[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 -loop @var{number} (@emph{input})
257 Set number of times input stream shall be looped. Loop 0 means no loop,
258 loop -1 means infinite loop.
260 @item -c[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
261 @itemx -codec[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
262 Select an encoder (when used before an output file) or a decoder (when used
263 before an input file) for one or more streams. @var{codec} is the name of a
264 decoder/encoder or a special value @code{copy} (output only) to indicate that
265 the stream is not to be reencoded.
267 For example
268 @example
269 avconv -i INPUT -map 0 -c:v libx264 -c:a copy OUTPUT
270 @end example
271 encodes all video streams with libx264 and copies all audio streams.
273 For each stream, the last matching @code{c} option is applied, so
274 @example
275 avconv -i INPUT -map 0 -c copy -c:v:1 libx264 -c:a:137 libvorbis OUTPUT
276 @end example
277 will copy all the streams except the second video, which will be encoded with
278 libx264, and the 138th audio, which will be encoded with libvorbis.
280 @item -t @var{duration} (@emph{output})
281 Stop writing the output after its duration reaches @var{duration}.
282 @var{duration} may be a number in seconds, or in @code{hh:mm:ss[.xxx]} form.
284 @item -fs @var{limit_size} (@emph{output})
285 Set the file size limit.
287 @item -ss @var{position} (@emph{input/output})
288 When used as an input option (before @code{-i}), seeks in this input file to
289 @var{position}. Note the in most formats it is not possible to seek exactly, so
290 @command{avconv} will seek to the closest seek point before @var{position}.
291 When transcoding and @option{-accurate_seek} is enabled (the default), this
292 extra segment between the seek point and @var{position} will be decoded and
293 discarded. When doing stream copy or when @option{-noaccurate_seek} is used, it
294 will be preserved.
296 When used as an output option (before an output filename), decodes but discards
297 input until the timestamps reach @var{position}.
299 @var{position} may be either in seconds or in @code{hh:mm:ss[.xxx]} form.
301 @item -itsoffset @var{offset} (@emph{input})
302 Set the input time offset in seconds.
303 @code{[-]hh:mm:ss[.xxx]} syntax is also supported.
304 The offset is added to the timestamps of the input files.
305 Specifying a positive offset means that the corresponding
306 streams are delayed by @var{offset} seconds.
308 @item -metadata[:metadata_specifier] @var{key}=@var{value} (@emph{output,per-metadata})
309 Set a metadata key/value pair.
311 An optional @var{metadata_specifier} may be given to set metadata
312 on streams or chapters. See @code{-map_metadata} documentation for
313 details.
315 This option overrides metadata set with @code{-map_metadata}. It is
316 also possible to delete metadata by using an empty value.
318 For example, for setting the title in the output file:
319 @example
320 avconv -i in.avi -metadata title="my title" out.flv
321 @end example
323 To set the language of the first audio stream:
324 @example
325 avconv -i INPUT -metadata:s:a:0 language=eng OUTPUT
326 @end example
328 @item -target @var{type} (@emph{output})
329 Specify target file type (@code{vcd}, @code{svcd}, @code{dvd}, @code{dv},
330 @code{dv50}). @var{type} may be prefixed with @code{pal-}, @code{ntsc-} or
331 @code{film-} to use the corresponding standard. All the format options
332 (bitrate, codecs, buffer sizes) are then set automatically. You can just type:
334 @example
335 avconv -i myfile.avi -target vcd /tmp/vcd.mpg
336 @end example
338 Nevertheless you can specify additional options as long as you know
339 they do not conflict with the standard, as in:
341 @example
342 avconv -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
343 @end example
345 @item -dframes @var{number} (@emph{output})
346 Set the number of data frames to record. This is an alias for @code{-frames:d}.
348 @item -frames[:@var{stream_specifier}] @var{framecount} (@emph{output,per-stream})
349 Stop writing to the stream after @var{framecount} frames.
351 @item -q[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
352 @itemx -qscale[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
353 Use fixed quality scale (VBR). The meaning of @var{q} is
354 codec-dependent.
356 @item -filter[:@var{stream_specifier}] @var{filter_graph} (@emph{output,per-stream})
357 @var{filter_graph} is a description of the filter graph to apply to
358 the stream. Use @code{-filters} to show all the available filters
359 (including also sources and sinks).
361 See also the @option{-filter_complex} option if you want to create filter graphs
362 with multiple inputs and/or outputs.
