[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 @end table
406 @section Video Options
408 @table @option
409 @item -vframes @var{number} (@emph{output})
410 Set the number of video frames to record. This is an alias for @code{-frames:v}.
411 @item -r[:@var{stream_specifier}] @var{fps} (@emph{input/output,per-stream})
412 Set frame rate (Hz value, fraction or abbreviation).
414 As an input option, ignore any timestamps stored in the file and instead
415 generate timestamps assuming constant frame rate @var{fps}.
417 As an output option, duplicate or drop input frames to achieve constant output
418 frame rate @var{fps} (note that this actually causes the @code{fps} filter to be
419 inserted to the end of the corresponding filtergraph).
421 @item -s[:@var{stream_specifier}] @var{size} (@emph{input/output,per-stream})
422 Set frame size.
424 As an input option, this is a shortcut for the @option{video_size} private
425 option, recognized by some demuxers for which the frame size is either not
426 stored in the file or is configurable -- e.g. raw video or video grabbers.
428 As an output option, this inserts the @code{scale} video filter to the
429 @emph{end} of the corresponding filtergraph. Please use the @code{scale} filter
430 directly to insert it at the beginning or some other place.
432 The format is @samp{wxh} (default - same as source). The following
433 abbreviations are recognized:
434 @table @samp
435 @item sqcif
436 128x96
437 @item qcif
438 176x144
439 @item cif
440 352x288
441 @item 4cif
442 704x576
443 @item 16cif
444 1408x1152
445 @item qqvga
446 160x120
447 @item qvga
448 320x240
449 @item vga
450 640x480
451 @item svga
452 800x600
453 @item xga
454 1024x768
455 @item uxga
456 1600x1200
457 @item qxga
458 2048x1536
459 @item sxga
460 1280x1024
461 @item qsxga
462 2560x2048
463 @item hsxga
464 5120x4096
465 @item wvga
466 852x480
467 @item wxga
468 1366x768
469 @item wsxga
470 1600x1024
471 @item wuxga
472 1920x1200
473 @item woxga
474 2560x1600
475 @item wqsxga
476 3200x2048
477 @item wquxga
478 3840x2400
479 @item whsxga
480 6400x4096
481 @item whuxga
482 7680x4800
483 @item cga
484 320x200
485 @item ega
486 640x350
487 @item hd480
488 852x480
489 @item hd720
490 1280x720
491 @item hd1080
492 1920x1080
493 @end table
495 @item -aspect[:@var{stream_specifier}] @var{aspect} (@emph{output,per-stream})
496 Set the video display aspect ratio specified by @var{aspect}.
498 @var{aspect} can be a floating point number string, or a string of the
499 form @var{num}:@var{den}, where @var{num} and @var{den} are the
500 numerator and denominator of the aspect ratio. For example "4:3",
501 "16:9", "1.3333", and "1.7777" are valid argument values.
503 @item -vn (@emph{output})
504 Disable video recording.
506 @item -vcodec @var{codec} (@emph{output})
507 Set the video codec. This is an alias for @code{-codec:v}.
509 @item -pass[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
510 Select the pass number (1 or 2). It is used to do two-pass
511 video encoding. The statistics of the video are recorded in the first
512 pass into a log file (see also the option -passlogfile),
513 and in the second pass that log file is used to generate the video
514 at the exact requested bitrate.
515 On pass 1, you may just deactivate audio and set output to null,
516 examples for Windows and Unix:
517 @example
518 avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y NUL
519 avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null
520 @end example
522 @item -passlogfile[:@var{stream_specifier}] @var{prefix} (@emph{output,per-stream})
523 Set two-pass log file name prefix to @var{prefix}, the default file name
524 prefix is ``av2pass''. The complete file name will be
525 @file{PREFIX-N.log}, where N is a number specific to the output
526 stream.
528 @item -vf @var{filter_graph} (@emph{output})
529 @var{filter_graph} is a description of the filter graph to apply to
530 the input video.
531 Use the option "-filters" to show all the available filters (including
532 also sources and sinks). This is an alias for @code{-filter:v}.
