| 1 | @chapter Format Options |
| 2 | @c man begin FORMAT OPTIONS |
| 3 | |
| 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 |
| 7 | that component. |
| 8 | |
| 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 |
| 12 | for programmatic use. |
| 13 | |
| 14 | The list of supported options follows: |
| 15 | |
| 16 | @table @option |
| 17 | @item avioflags @var{flags} (@emph{input/output}) |
| 18 | Possible values: |
| 19 | @table @samp |
| 20 | @item direct |
| 21 | Reduce buffering. |
| 22 | @end table |
| 23 | |
| 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 allow to detect 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. |
| 29 | |
| 30 | @item packetsize @var{integer} (@emph{output}) |
| 31 | Set packet size. |
| 32 | |
| 33 | @item fflags @var{flags} (@emph{input/output}) |
| 34 | Set format flags. |
| 35 | |
| 36 | Possible values: |
| 37 | @table @samp |
| 38 | @item ignidx |
| 39 | Ignore index. |
| 40 | @item genpts |
| 41 | Generate PTS. |
| 42 | @item nofillin |
| 43 | Do not fill in missing values that can be exactly calculated. |
| 44 | @item noparse |
| 45 | Disable AVParsers, this needs @code{+nofillin} too. |
| 46 | @item igndts |
| 47 | Ignore DTS. |
| 48 | @item discardcorrupt |
| 49 | Discard corrupted frames. |
| 50 | @item sortdts |
| 51 | Try to interleave output packets by DTS. |
| 52 | @item keepside |
| 53 | Do not merge side data. |
| 54 | @item latm |
| 55 | Enable RTP MP4A-LATM payload. |
| 56 | @item nobuffer |
| 57 | Reduce the latency introduced by optional buffering |
| 58 | @end table |
| 59 | |
| 60 | @item seek2any @var{integer} (@emph{input}) |
| 61 | Allow seeking to non-keyframes on demuxer level when supported if set to 1. |
| 62 | Default is 0. |
| 63 | |
| 64 | @item analyzeduration @var{integer} (@emph{input}) |
| 65 | Specify how many microseconds are analyzed to probe the input. A |
| 66 | higher value will allow to detect more accurate information, but will |
| 67 | increase latency. It defaults to 5,000,000 microseconds = 5 seconds. |
| 68 | |
| 69 | @item cryptokey @var{hexadecimal string} (@emph{input}) |
| 70 | Set decryption key. |
| 71 | |
| 72 | @item indexmem @var{integer} (@emph{input}) |
| 73 | Set max memory used for timestamp index (per stream). |
| 74 | |
| 75 | @item rtbufsize @var{integer} (@emph{input}) |
| 76 | Set max memory used for buffering real-time frames. |
| 77 | |
| 78 | @item fdebug @var{flags} (@emph{input/output}) |
| 79 | Print specific debug info. |
| 80 | |
| 81 | Possible values: |
| 82 | @table @samp |
| 83 | @item ts |
| 84 | @end table |
| 85 | |
| 86 | @item max_delay @var{integer} (@emph{input/output}) |
| 87 | Set maximum muxing or demuxing delay in microseconds. |
| 88 | |
| 89 | @item fpsprobesize @var{integer} (@emph{input}) |
| 90 | Set number of frames used to probe fps. |
| 91 | |
| 92 | @item audio_preload @var{integer} (@emph{output}) |
| 93 | Set microseconds by which audio packets should be interleaved earlier. |
| 94 | |
| 95 | @item chunk_duration @var{integer} (@emph{output}) |
| 96 | Set microseconds for each chunk. |
| 97 | |
| 98 | @item chunk_size @var{integer} (@emph{output}) |
| 99 | Set size in bytes for each chunk. |
| 100 | |
| 101 | @item err_detect, f_err_detect @var{flags} (@emph{input}) |
| 102 | Set error detection flags. @code{f_err_detect} is deprecated and |
| 103 | should be used only via the @command{ffmpeg} tool. |
| 104 | |
| 105 | Possible values: |
| 106 | @table @samp |
| 107 | @item crccheck |
| 108 | Verify embedded CRCs. |
| 109 | @item bitstream |
| 110 | Detect bitstream specification deviations. |
| 111 | @item buffer |
| 112 | Detect improper bitstream length. |
| 113 | @item explode |
| 114 | Abort decoding on minor error detection. |
| 115 | @item careful |
| 116 | Consider things that violate the spec and have not been seen in the |
| 117 | wild as errors. |
| 118 | @item compliant |
| 119 | Consider all spec non compliancies as errors. |
