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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 vda
  512. Use Apple VDA hardware acceleration.
  513. @item vdpau
  514. Use VDPAU (Video Decode and Presentation API for Unix) hardware acceleration.
  515. @item dxva2
  516. Use DXVA2 (DirectX Video Acceleration) hardware acceleration.
  517. @end table
  518. This option has no effect if the selected hwaccel is not available or not
  519. supported by the chosen decoder.
  520. Note that most acceleration methods are intended for playback and will not be
  521. faster than software decoding on modern CPUs. Additionally, @command{ffmpeg}
  522. will usually need to copy the decoded frames from the GPU memory into the system
  523. memory, resulting in further performance loss. This option is thus mainly
  524. useful for testing.
  525. @item -hwaccel_device[:@var{stream_specifier}] @var{hwaccel_device} (@emph{input,per-stream})
  526. Select a device to use for hardware acceleration.
  527. This option only makes sense when the @option{-hwaccel} option is also
  528. specified. Its exact meaning depends on the specific hardware acceleration
  529. method chosen.
  530. @table @option
  531. @item vdpau
  532. For VDPAU, this option specifies the X11 display/screen to use. If this option
  533. is not specified, the value of the @var{DISPLAY} environment variable is used
  534. @item dxva2
  535. For DXVA2, this option should contain the number of the display adapter to use.
  536. If this option is not specified, the default adapter is used.
  537. @end table
  538. @end table
  539. @section Audio Options
  540. @table @option
  541. @item -aframes @var{number} (@emph{output})
  542. Set the number of audio frames to record. This is an alias for @code{-frames:a}.
  543. @item -ar[:@var{stream_specifier}] @var{freq} (@emph{input/output,per-stream})
  544. Set the audio sampling frequency. For output streams it is set by
  545. default to the frequency of the corresponding input stream. For input
  546. streams this option only makes sense for audio grabbing devices and raw
  547. demuxers and is mapped to the corresponding demuxer options.
  548. @item -aq @var{q} (@emph{output})
  549. Set the audio quality (codec-specific, VBR). This is an alias for -q:a.
  550. @item -ac[:@var{stream_specifier}] @var{channels} (@emph{input/output,per-stream})
  551. Set the number of audio channels. For output streams it is set by
  552. default to the number of input audio channels. For input streams
  553. this option only makes sense for audio grabbing devices and raw demuxers
  554. and is mapped to the corresponding demuxer options.
  555. @item -an (@emph{output})
  556. Disable audio recording.
  557. @item -acodec @var{codec} (@emph{input/output})
  558. Set the audio codec. This is an alias for @code{-codec:a}.
  559. @item -sample_fmt[:@var{stream_specifier}] @var{sample_fmt} (@emph{output,per-stream})
  560. Set the audio sample format. Use @code{-sample_fmts} to get a list
  561. of supported sample formats.
  562. @item -af @var{filtergraph} (@emph{output})
  563. Create the filtergraph specified by @var{filtergraph} and use it to
  564. filter the stream.
  565. This is an alias for @code{-filter:a}, see the @ref{filter_option,,-filter option}.
  566. @end table
  567. @section Advanced Audio options:
  568. @table @option
  569. @item -atag @var{fourcc/tag} (@emph{output})
  570. Force audio tag/fourcc. This is an alias for @code{-tag:a}.
  571. @item -absf @var{bitstream_filter}
  572. Deprecated, see -bsf
  573. @item -guess_layout_max @var{channels} (@emph{input,per-stream})
  574. If some input channel layout is not known, try to guess only if it
  575. corresponds to at most the specified number of channels. For example, 2
  576. tells to @command{ffmpeg} to recognize 1 channel as mono and 2 channels as
  577. stereo but not 6 channels as 5.1. The default is to always try to guess. Use
  578. 0 to disable all guessing.
  579. @end table
  580. @section Subtitle options:
  581. @table @option
  582. @item -scodec @var{codec} (@emph{input/output})
  583. Set the subtitle codec. This is an alias for @code{-codec:s}.
  584. @item -sn (@emph{output})
  585. Disable subtitle recording.
  586. @item -sbsf @var{bitstream_filter}
  587. Deprecated, see -bsf
  588. @end table
  589. @section Advanced Subtitle options:
  590. @table @option
  591. @item -fix_sub_duration
  592. Fix subtitles durations. For each subtitle, wait for the next packet in the
  593. same stream and adjust the duration of the first to avoid overlap. This is
  594. necessary with some subtitles codecs, especially DVB subtitles, because the
  595. duration in the original packet is only a rough estimate and the end is
  596. actually marked by an empty subtitle frame. Failing to use this option when
  597. necessary can result in exaggerated durations or muxing failures due to
  598. non-monotonic timestamps.