534 @end table
536 @section Advanced Video Options
538 @table @option
539 @item -pix_fmt[:@var{stream_specifier}] @var{format} (@emph{input/output,per-stream})
540 Set pixel format. Use @code{-pix_fmts} to show all the supported
541 pixel formats.
542 @item -sws_flags @var{flags} (@emph{input/output})
543 Set SwScaler flags.
544 @item -vdt @var{n}
545 Discard threshold.
547 @item -rc_override[:@var{stream_specifier}] @var{override} (@emph{output,per-stream})
548 rate control override for specific intervals
550 @item -vstats
551 Dump video coding statistics to @file{vstats_HHMMSS.log}.
552 @item -vstats_file @var{file}
553 Dump video coding statistics to @var{file}.
554 @item -top[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
555 top=1/bottom=0/auto=-1 field first
556 @item -dc @var{precision}
557 Intra_dc_precision.
558 @item -vtag @var{fourcc/tag} (@emph{output})
559 Force video tag/fourcc. This is an alias for @code{-tag:v}.
560 @item -qphist (@emph{global})
561 Show QP histogram.
562 @item -force_key_frames[:@var{stream_specifier}] @var{time}[,@var{time}...] (@emph{output,per-stream})
563 Force key frames at the specified timestamps, more precisely at the first
564 frames after each specified time.
565 This option can be useful to ensure that a seek point is present at a
566 chapter mark or any other designated place in the output file.
567 The timestamps must be specified in ascending order.
569 @item -copyinkf[:@var{stream_specifier}] (@emph{output,per-stream})
570 When doing stream copy, copy also non-key frames found at the
571 beginning.
573 @item -hwaccel[:@var{stream_specifier}] @var{hwaccel} (@emph{input,per-stream})
574 Use hardware acceleration to decode the matching stream(s). The allowed values
575 of @var{hwaccel} are:
576 @table @option
577 @item none
578 Do not use any hardware acceleration (the default).
580 @item auto
581 Automatically select the hardware acceleration method.
583 @item vda
584 Use Apple VDA hardware acceleration.
586 @item vdpau
587 Use VDPAU (Video Decode and Presentation API for Unix) hardware acceleration.
589 @item dxva2
590 Use DXVA2 (DirectX Video Acceleration) hardware acceleration.
591 @end table
593 This option has no effect if the selected hwaccel is not available or not
594 supported by the chosen decoder.
596 Note that most acceleration methods are intended for playback and will not be
597 faster than software decoding on modern CPUs. Additionally, @command{avconv}
598 will usually need to copy the decoded frames from the GPU memory into the system
599 memory, resulting in further performance loss. This option is thus mainly
600 useful for testing.
602 @item -hwaccel_device[:@var{stream_specifier}] @var{hwaccel_device} (@emph{input,per-stream})
603 Select a device to use for hardware acceleration.
605 This option only makes sense when the @option{-hwaccel} option is also
606 specified. Its exact meaning depends on the specific hardware acceleration
607 method chosen.
609 @table @option
610 @item vdpau
611 For VDPAU, this option specifies the X11 display/screen to use. If this option
612 is not specified, the value of the @var{DISPLAY} environment variable is used
614 @item dxva2
615 For DXVA2, this option should contain the number of the display adapter to use.
616 If this option is not specified, the default adapter is used.
617 @end table
618 @end table
620 @section Audio Options
622 @table @option
623 @item -aframes @var{number} (@emph{output})
624 Set the number of audio frames to record. This is an alias for @code{-frames:a}.
625 @item -ar[:@var{stream_specifier}] @var{freq} (@emph{input/output,per-stream})
626 Set the audio sampling frequency. For output streams it is set by
627 default to the frequency of the corresponding input stream. For input
628 streams this option only makes sense for audio grabbing devices and raw
629 demuxers and is mapped to the corresponding demuxer options.