364 @item -filter_script[:@var{stream_specifier}] @var{filename} (@emph{output,per-stream})
365 This option is similar to @option{-filter}, the only difference is that its
366 argument is the name of the file from which a filtergraph description is to be
367 read.
369 @item -pre[:@var{stream_specifier}] @var{preset_name} (@emph{output,per-stream})
370 Specify the preset for matching stream(s).
372 @item -stats (@emph{global})
373 Print encoding progress/statistics. On by default.
375 @item -attach @var{filename} (@emph{output})
376 Add an attachment to the output file. This is supported by a few formats
377 like Matroska for e.g. fonts used in rendering subtitles. Attachments
378 are implemented as a specific type of stream, so this option will add
379 a new stream to the file. It is then possible to use per-stream options
380 on this stream in the usual way. Attachment streams created with this
381 option will be created after all the other streams (i.e. those created
382 with @code{-map} or automatic mappings).
384 Note that for Matroska you also have to set the mimetype metadata tag:
385 @example
386 avconv -i INPUT -attach DejaVuSans.ttf -metadata:s:2 mimetype=application/x-truetype-font out.mkv
387 @end example
388 (assuming that the attachment stream will be third in the output file).
390 @item -dump_attachment[:@var{stream_specifier}] @var{filename} (@emph{input,per-stream})
391 Extract the matching attachment stream into a file named @var{filename}. If
392 @var{filename} is empty, then the value of the @code{filename} metadata tag
393 will be used.
395 E.g. to extract the first attachment to a file named 'out.ttf':
396 @example
397 avconv -dump_attachment:t:0 out.ttf INPUT
398 @end example
399 To extract all attachments to files determined by the @code{filename} tag:
400 @example
401 avconv -dump_attachment:t "" INPUT
402 @end example
404 Technical note -- attachments are implemented as codec extradata, so this
405 option can actually be used to extract extradata from any stream, not just
406 attachments.
408 @item -noautorotate
409 Disable automatically rotating video based on file metadata.
411 @end table
413 @section Video Options
415 @table @option
416 @item -vframes @var{number} (@emph{output})
417 Set the number of video frames to record. This is an alias for @code{-frames:v}.
418 @item -r[:@var{stream_specifier}] @var{fps} (@emph{input/output,per-stream})
419 Set frame rate (Hz value, fraction or abbreviation).
421 As an input option, ignore any timestamps stored in the file and instead
422 generate timestamps assuming constant frame rate @var{fps}.
424 As an output option, duplicate or drop input frames to achieve constant output
425 frame rate @var{fps} (note that this actually causes the @code{fps} filter to be
426 inserted to the end of the corresponding filtergraph).
428 @item -s[:@var{stream_specifier}] @var{size} (@emph{input/output,per-stream})
429 Set frame size.
431 As an input option, this is a shortcut for the @option{video_size} private
432 option, recognized by some demuxers for which the frame size is either not
433 stored in the file or is configurable -- e.g. raw video or video grabbers.
435 As an output option, this inserts the @code{scale} video filter to the
436 @emph{end} of the corresponding filtergraph. Please use the @code{scale} filter
437 directly to insert it at the beginning or some other place.
439 The format is @samp{wxh} (default - same as source). The following
440 abbreviations are recognized:
441 @table @samp
442 @item sqcif
443 128x96
444 @item qcif
445 176x144
446 @item cif
447 352x288
448 @item 4cif
449 704x576
450 @item 16cif
451 1408x1152
452 @item qqvga
453 160x120
454 @item qvga
455 320x240
456 @item vga
457 640x480
458 @item svga
459 800x600
460 @item xga
461 1024x768
462 @item uxga
463 1600x1200
464 @item qxga
465 2048x1536
466 @item sxga
467 1280x1024
468 @item qsxga
469 2560x2048
470 @item hsxga
471 5120x4096
472 @item wvga
473 852x480
474 @item wxga
475 1366x768
476 @item wsxga
477 1600x1024
478 @item wuxga
479 1920x1200
480 @item woxga
481 2560x1600
482 @item wqsxga
483 3200x2048
484 @item wquxga
485 3840x2400
486 @item whsxga
487 6400x4096
488 @item whuxga
489 7680x4800
490 @item cga
491 320x200
492 @item ega
493 640x350
494 @item hd480
495 852x480
496 @item hd720
497 1280x720
498 @item hd1080
499 1920x1080
500 @item 2kdci
501 2048x1080
502 @item 4kdci
503 4096x2160
504 @item uhd2160
505 3840x2160
506 @item uhd4320
507 7680x4320
508 @end table
510 @item -aspect[:@var{stream_specifier}] @var{aspect} (@emph{output,per-stream})
511 Set the video display aspect ratio specified by @var{aspect}.
513 @var{aspect} can be a floating point number string, or a string of the
514 form @var{num}:@var{den}, where @var{num} and @var{den} are the
515 numerator and denominator of the aspect ratio. For example "4:3",
516 "16:9", "1.3333", and "1.7777" are valid argument values.
