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  1. \input texinfo @c -*- texinfo -*-
  2. @documentencoding UTF-8
  3. @settitle ffmpeg Documentation
  4. @titlepage
  5. @center @titlefont{ffmpeg Documentation}
  6. @end titlepage
  7. @top
  8. @contents
  9. @chapter Synopsis
  10. ffmpeg [@var{global_options}] @{[@var{input_file_options}] -i @file{input_file}@} ... @{[@var{output_file_options}] @file{output_file}@} ...
  11. @chapter Description
  12. @c man begin DESCRIPTION
  13. @command{ffmpeg} is a very fast video and audio converter that can also grab from
  14. a live audio/video source. It can also convert between arbitrary sample
  15. rates and resize video on the fly with a high quality polyphase filter.
  16. @command{ffmpeg} reads from an arbitrary number of input "files" (which can be regular
  17. files, pipes, network streams, grabbing devices, etc.), specified by the
  18. @code{-i} option, and writes to an arbitrary number of output "files", which are
  19. specified by a plain output filename. Anything found on the command line which
  20. cannot be interpreted as an option is considered to be an output filename.
  21. Each input or output file can, in principle, contain any number of streams of
  22. different types (video/audio/subtitle/attachment/data). The allowed number and/or
  23. types of streams may be limited by the container format. Selecting which
  24. streams from which inputs will go into which output is either done automatically
  25. or with the @code{-map} option (see the Stream selection chapter).
  26. To refer to input files in options, you must use their indices (0-based). E.g.
  27. the first input file is @code{0}, the second is @code{1}, etc. Similarly, streams
  28. within a file are referred to by their indices. E.g. @code{2:3} refers to the
  29. fourth stream in the third input file. Also see the Stream specifiers chapter.
  30. As a general rule, options are applied to the next specified
  31. file. Therefore, order is important, and you can have the same
  32. option on the command line multiple times. Each occurrence is
  33. then applied to the next input or output file.
  34. Exceptions from this rule are the global options (e.g. verbosity level),
  35. which should be specified first.
  36. Do not mix input and output files -- first specify all input files, then all
  37. output files. Also do not mix options which belong to different files. All
  38. options apply ONLY to the next input or output file and are reset between files.
  39. @itemize
  40. @item
  41. To set the video bitrate of the output file to 64 kbit/s:
  42. @example
  43. ffmpeg -i input.avi -b:v 64k -bufsize 64k output.avi
  44. @end example
  45. @item
  46. To force the frame rate of the output file to 24 fps:
  47. @example
  48. ffmpeg -i input.avi -r 24 output.avi
  49. @end example
  50. @item
  51. To force the frame rate of the input file (valid for raw formats only)
  52. to 1 fps and the frame rate of the output file to 24 fps:
  53. @example
  54. ffmpeg -r 1 -i input.m2v -r 24 output.avi
  55. @end example
  56. @end itemize
  57. The format option may be needed for raw input files.
  58. @c man end DESCRIPTION
  59. @chapter Detailed description
  60. @c man begin DETAILED DESCRIPTION
  61. The transcoding process in @command{ffmpeg} for each output can be described by
  62. the following diagram:
  63. @verbatim
  64. _______ ______________
  65. | | | |
  66. | input | demuxer | encoded data | decoder
  67. | file | ---------> | packets | -----+
  68. |_______| |______________| |
  69. v
  70. _________
  71. | |
  72. | decoded |
  73. | frames |
  74. |_________|
  75. ________ ______________ |
  76. | | | | |
  77. | output | <-------- | encoded data | <----+
  78. | file | muxer | packets | encoder
  79. |________| |______________|
  80. @end verbatim
  81. @command{ffmpeg} calls the libavformat library (containing demuxers) to read
  82. input files and get packets containing encoded data from them. When there are
  83. multiple input files, @command{ffmpeg} tries to keep them synchronized by
  84. tracking lowest timestamp on any active input stream.
  85. Encoded packets are then passed to the decoder (unless streamcopy is selected
  86. for the stream, see further for a description). The decoder produces
  87. uncompressed frames (raw video/PCM audio/...) which can be processed further by
  88. filtering (see next section). After filtering, the frames are passed to the
  89. encoder, which encodes them and outputs encoded packets. Finally those are
  90. passed to the muxer, which writes the encoded packets to the output file.
  91. @section Filtering
  92. Before encoding, @command{ffmpeg} can process raw audio and video frames using
  93. filters from the libavfilter library. Several chained filters form a filter
  94. graph. @command{ffmpeg} distinguishes between two types of filtergraphs:
  95. simple and complex.
  96. @subsection Simple filtergraphs
  97. Simple filtergraphs are those that have exactly one input and output, both of
  98. the same type. In the above diagram they can be represented by simply inserting
  99. an additional step between decoding and encoding:
  100. @verbatim
  101. _________ ______________
  102. | | | |
  103. | decoded | | encoded data |
  104. | frames |\ _ | packets |
  105. |_________| \ /||______________|
  106. \ __________ /
  107. simple _\|| | / encoder
  108. filtergraph | filtered |/
  109. | frames |
  110. |__________|
  111. @end verbatim
  112. Simple filtergraphs are configured with the per-stream @option{-filter} option
  113. (with @option{-vf} and @option{-af} aliases for video and audio respectively).
  114. A simple filtergraph for video can look for example like this:
  115. @verbatim
  116. _______ _____________ _______ ________
  117. | | | | | | | |
  118. | input | ---> | deinterlace | ---> | scale | ---> | output |
  119. |_______| |_____________| |_______| |________|
  120. @end verbatim
  121. Note that some filters change frame properties but not frame contents. E.g. the
  122. @code{fps} filter in the example above changes number of frames, but does not
  123. touch the frame contents. Another example is the @code{setpts} filter, which
  124. only sets timestamps and otherwise passes the frames unchanged.
  125. @subsection Complex filtergraphs
  126. Complex filtergraphs are those which cannot be described as simply a linear
  127. processing chain applied to one stream. This is the case, for example, when the graph has
  128. more than one input and/or output, or when output stream type is different from
  129. input. They can be represented with the following diagram:
  130. @verbatim
  131. _________
  132. | |
  133. | input 0 |\ __________
  134. |_________| \ | |
  135. \ _________ /| output 0 |
  136. \ | | / |__________|
  137. _________ \| complex | /
  138. | | | |/
  139. | input 1 |---->| filter |\
  140. |_________| | | \ __________
  141. /| graph | \ | |
  142. / | | \| output 1 |
  143. _________ / |_________| |__________|
  144. | | /
  145. | input 2 |/
  146. |_________|
  147. @end verbatim
  148. Complex filtergraphs are configured with the @option{-filter_complex} option.
  149. Note that this option is global, since a complex filtergraph, by its nature,
  150. cannot be unambiguously associated with a single stream or file.
  151. The @option{-lavfi} option is equivalent to @option{-filter_complex}.
  152. A trivial example of a complex filtergraph is the @code{overlay} filter, which
  153. has two video inputs and one video output, containing one video overlaid on top
  154. of the other. Its audio counterpart is the @code{amix} filter.
  155. @section Stream copy
  156. Stream copy is a mode selected by supplying the @code{copy} parameter to the
  157. @option{-codec} option. It makes @command{ffmpeg} omit the decoding and encoding
  158. step for the specified stream, so it does only demuxing and muxing. It is useful
  159. for changing the container format or modifying container-level metadata. The
  160. diagram above will, in this case, simplify to this:
  161. @verbatim
  162. _______ ______________ ________
  163. | | | | | |
  164. | input | demuxer | encoded data | muxer | output |
  165. | file | ---------> | packets | -------> | file |
  166. |_______| |______________| |________|
  167. @end verbatim
  168. Since there is no decoding or encoding, it is very fast and there is no quality
  169. loss. However, it might not work in some cases because of many factors. Applying
  170. filters is obviously also impossible, since filters work on uncompressed data.
  171. @c man end DETAILED DESCRIPTION
  172. @chapter Stream selection
  173. @c man begin STREAM SELECTION
  174. By default, @command{ffmpeg} includes only one stream of each type (video, audio, subtitle)
  175. present in the input files and adds them to each output file. It picks the
  176. "best" of each based upon the following criteria: for video, it is the stream
  177. with the highest resolution, for audio, it is the stream with the most channels, for
  178. subtitles, it is the first subtitle stream. In the case where several streams of
  179. the same type rate equally, the stream with the lowest index is chosen.
