1 @chapter Format Options
2 @c man begin FORMAT OPTIONS
4 The libavformat library provides some generic global options, which
5 can be set on all the muxers and demuxers. In addition each muxer or
6 demuxer may support so-called private options, which are specific for
9 Options may be set by specifying -@var{option} @var{value} in the
10 FFmpeg tools, or by setting the value explicitly in the
11 @code{AVFormatContext} options or using the @file{libavutil/opt.h} API
14 The list of supported options follows:
17 @item avioflags @var{flags} (@emph{input/output})
24 @item probesize @var{integer} (@emph{input})
25 Set probing size in bytes, i.e. the size of the data to analyze to get
26 stream information. A higher value will enable detecting more
27 information in case it is dispersed into the stream, but will increase
28 latency. Must be an integer not lesser than 32. It is 5000000 by default.
30 @item max_probe_packets @var{integer} (@emph{input})
31 Set the maximum number of buffered packets when probing a codec.
32 Default is 2500 packets.
34 @item packetsize @var{integer} (@emph{output})
37 @item fflags @var{flags}
38 Set format flags. Some are implemented for a limited number of formats.
40 Possible values for input files:
43 Discard corrupted packets.
45 Enable fast, but inaccurate seeks for some formats.
47 Generate missing PTS if DTS is present.
49 Ignore DTS if PTS is set. Inert when nofillin is set.
52 @item keepside (@emph{deprecated},@emph{inert})
54 Reduce the latency introduced by buffering during initial input streams analysis.
56 Do not fill in missing values in packet fields that can be exactly calculated.
58 Disable AVParsers, this needs @code{+nofillin} too.
60 Try to interleave output packets by DTS. At present, available only for AVIs with an index.
63 Possible values for output files:
66 Automatically apply bitstream filters as required by the output format. Enabled by default.
68 Only write platform-, build- and time-independent data.
69 This ensures that file and data checksums are reproducible and match between
70 platforms. Its primary use is for regression testing.
72 Write out packets immediately.
73 @item latm (@emph{deprecated},@emph{inert})
75 Stop muxing at the end of the shortest stream.
76 It may be needed to increase max_interleave_delta to avoid flushing the longer
80 @item seek2any @var{integer} (@emph{input})
81 Allow seeking to non-keyframes on demuxer level when supported if set to 1.
84 @item analyzeduration @var{integer} (@emph{input})
85 Specify how many microseconds are analyzed to probe the input. A
86 higher value will enable detecting more accurate information, but will
87 increase latency. It defaults to 5,000,000 microseconds = 5 seconds.
89 @item cryptokey @var{hexadecimal string} (@emph{input})
92 @item indexmem @var{integer} (@emph{input})
93 Set max memory used for timestamp index (per stream).
95 @item rtbufsize @var{integer} (@emph{input})
96 Set max memory used for buffering real-time frames.
98 @item fdebug @var{flags} (@emph{input/output})
99 Print specific debug info.
106 @item max_delay @var{integer} (@emph{input/output})
107 Set maximum muxing or demuxing delay in microseconds.
109 @item fpsprobesize @var{integer} (@emph{input})
110 Set number of frames used to probe fps.
112 @item audio_preload @var{integer} (@emph{output})
113 Set microseconds by which audio packets should be interleaved earlier.
115 @item chunk_duration @var{integer} (@emph{output})
116 Set microseconds for each chunk.
118 @item chunk_size @var{integer} (@emph{output})
119 Set size in bytes for each chunk.
121 @item err_detect, f_err_detect @var{flags} (@emph{input})
122 Set error detection flags. @code{f_err_detect} is deprecated and
123 should be used only via the @command{ffmpeg} tool.
128 Verify embedded CRCs.
130 Detect bitstream specification deviations.
132 Detect improper bitstream length.
134 Abort decoding on minor error detection.
136 Consider things that violate the spec and have not been seen in the
139 Consider all spec non compliancies as errors.
141 Consider things that a sane encoder should not do as an error.
144 @item max_interleave_delta @var{integer} (@emph{output})
145 Set maximum buffering duration for interleaving. The duration is
146 expressed in microseconds, and defaults to 10000000 (10 seconds).
