avconv: add support for VDPAU decoding
[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 | decoded | encoder | encoded data | muxer | output |
92 | file | ---------> | packets | ---------> | frames | ---------> | packets | -------> | file |
93 |_______| |______________| |_________| |______________| |________|
95 @end example
97 @command{avconv} calls the libavformat library (containing demuxers) to read
98 input files and get packets containing encoded data from them. When there are
99 multiple input files, @command{avconv} tries to keep them synchronized by
100 tracking lowest timestamp on any active input stream.
102 Encoded packets are then passed to the decoder (unless streamcopy is selected
103 for the stream, see further for a description). The decoder produces
104 uncompressed frames (raw video/PCM audio/...) which can be processed further by
105 filtering (see next section). After filtering the frames are passed to the
106 encoder, which encodes them and outputs encoded packets again. Finally those are
107 passed to the muxer, which writes the encoded packets to the output file.
109 @section Filtering
110 Before encoding, @command{avconv} can process raw audio and video frames using
111 filters from the libavfilter library. Several chained filters form a filter
112 graph. @command{avconv} distinguishes between two types of filtergraphs -
113 simple and complex.
115 @subsection Simple filtergraphs
116 Simple filtergraphs are those that have exactly one input and output, both of
117 the same type. In the above diagram they can be represented by simply inserting
118 an additional step between decoding and encoding:
120 @example
121 _________ __________ ______________
122 | | | | | |
123 | decoded | simple filtergraph | filtered | encoder | encoded data |
124 | frames | -------------------> | frames | ---------> | packets |
125 |_________| |__________| |______________|
127 @end example
129 Simple filtergraphs are configured with the per-stream @option{-filter} option
130 (with @option{-vf} and @option{-af} aliases for video and audio respectively).
131 A simple filtergraph for video can look for example like this:
133 @example
134 _______ _____________ _______ _____ ________
135 | | | | | | | | | |
136 | input | ---> | deinterlace | ---> | scale | ---> | fps | ---> | output |
137 |_______| |_____________| |_______| |_____| |________|
139 @end example
141 Note that some filters change frame properties but not frame contents. E.g. the
142 @code{fps} filter in the example above changes number of frames, but does not
143 touch the frame contents. Another example is the @code{setpts} filter, which
144 only sets timestamps and otherwise passes the frames unchanged.
146 @subsection Complex filtergraphs
147 Complex filtergraphs are those which cannot be described as simply a linear
148 processing chain applied to one stream. This is the case e.g. when the graph has
149 more than one input and/or output, or when output stream type is different from
150 input. They can be represented with the following diagram:
152 @example
153 _________
154 | |
155 | input 0 |\ __________
156 |_________| \ | |
157 \ _________ /| output 0 |
158 \ | | / |__________|
159 _________ \| complex | /
160 | | | |/
161 | input 1 |---->| filter |\
162 |_________| | | \ __________
163 /| graph | \ | |
164 / | | \| output 1 |
165 _________ / |_________| |__________|
166 | | /
167 | input 2 |/
168 |_________|
170 @end example
172 Complex filtergraphs are configured with the @option{-filter_complex} option.
173 Note that this option is global, since a complex filtergraph by its nature
174 cannot be unambiguously associated with a single stream or file.
176 A trivial example of a complex filtergraph is the @code{overlay} filter, which
177 has two video inputs and one video output, containing one video overlaid on top
178 of the other. Its audio counterpart is the @code{amix} filter.
180 @section Stream copy
181 Stream copy is a mode selected by supplying the @code{copy} parameter to the
182 @option{-codec} option. It makes @command{avconv} omit the decoding and encoding
183 step for the specified stream, so it does only demuxing and muxing. It is useful
184 for changing the container format or modifying container-level metadata. The
185 diagram above will in this case simplify to this:
187 @example
188 _______ ______________ ________
189 | | | | | |
190 | input | demuxer | encoded data | muxer | output |
191 | file | ---------> | packets | -------> | file |
192 |_______| |______________| |________|
194 @end example
196 Since there is no decoding or encoding, it is very fast and there is no quality
197 loss. However it might not work in some cases because of many factors. Applying
198 filters is obviously also impossible, since filters work on uncompressed data.
202 @chapter Stream selection
203 @c man begin STREAM SELECTION
205 By default avconv tries to pick the "best" stream of each type present in input
206 files and add them to each output file. For video, this means the highest
207 resolution, for audio the highest channel count. For subtitle it's simply the
208 first subtitle stream.
210 You can disable some of those defaults by using @code{-vn/-an/-sn} options. For
211 full manual control, use the @code{-map} option, which disables the defaults just
212 described.
214 @c man end STREAM SELECTION
216 @chapter Options
217 @c man begin OPTIONS
219 @include avtools-common-opts.texi
221 @section Main options
223 @table @option
225 @item -f @var{fmt} (@emph{input/output})
226 Force input or output file format. The format is normally autodetected for input
227 files and guessed from file extension for output files, so this option is not
228 needed in most cases.
