1 \input texinfo @c -*- texinfo -*-
3 @settitle avconv Documentation
5 @center @titlefont{avconv Documentation}
14 The generic syntax is:
18 avconv [global options] [[infile options][@option{-i} @var{infile}]]... @{[outfile options] @var{outfile}@}...
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.
59 To set the video bitrate of the output file to 64kbit/s:
61 avconv -i input.avi -b 64k output.avi
65 To force the frame rate of the output file to 24 fps:
67 avconv -i input.avi -r 24 output.avi
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:
74 avconv -r 1 -i input.m2v -r 24 output.avi
78 The format option may be needed for raw input files.
80 @c man end DESCRIPTION
82 @chapter Detailed description
83 @c man begin DETAILED DESCRIPTION
85 The transcoding process in @command{avconv} for each output can be described by
86 the following diagram:
89 _______ ______________ _________ ______________ ________
91 | input | demuxer | encoded data | decoder | decoded | encoder | encoded data | muxer | output |
92 | file | ---------> | packets | ---------> | frames | ---------> | packets | -------> | file |
93 |_______| |______________| |_________| |______________| |________|
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.
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 -
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:
121 _________ __________ ______________
123 | decoded | simple filtergraph | filtered | encoder | encoded data |
124 | frames | -------------------> | frames | ---------> | packets |
125 |_________| |__________| |______________|
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:
134 _______ _____________ _______ _____ ________
136 | input | ---> | deinterlace | ---> | scale | ---> | fps | ---> | output |
137 |_______| |_____________| |_______| |_____| |________|
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:
155 | input 0 |\ __________
157 \ _________ /| output 0 |
159 _________ \| complex | /
161 | input 1 |---->| filter |\
162 |_________| | | \ __________
165 _________ / |_________| |__________|
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.
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:
188 _______ ______________ ________
190 | input | demuxer | encoded data | muxer | output |
191 | file | ---------> | packets | -------> | file |
192 |_______| |______________| |________|
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.
200 @c man end DETAILED DESCRIPTION
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
214 @c man end STREAM SELECTION
219 @include avtools-common-opts.texi
221 @section Main options
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})
233 @item -y (@emph{global})
234 Overwrite output files without asking.
236 @item -c[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
237 @itemx -codec[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
238 Select an encoder (when used before an output file) or a decoder (when used
239 before an input file) for one or more streams. @var{codec} is the name of a
240 decoder/encoder or a special value @code{copy} (output only) to indicate that
241 the stream is not to be reencoded.
245 avconv -i INPUT -map 0 -c:v libx264 -c:a copy OUTPUT
247 encodes all video streams with libx264 and copies all audio streams.
249 For each stream, the last matching @code{c} option is applied, so
251 avconv -i INPUT -map 0 -c copy -c:v:1 libx264 -c:a:137 libvorbis OUTPUT
253 will copy all the streams except the second video, which will be encoded with
254 libx264, and the 138th audio, which will be encoded with libvorbis.
256 @item -t @var{duration} (@emph{output})
257 Stop writing the output after its duration reaches @var{duration}.
258 @var{duration} may be a number in seconds, or in @code{hh:mm:ss[.xxx]} form.
260 @item -fs @var{limit_size} (@emph{output})
261 Set the file size limit.
263 @item -ss @var{position} (@emph{input/output})
264 When used as an input option (before @code{-i}), seeks in this input file to
265 @var{position}. When used as an output option (before an output filename),
266 decodes but discards input until the timestamps reach @var{position}. This is
267 slower, but more accurate.
269 @var{position} may be either in seconds or in @code{hh:mm:ss[.xxx]} form.
271 @item -itsoffset @var{offset} (@emph{input})
272 Set the input time offset in seconds.
273 @code{[-]hh:mm:ss[.xxx]} syntax is also supported.
274 The offset is added to the timestamps of the input files.
275 Specifying a positive offset means that the corresponding
276 streams are delayed by @var{offset} seconds.
278 @item -metadata[:metadata_specifier] @var{key}=@var{value} (@emph{output,per-metadata})
279 Set a metadata key/value pair.
281 An optional @var{metadata_specifier} may be given to set metadata
282 on streams or chapters. See @code{-map_metadata} documentation for
285 This option overrides metadata set with @code{-map_metadata}. It is
286 also possible to delete metadata by using an empty value.
