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  1. \input texinfo @c -*- texinfo -*-
  2. @settitle ffmpeg Documentation
  3. @titlepage
  4. @center @titlefont{ffmpeg Documentation}
  5. @end titlepage
  6. @top
  7. @contents
  8. @chapter Synopsis
  9. ffmpeg [@var{global_options}] @{[@var{input_file_options}] -i @file{input_file}@} ... @{[@var{output_file_options}] @file{output_file}@} ...
  10. @chapter Description
  11. @c man begin DESCRIPTION
  12. @command{ffmpeg} is a very fast video and audio converter that can also grab from
  13. a live audio/video source. It can also convert between arbitrary sample
  14. rates and resize video on the fly with a high quality polyphase filter.
  15. @command{ffmpeg} reads from an arbitrary number of input "files" (which can be regular
  16. files, pipes, network streams, grabbing devices, etc.), specified by the
  17. @code{-i} option, and writes to an arbitrary number of output "files", which are
  18. specified by a plain output filename. Anything found on the command line which
  19. cannot be interpreted as an option is considered to be an output filename.
  20. Each input or output file can, in principle, contain any number of streams of
  21. different types (video/audio/subtitle/attachment/data). The allowed number and/or
  22. types of streams may be limited by the container format. Selecting which
  23. streams from which inputs will go into which output is either done automatically
  24. or with the @code{-map} option (see the Stream selection chapter).
  25. To refer to input files in options, you must use their indices (0-based). E.g.
  26. the first input file is @code{0}, the second is @code{1}, etc. Similarly, streams
  27. within a file are referred to by their indices. E.g. @code{2:3} refers to the
  28. fourth stream in the third input file. Also see the Stream specifiers chapter.
  29. As a general rule, options are applied to the next specified
  30. file. Therefore, order is important, and you can have the same
  31. option on the command line multiple times. Each occurrence is
  32. then applied to the next input or output file.
  33. Exceptions from this rule are the global options (e.g. verbosity level),
  34. which should be specified first.
  35. Do not mix input and output files -- first specify all input files, then all
  36. output files. Also do not mix options which belong to different files. All
  37. options apply ONLY to the next input or output file and are reset between files.
  38. @itemize
  39. @item
  40. To set the video bitrate of the output file to 64 kbit/s:
  41. @example
  42. ffmpeg -i input.avi -b:v 64k -bufsize 64k output.avi
  43. @end example
  44. @item
  45. To force the frame rate of the output file to 24 fps:
  46. @example
  47. ffmpeg -i input.avi -r 24 output.avi
  48. @end example
  49. @item
  50. To force the frame rate of the input file (valid for raw formats only)
  51. to 1 fps and the frame rate of the output file to 24 fps:
  52. @example
  53. ffmpeg -r 1 -i input.m2v -r 24 output.avi
  54. @end example
  55. @end itemize
  56. The format option may be needed for raw input files.
  57. @c man end DESCRIPTION
  58. @chapter Detailed description
  59. @c man begin DETAILED DESCRIPTION
  60. The transcoding process in @command{ffmpeg} for each output can be described by
  61. the following diagram:
  62. @example
  63. _______ ______________
  64. | | | |
  65. | input | demuxer | encoded data | decoder
  66. | file | ---------> | packets | -----+
  67. |_______| |______________| |
  68. v
  69. _________
  70. | |
  71. | decoded |
  72. | frames |
  73. |_________|
  74. ________ ______________ |
  75. | | | | |
  76. | output | <-------- | encoded data | <----+
  77. | file | muxer | packets | encoder
  78. |________| |______________|
  79. @end example
  80. @command{ffmpeg} calls the libavformat library (containing demuxers) to read
  81. input files and get packets containing encoded data from them. When there are
  82. multiple input files, @command{ffmpeg} tries to keep them synchronized by
  83. tracking lowest timestamp on any active input stream.
  84. Encoded packets are then passed to the decoder (unless streamcopy is selected
  85. for the stream, see further for a description). The decoder produces
  86. uncompressed frames (raw video/PCM audio/...) which can be processed further by
  87. filtering (see next section). After filtering, the frames are passed to the
  88. encoder, which encodes them and outputs encoded packets. Finally those are
  89. passed to the muxer, which writes the encoded packets to the output file.
  90. @section Filtering
  91. Before encoding, @command{ffmpeg} can process raw audio and video frames using
  92. filters from the libavfilter library. Several chained filters form a filter
  93. graph. @command{ffmpeg} distinguishes between two types of filtergraphs:
  94. simple and complex.
  95. @subsection Simple filtergraphs
  96. Simple filtergraphs are those that have exactly one input and output, both of
  97. the same type. In the above diagram they can be represented by simply inserting
  98. an additional step between decoding and encoding:
  99. @example
  100. _________ ______________
  101. | | | |
  102. | decoded | | encoded data |
  103. | frames |\ _ | packets |
  104. |_________| \ /||______________|
  105. \ __________ /
  106. simple _\|| | / encoder
  107. filtergraph | filtered |/
  108. | frames |
  109. |__________|
  110. @end example
  111. Simple filtergraphs are configured with the per-stream @option{-filter} option
  112. (with @option{-vf} and @option{-af} aliases for video and audio respectively).
  113. A simple filtergraph for video can look for example like this:
  114. @example
  115. _______ _____________ _______ ________
  116. | | | | | | | |
  117. | input | ---> | deinterlace | ---> | scale | ---> | output |
  118. |_______| |_____________| |_______| |________|
  119. @end example
  120. Note that some filters change frame properties but not frame contents. E.g. the
  121. @code{fps} filter in the example above changes number of frames, but does not
  122. touch the frame contents. Another example is the @code{setpts} filter, which
  123. only sets timestamps and otherwise passes the frames unchanged.
  124. @subsection Complex filtergraphs
  125. Complex filtergraphs are those which cannot be described as simply a linear
  126. processing chain applied to one stream. This is the case, for example, when the graph has
  127. more than one input and/or output, or when output stream type is different from
  128. input. They can be represented with the following diagram:
  129. @example
  130. _________
  131. | |
  132. | input 0 |\ __________
  133. |_________| \ | |
  134. \ _________ /| output 0 |
  135. \ | | / |__________|
  136. _________ \| complex | /
  137. | | | |/
  138. | input 1 |---->| filter |\
  139. |_________| | | \ __________
  140. /| graph | \ | |
  141. / | | \| output 1 |
  142. _________ / |_________| |__________|
  143. | | /
  144. | input 2 |/
  145. |_________|
  146. @end example
  147. Complex filtergraphs are configured with the @option{-filter_complex} option.
  148. Note that this option is global, since a complex filtergraph, by its nature,
  149. cannot be unambiguously associated with a single stream or file.
  150. The @option{-lavfi} option is equivalent to @option{-filter_complex}.
  151. A trivial example of a complex filtergraph is the @code{overlay} filter, which
  152. has two video inputs and one video output, containing one video overlaid on top
  153. of the other. Its audio counterpart is the @code{amix} filter.
  154. @section Stream copy
  155. Stream copy is a mode selected by supplying the @code{copy} parameter to the
  156. @option{-codec} option. It makes @command{ffmpeg} omit the decoding and encoding
  157. step for the specified stream, so it does only demuxing and muxing. It is useful
  158. for changing the container format or modifying container-level metadata. The
  159. diagram above will, in this case, simplify to this:
  160. @example
  161. _______ ______________ ________
  162. | | | | | |
  163. | input | demuxer | encoded data | muxer | output |
  164. | file | ---------> | packets | -------> | file |
  165. |_______| |______________| |________|
  166. @end example
  167. Since there is no decoding or encoding, it is very fast and there is no quality
  168. loss. However, it might not work in some cases because of many factors. Applying
  169. filters is obviously also impossible, since filters work on uncompressed data.