  180. You can disable some of those defaults by using the @code{-vn/-an/-sn} options. For
  181. full manual control, use the @code{-map} option, which disables the defaults just
  182. described.
  183. @c man end STREAM SELECTION
  184. @chapter Options
  185. @c man begin OPTIONS
  186. @include fftools-common-opts.texi
  187. @section Main options
  188. @table @option
  189. @item -f @var{fmt} (@emph{input/output})
  190. Force input or output file format. The format is normally auto detected for input
  191. files and guessed from the file extension for output files, so this option is not
  192. needed in most cases.
  193. @item -i @var{filename} (@emph{input})
  194. input file name
  195. @item -y (@emph{global})
  196. Overwrite output files without asking.
  197. @item -n (@emph{global})
  198. Do not overwrite output files, and exit immediately if a specified
  199. output file already exists.
  200. @item -stream_loop @var{number} (@emph{input})
  201. Set number of times input stream shall be looped.
  202. @item -c[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
  203. @itemx -codec[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
  204. Select an encoder (when used before an output file) or a decoder (when used
  205. before an input file) for one or more streams. @var{codec} is the name of a
  206. decoder/encoder or a special value @code{copy} (output only) to indicate that
  207. the stream is not to be re-encoded.
  208. For example
  209. @example
  210. ffmpeg -i INPUT -map 0 -c:v libx264 -c:a copy OUTPUT
  211. @end example
  212. encodes all video streams with libx264 and copies all audio streams.
  213. For each stream, the last matching @code{c} option is applied, so
  214. @example
  215. ffmpeg -i INPUT -map 0 -c copy -c:v:1 libx264 -c:a:137 libvorbis OUTPUT
  216. @end example
  217. will copy all the streams except the second video, which will be encoded with
  218. libx264, and the 138th audio, which will be encoded with libvorbis.
  219. @item -t @var{duration} (@emph{input/output})
  220. When used as an input option (before @code{-i}), limit the @var{duration} of
  221. data read from the input file.
  222. When used as an output option (before an output filename), stop writing the
  223. output after its duration reaches @var{duration}.
  224. @var{duration} must be a time duration specification,
  225. see @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}.
  226. -to and -t are mutually exclusive and -t has priority.
  227. @item -to @var{position} (@emph{output})
  228. Stop writing the output at @var{position}.
  229. @var{position} must be a time duration specification,
  230. see @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}.
  231. -to and -t are mutually exclusive and -t has priority.
  232. @item -fs @var{limit_size} (@emph{output})
  233. Set the file size limit, expressed in bytes.
  234. @item -ss @var{position} (@emph{input/output})
  235. When used as an input option (before @code{-i}), seeks in this input file to
  236. @var{position}. Note that in most formats it is not possible to seek exactly,
  237. so @command{ffmpeg} will seek to the closest seek point before @var{position}.
  238. When transcoding and @option{-accurate_seek} is enabled (the default), this
  239. extra segment between the seek point and @var{position} will be decoded and
  240. discarded. When doing stream copy or when @option{-noaccurate_seek} is used, it
  241. will be preserved.
  242. When used as an output option (before an output filename), decodes but discards
  243. input until the timestamps reach @var{position}.
  244. @var{position} must be a time duration specification,
  245. see @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}.
  246. @item -sseof @var{position} (@emph{input/output})
  247. Like the @code{-ss} option but relative to the "end of file". That is negative
  248. values are earlier in the file, 0 is at EOF.
  249. @item -itsoffset @var{offset} (@emph{input})
  250. Set the input time offset.
  251. @var{offset} must be a time duration specification,
  252. see @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}.
  253. The offset is added to the timestamps of the input files. Specifying
  254. a positive offset means that the corresponding streams are delayed by
  255. the time duration specified in @var{offset}.
  256. @item -timestamp @var{date} (@emph{output})
  257. Set the recording timestamp in the container.
  258. @var{date} must be a date specification,
  259. see @ref{date syntax,,the Date section in the ffmpeg-utils(1) manual,ffmpeg-utils}.
  260. @item -metadata[:metadata_specifier] @var{key}=@var{value} (@emph{output,per-metadata})
  261. Set a metadata key/value pair.
  262. An optional @var{metadata_specifier} may be given to set metadata
  263. on streams or chapters. See @code{-map_metadata} documentation for
  264. details.
  265. This option overrides metadata set with @code{-map_metadata}. It is
  266. also possible to delete metadata by using an empty value.
  267. For example, for setting the title in the output file:
  268. @example
  269. ffmpeg -i in.avi -metadata title="my title" out.flv
  270. @end example
  271. To set the language of the first audio stream:
  272. @example
  273. ffmpeg -i INPUT -metadata:s:a:0 language=eng OUTPUT
  274. @end example
  275. @item -target @var{type} (@emph{output})
  276. Specify target file type (@code{vcd}, @code{svcd}, @code{dvd}, @code{dv},
  277. @code{dv50}). @var{type} may be prefixed with @code{pal-}, @code{ntsc-} or
  278. @code{film-} to use the corresponding standard. All the format options
  279. (bitrate, codecs, buffer sizes) are then set automatically. You can just type:
  280. @example
  281. ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
  282. @end example
  283. Nevertheless you can specify additional options as long as you know
  284. they do not conflict with the standard, as in:
  285. @example
  286. ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
  287. @end example
  288. @item -dframes @var{number} (@emph{output})
  289. Set the number of data frames to output. This is an alias for @code{-frames:d}.
  290. @item -frames[:@var{stream_specifier}] @var{framecount} (@emph{output,per-stream})
  291. Stop writing to the stream after @var{framecount} frames.
  292. @item -q[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
  293. @itemx -qscale[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
  294. Use fixed quality scale (VBR). The meaning of @var{q}/@var{qscale} is
  295. codec-dependent.
  296. If @var{qscale} is used without a @var{stream_specifier} then it applies only
  297. to the video stream, this is to maintain compatibility with previous behavior
  298. and as specifying the same codec specific value to 2 different codecs that is
  299. audio and video generally is not what is intended when no stream_specifier is
  300. used.
  301. @anchor{filter_option}
  302. @item -filter[:@var{stream_specifier}] @var{filtergraph} (@emph{output,per-stream})
  303. Create the filtergraph specified by @var{filtergraph} and use it to
  304. filter the stream.
  305. @var{filtergraph} is a description of the filtergraph to apply to
  306. the stream, and must have a single input and a single output of the
  307. same type of the stream. In the filtergraph, the input is associated
  308. to the label @code{in}, and the output to the label @code{out}. See
  309. the ffmpeg-filters manual for more information about the filtergraph
  310. syntax.
  311. See the @ref{filter_complex_option,,-filter_complex option} if you
  312. want to create filtergraphs with multiple inputs and/or outputs.
  313. @item -filter_script[:@var{stream_specifier}] @var{filename} (@emph{output,per-stream})
  314. This option is similar to @option{-filter}, the only difference is that its
  315. argument is the name of the file from which a filtergraph description is to be
  316. read.
  317. @item -pre[:@var{stream_specifier}] @var{preset_name} (@emph{output,per-stream})
  318. Specify the preset for matching stream(s).
  319. @item -stats (@emph{global})
  320. Print encoding progress/statistics. It is on by default, to explicitly
  321. disable it you need to specify @code{-nostats}.
  322. @item -progress @var{url} (@emph{global})
  323. Send program-friendly progress information to @var{url}.
  324. Progress information is written approximately every second and at the end of
  325. the encoding process. It is made of "@var{key}=@var{value}" lines. @var{key}
  326. consists of only alphanumeric characters. The last key of a sequence of
  327. progress information is always "progress".
  328. @item -stdin
  329. Enable interaction on standard input. On by default unless standard input is
  330. used as an input. To explicitly disable interaction you need to specify
  331. @code{-nostdin}.
  332. Disabling interaction on standard input is useful, for example, if
  333. ffmpeg is in the background process group. Roughly the same result can
  334. be achieved with @code{ffmpeg ... < /dev/null} but it requires a
  335. shell.