288 For example, for setting the title in the output file:
290 avconv -i in.avi -metadata title="my title" out.flv
293 To set the language of the first audio stream:
295 avconv -i INPUT -metadata:s:a:0 language=eng OUTPUT
298 @item -target @var{type} (@emph{output})
299 Specify target file type (@code{vcd}, @code{svcd}, @code{dvd}, @code{dv},
300 @code{dv50}). @var{type} may be prefixed with @code{pal-}, @code{ntsc-} or
301 @code{film-} to use the corresponding standard. All the format options
302 (bitrate, codecs, buffer sizes) are then set automatically. You can just type:
305 avconv -i myfile.avi -target vcd /tmp/vcd.mpg
308 Nevertheless you can specify additional options as long as you know
309 they do not conflict with the standard, as in:
312 avconv -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
315 @item -dframes @var{number} (@emph{output})
316 Set the number of data frames to record. This is an alias for @code{-frames:d}.
318 @item -frames[:@var{stream_specifier}] @var{framecount} (@emph{output,per-stream})
319 Stop writing to the stream after @var{framecount} frames.
321 @item -q[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
322 @itemx -qscale[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
323 Use fixed quality scale (VBR). The meaning of @var{q} is
326 @item -filter[:@var{stream_specifier}] @var{filter_graph} (@emph{output,per-stream})
327 @var{filter_graph} is a description of the filter graph to apply to
328 the stream. Use @code{-filters} to show all the available filters
329 (including also sources and sinks).
331 See also the @option{-filter_complex} option if you want to create filter graphs
332 with multiple inputs and/or outputs.
333 @item -pre[:@var{stream_specifier}] @var{preset_name} (@emph{output,per-stream})
334 Specify the preset for matching stream(s).
336 @item -stats (@emph{global})
337 Print encoding progress/statistics. On by default.
339 @item -attach @var{filename} (@emph{output})
340 Add an attachment to the output file. This is supported by a few formats
341 like Matroska for e.g. fonts used in rendering subtitles. Attachments
342 are implemented as a specific type of stream, so this option will add
343 a new stream to the file. It is then possible to use per-stream options
344 on this stream in the usual way. Attachment streams created with this
345 option will be created after all the other streams (i.e. those created
346 with @code{-map} or automatic mappings).
348 Note that for Matroska you also have to set the mimetype metadata tag:
350 avconv -i INPUT -attach DejaVuSans.ttf -metadata:s:2 mimetype=application/x-truetype-font out.mkv
352 (assuming that the attachment stream will be third in the output file).
354 @item -dump_attachment[:@var{stream_specifier}] @var{filename} (@emph{input,per-stream})
355 Extract the matching attachment stream into a file named @var{filename}. If
356 @var{filename} is empty, then the value of the @code{filename} metadata tag
359 E.g. to extract the first attachment to a file named 'out.ttf':
361 avconv -dump_attachment:t:0 out.ttf INPUT
363 To extract all attachments to files determined by the @code{filename} tag:
365 avconv -dump_attachment:t "" INPUT
368 Technical note -- attachments are implemented as codec extradata, so this
369 option can actually be used to extract extradata from any stream, not just
374 @section Video Options
377 @item -vframes @var{number} (@emph{output})
378 Set the number of video frames to record. This is an alias for @code{-frames:v}.
379 @item -r[:@var{stream_specifier}] @var{fps} (@emph{input/output,per-stream})
380 Set frame rate (Hz value, fraction or abbreviation).
382 As an input option, ignore any timestamps stored in the file and instead
383 generate timestamps assuming constant frame rate @var{fps}.
385 As an output option, duplicate or drop input frames to achieve constant output
386 frame rate @var{fps} (note that this actually causes the @code{fps} filter to be
387 inserted to the end of the corresponding filtergraph).
389 @item -s[:@var{stream_specifier}] @var{size} (@emph{input/output,per-stream})
392 As an input option, this is a shortcut for the @option{video_size} private
393 option, recognized by some demuxers for which the frame size is either not
394 stored in the file or is configurable -- e.g. raw video or video grabbers.
396 As an output option, this inserts the @code{scale} video filter to the
397 @emph{end} of the corresponding filtergraph. Please use the @code{scale} filter
398 directly to insert it at the beginning or some other place.
