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
92 | file | ---------> | packets | -----+
93 |_______| |______________| |
100 ________ ______________ |
102 | output | <-------- | encoded data | <----+
103 | file | muxer | packets | encoder
104 |________| |______________|
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.
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 -
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:
133 _________ ______________
135 | decoded | | encoded data |
136 | frames |\ /| packets |
137 |_________| \ / |______________|
139 simple \ | | / encoder
140 filtergraph \| filtered |/
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:
151 _______ _____________ _______ ________
153 | input | ---> | deinterlace | ---> | scale | ---> | output |
154 |_______| |_____________| |_______| |________|
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:
172 | input 0 |\ __________
174 \ _________ /| output 0 |
176 _________ \| complex | /
178 | input 1 |---->| filter |\
179 |_________| | | \ __________
182 _________ / |_________| |__________|
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.
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:
205 _______ ______________ ________
207 | input | demuxer | encoded data | muxer | output |
208 | file | ---------> | packets | -------> | file |
209 |_______| |______________| |________|
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.
217 @c man end DETAILED DESCRIPTION
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
231 @c man end STREAM SELECTION
236 @include avtools-common-opts.texi
238 @section Main options
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})
250 @item -y (@emph{global})
251 Overwrite output files without asking.
253 @item -n (@emph{global})
254 Immediately exit when output files already exist.
256 @item -loop @var{number} (@emph{input})
257 Set number of times input stream shall be looped. Loop 0 means no loop,
258 loop -1 means infinite loop.
260 @item -c[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
261 @itemx -codec[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
262 Select an encoder (when used before an output file) or a decoder (when used
263 before an input file) for one or more streams. @var{codec} is the name of a
264 decoder/encoder or a special value @code{copy} (output only) to indicate that
265 the stream is not to be reencoded.
269 avconv -i INPUT -map 0 -c:v libx264 -c:a copy OUTPUT
271 encodes all video streams with libx264 and copies all audio streams.
273 For each stream, the last matching @code{c} option is applied, so
275 avconv -i INPUT -map 0 -c copy -c:v:1 libx264 -c:a:137 libvorbis OUTPUT
277 will copy all the streams except the second video, which will be encoded with
278 libx264, and the 138th audio, which will be encoded with libvorbis.
280 @item -t @var{duration} (@emph{output})
281 Stop writing the output after its duration reaches @var{duration}.
282 @var{duration} may be a number in seconds, or in @code{hh:mm:ss[.xxx]} form.
284 @item -fs @var{limit_size} (@emph{output})
285 Set the file size limit.
287 @item -ss @var{position} (@emph{input/output})
288 When used as an input option (before @code{-i}), seeks in this input file to
289 @var{position}. Note the in most formats it is not possible to seek exactly, so
290 @command{avconv} will seek to the closest seek point before @var{position}.
291 When transcoding and @option{-accurate_seek} is enabled (the default), this
292 extra segment between the seek point and @var{position} will be decoded and
293 discarded. When doing stream copy or when @option{-noaccurate_seek} is used, it
296 When used as an output option (before an output filename), decodes but discards
297 input until the timestamps reach @var{position}.
299 @var{position} may be either in seconds or in @code{hh:mm:ss[.xxx]} form.
301 @item -itsoffset @var{offset} (@emph{input})
302 Set the input time offset in seconds.
303 @code{[-]hh:mm:ss[.xxx]} syntax is also supported.
304 The offset is added to the timestamps of the input files.
305 Specifying a positive offset means that the corresponding
306 streams are delayed by @var{offset} seconds.
308 @item -metadata[:metadata_specifier] @var{key}=@var{value} (@emph{output,per-metadata})
309 Set a metadata key/value pair.
311 An optional @var{metadata_specifier} may be given to set metadata
312 on streams or chapters. See @code{-map_metadata} documentation for
315 This option overrides metadata set with @code{-map_metadata}. It is
316 also possible to delete metadata by using an empty value.