  599. Note that this option will delay the output of all data until the next
  600. subtitle packet is decoded: it may increase memory consumption and latency a
  601. lot.
  602. @item -canvas_size @var{size}
  603. Set the size of the canvas used to render subtitles.
  604. @end table
  605. @section Advanced options
  606. @table @option
  607. @item -map [-]@var{input_file_id}[:@var{stream_specifier}][,@var{sync_file_id}[:@var{stream_specifier}]] | @var{[linklabel]} (@emph{output})
  608. Designate one or more input streams as a source for the output file. Each input
  609. stream is identified by the input file index @var{input_file_id} and
  610. the input stream index @var{input_stream_id} within the input
  611. file. Both indices start at 0. If specified,
  612. @var{sync_file_id}:@var{stream_specifier} sets which input stream
  613. is used as a presentation sync reference.
  614. The first @code{-map} option on the command line specifies the
  615. source for output stream 0, the second @code{-map} option specifies
  616. the source for output stream 1, etc.
  617. A @code{-} character before the stream identifier creates a "negative" mapping.
  618. It disables matching streams from already created mappings.
  619. An alternative @var{[linklabel]} form will map outputs from complex filter
  620. graphs (see the @option{-filter_complex} option) to the output file.
  621. @var{linklabel} must correspond to a defined output link label in the graph.
  622. For example, to map ALL streams from the first input file to output
  623. @example
  624. ffmpeg -i INPUT -map 0 output
  625. @end example
  626. For example, if you have two audio streams in the first input file,
  627. these streams are identified by "0:0" and "0:1". You can use
  628. @code{-map} to select which streams to place in an output file. For
  629. example:
  630. @example
  631. ffmpeg -i INPUT -map 0:1 out.wav
  632. @end example
  633. will map the input stream in @file{INPUT} identified by "0:1" to
  634. the (single) output stream in @file{out.wav}.
  635. For example, to select the stream with index 2 from input file
  636. @file{a.mov} (specified by the identifier "0:2"), and stream with
  637. index 6 from input @file{b.mov} (specified by the identifier "1:6"),
  638. and copy them to the output file @file{out.mov}:
  639. @example
  640. ffmpeg -i a.mov -i b.mov -c copy -map 0:2 -map 1:6 out.mov
  641. @end example
  642. To select all video and the third audio stream from an input file:
  643. @example
  644. ffmpeg -i INPUT -map 0:v -map 0:a:2 OUTPUT
  645. @end example
  646. To map all the streams except the second audio, use negative mappings
  647. @example
  648. ffmpeg -i INPUT -map 0 -map -0:a:1 OUTPUT
  649. @end example
  650. Note that using this option disables the default mappings for this output file.
  651. @item -map_channel [@var{input_file_id}.@var{stream_specifier}.@var{channel_id}|-1][:@var{output_file_id}.@var{stream_specifier}]
  652. Map an audio channel from a given input to an output. If
  653. @var{output_file_id}.@var{stream_specifier} is not set, the audio channel will
  654. be mapped on all the audio streams.
  655. Using "-1" instead of
  656. @var{input_file_id}.@var{stream_specifier}.@var{channel_id} will map a muted
  657. channel.
  658. For example, assuming @var{INPUT} is a stereo audio file, you can switch the
  659. two audio channels with the following command:
  660. @example
  661. ffmpeg -i INPUT -map_channel 0.0.1 -map_channel 0.0.0 OUTPUT
  662. @end example
  663. If you want to mute the first channel and keep the second:
  664. @example
  665. ffmpeg -i INPUT -map_channel -1 -map_channel 0.0.1 OUTPUT
  666. @end example
  667. The order of the "-map_channel" option specifies the order of the channels in
  668. the output stream. The output channel layout is guessed from the number of
  669. channels mapped (mono if one "-map_channel", stereo if two, etc.). Using "-ac"
  670. in combination of "-map_channel" makes the channel gain levels to be updated if
  671. input and output channel layouts don't match (for instance two "-map_channel"
  672. options and "-ac 6").