230 @item -i @var{filename} (@emph{input})
231 input file name
233 @item -y (@emph{global})
234 Overwrite output files without asking.
236 @item -n (@emph{global})
237 Immediately exit when output files already exist.
239 @item -c[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
240 @itemx -codec[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
241 Select an encoder (when used before an output file) or a decoder (when used
242 before an input file) for one or more streams. @var{codec} is the name of a
243 decoder/encoder or a special value @code{copy} (output only) to indicate that
244 the stream is not to be reencoded.
246 For example
247 @example
248 avconv -i INPUT -map 0 -c:v libx264 -c:a copy OUTPUT
249 @end example
250 encodes all video streams with libx264 and copies all audio streams.
252 For each stream, the last matching @code{c} option is applied, so
253 @example
254 avconv -i INPUT -map 0 -c copy -c:v:1 libx264 -c:a:137 libvorbis OUTPUT
255 @end example
256 will copy all the streams except the second video, which will be encoded with
257 libx264, and the 138th audio, which will be encoded with libvorbis.
259 @item -t @var{duration} (@emph{output})
260 Stop writing the output after its duration reaches @var{duration}.
261 @var{duration} may be a number in seconds, or in @code{hh:mm:ss[.xxx]} form.
263 @item -fs @var{limit_size} (@emph{output})
264 Set the file size limit.
266 @item -ss @var{position} (@emph{input/output})
267 When used as an input option (before @code{-i}), seeks in this input file to
268 @var{position}. Note the in most formats it is not possible to seek exactly, so
269 @command{avconv} will seek to the closest seek point before @var{position}.
270 When transcoding and @option{-accurate_seek} is enabled (the default), this
271 extra segment between the seek point and @var{position} will be decoded and
272 discarded. When doing stream copy or when @option{-noaccurate_seek} is used, it
273 will be preserved.
275 When used as an output option (before an output filename), decodes but discards
276 input until the timestamps reach @var{position}.
278 @var{position} may be either in seconds or in @code{hh:mm:ss[.xxx]} form.
280 @item -itsoffset @var{offset} (@emph{input})
281 Set the input time offset in seconds.
282 @code{[-]hh:mm:ss[.xxx]} syntax is also supported.
283 The offset is added to the timestamps of the input files.
284 Specifying a positive offset means that the corresponding
285 streams are delayed by @var{offset} seconds.
287 @item -metadata[:metadata_specifier] @var{key}=@var{value} (@emph{output,per-metadata})
288 Set a metadata key/value pair.
290 An optional @var{metadata_specifier} may be given to set metadata
291 on streams or chapters. See @code{-map_metadata} documentation for
292 details.
294 This option overrides metadata set with @code{-map_metadata}. It is
295 also possible to delete metadata by using an empty value.
297 For example, for setting the title in the output file:
298 @example
299 avconv -i in.avi -metadata title="my title" out.flv
300 @end example
302 To set the language of the first audio stream:
303 @example
304 avconv -i INPUT -metadata:s:a:0 language=eng OUTPUT
305 @end example
307 @item -target @var{type} (@emph{output})
308 Specify target file type (@code{vcd}, @code{svcd}, @code{dvd}, @code{dv},
309 @code{dv50}). @var{type} may be prefixed with @code{pal-}, @code{ntsc-} or
310 @code{film-} to use the corresponding standard. All the format options
311 (bitrate, codecs, buffer sizes) are then set automatically. You can just type:
313 @example
314 avconv -i myfile.avi -target vcd /tmp/vcd.mpg
315 @end example
317 Nevertheless you can specify additional options as long as you know
318 they do not conflict with the standard, as in:
320 @example
321 avconv -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
322 @end example
324 @item -dframes @var{number} (@emph{output})
325 Set the number of data frames to record. This is an alias for @code{-frames:d}.
327 @item -frames[:@var{stream_specifier}] @var{framecount} (@emph{output,per-stream})
328 Stop writing to the stream after @var{framecount} frames.
330 @item -q[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
331 @itemx -qscale[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
332 Use fixed quality scale (VBR). The meaning of @var{q} is
333 codec-dependent.
335 @item -filter[:@var{stream_specifier}] @var{filter_graph} (@emph{output,per-stream})
336 @var{filter_graph} is a description of the filter graph to apply to
337 the stream. Use @code{-filters} to show all the available filters
338 (including also sources and sinks).
340 See also the @option{-filter_complex} option if you want to create filter graphs
341 with multiple inputs and/or outputs.
343 @item -filter_script[:@var{stream_specifier}] @var{filename} (@emph{output,per-stream})
344 This option is similar to @option{-filter}, the only difference is that its
345 argument is the name of the file from which a filtergraph description is to be
346 read.
