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} (@emph{input/output})
41 Enable fast, but inaccurate seeks for some formats.
45 Do not fill in missing values that can be exactly calculated.
47 Disable AVParsers, this needs @code{+nofillin} too.
51 Discard corrupted frames.
53 Try to interleave output packets by DTS.
55 Do not merge side data.
57 Enable RTP MP4A-LATM payload.
59 Reduce the latency introduced by optional buffering
61 Only write platform-, build- and time-independent data.
62 This ensures that file and data checksums are reproducible and match between
63 platforms. Its primary use is for regression testing.
66 @item seek2any @var{integer} (@emph{input})
67 Allow seeking to non-keyframes on demuxer level when supported if set to 1.
70 @item analyzeduration @var{integer} (@emph{input})
71 Specify how many microseconds are analyzed to probe the input. A
72 higher value will enable detecting more accurate information, but will
73 increase latency. It defaults to 5,000,000 microseconds = 5 seconds.
75 @item cryptokey @var{hexadecimal string} (@emph{input})
78 @item indexmem @var{integer} (@emph{input})
79 Set max memory used for timestamp index (per stream).
81 @item rtbufsize @var{integer} (@emph{input})
82 Set max memory used for buffering real-time frames.
84 @item fdebug @var{flags} (@emph{input/output})
85 Print specific debug info.
92 @item max_delay @var{integer} (@emph{input/output})
93 Set maximum muxing or demuxing delay in microseconds.
95 @item fpsprobesize @var{integer} (@emph{input})
96 Set number of frames used to probe fps.
98 @item audio_preload @var{integer} (@emph{output})
99 Set microseconds by which audio packets should be interleaved earlier.
101 @item chunk_duration @var{integer} (@emph{output})
102 Set microseconds for each chunk.
104 @item chunk_size @var{integer} (@emph{output})
105 Set size in bytes for each chunk.
107 @item err_detect, f_err_detect @var{flags} (@emph{input})
108 Set error detection flags. @code{f_err_detect} is deprecated and
109 should be used only via the @command{ffmpeg} tool.
114 Verify embedded CRCs.
116 Detect bitstream specification deviations.
118 Detect improper bitstream length.
120 Abort decoding on minor error detection.
122 Consider things that violate the spec and have not been seen in the
125 Consider all spec non compliancies as errors.
127 Consider things that a sane encoder should not do as an error.
130 @item use_wallclock_as_timestamps @var{integer} (@emph{input})
131 Use wallclock as timestamps.
133 @item avoid_negative_ts @var{integer} (@emph{output})
137 @item make_non_negative
138 Shift timestamps to make them non-negative.
139 Also note that this affects only leading negative timestamps, and not
140 non-monotonic negative timestamps.
142 Shift timestamps so that the first timestamp is 0.
144 Enables shifting when required by the target format.
146 Disables shifting of timestamp.
149 When shifting is enabled, all output timestamps are shifted by the
150 same amount. Audio, video, and subtitles desynching and relative
151 timestamp differences are preserved compared to how they would have
152 been without shifting.
154 @item skip_initial_bytes @var{integer} (@emph{input})
155 Set number of bytes to skip before reading header and frames if set to 1.
158 @item correct_ts_overflow @var{integer} (@emph{input})
159 Correct single timestamp overflows if set to 1. Default is 1.
161 @item flush_packets @var{integer} (@emph{output})
162 Flush the underlying I/O stream after each packet. Default 1 enables it, and
163 has the effect of reducing the latency; 0 disables it and may slightly
164 increase performance in some cases.
166 @item output_ts_offset @var{offset} (@emph{output})
167 Set the output time offset.
169 @var{offset} must be a time duration specification,
170 see @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}.
172 The offset is added by the muxer to the output timestamps.
174 Specifying a positive offset means that the corresponding streams are
175 delayed bt the time duration specified in @var{offset}. Default value
176 is @code{0} (meaning that no offset is applied).
178 @item format_whitelist @var{list} (@emph{input})
179 "," separated List of allowed demuxers. By default all are allowed.
181 @item dump_separator @var{string} (@emph{input})
182 Separator used to separate the fields printed on the command line about the
184 For example to separate the fields with newlines and indention:
186 ffprobe -dump_separator "
187 " -i ~/videos/matrixbench_mpeg2.mpg
191 @c man end FORMAT OPTIONS
193 @anchor{Format stream specifiers}
194 @section Format stream specifiers
196 Format stream specifiers allow selection of one or more streams that
197 match specific properties.
199 Possible forms of stream specifiers are:
201 @item @var{stream_index}
202 Matches the stream with this index.
204 @item @var{stream_type}[:@var{stream_index}]
205 @var{stream_type} is one of following: 'v' for video, 'a' for audio,
206 's' for subtitle, 'd' for data, and 't' for attachments. If
207 @var{stream_index} is given, then it matches the stream number
208 @var{stream_index} of this type. Otherwise, it matches all streams of
211 @item p:@var{program_id}[:@var{stream_index}]
212 If @var{stream_index} is given, then it matches the stream with number
213 @var{stream_index} in the program with the id
214 @var{program_id}. Otherwise, it matches all streams in the program.
216 @item #@var{stream_id}
217 Matches the stream by a format-specific ID.
220 The exact semantics of stream specifiers is defined by the
221 @code{avformat_match_stream_specifier()} function declared in the
222 @file{libavformat/avformat.h} header.
224 @ifclear config-writeonly
225 @include demuxers.texi
227 @ifclear config-readonly
230 @include metadata.texi