  673. You can also extract each channel of an input to specific outputs; the following
  674. command extracts two channels of the @var{INPUT} audio stream (file 0, stream 0)
  675. to the respective @var{OUTPUT_CH0} and @var{OUTPUT_CH1} outputs:
  676. @example
  677. ffmpeg -i INPUT -map_channel 0.0.0 OUTPUT_CH0 -map_channel 0.0.1 OUTPUT_CH1
  678. @end example
  679. The following example splits the channels of a stereo input into two separate
  680. streams, which are put into the same output file:
  681. @example
  682. 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
  683. @end example
  684. Note that currently each output stream can only contain channels from a single
  685. input stream; you can't for example use "-map_channel" to pick multiple input
  686. audio channels contained in different streams (from the same or different files)
  687. and merge them into a single output stream. It is therefore not currently
  688. possible, for example, to turn two separate mono streams into a single stereo
  689. stream. However splitting a stereo stream into two single channel mono streams
  690. is possible.
  691. If you need this feature, a possible workaround is to use the @emph{amerge}
  692. filter. For example, if you need to merge a media (here @file{input.mkv}) with 2
  693. mono audio streams into one single stereo channel audio stream (and keep the
  694. video stream), you can use the following command:
  695. @example
  696. ffmpeg -i input.mkv -filter_complex "[0:1] [0:2] amerge" -c:a pcm_s16le -c:v copy output.mkv
  697. @end example
  698. @item -map_metadata[:@var{metadata_spec_out}] @var{infile}[:@var{metadata_spec_in}] (@emph{output,per-metadata})
  699. Set metadata information of the next output file from @var{infile}. Note that
  700. those are file indices (zero-based), not filenames.
  701. Optional @var{metadata_spec_in/out} parameters specify, which metadata to copy.
  702. A metadata specifier can have the following forms:
  703. @table @option
  704. @item @var{g}
  705. global metadata, i.e. metadata that applies to the whole file
  706. @item @var{s}[:@var{stream_spec}]
  707. per-stream metadata. @var{stream_spec} is a stream specifier as described
  708. in the @ref{Stream specifiers} chapter. In an input metadata specifier, the first
  709. matching stream is copied from. In an output metadata specifier, all matching
  710. streams are copied to.
  711. @item @var{c}:@var{chapter_index}
  712. per-chapter metadata. @var{chapter_index} is the zero-based chapter index.
  713. @item @var{p}:@var{program_index}
  714. per-program metadata. @var{program_index} is the zero-based program index.
  715. @end table
  716. If metadata specifier is omitted, it defaults to global.
  717. By default, global metadata is copied from the first input file,
  718. per-stream and per-chapter metadata is copied along with streams/chapters. These
  719. default mappings are disabled by creating any mapping of the relevant type. A negative
  720. file index can be used to create a dummy mapping that just disables automatic copying.
  721. For example to copy metadata from the first stream of the input file to global metadata
  722. of the output file:
  723. @example
  724. ffmpeg -i in.ogg -map_metadata 0:s:0 out.mp3
  725. @end example
  726. To do the reverse, i.e. copy global metadata to all audio streams:
  727. @example
  728. ffmpeg -i in.mkv -map_metadata:s:a 0:g out.mkv
  729. @end example
  730. Note that simple @code{0} would work as well in this example, since global
  731. metadata is assumed by default.
  732. @item -map_chapters @var{input_file_index} (@emph{output})
  733. Copy chapters from input file with index @var{input_file_index} to the next
  734. output file. If no chapter mapping is specified, then chapters are copied from
  735. the first input file with at least one chapter. Use a negative file index to
  736. disable any chapter copying.
  737. @item -benchmark (@emph{global})
  738. Show benchmarking information at the end of an encode.
  739. Shows CPU time used and maximum memory consumption.
  740. Maximum memory consumption is not supported on all systems,
  741. it will usually display as 0 if not supported.
  742. @item -benchmark_all (@emph{global})
  743. Show benchmarking information during the encode.
  744. Shows CPU time used in various steps (audio/video encode/decode).
  745. @item -timelimit @var{duration} (@emph{global})
  746. Exit after ffmpeg has been running for @var{duration} seconds.
  747. @item -dump (@emph{global})
  748. Dump each input packet to stderr.
  749. @item -hex (@emph{global})
  750. When dumping packets, also dump the payload.
  751. @item -re (@emph{input})
  752. Read input at native frame rate. Mainly used to simulate a grab device.
  753. or live input stream (e.g. when reading from a file). Should not be used
  754. with actual grab devices or live input streams (where it can cause packet
  755. loss).
  756. By default @command{ffmpeg} attempts to read the input(s) as fast as possible.
  757. This option will slow down the reading of the input(s) to the native frame rate
  758. of the input(s). It is useful for real-time output (e.g. live streaming).
  759. @item -loop_input
  760. Loop over the input stream. Currently it works only for image
  761. streams. This option is used for automatic FFserver testing.