  336. @item -debug_ts (@emph{global})
  337. Print timestamp information. It is off by default. This option is
  338. mostly useful for testing and debugging purposes, and the output
  339. format may change from one version to another, so it should not be
  340. employed by portable scripts.
  341. See also the option @code{-fdebug ts}.
  342. @item -attach @var{filename} (@emph{output})
  343. Add an attachment to the output file. This is supported by a few formats
  344. like Matroska for e.g. fonts used in rendering subtitles. Attachments
  345. are implemented as a specific type of stream, so this option will add
  346. a new stream to the file. It is then possible to use per-stream options
  347. on this stream in the usual way. Attachment streams created with this
  348. option will be created after all the other streams (i.e. those created
  349. with @code{-map} or automatic mappings).
  350. Note that for Matroska you also have to set the mimetype metadata tag:
  351. @example
  352. ffmpeg -i INPUT -attach DejaVuSans.ttf -metadata:s:2 mimetype=application/x-truetype-font out.mkv
  353. @end example
  354. (assuming that the attachment stream will be third in the output file).
  355. @item -dump_attachment[:@var{stream_specifier}] @var{filename} (@emph{input,per-stream})
  356. Extract the matching attachment stream into a file named @var{filename}. If
  357. @var{filename} is empty, then the value of the @code{filename} metadata tag
  358. will be used.
  359. E.g. to extract the first attachment to a file named 'out.ttf':
  360. @example
  361. ffmpeg -dump_attachment:t:0 out.ttf -i INPUT
  362. @end example
  363. To extract all attachments to files determined by the @code{filename} tag:
  364. @example
  365. ffmpeg -dump_attachment:t "" -i INPUT
  366. @end example
  367. Technical note -- attachments are implemented as codec extradata, so this
  368. option can actually be used to extract extradata from any stream, not just
  369. attachments.
  370. @item -noautorotate
  371. Disable automatically rotating video based on file metadata.
  372. @end table
  373. @section Video Options
  374. @table @option
  375. @item -vframes @var{number} (@emph{output})
  376. Set the number of video frames to output. This is an alias for @code{-frames:v}.
  377. @item -r[:@var{stream_specifier}] @var{fps} (@emph{input/output,per-stream})
  378. Set frame rate (Hz value, fraction or abbreviation).
  379. As an input option, ignore any timestamps stored in the file and instead
  380. generate timestamps assuming constant frame rate @var{fps}.
  381. This is not the same as the @option{-framerate} option used for some input formats
  382. like image2 or v4l2 (it used to be the same in older versions of FFmpeg).
  383. If in doubt use @option{-framerate} instead of the input option @option{-r}.
  384. As an output option, duplicate or drop input frames to achieve constant output
  385. frame rate @var{fps}.
  386. @item -s[:@var{stream_specifier}] @var{size} (@emph{input/output,per-stream})
  387. Set frame size.
  388. As an input option, this is a shortcut for the @option{video_size} private
  389. option, recognized by some demuxers for which the frame size is either not
  390. stored in the file or is configurable -- e.g. raw video or video grabbers.
  391. As an output option, this inserts the @code{scale} video filter to the
  392. @emph{end} of the corresponding filtergraph. Please use the @code{scale} filter
  393. directly to insert it at the beginning or some other place.
  394. The format is @samp{wxh} (default - same as source).
  395. @item -aspect[:@var{stream_specifier}] @var{aspect} (@emph{output,per-stream})
  396. Set the video display aspect ratio specified by @var{aspect}.
  397. @var{aspect} can be a floating point number string, or a string of the
  398. form @var{num}:@var{den}, where @var{num} and @var{den} are the
  399. numerator and denominator of the aspect ratio. For example "4:3",
  400. "16:9", "1.3333", and "1.7777" are valid argument values.
  401. If used together with @option{-vcodec copy}, it will affect the aspect ratio
  402. stored at container level, but not the aspect ratio stored in encoded
  403. frames, if it exists.
  404. @item -vn (@emph{output})
  405. Disable video recording.
  406. @item -vcodec @var{codec} (@emph{output})
  407. Set the video codec. This is an alias for @code{-codec:v}.
  408. @item -pass[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
  409. Select the pass number (1 or 2). It is used to do two-pass
  410. video encoding. The statistics of the video are recorded in the first
  411. pass into a log file (see also the option -passlogfile),
  412. and in the second pass that log file is used to generate the video
  413. at the exact requested bitrate.
  414. On pass 1, you may just deactivate audio and set output to null,
  415. examples for Windows and Unix:
  416. @example
  417. ffmpeg -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y NUL
  418. ffmpeg -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null
  419. @end example
  420. @item -passlogfile[:@var{stream_specifier}] @var{prefix} (@emph{output,per-stream})
  421. Set two-pass log file name prefix to @var{prefix}, the default file name
  422. prefix is ``ffmpeg2pass''. The complete file name will be
  423. @file{PREFIX-N.log}, where N is a number specific to the output
  424. stream
  425. @item -vf @var{filtergraph} (@emph{output})
  426. Create the filtergraph specified by @var{filtergraph} and use it to
  427. filter the stream.
  428. This is an alias for @code{-filter:v}, see the @ref{filter_option,,-filter option}.
  429. @end table
  430. @section Advanced Video options
  431. @table @option
  432. @item -pix_fmt[:@var{stream_specifier}] @var{format} (@emph{input/output,per-stream})
  433. Set pixel format. Use @code{-pix_fmts} to show all the supported
  434. pixel formats.
  435. If the selected pixel format can not be selected, ffmpeg will print a
  436. warning and select the best pixel format supported by the encoder.
  437. If @var{pix_fmt} is prefixed by a @code{+}, ffmpeg will exit with an error
  438. if the requested pixel format can not be selected, and automatic conversions
  439. inside filtergraphs are disabled.
  440. If @var{pix_fmt} is a single @code{+}, ffmpeg selects the same pixel format
  441. as the input (or graph output) and automatic conversions are disabled.
  442. @item -sws_flags @var{flags} (@emph{input/output})
  443. Set SwScaler flags.
  444. @item -vdt @var{n}
  445. Discard threshold.
  446. @item -rc_override[:@var{stream_specifier}] @var{override} (@emph{output,per-stream})
  447. Rate control override for specific intervals, formatted as "int,int,int"
  448. list separated with slashes. Two first values are the beginning and
  449. end frame numbers, last one is quantizer to use if positive, or quality
  450. factor if negative.
  451. @item -ilme
  452. Force interlacing support in encoder (MPEG-2 and MPEG-4 only).
  453. Use this option if your input file is interlaced and you want
  454. to keep the interlaced format for minimum losses.
  455. The alternative is to deinterlace the input stream with
  456. @option{-deinterlace}, but deinterlacing introduces losses.
  457. @item -psnr
  458. Calculate PSNR of compressed frames.
  459. @item -vstats
  460. Dump video coding statistics to @file{vstats_HHMMSS.log}.
  461. @item -vstats_file @var{file}
  462. Dump video coding statistics to @var{file}.
  463. @item -top[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
  464. top=1/bottom=0/auto=-1 field first
  465. @item -dc @var{precision}
  466. Intra_dc_precision.
  467. @item -vtag @var{fourcc/tag} (@emph{output})
  468. Force video tag/fourcc. This is an alias for @code{-tag:v}.
  469. @item -qphist (@emph{global})
  470. Show QP histogram
  471. @item -vbsf @var{bitstream_filter}
  472. Deprecated see -bsf
  473. @item -force_key_frames[:@var{stream_specifier}] @var{time}[,@var{time}...] (@emph{output,per-stream})
  474. @item -force_key_frames[:@var{stream_specifier}] expr:@var{expr} (@emph{output,per-stream})
  475. Force key frames at the specified timestamps, more precisely at the first
  476. frames after each specified time.
  477. If the argument is prefixed with @code{expr:}, the string @var{expr}
  478. is interpreted like an expression and is evaluated for each frame. A
  479. key frame is forced in case the evaluation is non-zero.
  480. If one of the times is "@code{chapters}[@var{delta}]", it is expanded into
  481. the time of the beginning of all chapters in the file, shifted by
  482. @var{delta}, expressed as a time in seconds.