  170. @c man end DETAILED DESCRIPTION
  171. @chapter Stream selection
  172. @c man begin STREAM SELECTION
  173. By default, @command{ffmpeg} includes only one stream of each type (video, audio, subtitle)
  174. present in the input files and adds them to each output file. It picks the
  175. "best" of each based upon the following criteria: for video, it is the stream
  176. with the highest resolution, for audio, it is the stream with the most channels, for
  177. subtitles, it is the first subtitle stream. In the case where several streams of
  178. the same type rate equally, the stream with the lowest index is chosen.
  179. You can disable some of those defaults by using the @code{-vn/-an/-sn} options. For
  180. full manual control, use the @code{-map} option, which disables the defaults just
  181. described.
  182. @c man end STREAM SELECTION
  183. @chapter Options
  184. @c man begin OPTIONS
  185. @include fftools-common-opts.texi
  186. @section Main options
  187. @table @option
  188. @item -f @var{fmt} (@emph{input/output})
  189. Force input or output file format. The format is normally auto detected for input
  190. files and guessed from the file extension for output files, so this option is not
  191. needed in most cases.
  192. @item -i @var{filename} (@emph{input})
  193. input file name
  194. @item -y (@emph{global})
  195. Overwrite output files without asking.
  196. @item -n (@emph{global})
  197. Do not overwrite output files, and exit immediately if a specified
  198. output file already exists.
  199. @item -c[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
  200. @itemx -codec[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
  201. Select an encoder (when used before an output file) or a decoder (when used
  202. before an input file) for one or more streams. @var{codec} is the name of a
  203. decoder/encoder or a special value @code{copy} (output only) to indicate that
  204. the stream is not to be re-encoded.
  205. For example
  206. @example
  207. ffmpeg -i INPUT -map 0 -c:v libx264 -c:a copy OUTPUT
  208. @end example
  209. encodes all video streams with libx264 and copies all audio streams.
  210. For each stream, the last matching @code{c} option is applied, so
  211. @example
  212. ffmpeg -i INPUT -map 0 -c copy -c:v:1 libx264 -c:a:137 libvorbis OUTPUT
  213. @end example
  214. will copy all the streams except the second video, which will be encoded with
  215. libx264, and the 138th audio, which will be encoded with libvorbis.
  216. @item -t @var{duration} (@emph{output})
  217. Stop writing the output after its duration reaches @var{duration}.
  218. @var{duration} may be a number in seconds, or in @code{hh:mm:ss[.xxx]} form.
  219. -to and -t are mutually exclusive and -t has priority.
  220. @item -to @var{position} (@emph{output})
  221. Stop writing the output at @var{position}.
  222. @var{position} may be a number in seconds, or in @code{hh:mm:ss[.xxx]} form.
  223. -to and -t are mutually exclusive and -t has priority.
  224. @item -fs @var{limit_size} (@emph{output})
  225. Set the file size limit, expressed in bytes.
  226. @item -ss @var{position} (@emph{input/output})
  227. When used as an input option (before @code{-i}), seeks in this input file to
  228. @var{position}. Note the in most formats it is not possible to seek exactly, so
  229. @command{ffmpeg} will seek to the closest seek point before @var{position}.
  230. When transcoding and @option{-accurate_seek} is enabled (the default), this
  231. extra segment between the seek point and @var{position} will be decoded and
  232. discarded. When doing stream copy or when @option{-noaccurate_seek} is used, it
  233. will be preserved.
  234. When used as an output option (before an output filename), decodes but discards
  235. input until the timestamps reach @var{position}.
  236. @var{position} may be either in seconds or in @code{hh:mm:ss[.xxx]} form.
  237. @item -itsoffset @var{offset} (@emph{input})
  238. Set the input time offset.
  239. @var{offset} must be a time duration specification,
  240. see @ref{time duration syntax,,the Time duration section in the ffmpeg-utils(1) manual,ffmpeg-utils}.
  241. The offset is added to the timestamps of the input files. Specifying
  242. a positive offset means that the corresponding streams are delayed by
  243. the time duration specified in @var{offset}.
  244. @item -timestamp @var{date} (@emph{output})
  245. Set the recording timestamp in the container.
  246. @var{date} must be a time duration specification,
  247. see @ref{date syntax,,the Date section in the ffmpeg-utils(1) manual,ffmpeg-utils}.
  248. @item -metadata[:metadata_specifier] @var{key}=@var{value} (@emph{output,per-metadata})
  249. Set a metadata key/value pair.
  250. An optional @var{metadata_specifier} may be given to set metadata
  251. on streams or chapters. See @code{-map_metadata} documentation for
  252. details.
  253. This option overrides metadata set with @code{-map_metadata}. It is
  254. also possible to delete metadata by using an empty value.
  255. For example, for setting the title in the output file:
  256. @example
  257. ffmpeg -i in.avi -metadata title="my title" out.flv
  258. @end example
  259. To set the language of the first audio stream:
  260. @example
  261. ffmpeg -i INPUT -metadata:s:a:1 language=eng OUTPUT
  262. @end example
  263. @item -target @var{type} (@emph{output})
  264. Specify target file type (@code{vcd}, @code{svcd}, @code{dvd}, @code{dv},
  265. @code{dv50}). @var{type} may be prefixed with @code{pal-}, @code{ntsc-} or
  266. @code{film-} to use the corresponding standard. All the format options
  267. (bitrate, codecs, buffer sizes) are then set automatically. You can just type:
  268. @example
  269. ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg
  270. @end example
  271. Nevertheless you can specify additional options as long as you know
  272. they do not conflict with the standard, as in:
  273. @example
  274. ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
  275. @end example
  276. @item -dframes @var{number} (@emph{output})
  277. Set the number of data frames to record. This is an alias for @code{-frames:d}.
  278. @item -frames[:@var{stream_specifier}] @var{framecount} (@emph{output,per-stream})
  279. Stop writing to the stream after @var{framecount} frames.
  280. @item -q[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
  281. @itemx -qscale[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
  282. Use fixed quality scale (VBR). The meaning of @var{q}/@var{qscale} is
  283. codec-dependent.
  284. If @var{qscale} is used without a @var{stream_specifier} then it applies only
  285. to the video stream, this is to maintain compatibility with previous behavior
  286. and as specifying the same codec specific value to 2 different codecs that is
  287. audio and video generally is not what is intended when no stream_specifier is
  288. used.
  289. @anchor{filter_option}
  290. @item -filter[:@var{stream_specifier}] @var{filtergraph} (@emph{output,per-stream})
  291. Create the filtergraph specified by @var{filtergraph} and use it to
  292. filter the stream.
  293. @var{filtergraph} is a description of the filtergraph to apply to
  294. the stream, and must have a single input and a single output of the
  295. same type of the stream. In the filtergraph, the input is associated
  296. to the label @code{in}, and the output to the label @code{out}. See
  297. the ffmpeg-filters manual for more information about the filtergraph
  298. syntax.
  299. See the @ref{filter_complex_option,,-filter_complex option} if you
  300. want to create filtergraphs with multiple inputs and/or outputs.
  301. @item -filter_script[:@var{stream_specifier}] @var{filename} (@emph{output,per-stream})
  302. This option is similar to @option{-filter}, the only difference is that its
  303. argument is the name of the file from which a filtergraph description is to be
  304. read.
  305. @item -pre[:@var{stream_specifier}] @var{preset_name} (@emph{output,per-stream})
  306. Specify the preset for matching stream(s).
  307. @item -stats (@emph{global})
  308. Print encoding progress/statistics. It is on by default, to explicitly
  309. disable it you need to specify @code{-nostats}.