  762. This option is deprecated, use -loop 1.
  763. @item -loop_output @var{number_of_times}
  764. Repeatedly loop output for formats that support looping such as animated GIF
  765. (0 will loop the output infinitely).
  766. This option is deprecated, use -loop.
  767. @item -vsync @var{parameter}
  768. Video sync method.
  769. For compatibility reasons old values can be specified as numbers.
  770. Newly added values will have to be specified as strings always.
  771. @table @option
  772. @item 0, passthrough
  773. Each frame is passed with its timestamp from the demuxer to the muxer.
  774. @item 1, cfr
  775. Frames will be duplicated and dropped to achieve exactly the requested
  776. constant frame rate.
  777. @item 2, vfr
  778. Frames are passed through with their timestamp or dropped so as to
  779. prevent 2 frames from having the same timestamp.
  780. @item drop
  781. As passthrough but destroys all timestamps, making the muxer generate
  782. fresh timestamps based on frame-rate.
  783. @item -1, auto
  784. Chooses between 1 and 2 depending on muxer capabilities. This is the
  785. default method.
  786. @end table
  787. Note that the timestamps may be further modified by the muxer, after this.
  788. For example, in the case that the format option @option{avoid_negative_ts}
  789. is enabled.
  790. With -map you can select from which stream the timestamps should be
  791. taken. You can leave either video or audio unchanged and sync the
  792. remaining stream(s) to the unchanged one.
  793. @item -async @var{samples_per_second}
  794. Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
  795. the parameter is the maximum samples per second by which the audio is changed.
  796. -async 1 is a special case where only the start of the audio stream is corrected
  797. without any later correction.
  798. Note that the timestamps may be further modified by the muxer, after this.
  799. For example, in the case that the format option @option{avoid_negative_ts}
  800. is enabled.
  801. This option has been deprecated. Use the @code{aresample} audio filter instead.
  802. @item -copyts
  803. Do not process input timestamps, but keep their values without trying
  804. to sanitize them. In particular, do not remove the initial start time
  805. offset value.
  806. Note that, depending on the @option{vsync} option or on specific muxer
  807. processing (e.g. in case the format option @option{avoid_negative_ts}
  808. is enabled) the output timestamps may mismatch with the input
  809. timestamps even when this option is selected.
  810. @item -copytb @var{mode}
  811. Specify how to set the encoder timebase when stream copying. @var{mode} is an
  812. integer numeric value, and can assume one of the following values:
  813. @table @option
  814. @item 1
  815. Use the demuxer timebase.
  816. The time base is copied to the output encoder from the corresponding input
  817. demuxer. This is sometimes required to avoid non monotonically increasing
  818. timestamps when copying video streams with variable frame rate.
  819. @item 0
  820. Use the decoder timebase.
  821. The time base is copied to the output encoder from the corresponding input
  822. decoder.
  823. @item -1
  824. Try to make the choice automatically, in order to generate a sane output.
  825. @end table
  826. Default value is -1.
  827. @item -shortest (@emph{output})
  828. Finish encoding when the shortest input stream ends.
  829. @item -dts_delta_threshold
  830. Timestamp discontinuity delta threshold.
  831. @item -muxdelay @var{seconds} (@emph{input})
  832. Set the maximum demux-decode delay.
  833. @item -muxpreload @var{seconds} (@emph{input})
  834. Set the initial demux-decode delay.
  835. @item -streamid @var{output-stream-index}:@var{new-value} (@emph{output})
  836. Assign a new stream-id value to an output stream. This option should be
  837. specified prior to the output filename to which it applies.
  838. For the situation where multiple output files exist, a streamid
  839. may be reassigned to a different value.
  840. For example, to set the stream 0 PID to 33 and the stream 1 PID to 36 for
  841. an output mpegts file:
  842. @example
  843. ffmpeg -i infile -streamid 0:33 -streamid 1:36 out.ts
  844. @end example
  845. @item -bsf[:@var{stream_specifier}] @var{bitstream_filters} (@emph{output,per-stream})
  846. Set bitstream filters for matching streams. @var{bitstream_filters} is
  847. a comma-separated list of bitstream filters. Use the @code{-bsfs} option
  848. to get the list of bitstream filters.
  849. @example
  850. ffmpeg -i h264.mp4 -c:v copy -bsf:v h264_mp4toannexb -an out.h264
  851. @end example
  852. @example
  853. ffmpeg -i file.mov -an -vn -bsf:s mov2textsub -c:s copy -f rawvideo sub.txt
  854. @end example
  855. @item -tag[:@var{stream_specifier}] @var{codec_tag} (@emph{input/output,per-stream})
  856. Force a tag/fourcc for matching streams.
  857. @item -timecode @var{hh}:@var{mm}:@var{ss}SEP@var{ff}
  858. Specify Timecode for writing. @var{SEP} is ':' for non drop timecode and ';'
  859. (or '.') for drop.