348 @item -pre[:@var{stream_specifier}] @var{preset_name} (@emph{output,per-stream})
349 Specify the preset for matching stream(s).
351 @item -stats (@emph{global})
352 Print encoding progress/statistics. On by default.
354 @item -attach @var{filename} (@emph{output})
355 Add an attachment to the output file. This is supported by a few formats
356 like Matroska for e.g. fonts used in rendering subtitles. Attachments
357 are implemented as a specific type of stream, so this option will add
358 a new stream to the file. It is then possible to use per-stream options
359 on this stream in the usual way. Attachment streams created with this
360 option will be created after all the other streams (i.e. those created
361 with @code{-map} or automatic mappings).
363 Note that for Matroska you also have to set the mimetype metadata tag:
364 @example
365 avconv -i INPUT -attach DejaVuSans.ttf -metadata:s:2 mimetype=application/x-truetype-font out.mkv
366 @end example
367 (assuming that the attachment stream will be third in the output file).
369 @item -dump_attachment[:@var{stream_specifier}] @var{filename} (@emph{input,per-stream})
370 Extract the matching attachment stream into a file named @var{filename}. If
371 @var{filename} is empty, then the value of the @code{filename} metadata tag
372 will be used.
374 E.g. to extract the first attachment to a file named 'out.ttf':
375 @example
376 avconv -dump_attachment:t:0 out.ttf INPUT
377 @end example
378 To extract all attachments to files determined by the @code{filename} tag:
379 @example
380 avconv -dump_attachment:t "" INPUT
381 @end example
383 Technical note -- attachments are implemented as codec extradata, so this
384 option can actually be used to extract extradata from any stream, not just
385 attachments.
387 @end table
389 @section Video Options
391 @table @option
392 @item -vframes @var{number} (@emph{output})
393 Set the number of video frames to record. This is an alias for @code{-frames:v}.
394 @item -r[:@var{stream_specifier}] @var{fps} (@emph{input/output,per-stream})
395 Set frame rate (Hz value, fraction or abbreviation).
397 As an input option, ignore any timestamps stored in the file and instead
398 generate timestamps assuming constant frame rate @var{fps}.
400 As an output option, duplicate or drop input frames to achieve constant output
401 frame rate @var{fps} (note that this actually causes the @code{fps} filter to be
402 inserted to the end of the corresponding filtergraph).
404 @item -s[:@var{stream_specifier}] @var{size} (@emph{input/output,per-stream})
405 Set frame size.
407 As an input option, this is a shortcut for the @option{video_size} private
408 option, recognized by some demuxers for which the frame size is either not
409 stored in the file or is configurable -- e.g. raw video or video grabbers.
411 As an output option, this inserts the @code{scale} video filter to the
412 @emph{end} of the corresponding filtergraph. Please use the @code{scale} filter
413 directly to insert it at the beginning or some other place.
415 The format is @samp{wxh} (default - same as source). The following
416 abbreviations are recognized:
417 @table @samp
418 @item sqcif
419 128x96
420 @item qcif
421 176x144
422 @item cif
423 352x288
424 @item 4cif
425 704x576
426 @item 16cif
427 1408x1152
428 @item qqvga
429 160x120
430 @item qvga
431 320x240
432 @item vga
433 640x480
434 @item svga
435 800x600
436 @item xga
437 1024x768
438 @item uxga
439 1600x1200
440 @item qxga
441 2048x1536
442 @item sxga
443 1280x1024
444 @item qsxga
445 2560x2048
446 @item hsxga
447 5120x4096
448 @item wvga
449 852x480
450 @item wxga
451 1366x768
452 @item wsxga
453 1600x1024
454 @item wuxga
455 1920x1200
456 @item woxga
457 2560x1600
458 @item wqsxga
459 3200x2048
460 @item wquxga
461 3840x2400
462 @item whsxga
463 6400x4096
464 @item whuxga
465 7680x4800
466 @item cga
467 320x200
468 @item ega
469 640x350
470 @item hd480
471 852x480
472 @item hd720
473 1280x720
474 @item hd1080
475 1920x1080
476 @end table
478 @item -aspect[:@var{stream_specifier}] @var{aspect} (@emph{output,per-stream})
479 Set the video display aspect ratio specified by @var{aspect}.
481 @var{aspect} can be a floating point number string, or a string of the
482 form @var{num}:@var{den}, where @var{num} and @var{den} are the
483 numerator and denominator of the aspect ratio. For example "4:3",
484 "16:9", "1.3333", and "1.7777" are valid argument values.
486 @item -vn (@emph{output})
487 Disable video recording.
489 @item -vcodec @var{codec} (@emph{output})
490 Set the video codec. This is an alias for @code{-codec:v}.
492 @item -pass[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
493 Select the pass number (1 or 2). It is used to do two-pass
494 video encoding. The statistics of the video are recorded in the first
495 pass into a log file (see also the option -passlogfile),
496 and in the second pass that log file is used to generate the video
497 at the exact requested bitrate.
