avconv_opt: Add an option that lists all supported hwaccels
[libav.git] / doc / avconv.texi
1 \input texinfo @c -*- texinfo -*-
3 @settitle avconv Documentation
4 @titlepage
5 @center @titlefont{avconv Documentation}
6 @end titlepage
8 @top
10 @contents
12 @chapter Synopsis
14 The generic syntax is:
16 @example
17 @c man begin SYNOPSIS
18 avconv [global options] [[infile options][@option{-i} @var{infile}]]... @{[outfile options] @var{outfile}@}...
19 @c man end
20 @end example
22 @chapter Description
23 @c man begin DESCRIPTION
25 avconv is a very fast video and audio converter that can also grab from
26 a live audio/video source. It can also convert between arbitrary sample
27 rates and resize video on the fly with a high quality polyphase filter.
29 avconv reads from an arbitrary number of input "files" (which can be regular
30 files, pipes, network streams, grabbing devices, etc.), specified by the
31 @code{-i} option, and writes to an arbitrary number of output "files", which are
32 specified by a plain output filename. Anything found on the command line which
33 cannot be interpreted as an option is considered to be an output filename.
35 Each input or output file can in principle contain any number of streams of
36 different types (video/audio/subtitle/attachment/data). Allowed number and/or
37 types of streams can be limited by the container format. Selecting, which
38 streams from which inputs go into output, is done either automatically or with
39 the @code{-map} option (see the Stream selection chapter).
41 To refer to input files in options, you must use their indices (0-based). E.g.
42 the first input file is @code{0}, the second is @code{1} etc. Similarly, streams
43 within a file are referred to by their indices. E.g. @code{2:3} refers to the
44 fourth stream in the third input file. See also the Stream specifiers chapter.
46 As a general rule, options are applied to the next specified
47 file. Therefore, order is important, and you can have the same
48 option on the command line multiple times. Each occurrence is
49 then applied to the next input or output file.
50 Exceptions from this rule are the global options (e.g. verbosity level),
51 which should be specified first.
53 Do not mix input and output files -- first specify all input files, then all
54 output files. Also do not mix options which belong to different files. All
55 options apply ONLY to the next input or output file and are reset between files.
57 @itemize
58 @item
59 To set the video bitrate of the output file to 64kbit/s:
60 @example
61 avconv -i input.avi -b 64k output.avi
62 @end example
64 @item
65 To force the frame rate of the output file to 24 fps:
66 @example
67 avconv -i input.avi -r 24 output.avi
68 @end example
70 @item
71 To force the frame rate of the input file (valid for raw formats only)
72 to 1 fps and the frame rate of the output file to 24 fps:
73 @example
74 avconv -r 1 -i input.m2v -r 24 output.avi
75 @end example
76 @end itemize
78 The format option may be needed for raw input files.
80 @c man end DESCRIPTION
82 @chapter Detailed description
85 The transcoding process in @command{avconv} for each output can be described by
86 the following diagram:
88 @example
89 _______ ______________
90 | | | |
91 | input | demuxer | encoded data | decoder
92 | file | ---------> | packets | -----+
93 |_______| |______________| |
94 v
95 _________
96 | |
97 | decoded |
98 | frames |
99 |_________|
100 ________ ______________ |
101 | | | | |
102 | output | <-------- | encoded data | <----+
103 | file | muxer | packets | encoder
104 |________| |______________|
107 @end example
109 @command{avconv} calls the libavformat library (containing demuxers) to read
110 input files and get packets containing encoded data from them. When there are
111 multiple input files, @command{avconv} tries to keep them synchronized by
112 tracking lowest timestamp on any active input stream.
114 Encoded packets are then passed to the decoder (unless streamcopy is selected
115 for the stream, see further for a description). The decoder produces
116 uncompressed frames (raw video/PCM audio/...) which can be processed further by
117 filtering (see next section). After filtering the frames are passed to the
118 encoder, which encodes them and outputs encoded packets again. Finally those are
119 passed to the muxer, which writes the encoded packets to the output file.
121 @section Filtering
122 Before encoding, @command{avconv} can process raw audio and video frames using
123 filters from the libavfilter library. Several chained filters form a filter
124 graph. @command{avconv} distinguishes between two types of filtergraphs -
125 simple and complex.
127 @subsection Simple filtergraphs
128 Simple filtergraphs are those that have exactly one input and output, both of
129 the same type. In the above diagram they can be represented by simply inserting
130 an additional step between decoding and encoding:
132 @example
133 _________ ______________
134 | | | |
135 | decoded | | encoded data |
136 | frames |\ /| packets |
137 |_________| \ / |______________|
138 \ __________ /
139 simple \ | | / encoder
140 filtergraph \| filtered |/
141 | frames |
142 |__________|
144 @end example
146 Simple filtergraphs are configured with the per-stream @option{-filter} option
147 (with @option{-vf} and @option{-af} aliases for video and audio respectively).
148 A simple filtergraph for video can look for example like this:
150 @example
151 _______ _____________ _______ ________
152 | | | | | | | |
153 | input | ---> | deinterlace | ---> | scale | ---> | output |
154 |_______| |_____________| |_______| |________|
156 @end example
158 Note that some filters change frame properties but not frame contents. E.g. the
159 @code{fps} filter in the example above changes number of frames, but does not
160 touch the frame contents. Another example is the @code{setpts} filter, which
161 only sets timestamps and otherwise passes the frames unchanged.