400 The format is @samp{wxh} (default - same as source). The following
401 abbreviations are recognized:
463 @item -aspect[:@var{stream_specifier}] @var{aspect} (@emph{output,per-stream})
464 Set the video display aspect ratio specified by @var{aspect}.
466 @var{aspect} can be a floating point number string, or a string of the
467 form @var{num}:@var{den}, where @var{num} and @var{den} are the
468 numerator and denominator of the aspect ratio. For example "4:3",
469 "16:9", "1.3333", and "1.7777" are valid argument values.
471 @item -vn (@emph{output})
472 Disable video recording.
474 @item -vcodec @var{codec} (@emph{output})
475 Set the video codec. This is an alias for @code{-codec:v}.
477 Use same quantizer as source (implies VBR).
479 Note that this is NOT SAME QUALITY. Do not use this option unless you know you
482 @item -pass[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
483 Select the pass number (1 or 2). It is used to do two-pass
484 video encoding. The statistics of the video are recorded in the first
485 pass into a log file (see also the option -passlogfile),
486 and in the second pass that log file is used to generate the video
487 at the exact requested bitrate.
488 On pass 1, you may just deactivate audio and set output to null,
489 examples for Windows and Unix:
491 avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y NUL
492 avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null
495 @item -passlogfile[:@var{stream_specifier}] @var{prefix} (@emph{output,per-stream})
496 Set two-pass log file name prefix to @var{prefix}, the default file name
497 prefix is ``av2pass''. The complete file name will be
498 @file{PREFIX-N.log}, where N is a number specific to the output
501 @item -vf @var{filter_graph} (@emph{output})
502 @var{filter_graph} is a description of the filter graph to apply to
504 Use the option "-filters" to show all the available filters (including
505 also sources and sinks). This is an alias for @code{-filter:v}.
509 @section Advanced Video Options
512 @item -pix_fmt[:@var{stream_specifier}] @var{format} (@emph{input/output,per-stream})
513 Set pixel format. Use @code{-pix_fmts} to show all the supported
515 @item -sws_flags @var{flags} (@emph{input/output})
520 @item -rc_override[:@var{stream_specifier}] @var{override} (@emph{output,per-stream})
521 rate control override for specific intervals
524 Deinterlace pictures.
525 This option is deprecated since the deinterlacing is very low quality.
526 Use the yadif filter with @code{-filter:v yadif}.
528 Dump video coding statistics to @file{vstats_HHMMSS.log}.
529 @item -vstats_file @var{file}
530 Dump video coding statistics to @var{file}.
531 @item -top[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
532 top=1/bottom=0/auto=-1 field first
533 @item -dc @var{precision}
535 @item -vtag @var{fourcc/tag} (@emph{output})
536 Force video tag/fourcc. This is an alias for @code{-tag:v}.
537 @item -qphist (@emph{global})
539 @item -force_key_frames[:@var{stream_specifier}] @var{time}[,@var{time}...] (@emph{output,per-stream})
540 Force key frames at the specified timestamps, more precisely at the first
541 frames after each specified time.
542 This option can be useful to ensure that a seek point is present at a
543 chapter mark or any other designated place in the output file.
544 The timestamps must be specified in ascending order.
546 @item -copyinkf[:@var{stream_specifier}] (@emph{output,per-stream})
547 When doing stream copy, copy also non-key frames found at the
551 @section Audio Options
554 @item -aframes @var{number} (@emph{output})
555 Set the number of audio frames to record. This is an alias for @code{-frames:a}.
556 @item -ar[:@var{stream_specifier}] @var{freq} (@emph{input/output,per-stream})
557 Set the audio sampling frequency. For output streams it is set by
558 default to the frequency of the corresponding input stream. For input
559 streams this option only makes sense for audio grabbing devices and raw
560 demuxers and is mapped to the corresponding demuxer options.
561 @item -aq @var{q} (@emph{output})
562 Set the audio quality (codec-specific, VBR). This is an alias for -q:a.
563 @item -ac[:@var{stream_specifier}] @var{channels} (@emph{input/output,per-stream})
564 Set the number of audio channels. For output streams it is set by
565 default to the number of input audio channels. For input streams
566 this option only makes sense for audio grabbing devices and raw demuxers
567 and is mapped to the corresponding demuxer options.
