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.
53 Reduce the latency introduced by buffering during initial input streams analysis.
55 Do not fill in missing values in packet fields that can be exactly calculated.
57 Disable AVParsers, this needs @code{+nofillin} too.
59 Try to interleave output packets by DTS. At present, available only for AVIs with an index.
62 Possible values for output files:
65 Automatically apply bitstream filters as required by the output format. Enabled by default.
67 Only write platform-, build- and time-independent data.
68 This ensures that file and data checksums are reproducible and match between
69 platforms. Its primary use is for regression testing.
71 Write out packets immediately.
73 Stop muxing at the end of the shortest stream.
74 It may be needed to increase max_interleave_delta to avoid flushing the longer
78 @item seek2any @var{integer} (@emph{input})
79 Allow seeking to non-keyframes on demuxer level when supported if set to 1.
82 @item analyzeduration @var{integer} (@emph{input})
83 Specify how many microseconds are analyzed to probe the input. A
84 higher value will enable detecting more accurate information, but will
85 increase latency. It defaults to 5,000,000 microseconds = 5 seconds.
87 @item cryptokey @var{hexadecimal string} (@emph{input})
90 @item indexmem @var{integer} (@emph{input})
91 Set max memory used for timestamp index (per stream).
93 @item rtbufsize @var{integer} (@emph{input})
94 Set max memory used for buffering real-time frames.
96 @item fdebug @var{flags} (@emph{input/output})
97 Print specific debug info.
104 @item max_delay @var{integer} (@emph{input/output})
105 Set maximum muxing or demuxing delay in microseconds.
107 @item fpsprobesize @var{integer} (@emph{input})
108 Set number of frames used to probe fps.
110 @item audio_preload @var{integer} (@emph{output})
111 Set microseconds by which audio packets should be interleaved earlier.
113 @item chunk_duration @var{integer} (@emph{output})
114 Set microseconds for each chunk.
116 @item chunk_size @var{integer} (@emph{output})
117 Set size in bytes for each chunk.
119 @item err_detect, f_err_detect @var{flags} (@emph{input})
120 Set error detection flags. @code{f_err_detect} is deprecated and
121 should be used only via the @command{ffmpeg} tool.
126 Verify embedded CRCs.
128 Detect bitstream specification deviations.
130 Detect improper bitstream length.
132 Abort decoding on minor error detection.
134 Consider things that violate the spec and have not been seen in the
137 Consider all spec non compliancies as errors.
139 Consider things that a sane encoder should not do as an error.
142 @item max_interleave_delta @var{integer} (@emph{output})
143 Set maximum buffering duration for interleaving. The duration is
144 expressed in microseconds, and defaults to 10000000 (10 seconds).
146 To ensure all the streams are interleaved correctly, libavformat will
147 wait until it has at least one packet for each stream before actually
148 writing any packets to the output file. When some streams are
149 "sparse" (i.e. there are large gaps between successive packets), this
150 can result in excessive buffering.
152 This field specifies the maximum difference between the timestamps of the
153 first and the last packet in the muxing queue, above which libavformat
154 will output a packet regardless of whether it has queued a packet for all
157 If set to 0, libavformat will continue buffering packets until it has
158 a packet for each stream, regardless of the maximum timestamp
159 difference between the buffered packets.
161 @item use_wallclock_as_timestamps @var{integer} (@emph{input})
162 Use wallclock as timestamps if set to 1. Default is 0.
164 @item avoid_negative_ts @var{integer} (@emph{output})
168 @item make_non_negative
169 Shift timestamps to make them non-negative.
170 Also note that this affects only leading negative timestamps, and not
171 non-monotonic negative timestamps.
173 Shift timestamps so that the first timestamp is 0.
175 Enables shifting when required by the target format.
177 Disables shifting of timestamp.
180 When shifting is enabled, all output timestamps are shifted by the
181 same amount. Audio, video, and subtitles desynching and relative
182 timestamp differences are preserved compared to how they would have
183 been without shifting.
185 @item skip_initial_bytes @var{integer} (@emph{input})
186 Set number of bytes to skip before reading header and frames if set to 1.
189 @item correct_ts_overflow @var{integer} (@emph{input})
190 Correct single timestamp overflows if set to 1. Default is 1.
192 @item flush_packets @var{integer} (@emph{output})
193 Flush the underlying I/O stream after each packet. Default is -1 (auto), which
194 means that the underlying protocol will decide, 1 enables it, and has the
195 effect of reducing the latency, 0 disables it and may increase IO throughput in
198 @item output_ts_offset @var{offset} (@emph{output})
199 Set the output time offset.
201 @var{offset} must be a time duration specification,
202 see @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}.
204 The offset is added by the muxer to the output timestamps.
206 Specifying a positive offset means that the corresponding streams are
207 delayed bt the time duration specified in @var{offset}. Default value
208 is @code{0} (meaning that no offset is applied).
210 @item format_whitelist @var{list} (@emph{input})
211 "," separated list of allowed demuxers. By default all are allowed.
213 @item dump_separator @var{string} (@emph{input})
214 Separator used to separate the fields printed on the command line about the
216 For example, to separate the fields with newlines and indentation:
218 ffprobe -dump_separator "
219 " -i ~/videos/matrixbench_mpeg2.mpg
222 @item max_streams @var{integer} (@emph{input})
223 Specifies the maximum number of streams. This can be used to reject files that
224 would require too many resources due to a large number of streams.
226 @item skip_estimate_duration_from_pts @var{bool} (@emph{input})
227 Skip estimation of input duration when calculated using PTS.
228 At present, applicable for MPEG-PS and MPEG-TS.
230 @item strict, f_strict @var{integer} (@emph{input/output})
231 Specify how strictly to follow the standards. @code{f_strict} is deprecated and
232 should be used only via the @command{ffmpeg} tool.
237 strictly conform to an older more strict version of the spec or reference software
239 strictly conform to all the things in the spec no matter what consequences
243 allow unofficial extensions
245 allow non standardized experimental things, experimental
246 (unfinished/work in progress/not well tested) decoders and encoders.
247 Note: experimental decoders can pose a security risk, do not use this for
248 decoding untrusted input.
253 @c man end FORMAT OPTIONS
255 @anchor{Format stream specifiers}
256 @section Format stream specifiers
258 Format stream specifiers allow selection of one or more streams that
259 match specific properties.
261 The 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}.
266 @ifclear config-writeonly
267 @include demuxers.texi
269 @ifclear config-readonly
272 @include metadata.texi