163 @subsection Complex filtergraphs
164 Complex filtergraphs are those which cannot be described as simply a linear
165 processing chain applied to one stream. This is the case e.g. when the graph has
166 more than one input and/or output, or when output stream type is different from
167 input. They can be represented with the following diagram:
169 @example
170 _________
171 | |
172 | input 0 |\ __________
173 |_________| \ | |
174 \ _________ /| output 0 |
175 \ | | / |__________|
176 _________ \| complex | /
177 | | | |/
178 | input 1 |---->| filter |\
179 |_________| | | \ __________
180 /| graph | \ | |
181 / | | \| output 1 |
182 _________ / |_________| |__________|
183 | | /
184 | input 2 |/
185 |_________|
187 @end example
189 Complex filtergraphs are configured with the @option{-filter_complex} option.
190 Note that this option is global, since a complex filtergraph by its nature
191 cannot be unambiguously associated with a single stream or file.
193 A trivial example of a complex filtergraph is the @code{overlay} filter, which
194 has two video inputs and one video output, containing one video overlaid on top
195 of the other. Its audio counterpart is the @code{amix} filter.
197 @section Stream copy
198 Stream copy is a mode selected by supplying the @code{copy} parameter to the
199 @option{-codec} option. It makes @command{avconv} omit the decoding and encoding
200 step for the specified stream, so it does only demuxing and muxing. It is useful
201 for changing the container format or modifying container-level metadata. The
202 diagram above will in this case simplify to this:
204 @example
205 _______ ______________ ________
206 | | | | | |
207 | input | demuxer | encoded data | muxer | output |
208 | file | ---------> | packets | -------> | file |
209 |_______| |______________| |________|
211 @end example
213 Since there is no decoding or encoding, it is very fast and there is no quality
214 loss. However it might not work in some cases because of many factors. Applying
215 filters is obviously also impossible, since filters work on uncompressed data.
219 @chapter Stream selection
220 @c man begin STREAM SELECTION
222 By default avconv tries to pick the "best" stream of each type present in input
223 files and add them to each output file. For video, this means the highest
224 resolution, for audio the highest channel count. For subtitle it's simply the
225 first subtitle stream.
227 You can disable some of those defaults by using @code{-vn/-an/-sn} options. For
228 full manual control, use the @code{-map} option, which disables the defaults just
229 described.
231 @c man end STREAM SELECTION
233 @chapter Options
234 @c man begin OPTIONS
236 @include avtools-common-opts.texi
238 @section Main options
240 @table @option
242 @item -f @var{fmt} (@emph{input/output})
243 Force input or output file format. The format is normally autodetected for input
244 files and guessed from file extension for output files, so this option is not
245 needed in most cases.
247 @item -i @var{filename} (@emph{input})
248 input file name
250 @item -y (@emph{global})
251 Overwrite output files without asking.
253 @item -n (@emph{global})
254 Immediately exit when output files already exist.
256 @item -c[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
257 @itemx -codec[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
258 Select an encoder (when used before an output file) or a decoder (when used
259 before an input file) for one or more streams. @var{codec} is the name of a
260 decoder/encoder or a special value @code{copy} (output only) to indicate that
261 the stream is not to be reencoded.
263 For example
264 @example
265 avconv -i INPUT -map 0 -c:v libx264 -c:a copy OUTPUT
266 @end example
267 encodes all video streams with libx264 and copies all audio streams.
269 For each stream, the last matching @code{c} option is applied, so
270 @example
271 avconv -i INPUT -map 0 -c copy -c:v:1 libx264 -c:a:137 libvorbis OUTPUT
272 @end example
273 will copy all the streams except the second video, which will be encoded with
274 libx264, and the 138th audio, which will be encoded with libvorbis.
276 @item -t @var{duration} (@emph{output})
277 Stop writing the output after its duration reaches @var{duration}.
278 @var{duration} may be a number in seconds, or in @code{hh:mm:ss[.xxx]} form.
280 @item -fs @var{limit_size} (@emph{output})
281 Set the file size limit.
283 @item -ss @var{position} (@emph{input/output})
284 When used as an input option (before @code{-i}), seeks in this input file to
285 @var{position}. Note the in most formats it is not possible to seek exactly, so
286 @command{avconv} will seek to the closest seek point before @var{position}.
287 When transcoding and @option{-accurate_seek} is enabled (the default), this
288 extra segment between the seek point and @var{position} will be decoded and
289 discarded. When doing stream copy or when @option{-noaccurate_seek} is used, it
290 will be preserved.
292 When used as an output option (before an output filename), decodes but discards
293 input until the timestamps reach @var{position}.
295 @var{position} may be either in seconds or in @code{hh:mm:ss[.xxx]} form.
297 @item -itsoffset @var{offset} (@emph{input})
298 Set the input time offset in seconds.
299 @code{[-]hh:mm:ss[.xxx]} syntax is also supported.
300 The offset is added to the timestamps of the input files.
301 Specifying a positive offset means that the corresponding
302 streams are delayed by @var{offset} seconds.
304 @item -metadata[:metadata_specifier] @var{key}=@var{value} (@emph{output,per-metadata})
305 Set a metadata key/value pair.
307 An optional @var{metadata_specifier} may be given to set metadata
308 on streams or chapters. See @code{-map_metadata} documentation for
309 details.