498 On pass 1, you may just deactivate audio and set output to null,
499 examples for Windows and Unix:
500 @example
501 avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y NUL
502 avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null
503 @end example
505 @item -passlogfile[:@var{stream_specifier}] @var{prefix} (@emph{output,per-stream})
506 Set two-pass log file name prefix to @var{prefix}, the default file name
507 prefix is ``av2pass''. The complete file name will be
508 @file{PREFIX-N.log}, where N is a number specific to the output
509 stream.
511 @item -vf @var{filter_graph} (@emph{output})
512 @var{filter_graph} is a description of the filter graph to apply to
513 the input video.
514 Use the option "-filters" to show all the available filters (including
515 also sources and sinks). This is an alias for @code{-filter:v}.
517 @end table
519 @section Advanced Video Options
521 @table @option
522 @item -pix_fmt[:@var{stream_specifier}] @var{format} (@emph{input/output,per-stream})
523 Set pixel format. Use @code{-pix_fmts} to show all the supported
524 pixel formats.
525 @item -sws_flags @var{flags} (@emph{input/output})
526 Set SwScaler flags.
527 @item -vdt @var{n}
528 Discard threshold.
530 @item -rc_override[:@var{stream_specifier}] @var{override} (@emph{output,per-stream})
531 rate control override for specific intervals
533 @item -vstats
534 Dump video coding statistics to @file{vstats_HHMMSS.log}.
535 @item -vstats_file @var{file}
536 Dump video coding statistics to @var{file}.
537 @item -top[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
538 top=1/bottom=0/auto=-1 field first
539 @item -dc @var{precision}
540 Intra_dc_precision.
541 @item -vtag @var{fourcc/tag} (@emph{output})
542 Force video tag/fourcc. This is an alias for @code{-tag:v}.
543 @item -qphist (@emph{global})
544 Show QP histogram.
545 @item -force_key_frames[:@var{stream_specifier}] @var{time}[,@var{time}...] (@emph{output,per-stream})
546 Force key frames at the specified timestamps, more precisely at the first
547 frames after each specified time.
548 This option can be useful to ensure that a seek point is present at a
549 chapter mark or any other designated place in the output file.
550 The timestamps must be specified in ascending order.
552 @item -copyinkf[:@var{stream_specifier}] (@emph{output,per-stream})
553 When doing stream copy, copy also non-key frames found at the
554 beginning.
556 @item -hwaccel[:@var{stream_specifier}] @var{hwaccel} (@emph{input,per-stream})
557 Use hardware acceleration to decode the matching stream(s). The allowed values
558 of @var{hwaccel} are:
559 @table @option
560 @item none
561 Do not use any hardware acceleration (the default).
563 @item auto
564 Automatically select the hardware acceleration method.
566 @item vdpau
567 Use VDPAU (Video Decode and Presentation API for Unix) hardware acceleration.
568 @end table
570 This option has no effect if the selected hwaccel is not available or not
571 supported by the chosen decoder.
573 Note that most acceleration methods are intended for playback and will not be
574 faster than software decoding on modern CPUs. Additionally, @command{avconv}
575 will usually need to copy the decoded frames from the GPU memory into the system
576 memory, resulting in further performance loss. This option is thus mainly
577 useful for testing.
579 @item -hwaccel_device[:@var{stream_specifier}] @var{hwaccel_device} (@emph{input,per-stream})
580 Select a device to use for hardware acceleration.
582 This option only makes sense when the @option{-hwaccel} option is also
583 specified. Its exact meaning depends on the specific hardware acceleration
584 method chosen.
586 @table @option
587 @item vdpau
588 For VDPAU, this option specifies the X11 display/screen to use. If this option
589 is not specified, the value of the @var{DISPLAY} environment variable is used
590 @end table
591 @end table
593 @section Audio Options
595 @table @option
596 @item -aframes @var{number} (@emph{output})
597 Set the number of audio frames to record. This is an alias for @code{-frames:a}.
598 @item -ar[:@var{stream_specifier}] @var{freq} (@emph{input/output,per-stream})
599 Set the audio sampling frequency. For output streams it is set by
600 default to the frequency of the corresponding input stream. For input
601 streams this option only makes sense for audio grabbing devices and raw
602 demuxers and is mapped to the corresponding demuxer options.
603 @item -aq @var{q} (@emph{output})
604 Set the audio quality (codec-specific, VBR). This is an alias for -q:a.
605 @item -ac[:@var{stream_specifier}] @var{channels} (@emph{input/output,per-stream})
606 Set the number of audio channels. For output streams it is set by
607 default to the number of input audio channels. For input streams
608 this option only makes sense for audio grabbing devices and raw demuxers
609 and is mapped to the corresponding demuxer options.