630 @item -aq @var{q} (@emph{output})
631 Set the audio quality (codec-specific, VBR). This is an alias for -q:a.
632 @item -ac[:@var{stream_specifier}] @var{channels} (@emph{input/output,per-stream})
633 Set the number of audio channels. For output streams it is set by
634 default to the number of input audio channels. For input streams
635 this option only makes sense for audio grabbing devices and raw demuxers
636 and is mapped to the corresponding demuxer options.
637 @item -an (@emph{output})
638 Disable audio recording.
639 @item -acodec @var{codec} (@emph{input/output})
640 Set the audio codec. This is an alias for @code{-codec:a}.
641 @item -sample_fmt[:@var{stream_specifier}] @var{sample_fmt} (@emph{output,per-stream})
642 Set the audio sample format. Use @code{-sample_fmts} to get a list
643 of supported sample formats.
644 @item -af @var{filter_graph} (@emph{output})
645 @var{filter_graph} is a description of the filter graph to apply to
646 the input audio.
647 Use the option "-filters" to show all the available filters (including
648 also sources and sinks). This is an alias for @code{-filter:a}.
649 @end table
651 @section Advanced Audio options:
653 @table @option
654 @item -atag @var{fourcc/tag} (@emph{output})
655 Force audio tag/fourcc. This is an alias for @code{-tag:a}.
656 @end table
658 @section Subtitle options:
660 @table @option
661 @item -scodec @var{codec} (@emph{input/output})
662 Set the subtitle codec. This is an alias for @code{-codec:s}.
663 @item -sn (@emph{output})
664 Disable subtitle recording.
665 @end table
667 @section Advanced options
669 @table @option
670 @item -map [-]@var{input_file_id}[:@var{stream_specifier}][,@var{sync_file_id}[:@var{stream_specifier}]] | @var{[linklabel]} (@emph{output})
672 Designate one or more input streams as a source for the output file. Each input
673 stream is identified by the input file index @var{input_file_id} and
674 the input stream index @var{input_stream_id} within the input
675 file. Both indices start at 0. If specified,
676 @var{sync_file_id}:@var{stream_specifier} sets which input stream
677 is used as a presentation sync reference.
679 The first @code{-map} option on the command line specifies the
680 source for output stream 0, the second @code{-map} option specifies
681 the source for output stream 1, etc.
683 A @code{-} character before the stream identifier creates a "negative" mapping.
684 It disables matching streams from already created mappings.
686 An alternative @var{[linklabel]} form will map outputs from complex filter
687 graphs (see the @option{-filter_complex} option) to the output file.
688 @var{linklabel} must correspond to a defined output link label in the graph.
690 For example, to map ALL streams from the first input file to output
691 @example
692 avconv -i INPUT -map 0 output
693 @end example
695 For example, if you have two audio streams in the first input file,
696 these streams are identified by "0:0" and "0:1". You can use
697 @code{-map} to select which streams to place in an output file. For
698 example:
699 @example
700 avconv -i INPUT -map 0:1 out.wav
701 @end example
702 will map the input stream in @file{INPUT} identified by "0:1" to
703 the (single) output stream in @file{out.wav}.
705 For example, to select the stream with index 2 from input file
706 @file{a.mov} (specified by the identifier "0:2"), and stream with
707 index 6 from input @file{b.mov} (specified by the identifier "1:6"),
708 and copy them to the output file @file{out.mov}:
709 @example
710 avconv -i a.mov -i b.mov -c copy -map 0:2 -map 1:6 out.mov
711 @end example
713 To select all video and the third audio stream from an input file:
714 @example
715 avconv -i INPUT -map 0:v -map 0:a:2 OUTPUT
716 @end example
718 To map all the streams except the second audio, use negative mappings
719 @example
720 avconv -i INPUT -map 0 -map -0:a:1 OUTPUT
721 @end example
723 To pick the English audio stream:
724 @example
725 avconv -i INPUT -map 0:m:language:eng OUTPUT
726 @end example
728 Note that using this option disables the default mappings for this output file.
730 @item -map_metadata[:@var{metadata_spec_out}] @var{infile}[:@var{metadata_spec_in}] (@emph{output,per-metadata})
731 Set metadata information of the next output file from @var{infile}. Note that
732 those are file indices (zero-based), not filenames.