518 @item -vn (@emph{output})
519 Disable video recording.
521 @item -vcodec @var{codec} (@emph{output})
522 Set the video codec. This is an alias for @code{-codec:v}.
524 @item -pass[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
525 Select the pass number (1 or 2). It is used to do two-pass
526 video encoding. The statistics of the video are recorded in the first
527 pass into a log file (see also the option -passlogfile),
528 and in the second pass that log file is used to generate the video
529 at the exact requested bitrate.
530 On pass 1, you may just deactivate audio and set output to null,
531 examples for Windows and Unix:
532 @example
533 avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y NUL
534 avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null
535 @end example
537 @item -passlogfile[:@var{stream_specifier}] @var{prefix} (@emph{output,per-stream})
538 Set two-pass log file name prefix to @var{prefix}, the default file name
539 prefix is ``av2pass''. The complete file name will be
540 @file{PREFIX-N.log}, where N is a number specific to the output
541 stream.
543 @item -vf @var{filter_graph} (@emph{output})
544 @var{filter_graph} is a description of the filter graph to apply to
545 the input video.
546 Use the option "-filters" to show all the available filters (including
547 also sources and sinks). This is an alias for @code{-filter:v}.
549 @end table
551 @section Advanced Video Options
553 @table @option
554 @item -pix_fmt[:@var{stream_specifier}] @var{format} (@emph{input/output,per-stream})
555 Set pixel format. Use @code{-pix_fmts} to show all the supported
556 pixel formats.
557 @item -sws_flags @var{flags} (@emph{input/output})
558 Set SwScaler flags.
559 @item -vdt @var{n}
560 Discard threshold.
562 @item -rc_override[:@var{stream_specifier}] @var{override} (@emph{output,per-stream})
563 rate control override for specific intervals
565 @item -vstats
566 Dump video coding statistics to @file{vstats_HHMMSS.log}.
567 @item -vstats_file @var{file}
568 Dump video coding statistics to @var{file}.
569 @item -top[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
570 top=1/bottom=0/auto=-1 field first
571 @item -dc @var{precision}
572 Intra_dc_precision.
573 @item -vtag @var{fourcc/tag} (@emph{output})
574 Force video tag/fourcc. This is an alias for @code{-tag:v}.
575 @item -qphist (@emph{global})
576 Show QP histogram.
577 @item -force_key_frames[:@var{stream_specifier}] @var{time}[,@var{time}...] (@emph{output,per-stream})
578 Force key frames at the specified timestamps, more precisely at the first
579 frames after each specified time.
580 This option can be useful to ensure that a seek point is present at a
581 chapter mark or any other designated place in the output file.
582 The timestamps must be specified in ascending order.
584 @item -copyinkf[:@var{stream_specifier}] (@emph{output,per-stream})
585 When doing stream copy, copy also non-key frames found at the
586 beginning.
588 @item -hwaccel[:@var{stream_specifier}] @var{hwaccel} (@emph{input,per-stream})
589 Use hardware acceleration to decode the matching stream(s). The allowed values
590 of @var{hwaccel} are:
591 @table @option
592 @item none
593 Do not use any hardware acceleration (the default).
595 @item auto
596 Automatically select the hardware acceleration method.
598 @item vda
599 Use Apple VDA hardware acceleration.
601 @item vdpau
602 Use VDPAU (Video Decode and Presentation API for Unix) hardware acceleration.
604 @item dxva2
605 Use DXVA2 (DirectX Video Acceleration) hardware acceleration.
607 @item qsv
608 Use the Intel QuickSync Video acceleration for video transcoding.
610 Unlike most other values, this option does not enable accelerated decoding (that
611 is used automatically whenever a qsv decoder is selected), but accelerated
612 transcoding, without copying the frames into the system memory.
614 For it to work, both the decoder and the encoder must support QSV acceleration
615 and no filters must be used.
616 @end table
618 This option has no effect if the selected hwaccel is not available or not
619 supported by the chosen decoder.
621 Note that most acceleration methods are intended for playback and will not be
622 faster than software decoding on modern CPUs. Additionally, @command{avconv}
623 will usually need to copy the decoded frames from the GPU memory into the system
624 memory, resulting in further performance loss. This option is thus mainly
625 useful for testing.