| 120 | @item aggressive |
| 121 | Consider things that a sane encoder should not do as an error. |
| 122 | @end table |
| 123 | |
| 124 | @item use_wallclock_as_timestamps @var{integer} (@emph{input}) |
| 125 | Use wallclock as timestamps. |
| 126 | |
| 127 | @item avoid_negative_ts @var{integer} (@emph{output}) |
| 128 | |
| 129 | Possible values: |
| 130 | @table @samp |
| 131 | @item make_non_negative |
| 132 | Shift timestamps to make them non-negative. |
| 133 | Also note that this affects only leading negative timestamps, and not |
| 134 | non-monotonic negative timestamps. |
| 135 | @item make_zero |
| 136 | Shift timestamps so that the first timestamp is 0. |
| 137 | @item auto (default) |
| 138 | Enables shifting when required by the target format. |
| 139 | @item disabled |
| 140 | Disables shifting of timestamp. |
| 141 | @end table |
| 142 | |
| 143 | When shifting is enabled, all output timestamps are shifted by the |
| 144 | same amount. Audio, video, and subtitles desynching and relative |
| 145 | timestamp differences are preserved compared to how they would have |
| 146 | been without shifting. |
| 147 | |
| 148 | @item skip_initial_bytes @var{integer} (@emph{input}) |
| 149 | Set number of bytes to skip before reading header and frames if set to 1. |
| 150 | Default is 0. |
| 151 | |
| 152 | @item correct_ts_overflow @var{integer} (@emph{input}) |
| 153 | Correct single timestamp overflows if set to 1. Default is 1. |
| 154 | |
| 155 | @item flush_packets @var{integer} (@emph{output}) |
| 156 | Flush the underlying I/O stream after each packet. Default 1 enables it, and |
| 157 | has the effect of reducing the latency; 0 disables it and may slightly |
| 158 | increase performance in some cases. |
| 159 | |
| 160 | @item output_ts_offset @var{offset} (@emph{output}) |
| 161 | Set the output time offset. |
| 162 | |
| 163 | @var{offset} must be a time duration specification, |
| 164 | see @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}. |
| 165 | |
| 166 | The offset is added by the muxer to the output timestamps. |
| 167 | |
| 168 | Specifying a positive offset means that the corresponding streams are |
| 169 | delayed bt the time duration specified in @var{offset}. Default value |
| 170 | is @code{0} (meaning that no offset is applied). |
| 171 | @end table |
| 172 | |
| 173 | @c man end FORMAT OPTIONS |
| 174 | |
| 175 | @anchor{Format stream specifiers} |
| 176 | @section Format stream specifiers |
| 177 | |
| 178 | Format stream specifiers allow selection of one or more streams that |
| 179 | match specific properties. |
| 180 | |
| 181 | Possible forms of stream specifiers are: |
| 182 | @table @option |
| 183 | @item @var{stream_index} |
| 184 | Matches the stream with this index. |
| 185 | |
| 186 | @item @var{stream_type}[:@var{stream_index}] |
| 187 | @var{stream_type} is one of following: 'v' for video, 'a' for audio, |
| 188 | 's' for subtitle, 'd' for data, and 't' for attachments. If |
| 189 | @var{stream_index} is given, then it matches the stream number |
| 190 | @var{stream_index} of this type. Otherwise, it matches all streams of |
| 191 | this type. |
| 192 | |
| 193 | @item p:@var{program_id}[:@var{stream_index}] |
| 194 | If @var{stream_index} is given, then it matches the stream with number |
| 195 | @var{stream_index} in the program with the id |
| 196 | @var{program_id}. Otherwise, it matches all streams in the program. |
| 197 | |
| 198 | @item #@var{stream_id} |
| 199 | Matches the stream by a format-specific ID. |
| 200 | @end table |
| 201 | |
| 202 | The exact semantics of stream specifiers is defined by the |
| 203 | @code{avformat_match_stream_specifier()} function declared in the |
| 204 | @file{libavformat/avformat.h} header. |
| 205 | |
| 206 | @ifclear config-writeonly |
| 207 | @include demuxers.texi |
| 208 | @end ifclear |
| 209 | @ifclear config-readonly |
| 210 | @include muxers.texi |
| 211 | @end ifclear |
| 212 | @include metadata.texi |