733 Optional @var{metadata_spec_in/out} parameters specify, which metadata to copy.
734 A metadata specifier can have the following forms:
735 @table @option
736 @item @var{g}
737 global metadata, i.e. metadata that applies to the whole file
739 @item @var{s}[:@var{stream_spec}]
740 per-stream metadata. @var{stream_spec} is a stream specifier as described
741 in the @ref{Stream specifiers} chapter. In an input metadata specifier, the first
742 matching stream is copied from. In an output metadata specifier, all matching
743 streams are copied to.
745 @item @var{c}:@var{chapter_index}
746 per-chapter metadata. @var{chapter_index} is the zero-based chapter index.
748 @item @var{p}:@var{program_index}
749 per-program metadata. @var{program_index} is the zero-based program index.
750 @end table
751 If metadata specifier is omitted, it defaults to global.
753 By default, global metadata is copied from the first input file,
754 per-stream and per-chapter metadata is copied along with streams/chapters. These
755 default mappings are disabled by creating any mapping of the relevant type. A negative
756 file index can be used to create a dummy mapping that just disables automatic copying.
758 For example to copy metadata from the first stream of the input file to global metadata
759 of the output file:
760 @example
761 avconv -i in.ogg -map_metadata 0:s:0 out.mp3
762 @end example
764 To do the reverse, i.e. copy global metadata to all audio streams:
765 @example
766 avconv -i in.mkv -map_metadata:s:a 0:g out.mkv
767 @end example
768 Note that simple @code{0} would work as well in this example, since global
769 metadata is assumed by default.
771 @item -map_chapters @var{input_file_index} (@emph{output})
772 Copy chapters from input file with index @var{input_file_index} to the next
773 output file. If no chapter mapping is specified, then chapters are copied from
774 the first input file with at least one chapter. Use a negative file index to
775 disable any chapter copying.
776 @item -debug
777 Print specific debug info.
778 @item -benchmark (@emph{global})
779 Show benchmarking information at the end of an encode.
780 Shows CPU time used and maximum memory consumption.
781 Maximum memory consumption is not supported on all systems,
782 it will usually display as 0 if not supported.
783 @item -timelimit @var{duration} (@emph{global})
784 Exit after avconv has been running for @var{duration} seconds.
785 @item -dump (@emph{global})
786 Dump each input packet to stderr.
787 @item -hex (@emph{global})
788 When dumping packets, also dump the payload.
789 @item -re (@emph{input})
790 Read input at native frame rate. Mainly used to simulate a grab device
791 or live input stream (e.g. when reading from a file). Should not be used
792 with actual grab devices or live input streams (where it can cause packet
793 loss).
794 @item -vsync @var{parameter}
795 Video sync method.
797 @table @option
798 @item passthrough
799 Each frame is passed with its timestamp from the demuxer to the muxer.
800 @item cfr
801 Frames will be duplicated and dropped to achieve exactly the requested
802 constant framerate.
803 @item vfr
804 Frames are passed through with their timestamp or dropped so as to
805 prevent 2 frames from having the same timestamp.
806 @item auto
807 Chooses between 1 and 2 depending on muxer capabilities. This is the
808 default method.
809 @end table
811 With -map you can select from which stream the timestamps should be
812 taken. You can leave either video or audio unchanged and sync the
813 remaining stream(s) to the unchanged one.
815 @item -async @var{samples_per_second}
816 Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
817 the parameter is the maximum samples per second by which the audio is changed.
818 -async 1 is a special case where only the start of the audio stream is corrected
819 without any later correction.
820 This option has been deprecated. Use the @code{asyncts} audio filter instead.
821 @item -copyts
822 Copy timestamps from input to output.
823 @item -copytb
824 Copy input stream time base from input to output when stream copying.
825 @item -shortest (@emph{output})
826 Finish encoding when the shortest input stream ends.
827 @item -dts_delta_threshold
828 Timestamp discontinuity delta threshold.
829 @item -muxdelay @var{seconds} (@emph{input})
830 Set the maximum demux-decode delay.
831 @item -muxpreload @var{seconds} (@emph{input})
832 Set the initial demux-decode delay.
833 @item -streamid @var{output-stream-index}:@var{new-value} (@emph{output})
834 Assign a new stream-id value to an output stream. This option should be
835 specified prior to the output filename to which it applies.