  860. @example
  861. ffmpeg -i input.mpg -timecode 01:02:03.04 -r 30000/1001 -s ntsc output.mpg
  862. @end example
  863. @anchor{filter_complex_option}
  864. @item -filter_complex @var{filtergraph} (@emph{global})
  865. Define a complex filtergraph, i.e. one with arbitrary number of inputs and/or
  866. outputs. For simple graphs -- those with one input and one output of the same
  867. type -- see the @option{-filter} options. @var{filtergraph} is a description of
  868. the filtergraph, as described in the ``Filtergraph syntax'' section of the
  869. ffmpeg-filters manual.
  870. Input link labels must refer to input streams using the
  871. @code{[file_index:stream_specifier]} syntax (i.e. the same as @option{-map}
  872. uses). If @var{stream_specifier} matches multiple streams, the first one will be
  873. used. An unlabeled input will be connected to the first unused input stream of
  874. the matching type.
  875. Output link labels are referred to with @option{-map}. Unlabeled outputs are
  876. added to the first output file.
  877. Note that with this option it is possible to use only lavfi sources without
  878. normal input files.
  879. For example, to overlay an image over video
  880. @example
  881. ffmpeg -i video.mkv -i image.png -filter_complex '[0:v][1:v]overlay[out]' -map
  882. '[out]' out.mkv
  883. @end example
  884. Here @code{[0:v]} refers to the first video stream in the first input file,
  885. which is linked to the first (main) input of the overlay filter. Similarly the
  886. first video stream in the second input is linked to the second (overlay) input
  887. of overlay.
  888. Assuming there is only one video stream in each input file, we can omit input
  889. labels, so the above is equivalent to
  890. @example
  891. ffmpeg -i video.mkv -i image.png -filter_complex 'overlay[out]' -map
  892. '[out]' out.mkv
  893. @end example
  894. Furthermore we can omit the output label and the single output from the filter
  895. graph will be added to the output file automatically, so we can simply write
  896. @example
  897. ffmpeg -i video.mkv -i image.png -filter_complex 'overlay' out.mkv
  898. @end example
  899. To generate 5 seconds of pure red video using lavfi @code{color} source:
  900. @example
  901. ffmpeg -filter_complex 'color=c=red' -t 5 out.mkv
  902. @end example
  903. @item -lavfi @var{filtergraph} (@emph{global})
  904. Define a complex filtergraph, i.e. one with arbitrary number of inputs and/or
  905. outputs. Equivalent to @option{-filter_complex}.
  906. @item -filter_complex_script @var{filename} (@emph{global})
  907. This option is similar to @option{-filter_complex}, the only difference is that
  908. its argument is the name of the file from which a complex filtergraph
  909. description is to be read.
  910. @item -accurate_seek (@emph{input})
  911. This option enables or disables accurate seeking in input files with the
  912. @option{-ss} option. It is enabled by default, so seeking is accurate when
  913. transcoding. Use @option{-noaccurate_seek} to disable it, which may be useful
  914. e.g. when copying some streams and transcoding the others.
  915. @item -override_ffserver (@emph{global})
  916. Overrides the input specifications from @command{ffserver}. Using this
  917. option you can map any input stream to @command{ffserver} and control
  918. many aspects of the encoding from @command{ffmpeg}. Without this
  919. option @command{ffmpeg} will transmit to @command{ffserver} what is
  920. requested by @command{ffserver}.
  921. The option is intended for cases where features are needed that cannot be
  922. specified to @command{ffserver} but can be to @command{ffmpeg}.
  923. @end table
  924. As a special exception, you can use a bitmap subtitle stream as input: it
  925. will be converted into a video with the same size as the largest video in
  926. the file, or 720x576 if no video is present. Note that this is an
  927. experimental and temporary solution. It will be removed once libavfilter has
  928. proper support for subtitles.