311 This option overrides metadata set with @code{-map_metadata}. It is
312 also possible to delete metadata by using an empty value.
314 For example, for setting the title in the output file:
315 @example
316 avconv -i in.avi -metadata title="my title" out.flv
317 @end example
319 To set the language of the first audio stream:
320 @example
321 avconv -i INPUT -metadata:s:a:0 language=eng OUTPUT
322 @end example
324 @item -target @var{type} (@emph{output})
325 Specify target file type (@code{vcd}, @code{svcd}, @code{dvd}, @code{dv},
326 @code{dv50}). @var{type} may be prefixed with @code{pal-}, @code{ntsc-} or
327 @code{film-} to use the corresponding standard. All the format options
328 (bitrate, codecs, buffer sizes) are then set automatically. You can just type:
330 @example
331 avconv -i myfile.avi -target vcd /tmp/vcd.mpg
332 @end example
334 Nevertheless you can specify additional options as long as you know
335 they do not conflict with the standard, as in:
337 @example
338 avconv -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
339 @end example
341 @item -dframes @var{number} (@emph{output})
342 Set the number of data frames to record. This is an alias for @code{-frames:d}.
344 @item -frames[:@var{stream_specifier}] @var{framecount} (@emph{output,per-stream})
345 Stop writing to the stream after @var{framecount} frames.
347 @item -q[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
348 @itemx -qscale[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
349 Use fixed quality scale (VBR). The meaning of @var{q} is
350 codec-dependent.
352 @item -filter[:@var{stream_specifier}] @var{filter_graph} (@emph{output,per-stream})
353 @var{filter_graph} is a description of the filter graph to apply to
354 the stream. Use @code{-filters} to show all the available filters
355 (including also sources and sinks).
357 See also the @option{-filter_complex} option if you want to create filter graphs
358 with multiple inputs and/or outputs.
360 @item -filter_script[:@var{stream_specifier}] @var{filename} (@emph{output,per-stream})
361 This option is similar to @option{-filter}, the only difference is that its
362 argument is the name of the file from which a filtergraph description is to be
363 read.
365 @item -pre[:@var{stream_specifier}] @var{preset_name} (@emph{output,per-stream})
366 Specify the preset for matching stream(s).
368 @item -stats (@emph{global})
369 Print encoding progress/statistics. On by default.
371 @item -attach @var{filename} (@emph{output})
372 Add an attachment to the output file. This is supported by a few formats
373 like Matroska for e.g. fonts used in rendering subtitles. Attachments
374 are implemented as a specific type of stream, so this option will add
375 a new stream to the file. It is then possible to use per-stream options
376 on this stream in the usual way. Attachment streams created with this
377 option will be created after all the other streams (i.e. those created
378 with @code{-map} or automatic mappings).
380 Note that for Matroska you also have to set the mimetype metadata tag:
381 @example
382 avconv -i INPUT -attach DejaVuSans.ttf -metadata:s:2 mimetype=application/x-truetype-font out.mkv
383 @end example
384 (assuming that the attachment stream will be third in the output file).
386 @item -dump_attachment[:@var{stream_specifier}] @var{filename} (@emph{input,per-stream})
387 Extract the matching attachment stream into a file named @var{filename}. If
388 @var{filename} is empty, then the value of the @code{filename} metadata tag
389 will be used.
391 E.g. to extract the first attachment to a file named 'out.ttf':
392 @example
393 avconv -dump_attachment:t:0 out.ttf INPUT
394 @end example
395 To extract all attachments to files determined by the @code{filename} tag:
396 @example
397 avconv -dump_attachment:t "" INPUT
398 @end example
400 Technical note -- attachments are implemented as codec extradata, so this
401 option can actually be used to extract extradata from any stream, not just
402 attachments.
404 @item -noautorotate
405 Disable automatically rotating video based on file metadata.
407 @end table
409 @section Video Options
411 @table @option
412 @item -vframes @var{number} (@emph{output})
413 Set the number of video frames to record. This is an alias for @code{-frames:v}.
414 @item -r[:@var{stream_specifier}] @var{fps} (@emph{input/output,per-stream})
415 Set frame rate (Hz value, fraction or abbreviation).
417 As an input option, ignore any timestamps stored in the file and instead
418 generate timestamps assuming constant frame rate @var{fps}.
420 As an output option, duplicate or drop input frames to achieve constant output
421 frame rate @var{fps} (note that this actually causes the @code{fps} filter to be
422 inserted to the end of the corresponding filtergraph).
424 @item -s[:@var{stream_specifier}] @var{size} (@emph{input/output,per-stream})
425 Set frame size.
427 As an input option, this is a shortcut for the @option{video_size} private
428 option, recognized by some demuxers for which the frame size is either not
429 stored in the file or is configurable -- e.g. raw video or video grabbers.
431 As an output option, this inserts the @code{scale} video filter to the
432 @emph{end} of the corresponding filtergraph. Please use the @code{scale} filter
433 directly to insert it at the beginning or some other place.