836 For the situation where multiple output files exist, a streamid
837 may be reassigned to a different value.
839 For example, to set the stream 0 PID to 33 and the stream 1 PID to 36 for
840 an output mpegts file:
841 @example
842 avconv -i infile -streamid 0:33 -streamid 1:36 out.ts
843 @end example
845 @item -bsf[:@var{stream_specifier}] @var{bitstream_filters} (@emph{output,per-stream})
846 Set bitstream filters for matching streams. @var{bistream_filters} is
847 a comma-separated list of bitstream filters. Use the @code{-bsfs} option
848 to get the list of bitstream filters.
849 @example
850 avconv -i h264.mp4 -c:v copy -bsf:v h264_mp4toannexb -an out.h264
851 @end example
852 @example
853 avconv -i file.mov -an -vn -bsf:s mov2textsub -c:s copy -f rawvideo sub.txt
854 @end example
856 @item -tag[:@var{stream_specifier}] @var{codec_tag} (@emph{input/output,per-stream})
857 Force a tag/fourcc for matching streams.
859 @item -filter_complex @var{filtergraph} (@emph{global})
860 Define a complex filter graph, i.e. one with arbitrary number of inputs and/or
861 outputs. For simple graphs -- those with one input and one output of the same
862 type -- see the @option{-filter} options. @var{filtergraph} is a description of
863 the filter graph, as described in @ref{Filtergraph syntax}.
865 Input link labels must refer to input streams using the
866 @code{[file_index:stream_specifier]} syntax (i.e. the same as @option{-map}
867 uses). If @var{stream_specifier} matches multiple streams, the first one will be
868 used. An unlabeled input will be connected to the first unused input stream of
869 the matching type.
871 Output link labels are referred to with @option{-map}. Unlabeled outputs are
872 added to the first output file.
874 Note that with this option it is possible to use only lavfi sources without
875 normal input files.
877 For example, to overlay an image over video
878 @example
879 avconv -i video.mkv -i image.png -filter_complex '[0:v][1:v]overlay[out]' -map
880 '[out]' out.mkv
881 @end example
882 Here @code{[0:v]} refers to the first video stream in the first input file,
883 which is linked to the first (main) input of the overlay filter. Similarly the
884 first video stream in the second input is linked to the second (overlay) input
885 of overlay.
887 Assuming there is only one video stream in each input file, we can omit input
888 labels, so the above is equivalent to
889 @example
890 avconv -i video.mkv -i image.png -filter_complex 'overlay[out]' -map
891 '[out]' out.mkv
892 @end example
894 Furthermore we can omit the output label and the single output from the filter
895 graph will be added to the output file automatically, so we can simply write
896 @example
897 avconv -i video.mkv -i image.png -filter_complex 'overlay' out.mkv
898 @end example
900 To generate 5 seconds of pure red video using lavfi @code{color} source:
901 @example
902 avconv -filter_complex 'color=red' -t 5 out.mkv
903 @end example
905 @item -filter_complex_script @var{filename} (@emph{global})
906 This option is similar to @option{-filter_complex}, the only difference is that
907 its argument is the name of the file from which a complex filtergraph
908 description is to be read.
910 @item -accurate_seek (@emph{input})
911 This option enables or disables accurate seeking in input files with the
912 @option{-ss} option. It is enabled by default, so seeking is accurate when
913 transcoding. Use @option{-noaccurate_seek} to disable it, which may be useful
914 e.g. when copying some streams and transcoding the others.