  483. This option can be useful to ensure that a seek point is present at a
  484. chapter mark or any other designated place in the output file.
  485. For example, to insert a key frame at 5 minutes, plus key frames 0.1 second
  486. before the beginning of every chapter:
  487. @example
  488. -force_key_frames 0:05:00,chapters-0.1
  489. @end example
  490. The expression in @var{expr} can contain the following constants:
  491. @table @option
  492. @item n
  493. the number of current processed frame, starting from 0
  494. @item n_forced
  495. the number of forced frames
  496. @item prev_forced_n
  497. the number of the previous forced frame, it is @code{NAN} when no
  498. keyframe was forced yet
  499. @item prev_forced_t
  500. the time of the previous forced frame, it is @code{NAN} when no
  501. keyframe was forced yet
  502. @item t
  503. the time of the current processed frame
  504. @end table
  505. For example to force a key frame every 5 seconds, you can specify:
  506. @example
  507. -force_key_frames expr:gte(t,n_forced*5)
  508. @end example
  509. To force a key frame 5 seconds after the time of the last forced one,
  510. starting from second 13:
  511. @example
  512. -force_key_frames expr:if(isnan(prev_forced_t),gte(t,13),gte(t,prev_forced_t+5))
  513. @end example
  514. Note that forcing too many keyframes is very harmful for the lookahead
  515. algorithms of certain encoders: using fixed-GOP options or similar
  516. would be more efficient.
  517. @item -copyinkf[:@var{stream_specifier}] (@emph{output,per-stream})
  518. When doing stream copy, copy also non-key frames found at the
  519. beginning.
  520. @item -hwaccel[:@var{stream_specifier}] @var{hwaccel} (@emph{input,per-stream})
  521. Use hardware acceleration to decode the matching stream(s). The allowed values
  522. of @var{hwaccel} are:
  523. @table @option
  524. @item none
  525. Do not use any hardware acceleration (the default).
  526. @item auto
  527. Automatically select the hardware acceleration method.
  528. @item vda
  529. Use Apple VDA hardware acceleration.
  530. @item vdpau
  531. Use VDPAU (Video Decode and Presentation API for Unix) hardware acceleration.
  532. @item dxva2
  533. Use DXVA2 (DirectX Video Acceleration) hardware acceleration.
  534. @item qsv
  535. Use the Intel QuickSync Video acceleration for video transcoding.
  536. Unlike most other values, this option does not enable accelerated decoding (that
  537. is used automatically whenever a qsv decoder is selected), but accelerated
  538. transcoding, without copying the frames into the system memory.
  539. For it to work, both the decoder and the encoder must support QSV acceleration
  540. and no filters must be used.
  541. @end table
  542. This option has no effect if the selected hwaccel is not available or not
  543. supported by the chosen decoder.
  544. Note that most acceleration methods are intended for playback and will not be
  545. faster than software decoding on modern CPUs. Additionally, @command{ffmpeg}
  546. will usually need to copy the decoded frames from the GPU memory into the system
  547. memory, resulting in further performance loss. This option is thus mainly
  548. useful for testing.
  549. @item -hwaccel_device[:@var{stream_specifier}] @var{hwaccel_device} (@emph{input,per-stream})
  550. Select a device to use for hardware acceleration.
  551. This option only makes sense when the @option{-hwaccel} option is also
  552. specified. Its exact meaning depends on the specific hardware acceleration
  553. method chosen.
  554. @table @option
  555. @item vdpau
  556. For VDPAU, this option specifies the X11 display/screen to use. If this option
  557. is not specified, the value of the @var{DISPLAY} environment variable is used
  558. @item dxva2
  559. For DXVA2, this option should contain the number of the display adapter to use.
  560. If this option is not specified, the default adapter is used.
  561. @item qsv
  562. For QSV, this option corresponds to the valus of MFX_IMPL_* . Allowed values
  563. are:
  564. @table @option
  565. @item auto
  566. @item sw
  567. @item hw
  568. @item auto_any
  569. @item hw_any
  570. @item hw2
  571. @item hw3
  572. @item hw4
  573. @end table
  574. @end table
  575. @item -hwaccels
  576. List all hardware acceleration methods supported in this build of ffmpeg.
  577. @end table
  578. @section Audio Options
  579. @table @option
  580. @item -aframes @var{number} (@emph{output})
  581. Set the number of audio frames to output. This is an alias for @code{-frames:a}.
  582. @item -ar[:@var{stream_specifier}] @var{freq} (@emph{input/output,per-stream})
  583. Set the audio sampling frequency. For output streams it is set by
  584. default to the frequency of the corresponding input stream. For input
  585. streams this option only makes sense for audio grabbing devices and raw
  586. demuxers and is mapped to the corresponding demuxer options.
  587. @item -aq @var{q} (@emph{output})
  588. Set the audio quality (codec-specific, VBR). This is an alias for -q:a.
  589. @item -ac[:@var{stream_specifier}] @var{channels} (@emph{input/output,per-stream})
  590. Set the number of audio channels. For output streams it is set by
  591. default to the number of input audio channels. For input streams
  592. this option only makes sense for audio grabbing devices and raw demuxers
  593. and is mapped to the corresponding demuxer options.
  594. @item -an (@emph{output})
  595. Disable audio recording.
  596. @item -acodec @var{codec} (@emph{input/output})
  597. Set the audio codec. This is an alias for @code{-codec:a}.
  598. @item -sample_fmt[:@var{stream_specifier}] @var{sample_fmt} (@emph{output,per-stream})
  599. Set the audio sample format. Use @code{-sample_fmts} to get a list
  600. of supported sample formats.
  601. @item -af @var{filtergraph} (@emph{output})
  602. Create the filtergraph specified by @var{filtergraph} and use it to
  603. filter the stream.
  604. This is an alias for @code{-filter:a}, see the @ref{filter_option,,-filter option}.
  605. @end table
  606. @section Advanced Audio options
  607. @table @option
  608. @item -atag @var{fourcc/tag} (@emph{output})
  609. Force audio tag/fourcc. This is an alias for @code{-tag:a}.
  610. @item -absf @var{bitstream_filter}
  611. Deprecated, see -bsf
  612. @item -guess_layout_max @var{channels} (@emph{input,per-stream})
  613. If some input channel layout is not known, try to guess only if it
  614. corresponds to at most the specified number of channels. For example, 2
  615. tells to @command{ffmpeg} to recognize 1 channel as mono and 2 channels as
  616. stereo but not 6 channels as 5.1. The default is to always try to guess. Use
  617. 0 to disable all guessing.
  618. @end table
  619. @section Subtitle options
  620. @table @option
  621. @item -scodec @var{codec} (@emph{input/output})
  622. Set the subtitle codec. This is an alias for @code{-codec:s}.
  623. @item -sn (@emph{output})
  624. Disable subtitle recording.
  625. @item -sbsf @var{bitstream_filter}
  626. Deprecated, see -bsf
  627. @end table
  628. @section Advanced Subtitle options
  629. @table @option
  630. @item -fix_sub_duration
  631. Fix subtitles durations. For each subtitle, wait for the next packet in the
  632. same stream and adjust the duration of the first to avoid overlap. This is
  633. necessary with some subtitles codecs, especially DVB subtitles, because the
  634. duration in the original packet is only a rough estimate and the end is
  635. actually marked by an empty subtitle frame. Failing to use this option when
  636. necessary can result in exaggerated durations or muxing failures due to
  637. non-monotonic timestamps.
  638. Note that this option will delay the output of all data until the next
  639. subtitle packet is decoded: it may increase memory consumption and latency a
  640. lot.
  641. @item -canvas_size @var{size}
  642. Set the size of the canvas used to render subtitles.
  643. @end table
  644. @section Advanced options
  645. @table @option
  646. @item -map [-]@var{input_file_id}[:@var{stream_specifier}][,@var{sync_file_id}[:@var{stream_specifier}]] | @var{[linklabel]} (@emph{output})
  647. Designate one or more input streams as a source for the output file. Each input
  648. stream is identified by the input file index @var{input_file_id} and
  649. the input stream index @var{input_stream_id} within the input
  650. file. Both indices start at 0. If specified,
  651. @var{sync_file_id}:@var{stream_specifier} sets which input stream
  652. is used as a presentation sync reference.