  310. @item -progress @var{url} (@emph{global})
  311. Send program-friendly progress information to @var{url}.
  312. Progress information is written approximately every second and at the end of
  313. the encoding process. It is made of "@var{key}=@var{value}" lines. @var{key}
  314. consists of only alphanumeric characters. The last key of a sequence of
  315. progress information is always "progress".
  316. @item -stdin
  317. Enable interaction on standard input. On by default unless standard input is
  318. used as an input. To explicitly disable interaction you need to specify
  319. @code{-nostdin}.
  320. Disabling interaction on standard input is useful, for example, if
  321. ffmpeg is in the background process group. Roughly the same result can
  322. be achieved with @code{ffmpeg ... < /dev/null} but it requires a
  323. shell.
  324. @item -debug_ts (@emph{global})
  325. Print timestamp information. It is off by default. This option is
  326. mostly useful for testing and debugging purposes, and the output
  327. format may change from one version to another, so it should not be
  328. employed by portable scripts.
  329. See also the option @code{-fdebug ts}.
  330. @item -attach @var{filename} (@emph{output})
  331. Add an attachment to the output file. This is supported by a few formats
  332. like Matroska for e.g. fonts used in rendering subtitles. Attachments
  333. are implemented as a specific type of stream, so this option will add
  334. a new stream to the file. It is then possible to use per-stream options
  335. on this stream in the usual way. Attachment streams created with this
  336. option will be created after all the other streams (i.e. those created
  337. with @code{-map} or automatic mappings).
  338. Note that for Matroska you also have to set the mimetype metadata tag:
  339. @example
  340. ffmpeg -i INPUT -attach DejaVuSans.ttf -metadata:s:2 mimetype=application/x-truetype-font out.mkv
  341. @end example
  342. (assuming that the attachment stream will be third in the output file).
  343. @item -dump_attachment[:@var{stream_specifier}] @var{filename} (@emph{input,per-stream})
  344. Extract the matching attachment stream into a file named @var{filename}. If
  345. @var{filename} is empty, then the value of the @code{filename} metadata tag
  346. will be used.
  347. E.g. to extract the first attachment to a file named 'out.ttf':
  348. @example
  349. ffmpeg -dump_attachment:t:0 out.ttf -i INPUT
  350. @end example
  351. To extract all attachments to files determined by the @code{filename} tag:
  352. @example
  353. ffmpeg -dump_attachment:t "" -i INPUT
  354. @end example
  355. Technical note -- attachments are implemented as codec extradata, so this
  356. option can actually be used to extract extradata from any stream, not just
  357. attachments.
  358. @end table
  359. @section Video Options
  360. @table @option
  361. @item -vframes @var{number} (@emph{output})
  362. Set the number of video frames to record. This is an alias for @code{-frames:v}.
  363. @item -r[:@var{stream_specifier}] @var{fps} (@emph{input/output,per-stream})
  364. Set frame rate (Hz value, fraction or abbreviation).
  365. As an input option, ignore any timestamps stored in the file and instead
  366. generate timestamps assuming constant frame rate @var{fps}.
  367. As an output option, duplicate or drop input frames to achieve constant output
  368. frame rate @var{fps}.
  369. @item -s[:@var{stream_specifier}] @var{size} (@emph{input/output,per-stream})
  370. Set frame size.
  371. As an input option, this is a shortcut for the @option{video_size} private
  372. option, recognized by some demuxers for which the frame size is either not
  373. stored in the file or is configurable -- e.g. raw video or video grabbers.
  374. As an output option, this inserts the @code{scale} video filter to the
  375. @emph{end} of the corresponding filtergraph. Please use the @code{scale} filter
  376. directly to insert it at the beginning or some other place.
  377. The format is @samp{wxh} (default - same as source).
  378. @item -aspect[:@var{stream_specifier}] @var{aspect} (@emph{output,per-stream})
  379. Set the video display aspect ratio specified by @var{aspect}.
  380. @var{aspect} can be a floating point number string, or a string of the
  381. form @var{num}:@var{den}, where @var{num} and @var{den} are the
  382. numerator and denominator of the aspect ratio. For example "4:3",
  383. "16:9", "1.3333", and "1.7777" are valid argument values.
  384. If used together with @option{-vcodec copy}, it will affect the aspect ratio
  385. stored at container level, but not the aspect ratio stored in encoded
  386. frames, if it exists.
  387. @item -vn (@emph{output})
  388. Disable video recording.
  389. @item -vcodec @var{codec} (@emph{output})
  390. Set the video codec. This is an alias for @code{-codec:v}.
  391. @item -pass[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
  392. Select the pass number (1 or 2). It is used to do two-pass
  393. video encoding. The statistics of the video are recorded in the first
  394. pass into a log file (see also the option -passlogfile),
  395. and in the second pass that log file is used to generate the video
  396. at the exact requested bitrate.
  397. On pass 1, you may just deactivate audio and set output to null,
  398. examples for Windows and Unix:
  399. @example
  400. ffmpeg -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y NUL
  401. ffmpeg -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null
  402. @end example
  403. @item -passlogfile[:@var{stream_specifier}] @var{prefix} (@emph{output,per-stream})
  404. Set two-pass log file name prefix to @var{prefix}, the default file name
  405. prefix is ``ffmpeg2pass''. The complete file name will be
  406. @file{PREFIX-N.log}, where N is a number specific to the output
  407. stream
  408. @item -vf @var{filtergraph} (@emph{output})
  409. Create the filtergraph specified by @var{filtergraph} and use it to
  410. filter the stream.
  411. This is an alias for @code{-filter:v}, see the @ref{filter_option,,-filter option}.
  412. @end table
  413. @section Advanced Video Options
  414. @table @option
  415. @item -pix_fmt[:@var{stream_specifier}] @var{format} (@emph{input/output,per-stream})
  416. Set pixel format. Use @code{-pix_fmts} to show all the supported
  417. pixel formats.
  418. If the selected pixel format can not be selected, ffmpeg will print a
  419. warning and select the best pixel format supported by the encoder.
  420. If @var{pix_fmt} is prefixed by a @code{+}, ffmpeg will exit with an error
  421. if the requested pixel format can not be selected, and automatic conversions
  422. inside filtergraphs are disabled.
  423. If @var{pix_fmt} is a single @code{+}, ffmpeg selects the same pixel format
  424. as the input (or graph output) and automatic conversions are disabled.
  425. @item -sws_flags @var{flags} (@emph{input/output})
  426. Set SwScaler flags.
  427. @item -vdt @var{n}
  428. Discard threshold.
  429. @item -rc_override[:@var{stream_specifier}] @var{override} (@emph{output,per-stream})
  430. Rate control override for specific intervals, formatted as "int,int,int"
  431. list separated with slashes. Two first values are the beginning and
  432. end frame numbers, last one is quantizer to use if positive, or quality
  433. factor if negative.
  434. @item -ilme
  435. Force interlacing support in encoder (MPEG-2 and MPEG-4 only).
  436. Use this option if your input file is interlaced and you want
  437. to keep the interlaced format for minimum losses.
  438. The alternative is to deinterlace the input stream with
  439. @option{-deinterlace}, but deinterlacing introduces losses.
  440. @item -psnr
  441. Calculate PSNR of compressed frames.
  442. @item -vstats
  443. Dump video coding statistics to @file{vstats_HHMMSS.log}.
  444. @item -vstats_file @var{file}
  445. Dump video coding statistics to @var{file}.
  446. @item -top[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
  447. top=1/bottom=0/auto=-1 field first
  448. @item -dc @var{precision}
  449. Intra_dc_precision.
  450. @item -vtag @var{fourcc/tag} (@emph{output})
  451. Force video tag/fourcc. This is an alias for @code{-tag:v}.
  452. @item -qphist (@emph{global})
  453. Show QP histogram
  454. @item -vbsf @var{bitstream_filter}
  455. Deprecated see -bsf
  456. @item -force_key_frames[:@var{stream_specifier}] @var{time}[,@var{time}...] (@emph{output,per-stream})
  457. @item -force_key_frames[:@var{stream_specifier}] expr:@var{expr} (@emph{output,per-stream})
  458. Force key frames at the specified timestamps, more precisely at the first
  459. frames after each specified time.