318 For example, for setting the title in the output file:
320 avconv -i in.avi -metadata title="my title" out.flv
323 To set the language of the first audio stream:
325 avconv -i INPUT -metadata:s:a:0 language=eng OUTPUT
328 @item -target @var{type} (@emph{output})
329 Specify target file type (@code{vcd}, @code{svcd}, @code{dvd}, @code{dv},
330 @code{dv50}). @var{type} may be prefixed with @code{pal-}, @code{ntsc-} or
331 @code{film-} to use the corresponding standard. All the format options
332 (bitrate, codecs, buffer sizes) are then set automatically. You can just type:
335 avconv -i myfile.avi -target vcd /tmp/vcd.mpg
338 Nevertheless you can specify additional options as long as you know
339 they do not conflict with the standard, as in:
342 avconv -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
345 @item -dframes @var{number} (@emph{output})
346 Set the number of data frames to record. This is an alias for @code{-frames:d}.
348 @item -frames[:@var{stream_specifier}] @var{framecount} (@emph{output,per-stream})
349 Stop writing to the stream after @var{framecount} frames.
351 @item -q[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
352 @itemx -qscale[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
353 Use fixed quality scale (VBR). The meaning of @var{q} is
356 @item -filter[:@var{stream_specifier}] @var{filter_graph} (@emph{output,per-stream})
357 @var{filter_graph} is a description of the filter graph to apply to
358 the stream. Use @code{-filters} to show all the available filters
359 (including also sources and sinks).
361 See also the @option{-filter_complex} option if you want to create filter graphs
362 with multiple inputs and/or outputs.
364 @item -filter_script[:@var{stream_specifier}] @var{filename} (@emph{output,per-stream})
365 This option is similar to @option{-filter}, the only difference is that its
366 argument is the name of the file from which a filtergraph description is to be
369 @item -pre[:@var{stream_specifier}] @var{preset_name} (@emph{output,per-stream})
370 Specify the preset for matching stream(s).
372 @item -stats (@emph{global})
373 Print encoding progress/statistics. On by default.
375 @item -attach @var{filename} (@emph{output})
376 Add an attachment to the output file. This is supported by a few formats
377 like Matroska for e.g. fonts used in rendering subtitles. Attachments
378 are implemented as a specific type of stream, so this option will add
379 a new stream to the file. It is then possible to use per-stream options
380 on this stream in the usual way. Attachment streams created with this
381 option will be created after all the other streams (i.e. those created
382 with @code{-map} or automatic mappings).
384 Note that for Matroska you also have to set the mimetype metadata tag:
386 avconv -i INPUT -attach DejaVuSans.ttf -metadata:s:2 mimetype=application/x-truetype-font out.mkv
388 (assuming that the attachment stream will be third in the output file).
390 @item -dump_attachment[:@var{stream_specifier}] @var{filename} (@emph{input,per-stream})
391 Extract the matching attachment stream into a file named @var{filename}. If
392 @var{filename} is empty, then the value of the @code{filename} metadata tag
395 E.g. to extract the first attachment to a file named 'out.ttf':
397 avconv -dump_attachment:t:0 out.ttf INPUT
399 To extract all attachments to files determined by the @code{filename} tag:
401 avconv -dump_attachment:t "" INPUT
404 Technical note -- attachments are implemented as codec extradata, so this
405 option can actually be used to extract extradata from any stream, not just
409 Disable automatically rotating video based on file metadata.
413 @section Video Options
416 @item -vframes @var{number} (@emph{output})
417 Set the number of video frames to record. This is an alias for @code{-frames:v}.
418 @item -r[:@var{stream_specifier}] @var{fps} (@emph{input/output,per-stream})
419 Set frame rate (Hz value, fraction or abbreviation).
421 As an input option, ignore any timestamps stored in the file and instead
422 generate timestamps assuming constant frame rate @var{fps}.
424 As an output option, duplicate or drop input frames to achieve constant output
425 frame rate @var{fps} (note that this actually causes the @code{fps} filter to be
426 inserted to the end of the corresponding filtergraph).
