manual,ffmpeg}. 267 268@ifclear config-writeonly 269@include demuxers.texi 270@end ifclear 271@ifclear config-readonly 272@include muxers.texi 273@end ifclear 274@include metadata.texi 275