435 The format is @samp{wxh} (default - same as source). The following
436 abbreviations are recognized:
437 @table @samp
438 @item sqcif
439 128x96
440 @item qcif
441 176x144
442 @item cif
443 352x288
444 @item 4cif
445 704x576
446 @item 16cif
447 1408x1152
448 @item qqvga
449 160x120
450 @item qvga
451 320x240
452 @item vga
453 640x480
454 @item svga
455 800x600
456 @item xga
457 1024x768
458 @item uxga
459 1600x1200
460 @item qxga
461 2048x1536
462 @item sxga
463 1280x1024
464 @item qsxga
465 2560x2048
466 @item hsxga
467 5120x4096
468 @item wvga
469 852x480
470 @item wxga
471 1366x768
472 @item wsxga
473 1600x1024
474 @item wuxga
475 1920x1200
476 @item woxga
477 2560x1600
478 @item wqsxga
479 3200x2048
480 @item wquxga
481 3840x2400
482 @item whsxga
483 6400x4096
484 @item whuxga
485 7680x4800
486 @item cga
487 320x200
488 @item ega
489 640x350
490 @item hd480
491 852x480
492 @item hd720
493 1280x720
494 @item hd1080
495 1920x1080
496 @item 2kdci
497 2048x1080
498 @item 4kdci
499 4096x2160
500 @item uhd2160
501 3840x2160
502 @item uhd4320
503 7680x4320
504 @end table
506 @item -aspect[:@var{stream_specifier}] @var{aspect} (@emph{output,per-stream})
507 Set the video display aspect ratio specified by @var{aspect}.
509 @var{aspect} can be a floating point number string, or a string of the
510 form @var{num}:@var{den}, where @var{num} and @var{den} are the
511 numerator and denominator of the aspect ratio. For example "4:3",
512 "16:9", "1.3333", and "1.7777" are valid argument values.
514 @item -vn (@emph{output})
515 Disable video recording.
517 @item -vcodec @var{codec} (@emph{output})
518 Set the video codec. This is an alias for @code{-codec:v}.
520 @item -pass[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
521 Select the pass number (1 or 2). It is used to do two-pass
522 video encoding. The statistics of the video are recorded in the first
523 pass into a log file (see also the option -passlogfile),
524 and in the second pass that log file is used to generate the video
525 at the exact requested bitrate.
526 On pass 1, you may just deactivate audio and set output to null,
527 examples for Windows and Unix:
528 @example
529 avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y NUL
530 avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null
531 @end example
533 @item -passlogfile[:@var{stream_specifier}] @var{prefix} (@emph{output,per-stream})
534 Set two-pass log file name prefix to @var{prefix}, the default file name
535 prefix is ``av2pass''. The complete file name will be
536 @file{PREFIX-N.log}, where N is a number specific to the output
537 stream.
539 @item -vf @var{filter_graph} (@emph{output})
540 @var{filter_graph} is a description of the filter graph to apply to
541 the input video.
542 Use the option "-filters" to show all the available filters (including
543 also sources and sinks). This is an alias for @code{-filter:v}.
545 @end table
547 @section Advanced Video Options
549 @table @option
550 @item -pix_fmt[:@var{stream_specifier}] @var{format} (@emph{input/output,per-stream})
551 Set pixel format. Use @code{-pix_fmts} to show all the supported
552 pixel formats.
553 @item -sws_flags @var{flags} (@emph{input/output})
554 Set SwScaler flags.
555 @item -vdt @var{n}
556 Discard threshold.
558 @item -rc_override[:@var{stream_specifier}] @var{override} (@emph{output,per-stream})
559 rate control override for specific intervals
561 @item -vstats
562 Dump video coding statistics to @file{vstats_HHMMSS.log}.
563 @item -vstats_file @var{file}
564 Dump video coding statistics to @var{file}.
565 @item -top[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
566 top=1/bottom=0/auto=-1 field first
567 @item -dc @var{precision}
568 Intra_dc_precision.
569 @item -vtag @var{fourcc/tag} (@emph{output})
570 Force video tag/fourcc. This is an alias for @code{-tag:v}.
571 @item -qphist (@emph{global})
572 Show QP histogram.
573 @item -force_key_frames[:@var{stream_specifier}] @var{time}[,@var{time}...] (@emph{output,per-stream})
574 Force key frames at the specified timestamps, more precisely at the first
575 frames after each specified time.
576 This option can be useful to ensure that a seek point is present at a
577 chapter mark or any other designated place in the output file.
578 The timestamps must be specified in ascending order.
580 @item -copyinkf[:@var{stream_specifier}] (@emph{output,per-stream})
581 When doing stream copy, copy also non-key frames found at the
582 beginning.
584 @item -hwaccel[:@var{stream_specifier}] @var{hwaccel} (@emph{input,per-stream})
585 Use hardware acceleration to decode the matching stream(s). The allowed values
586 of @var{hwaccel} are:
587 @table @option
588 @item none
589 Do not use any hardware acceleration (the default).
591 @item auto
592 Automatically select the hardware acceleration method.
594 @item vda
595 Use Apple VDA hardware acceleration.
597 @item vdpau
598 Use VDPAU (Video Decode and Presentation API for Unix) hardware acceleration.
600 @item dxva2
601 Use DXVA2 (DirectX Video Acceleration) hardware acceleration.
602 @end table
604 This option has no effect if the selected hwaccel is not available or not
605 supported by the chosen decoder.
607 Note that most acceleration methods are intended for playback and will not be
608 faster than software decoding on modern CPUs. Additionally, @command{avconv}
609 will usually need to copy the decoded frames from the GPU memory into the system
610 memory, resulting in further performance loss. This option is thus mainly
611 useful for testing.