148 To ensure all the streams are interleaved correctly, libavformat will
149 wait until it has at least one packet for each stream before actually
150 writing any packets to the output file. When some streams are
151 "sparse" (i.e. there are large gaps between successive packets), this
152 can result in excessive buffering.
154 This field specifies the maximum difference between the timestamps of the
155 first and the last packet in the muxing queue, above which libavformat
156 will output a packet regardless of whether it has queued a packet for all
159 If set to 0, libavformat will continue buffering packets until it has
160 a packet for each stream, regardless of the maximum timestamp
161 difference between the buffered packets.
163 @item use_wallclock_as_timestamps @var{integer} (@emph{input})
164 Use wallclock as timestamps if set to 1. Default is 0.
166 @item avoid_negative_ts @var{integer} (@emph{output})
170 @item make_non_negative
171 Shift timestamps to make them non-negative.
172 Also note that this affects only leading negative timestamps, and not
173 non-monotonic negative timestamps.
175 Shift timestamps so that the first timestamp is 0.
177 Enables shifting when required by the target format.
179 Disables shifting of timestamp.
182 When shifting is enabled, all output timestamps are shifted by the
183 same amount. Audio, video, and subtitles desynching and relative
184 timestamp differences are preserved compared to how they would have
185 been without shifting.
187 @item skip_initial_bytes @var{integer} (@emph{input})
188 Set number of bytes to skip before reading header and frames if set to 1.
191 @item correct_ts_overflow @var{integer} (@emph{input})
192 Correct single timestamp overflows if set to 1. Default is 1.
194 @item flush_packets @var{integer} (@emph{output})
195 Flush the underlying I/O stream after each packet. Default is -1 (auto), which
196 means that the underlying protocol will decide, 1 enables it, and has the
197 effect of reducing the latency, 0 disables it and may increase IO throughput in
200 @item output_ts_offset @var{offset} (@emph{output})
201 Set the output time offset.
203 @var{offset} must be a time duration specification,
204 see @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}.
206 The offset is added by the muxer to the output timestamps.
208 Specifying a positive offset means that the corresponding streams are
209 delayed bt the time duration specified in @var{offset}. Default value
210 is @code{0} (meaning that no offset is applied).
212 @item format_whitelist @var{list} (@emph{input})
213 "," separated list of allowed demuxers. By default all are allowed.
215 @item dump_separator @var{string} (@emph{input})
216 Separator used to separate the fields printed on the command line about the
218 For example, to separate the fields with newlines and indentation:
220 ffprobe -dump_separator "
221 " -i ~/videos/matrixbench_mpeg2.mpg
224 @item max_streams @var{integer} (@emph{input})
225 Specifies the maximum number of streams. This can be used to reject files that
226 would require too many resources due to a large number of streams.
228 @item skip_estimate_duration_from_pts @var{bool} (@emph{input})
229 Skip estimation of input duration when calculated using PTS.
230 At present, applicable for MPEG-PS and MPEG-TS.
232 @item strict, f_strict @var{integer} (@emph{input/output})
233 Specify how strictly to follow the standards. @code{f_strict} is deprecated and
234 should be used only via the @command{ffmpeg} tool.
239 strictly conform to an older more strict version of the spec or reference software
241 strictly conform to all the things in the spec no matter what consequences
245 allow unofficial extensions
247 allow non standardized experimental things, experimental
248 (unfinished/work in progress/not well tested) decoders and encoders.
249 Note: experimental decoders can pose a security risk, do not use this for
250 decoding untrusted input.
255 @c man end FORMAT OPTIONS
257 @anchor{Format stream specifiers}
258 @section Format stream specifiers
260 Format stream specifiers allow selection of one or more streams that
261 match specific properties.
263 The 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}.
268 @ifclear config-writeonly
269 @include demuxers.texi
271 @ifclear config-readonly
274 @include metadata.texi