568 @item -an (@emph{output})
569 Disable audio recording.
570 @item -acodec @var{codec} (@emph{input/output})
571 Set the audio codec. This is an alias for @code{-codec:a}.
572 @item -sample_fmt[:@var{stream_specifier}] @var{sample_fmt} (@emph{output,per-stream})
573 Set the audio sample format. Use @code{-sample_fmts} to get a list
574 of supported sample formats.
575 @item -af @var{filter_graph} (@emph{output})
576 @var{filter_graph} is a description of the filter graph to apply to
578 Use the option "-filters" to show all the available filters (including
579 also sources and sinks). This is an alias for @code{-filter:a}.
582 @section Advanced Audio options:
585 @item -atag @var{fourcc/tag} (@emph{output})
586 Force audio tag/fourcc. This is an alias for @code{-tag:a}.
589 @section Subtitle options:
592 @item -scodec @var{codec} (@emph{input/output})
593 Set the subtitle codec. This is an alias for @code{-codec:s}.
594 @item -sn (@emph{output})
595 Disable subtitle recording.
598 @section Advanced options
601 @item -map [-]@var{input_file_id}[:@var{stream_specifier}][,@var{sync_file_id}[:@var{stream_specifier}]] | @var{[linklabel]} (@emph{output})
603 Designate one or more input streams as a source for the output file. Each input
604 stream is identified by the input file index @var{input_file_id} and
605 the input stream index @var{input_stream_id} within the input
606 file. Both indices start at 0. If specified,
607 @var{sync_file_id}:@var{stream_specifier} sets which input stream
608 is used as a presentation sync reference.
610 The first @code{-map} option on the command line specifies the
611 source for output stream 0, the second @code{-map} option specifies
612 the source for output stream 1, etc.
614 A @code{-} character before the stream identifier creates a "negative" mapping.
615 It disables matching streams from already created mappings.
617 An alternative @var{[linklabel]} form will map outputs from complex filter
618 graphs (see the @option{-filter_complex} option) to the output file.
619 @var{linklabel} must correspond to a defined output link label in the graph.
621 For example, to map ALL streams from the first input file to output
623 avconv -i INPUT -map 0 output
626 For example, if you have two audio streams in the first input file,
627 these streams are identified by "0:0" and "0:1". You can use
628 @code{-map} to select which streams to place in an output file. For
631 avconv -i INPUT -map 0:1 out.wav
633 will map the input stream in @file{INPUT} identified by "0:1" to
634 the (single) output stream in @file{out.wav}.
636 For example, to select the stream with index 2 from input file
637 @file{a.mov} (specified by the identifier "0:2"), and stream with
638 index 6 from input @file{b.mov} (specified by the identifier "1:6"),
639 and copy them to the output file @file{out.mov}:
641 avconv -i a.mov -i b.mov -c copy -map 0:2 -map 1:6 out.mov
644 To select all video and the third audio stream from an input file:
646 avconv -i INPUT -map 0:v -map 0:a:2 OUTPUT
649 To map all the streams except the second audio, use negative mappings
651 avconv -i INPUT -map 0 -map -0:a:1 OUTPUT
654 Note that using this option disables the default mappings for this output file.
656 @item -map_metadata[:@var{metadata_spec_out}] @var{infile}[:@var{metadata_spec_in}] (@emph{output,per-metadata})
657 Set metadata information of the next output file from @var{infile}. Note that
658 those are file indices (zero-based), not filenames.
659 Optional @var{metadata_spec_in/out} parameters specify, which metadata to copy.
660 A metadata specifier can have the following forms:
663 global metadata, i.e. metadata that applies to the whole file
665 @item @var{s}[:@var{stream_spec}]
666 per-stream metadata. @var{stream_spec} is a stream specifier as described
667 in the @ref{Stream specifiers} chapter. In an input metadata specifier, the first
668 matching stream is copied from. In an output metadata specifier, all matching
669 streams are copied to.
671 @item @var{c}:@var{chapter_index}
672 per-chapter metadata. @var{chapter_index} is the zero-based chapter index.
674 @item @var{p}:@var{program_index}
675 per-program metadata. @var{program_index} is the zero-based program index.