  929. For example, to hardcode subtitles on top of a DVB-T recording stored in
  930. MPEG-TS format, delaying the subtitles by 1 second:
  931. @example
  932. ffmpeg -i input.ts -filter_complex \
  933. '[#0x2ef] setpts=PTS+1/TB [sub] ; [#0x2d0] [sub] overlay' \
  934. -sn -map '#0x2dc' output.mkv
  935. @end example
  936. (0x2d0, 0x2dc and 0x2ef are the MPEG-TS PIDs of respectively the video,
  937. audio and subtitles streams; 0:0, 0:3 and 0:7 would have worked too)
  938. @section Preset files
  939. A preset file contains a sequence of @var{option}=@var{value} pairs,
  940. one for each line, specifying a sequence of options which would be
  941. awkward to specify on the command line. Lines starting with the hash
  942. ('#') character are ignored and are used to provide comments. Check
  943. the @file{presets} directory in the FFmpeg source tree for examples.
  944. Preset files are specified with the @code{vpre}, @code{apre},
  945. @code{spre}, and @code{fpre} options. The @code{fpre} option takes the
  946. filename of the preset instead of a preset name as input and can be
  947. used for any kind of codec. For the @code{vpre}, @code{apre}, and
  948. @code{spre} options, the options specified in a preset file are
  949. applied to the currently selected codec of the same type as the preset
  950. option.
  951. The argument passed to the @code{vpre}, @code{apre}, and @code{spre}
  952. preset options identifies the preset file to use according to the
  953. following rules:
  954. First ffmpeg searches for a file named @var{arg}.ffpreset in the
  955. directories @file{$FFMPEG_DATADIR} (if set), and @file{$HOME/.ffmpeg}, and in
  956. the datadir defined at configuration time (usually @file{PREFIX/share/ffmpeg})
  957. or in a @file{ffpresets} folder along the executable on win32,
  958. in that order. For example, if the argument is @code{libvpx-1080p}, it will
  959. search for the file @file{libvpx-1080p.ffpreset}.
  960. If no such file is found, then ffmpeg will search for a file named
  961. @var{codec_name}-@var{arg}.ffpreset in the above-mentioned
  962. directories, where @var{codec_name} is the name of the codec to which
  963. the preset file options will be applied. For example, if you select
  964. the video codec with @code{-vcodec libvpx} and use @code{-vpre 1080p},
  965. then it will search for the file @file{libvpx-1080p.ffpreset}.
  966. @c man end OPTIONS
  967. @chapter Tips
  968. @c man begin TIPS
  969. @itemize
  970. @item
  971. For streaming at very low bitrates, use a low frame rate
  972. and a small GOP size. This is especially true for RealVideo where
  973. the Linux player does not seem to be very fast, so it can miss
  974. frames. An example is:
  975. @example
  976. ffmpeg -g 3 -r 3 -t 10 -b:v 50k -s qcif -f rv10 /tmp/b.rm
  977. @end example
  978. @item
  979. The parameter 'q' which is displayed while encoding is the current
  980. quantizer. The value 1 indicates that a very good quality could
  981. be achieved. The value 31 indicates the worst quality. If q=31 appears
  982. too often, it means that the encoder cannot compress enough to meet
  983. your bitrate. You must either increase the bitrate, decrease the
  984. frame rate or decrease the frame size.
  985. @item
  986. If your computer is not fast enough, you can speed up the
  987. compression at the expense of the compression ratio. You can use
  988. '-me zero' to speed up motion estimation, and '-g 0' to disable
  989. motion estimation completely (you have only I-frames, which means it
  990. is about as good as JPEG compression).
  991. @item
  992. To have very low audio bitrates, reduce the sampling frequency
  993. (down to 22050 Hz for MPEG audio, 22050 or 11025 for AC-3).
  994. @item
  995. To have a constant quality (but a variable bitrate), use the option
  996. '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
  997. quality).
  998. @end itemize
  999. @c man end TIPS
  1000. @chapter Examples
  1001. @c man begin EXAMPLES
  1002. @section Preset files
  1003. A preset file contains a sequence of @var{option=value} pairs, one for
  1004. each line, specifying a sequence of options which can be specified also on
  1005. the command line. Lines starting with the hash ('#') character are ignored and
  1006. are used to provide comments. Empty lines are also ignored. Check the
  1007. @file{presets} directory in the FFmpeg source tree for examples.
  1008. Preset files are specified with the @code{pre} option, this option takes a
  1009. preset name as input. FFmpeg searches for a file named @var{preset_name}.avpreset in
  1010. the directories @file{$AVCONV_DATADIR} (if set), and @file{$HOME/.ffmpeg}, and in
  1011. the data directory defined at configuration time (usually @file{$PREFIX/share/ffmpeg})
  1012. in that order. For example, if the argument is @code{libx264-max}, it will
  1013. search for the file @file{libx264-max.avpreset}.
  1014. @section Video and Audio grabbing
  1015. If you specify the input format and device then ffmpeg can grab video
  1016. and audio directly.