613 @item -hwaccel_device[:@var{stream_specifier}] @var{hwaccel_device} (@emph{input,per-stream})
614 Select a device to use for hardware acceleration.
616 This option only makes sense when the @option{-hwaccel} option is also
617 specified. Its exact meaning depends on the specific hardware acceleration
618 method chosen.
620 @table @option
621 @item vdpau
622 For VDPAU, this option specifies the X11 display/screen to use. If this option
623 is not specified, the value of the @var{DISPLAY} environment variable is used
625 @item dxva2
626 For DXVA2, this option should contain the number of the display adapter to use.
627 If this option is not specified, the default adapter is used.
628 @end table
630 @item -hwaccels
631 List all hardware acceleration methods supported in this build of avconv.
633 @end table
635 @section Audio Options
637 @table @option
638 @item -aframes @var{number} (@emph{output})
639 Set the number of audio frames to record. This is an alias for @code{-frames:a}.
640 @item -ar[:@var{stream_specifier}] @var{freq} (@emph{input/output,per-stream})
641 Set the audio sampling frequency. For output streams it is set by
642 default to the frequency of the corresponding input stream. For input
643 streams this option only makes sense for audio grabbing devices and raw
644 demuxers and is mapped to the corresponding demuxer options.
645 @item -aq @var{q} (@emph{output})
646 Set the audio quality (codec-specific, VBR). This is an alias for -q:a.
647 @item -ac[:@var{stream_specifier}] @var{channels} (@emph{input/output,per-stream})
648 Set the number of audio channels. For output streams it is set by
649 default to the number of input audio channels. For input streams
650 this option only makes sense for audio grabbing devices and raw demuxers
651 and is mapped to the corresponding demuxer options.
652 @item -an (@emph{output})
653 Disable audio recording.
654 @item -acodec @var{codec} (@emph{input/output})
655 Set the audio codec. This is an alias for @code{-codec:a}.
656 @item -sample_fmt[:@var{stream_specifier}] @var{sample_fmt} (@emph{output,per-stream})
657 Set the audio sample format. Use @code{-sample_fmts} to get a list
658 of supported sample formats.
659 @item -af @var{filter_graph} (@emph{output})
660 @var{filter_graph} is a description of the filter graph to apply to
661 the input audio.
662 Use the option "-filters" to show all the available filters (including
663 also sources and sinks). This is an alias for @code{-filter:a}.
664 @end table
666 @section Advanced Audio options:
668 @table @option
669 @item -atag @var{fourcc/tag} (@emph{output})
670 Force audio tag/fourcc. This is an alias for @code{-tag:a}.
671 @end table
673 @section Subtitle options:
675 @table @option
676 @item -scodec @var{codec} (@emph{input/output})
677 Set the subtitle codec. This is an alias for @code{-codec:s}.
678 @item -sn (@emph{output})
679 Disable subtitle recording.
680 @end table
682 @section Advanced options
684 @table @option
685 @item -map [-]@var{input_file_id}[:@var{stream_specifier}][,@var{sync_file_id}[:@var{stream_specifier}]] | @var{[linklabel]} (@emph{output})
687 Designate one or more input streams as a source for the output file. Each input
688 stream is identified by the input file index @var{input_file_id} and
689 the input stream index @var{input_stream_id} within the input
690 file. Both indices start at 0. If specified,
691 @var{sync_file_id}:@var{stream_specifier} sets which input stream
692 is used as a presentation sync reference.
694 The first @code{-map} option on the command line specifies the
695 source for output stream 0, the second @code{-map} option specifies
696 the source for output stream 1, etc.
698 A @code{-} character before the stream identifier creates a "negative" mapping.
699 It disables matching streams from already created mappings.
701 An alternative @var{[linklabel]} form will map outputs from complex filter
702 graphs (see the @option{-filter_complex} option) to the output file.
703 @var{linklabel} must correspond to a defined output link label in the graph.
705 For example, to map ALL streams from the first input file to output
706 @example
707 avconv -i INPUT -map 0 output
708 @end example
710 For example, if you have two audio streams in the first input file,
711 these streams are identified by "0:0" and "0:1". You can use
712 @code{-map} to select which streams to place in an output file. For
713 example:
714 @example
715 avconv -i INPUT -map 0:1 out.wav
716 @end example
717 will map the input stream in @file{INPUT} identified by "0:1" to
718 the (single) output stream in @file{out.wav}.
720 For example, to select the stream with index 2 from input file
721 @file{a.mov} (specified by the identifier "0:2"), and stream with
722 index 6 from input @file{b.mov} (specified by the identifier "1:6"),
723 and copy them to the output file @file{out.mov}:
724 @example
725 avconv -i a.mov -i b.mov -c copy -map 0:2 -map 1:6 out.mov
726 @end example
728 To select all video and the third audio stream from an input file:
729 @example
730 avconv -i INPUT -map 0:v -map 0:a:2 OUTPUT
731 @end example
733 To map all the streams except the second audio, use negative mappings
734 @example
735 avconv -i INPUT -map 0 -map -0:a:1 OUTPUT
736 @end example
738 To pick the English audio stream:
739 @example
740 avconv -i INPUT -map 0:m:language:eng OUTPUT
741 @end example
743 Note that using this option disables the default mappings for this output file.
745 @item -map_metadata[:@var{metadata_spec_out}] @var{infile}[:@var{metadata_spec_in}] (@emph{output,per-metadata})
746 Set metadata information of the next output file from @var{infile}. Note that
747 those are file indices (zero-based), not filenames.
