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 packetsize @var{integer} (@emph{output})
33 @item fflags @var{flags}
34 Set format flags. Some are implemented for a limited number of formats.
36 Possible values for input files:
39 Discard corrupted packets.
41 Enable fast, but inaccurate seeks for some formats.
43 Generate missing PTS if DTS is present.
45 Ignore DTS if PTS is set. Inert when nofillin is set.
48 @item keepside (@emph{deprecated},@emph{inert})
50 Reduce the latency introduced by buffering during initial input streams analysis.
52 Do not fill in missing values in packet fields that can be exactly calculated.
54 Disable AVParsers, this needs @code{+nofillin} too.
56 Try to interleave output packets by DTS. At present, available only for AVIs with an index.
59 Possible values for output files:
62 Automatically apply bitstream filters as required by the output format. Enabled by default.
64 Only write platform-, build- and time-independent data.
65 This ensures that file and data checksums are reproducible and match between
66 platforms. Its primary use is for regression testing.
68 Write out packets immediately.
69 @item latm (@emph{deprecated},@emph{inert})
71 Stop muxing at the end of the shortest stream.
72 It may be needed to increase max_interleave_delta to avoid flushing the longer
76 @item seek2any @var{integer} (@emph{input})
77 Allow seeking to non-keyframes on demuxer level when supported if set to 1.
80 @item analyzeduration @var{integer} (@emph{input})
81 Specify how many microseconds are analyzed to probe the input. A
82 higher value will enable detecting more accurate information, but will
83 increase latency. It defaults to 5,000,000 microseconds = 5 seconds.
85 @item cryptokey @var{hexadecimal string} (@emph{input})
88 @item indexmem @var{integer} (@emph{input})
89 Set max memory used for timestamp index (per stream).
91 @item rtbufsize @var{integer} (@emph{input})
92 Set max memory used for buffering real-time frames.
94 @item fdebug @var{flags} (@emph{input/output})
95 Print specific debug info.
102 @item max_delay @var{integer} (@emph{input/output})
103 Set maximum muxing or demuxing delay in microseconds.
105 @item fpsprobesize @var{integer} (@emph{input})
106 Set number of frames used to probe fps.
108 @item audio_preload @var{integer} (@emph{output})
109 Set microseconds by which audio packets should be interleaved earlier.
111 @item chunk_duration @var{integer} (@emph{output})
112 Set microseconds for each chunk.
114 @item chunk_size @var{integer} (@emph{output})
115 Set size in bytes for each chunk.
117 @item err_detect, f_err_detect @var{flags} (@emph{input})
118 Set error detection flags. @code{f_err_detect} is deprecated and
119 should be used only via the @command{ffmpeg} tool.
124 Verify embedded CRCs.
126 Detect bitstream specification deviations.
128 Detect improper bitstream length.
130 Abort decoding on minor error detection.
132 Consider things that violate the spec and have not been seen in the
135 Consider all spec non compliancies as errors.
137 Consider things that a sane encoder should not do as an error.
140 @item max_interleave_delta @var{integer} (@emph{output})
141 Set maximum buffering duration for interleaving. The duration is
142 expressed in microseconds, and defaults to 1000000 (1 second).
144 To ensure all the streams are interleaved correctly, libavformat will
145 wait until it has at least one packet for each stream before actually
146 writing any packets to the output file. When some streams are
147 "sparse" (i.e. there are large gaps between successive packets), this
148 can result in excessive buffering.
150 This field specifies the maximum difference between the timestamps of the
151 first and the last packet in the muxing queue, above which libavformat
152 will output a packet regardless of whether it has queued a packet for all
155 If set to 0, libavformat will continue buffering packets until it has
156 a packet for each stream, regardless of the maximum timestamp
157 difference between the buffered packets.
159 @item use_wallclock_as_timestamps @var{integer} (@emph{input})
160 Use wallclock as timestamps if set to 1. Default is 0.
162 @item avoid_negative_ts @var{integer} (@emph{output})
166 @item make_non_negative
167 Shift timestamps to make them non-negative.
168 Also note that this affects only leading negative timestamps, and not
169 non-monotonic negative timestamps.
171 Shift timestamps so that the first timestamp is 0.
173 Enables shifting when required by the target format.
175 Disables shifting of timestamp.
178 When shifting is enabled, all output timestamps are shifted by the
179 same amount. Audio, video, and subtitles desynching and relative
180 timestamp differences are preserved compared to how they would have
181 been without shifting.
183 @item skip_initial_bytes @var{integer} (@emph{input})
184 Set number of bytes to skip before reading header and frames if set to 1.
187 @item correct_ts_overflow @var{integer} (@emph{input})
188 Correct single timestamp overflows if set to 1. Default is 1.
190 @item flush_packets @var{integer} (@emph{output})
191 Flush the underlying I/O stream after each packet. Default is -1 (auto), which
192 means that the underlying protocol will decide, 1 enables it, and has the
193 effect of reducing the latency, 0 disables it and may increase IO throughput in
196 @item output_ts_offset @var{offset} (@emph{output})
197 Set the output time offset.
199 @var{offset} must be a time duration specification,
200 see @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}.
202 The offset is added by the muxer to the output timestamps.
204 Specifying a positive offset means that the corresponding streams are
205 delayed bt the time duration specified in @var{offset}. Default value
206 is @code{0} (meaning that no offset is applied).
208 @item format_whitelist @var{list} (@emph{input})
209 "," separated list of allowed demuxers. By default all are allowed.
211 @item dump_separator @var{string} (@emph{input})
212 Separator used to separate the fields printed on the command line about the
214 For example, to separate the fields with newlines and indentation:
216 ffprobe -dump_separator "
217 " -i ~/videos/matrixbench_mpeg2.mpg
220 @item max_streams @var{integer} (@emph{input})
221 Specifies the maximum number of streams. This can be used to reject files that
222 would require too many resources due to a large number of streams.
224 @item skip_estimate_duration_from_pts @var{bool} (@emph{input})
225 Skip estimation of input duration when calculated using PTS.
226 At present, applicable for MPEG-PS and MPEG-TS.
229 @c man end FORMAT OPTIONS
231 @anchor{Format stream specifiers}
232 @section Format stream specifiers
234 Format stream specifiers allow selection of one or more streams that
235 match specific properties.
237 Possible forms of stream specifiers are:
239 @item @var{stream_index}
240 Matches the stream with this index.
242 @item @var{stream_type}[:@var{stream_index}]
243 @var{stream_type} is one of following: 'v' for video, 'a' for audio,
244 's' for subtitle, 'd' for data, and 't' for attachments. If
245 @var{stream_index} is given, then it matches the stream number
246 @var{stream_index} of this type. Otherwise, it matches all streams of
249 @item p:@var{program_id}[:@var{stream_index}]
250 If @var{stream_index} is given, then it matches the stream with number
251 @var{stream_index} in the program with the id
252 @var{program_id}. Otherwise, it matches all streams in the program.
254 @item #@var{stream_id}
255 Matches the stream by a format-specific ID.
258 The exact semantics of stream specifiers is defined by the
259 @code{avformat_match_stream_specifier()} function declared in the
260 @file{libavformat/avformat.h} header.
262 @ifclear config-writeonly
263 @include demuxers.texi
265 @ifclear config-readonly
268 @include metadata.texi