  653. The first @code{-map} option on the command line specifies the
  654. source for output stream 0, the second @code{-map} option specifies
  655. the source for output stream 1, etc.
  656. A @code{-} character before the stream identifier creates a "negative" mapping.
  657. It disables matching streams from already created mappings.
  658. An alternative @var{[linklabel]} form will map outputs from complex filter
  659. graphs (see the @option{-filter_complex} option) to the output file.
  660. @var{linklabel} must correspond to a defined output link label in the graph.
  661. For example, to map ALL streams from the first input file to output
  662. @example
  663. ffmpeg -i INPUT -map 0 output
  664. @end example
  665. For example, if you have two audio streams in the first input file,
  666. these streams are identified by "0:0" and "0:1". You can use
  667. @code{-map} to select which streams to place in an output file. For
  668. example:
  669. @example
  670. ffmpeg -i INPUT -map 0:1 out.wav
  671. @end example
  672. will map the input stream in @file{INPUT} identified by "0:1" to
  673. the (single) output stream in @file{out.wav}.
  674. For example, to select the stream with index 2 from input file
  675. @file{a.mov} (specified by the identifier "0:2"), and stream with
  676. index 6 from input @file{b.mov} (specified by the identifier "1:6"),
  677. and copy them to the output file @file{out.mov}:
  678. @example
  679. ffmpeg -i a.mov -i b.mov -c copy -map 0:2 -map 1:6 out.mov
  680. @end example
  681. To select all video and the third audio stream from an input file:
  682. @example
  683. ffmpeg -i INPUT -map 0:v -map 0:a:2 OUTPUT
  684. @end example
  685. To map all the streams except the second audio, use negative mappings
  686. @example
  687. ffmpeg -i INPUT -map 0 -map -0:a:1 OUTPUT
  688. @end example
  689. To pick the English audio stream:
  690. @example
  691. ffmpeg -i INPUT -map 0:m:language:eng OUTPUT
  692. @end example
  693. Note that using this option disables the default mappings for this output file.
  694. @item -ignore_unknown
  695. Ignore input streams with unknown type instead of failing if copying
  696. such streams is attempted.
  697. @item -copy_unknown
  698. Allow input streams with unknown type to be copied instead of failing if copying
  699. such streams is attempted.
  700. @item -map_channel [@var{input_file_id}.@var{stream_specifier}.@var{channel_id}|-1][:@var{output_file_id}.@var{stream_specifier}]
  701. Map an audio channel from a given input to an output. If
  702. @var{output_file_id}.@var{stream_specifier} is not set, the audio channel will
  703. be mapped on all the audio streams.
  704. Using "-1" instead of
  705. @var{input_file_id}.@var{stream_specifier}.@var{channel_id} will map a muted
  706. channel.
  707. For example, assuming @var{INPUT} is a stereo audio file, you can switch the
  708. two audio channels with the following command:
  709. @example
  710. ffmpeg -i INPUT -map_channel 0.0.1 -map_channel 0.0.0 OUTPUT
  711. @end example
  712. If you want to mute the first channel and keep the second:
  713. @example
  714. ffmpeg -i INPUT -map_channel -1 -map_channel 0.0.1 OUTPUT
  715. @end example
  716. The order of the "-map_channel" option specifies the order of the channels in
  717. the output stream. The output channel layout is guessed from the number of
  718. channels mapped (mono if one "-map_channel", stereo if two, etc.). Using "-ac"
  719. in combination of "-map_channel" makes the channel gain levels to be updated if
  720. input and output channel layouts don't match (for instance two "-map_channel"
  721. options and "-ac 6").
  722. You can also extract each channel of an input to specific outputs; the following
  723. command extracts two channels of the @var{INPUT} audio stream (file 0, stream 0)
  724. to the respective @var{OUTPUT_CH0} and @var{OUTPUT_CH1} outputs:
  725. @example
  726. ffmpeg -i INPUT -map_channel 0.0.0 OUTPUT_CH0 -map_channel 0.0.1 OUTPUT_CH1
  727. @end example
  728. The following example splits the channels of a stereo input into two separate
  729. streams, which are put into the same output file:
  730. @example
  731. ffmpeg -i stereo.wav -map 0:0 -map 0:0 -map_channel 0.0.0:0.0 -map_channel 0.0.1:0.1 -y out.ogg
  732. @end example
  733. Note that currently each output stream can only contain channels from a single
  734. input stream; you can't for example use "-map_channel" to pick multiple input
  735. audio channels contained in different streams (from the same or different files)
  736. and merge them into a single output stream. It is therefore not currently
  737. possible, for example, to turn two separate mono streams into a single stereo
  738. stream. However splitting a stereo stream into two single channel mono streams
  739. is possible.
  740. If you need this feature, a possible workaround is to use the @emph{amerge}
  741. filter. For example, if you need to merge a media (here @file{input.mkv}) with 2
  742. mono audio streams into one single stereo channel audio stream (and keep the
  743. video stream), you can use the following command:
  744. @example
  745. ffmpeg -i input.mkv -filter_complex "[0:1] [0:2] amerge" -c:a pcm_s16le -c:v copy output.mkv
  746. @end example
  747. @item -map_metadata[:@var{metadata_spec_out}] @var{infile}[:@var{metadata_spec_in}] (@emph{output,per-metadata})
  748. Set metadata information of the next output file from @var{infile}. Note that
  749. those are file indices (zero-based), not filenames.
  750. Optional @var{metadata_spec_in/out} parameters specify, which metadata to copy.
  751. A metadata specifier can have the following forms:
  752. @table @option
  753. @item @var{g}
  754. global metadata, i.e. metadata that applies to the whole file
  755. @item @var{s}[:@var{stream_spec}]
  756. per-stream metadata. @var{stream_spec} is a stream specifier as described
  757. in the @ref{Stream specifiers} chapter. In an input metadata specifier, the first
  758. matching stream is copied from. In an output metadata specifier, all matching
  759. streams are copied to.
  760. @item @var{c}:@var{chapter_index}
  761. per-chapter metadata. @var{chapter_index} is the zero-based chapter index.
  762. @item @var{p}:@var{program_index}
  763. per-program metadata. @var{program_index} is the zero-based program index.
  764. @end table
  765. If metadata specifier is omitted, it defaults to global.
  766. By default, global metadata is copied from the first input file,
  767. per-stream and per-chapter metadata is copied along with streams/chapters. These
  768. default mappings are disabled by creating any mapping of the relevant type. A negative
  769. file index can be used to create a dummy mapping that just disables automatic copying.
  770. For example to copy metadata from the first stream of the input file to global metadata
  771. of the output file:
  772. @example
  773. ffmpeg -i in.ogg -map_metadata 0:s:0 out.mp3
  774. @end example
  775. To do the reverse, i.e. copy global metadata to all audio streams:
  776. @example
  777. ffmpeg -i in.mkv -map_metadata:s:a 0:g out.mkv
  778. @end example
  779. Note that simple @code{0} would work as well in this example, since global
  780. metadata is assumed by default.
  781. @item -map_chapters @var{input_file_index} (@emph{output})
  782. Copy chapters from input file with index @var{input_file_index} to the next
  783. output file. If no chapter mapping is specified, then chapters are copied from
  784. the first input file with at least one chapter. Use a negative file index to
  785. disable any chapter copying.
  786. @item -benchmark (@emph{global})
  787. Show benchmarking information at the end of an encode.
  788. Shows CPU time used and maximum memory consumption.
  789. Maximum memory consumption is not supported on all systems,
  790. it will usually display as 0 if not supported.
  791. @item -benchmark_all (@emph{global})
  792. Show benchmarking information during the encode.
  793. Shows CPU time used in various steps (audio/video encode/decode).
  794. @item -timelimit @var{duration} (@emph{global})
  795. Exit after ffmpeg has been running for @var{duration} seconds.
  796. @item -dump (@emph{global})
  797. Dump each input packet to stderr.
  798. @item -hex (@emph{global})
  799. When dumping packets, also dump the payload.
  800. @item -re (@emph{input})
  801. Read input at native frame rate. Mainly used to simulate a grab device.
  802. or live input stream (e.g. when reading from a file). Should not be used
  803. with actual grab devices or live input streams (where it can cause packet
  804. loss).