748 Optional @var{metadata_spec_in/out} parameters specify, which metadata to copy.
749 A metadata specifier can have the following forms:
750 @table @option
751 @item @var{g}
752 global metadata, i.e. metadata that applies to the whole file
754 @item @var{s}[:@var{stream_spec}]
755 per-stream metadata. @var{stream_spec} is a stream specifier as described
756 in the @ref{Stream specifiers} chapter. In an input metadata specifier, the first
757 matching stream is copied from. In an output metadata specifier, all matching
758 streams are copied to.
760 @item @var{c}:@var{chapter_index}
761 per-chapter metadata. @var{chapter_index} is the zero-based chapter index.
763 @item @var{p}:@var{program_index}
764 per-program metadata. @var{program_index} is the zero-based program index.
765 @end table
766 If metadata specifier is omitted, it defaults to global.
768 By default, global metadata is copied from the first input file,
769 per-stream and per-chapter metadata is copied along with streams/chapters. These
770 default mappings are disabled by creating any mapping of the relevant type. A negative
771 file index can be used to create a dummy mapping that just disables automatic copying.
773 For example to copy metadata from the first stream of the input file to global metadata
774 of the output file:
775 @example
776 avconv -i in.ogg -map_metadata 0:s:0 out.mp3
777 @end example
779 To do the reverse, i.e. copy global metadata to all audio streams:
780 @example
781 avconv -i in.mkv -map_metadata:s:a 0:g out.mkv
782 @end example
783 Note that simple @code{0} would work as well in this example, since global
784 metadata is assumed by default.
786 @item -map_chapters @var{input_file_index} (@emph{output})
787 Copy chapters from input file with index @var{input_file_index} to the next
788 output file. If no chapter mapping is specified, then chapters are copied from
789 the first input file with at least one chapter. Use a negative file index to
790 disable any chapter copying.
791 @item -debug
792 Print specific debug info.
793 @item -benchmark (@emph{global})
794 Show benchmarking information at the end of an encode.
795 Shows CPU time used and maximum memory consumption.
796 Maximum memory consumption is not supported on all systems,
797 it will usually display as 0 if not supported.
798 @item -timelimit @var{duration} (@emph{global})
799 Exit after avconv has been running for @var{duration} seconds.
800 @item -dump (@emph{global})
801 Dump each input packet to stderr.
802 @item -hex (@emph{global})
803 When dumping packets, also dump the payload.
804 @item -re (@emph{input})
805 Read input at native frame rate. Mainly used to simulate a grab device
806 or live input stream (e.g. when reading from a file). Should not be used
807 with actual grab devices or live input streams (where it can cause packet
808 loss).
809 @item -vsync @var{parameter}
810 Video sync method.
812 @table @option
813 @item passthrough
814 Each frame is passed with its timestamp from the demuxer to the muxer.
815 @item cfr
816 Frames will be duplicated and dropped to achieve exactly the requested
817 constant framerate.
818 @item vfr
819 Frames are passed through with their timestamp or dropped so as to
820 prevent 2 frames from having the same timestamp.
821 @item auto
822 Chooses between 1 and 2 depending on muxer capabilities. This is the
823 default method.
824 @end table
826 With -map you can select from which stream the timestamps should be
827 taken. You can leave either video or audio unchanged and sync the
828 remaining stream(s) to the unchanged one.
830 @item -async @var{samples_per_second}
831 Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
832 the parameter is the maximum samples per second by which the audio is changed.
833 -async 1 is a special case where only the start of the audio stream is corrected
834 without any later correction.
835 This option has been deprecated. Use the @code{asyncts} audio filter instead.
836 @item -copyts
837 Copy timestamps from input to output.
838 @item -copytb
839 Copy input stream time base from input to output when stream copying.
840 @item -shortest (@emph{output})
841 Finish encoding when the shortest input stream ends.
842 @item -dts_delta_threshold
843 Timestamp discontinuity delta threshold.
844 @item -muxdelay @var{seconds} (@emph{input})
845 Set the maximum demux-decode delay.
846 @item -muxpreload @var{seconds} (@emph{input})
847 Set the initial demux-decode delay.
848 @item -streamid @var{output-stream-index}:@var{new-value} (@emph{output})
849 Assign a new stream-id value to an output stream. This option should be
850 specified prior to the output filename to which it applies.
851 For the situation where multiple output files exist, a streamid
852 may be reassigned to a different value.
854 For example, to set the stream 0 PID to 33 and the stream 1 PID to 36 for
855 an output mpegts file:
856 @example
857 avconv -i infile -streamid 0:33 -streamid 1:36 out.ts
858 @end example
860 @item -bsf[:@var{stream_specifier}] @var{bitstream_filters} (@emph{output,per-stream})
861 Set bitstream filters for matching streams. @var{bistream_filters} is
862 a comma-separated list of bitstream filters. Use the @code{-bsfs} option
863 to get the list of bitstream filters.