627 @item -hwaccel_device[:@var{stream_specifier}] @var{hwaccel_device} (@emph{input,per-stream})
628 Select a device to use for hardware acceleration.
630 This option only makes sense when the @option{-hwaccel} option is also
631 specified. Its exact meaning depends on the specific hardware acceleration
632 method chosen.
634 @table @option
635 @item vdpau
636 For VDPAU, this option specifies the X11 display/screen to use. If this option
637 is not specified, the value of the @var{DISPLAY} environment variable is used
639 @item dxva2
640 For DXVA2, this option should contain the number of the display adapter to use.
641 If this option is not specified, the default adapter is used.
643 @item qsv
644 For QSV, this option corresponds to the values of MFX_IMPL_* . Allowed values
645 are:
646 @table @option
647 @item auto
648 @item sw
649 @item hw
650 @item auto_any
651 @item hw_any
652 @item hw2
653 @item hw3
654 @item hw4
655 @end table
656 @end table
658 @item -hwaccels
659 List all hardware acceleration methods supported in this build of avconv.
661 @end table
663 @section Audio Options
665 @table @option
666 @item -aframes @var{number} (@emph{output})
667 Set the number of audio frames to record. This is an alias for @code{-frames:a}.
668 @item -ar[:@var{stream_specifier}] @var{freq} (@emph{input/output,per-stream})
669 Set the audio sampling frequency. For output streams it is set by
670 default to the frequency of the corresponding input stream. For input
671 streams this option only makes sense for audio grabbing devices and raw
672 demuxers and is mapped to the corresponding demuxer options.
673 @item -aq @var{q} (@emph{output})
674 Set the audio quality (codec-specific, VBR). This is an alias for -q:a.
675 @item -ac[:@var{stream_specifier}] @var{channels} (@emph{input/output,per-stream})
676 Set the number of audio channels. For output streams it is set by
677 default to the number of input audio channels. For input streams
678 this option only makes sense for audio grabbing devices and raw demuxers
679 and is mapped to the corresponding demuxer options.
680 @item -an (@emph{output})
681 Disable audio recording.
682 @item -acodec @var{codec} (@emph{input/output})
683 Set the audio codec. This is an alias for @code{-codec:a}.
684 @item -sample_fmt[:@var{stream_specifier}] @var{sample_fmt} (@emph{output,per-stream})
685 Set the audio sample format. Use @code{-sample_fmts} to get a list
686 of supported sample formats.
687 @item -af @var{filter_graph} (@emph{output})
688 @var{filter_graph} is a description of the filter graph to apply to
689 the input audio.
690 Use the option "-filters" to show all the available filters (including
691 also sources and sinks). This is an alias for @code{-filter:a}.
692 @end table
694 @section Advanced Audio options:
696 @table @option
697 @item -atag @var{fourcc/tag} (@emph{output})
698 Force audio tag/fourcc. This is an alias for @code{-tag:a}.
699 @end table
701 @section Subtitle options:
703 @table @option
704 @item -scodec @var{codec} (@emph{input/output})
705 Set the subtitle codec. This is an alias for @code{-codec:s}.
706 @item -sn (@emph{output})
707 Disable subtitle recording.
708 @end table
710 @section Advanced options
712 @table @option
713 @item -map [-]@var{input_file_id}[:@var{stream_specifier}][,@var{sync_file_id}[:@var{stream_specifier}]] | @var{[linklabel]} (@emph{output})
715 Designate one or more input streams as a source for the output file. Each input
716 stream is identified by the input file index @var{input_file_id} and
717 the input stream index @var{input_stream_id} within the input
718 file. Both indices start at 0. If specified,
719 @var{sync_file_id}:@var{stream_specifier} sets which input stream
720 is used as a presentation sync reference.
722 The first @code{-map} option on the command line specifies the
723 source for output stream 0, the second @code{-map} option specifies
724 the source for output stream 1, etc.
726 A @code{-} character before the stream identifier creates a "negative" mapping.
727 It disables matching streams from already created mappings.
729 An alternative @var{[linklabel]} form will map outputs from complex filter
730 graphs (see the @option{-filter_complex} option) to the output file.
731 @var{linklabel} must correspond to a defined output link label in the graph.