428 @item -s[:@var{stream_specifier}] @var{size} (@emph{input/output,per-stream})
431 As an input option, this is a shortcut for the @option{video_size} private
432 option, recognized by some demuxers for which the frame size is either not
433 stored in the file or is configurable -- e.g. raw video or video grabbers.
435 As an output option, this inserts the @code{scale} video filter to the
436 @emph{end} of the corresponding filtergraph. Please use the @code{scale} filter
437 directly to insert it at the beginning or some other place.
439 The format is @samp{wxh} (default - same as source). The following
440 abbreviations are recognized:
510 @item -aspect[:@var{stream_specifier}] @var{aspect} (@emph{output,per-stream})
511 Set the video display aspect ratio specified by @var{aspect}.
513 @var{aspect} can be a floating point number string, or a string of the
514 form @var{num}:@var{den}, where @var{num} and @var{den} are the
515 numerator and denominator of the aspect ratio. For example "4:3",
516 "16:9", "1.3333", and "1.7777" are valid argument values.
518 @item -vn (@emph{output})
519 Disable video recording.
521 @item -vcodec @var{codec} (@emph{output})
522 Set the video codec. This is an alias for @code{-codec:v}.
524 @item -pass[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
525 Select the pass number (1 or 2). It is used to do two-pass
526 video encoding. The statistics of the video are recorded in the first
527 pass into a log file (see also the option -passlogfile),
528 and in the second pass that log file is used to generate the video
529 at the exact requested bitrate.
530 On pass 1, you may just deactivate audio and set output to null,
531 examples for Windows and Unix:
533 avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y NUL
534 avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null
537 @item -passlogfile[:@var{stream_specifier}] @var{prefix} (@emph{output,per-stream})
538 Set two-pass log file name prefix to @var{prefix}, the default file name
539 prefix is ``av2pass''. The complete file name will be
540 @file{PREFIX-N.log}, where N is a number specific to the output
543 @item -vf @var{filter_graph} (@emph{output})
544 @var{filter_graph} is a description of the filter graph to apply to
546 Use the option "-filters" to show all the available filters (including
547 also sources and sinks). This is an alias for @code{-filter:v}.
551 @section Advanced Video Options
554 @item -pix_fmt[:@var{stream_specifier}] @var{format} (@emph{input/output,per-stream})
555 Set pixel format. Use @code{-pix_fmts} to show all the supported
557 @item -sws_flags @var{flags} (@emph{input/output})
562 @item -rc_override[:@var{stream_specifier}] @var{override} (@emph{output,per-stream})
563 rate control override for specific intervals
566 Dump video coding statistics to @file{vstats_HHMMSS.log}.
567 @item -vstats_file @var{file}
568 Dump video coding statistics to @var{file}.
569 @item -top[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
570 top=1/bottom=0/auto=-1 field first
571 @item -dc @var{precision}
573 @item -vtag @var{fourcc/tag} (@emph{output})
574 Force video tag/fourcc. This is an alias for @code{-tag:v}.
575 @item -qphist (@emph{global})
577 @item -force_key_frames[:@var{stream_specifier}] @var{time}[,@var{time}...] (@emph{output,per-stream})
578 Force key frames at the specified timestamps, more precisely at the first
579 frames after each specified time.
580 This option can be useful to ensure that a seek point is present at a
581 chapter mark or any other designated place in the output file.
582 The timestamps must be specified in ascending order.
584 @item -copyinkf[:@var{stream_specifier}] (@emph{output,per-stream})
585 When doing stream copy, copy also non-key frames found at the
588 @item -hwaccel[:@var{stream_specifier}] @var{hwaccel} (@emph{input,per-stream})
589 Use hardware acceleration to decode the matching stream(s). The allowed values
590 of @var{hwaccel} are:
593 Do not use any hardware acceleration (the default).
596 Automatically select the hardware acceleration method.
599 Use Apple VDA hardware acceleration.
602 Use VDPAU (Video Decode and Presentation API for Unix) hardware acceleration.
605 Use DXVA2 (DirectX Video Acceleration) hardware acceleration.
608 Use the Intel QuickSync Video acceleration for video transcoding.
610 Unlike most other values, this option does not enable accelerated decoding (that
611 is used automatically whenever a qsv decoder is selected), but accelerated
612 transcoding, without copying the frames into the system memory.