677 If metadata specifier is omitted, it defaults to global.
679 By default, global metadata is copied from the first input file,
680 per-stream and per-chapter metadata is copied along with streams/chapters. These
681 default mappings are disabled by creating any mapping of the relevant type. A negative
682 file index can be used to create a dummy mapping that just disables automatic copying.
684 For example to copy metadata from the first stream of the input file to global metadata
687 avconv -i in.ogg -map_metadata 0:s:0 out.mp3
690 To do the reverse, i.e. copy global metadata to all audio streams:
692 avconv -i in.mkv -map_metadata:s:a 0:g out.mkv
694 Note that simple @code{0} would work as well in this example, since global
695 metadata is assumed by default.
697 @item -map_chapters @var{input_file_index} (@emph{output})
698 Copy chapters from input file with index @var{input_file_index} to the next
699 output file. If no chapter mapping is specified, then chapters are copied from
700 the first input file with at least one chapter. Use a negative file index to
701 disable any chapter copying.
703 Print specific debug info.
704 @item -benchmark (@emph{global})
705 Show benchmarking information at the end of an encode.
706 Shows CPU time used and maximum memory consumption.
707 Maximum memory consumption is not supported on all systems,
708 it will usually display as 0 if not supported.
709 @item -timelimit @var{duration} (@emph{global})
710 Exit after avconv has been running for @var{duration} seconds.
711 @item -dump (@emph{global})
712 Dump each input packet to stderr.
713 @item -hex (@emph{global})
714 When dumping packets, also dump the payload.
715 @item -re (@emph{input})
716 Read input at native frame rate. Mainly used to simulate a grab device.
717 @item -vsync @var{parameter}
722 Each frame is passed with its timestamp from the demuxer to the muxer.
724 Frames will be duplicated and dropped to achieve exactly the requested
727 Frames are passed through with their timestamp or dropped so as to
728 prevent 2 frames from having the same timestamp.
730 Chooses between 1 and 2 depending on muxer capabilities. This is the
734 With -map you can select from which stream the timestamps should be
735 taken. You can leave either video or audio unchanged and sync the
736 remaining stream(s) to the unchanged one.
738 @item -async @var{samples_per_second}
739 Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
740 the parameter is the maximum samples per second by which the audio is changed.
741 -async 1 is a special case where only the start of the audio stream is corrected
742 without any later correction.
743 This option has been deprecated. Use the @code{asyncts} audio filter instead.
745 Copy timestamps from input to output.
747 Copy input stream time base from input to output when stream copying.
748 @item -shortest (@emph{output})
749 Finish encoding when the shortest input stream ends.
750 @item -dts_delta_threshold
751 Timestamp discontinuity delta threshold.
752 @item -muxdelay @var{seconds} (@emph{input})
753 Set the maximum demux-decode delay.
754 @item -muxpreload @var{seconds} (@emph{input})
755 Set the initial demux-decode delay.
756 @item -streamid @var{output-stream-index}:@var{new-value} (@emph{output})
757 Assign a new stream-id value to an output stream. This option should be
758 specified prior to the output filename to which it applies.
759 For the situation where multiple output files exist, a streamid
760 may be reassigned to a different value.
762 For example, to set the stream 0 PID to 33 and the stream 1 PID to 36 for
763 an output mpegts file:
765 avconv -i infile -streamid 0:33 -streamid 1:36 out.ts
768 @item -bsf[:@var{stream_specifier}] @var{bitstream_filters} (@emph{output,per-stream})
769 Set bitstream filters for matching streams. @var{bistream_filters} is
770 a comma-separated list of bitstream filters. Use the @code{-bsfs} option
771 to get the list of bitstream filters.
773 avconv -i h264.mp4 -c:v copy -bsf:v h264_mp4toannexb -an out.h264
776 avconv -i file.mov -an -vn -bsf:s mov2textsub -c:s copy -f rawvideo sub.txt
779 @item -tag[:@var{stream_specifier}] @var{codec_tag} (@emph{output,per-stream})
780 Force a tag/fourcc for matching streams.
782 @item -cpuflags mask (@emph{global})
783 Set a mask that's applied to autodetected CPU flags. This option is intended
784 for testing. Do not use it unless you know what you're doing.