733 For example, to map ALL streams from the first input file to output
734 @example
735 avconv -i INPUT -map 0 output
736 @end example
738 For example, if you have two audio streams in the first input file,
739 these streams are identified by "0:0" and "0:1". You can use
740 @code{-map} to select which streams to place in an output file. For
741 example:
742 @example
743 avconv -i INPUT -map 0:1 out.wav
744 @end example
745 will map the input stream in @file{INPUT} identified by "0:1" to
746 the (single) output stream in @file{out.wav}.
748 For example, to select the stream with index 2 from input file
749 @file{a.mov} (specified by the identifier "0:2"), and stream with
750 index 6 from input @file{b.mov} (specified by the identifier "1:6"),
751 and copy them to the output file @file{out.mov}:
752 @example
753 avconv -i a.mov -i b.mov -c copy -map 0:2 -map 1:6 out.mov
754 @end example
756 To select all video and the third audio stream from an input file:
757 @example
758 avconv -i INPUT -map 0:v -map 0:a:2 OUTPUT
759 @end example
761 To map all the streams except the second audio, use negative mappings
762 @example
763 avconv -i INPUT -map 0 -map -0:a:1 OUTPUT
764 @end example
766 To pick the English audio stream:
767 @example
768 avconv -i INPUT -map 0:m:language:eng OUTPUT
769 @end example
771 Note that using this option disables the default mappings for this output file.
773 @item -map_metadata[:@var{metadata_spec_out}] @var{infile}[:@var{metadata_spec_in}] (@emph{output,per-metadata})
774 Set metadata information of the next output file from @var{infile}. Note that
775 those are file indices (zero-based), not filenames.
776 Optional @var{metadata_spec_in/out} parameters specify, which metadata to copy.
777 A metadata specifier can have the following forms:
778 @table @option
779 @item @var{g}
780 global metadata, i.e. metadata that applies to the whole file
782 @item @var{s}[:@var{stream_spec}]
783 per-stream metadata. @var{stream_spec} is a stream specifier as described
784 in the @ref{Stream specifiers} chapter. In an input metadata specifier, the first
785 matching stream is copied from. In an output metadata specifier, all matching
786 streams are copied to.
788 @item @var{c}:@var{chapter_index}
789 per-chapter metadata. @var{chapter_index} is the zero-based chapter index.
791 @item @var{p}:@var{program_index}
792 per-program metadata. @var{program_index} is the zero-based program index.
793 @end table
794 If metadata specifier is omitted, it defaults to global.
796 By default, global metadata is copied from the first input file,
797 per-stream and per-chapter metadata is copied along with streams/chapters. These
798 default mappings are disabled by creating any mapping of the relevant type. A negative
799 file index can be used to create a dummy mapping that just disables automatic copying.
801 For example to copy metadata from the first stream of the input file to global metadata
802 of the output file:
803 @example
804 avconv -i in.ogg -map_metadata 0:s:0 out.mp3
805 @end example
807 To do the reverse, i.e. copy global metadata to all audio streams:
808 @example
809 avconv -i in.mkv -map_metadata:s:a 0:g out.mkv
810 @end example
811 Note that simple @code{0} would work as well in this example, since global
812 metadata is assumed by default.
814 @item -map_chapters @var{input_file_index} (@emph{output})
815 Copy chapters from input file with index @var{input_file_index} to the next
816 output file. If no chapter mapping is specified, then chapters are copied from
817 the first input file with at least one chapter. Use a negative file index to
818 disable any chapter copying.
819 @item -debug
820 Print specific debug info.
821 @item -benchmark (@emph{global})
822 Show benchmarking information at the end of an encode.
823 Shows CPU time used and maximum memory consumption.
824 Maximum memory consumption is not supported on all systems,
825 it will usually display as 0 if not supported.
826 @item -timelimit @var{duration} (@emph{global})
827 Exit after avconv has been running for @var{duration} seconds.
828 @item -dump (@emph{global})
829 Dump each input packet to stderr.
830 @item -hex (@emph{global})
831 When dumping packets, also dump the payload.
832 @item -re (@emph{input})
833 Read input at native frame rate. Mainly used to simulate a grab device
834 or live input stream (e.g. when reading from a file). Should not be used
835 with actual grab devices or live input streams (where it can cause packet
836 loss).
837 @item -vsync @var{parameter}
838 Video sync method.
840 @table @option
841 @item passthrough
842 Each frame is passed with its timestamp from the demuxer to the muxer.
843 @item cfr
844 Frames will be duplicated and dropped to achieve exactly the requested
845 constant framerate.
846 @item vfr
847 Frames are passed through with their timestamp or dropped so as to
848 prevent 2 frames from having the same timestamp.