  460. If the argument is prefixed with @code{expr:}, the string @var{expr}
  461. is interpreted like an expression and is evaluated for each frame. A
  462. key frame is forced in case the evaluation is non-zero.
  463. If one of the times is "@code{chapters}[@var{delta}]", it is expanded into
  464. the time of the beginning of all chapters in the file, shifted by
  465. @var{delta}, expressed as a time in seconds.
  466. This option can be useful to ensure that a seek point is present at a
  467. chapter mark or any other designated place in the output file.
  468. For example, to insert a key frame at 5 minutes, plus key frames 0.1 second
  469. before the beginning of every chapter:
  470. @example
  471. -force_key_frames 0:05:00,chapters-0.1
  472. @end example
  473. The expression in @var{expr} can contain the following constants:
  474. @table @option
  475. @item n
  476. the number of current processed frame, starting from 0
  477. @item n_forced
  478. the number of forced frames
  479. @item prev_forced_n
  480. the number of the previous forced frame, it is @code{NAN} when no
  481. keyframe was forced yet
  482. @item prev_forced_t
  483. the time of the previous forced frame, it is @code{NAN} when no
  484. keyframe was forced yet
  485. @item t
  486. the time of the current processed frame
  487. @end table
  488. For example to force a key frame every 5 seconds, you can specify:
  489. @example
  490. -force_key_frames expr:gte(t,n_forced*5)
  491. @end example
  492. To force a key frame 5 seconds after the time of the last forced one,
  493. starting from second 13:
  494. @example
  495. -force_key_frames expr:if(isnan(prev_forced_t),gte(t,13),gte(t,prev_forced_t+5))
  496. @end example
  497. Note that forcing too many keyframes is very harmful for the lookahead
  498. algorithms of certain encoders: using fixed-GOP options or similar
  499. would be more efficient.
  500. @item -copyinkf[:@var{stream_specifier}] (@emph{output,per-stream})
  501. When doing stream copy, copy also non-key frames found at the
  502. beginning.
  503. @item -hwaccel[:@var{stream_specifier}] @var{hwaccel} (@emph{input,per-stream})
  504. Use hardware acceleration to decode the matching stream(s). The allowed values
  505. of @var{hwaccel} are:
  506. @table @option
  507. @item none
  508. Do not use any hardware acceleration (the default).
  509. @item auto
  510. Automatically select the hardware acceleration method.
  511. @item vdpau
  512. Use VDPAU (Video Decode and Presentation API for Unix) hardware acceleration.
  513. @item dxva2
  514. Use DXVA2 (DirectX Video Acceleration) hardware acceleration.
  515. @end table
  516. This option has no effect if the selected hwaccel is not available or not
  517. supported by the chosen decoder.
  518. Note that most acceleration methods are intended for playback and will not be
  519. faster than software decoding on modern CPUs. Additionally, @command{ffmpeg}
  520. will usually need to copy the decoded frames from the GPU memory into the system
  521. memory, resulting in further performance loss. This option is thus mainly
  522. useful for testing.
  523. @item -hwaccel_device[:@var{stream_specifier}] @var{hwaccel_device} (@emph{input,per-stream})
  524. Select a device to use for hardware acceleration.
  525. This option only makes sense when the @option{-hwaccel} option is also
  526. specified. Its exact meaning depends on the specific hardware acceleration
  527. method chosen.
  528. @table @option
  529. @item vdpau
  530. For VDPAU, this option specifies the X11 display/screen to use. If this option
  531. is not specified, the value of the @var{DISPLAY} environment variable is used
  532. @item dxva2
  533. For DXVA2, this option should contain the number of the display adapter to use.
  534. If this option is not specified, the default adapter is used.
  535. @end table
  536. @end table
  537. @section Audio Options
  538. @table @option
  539. @item -aframes @var{number} (@emph{output})
  540. Set the number of audio frames to record. This is an alias for @code{-frames:a}.
  541. @item -ar[:@var{stream_specifier}] @var{freq} (@emph{input/output,per-stream})
  542. Set the audio sampling frequency. For output streams it is set by
  543. default to the frequency of the corresponding input stream. For input
  544. streams this option only makes sense for audio grabbing devices and raw
  545. demuxers and is mapped to the corresponding demuxer options.
  546. @item -aq @var{q} (@emph{output})
  547. Set the audio quality (codec-specific, VBR). This is an alias for -q:a.
  548. @item -ac[:@var{stream_specifier}] @var{channels} (@emph{input/output,per-stream})
  549. Set the number of audio channels. For output streams it is set by
  550. default to the number of input audio channels. For input streams
  551. this option only makes sense for audio grabbing devices and raw demuxers
  552. and is mapped to the corresponding demuxer options.
  553. @item -an (@emph{output})
  554. Disable audio recording.
  555. @item -acodec @var{codec} (@emph{input/output})
  556. Set the audio codec. This is an alias for @code{-codec:a}.
  557. @item -sample_fmt[:@var{stream_specifier}] @var{sample_fmt} (@emph{output,per-stream})
  558. Set the audio sample format. Use @code{-sample_fmts} to get a list
  559. of supported sample formats.
  560. @item -af @var{filtergraph} (@emph{output})
  561. Create the filtergraph specified by @var{filtergraph} and use it to
  562. filter the stream.
  563. This is an alias for @code{-filter:a}, see the @ref{filter_option,,-filter option}.
  564. @end table
  565. @section Advanced Audio options:
  566. @table @option
  567. @item -atag @var{fourcc/tag} (@emph{output})
  568. Force audio tag/fourcc. This is an alias for @code{-tag:a}.
  569. @item -absf @var{bitstream_filter}
  570. Deprecated, see -bsf
  571. @item -guess_layout_max @var{channels} (@emph{input,per-stream})
  572. If some input channel layout is not known, try to guess only if it
  573. corresponds to at most the specified number of channels. For example, 2
  574. tells to @command{ffmpeg} to recognize 1 channel as mono and 2 channels as
  575. stereo but not 6 channels as 5.1. The default is to always try to guess. Use
  576. 0 to disable all guessing.
  577. @end table
  578. @section Subtitle options:
  579. @table @option
  580. @item -scodec @var{codec} (@emph{input/output})
  581. Set the subtitle codec. This is an alias for @code{-codec:s}.
  582. @item -sn (@emph{output})
  583. Disable subtitle recording.
  584. @item -sbsf @var{bitstream_filter}
  585. Deprecated, see -bsf
  586. @end table
  587. @section Advanced Subtitle options:
  588. @table @option
  589. @item -fix_sub_duration
  590. Fix subtitles durations. For each subtitle, wait for the next packet in the
  591. same stream and adjust the duration of the first to avoid overlap. This is
  592. necessary with some subtitles codecs, especially DVB subtitles, because the
  593. duration in the original packet is only a rough estimate and the end is
  594. actually marked by an empty subtitle frame. Failing to use this option when
  595. necessary can result in exaggerated durations or muxing failures due to
  596. non-monotonic timestamps.
  597. Note that this option will delay the output of all data until the next
  598. subtitle packet is decoded: it may increase memory consumption and latency a
  599. lot.