614 For it to work, both the decoder and the encoder must support QSV acceleration
615 and no filters must be used.
618 This option has no effect if the selected hwaccel is not available or not
619 supported by the chosen decoder.
621 Note that most acceleration methods are intended for playback and will not be
622 faster than software decoding on modern CPUs. Additionally, @command{avconv}
623 will usually need to copy the decoded frames from the GPU memory into the system
624 memory, resulting in further performance loss. This option is thus mainly
627 @item -hwaccel_device[:@var{stream_specifier}] @var{hwaccel_device} (@emph{input,per-stream})
628 Select a device to use for hardware acceleration.
630 This option only makes sense when the @option{-hwaccel} option is also
631 specified. Its exact meaning depends on the specific hardware acceleration
636 For VDPAU, this option specifies the X11 display/screen to use. If this option
637 is not specified, the value of the @var{DISPLAY} environment variable is used
640 For DXVA2, this option should contain the number of the display adapter to use.
641 If this option is not specified, the default adapter is used.
644 For QSV, this option corresponds to the values of MFX_IMPL_* . Allowed values
659 List all hardware acceleration methods supported in this build of avconv.
663 @section Audio Options
666 @item -aframes @var{number} (@emph{output})
667 Set the number of audio frames to record. This is an alias for @code{-frames:a}.
668 @item -ar[:@var{stream_specifier}] @var{freq} (@emph{input/output,per-stream})
669 Set the audio sampling frequency. For output streams it is set by
670 default to the frequency of the corresponding input stream. For input
671 streams this option only makes sense for audio grabbing devices and raw
672 demuxers and is mapped to the corresponding demuxer options.
673 @item -aq @var{q} (@emph{output})
674 Set the audio quality (codec-specific, VBR). This is an alias for -q:a.
675 @item -ac[:@var{stream_specifier}] @var{channels} (@emph{input/output,per-stream})
676 Set the number of audio channels. For output streams it is set by
677 default to the number of input audio channels. For input streams
678 this option only makes sense for audio grabbing devices and raw demuxers
679 and is mapped to the corresponding demuxer options.
680 @item -an (@emph{output})
681 Disable audio recording.
682 @item -acodec @var{codec} (@emph{input/output})
683 Set the audio codec. This is an alias for @code{-codec:a}.
684 @item -sample_fmt[:@var{stream_specifier}] @var{sample_fmt} (@emph{output,per-stream})
685 Set the audio sample format. Use @code{-sample_fmts} to get a list
686 of supported sample formats.
687 @item -af @var{filter_graph} (@emph{output})
688 @var{filter_graph} is a description of the filter graph to apply to
690 Use the option "-filters" to show all the available filters (including
691 also sources and sinks). This is an alias for @code{-filter:a}.
694 @section Advanced Audio options:
697 @item -atag @var{fourcc/tag} (@emph{output})
698 Force audio tag/fourcc. This is an alias for @code{-tag:a}.
701 @section Subtitle options:
704 @item -scodec @var{codec} (@emph{input/output})
705 Set the subtitle codec. This is an alias for @code{-codec:s}.
706 @item -sn (@emph{output})
707 Disable subtitle recording.
710 @section Advanced options
713 @item -map [-]@var{input_file_id}[:@var{stream_specifier}][,@var{sync_file_id}[:@var{stream_specifier}]] | @var{[linklabel]} (@emph{output})
715 Designate one or more input streams as a source for the output file. Each input
716 stream is identified by the input file index @var{input_file_id} and
717 the input stream index @var{input_stream_id} within the input
718 file. Both indices start at 0. If specified,
719 @var{sync_file_id}:@var{stream_specifier} sets which input stream
720 is used as a presentation sync reference.