610 @item -an (@emph{output})
611 Disable audio recording.
612 @item -acodec @var{codec} (@emph{input/output})
613 Set the audio codec. This is an alias for @code{-codec:a}.
614 @item -sample_fmt[:@var{stream_specifier}] @var{sample_fmt} (@emph{output,per-stream})
615 Set the audio sample format. Use @code{-sample_fmts} to get a list
616 of supported sample formats.
617 @item -af @var{filter_graph} (@emph{output})
618 @var{filter_graph} is a description of the filter graph to apply to
619 the input audio.
620 Use the option "-filters" to show all the available filters (including
621 also sources and sinks). This is an alias for @code{-filter:a}.
622 @end table
624 @section Advanced Audio options:
626 @table @option
627 @item -atag @var{fourcc/tag} (@emph{output})
628 Force audio tag/fourcc. This is an alias for @code{-tag:a}.
629 @end table
631 @section Subtitle options:
633 @table @option
634 @item -scodec @var{codec} (@emph{input/output})
635 Set the subtitle codec. This is an alias for @code{-codec:s}.
636 @item -sn (@emph{output})
637 Disable subtitle recording.
638 @end table
640 @section Advanced options
642 @table @option
643 @item -map [-]@var{input_file_id}[:@var{stream_specifier}][,@var{sync_file_id}[:@var{stream_specifier}]] | @var{[linklabel]} (@emph{output})
645 Designate one or more input streams as a source for the output file. Each input
646 stream is identified by the input file index @var{input_file_id} and
647 the input stream index @var{input_stream_id} within the input
648 file. Both indices start at 0. If specified,
649 @var{sync_file_id}:@var{stream_specifier} sets which input stream
650 is used as a presentation sync reference.
652 The first @code{-map} option on the command line specifies the
653 source for output stream 0, the second @code{-map} option specifies
654 the source for output stream 1, etc.
656 A @code{-} character before the stream identifier creates a "negative" mapping.
657 It disables matching streams from already created mappings.
659 An alternative @var{[linklabel]} form will map outputs from complex filter
660 graphs (see the @option{-filter_complex} option) to the output file.
661 @var{linklabel} must correspond to a defined output link label in the graph.
663 For example, to map ALL streams from the first input file to output
664 @example
665 avconv -i INPUT -map 0 output
666 @end example
668 For example, if you have two audio streams in the first input file,
669 these streams are identified by "0:0" and "0:1". You can use
670 @code{-map} to select which streams to place in an output file. For
671 example:
672 @example
673 avconv -i INPUT -map 0:1 out.wav
674 @end example
675 will map the input stream in @file{INPUT} identified by "0:1" to
676 the (single) output stream in @file{out.wav}.
678 For example, to select the stream with index 2 from input file
679 @file{a.mov} (specified by the identifier "0:2"), and stream with
680 index 6 from input @file{b.mov} (specified by the identifier "1:6"),
681 and copy them to the output file @file{out.mov}:
682 @example
683 avconv -i a.mov -i b.mov -c copy -map 0:2 -map 1:6 out.mov
684 @end example
686 To select all video and the third audio stream from an input file:
687 @example
688 avconv -i INPUT -map 0:v -map 0:a:2 OUTPUT
689 @end example
691 To map all the streams except the second audio, use negative mappings
692 @example
693 avconv -i INPUT -map 0 -map -0:a:1 OUTPUT
694 @end example
696 Note that using this option disables the default mappings for this output file.
698 @item -map_metadata[:@var{metadata_spec_out}] @var{infile}[:@var{metadata_spec_in}] (@emph{output,per-metadata})
699 Set metadata information of the next output file from @var{infile}. Note that
700 those are file indices (zero-based), not filenames.
701 Optional @var{metadata_spec_in/out} parameters specify, which metadata to copy.
702 A metadata specifier can have the following forms:
703 @table @option
704 @item @var{g}
705 global metadata, i.e. metadata that applies to the whole file
707 @item @var{s}[:@var{stream_spec}]
708 per-stream metadata. @var{stream_spec} is a stream specifier as described
709 in the @ref{Stream specifiers} chapter. In an input metadata specifier, the first
710 matching stream is copied from. In an output metadata specifier, all matching
711 streams are copied to.
713 @item @var{c}:@var{chapter_index}
714 per-chapter metadata. @var{chapter_index} is the zero-based chapter index.
716 @item @var{p}:@var{program_index}
717 per-program metadata. @var{program_index} is the zero-based program index.
718 @end table
719 If metadata specifier is omitted, it defaults to global.
721 By default, global metadata is copied from the first input file,
722 per-stream and per-chapter metadata is copied along with streams/chapters. These
723 default mappings are disabled by creating any mapping of the relevant type. A negative
724 file index can be used to create a dummy mapping that just disables automatic copying.