  600. @item -canvas_size @var{size}
  601. Set the size of the canvas used to render subtitles.
  602. @end table
  603. @section Advanced options
  604. @table @option
  605. @item -map [-]@var{input_file_id}[:@var{stream_specifier}][,@var{sync_file_id}[:@var{stream_specifier}]] | @var{[linklabel]} (@emph{output})
  606. Designate one or more input streams as a source for the output file. Each input
  607. stream is identified by the input file index @var{input_file_id} and
  608. the input stream index @var{input_stream_id} within the input
  609. file. Both indices start at 0. If specified,
  610. @var{sync_file_id}:@var{stream_specifier} sets which input stream
  611. is used as a presentation sync reference.
  612. The first @code{-map} option on the command line specifies the
  613. source for output stream 0, the second @code{-map} option specifies
  614. the source for output stream 1, etc.
  615. A @code{-} character before the stream identifier creates a "negative" mapping.
  616. It disables matching streams from already created mappings.
  617. An alternative @var{[linklabel]} form will map outputs from complex filter
  618. graphs (see the @option{-filter_complex} option) to the output file.
  619. @var{linklabel} must correspond to a defined output link label in the graph.
  620. For example, to map ALL streams from the first input file to output
  621. @example
  622. ffmpeg -i INPUT -map 0 output
  623. @end example
  624. For example, if you have two audio streams in the first input file,
  625. these streams are identified by "0:0" and "0:1". You can use
  626. @code{-map} to select which streams to place in an output file. For
  627. example:
  628. @example
  629. ffmpeg -i INPUT -map 0:1 out.wav
  630. @end example
  631. will map the input stream in @file{INPUT} identified by "0:1" to
  632. the (single) output stream in @file{out.wav}.
  633. For example, to select the stream with index 2 from input file
  634. @file{a.mov} (specified by the identifier "0:2"), and stream with
  635. index 6 from input @file{b.mov} (specified by the identifier "1:6"),
  636. and copy them to the output file @file{out.mov}:
  637. @example
  638. ffmpeg -i a.mov -i b.mov -c copy -map 0:2 -map 1:6 out.mov
  639. @end example
  640. To select all video and the third audio stream from an input file:
  641. @example
  642. ffmpeg -i INPUT -map 0:v -map 0:a:2 OUTPUT
  643. @end example
  644. To map all the streams except the second audio, use negative mappings
  645. @example
  646. ffmpeg -i INPUT -map 0 -map -0:a:1 OUTPUT
  647. @end example
  648. Note that using this option disables the default mappings for this output file.
  649. @item -map_channel [@var{input_file_id}.@var{stream_specifier}.@var{channel_id}|-1][:@var{output_file_id}.@var{stream_specifier}]
  650. Map an audio channel from a given input to an output. If
  651. @var{output_file_id}.@var{stream_specifier} is not set, the audio channel will
  652. be mapped on all the audio streams.
  653. Using "-1" instead of
  654. @var{input_file_id}.@var{stream_specifier}.@var{channel_id} will map a muted
  655. channel.
  656. For example, assuming @var{INPUT} is a stereo audio file, you can switch the
  657. two audio channels with the following command:
  658. @example
  659. ffmpeg -i INPUT -map_channel 0.0.1 -map_channel 0.0.0 OUTPUT
  660. @end example
  661. If you want to mute the first channel and keep the second:
  662. @example
  663. ffmpeg -i INPUT -map_channel -1 -map_channel 0.0.1 OUTPUT
  664. @end example
  665. The order of the "-map_channel" option specifies the order of the channels in
  666. the output stream. The output channel layout is guessed from the number of
  667. channels mapped (mono if one "-map_channel", stereo if two, etc.). Using "-ac"
  668. in combination of "-map_channel" makes the channel gain levels to be updated if
  669. input and output channel layouts don't match (for instance two "-map_channel"
  670. options and "-ac 6").
  671. You can also extract each channel of an input to specific outputs; the following
  672. command extracts two channels of the @var{INPUT} audio stream (file 0, stream 0)
  673. to the respective @var{OUTPUT_CH0} and @var{OUTPUT_CH1} outputs:
  674. @example
  675. ffmpeg -i INPUT -map_channel 0.0.0 OUTPUT_CH0 -map_channel 0.0.1 OUTPUT_CH1
  676. @end example
  677. The following example splits the channels of a stereo input into two separate
  678. streams, which are put into the same output file:
  679. @example
  680. 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
  681. @end example
  682. Note that currently each output stream can only contain channels from a single
  683. input stream; you can't for example use "-map_channel" to pick multiple input
  684. audio channels contained in different streams (from the same or different files)
  685. and merge them into a single output stream. It is therefore not currently
  686. possible, for example, to turn two separate mono streams into a single stereo
  687. stream. However splitting a stereo stream into two single channel mono streams
  688. is possible.
  689. If you need this feature, a possible workaround is to use the @emph{amerge}
  690. filter. For example, if you need to merge a media (here @file{input.mkv}) with 2
  691. mono audio streams into one single stereo channel audio stream (and keep the
  692. video stream), you can use the following command:
  693. @example
  694. ffmpeg -i input.mkv -filter_complex "[0:1] [0:2] amerge" -c:a pcm_s16le -c:v copy output.mkv
  695. @end example
  696. @item -map_metadata[:@var{metadata_spec_out}] @var{infile}[:@var{metadata_spec_in}] (@emph{output,per-metadata})
  697. Set metadata information of the next output file from @var{infile}. Note that
  698. those are file indices (zero-based), not filenames.
  699. Optional @var{metadata_spec_in/out} parameters specify, which metadata to copy.
  700. A metadata specifier can have the following forms:
  701. @table @option
  702. @item @var{g}
  703. global metadata, i.e. metadata that applies to the whole file
  704. @item @var{s}[:@var{stream_spec}]
  705. per-stream metadata. @var{stream_spec} is a stream specifier as described
  706. in the @ref{Stream specifiers} chapter. In an input metadata specifier, the first
  707. matching stream is copied from. In an output metadata specifier, all matching
  708. streams are copied to.
  709. @item @var{c}:@var{chapter_index}
  710. per-chapter metadata. @var{chapter_index} is the zero-based chapter index.
  711. @item @var{p}:@var{program_index}
  712. per-program metadata. @var{program_index} is the zero-based program index.
  713. @end table
  714. If metadata specifier is omitted, it defaults to global.
  715. By default, global metadata is copied from the first input file,
  716. per-stream and per-chapter metadata is copied along with streams/chapters. These
  717. default mappings are disabled by creating any mapping of the relevant type. A negative
  718. file index can be used to create a dummy mapping that just disables automatic copying.
  719. For example to copy metadata from the first stream of the input file to global metadata
  720. of the output file:
  721. @example
  722. ffmpeg -i in.ogg -map_metadata 0:s:0 out.mp3
  723. @end example
  724. To do the reverse, i.e. copy global metadata to all audio streams:
  725. @example
  726. ffmpeg -i in.mkv -map_metadata:s:a 0:g out.mkv
  727. @end example
  728. Note that simple @code{0} would work as well in this example, since global
  729. metadata is assumed by default.
  730. @item -map_chapters @var{input_file_index} (@emph{output})
  731. Copy chapters from input file with index @var{input_file_index} to the next
  732. output file. If no chapter mapping is specified, then chapters are copied from
  733. the first input file with at least one chapter. Use a negative file index to
  734. disable any chapter copying.
  735. @item -benchmark (@emph{global})
  736. Show benchmarking information at the end of an encode.
  737. Shows CPU time used and maximum memory consumption.
  738. Maximum memory consumption is not supported on all systems,
  739. it will usually display as 0 if not supported.
  740. @item -benchmark_all (@emph{global})
  741. Show benchmarking information during the encode.
  742. Shows CPU time used in various steps (audio/video encode/decode).
  743. @item -timelimit @var{duration} (@emph{global})
  744. Exit after ffmpeg has been running for @var{duration} seconds.
  745. @item -dump (@emph{global})
  746. Dump each input packet to stderr.
  747. @item -hex (@emph{global})
  748. When dumping packets, also dump the payload.
  749. @item -re (@emph{input})
  750. Read input at native frame rate. Mainly used to simulate a grab device.
  751. or live input stream (e.g. when reading from a file). Should not be used
  752. with actual grab devices or live input streams (where it can cause packet
  753. loss).