  805. By default @command{ffmpeg} attempts to read the input(s) as fast as possible.
  806. This option will slow down the reading of the input(s) to the native frame rate
  807. of the input(s). It is useful for real-time output (e.g. live streaming).
  808. @item -loop_input
  809. Loop over the input stream. Currently it works only for image
  810. streams. This option is used for automatic FFserver testing.
  811. This option is deprecated, use -loop 1.
  812. @item -loop_output @var{number_of_times}
  813. Repeatedly loop output for formats that support looping such as animated GIF
  814. (0 will loop the output infinitely).
  815. This option is deprecated, use -loop.
  816. @item -vsync @var{parameter}
  817. Video sync method.
  818. For compatibility reasons old values can be specified as numbers.
  819. Newly added values will have to be specified as strings always.
  820. @table @option
  821. @item 0, passthrough
  822. Each frame is passed with its timestamp from the demuxer to the muxer.
  823. @item 1, cfr
  824. Frames will be duplicated and dropped to achieve exactly the requested
  825. constant frame rate.
  826. @item 2, vfr
  827. Frames are passed through with their timestamp or dropped so as to
  828. prevent 2 frames from having the same timestamp.
  829. @item drop
  830. As passthrough but destroys all timestamps, making the muxer generate
  831. fresh timestamps based on frame-rate.
  832. @item -1, auto
  833. Chooses between 1 and 2 depending on muxer capabilities. This is the
  834. default method.
  835. @end table
  836. Note that the timestamps may be further modified by the muxer, after this.
  837. For example, in the case that the format option @option{avoid_negative_ts}
  838. is enabled.
  839. With -map you can select from which stream the timestamps should be
  840. taken. You can leave either video or audio unchanged and sync the
  841. remaining stream(s) to the unchanged one.
  842. @item -frame_drop_threshold @var{parameter}
  843. Frame drop threshold, which specifies how much behind video frames can
  844. be before they are dropped. In frame rate units, so 1.0 is one frame.
  845. The default is -1.1. One possible usecase is to avoid framedrops in case
  846. of noisy timestamps or to increase frame drop precision in case of exact
  847. timestamps.
  848. @item -async @var{samples_per_second}
  849. Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
  850. the parameter is the maximum samples per second by which the audio is changed.
  851. -async 1 is a special case where only the start of the audio stream is corrected
  852. without any later correction.
  853. Note that the timestamps may be further modified by the muxer, after this.
  854. For example, in the case that the format option @option{avoid_negative_ts}
  855. is enabled.
  856. This option has been deprecated. Use the @code{aresample} audio filter instead.
  857. @item -copyts
  858. Do not process input timestamps, but keep their values without trying
  859. to sanitize them. In particular, do not remove the initial start time
  860. offset value.
  861. Note that, depending on the @option{vsync} option or on specific muxer
  862. processing (e.g. in case the format option @option{avoid_negative_ts}
  863. is enabled) the output timestamps may mismatch with the input
  864. timestamps even when this option is selected.
  865. @item -start_at_zero
  866. When used with @option{copyts}, shift input timestamps so they start at zero.
  867. This means that using e.g. @code{-ss 50} will make output timestamps start at
  868. 50 seconds, regardless of what timestamp the input file started at.
  869. @item -copytb @var{mode}
  870. Specify how to set the encoder timebase when stream copying. @var{mode} is an
  871. integer numeric value, and can assume one of the following values:
  872. @table @option
  873. @item 1
  874. Use the demuxer timebase.
  875. The time base is copied to the output encoder from the corresponding input
  876. demuxer. This is sometimes required to avoid non monotonically increasing
  877. timestamps when copying video streams with variable frame rate.
  878. @item 0
  879. Use the decoder timebase.
  880. The time base is copied to the output encoder from the corresponding input
  881. decoder.
  882. @item -1
  883. Try to make the choice automatically, in order to generate a sane output.
  884. @end table
  885. Default value is -1.
  886. @item -shortest (@emph{output})
  887. Finish encoding when the shortest input stream ends.
  888. @item -dts_delta_threshold
  889. Timestamp discontinuity delta threshold.
  890. @item -muxdelay @var{seconds} (@emph{input})
  891. Set the maximum demux-decode delay.
  892. @item -muxpreload @var{seconds} (@emph{input})
  893. Set the initial demux-decode delay.
  894. @item -streamid @var{output-stream-index}:@var{new-value} (@emph{output})
  895. Assign a new stream-id value to an output stream. This option should be
  896. specified prior to the output filename to which it applies.
  897. For the situation where multiple output files exist, a streamid
  898. may be reassigned to a different value.
  899. For example, to set the stream 0 PID to 33 and the stream 1 PID to 36 for
  900. an output mpegts file:
  901. @example
  902. ffmpeg -i infile -streamid 0:33 -streamid 1:36 out.ts
  903. @end example
  904. @item -bsf[:@var{stream_specifier}] @var{bitstream_filters} (@emph{output,per-stream})
  905. Set bitstream filters for matching streams. @var{bitstream_filters} is
  906. a comma-separated list of bitstream filters. Use the @code{-bsfs} option
  907. to get the list of bitstream filters.
  908. @example
  909. ffmpeg -i h264.mp4 -c:v copy -bsf:v h264_mp4toannexb -an out.h264
  910. @end example
  911. @example
  912. ffmpeg -i file.mov -an -vn -bsf:s mov2textsub -c:s copy -f rawvideo sub.txt
  913. @end example
  914. @item -tag[:@var{stream_specifier}] @var{codec_tag} (@emph{input/output,per-stream})
  915. Force a tag/fourcc for matching streams.
  916. @item -timecode @var{hh}:@var{mm}:@var{ss}SEP@var{ff}
  917. Specify Timecode for writing. @var{SEP} is ':' for non drop timecode and ';'
  918. (or '.') for drop.
  919. @example
  920. ffmpeg -i input.mpg -timecode 01:02:03.04 -r 30000/1001 -s ntsc output.mpg
  921. @end example
  922. @anchor{filter_complex_option}
  923. @item -filter_complex @var{filtergraph} (@emph{global})
  924. Define a complex filtergraph, i.e. one with arbitrary number of inputs and/or
  925. outputs. For simple graphs -- those with one input and one output of the same
  926. type -- see the @option{-filter} options. @var{filtergraph} is a description of
  927. the filtergraph, as described in the ``Filtergraph syntax'' section of the
  928. ffmpeg-filters manual.
  929. Input link labels must refer to input streams using the
  930. @code{[file_index:stream_specifier]} syntax (i.e. the same as @option{-map}
  931. uses). If @var{stream_specifier} matches multiple streams, the first one will be
  932. used. An unlabeled input will be connected to the first unused input stream of
  933. the matching type.
  934. Output link labels are referred to with @option{-map}. Unlabeled outputs are
  935. added to the first output file.
  936. Note that with this option it is possible to use only lavfi sources without
  937. normal input files.
  938. For example, to overlay an image over video
  939. @example
  940. ffmpeg -i video.mkv -i image.png -filter_complex '[0:v][1:v]overlay[out]' -map
  941. '[out]' out.mkv
  942. @end example
  943. Here @code{[0:v]} refers to the first video stream in the first input file,
  944. which is linked to the first (main) input of the overlay filter. Similarly the
  945. first video stream in the second input is linked to the second (overlay) input
  946. of overlay.
  947. Assuming there is only one video stream in each input file, we can omit input
  948. labels, so the above is equivalent to
  949. @example
  950. ffmpeg -i video.mkv -i image.png -filter_complex 'overlay[out]' -map
  951. '[out]' out.mkv
  952. @end example
  953. Furthermore we can omit the output label and the single output from the filter
  954. graph will be added to the output file automatically, so we can simply write
  955. @example
  956. ffmpeg -i video.mkv -i image.png -filter_complex 'overlay' out.mkv
  957. @end example
  958. To generate 5 seconds of pure red video using lavfi @code{color} source:
  959. @example
  960. ffmpeg -filter_complex 'color=c=red' -t 5 out.mkv
  961. @end example
  962. @item -lavfi @var{filtergraph} (@emph{global})
  963. Define a complex filtergraph, i.e. one with arbitrary number of inputs and/or
  964. outputs. Equivalent to @option{-filter_complex}.