726 For example to copy metadata from the first stream of the input file to global metadata
727 of the output file:
728 @example
729 avconv -i in.ogg -map_metadata 0:s:0 out.mp3
730 @end example
732 To do the reverse, i.e. copy global metadata to all audio streams:
733 @example
734 avconv -i in.mkv -map_metadata:s:a 0:g out.mkv
735 @end example
736 Note that simple @code{0} would work as well in this example, since global
737 metadata is assumed by default.
739 @item -map_chapters @var{input_file_index} (@emph{output})
740 Copy chapters from input file with index @var{input_file_index} to the next
741 output file. If no chapter mapping is specified, then chapters are copied from
742 the first input file with at least one chapter. Use a negative file index to
743 disable any chapter copying.
744 @item -debug
745 Print specific debug info.
746 @item -benchmark (@emph{global})
747 Show benchmarking information at the end of an encode.
748 Shows CPU time used and maximum memory consumption.
749 Maximum memory consumption is not supported on all systems,
750 it will usually display as 0 if not supported.
751 @item -timelimit @var{duration} (@emph{global})
752 Exit after avconv has been running for @var{duration} seconds.
753 @item -dump (@emph{global})
754 Dump each input packet to stderr.
755 @item -hex (@emph{global})
756 When dumping packets, also dump the payload.
757 @item -re (@emph{input})
758 Read input at native frame rate. Mainly used to simulate a grab device
759 or live input stream (e.g. when reading from a file). Should not be used
760 with actual grab devices or live input streams (where it can cause packet
761 loss).
762 @item -vsync @var{parameter}
763 Video sync method.
765 @table @option
766 @item passthrough
767 Each frame is passed with its timestamp from the demuxer to the muxer.
768 @item cfr
769 Frames will be duplicated and dropped to achieve exactly the requested
770 constant framerate.
771 @item vfr
772 Frames are passed through with their timestamp or dropped so as to
773 prevent 2 frames from having the same timestamp.
774 @item auto
775 Chooses between 1 and 2 depending on muxer capabilities. This is the
776 default method.
777 @end table
779 With -map you can select from which stream the timestamps should be
780 taken. You can leave either video or audio unchanged and sync the
781 remaining stream(s) to the unchanged one.
783 @item -async @var{samples_per_second}
784 Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
785 the parameter is the maximum samples per second by which the audio is changed.
786 -async 1 is a special case where only the start of the audio stream is corrected
787 without any later correction.
788 This option has been deprecated. Use the @code{asyncts} audio filter instead.
789 @item -copyts
790 Copy timestamps from input to output.
791 @item -copytb
792 Copy input stream time base from input to output when stream copying.
793 @item -shortest (@emph{output})
794 Finish encoding when the shortest input stream ends.
795 @item -dts_delta_threshold
796 Timestamp discontinuity delta threshold.
797 @item -muxdelay @var{seconds} (@emph{input})
798 Set the maximum demux-decode delay.
799 @item -muxpreload @var{seconds} (@emph{input})
800 Set the initial demux-decode delay.
801 @item -streamid @var{output-stream-index}:@var{new-value} (@emph{output})
802 Assign a new stream-id value to an output stream. This option should be
803 specified prior to the output filename to which it applies.
804 For the situation where multiple output files exist, a streamid
805 may be reassigned to a different value.
807 For example, to set the stream 0 PID to 33 and the stream 1 PID to 36 for
808 an output mpegts file:
809 @example
810 avconv -i infile -streamid 0:33 -streamid 1:36 out.ts
811 @end example
813 @item -bsf[:@var{stream_specifier}] @var{bitstream_filters} (@emph{output,per-stream})
814 Set bitstream filters for matching streams. @var{bistream_filters} is
815 a comma-separated list of bitstream filters. Use the @code{-bsfs} option
816 to get the list of bitstream filters.
817 @example
818 avconv -i h264.mp4 -c:v copy -bsf:v h264_mp4toannexb -an out.h264
819 @end example
820 @example
821 avconv -i file.mov -an -vn -bsf:s mov2textsub -c:s copy -f rawvideo sub.txt
822 @end example
824 @item -tag[:@var{stream_specifier}] @var{codec_tag} (@emph{output,per-stream})
825 Force a tag/fourcc for matching streams.
827 @item -filter_complex @var{filtergraph} (@emph{global})
828 Define a complex filter graph, i.e. one with arbitrary number of inputs and/or
829 outputs. For simple graphs -- those with one input and one output of the same
830 type -- see the @option{-filter} options. @var{filtergraph} is a description of
831 the filter graph, as described in @ref{Filtergraph syntax}.
833 Input link labels must refer to input streams using the
834 @code{[file_index:stream_specifier]} syntax (i.e. the same as @option{-map}
835 uses). If @var{stream_specifier} matches multiple streams, the first one will be
836 used. An unlabeled input will be connected to the first unused input stream of
837 the matching type.
839 Output link labels are referred to with @option{-map}. Unlabeled outputs are
840 added to the first output file.
842 Note that with this option it is possible to use only lavfi sources without
843 normal input files.