849 @item auto
850 Chooses between 1 and 2 depending on muxer capabilities. This is the
851 default method.
852 @end table
854 With -map you can select from which stream the timestamps should be
855 taken. You can leave either video or audio unchanged and sync the
856 remaining stream(s) to the unchanged one.
858 @item -async @var{samples_per_second}
859 Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
860 the parameter is the maximum samples per second by which the audio is changed.
861 -async 1 is a special case where only the start of the audio stream is corrected
862 without any later correction.
863 This option has been deprecated. Use the @code{asyncts} audio filter instead.
864 @item -copyts
865 Copy timestamps from input to output.
866 @item -copytb
867 Copy input stream time base from input to output when stream copying.
868 @item -shortest (@emph{output})
869 Finish encoding when the shortest input stream ends.
870 @item -dts_delta_threshold
871 Timestamp discontinuity delta threshold.
872 @item -muxdelay @var{seconds} (@emph{input})
873 Set the maximum demux-decode delay.
874 @item -muxpreload @var{seconds} (@emph{input})
875 Set the initial demux-decode delay.
876 @item -streamid @var{output-stream-index}:@var{new-value} (@emph{output})
877 Assign a new stream-id value to an output stream. This option should be
878 specified prior to the output filename to which it applies.
879 For the situation where multiple output files exist, a streamid
880 may be reassigned to a different value.
882 For example, to set the stream 0 PID to 33 and the stream 1 PID to 36 for
883 an output mpegts file:
884 @example
885 avconv -i infile -streamid 0:33 -streamid 1:36 out.ts
886 @end example
888 @item -bsf[:@var{stream_specifier}] @var{bitstream_filters} (@emph{output,per-stream})
889 Set bitstream filters for matching streams. @var{bitstream_filters} is
890 a comma-separated list of bitstream filters. Use the @code{-bsfs} option
891 to get the list of bitstream filters.
892 @example
893 avconv -i h264.mp4 -c:v copy -bsf:v h264_mp4toannexb -an out.h264
894 @end example
895 @example
896 avconv -i file.mov -an -vn -bsf:s mov2textsub -c:s copy -f rawvideo sub.txt
897 @end example
899 @item -tag[:@var{stream_specifier}] @var{codec_tag} (@emph{input/output,per-stream})
900 Force a tag/fourcc for matching streams.
902 @item -filter_complex @var{filtergraph} (@emph{global})
903 Define a complex filter graph, i.e. one with arbitrary number of inputs and/or
904 outputs. For simple graphs -- those with one input and one output of the same
905 type -- see the @option{-filter} options. @var{filtergraph} is a description of
906 the filter graph, as described in @ref{Filtergraph syntax}.
908 Input link labels must refer to input streams using the
909 @code{[file_index:stream_specifier]} syntax (i.e. the same as @option{-map}
910 uses). If @var{stream_specifier} matches multiple streams, the first one will be
911 used. An unlabeled input will be connected to the first unused input stream of
912 the matching type.
914 Output link labels are referred to with @option{-map}. Unlabeled outputs are
915 added to the first output file.
917 Note that with this option it is possible to use only lavfi sources without
918 normal input files.
920 For example, to overlay an image over video
921 @example
922 avconv -i video.mkv -i image.png -filter_complex '[0:v][1:v]overlay[out]' -map
923 '[out]' out.mkv
924 @end example
925 Here @code{[0:v]} refers to the first video stream in the first input file,
926 which is linked to the first (main) input of the overlay filter. Similarly the
927 first video stream in the second input is linked to the second (overlay) input
928 of overlay.
930 Assuming there is only one video stream in each input file, we can omit input
931 labels, so the above is equivalent to
932 @example
933 avconv -i video.mkv -i image.png -filter_complex 'overlay[out]' -map
934 '[out]' out.mkv
935 @end example
937 Furthermore we can omit the output label and the single output from the filter
938 graph will be added to the output file automatically, so we can simply write
939 @example
940 avconv -i video.mkv -i image.png -filter_complex 'overlay' out.mkv
941 @end example
943 To generate 5 seconds of pure red video using lavfi @code{color} source:
944 @example
945 avconv -filter_complex 'color=red' -t 5 out.mkv
946 @end example
948 @item -filter_complex_script @var{filename} (@emph{global})
949 This option is similar to @option{-filter_complex}, the only difference is that
950 its argument is the name of the file from which a complex filtergraph
951 description is to be read.