722 The first @code{-map} option on the command line specifies the
723 source for output stream 0, the second @code{-map} option specifies
724 the source for output stream 1, etc.
726 A @code{-} character before the stream identifier creates a "negative" mapping.
727 It disables matching streams from already created mappings.
729 An alternative @var{[linklabel]} form will map outputs from complex filter
730 graphs (see the @option{-filter_complex} option) to the output file.
731 @var{linklabel} must correspond to a defined output link label in the graph.
733 For example, to map ALL streams from the first input file to output
735 avconv -i INPUT -map 0 output
738 For example, if you have two audio streams in the first input file,
739 these streams are identified by "0:0" and "0:1". You can use
740 @code{-map} to select which streams to place in an output file. For
743 avconv -i INPUT -map 0:1 out.wav
745 will map the input stream in @file{INPUT} identified by "0:1" to
746 the (single) output stream in @file{out.wav}.
748 For example, to select the stream with index 2 from input file
749 @file{a.mov} (specified by the identifier "0:2"), and stream with
750 index 6 from input @file{b.mov} (specified by the identifier "1:6"),
751 and copy them to the output file @file{out.mov}:
753 avconv -i a.mov -i b.mov -c copy -map 0:2 -map 1:6 out.mov
756 To select all video and the third audio stream from an input file:
758 avconv -i INPUT -map 0:v -map 0:a:2 OUTPUT
761 To map all the streams except the second audio, use negative mappings
763 avconv -i INPUT -map 0 -map -0:a:1 OUTPUT
766 To pick the English audio stream:
768 avconv -i INPUT -map 0:m:language:eng OUTPUT
771 Note that using this option disables the default mappings for this output file.
773 @item -map_metadata[:@var{metadata_spec_out}] @var{infile}[:@var{metadata_spec_in}] (@emph{output,per-metadata})
774 Set metadata information of the next output file from @var{infile}. Note that
775 those are file indices (zero-based), not filenames.
776 Optional @var{metadata_spec_in/out} parameters specify, which metadata to copy.
777 A metadata specifier can have the following forms:
780 global metadata, i.e. metadata that applies to the whole file
782 @item @var{s}[:@var{stream_spec}]
783 per-stream metadata. @var{stream_spec} is a stream specifier as described
784 in the @ref{Stream specifiers} chapter. In an input metadata specifier, the first
785 matching stream is copied from. In an output metadata specifier, all matching
786 streams are copied to.
788 @item @var{c}:@var{chapter_index}
789 per-chapter metadata. @var{chapter_index} is the zero-based chapter index.
791 @item @var{p}:@var{program_index}
792 per-program metadata. @var{program_index} is the zero-based program index.
794 If metadata specifier is omitted, it defaults to global.
796 By default, global metadata is copied from the first input file,
797 per-stream and per-chapter metadata is copied along with streams/chapters. These
798 default mappings are disabled by creating any mapping of the relevant type. A negative
799 file index can be used to create a dummy mapping that just disables automatic copying.
801 For example to copy metadata from the first stream of the input file to global metadata
804 avconv -i in.ogg -map_metadata 0:s:0 out.mp3
807 To do the reverse, i.e. copy global metadata to all audio streams:
809 avconv -i in.mkv -map_metadata:s:a 0:g out.mkv
811 Note that simple @code{0} would work as well in this example, since global
812 metadata is assumed by default.
814 @item -map_chapters @var{input_file_index} (@emph{output})
815 Copy chapters from input file with index @var{input_file_index} to the next
816 output file. If no chapter mapping is specified, then chapters are copied from
817 the first input file with at least one chapter. Use a negative file index to
818 disable any chapter copying.
820 Print specific debug info.
821 @item -benchmark (@emph{global})
822 Show benchmarking information at the end of an encode.
823 Shows CPU time used and maximum memory consumption.
824 Maximum memory consumption is not supported on all systems,
825 it will usually display as 0 if not supported.