786 @item -filter_complex @var{filtergraph} (@emph{global})
787 Define a complex filter graph, i.e. one with arbitrary number of inputs and/or
788 outputs. For simple graphs -- those with one input and one output of the same
789 type -- see the @option{-filter} options. @var{filtergraph} is a description of
790 the filter graph, as described in @ref{Filtergraph syntax}.
792 Input link labels must refer to input streams using the
793 @code{[file_index:stream_specifier]} syntax (i.e. the same as @option{-map}
794 uses). If @var{stream_specifier} matches multiple streams, the first one will be
795 used. An unlabeled input will be connected to the first unused input stream of
798 Output link labels are referred to with @option{-map}. Unlabeled outputs are
799 added to the first output file.
801 Note that with this option it is possible to use only lavfi sources without
804 For example, to overlay an image over video
806 avconv -i video.mkv -i image.png -filter_complex '[0:v][1:v]overlay[out]' -map
809 Here @code{[0:v]} refers to the first video stream in the first input file,
810 which is linked to the first (main) input of the overlay filter. Similarly the
811 first video stream in the second input is linked to the second (overlay) input
814 Assuming there is only one video stream in each input file, we can omit input
815 labels, so the above is equivalent to
817 avconv -i video.mkv -i image.png -filter_complex 'overlay[out]' -map
821 Furthermore we can omit the output label and the single output from the filter
822 graph will be added to the output file automatically, so we can simply write
824 avconv -i video.mkv -i image.png -filter_complex 'overlay' out.mkv
827 To generate 5 seconds of pure red video using lavfi @code{color} source:
829 avconv -filter_complex 'color=red' -t 5 out.mkv
839 For streaming at very low bitrate application, use a low frame rate
840 and a small GOP size. This is especially true for RealVideo where
841 the Linux player does not seem to be very fast, so it can miss
842 frames. An example is:
845 avconv -g 3 -r 3 -t 10 -b 50k -s qcif -f rv10 /tmp/b.rm
849 The parameter 'q' which is displayed while encoding is the current
850 quantizer. The value 1 indicates that a very good quality could
851 be achieved. The value 31 indicates the worst quality. If q=31 appears
852 too often, it means that the encoder cannot compress enough to meet
853 your bitrate. You must either increase the bitrate, decrease the
854 frame rate or decrease the frame size.
857 If your computer is not fast enough, you can speed up the
858 compression at the expense of the compression ratio. You can use
859 '-me zero' to speed up motion estimation, and '-g 0' to disable
860 motion estimation completely (you have only I-frames, which means it
861 is about as good as JPEG compression).
864 To have very low audio bitrates, reduce the sampling frequency
865 (down to 22050 Hz for MPEG audio, 22050 or 11025 for AC-3).
868 To have a constant quality (but a variable bitrate), use the option
869 '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
876 @c man begin EXAMPLES
878 @section Preset files
880 A preset file contains a sequence of @var{option=value} pairs, one for
881 each line, specifying a sequence of options which can be specified also on
882 the command line. Lines starting with the hash ('#') character are ignored and
883 are used to provide comments. Empty lines are also ignored. Check the
884 @file{presets} directory in the Libav source tree for examples.
886 Preset files are specified with the @code{pre} option, this option takes a
887 preset name as input. Avconv searches for a file named @var{preset_name}.avpreset in
888 the directories @file{$AVCONV_DATADIR} (if set), and @file{$HOME/.avconv}, and in
889 the data directory defined at configuration time (usually @file{$PREFIX/share/avconv})
890 in that order. For example, if the argument is @code{libx264-max}, it will
891 search for the file @file{libx264-max.avpreset}.
893 @section Video and Audio grabbing
895 If you specify the input format and device then avconv can grab video
899 avconv -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
902 Note that you must activate the right video source and channel before
903 launching avconv with any TV viewer such as
904 @uref{http://linux.bytesex.org/xawtv/, xawtv} by Gerd Knorr. You also
905 have to set the audio recording levels correctly with a
908 @section X11 grabbing
910 Grab the X11 display with avconv via
913 avconv -f x11grab -s cif -r 25 -i :0.0 /tmp/out.mpg
916 0.0 is display.screen number of your X11 server, same as
917 the DISPLAY environment variable.