953 @item -accurate_seek (@emph{input})
954 This option enables or disables accurate seeking in input files with the
955 @option{-ss} option. It is enabled by default, so seeking is accurate when
956 transcoding. Use @option{-noaccurate_seek} to disable it, which may be useful
957 e.g. when copying some streams and transcoding the others.
959 @item -max_muxing_queue_size @var{packets} (@emph{output,per-stream})
960 When transcoding audio and/or video streams, avconv will not begin writing into
961 the output until it has one packet for each such stream. While waiting for that
962 to happen, packets for other streams are buffered. This option sets the size of
963 this buffer, in packets, for the matching output stream.
965 The default value of this option should be high enough for most uses, so only
966 touch this option if you are sure that you need it.
968 @end table
969 @c man end OPTIONS
971 @chapter Tips
972 @c man begin TIPS
974 @itemize
975 @item
976 For streaming at very low bitrate application, use a low frame rate
977 and a small GOP size. This is especially true for RealVideo where
978 the Linux player does not seem to be very fast, so it can miss
979 frames. An example is:
981 @example
982 avconv -g 3 -r 3 -t 10 -b 50k -s qcif -f rv10 /tmp/b.rm
983 @end example
985 @item
986 The parameter 'q' which is displayed while encoding is the current
987 quantizer. The value 1 indicates that a very good quality could
988 be achieved. The value 31 indicates the worst quality. If q=31 appears
989 too often, it means that the encoder cannot compress enough to meet
990 your bitrate. You must either increase the bitrate, decrease the
991 frame rate or decrease the frame size.
993 @item
994 If your computer is not fast enough, you can speed up the
995 compression at the expense of the compression ratio. You can use
996 '-me zero' to speed up motion estimation, and '-g 0' to disable
997 motion estimation completely (you have only I-frames, which means it
998 is about as good as JPEG compression).
1000 @item
1001 To have very low audio bitrates, reduce the sampling frequency
1002 (down to 22050 Hz for MPEG audio, 22050 or 11025 for AC-3).
1004 @item
1005 To have a constant quality (but a variable bitrate), use the option
1006 '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
1007 quality).
1009 @end itemize
1010 @c man end TIPS
1012 @chapter Examples
1013 @c man begin EXAMPLES
1015 @section Preset files
1017 A preset file contains a sequence of @var{option=value} pairs, one for
1018 each line, specifying a sequence of options which can be specified also on
1019 the command line. Lines starting with the hash ('#') character are ignored and
1020 are used to provide comments. Empty lines are also ignored. Check the
1021 @file{presets} directory in the Libav source tree for examples.
1023 Preset files are specified with the @code{pre} option, this option takes a
1024 preset name as input. Avconv searches for a file named @var{preset_name}.avpreset in
1025 the directories @file{$AVCONV_DATADIR} (if set), and @file{$HOME/.avconv}, and in
1026 the data directory defined at configuration time (usually @file{$PREFIX/share/avconv})
1027 in that order. For example, if the argument is @code{libx264-max}, it will
1028 search for the file @file{libx264-max.avpreset}.
1030 @section Video and Audio grabbing
1032 If you specify the input format and device then avconv can grab video
1033 and audio directly.
1035 @example
1036 avconv -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
1037 @end example
1039 Note that you must activate the right video source and channel before
1040 launching avconv with any TV viewer such as
1041 @uref{http://linux.bytesex.org/xawtv/, xawtv} by Gerd Knorr. You also
1042 have to set the audio recording levels correctly with a
1043 standard mixer.
1045 @section X11 grabbing
1047 Grab the X11 display with avconv via
1049 @example
1050 avconv -f x11grab -s cif -r 25 -i :0.0 /tmp/out.mpg
1051 @end example
1053 0.0 is display.screen number of your X11 server, same as
1054 the DISPLAY environment variable.
1056 @example
1057 avconv -f x11grab -s cif -r 25 -i :0.0+10,20 /tmp/out.mpg
1058 @end example
1060 0.0 is display.screen number of your X11 server, same as the DISPLAY environment
1061 variable. 10 is the x-offset and 20 the y-offset for the grabbing.
1063 @section Video and Audio file format conversion
1065 Any supported file format and protocol can serve as input to avconv:
1067 Examples:
1068 @itemize
1069 @item
1070 You can use YUV files as input:
1072 @example
1073 avconv -i /tmp/test%d.Y /tmp/out.mpg
1074 @end example
1076 It will use the files:
1077 @example
1078 /tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
1079 /tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
1080 @end example
1082 The Y files use twice the resolution of the U and V files. They are
1083 raw files, without header. They can be generated by all decent video
1084 decoders. You must specify the size of the image with the @option{-s} option
1085 if avconv cannot guess it.