864 @example
865 avconv -i h264.mp4 -c:v copy -bsf:v h264_mp4toannexb -an out.h264
866 @end example
867 @example
868 avconv -i file.mov -an -vn -bsf:s mov2textsub -c:s copy -f rawvideo sub.txt
869 @end example
871 @item -tag[:@var{stream_specifier}] @var{codec_tag} (@emph{input/output,per-stream})
872 Force a tag/fourcc for matching streams.
874 @item -filter_complex @var{filtergraph} (@emph{global})
875 Define a complex filter graph, i.e. one with arbitrary number of inputs and/or
876 outputs. For simple graphs -- those with one input and one output of the same
877 type -- see the @option{-filter} options. @var{filtergraph} is a description of
878 the filter graph, as described in @ref{Filtergraph syntax}.
880 Input link labels must refer to input streams using the
881 @code{[file_index:stream_specifier]} syntax (i.e. the same as @option{-map}
882 uses). If @var{stream_specifier} matches multiple streams, the first one will be
883 used. An unlabeled input will be connected to the first unused input stream of
884 the matching type.
886 Output link labels are referred to with @option{-map}. Unlabeled outputs are
887 added to the first output file.
889 Note that with this option it is possible to use only lavfi sources without
890 normal input files.
892 For example, to overlay an image over video
893 @example
894 avconv -i video.mkv -i image.png -filter_complex '[0:v][1:v]overlay[out]' -map
895 '[out]' out.mkv
896 @end example
897 Here @code{[0:v]} refers to the first video stream in the first input file,
898 which is linked to the first (main) input of the overlay filter. Similarly the
899 first video stream in the second input is linked to the second (overlay) input
900 of overlay.
902 Assuming there is only one video stream in each input file, we can omit input
903 labels, so the above is equivalent to
904 @example
905 avconv -i video.mkv -i image.png -filter_complex 'overlay[out]' -map
906 '[out]' out.mkv
907 @end example
909 Furthermore we can omit the output label and the single output from the filter
910 graph will be added to the output file automatically, so we can simply write
911 @example
912 avconv -i video.mkv -i image.png -filter_complex 'overlay' out.mkv
913 @end example
915 To generate 5 seconds of pure red video using lavfi @code{color} source:
916 @example
917 avconv -filter_complex 'color=red' -t 5 out.mkv
918 @end example
920 @item -filter_complex_script @var{filename} (@emph{global})
921 This option is similar to @option{-filter_complex}, the only difference is that
922 its argument is the name of the file from which a complex filtergraph
923 description is to be read.
925 @item -accurate_seek (@emph{input})
926 This option enables or disables accurate seeking in input files with the
927 @option{-ss} option. It is enabled by default, so seeking is accurate when
928 transcoding. Use @option{-noaccurate_seek} to disable it, which may be useful
929 e.g. when copying some streams and transcoding the others.
931 @end table
932 @c man end OPTIONS
934 @chapter Tips
935 @c man begin TIPS
937 @itemize
938 @item
939 For streaming at very low bitrate application, use a low frame rate
940 and a small GOP size. This is especially true for RealVideo where
941 the Linux player does not seem to be very fast, so it can miss
942 frames. An example is:
944 @example
945 avconv -g 3 -r 3 -t 10 -b 50k -s qcif -f rv10 /tmp/b.rm
946 @end example
948 @item
949 The parameter 'q' which is displayed while encoding is the current
950 quantizer. The value 1 indicates that a very good quality could
951 be achieved. The value 31 indicates the worst quality. If q=31 appears
952 too often, it means that the encoder cannot compress enough to meet
953 your bitrate. You must either increase the bitrate, decrease the
954 frame rate or decrease the frame size.
956 @item
957 If your computer is not fast enough, you can speed up the
958 compression at the expense of the compression ratio. You can use
959 '-me zero' to speed up motion estimation, and '-g 0' to disable
960 motion estimation completely (you have only I-frames, which means it
961 is about as good as JPEG compression).
963 @item
964 To have very low audio bitrates, reduce the sampling frequency
965 (down to 22050 Hz for MPEG audio, 22050 or 11025 for AC-3).
967 @item
968 To have a constant quality (but a variable bitrate), use the option
969 '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
970 quality).
972 @end itemize
973 @c man end TIPS
975 @chapter Examples
976 @c man begin EXAMPLES
978 @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 Libav source tree for examples.
986 Preset files are specified with the @code{pre} option, this option takes a
987 preset name as input. Avconv searches for a file named @var{preset_name}.avpreset in
988 the directories @file{$AVCONV_DATADIR} (if set), and @file{$HOME/.avconv}, and in
989 the data directory defined at configuration time (usually @file{$PREFIX/share/avconv})
990 in that order. For example, if the argument is @code{libx264-max}, it will
991 search for the file @file{libx264-max.avpreset}.
993 @section Video and Audio grabbing
995 If you specify the input format and device then avconv can grab video
996 and audio directly.
998 @example
999 avconv -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
1000 @end example
1002 Note that you must activate the right video source and channel before
1003 launching avconv with any TV viewer such as
1004 @uref{http://linux.bytesex.org/xawtv/, xawtv} by Gerd Knorr. You also
1005 have to set the audio recording levels correctly with a
1006 standard mixer.
1008 @section X11 grabbing
1010 Grab the X11 display with avconv via
1012 @example
1013 avconv -f x11grab -s cif -r 25 -i :0.0 /tmp/out.mpg
1014 @end example
1016 0.0 is display.screen number of your X11 server, same as
1017 the DISPLAY environment variable.