916 @end table
917 @c man end OPTIONS
919 @chapter Tips
920 @c man begin TIPS
922 @itemize
923 @item
924 For streaming at very low bitrate application, use a low frame rate
925 and a small GOP size. This is especially true for RealVideo where
926 the Linux player does not seem to be very fast, so it can miss
927 frames. An example is:
929 @example
930 avconv -g 3 -r 3 -t 10 -b 50k -s qcif -f rv10 /tmp/b.rm
931 @end example
933 @item
934 The parameter 'q' which is displayed while encoding is the current
935 quantizer. The value 1 indicates that a very good quality could
936 be achieved. The value 31 indicates the worst quality. If q=31 appears
937 too often, it means that the encoder cannot compress enough to meet
938 your bitrate. You must either increase the bitrate, decrease the
939 frame rate or decrease the frame size.
941 @item
942 If your computer is not fast enough, you can speed up the
943 compression at the expense of the compression ratio. You can use
944 '-me zero' to speed up motion estimation, and '-g 0' to disable
945 motion estimation completely (you have only I-frames, which means it
946 is about as good as JPEG compression).
948 @item
949 To have very low audio bitrates, reduce the sampling frequency
950 (down to 22050 Hz for MPEG audio, 22050 or 11025 for AC-3).
952 @item
953 To have a constant quality (but a variable bitrate), use the option
954 '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
955 quality).
957 @end itemize
958 @c man end TIPS
960 @chapter Examples
961 @c man begin EXAMPLES
963 @section Preset files
965 A preset file contains a sequence of @var{option=value} pairs, one for
966 each line, specifying a sequence of options which can be specified also on
967 the command line. Lines starting with the hash ('#') character are ignored and
968 are used to provide comments. Empty lines are also ignored. Check the
969 @file{presets} directory in the Libav source tree for examples.
971 Preset files are specified with the @code{pre} option, this option takes a
972 preset name as input. Avconv searches for a file named @var{preset_name}.avpreset in
973 the directories @file{$AVCONV_DATADIR} (if set), and @file{$HOME/.avconv}, and in
974 the data directory defined at configuration time (usually @file{$PREFIX/share/avconv})
975 in that order. For example, if the argument is @code{libx264-max}, it will
976 search for the file @file{libx264-max.avpreset}.
978 @section Video and Audio grabbing
980 If you specify the input format and device then avconv can grab video
981 and audio directly.
983 @example
984 avconv -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
985 @end example
987 Note that you must activate the right video source and channel before
988 launching avconv with any TV viewer such as
989 @uref{http://linux.bytesex.org/xawtv/, xawtv} by Gerd Knorr. You also
990 have to set the audio recording levels correctly with a
991 standard mixer.
993 @section X11 grabbing
995 Grab the X11 display with avconv via
997 @example
998 avconv -f x11grab -s cif -r 25 -i :0.0 /tmp/out.mpg
999 @end example
1001 0.0 is display.screen number of your X11 server, same as
1002 the DISPLAY environment variable.
1004 @example
1005 avconv -f x11grab -s cif -r 25 -i :0.0+10,20 /tmp/out.mpg
1006 @end example
1008 0.0 is display.screen number of your X11 server, same as the DISPLAY environment
1009 variable. 10 is the x-offset and 20 the y-offset for the grabbing.
1011 @section Video and Audio file format conversion
1013 Any supported file format and protocol can serve as input to avconv:
1015 Examples:
1016 @itemize
1017 @item
1018 You can use YUV files as input:
1020 @example
1021 avconv -i /tmp/test%d.Y /tmp/out.mpg
1022 @end example
1024 It will use the files:
1025 @example
1026 /tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
1027 /tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
1028 @end example
1030 The Y files use twice the resolution of the U and V files. They are
1031 raw files, without header. They can be generated by all decent video
1032 decoders. You must specify the size of the image with the @option{-s} option
1033 if avconv cannot guess it.
1035 @item
1036 You can input from a raw YUV420P file:
1038 @example
1039 avconv -i /tmp/test.yuv /tmp/out.avi
1040 @end example
1042 test.yuv is a file containing raw YUV planar data. Each frame is composed
1043 of the Y plane followed by the U and V planes at half vertical and
1044 horizontal resolution.