1087 @item
1088 You can input from a raw YUV420P file:
1090 @example
1091 avconv -i /tmp/test.yuv /tmp/out.avi
1092 @end example
1094 test.yuv is a file containing raw YUV planar data. Each frame is composed
1095 of the Y plane followed by the U and V planes at half vertical and
1096 horizontal resolution.
1098 @item
1099 You can output to a raw YUV420P file:
1101 @example
1102 avconv -i mydivx.avi hugefile.yuv
1103 @end example
1105 @item
1106 You can set several input files and output files:
1108 @example
1109 avconv -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
1110 @end example
1112 Converts the audio file a.wav and the raw YUV video file a.yuv
1113 to MPEG file a.mpg.
1115 @item
1116 You can also do audio and video conversions at the same time:
1118 @example
1119 avconv -i /tmp/a.wav -ar 22050 /tmp/a.mp2
1120 @end example
1122 Converts a.wav to MPEG audio at 22050 Hz sample rate.
1124 @item
1125 You can encode to several formats at the same time and define a
1126 mapping from input stream to output streams:
1128 @example
1129 avconv -i /tmp/a.wav -map 0:a -b 64k /tmp/a.mp2 -map 0:a -b 128k /tmp/b.mp2
1130 @end example
1132 Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
1133 file:index' specifies which input stream is used for each output
1134 stream, in the order of the definition of output streams.
1136 @item
1137 You can transcode decrypted VOBs:
1139 @example
1140 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
1141 @end example
1143 This is a typical DVD ripping example; the input is a VOB file, the
1144 output an AVI file with MPEG-4 video and MP3 audio. Note that in this
1145 command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
1146 GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
1147 input video. Furthermore, the audio stream is MP3-encoded so you need
1148 to enable LAME support by passing @code{--enable-libmp3lame} to configure.
1149 The mapping is particularly useful for DVD transcoding
1150 to get the desired audio language.
1152 NOTE: To see the supported input formats, use @code{avconv -formats}.
1154 @item
1155 You can extract images from a video, or create a video from many images:
1157 For extracting images from a video:
1158 @example
1159 avconv -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg
1160 @end example
1162 This will extract one video frame per second from the video and will
1163 output them in files named @file{foo-001.jpeg}, @file{foo-002.jpeg},
1164 etc. Images will be rescaled to fit the new WxH values.
1166 If you want to extract just a limited number of frames, you can use the
1167 above command in combination with the -vframes or -t option, or in
1168 combination with -ss to start extracting from a certain point in time.
1170 For creating a video from many images:
1171 @example
1172 avconv -f image2 -i foo-%03d.jpeg -r 12 -s WxH foo.avi
1173 @end example
1175 The syntax @code{foo-%03d.jpeg} specifies to use a decimal number
1176 composed of three digits padded with zeroes to express the sequence
1177 number. It is the same syntax supported by the C printf function, but
1178 only formats accepting a normal integer are suitable.
1180 @item
1181 You can put many streams of the same type in the output:
1183 @example
1184 avconv -i test1.avi -i test2.avi -map 1:1 -map 1:0 -map 0:1 -map 0:0 -c copy -y test12.nut
1185 @end example
1187 The resulting output file @file{test12.nut} will contain the first four streams
1188 from the input files in reverse order.
1190 @item
1191 To force CBR video output:
1192 @example
1193 avconv -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v
1194 @end example
1196 @item
1197 The four options lmin, lmax, mblmin and mblmax use 'lambda' units,
1198 but you may use the QP2LAMBDA constant to easily convert from 'q' units:
1199 @example
1200 avconv -i src.ext -lmax 21*QP2LAMBDA dst.ext
1201 @end example
1203 @end itemize
1204 @c man end EXAMPLES
1206 @include eval.texi
1207 @include decoders.texi
1208 @include encoders.texi
1209 @include demuxers.texi
1210 @include muxers.texi
1211 @include indevs.texi
1212 @include outdevs.texi
1213 @include protocols.texi
1214 @include bitstream_filters.texi
1215 @include filters.texi
1216 @include metadata.texi
1218 @ignore
1220 @setfilename avconv
1221 @settitle avconv video converter
1223 @c man begin SEEALSO
1224 avplay(1), avprobe(1) and the Libav HTML documentation
1225 @c man end
1227 @c man begin AUTHORS
1228 The Libav developers
1229 @c man end
1231 @end ignore
1233 @bye