826 @item -timelimit @var{duration} (@emph{global})
827 Exit after avconv has been running for @var{duration} seconds.
828 @item -dump (@emph{global})
829 Dump each input packet to stderr.
830 @item -hex (@emph{global})
831 When dumping packets, also dump the payload.
832 @item -re (@emph{input})
833 Read input at native frame rate. Mainly used to simulate a grab device
834 or live input stream (e.g. when reading from a file). Should not be used
835 with actual grab devices or live input streams (where it can cause packet
837 @item -vsync @var{parameter}
842 Each frame is passed with its timestamp from the demuxer to the muxer.
844 Frames will be duplicated and dropped to achieve exactly the requested
847 Frames are passed through with their timestamp or dropped so as to
848 prevent 2 frames from having the same timestamp.
850 Chooses between 1 and 2 depending on muxer capabilities. This is the
854 With -map you can select from which stream the timestamps should be
855 taken. You can leave either video or audio unchanged and sync the
856 remaining stream(s) to the unchanged one.
858 @item -async @var{samples_per_second}
859 Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
860 the parameter is the maximum samples per second by which the audio is changed.
861 -async 1 is a special case where only the start of the audio stream is corrected
862 without any later correction.
863 This option has been deprecated. Use the @code{asyncts} audio filter instead.
865 Copy timestamps from input to output.
867 Copy input stream time base from input to output when stream copying.
868 @item -shortest (@emph{output})
869 Finish encoding when the shortest input stream ends.
870 @item -dts_delta_threshold
871 Timestamp discontinuity delta threshold.
872 @item -muxdelay @var{seconds} (@emph{input})
873 Set the maximum demux-decode delay.
874 @item -muxpreload @var{seconds} (@emph{input})
875 Set the initial demux-decode delay.
876 @item -streamid @var{output-stream-index}:@var{new-value} (@emph{output})
877 Assign a new stream-id value to an output stream. This option should be
878 specified prior to the output filename to which it applies.
879 For the situation where multiple output files exist, a streamid
880 may be reassigned to a different value.
882 For example, to set the stream 0 PID to 33 and the stream 1 PID to 36 for
883 an output mpegts file:
885 avconv -i infile -streamid 0:33 -streamid 1:36 out.ts
888 @item -bsf[:@var{stream_specifier}] @var{bitstream_filters} (@emph{output,per-stream})
889 Set bitstream filters for matching streams. @var{bitstream_filters} is
890 a comma-separated list of bitstream filters. Use the @code{-bsfs} option
891 to get the list of bitstream filters.
893 avconv -i h264.mp4 -c:v copy -bsf:v h264_mp4toannexb -an out.h264
896 avconv -i file.mov -an -vn -bsf:s mov2textsub -c:s copy -f rawvideo sub.txt
899 @item -tag[:@var{stream_specifier}] @var{codec_tag} (@emph{input/output,per-stream})
900 Force a tag/fourcc for matching streams.
902 @item -filter_complex @var{filtergraph} (@emph{global})
903 Define a complex filter graph, i.e. one with arbitrary number of inputs and/or
904 outputs. For simple graphs -- those with one input and one output of the same
905 type -- see the @option{-filter} options. @var{filtergraph} is a description of
906 the filter graph, as described in @ref{Filtergraph syntax}.
908 Input link labels must refer to input streams using the
909 @code{[file_index:stream_specifier]} syntax (i.e. the same as @option{-map}
910 uses). If @var{stream_specifier} matches multiple streams, the first one will be
911 used. An unlabeled input will be connected to the first unused input stream of
914 Output link labels are referred to with @option{-map}. Unlabeled outputs are
915 added to the first output file.