  965. @item -filter_complex_script @var{filename} (@emph{global})
  966. This option is similar to @option{-filter_complex}, the only difference is that
  967. its argument is the name of the file from which a complex filtergraph
  968. description is to be read.
  969. @item -accurate_seek (@emph{input})
  970. This option enables or disables accurate seeking in input files with the
  971. @option{-ss} option. It is enabled by default, so seeking is accurate when
  972. transcoding. Use @option{-noaccurate_seek} to disable it, which may be useful
  973. e.g. when copying some streams and transcoding the others.
  974. @item -seek_timestamp (@emph{input})
  975. This option enables or disables seeking by timestamp in input files with the
  976. @option{-ss} option. It is disabled by default. If enabled, the argument
  977. to the @option{-ss} option is considered an actual timestamp, and is not
  978. offset by the start time of the file. This matters only for files which do
  979. not start from timestamp 0, such as transport streams.
  980. @item -thread_queue_size @var{size} (@emph{input})
  981. This option sets the maximum number of queued packets when reading from the
  982. file or device. With low latency / high rate live streams, packets may be
  983. discarded if they are not read in a timely manner; raising this value can
  984. avoid it.
  985. @item -override_ffserver (@emph{global})
  986. Overrides the input specifications from @command{ffserver}. Using this
  987. option you can map any input stream to @command{ffserver} and control
  988. many aspects of the encoding from @command{ffmpeg}. Without this
  989. option @command{ffmpeg} will transmit to @command{ffserver} what is
  990. requested by @command{ffserver}.
  991. The option is intended for cases where features are needed that cannot be
  992. specified to @command{ffserver} but can be to @command{ffmpeg}.
  993. @item -sdp_file @var{file} (@emph{global})
  994. Print sdp information to @var{file}.
  995. This allows dumping sdp information when at least one output isn't an
  996. rtp stream.
  997. @item -discard (@emph{input})
  998. Allows discarding specific streams or frames of streams at the demuxer.
  999. Not all demuxers support this.
  1000. @table @option
  1001. @item none
  1002. Discard no frame.
  1003. @item default
  1004. Default, which discards no frames.
  1005. @item noref
  1006. Discard all non-reference frames.
  1007. @item bidir
  1008. Discard all bidirectional frames.
  1009. @item nokey
  1010. Discard all frames excepts keyframes.
  1011. @item all
  1012. Discard all frames.
  1013. @end table
  1014. @item -abort_on @var{flags} (@emph{global})
  1015. Stop and abort on various conditions. The following flags are available:
  1016. @table @option
  1017. @item empty_output
  1018. No packets were passed to the muxer, the output is empty.
  1019. @end table
  1020. @item -xerror (@emph{global})
  1021. Stop and exit on error
  1022. @end table
  1023. As a special exception, you can use a bitmap subtitle stream as input: it
  1024. will be converted into a video with the same size as the largest video in
  1025. the file, or 720x576 if no video is present. Note that this is an
  1026. experimental and temporary solution. It will be removed once libavfilter has
  1027. proper support for subtitles.
  1028. For example, to hardcode subtitles on top of a DVB-T recording stored in
  1029. MPEG-TS format, delaying the subtitles by 1 second:
  1030. @example
  1031. ffmpeg -i input.ts -filter_complex \
  1032. '[#0x2ef] setpts=PTS+1/TB [sub] ; [#0x2d0] [sub] overlay' \
  1033. -sn -map '#0x2dc' output.mkv
  1034. @end example
  1035. (0x2d0, 0x2dc and 0x2ef are the MPEG-TS PIDs of respectively the video,
  1036. audio and subtitles streams; 0:0, 0:3 and 0:7 would have worked too)
  1037. @section Preset files
  1038. A preset file contains a sequence of @var{option}=@var{value} pairs,
  1039. one for each line, specifying a sequence of options which would be
  1040. awkward to specify on the command line. Lines starting with the hash
  1041. ('#') character are ignored and are used to provide comments. Check
  1042. the @file{presets} directory in the FFmpeg source tree for examples.
  1043. There are two types of preset files: ffpreset and avpreset files.
  1044. @subsection ffpreset files
  1045. ffpreset files are specified with the @code{vpre}, @code{apre},
  1046. @code{spre}, and @code{fpre} options. The @code{fpre} option takes the
  1047. filename of the preset instead of a preset name as input and can be
  1048. used for any kind of codec. For the @code{vpre}, @code{apre}, and
  1049. @code{spre} options, the options specified in a preset file are
  1050. applied to the currently selected codec of the same type as the preset
  1051. option.
  1052. The argument passed to the @code{vpre}, @code{apre}, and @code{spre}
  1053. preset options identifies the preset file to use according to the
  1054. following rules:
  1055. First ffmpeg searches for a file named @var{arg}.ffpreset in the
  1056. directories @file{$FFMPEG_DATADIR} (if set), and @file{$HOME/.ffmpeg}, and in
  1057. the datadir defined at configuration time (usually @file{PREFIX/share/ffmpeg})
  1058. or in a @file{ffpresets} folder along the executable on win32,
  1059. in that order. For example, if the argument is @code{libvpx-1080p}, it will
  1060. search for the file @file{libvpx-1080p.ffpreset}.
  1061. If no such file is found, then ffmpeg will search for a file named
  1062. @var{codec_name}-@var{arg}.ffpreset in the above-mentioned
  1063. directories, where @var{codec_name} is the name of the codec to which
  1064. the preset file options will be applied. For example, if you select
  1065. the video codec with @code{-vcodec libvpx} and use @code{-vpre 1080p},
  1066. then it will search for the file @file{libvpx-1080p.ffpreset}.
  1067. @subsection avpreset files
  1068. avpreset files are specified with the @code{pre} option. They work similar to
  1069. ffpreset files, but they only allow encoder- specific options. Therefore, an
  1070. @var{option}=@var{value} pair specifying an encoder cannot be used.
  1071. When the @code{pre} option is specified, ffmpeg will look for files with the
  1072. suffix .avpreset in the directories @file{$AVCONV_DATADIR} (if set), and
  1073. @file{$HOME/.avconv}, and in the datadir defined at configuration time (usually
  1074. @file{PREFIX/share/ffmpeg}), in that order.
  1075. First ffmpeg searches for a file named @var{codec_name}-@var{arg}.avpreset in
  1076. the above-mentioned directories, where @var{codec_name} is the name of the codec
  1077. to which the preset file options will be applied. For example, if you select the
  1078. video codec with @code{-vcodec libvpx} and use @code{-pre 1080p}, then it will
  1079. search for the file @file{libvpx-1080p.avpreset}.
  1080. If no such file is found, then ffmpeg will search for a file named
  1081. @var{arg}.avpreset in the same directories.
  1082. @c man end OPTIONS
  1083. @chapter Examples
  1084. @c man begin EXAMPLES
  1085. @section Video and Audio grabbing
  1086. If you specify the input format and device then ffmpeg can grab video
  1087. and audio directly.
  1088. @example
  1089. ffmpeg -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
  1090. @end example
  1091. Or with an ALSA audio source (mono input, card id 1) instead of OSS:
  1092. @example
  1093. ffmpeg -f alsa -ac 1 -i hw:1 -f video4linux2 -i /dev/video0 /tmp/out.mpg
  1094. @end example
  1095. Note that you must activate the right video source and channel before
  1096. launching ffmpeg with any TV viewer such as
  1097. @uref{http://linux.bytesex.org/xawtv/, xawtv} by Gerd Knorr. You also
  1098. have to set the audio recording levels correctly with a
  1099. standard mixer.
  1100. @section X11 grabbing
  1101. Grab the X11 display with ffmpeg via
  1102. @example
  1103. ffmpeg -f x11grab -video_size cif -framerate 25 -i :0.0 /tmp/out.mpg
  1104. @end example
  1105. 0.0 is display.screen number of your X11 server, same as
  1106. the DISPLAY environment variable.