  1017. @example
  1018. ffmpeg -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
  1019. @end example
  1020. Or with an ALSA audio source (mono input, card id 1) instead of OSS:
  1021. @example
  1022. ffmpeg -f alsa -ac 1 -i hw:1 -f video4linux2 -i /dev/video0 /tmp/out.mpg
  1023. @end example
  1024. Note that you must activate the right video source and channel before
  1025. launching ffmpeg with any TV viewer such as
  1026. @uref{http://linux.bytesex.org/xawtv/, xawtv} by Gerd Knorr. You also
  1027. have to set the audio recording levels correctly with a
  1028. standard mixer.
  1029. @section X11 grabbing
  1030. Grab the X11 display with ffmpeg via
  1031. @example
  1032. ffmpeg -f x11grab -video_size cif -framerate 25 -i :0.0 /tmp/out.mpg
  1033. @end example
  1034. 0.0 is display.screen number of your X11 server, same as
  1035. the DISPLAY environment variable.
  1036. @example
  1037. ffmpeg -f x11grab -video_size cif -framerate 25 -i :0.0+10,20 /tmp/out.mpg
  1038. @end example
  1039. 0.0 is display.screen number of your X11 server, same as the DISPLAY environment
  1040. variable. 10 is the x-offset and 20 the y-offset for the grabbing.
  1041. @section Video and Audio file format conversion
  1042. Any supported file format and protocol can serve as input to ffmpeg:
  1043. Examples:
  1044. @itemize
  1045. @item
  1046. You can use YUV files as input:
  1047. @example
  1048. ffmpeg -i /tmp/test%d.Y /tmp/out.mpg
  1049. @end example
  1050. It will use the files:
  1051. @example
  1052. /tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
  1053. /tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
  1054. @end example
  1055. The Y files use twice the resolution of the U and V files. They are
  1056. raw files, without header. They can be generated by all decent video
  1057. decoders. You must specify the size of the image with the @option{-s} option
  1058. if ffmpeg cannot guess it.
  1059. @item
  1060. You can input from a raw YUV420P file:
  1061. @example
  1062. ffmpeg -i /tmp/test.yuv /tmp/out.avi
  1063. @end example
  1064. test.yuv is a file containing raw YUV planar data. Each frame is composed
  1065. of the Y plane followed by the U and V planes at half vertical and
  1066. horizontal resolution.
  1067. @item
  1068. You can output to a raw YUV420P file:
  1069. @example
  1070. ffmpeg -i mydivx.avi hugefile.yuv
  1071. @end example
  1072. @item
  1073. You can set several input files and output files:
  1074. @example
  1075. ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
  1076. @end example
  1077. Converts the audio file a.wav and the raw YUV video file a.yuv
  1078. to MPEG file a.mpg.
  1079. @item
  1080. You can also do audio and video conversions at the same time:
  1081. @example
  1082. ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2
  1083. @end example
  1084. Converts a.wav to MPEG audio at 22050 Hz sample rate.
  1085. @item
  1086. You can encode to several formats at the same time and define a
  1087. mapping from input stream to output streams:
  1088. @example
  1089. ffmpeg -i /tmp/a.wav -map 0:a -b:a 64k /tmp/a.mp2 -map 0:a -b:a 128k /tmp/b.mp2
  1090. @end example
  1091. Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
  1092. file:index' specifies which input stream is used for each output
  1093. stream, in the order of the definition of output streams.
  1094. @item
  1095. You can transcode decrypted VOBs:
  1096. @example
  1097. 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
  1098. @end example
  1099. This is a typical DVD ripping example; the input is a VOB file, the
  1100. output an AVI file with MPEG-4 video and MP3 audio. Note that in this
  1101. command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
  1102. GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
  1103. input video. Furthermore, the audio stream is MP3-encoded so you need
  1104. to enable LAME support by passing @code{--enable-libmp3lame} to configure.
  1105. The mapping is particularly useful for DVD transcoding
  1106. to get the desired audio language.
  1107. NOTE: To see the supported input formats, use @code{ffmpeg -formats}.
  1108. @item
  1109. You can extract images from a video, or create a video from many images:
  1110. For extracting images from a video:
  1111. @example
  1112. ffmpeg -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg
  1113. @end example
  1114. This will extract one video frame per second from the video and will
  1115. output them in files named @file{foo-001.jpeg}, @file{foo-002.jpeg},
  1116. etc. Images will be rescaled to fit the new WxH values.
  1117. If you want to extract just a limited number of frames, you can use the
  1118. above command in combination with the -vframes or -t option, or in
  1119. combination with -ss to start extracting from a certain point in time.
