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