  754. By default @command{ffmpeg} attempts to read the input(s) as fast as possible.
  755. This option will slow down the reading of the input(s) to the native frame rate
  756. of the input(s). It is useful for real-time output (e.g. live streaming).
  757. @item -loop_input
  758. Loop over the input stream. Currently it works only for image
  759. streams. This option is used for automatic FFserver testing.
  760. This option is deprecated, use -loop 1.
  761. @item -loop_output @var{number_of_times}
  762. Repeatedly loop output for formats that support looping such as animated GIF
  763. (0 will loop the output infinitely).
  764. This option is deprecated, use -loop.
  765. @item -vsync @var{parameter}
  766. Video sync method.
  767. For compatibility reasons old values can be specified as numbers.
  768. Newly added values will have to be specified as strings always.
  769. @table @option
  770. @item 0, passthrough
  771. Each frame is passed with its timestamp from the demuxer to the muxer.
  772. @item 1, cfr
  773. Frames will be duplicated and dropped to achieve exactly the requested
  774. constant frame rate.
  775. @item 2, vfr
  776. Frames are passed through with their timestamp or dropped so as to
  777. prevent 2 frames from having the same timestamp.
  778. @item drop
  779. As passthrough but destroys all timestamps, making the muxer generate
  780. fresh timestamps based on frame-rate.
  781. @item -1, auto
  782. Chooses between 1 and 2 depending on muxer capabilities. This is the
  783. default method.
  784. @end table
  785. Note that the timestamps may be further modified by the muxer, after this.
  786. For example, in the case that the format option @option{avoid_negative_ts}
  787. is enabled.
  788. With -map you can select from which stream the timestamps should be
  789. taken. You can leave either video or audio unchanged and sync the
  790. remaining stream(s) to the unchanged one.
  791. @item -async @var{samples_per_second}
  792. Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
  793. the parameter is the maximum samples per second by which the audio is changed.
  794. -async 1 is a special case where only the start of the audio stream is corrected
  795. without any later correction.
  796. Note that the timestamps may be further modified by the muxer, after this.
  797. For example, in the case that the format option @option{avoid_negative_ts}
  798. is enabled.
  799. This option has been deprecated. Use the @code{aresample} audio filter instead.
  800. @item -copyts
  801. Do not process input timestamps, but keep their values without trying
  802. to sanitize them. In particular, do not remove the initial start time
  803. offset value.
  804. Note that, depending on the @option{vsync} option or on specific muxer
  805. processing (e.g. in case the format option @option{avoid_negative_ts}
  806. is enabled) the output timestamps may mismatch with the input
  807. timestamps even when this option is selected.
  808. @item -copytb @var{mode}
  809. Specify how to set the encoder timebase when stream copying. @var{mode} is an
  810. integer numeric value, and can assume one of the following values:
  811. @table @option
  812. @item 1
  813. Use the demuxer timebase.
  814. The time base is copied to the output encoder from the corresponding input
  815. demuxer. This is sometimes required to avoid non monotonically increasing
  816. timestamps when copying video streams with variable frame rate.
  817. @item 0
  818. Use the decoder timebase.
  819. The time base is copied to the output encoder from the corresponding input
  820. decoder.
  821. @item -1
  822. Try to make the choice automatically, in order to generate a sane output.
  823. @end table
  824. Default value is -1.
  825. @item -shortest (@emph{output})
  826. Finish encoding when the shortest input stream ends.
  827. @item -dts_delta_threshold
  828. Timestamp discontinuity delta threshold.
  829. @item -muxdelay @var{seconds} (@emph{input})
  830. Set the maximum demux-decode delay.
  831. @item -muxpreload @var{seconds} (@emph{input})
  832. Set the initial demux-decode delay.
  833. @item -streamid @var{output-stream-index}:@var{new-value} (@emph{output})
  834. Assign a new stream-id value to an output stream. This option should be
  835. specified prior to the output filename to which it applies.
  836. For the situation where multiple output files exist, a streamid
  837. may be reassigned to a different value.
  838. For example, to set the stream 0 PID to 33 and the stream 1 PID to 36 for
  839. an output mpegts file:
  840. @example
  841. ffmpeg -i infile -streamid 0:33 -streamid 1:36 out.ts
  842. @end example
  843. @item -bsf[:@var{stream_specifier}] @var{bitstream_filters} (@emph{output,per-stream})
  844. Set bitstream filters for matching streams. @var{bitstream_filters} is
  845. a comma-separated list of bitstream filters. Use the @code{-bsfs} option
  846. to get the list of bitstream filters.
  847. @example
  848. ffmpeg -i h264.mp4 -c:v copy -bsf:v h264_mp4toannexb -an out.h264
  849. @end example
  850. @example
  851. ffmpeg -i file.mov -an -vn -bsf:s mov2textsub -c:s copy -f rawvideo sub.txt
  852. @end example
  853. @item -tag[:@var{stream_specifier}] @var{codec_tag} (@emph{input/output,per-stream})
  854. Force a tag/fourcc for matching streams.
  855. @item -timecode @var{hh}:@var{mm}:@var{ss}SEP@var{ff}
  856. Specify Timecode for writing. @var{SEP} is ':' for non drop timecode and ';'
  857. (or '.') for drop.
  858. @example
  859. ffmpeg -i input.mpg -timecode 01:02:03.04 -r 30000/1001 -s ntsc output.mpg
  860. @end example
  861. @anchor{filter_complex_option}
  862. @item -filter_complex @var{filtergraph} (@emph{global})
  863. Define a complex filtergraph, i.e. one with arbitrary number of inputs and/or
  864. outputs. For simple graphs -- those with one input and one output of the same
  865. type -- see the @option{-filter} options. @var{filtergraph} is a description of
  866. the filtergraph, as described in the ``Filtergraph syntax'' section of the
  867. ffmpeg-filters manual.
  868. Input link labels must refer to input streams using the
  869. @code{[file_index:stream_specifier]} syntax (i.e. the same as @option{-map}
  870. uses). If @var{stream_specifier} matches multiple streams, the first one will be
  871. used. An unlabeled input will be connected to the first unused input stream of
  872. the matching type.
  873. Output link labels are referred to with @option{-map}. Unlabeled outputs are
  874. added to the first output file.
  875. Note that with this option it is possible to use only lavfi sources without
  876. normal input files.
  877. For example, to overlay an image over video
  878. @example
  879. ffmpeg -i video.mkv -i image.png -filter_complex '[0:v][1:v]overlay[out]' -map
  880. '[out]' out.mkv
  881. @end example
  882. Here @code{[0:v]} refers to the first video stream in the first input file,
  883. which is linked to the first (main) input of the overlay filter. Similarly the
  884. first video stream in the second input is linked to the second (overlay) input
  885. of overlay.
  886. Assuming there is only one video stream in each input file, we can omit input
  887. labels, so the above is equivalent to
  888. @example
  889. ffmpeg -i video.mkv -i image.png -filter_complex 'overlay[out]' -map
  890. '[out]' out.mkv
  891. @end example
  892. Furthermore we can omit the output label and the single output from the filter
  893. graph will be added to the output file automatically, so we can simply write
  894. @example
  895. ffmpeg -i video.mkv -i image.png -filter_complex 'overlay' out.mkv
  896. @end example
  897. To generate 5 seconds of pure red video using lavfi @code{color} source:
  898. @example
  899. ffmpeg -filter_complex 'color=c=red' -t 5 out.mkv
  900. @end example
  901. @item -lavfi @var{filtergraph} (@emph{global})
  902. Define a complex filtergraph, i.e. one with arbitrary number of inputs and/or
  903. outputs. Equivalent to @option{-filter_complex}.