  1120. For creating a video from many images:
  1121. @example
  1122. ffmpeg -f image2 -i foo-%03d.jpeg -r 12 -s WxH foo.avi
  1123. @end example
  1124. The syntax @code{foo-%03d.jpeg} specifies to use a decimal number
  1125. composed of three digits padded with zeroes to express the sequence
  1126. number. It is the same syntax supported by the C printf function, but
  1127. only formats accepting a normal integer are suitable.
  1128. When importing an image sequence, -i also supports expanding
  1129. shell-like wildcard patterns (globbing) internally, by selecting the
  1130. image2-specific @code{-pattern_type glob} option.
  1131. For example, for creating a video from filenames matching the glob pattern
  1132. @code{foo-*.jpeg}:
  1133. @example
  1134. ffmpeg -f image2 -pattern_type glob -i 'foo-*.jpeg' -r 12 -s WxH foo.avi
  1135. @end example
  1136. @item
  1137. You can put many streams of the same type in the output:
  1138. @example
  1139. ffmpeg -i test1.avi -i test2.avi -map 0:3 -map 0:2 -map 0:1 -map 0:0 -c copy test12.nut
  1140. @end example
  1141. The resulting output file @file{test12.avi} will contain first four streams from
  1142. the input file in reverse order.
  1143. @item
  1144. To force CBR video output:
  1145. @example
  1146. ffmpeg -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v
  1147. @end example
  1148. @item
  1149. The four options lmin, lmax, mblmin and mblmax use 'lambda' units,
  1150. but you may use the QP2LAMBDA constant to easily convert from 'q' units:
  1151. @example
  1152. ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext
  1153. @end example
  1154. @end itemize
  1155. @c man end EXAMPLES
  1156. @include config.texi
  1157. @ifset config-all
  1158. @ifset config-avutil
  1159. @include utils.texi
  1160. @end ifset
  1161. @ifset config-avcodec
  1162. @include codecs.texi
  1163. @include bitstream_filters.texi
  1164. @end ifset
  1165. @ifset config-avformat
  1166. @include formats.texi
  1167. @include protocols.texi
  1168. @end ifset
  1169. @ifset config-avdevice
  1170. @include devices.texi
  1171. @end ifset
  1172. @ifset config-swresample
  1173. @include resampler.texi
  1174. @end ifset
  1175. @ifset config-swscale
  1176. @include scaler.texi
  1177. @end ifset
  1178. @ifset config-avfilter
  1179. @include filters.texi
  1180. @end ifset
  1181. @end ifset
  1182. @chapter See Also
  1183. @ifhtml
  1184. @ifset config-all
  1185. @url{ffmpeg.html,ffmpeg}
  1186. @end ifset
  1187. @ifset config-not-all
  1188. @url{ffmpeg-all.html,ffmpeg-all},
  1189. @end ifset
  1190. @url{ffplay.html,ffplay}, @url{ffprobe.html,ffprobe}, @url{ffserver.html,ffserver},
  1191. @url{ffmpeg-utils.html,ffmpeg-utils},
  1192. @url{ffmpeg-scaler.html,ffmpeg-scaler},
  1193. @url{ffmpeg-resampler.html,ffmpeg-resampler},
  1194. @url{ffmpeg-codecs.html,ffmpeg-codecs},
  1195. @url{ffmpeg-bitstream-filters.html,ffmpeg-bitstream-filters},
  1196. @url{ffmpeg-formats.html,ffmpeg-formats},
  1197. @url{ffmpeg-devices.html,ffmpeg-devices},
  1198. @url{ffmpeg-protocols.html,ffmpeg-protocols},
  1199. @url{ffmpeg-filters.html,ffmpeg-filters}
  1200. @end ifhtml
  1201. @ifnothtml
  1202. @ifset config-all
  1203. ffmpeg(1),
  1204. @end ifset
  1205. @ifset config-not-all
  1206. ffmpeg-all(1),
  1207. @end ifset
  1208. ffplay(1), ffprobe(1), ffserver(1),
  1209. ffmpeg-utils(1), ffmpeg-scaler(1), ffmpeg-resampler(1),
  1210. ffmpeg-codecs(1), ffmpeg-bitstream-filters(1), ffmpeg-formats(1),
  1211. ffmpeg-devices(1), ffmpeg-protocols(1), ffmpeg-filters(1)
  1212. @end ifnothtml
  1213. @include authors.texi
  1214. @ignore
  1215. @setfilename ffmpeg
  1216. @settitle ffmpeg video converter
  1217. @end ignore
  1218. @bye