1019 @example
1020 avconv -f x11grab -s cif -r 25 -i :0.0+10,20 /tmp/out.mpg
1021 @end example
1023 0.0 is display.screen number of your X11 server, same as the DISPLAY environment
1024 variable. 10 is the x-offset and 20 the y-offset for the grabbing.
1026 @section Video and Audio file format conversion
1028 Any supported file format and protocol can serve as input to avconv:
1030 Examples:
1031 @itemize
1032 @item
1033 You can use YUV files as input:
1035 @example
1036 avconv -i /tmp/test%d.Y /tmp/out.mpg
1037 @end example
1039 It will use the files:
1040 @example
1041 /tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
1042 /tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
1043 @end example
1045 The Y files use twice the resolution of the U and V files. They are
1046 raw files, without header. They can be generated by all decent video
1047 decoders. You must specify the size of the image with the @option{-s} option
1048 if avconv cannot guess it.
1050 @item
1051 You can input from a raw YUV420P file:
1053 @example
1054 avconv -i /tmp/test.yuv /tmp/out.avi
1055 @end example
1057 test.yuv is a file containing raw YUV planar data. Each frame is composed
1058 of the Y plane followed by the U and V planes at half vertical and
1059 horizontal resolution.
1061 @item
1062 You can output to a raw YUV420P file:
1064 @example
1065 avconv -i mydivx.avi hugefile.yuv
1066 @end example
1068 @item
1069 You can set several input files and output files:
1071 @example
1072 avconv -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
1073 @end example
1075 Converts the audio file a.wav and the raw YUV video file a.yuv
1076 to MPEG file a.mpg.
1078 @item
1079 You can also do audio and video conversions at the same time:
1081 @example
1082 avconv -i /tmp/a.wav -ar 22050 /tmp/a.mp2
1083 @end example
1085 Converts a.wav to MPEG audio at 22050 Hz sample rate.
1087 @item
1088 You can encode to several formats at the same time and define a
1089 mapping from input stream to output streams:
1091 @example
1092 avconv -i /tmp/a.wav -map 0:a -b 64k /tmp/a.mp2 -map 0:a -b 128k /tmp/b.mp2
1093 @end example
1095 Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
1096 file:index' specifies which input stream is used for each output
1097 stream, in the order of the definition of output streams.
1099 @item
1100 You can transcode decrypted VOBs:
1102 @example
1103 avconv -i snatch_1.vob -f avi -c:v mpeg4 -b:v 800k -g 300 -bf 2 -c:a libmp3lame -b:a 128k snatch.avi
1104 @end example
1106 This is a typical DVD ripping example; the input is a VOB file, the
1107 output an AVI file with MPEG-4 video and MP3 audio. Note that in this
1108 command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
1109 GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
1110 input video. Furthermore, the audio stream is MP3-encoded so you need
1111 to enable LAME support by passing @code{--enable-libmp3lame} to configure.
1112 The mapping is particularly useful for DVD transcoding
1113 to get the desired audio language.
1115 NOTE: To see the supported input formats, use @code{avconv -formats}.
1117 @item
1118 You can extract images from a video, or create a video from many images:
1120 For extracting images from a video:
1121 @example
1122 avconv -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg
1123 @end example
1125 This will extract one video frame per second from the video and will
1126 output them in files named @file{foo-001.jpeg}, @file{foo-002.jpeg},
1127 etc. Images will be rescaled to fit the new WxH values.
1129 If you want to extract just a limited number of frames, you can use the
1130 above command in combination with the -vframes or -t option, or in
1131 combination with -ss to start extracting from a certain point in time.
1133 For creating a video from many images:
1134 @example
1135 avconv -f image2 -i foo-%03d.jpeg -r 12 -s WxH foo.avi
1136 @end example
1138 The syntax @code{foo-%03d.jpeg} specifies to use a decimal number
1139 composed of three digits padded with zeroes to express the sequence
1140 number. It is the same syntax supported by the C printf function, but
1141 only formats accepting a normal integer are suitable.
1143 @item
1144 You can put many streams of the same type in the output:
1146 @example
1147 avconv -i test1.avi -i test2.avi -map 1:1 -map 1:0 -map 0:1 -map 0:0 -c copy -y test12.nut
1148 @end example
1150 The resulting output file @file{test12.nut} will contain the first four streams
1151 from the input files in reverse order.
1153 @item
1154 To force CBR video output:
1155 @example
1156 avconv -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v
1157 @end example
1159 @item
1160 The four options lmin, lmax, mblmin and mblmax use 'lambda' units,
1161 but you may use the QP2LAMBDA constant to easily convert from 'q' units:
1162 @example
1163 avconv -i src.ext -lmax 21*QP2LAMBDA dst.ext
1164 @end example
1166 @end itemize
1167 @c man end EXAMPLES
1169 @include eval.texi
1170 @include decoders.texi
1171 @include encoders.texi
1172 @include demuxers.texi
1173 @include muxers.texi
1174 @include indevs.texi
1175 @include outdevs.texi
1176 @include protocols.texi
1177 @include bitstream_filters.texi
1178 @include filters.texi
1179 @include metadata.texi
1181 @ignore
1183 @setfilename avconv
1184 @settitle avconv video converter
1186 @c man begin SEEALSO
1187 avplay(1), avprobe(1) and the Libav HTML documentation
1188 @c man end
1190 @c man begin AUTHORS
1191 The Libav developers
1192 @c man end
1194 @end ignore
1196 @bye