920 avconv -f x11grab -s cif -r 25 -i :0.0+10,20 /tmp/out.mpg
923 0.0 is display.screen number of your X11 server, same as the DISPLAY environment
924 variable. 10 is the x-offset and 20 the y-offset for the grabbing.
926 @section Video and Audio file format conversion
928 Any supported file format and protocol can serve as input to avconv:
933 You can use YUV files as input:
936 avconv -i /tmp/test%d.Y /tmp/out.mpg
939 It will use the files:
941 /tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
942 /tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
945 The Y files use twice the resolution of the U and V files. They are
946 raw files, without header. They can be generated by all decent video
947 decoders. You must specify the size of the image with the @option{-s} option
948 if avconv cannot guess it.
951 You can input from a raw YUV420P file:
954 avconv -i /tmp/test.yuv /tmp/out.avi
957 test.yuv is a file containing raw YUV planar data. Each frame is composed
958 of the Y plane followed by the U and V planes at half vertical and
959 horizontal resolution.
962 You can output to a raw YUV420P file:
965 avconv -i mydivx.avi hugefile.yuv
969 You can set several input files and output files:
972 avconv -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
975 Converts the audio file a.wav and the raw YUV video file a.yuv
979 You can also do audio and video conversions at the same time:
982 avconv -i /tmp/a.wav -ar 22050 /tmp/a.mp2
985 Converts a.wav to MPEG audio at 22050 Hz sample rate.
988 You can encode to several formats at the same time and define a
989 mapping from input stream to output streams:
992 avconv -i /tmp/a.wav -map 0:a -b 64k /tmp/a.mp2 -map 0:a -b 128k /tmp/b.mp2
995 Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
996 file:index' specifies which input stream is used for each output
997 stream, in the order of the definition of output streams.
1000 You can transcode decrypted VOBs:
1003 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
1006 This is a typical DVD ripping example; the input is a VOB file, the
1007 output an AVI file with MPEG-4 video and MP3 audio. Note that in this
1008 command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
1009 GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
1010 input video. Furthermore, the audio stream is MP3-encoded so you need
1011 to enable LAME support by passing @code{--enable-libmp3lame} to configure.
1012 The mapping is particularly useful for DVD transcoding
1013 to get the desired audio language.
1015 NOTE: To see the supported input formats, use @code{avconv -formats}.
1018 You can extract images from a video, or create a video from many images:
1020 For extracting images from a video:
1022 avconv -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg
1025 This will extract one video frame per second from the video and will
1026 output them in files named @file{foo-001.jpeg}, @file{foo-002.jpeg},
1027 etc. Images will be rescaled to fit the new WxH values.
1029 If you want to extract just a limited number of frames, you can use the
1030 above command in combination with the -vframes or -t option, or in
1031 combination with -ss to start extracting from a certain point in time.
1033 For creating a video from many images:
1035 avconv -f image2 -i foo-%03d.jpeg -r 12 -s WxH foo.avi
1038 The syntax @code{foo-%03d.jpeg} specifies to use a decimal number
1039 composed of three digits padded with zeroes to express the sequence
1040 number. It is the same syntax supported by the C printf function, but
1041 only formats accepting a normal integer are suitable.
1044 You can put many streams of the same type in the output:
1047 avconv -i test1.avi -i test2.avi -map 0.3 -map 0.2 -map 0.1 -map 0.0 -c copy test12.nut
1050 The resulting output file @file{test12.avi} will contain first four streams from
1051 the input file in reverse order.
1054 To force CBR video output:
1056 avconv -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v
1060 The four options lmin, lmax, mblmin and mblmax use 'lambda' units,
1061 but you may use the QP2LAMBDA constant to easily convert from 'q' units:
1063 avconv -i src.ext -lmax 21*QP2LAMBDA dst.ext
1070 @include encoders.texi
1071 @include demuxers.texi
1072 @include muxers.texi
1073 @include indevs.texi
1074 @include outdevs.texi
1075 @include protocols.texi
1076 @include bitstream_filters.texi
1077 @include filters.texi
1078 @include metadata.texi
1083 @settitle avconv video converter
1085 @c man begin SEEALSO
1086 avplay(1), avprobe(1) and the Libav HTML documentation
1089 @c man begin AUTHORS
1090 The Libav developers