1046 @item
1047 You can output to a raw YUV420P file:
1049 @example
1050 avconv -i mydivx.avi hugefile.yuv
1051 @end example
1053 @item
1054 You can set several input files and output files:
1056 @example
1057 avconv -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
1058 @end example
1060 Converts the audio file a.wav and the raw YUV video file a.yuv
1061 to MPEG file a.mpg.
1063 @item
1064 You can also do audio and video conversions at the same time:
1066 @example
1067 avconv -i /tmp/a.wav -ar 22050 /tmp/a.mp2
1068 @end example
1070 Converts a.wav to MPEG audio at 22050 Hz sample rate.
1072 @item
1073 You can encode to several formats at the same time and define a
1074 mapping from input stream to output streams:
1076 @example
1077 avconv -i /tmp/a.wav -map 0:a -b 64k /tmp/a.mp2 -map 0:a -b 128k /tmp/b.mp2
1078 @end example
1080 Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
1081 file:index' specifies which input stream is used for each output
1082 stream, in the order of the definition of output streams.
1084 @item
1085 You can transcode decrypted VOBs:
1087 @example
1088 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
1089 @end example
1091 This is a typical DVD ripping example; the input is a VOB file, the
1092 output an AVI file with MPEG-4 video and MP3 audio. Note that in this
1093 command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
1094 GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
1095 input video. Furthermore, the audio stream is MP3-encoded so you need
1096 to enable LAME support by passing @code{--enable-libmp3lame} to configure.
1097 The mapping is particularly useful for DVD transcoding
1098 to get the desired audio language.
1100 NOTE: To see the supported input formats, use @code{avconv -formats}.
1102 @item
1103 You can extract images from a video, or create a video from many images:
1105 For extracting images from a video:
1106 @example
1107 avconv -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg
1108 @end example
1110 This will extract one video frame per second from the video and will
1111 output them in files named @file{foo-001.jpeg}, @file{foo-002.jpeg},
1112 etc. Images will be rescaled to fit the new WxH values.
1114 If you want to extract just a limited number of frames, you can use the
1115 above command in combination with the -vframes or -t option, or in
1116 combination with -ss to start extracting from a certain point in time.
1118 For creating a video from many images:
1119 @example
1120 avconv -f image2 -i foo-%03d.jpeg -r 12 -s WxH foo.avi
1121 @end example
1123 The syntax @code{foo-%03d.jpeg} specifies to use a decimal number
1124 composed of three digits padded with zeroes to express the sequence
1125 number. It is the same syntax supported by the C printf function, but
1126 only formats accepting a normal integer are suitable.
1128 @item
1129 You can put many streams of the same type in the output:
1131 @example
1132 avconv -i test1.avi -i test2.avi -map 0.3 -map 0.2 -map 0.1 -map 0.0 -c copy test12.nut
1133 @end example
1135 The resulting output file @file{test12.avi} will contain first four streams from
1136 the input file in reverse order.
1138 @item
1139 To force CBR video output:
1140 @example
1141 avconv -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v
1142 @end example
1144 @item
1145 The four options lmin, lmax, mblmin and mblmax use 'lambda' units,
1146 but you may use the QP2LAMBDA constant to easily convert from 'q' units:
1147 @example
1148 avconv -i src.ext -lmax 21*QP2LAMBDA dst.ext
1149 @end example
1151 @end itemize
1152 @c man end EXAMPLES
1154 @include eval.texi
1155 @include decoders.texi
1156 @include encoders.texi
1157 @include demuxers.texi
1158 @include muxers.texi
1159 @include indevs.texi
1160 @include outdevs.texi
1161 @include protocols.texi
1162 @include bitstream_filters.texi
1163 @include filters.texi
1164 @include metadata.texi
1166 @ignore
1168 @setfilename avconv
1169 @settitle avconv video converter
1171 @c man begin SEEALSO
1172 avplay(1), avprobe(1) and the Libav HTML documentation
1173 @c man end
1175 @c man begin AUTHORS
1176 The Libav developers
1177 @c man end
1179 @end ignore
1181 @bye