  904. @item -filter_complex_script @var{filename} (@emph{global})
  905. This option is similar to @option{-filter_complex}, the only difference is that
  906. its argument is the name of the file from which a complex filtergraph
  907. description is to be read.
  908. @item -accurate_seek (@emph{input})
  909. This option enables or disables accurate seeking in input files with the
  910. @option{-ss} option. It is enabled by default, so seeking is accurate when
  911. transcoding. Use @option{-noaccurate_seek} to disable it, which may be useful
  912. e.g. when copying some streams and transcoding the others.
  913. @item -override_ffserver (@emph{global})
  914. Overrides the input specifications from @command{ffserver}. Using this
  915. option you can map any input stream to @command{ffserver} and control
  916. many aspects of the encoding from @command{ffmpeg}. Without this
  917. option @command{ffmpeg} will transmit to @command{ffserver} what is
  918. requested by @command{ffserver}.
  919. The option is intended for cases where features are needed that cannot be
  920. specified to @command{ffserver} but can be to @command{ffmpeg}.
  921. @end table
  922. As a special exception, you can use a bitmap subtitle stream as input: it
  923. will be converted into a video with the same size as the largest video in
  924. the file, or 720x576 if no video is present. Note that this is an
  925. experimental and temporary solution. It will be removed once libavfilter has
  926. proper support for subtitles.
  927. For example, to hardcode subtitles on top of a DVB-T recording stored in
  928. MPEG-TS format, delaying the subtitles by 1 second:
  929. @example
  930. ffmpeg -i input.ts -filter_complex \
  931. '[#0x2ef] setpts=PTS+1/TB [sub] ; [#0x2d0] [sub] overlay' \
  932. -sn -map '#0x2dc' output.mkv
  933. @end example
  934. (0x2d0, 0x2dc and 0x2ef are the MPEG-TS PIDs of respectively the video,
  935. audio and subtitles streams; 0:0, 0:3 and 0:7 would have worked too)
  936. @section Preset files
  937. A preset file contains a sequence of @var{option}=@var{value} pairs,
  938. one for each line, specifying a sequence of options which would be
  939. awkward to specify on the command line. Lines starting with the hash
  940. ('#') character are ignored and are used to provide comments. Check
  941. the @file{presets} directory in the FFmpeg source tree for examples.
  942. Preset files are specified with the @code{vpre}, @code{apre},
  943. @code{spre}, and @code{fpre} options. The @code{fpre} option takes the
  944. filename of the preset instead of a preset name as input and can be
  945. used for any kind of codec. For the @code{vpre}, @code{apre}, and
  946. @code{spre} options, the options specified in a preset file are
  947. applied to the currently selected codec of the same type as the preset
  948. option.
  949. The argument passed to the @code{vpre}, @code{apre}, and @code{spre}
  950. preset options identifies the preset file to use according to the
  951. following rules:
  952. First ffmpeg searches for a file named @var{arg}.ffpreset in the
  953. directories @file{$FFMPEG_DATADIR} (if set), and @file{$HOME/.ffmpeg}, and in
  954. the datadir defined at configuration time (usually @file{PREFIX/share/ffmpeg})
  955. or in a @file{ffpresets} folder along the executable on win32,
  956. in that order. For example, if the argument is @code{libvpx-1080p}, it will
  957. search for the file @file{libvpx-1080p.ffpreset}.
  958. If no such file is found, then ffmpeg will search for a file named
  959. @var{codec_name}-@var{arg}.ffpreset in the above-mentioned
  960. directories, where @var{codec_name} is the name of the codec to which
  961. the preset file options will be applied. For example, if you select
  962. the video codec with @code{-vcodec libvpx} and use @code{-vpre 1080p},
  963. then it will search for the file @file{libvpx-1080p.ffpreset}.
  964. @c man end OPTIONS
  965. @chapter Tips
  966. @c man begin TIPS
  967. @itemize
  968. @item
  969. For streaming at very low bitrates, use a low frame rate
  970. and a small GOP size. This is especially true for RealVideo where
  971. the Linux player does not seem to be very fast, so it can miss
  972. frames. An example is:
  973. @example
  974. ffmpeg -g 3 -r 3 -t 10 -b:v 50k -s qcif -f rv10 /tmp/b.rm
  975. @end example
  976. @item
  977. The parameter 'q' which is displayed while encoding is the current
  978. quantizer. The value 1 indicates that a very good quality could
  979. be achieved. The value 31 indicates the worst quality. If q=31 appears
  980. too often, it means that the encoder cannot compress enough to meet
  981. your bitrate. You must either increase the bitrate, decrease the
  982. frame rate or decrease the frame size.
  983. @item
  984. If your computer is not fast enough, you can speed up the
  985. compression at the expense of the compression ratio. You can use
  986. '-me zero' to speed up motion estimation, and '-g 0' to disable
  987. motion estimation completely (you have only I-frames, which means it
  988. is about as good as JPEG compression).
  989. @item
  990. To have very low audio bitrates, reduce the sampling frequency
  991. (down to 22050 Hz for MPEG audio, 22050 or 11025 for AC-3).
  992. @item
  993. To have a constant quality (but a variable bitrate), use the option
  994. '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
  995. quality).
  996. @end itemize
  997. @c man end TIPS
  998. @chapter Examples
  999. @c man begin EXAMPLES
  1000. @section Preset files
  1001. A preset file contains a sequence of @var{option=value} pairs, one for
  1002. each line, specifying a sequence of options which can be specified also on
  1003. the command line. Lines starting with the hash ('#') character are ignored and
  1004. are used to provide comments. Empty lines are also ignored. Check the
  1005. @file{presets} directory in the FFmpeg source tree for examples.
  1006. Preset files are specified with the @code{pre} option, this option takes a
  1007. preset name as input. FFmpeg searches for a file named @var{preset_name}.avpreset in
  1008. the directories @file{$AVCONV_DATADIR} (if set), and @file{$HOME/.ffmpeg}, and in
  1009. the data directory defined at configuration time (usually @file{$PREFIX/share/ffmpeg})
  1010. in that order. For example, if the argument is @code{libx264-max}, it will
  1011. search for the file @file{libx264-max.avpreset}.
  1012. @section Video and Audio grabbing
  1013. If you specify the input format and device then ffmpeg can grab video
  1014. and audio directly.
  1015. @example
  1016. ffmpeg -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
  1017. @end example
  1018. Or with an ALSA audio source (mono input, card id 1) instead of OSS:
  1019. @example
  1020. ffmpeg -f alsa -ac 1 -i hw:1 -f video4linux2 -i /dev/video0 /tmp/out.mpg
  1021. @end example
  1022. Note that you must activate the right video source and channel before
  1023. launching ffmpeg with any TV viewer such as
  1024. @uref{http://linux.bytesex.org/xawtv/, xawtv} by Gerd Knorr. You also
  1025. have to set the audio recording levels correctly with a
  1026. standard mixer.
  1027. @section X11 grabbing
  1028. Grab the X11 display with ffmpeg via
  1029. @example
  1030. ffmpeg -f x11grab -video_size cif -framerate 25 -i :0.0 /tmp/out.mpg
  1031. @end example
  1032. 0.0 is display.screen number of your X11 server, same as
  1033. the DISPLAY environment variable.
  1034. @example
  1035. ffmpeg -f x11grab -video_size cif -framerate 25 -i :0.0+10,20 /tmp/out.mpg
  1036. @end example
  1037. 0.0 is display.screen number of your X11 server, same as the DISPLAY environment
  1038. variable. 10 is the x-offset and 20 the y-offset for the grabbing.
