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