917 Note that with this option it is possible to use only lavfi sources without
920 For example, to overlay an image over video
922 avconv -i video.mkv -i image.png -filter_complex '[0:v][1:v]overlay[out]' -map
925 Here @code{[0:v]} refers to the first video stream in the first input file,
926 which is linked to the first (main) input of the overlay filter. Similarly the
927 first video stream in the second input is linked to the second (overlay) input
930 Assuming there is only one video stream in each input file, we can omit input
931 labels, so the above is equivalent to
933 avconv -i video.mkv -i image.png -filter_complex 'overlay[out]' -map
937 Furthermore we can omit the output label and the single output from the filter
938 graph will be added to the output file automatically, so we can simply write
940 avconv -i video.mkv -i image.png -filter_complex 'overlay' out.mkv
943 To generate 5 seconds of pure red video using lavfi @code{color} source:
945 avconv -filter_complex 'color=red' -t 5 out.mkv
948 @item -filter_complex_script @var{filename} (@emph{global})
949 This option is similar to @option{-filter_complex}, the only difference is that
950 its argument is the name of the file from which a complex filtergraph
951 description is to be read.
953 @item -accurate_seek (@emph{input})
954 This option enables or disables accurate seeking in input files with the
955 @option{-ss} option. It is enabled by default, so seeking is accurate when
956 transcoding. Use @option{-noaccurate_seek} to disable it, which may be useful
957 e.g. when copying some streams and transcoding the others.
967 For streaming at very low bitrate application, use a low frame rate
968 and a small GOP size. This is especially true for RealVideo where
969 the Linux player does not seem to be very fast, so it can miss
970 frames. An example is:
973 avconv -g 3 -r 3 -t 10 -b 50k -s qcif -f rv10 /tmp/b.rm
977 The parameter 'q' which is displayed while encoding is the current
978 quantizer. The value 1 indicates that a very good quality could
979 be achieved. The value 31 indicates the worst quality. If q=31 appears
980 too often, it means that the encoder cannot compress enough to meet
981 your bitrate. You must either increase the bitrate, decrease the
982 frame rate or decrease the frame size.
985 If your computer is not fast enough, you can speed up the
986 compression at the expense of the compression ratio. You can use
987 '-me zero' to speed up motion estimation, and '-g 0' to disable
988 motion estimation completely (you have only I-frames, which means it
989 is about as good as JPEG compression).
992 To have very low audio bitrates, reduce the sampling frequency
993 (down to 22050 Hz for MPEG audio, 22050 or 11025 for AC-3).
996 To have a constant quality (but a variable bitrate), use the option
997 '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
1004 @c man begin EXAMPLES
1006 @section Preset files
1008 A preset file contains a sequence of @var{option=value} pairs, one for
1009 each line, specifying a sequence of options which can be specified also on
1010 the command line. Lines starting with the hash ('#') character are ignored and
1011 are used to provide comments. Empty lines are also ignored. Check the
1012 @file{presets} directory in the Libav source tree for examples.
1014 Preset files are specified with the @code{pre} option, this option takes a
1015 preset name as input. Avconv searches for a file named @var{preset_name}.avpreset in
1016 the directories @file{$AVCONV_DATADIR} (if set), and @file{$HOME/.avconv}, and in
1017 the data directory defined at configuration time (usually @file{$PREFIX/share/avconv})
1018 in that order. For example, if the argument is @code{libx264-max}, it will
1019 search for the file @file{libx264-max.avpreset}.
1021 @section Video and Audio grabbing
1023 If you specify the input format and device then avconv can grab video
1027 avconv -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
1030 Note that you must activate the right video source and channel before
1031 launching avconv with any TV viewer such as
1032 @uref{http://linux.bytesex.org/xawtv/, xawtv} by Gerd Knorr. You also
1033 have to set the audio recording levels correctly with a
1036 @section X11 grabbing
1038 Grab the X11 display with avconv via
1041 avconv -f x11grab -s cif -r 25 -i :0.0 /tmp/out.mpg
1044 0.0 is display.screen number of your X11 server, same as
1045 the DISPLAY environment variable.
1048 avconv -f x11grab -s cif -r 25 -i :0.0+10,20 /tmp/out.mpg
1051 0.0 is display.screen number of your X11 server, same as the DISPLAY environment
1052 variable. 10 is the x-offset and 20 the y-offset for the grabbing.