  1039. @section Video and Audio file format conversion
  1040. Any supported file format and protocol can serve as input to ffmpeg:
  1041. Examples:
  1042. @itemize
  1043. @item
  1044. You can use YUV files as input:
  1045. @example
  1046. ffmpeg -i /tmp/test%d.Y /tmp/out.mpg
  1047. @end example
  1048. It will use the files:
  1049. @example
  1050. /tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
  1051. /tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
  1052. @end example
  1053. The Y files use twice the resolution of the U and V files. They are
  1054. raw files, without header. They can be generated by all decent video
  1055. decoders. You must specify the size of the image with the @option{-s} option
  1056. if ffmpeg cannot guess it.
  1057. @item
  1058. You can input from a raw YUV420P file:
  1059. @example
  1060. ffmpeg -i /tmp/test.yuv /tmp/out.avi
  1061. @end example
  1062. test.yuv is a file containing raw YUV planar data. Each frame is composed
  1063. of the Y plane followed by the U and V planes at half vertical and
  1064. horizontal resolution.
  1065. @item
  1066. You can output to a raw YUV420P file:
  1067. @example
  1068. ffmpeg -i mydivx.avi hugefile.yuv
  1069. @end example
  1070. @item
  1071. You can set several input files and output files:
  1072. @example
  1073. ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
  1074. @end example
  1075. Converts the audio file a.wav and the raw YUV video file a.yuv
  1076. to MPEG file a.mpg.
  1077. @item
  1078. You can also do audio and video conversions at the same time:
  1079. @example
  1080. ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2
  1081. @end example
  1082. Converts a.wav to MPEG audio at 22050 Hz sample rate.
  1083. @item
  1084. You can encode to several formats at the same time and define a
  1085. mapping from input stream to output streams:
  1086. @example
  1087. ffmpeg -i /tmp/a.wav -map 0:a -b:a 64k /tmp/a.mp2 -map 0:a -b:a 128k /tmp/b.mp2
  1088. @end example
  1089. Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
  1090. file:index' specifies which input stream is used for each output
  1091. stream, in the order of the definition of output streams.
  1092. @item
  1093. You can transcode decrypted VOBs:
  1094. @example
  1095. 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
  1096. @end example
  1097. This is a typical DVD ripping example; the input is a VOB file, the
  1098. output an AVI file with MPEG-4 video and MP3 audio. Note that in this
  1099. command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
  1100. GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
  1101. input video. Furthermore, the audio stream is MP3-encoded so you need
  1102. to enable LAME support by passing @code{--enable-libmp3lame} to configure.
  1103. The mapping is particularly useful for DVD transcoding
  1104. to get the desired audio language.
  1105. NOTE: To see the supported input formats, use @code{ffmpeg -formats}.
  1106. @item
  1107. You can extract images from a video, or create a video from many images:
  1108. For extracting images from a video:
  1109. @example
  1110. ffmpeg -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg
  1111. @end example
  1112. This will extract one video frame per second from the video and will
  1113. output them in files named @file{foo-001.jpeg}, @file{foo-002.jpeg},
  1114. etc. Images will be rescaled to fit the new WxH values.
  1115. If you want to extract just a limited number of frames, you can use the
  1116. above command in combination with the -vframes or -t option, or in
  1117. combination with -ss to start extracting from a certain point in time.
  1118. For creating a video from many images:
  1119. @example
  1120. ffmpeg -f image2 -i foo-%03d.jpeg -r 12 -s WxH foo.avi
  1121. @end example
  1122. The syntax @code{foo-%03d.jpeg} specifies to use a decimal number
  1123. composed of three digits padded with zeroes to express the sequence
  1124. number. It is the same syntax supported by the C printf function, but
  1125. only formats accepting a normal integer are suitable.
  1126. When importing an image sequence, -i also supports expanding
  1127. shell-like wildcard patterns (globbing) internally, by selecting the
  1128. image2-specific @code{-pattern_type glob} option.
  1129. For example, for creating a video from filenames matching the glob pattern
  1130. @code{foo-*.jpeg}:
  1131. @example
  1132. ffmpeg -f image2 -pattern_type glob -i 'foo-*.jpeg' -r 12 -s WxH foo.avi
  1133. @end example
  1134. @item
  1135. You can put many streams of the same type in the output:
  1136. @example
  1137. ffmpeg -i test1.avi -i test2.avi -map 0:3 -map 0:2 -map 0:1 -map 0:0 -c copy test12.nut
  1138. @end example
  1139. The resulting output file @file{test12.avi} will contain first four streams from
  1140. the input file in reverse order.
  1141. @item
  1142. To force CBR video output:
  1143. @example
  1144. ffmpeg -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v
  1145. @end example
  1146. @item
  1147. The four options lmin, lmax, mblmin and mblmax use 'lambda' units,
  1148. but you may use the QP2LAMBDA constant to easily convert from 'q' units:
  1149. @example
  1150. ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext
  1151. @end example
  1152. @end itemize
  1153. @c man end EXAMPLES
  1154. @include config.texi
  1155. @ifset config-all
  1156. @ifset config-avutil
  1157. @include utils.texi
  1158. @end ifset
  1159. @ifset config-avcodec
  1160. @include codecs.texi
  1161. @include bitstream_filters.texi
  1162. @end ifset
  1163. @ifset config-avformat
  1164. @include formats.texi
  1165. @include protocols.texi
  1166. @end ifset
  1167. @ifset config-avdevice
  1168. @include devices.texi
  1169. @end ifset
  1170. @ifset config-swresample
  1171. @include resampler.texi
  1172. @end ifset
  1173. @ifset config-swscale
  1174. @include scaler.texi
  1175. @end ifset
  1176. @ifset config-avfilter
  1177. @include filters.texi
  1178. @end ifset
  1179. @end ifset
  1180. @chapter See Also
  1181. @ifhtml
  1182. @ifset config-all
  1183. @url{ffmpeg.html,ffmpeg}
  1184. @end ifset
  1185. @ifset config-not-all
  1186. @url{ffmpeg-all.html,ffmpeg-all},
  1187. @end ifset
  1188. @url{ffplay.html,ffplay}, @url{ffprobe.html,ffprobe}, @url{ffserver.html,ffserver},
  1189. @url{ffmpeg-utils.html,ffmpeg-utils},
  1190. @url{ffmpeg-scaler.html,ffmpeg-scaler},
  1191. @url{ffmpeg-resampler.html,ffmpeg-resampler},
  1192. @url{ffmpeg-codecs.html,ffmpeg-codecs},
  1193. @url{ffmpeg-bitstream-filters.html,ffmpeg-bitstream-filters},
  1194. @url{ffmpeg-formats.html,ffmpeg-formats},
  1195. @url{ffmpeg-devices.html,ffmpeg-devices},
  1196. @url{ffmpeg-protocols.html,ffmpeg-protocols},
  1197. @url{ffmpeg-filters.html,ffmpeg-filters}
  1198. @end ifhtml
  1199. @ifnothtml
  1200. @ifset config-all
  1201. ffmpeg(1),
  1202. @end ifset
  1203. @ifset config-not-all
  1204. ffmpeg-all(1),
  1205. @end ifset
  1206. ffplay(1), ffprobe(1), ffserver(1),
  1207. ffmpeg-utils(1), ffmpeg-scaler(1), ffmpeg-resampler(1),
  1208. ffmpeg-codecs(1), ffmpeg-bitstream-filters(1), ffmpeg-formats(1),
  1209. ffmpeg-devices(1), ffmpeg-protocols(1), ffmpeg-filters(1)
  1210. @end ifnothtml
  1211. @include authors.texi
  1212. @ignore
  1213. @setfilename ffmpeg
  1214. @settitle ffmpeg video converter
  1215. @end ignore
  1216. @bye