845 For example, to overlay an image over video
846 @example
847 avconv -i video.mkv -i image.png -filter_complex '[0:v][1:v]overlay[out]' -map
848 '[out]' out.mkv
849 @end example
850 Here @code{[0:v]} refers to the first video stream in the first input file,
851 which is linked to the first (main) input of the overlay filter. Similarly the
852 first video stream in the second input is linked to the second (overlay) input
853 of overlay.
855 Assuming there is only one video stream in each input file, we can omit input
856 labels, so the above is equivalent to
857 @example
858 avconv -i video.mkv -i image.png -filter_complex 'overlay[out]' -map
859 '[out]' out.mkv
860 @end example
862 Furthermore we can omit the output label and the single output from the filter
863 graph will be added to the output file automatically, so we can simply write
864 @example
865 avconv -i video.mkv -i image.png -filter_complex 'overlay' out.mkv
866 @end example
868 To generate 5 seconds of pure red video using lavfi @code{color} source:
869 @example
870 avconv -filter_complex 'color=red' -t 5 out.mkv
871 @end example
873 @item -filter_complex_script @var{filename} (@emph{global})
874 This option is similar to @option{-filter_complex}, the only difference is that
875 its argument is the name of the file from which a complex filtergraph
876 description is to be read.
878 @item -accurate_seek (@emph{input})
879 This option enables or disables accurate seeking in input files with the
880 @option{-ss} option. It is enabled by default, so seeking is accurate when
881 transcoding. Use @option{-noaccurate_seek} to disable it, which may be useful
882 e.g. when copying some streams and transcoding the others.
884 @end table
885 @c man end OPTIONS
887 @chapter Tips
888 @c man begin TIPS
890 @itemize
891 @item
892 For streaming at very low bitrate application, use a low frame rate
893 and a small GOP size. This is especially true for RealVideo where
894 the Linux player does not seem to be very fast, so it can miss
895 frames. An example is:
897 @example
898 avconv -g 3 -r 3 -t 10 -b 50k -s qcif -f rv10 /tmp/b.rm
899 @end example
901 @item
902 The parameter 'q' which is displayed while encoding is the current
903 quantizer. The value 1 indicates that a very good quality could
904 be achieved. The value 31 indicates the worst quality. If q=31 appears
905 too often, it means that the encoder cannot compress enough to meet
906 your bitrate. You must either increase the bitrate, decrease the
907 frame rate or decrease the frame size.
909 @item
910 If your computer is not fast enough, you can speed up the
911 compression at the expense of the compression ratio. You can use
912 '-me zero' to speed up motion estimation, and '-g 0' to disable
913 motion estimation completely (you have only I-frames, which means it
914 is about as good as JPEG compression).
916 @item
917 To have very low audio bitrates, reduce the sampling frequency
918 (down to 22050 Hz for MPEG audio, 22050 or 11025 for AC-3).
920 @item
921 To have a constant quality (but a variable bitrate), use the option
922 '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
923 quality).
925 @end itemize
926 @c man end TIPS
928 @chapter Examples
929 @c man begin EXAMPLES
931 @section Preset files
933 A preset file contains a sequence of @var{option=value} pairs, one for
934 each line, specifying a sequence of options which can be specified also on
935 the command line. Lines starting with the hash ('#') character are ignored and
936 are used to provide comments. Empty lines are also ignored. Check the
937 @file{presets} directory in the Libav source tree for examples.
939 Preset files are specified with the @code{pre} option, this option takes a
940 preset name as input. Avconv searches for a file named @var{preset_name}.avpreset in
941 the directories @file{$AVCONV_DATADIR} (if set), and @file{$HOME/.avconv}, and in
942 the data directory defined at configuration time (usually @file{$PREFIX/share/avconv})
943 in that order. For example, if the argument is @code{libx264-max}, it will
944 search for the file @file{libx264-max.avpreset}.
946 @section Video and Audio grabbing
948 If you specify the input format and device then avconv can grab video
949 and audio directly.
951 @example
952 avconv -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
953 @end example
955 Note that you must activate the right video source and channel before
956 launching avconv with any TV viewer such as
957 @uref{http://linux.bytesex.org/xawtv/, xawtv} by Gerd Knorr. You also
958 have to set the audio recording levels correctly with a
959 standard mixer.
961 @section X11 grabbing
963 Grab the X11 display with avconv via
965 @example
966 avconv -f x11grab -s cif -r 25 -i :0.0 /tmp/out.mpg
967 @end example
969 0.0 is display.screen number of your X11 server, same as
970 the DISPLAY environment variable.
972 @example
973 avconv -f x11grab -s cif -r 25 -i :0.0+10,20 /tmp/out.mpg
974 @end example
976 0.0 is display.screen number of your X11 server, same as the DISPLAY environment
977 variable. 10 is the x-offset and 20 the y-offset for the grabbing.