  1107. @example
  1108. ffmpeg -f x11grab -video_size cif -framerate 25 -i :0.0+10,20 /tmp/out.mpg
  1109. @end example
  1110. 0.0 is display.screen number of your X11 server, same as the DISPLAY environment
  1111. variable. 10 is the x-offset and 20 the y-offset for the grabbing.
  1112. @section Video and Audio file format conversion
  1113. Any supported file format and protocol can serve as input to ffmpeg:
  1114. Examples:
  1115. @itemize
  1116. @item
  1117. You can use YUV files as input:
  1118. @example
  1119. ffmpeg -i /tmp/test%d.Y /tmp/out.mpg
  1120. @end example
  1121. It will use the files:
  1122. @example
  1123. /tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
  1124. /tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
  1125. @end example
  1126. The Y files use twice the resolution of the U and V files. They are
  1127. raw files, without header. They can be generated by all decent video
  1128. decoders. You must specify the size of the image with the @option{-s} option
  1129. if ffmpeg cannot guess it.
  1130. @item
  1131. You can input from a raw YUV420P file:
  1132. @example
  1133. ffmpeg -i /tmp/test.yuv /tmp/out.avi
  1134. @end example
  1135. test.yuv is a file containing raw YUV planar data. Each frame is composed
  1136. of the Y plane followed by the U and V planes at half vertical and
  1137. horizontal resolution.
  1138. @item
  1139. You can output to a raw YUV420P file:
  1140. @example
  1141. ffmpeg -i mydivx.avi hugefile.yuv
  1142. @end example
  1143. @item
  1144. You can set several input files and output files:
  1145. @example
  1146. ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
  1147. @end example
  1148. Converts the audio file a.wav and the raw YUV video file a.yuv
  1149. to MPEG file a.mpg.
  1150. @item
  1151. You can also do audio and video conversions at the same time:
  1152. @example
  1153. ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2
  1154. @end example
  1155. Converts a.wav to MPEG audio at 22050 Hz sample rate.
  1156. @item
  1157. You can encode to several formats at the same time and define a
  1158. mapping from input stream to output streams:
  1159. @example
  1160. ffmpeg -i /tmp/a.wav -map 0:a -b:a 64k /tmp/a.mp2 -map 0:a -b:a 128k /tmp/b.mp2
  1161. @end example
  1162. Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
  1163. file:index' specifies which input stream is used for each output
  1164. stream, in the order of the definition of output streams.
  1165. @item
  1166. You can transcode decrypted VOBs:
  1167. @example
  1168. ffmpeg -i snatch_1.vob -f avi -c:v mpeg4 -b:v 800k -g 300 -bf 2 -c:a libmp3lame -b:a 128k snatch.avi
  1169. @end example
  1170. This is a typical DVD ripping example; the input is a VOB file, the
  1171. output an AVI file with MPEG-4 video and MP3 audio. Note that in this
  1172. command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
  1173. GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
  1174. input video. Furthermore, the audio stream is MP3-encoded so you need
  1175. to enable LAME support by passing @code{--enable-libmp3lame} to configure.
  1176. The mapping is particularly useful for DVD transcoding
  1177. to get the desired audio language.
  1178. NOTE: To see the supported input formats, use @code{ffmpeg -formats}.
  1179. @item
  1180. You can extract images from a video, or create a video from many images:
  1181. For extracting images from a video:
  1182. @example
  1183. ffmpeg -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg
  1184. @end example
  1185. This will extract one video frame per second from the video and will
  1186. output them in files named @file{foo-001.jpeg}, @file{foo-002.jpeg},
  1187. etc. Images will be rescaled to fit the new WxH values.
  1188. If you want to extract just a limited number of frames, you can use the
  1189. above command in combination with the -vframes or -t option, or in
  1190. combination with -ss to start extracting from a certain point in time.
  1191. For creating a video from many images:
  1192. @example
  1193. ffmpeg -f image2 -framerate 12 -i foo-%03d.jpeg -s WxH foo.avi
  1194. @end example
  1195. The syntax @code{foo-%03d.jpeg} specifies to use a decimal number
  1196. composed of three digits padded with zeroes to express the sequence
  1197. number. It is the same syntax supported by the C printf function, but
  1198. only formats accepting a normal integer are suitable.
  1199. When importing an image sequence, -i also supports expanding
  1200. shell-like wildcard patterns (globbing) internally, by selecting the
  1201. image2-specific @code{-pattern_type glob} option.
  1202. For example, for creating a video from filenames matching the glob pattern
  1203. @code{foo-*.jpeg}:
  1204. @example
  1205. ffmpeg -f image2 -pattern_type glob -framerate 12 -i 'foo-*.jpeg' -s WxH foo.avi
  1206. @end example
  1207. @item
  1208. You can put many streams of the same type in the output:
  1209. @example
  1210. ffmpeg -i test1.avi -i test2.avi -map 1:1 -map 1:0 -map 0:1 -map 0:0 -c copy -y test12.nut
  1211. @end example
  1212. The resulting output file @file{test12.nut} will contain the first four streams
  1213. from the input files in reverse order.
  1214. @item
  1215. To force CBR video output:
  1216. @example
  1217. ffmpeg -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v
  1218. @end example
  1219. @item
  1220. The four options lmin, lmax, mblmin and mblmax use 'lambda' units,
  1221. but you may use the QP2LAMBDA constant to easily convert from 'q' units:
  1222. @example
  1223. ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext
  1224. @end example
  1225. @end itemize
  1226. @c man end EXAMPLES
  1227. @include config.texi
  1228. @ifset config-all
  1229. @ifset config-avutil
  1230. @include utils.texi
  1231. @end ifset
  1232. @ifset config-avcodec
  1233. @include codecs.texi
  1234. @include bitstream_filters.texi
  1235. @end ifset
  1236. @ifset config-avformat
  1237. @include formats.texi
  1238. @include protocols.texi
  1239. @end ifset
  1240. @ifset config-avdevice
  1241. @include devices.texi
  1242. @end ifset
  1243. @ifset config-swresample
  1244. @include resampler.texi
  1245. @end ifset
  1246. @ifset config-swscale
  1247. @include scaler.texi
  1248. @end ifset
  1249. @ifset config-avfilter
  1250. @include filters.texi
  1251. @end ifset
  1252. @end ifset
  1253. @chapter See Also
  1254. @ifhtml
  1255. @ifset config-all
  1256. @url{ffmpeg.html,ffmpeg}
  1257. @end ifset
  1258. @ifset config-not-all
  1259. @url{ffmpeg-all.html,ffmpeg-all},
  1260. @end ifset
  1261. @url{ffplay.html,ffplay}, @url{ffprobe.html,ffprobe}, @url{ffserver.html,ffserver},
  1262. @url{ffmpeg-utils.html,ffmpeg-utils},
  1263. @url{ffmpeg-scaler.html,ffmpeg-scaler},
  1264. @url{ffmpeg-resampler.html,ffmpeg-resampler},
  1265. @url{ffmpeg-codecs.html,ffmpeg-codecs},
  1266. @url{ffmpeg-bitstream-filters.html,ffmpeg-bitstream-filters},
  1267. @url{ffmpeg-formats.html,ffmpeg-formats},
  1268. @url{ffmpeg-devices.html,ffmpeg-devices},
  1269. @url{ffmpeg-protocols.html,ffmpeg-protocols},
  1270. @url{ffmpeg-filters.html,ffmpeg-filters}
  1271. @end ifhtml
  1272. @ifnothtml
  1273. @ifset config-all
  1274. ffmpeg(1),
  1275. @end ifset
  1276. @ifset config-not-all
  1277. ffmpeg-all(1),
  1278. @end ifset
  1279. ffplay(1), ffprobe(1), ffserver(1),
  1280. ffmpeg-utils(1), ffmpeg-scaler(1), ffmpeg-resampler(1),
  1281. ffmpeg-codecs(1), ffmpeg-bitstream-filters(1), ffmpeg-formats(1),
  1282. ffmpeg-devices(1), ffmpeg-protocols(1), ffmpeg-filters(1)
  1283. @end ifnothtml
  1284. @include authors.texi
  1285. @ignore
  1286. @setfilename ffmpeg
  1287. @settitle ffmpeg video converter
  1288. @end ignore
  1289. @bye