979 @section Video and Audio file format conversion
981 Any supported file format and protocol can serve as input to avconv:
983 Examples:
984 @itemize
985 @item
986 You can use YUV files as input:
988 @example
989 avconv -i /tmp/test%d.Y /tmp/out.mpg
990 @end example
992 It will use the files:
993 @example
994 /tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
995 /tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
996 @end example
998 The Y files use twice the resolution of the U and V files. They are
999 raw files, without header. They can be generated by all decent video
1000 decoders. You must specify the size of the image with the @option{-s} option
1001 if avconv cannot guess it.
1003 @item
1004 You can input from a raw YUV420P file:
1006 @example
1007 avconv -i /tmp/test.yuv /tmp/out.avi
1008 @end example
1010 test.yuv is a file containing raw YUV planar data. Each frame is composed
1011 of the Y plane followed by the U and V planes at half vertical and
1012 horizontal resolution.
1014 @item
1015 You can output to a raw YUV420P file:
1017 @example
1018 avconv -i mydivx.avi hugefile.yuv
1019 @end example
1021 @item
1022 You can set several input files and output files:
1024 @example
1025 avconv -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
1026 @end example
1028 Converts the audio file a.wav and the raw YUV video file a.yuv
1029 to MPEG file a.mpg.
1031 @item
1032 You can also do audio and video conversions at the same time:
1034 @example
1035 avconv -i /tmp/a.wav -ar 22050 /tmp/a.mp2
1036 @end example
1038 Converts a.wav to MPEG audio at 22050 Hz sample rate.
1040 @item
1041 You can encode to several formats at the same time and define a
1042 mapping from input stream to output streams:
1044 @example
1045 avconv -i /tmp/a.wav -map 0:a -b 64k /tmp/a.mp2 -map 0:a -b 128k /tmp/b.mp2
1046 @end example
1048 Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
1049 file:index' specifies which input stream is used for each output
1050 stream, in the order of the definition of output streams.
1052 @item
1053 You can transcode decrypted VOBs:
1055 @example
1056 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
1057 @end example
1059 This is a typical DVD ripping example; the input is a VOB file, the
1060 output an AVI file with MPEG-4 video and MP3 audio. Note that in this
1061 command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
1062 GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
1063 input video. Furthermore, the audio stream is MP3-encoded so you need
1064 to enable LAME support by passing @code{--enable-libmp3lame} to configure.
1065 The mapping is particularly useful for DVD transcoding
1066 to get the desired audio language.
1068 NOTE: To see the supported input formats, use @code{avconv -formats}.
1070 @item
1071 You can extract images from a video, or create a video from many images:
1073 For extracting images from a video:
1074 @example
1075 avconv -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg
1076 @end example
1078 This will extract one video frame per second from the video and will
1079 output them in files named @file{foo-001.jpeg}, @file{foo-002.jpeg},
1080 etc. Images will be rescaled to fit the new WxH values.
1082 If you want to extract just a limited number of frames, you can use the
1083 above command in combination with the -vframes or -t option, or in
1084 combination with -ss to start extracting from a certain point in time.
1086 For creating a video from many images:
1087 @example
1088 avconv -f image2 -i foo-%03d.jpeg -r 12 -s WxH foo.avi
1089 @end example
1091 The syntax @code{foo-%03d.jpeg} specifies to use a decimal number
1092 composed of three digits padded with zeroes to express the sequence
1093 number. It is the same syntax supported by the C printf function, but
1094 only formats accepting a normal integer are suitable.
1096 @item
1097 You can put many streams of the same type in the output:
1099 @example
1100 avconv -i test1.avi -i test2.avi -map 0.3 -map 0.2 -map 0.1 -map 0.0 -c copy test12.nut
1101 @end example
1103 The resulting output file @file{test12.avi} will contain first four streams from
1104 the input file in reverse order.
1106 @item
1107 To force CBR video output:
1108 @example
1109 avconv -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v
1110 @end example
1112 @item
1113 The four options lmin, lmax, mblmin and mblmax use 'lambda' units,
1114 but you may use the QP2LAMBDA constant to easily convert from 'q' units:
1115 @example
1116 avconv -i src.ext -lmax 21*QP2LAMBDA dst.ext
1117 @end example
1119 @end itemize
1120 @c man end EXAMPLES
1122 @include eval.texi
1123 @include encoders.texi
1124 @include demuxers.texi
1125 @include muxers.texi
1126 @include indevs.texi
1127 @include outdevs.texi
1128 @include protocols.texi
1129 @include bitstream_filters.texi
1130 @include filters.texi
1131 @include metadata.texi
1133 @ignore
1135 @setfilename avconv
1136 @settitle avconv video converter
1138 @c man begin SEEALSO
1139 avplay(1), avprobe(1) and the Libav HTML documentation
1140 @c man end
1142 @c man begin AUTHORS
1143 The Libav developers
1144 @c man end
1146 @end ignore
1148 @bye