1054 @section Video and Audio file format conversion
1056 Any supported file format and protocol can serve as input to avconv:
1061 You can use YUV files as input:
1064 avconv -i /tmp/test%d.Y /tmp/out.mpg
1067 It will use the files:
1069 /tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
1070 /tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
1073 The Y files use twice the resolution of the U and V files. They are
1074 raw files, without header. They can be generated by all decent video
1075 decoders. You must specify the size of the image with the @option{-s} option
1076 if avconv cannot guess it.
1079 You can input from a raw YUV420P file:
1082 avconv -i /tmp/test.yuv /tmp/out.avi
1085 test.yuv is a file containing raw YUV planar data. Each frame is composed
1086 of the Y plane followed by the U and V planes at half vertical and
1087 horizontal resolution.
1090 You can output to a raw YUV420P file:
1093 avconv -i mydivx.avi hugefile.yuv
1097 You can set several input files and output files:
1100 avconv -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
1103 Converts the audio file a.wav and the raw YUV video file a.yuv
1107 You can also do audio and video conversions at the same time:
1110 avconv -i /tmp/a.wav -ar 22050 /tmp/a.mp2
1113 Converts a.wav to MPEG audio at 22050 Hz sample rate.
1116 You can encode to several formats at the same time and define a
1117 mapping from input stream to output streams:
1120 avconv -i /tmp/a.wav -map 0:a -b 64k /tmp/a.mp2 -map 0:a -b 128k /tmp/b.mp2
1123 Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
1124 file:index' specifies which input stream is used for each output
1125 stream, in the order of the definition of output streams.
1128 You can transcode decrypted VOBs:
1131 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
1134 This is a typical DVD ripping example; the input is a VOB file, the
1135 output an AVI file with MPEG-4 video and MP3 audio. Note that in this
1136 command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
1137 GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
1138 input video. Furthermore, the audio stream is MP3-encoded so you need
1139 to enable LAME support by passing @code{--enable-libmp3lame} to configure.
1140 The mapping is particularly useful for DVD transcoding
1141 to get the desired audio language.
1143 NOTE: To see the supported input formats, use @code{avconv -formats}.
1146 You can extract images from a video, or create a video from many images:
1148 For extracting images from a video:
1150 avconv -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg
1153 This will extract one video frame per second from the video and will
1154 output them in files named @file{foo-001.jpeg}, @file{foo-002.jpeg},
1155 etc. Images will be rescaled to fit the new WxH values.
1157 If you want to extract just a limited number of frames, you can use the
1158 above command in combination with the -vframes or -t option, or in
1159 combination with -ss to start extracting from a certain point in time.
1161 For creating a video from many images:
1163 avconv -f image2 -i foo-%03d.jpeg -r 12 -s WxH foo.avi
1166 The syntax @code{foo-%03d.jpeg} specifies to use a decimal number
1167 composed of three digits padded with zeroes to express the sequence
1168 number. It is the same syntax supported by the C printf function, but
1169 only formats accepting a normal integer are suitable.
1172 You can put many streams of the same type in the output:
1175 avconv -i test1.avi -i test2.avi -map 1:1 -map 1:0 -map 0:1 -map 0:0 -c copy -y test12.nut
1178 The resulting output file @file{test12.nut} will contain the first four streams
1179 from the input files in reverse order.
1182 To force CBR video output:
1184 avconv -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v
1188 The four options lmin, lmax, mblmin and mblmax use 'lambda' units,
1189 but you may use the QP2LAMBDA constant to easily convert from 'q' units:
1191 avconv -i src.ext -lmax 21*QP2LAMBDA dst.ext
1198 @include decoders.texi
1199 @include encoders.texi
1200 @include demuxers.texi
1201 @include muxers.texi
1202 @include indevs.texi
1203 @include outdevs.texi
1204 @include protocols.texi
1205 @include bitstream_filters.texi
1206 @include filters.texi
1207 @include metadata.texi
1212 @settitle avconv video converter
1214 @c man begin SEEALSO
1215 avplay(1), avprobe(1) and the Libav HTML documentation
1218 @c man begin AUTHORS
1219 The Libav developers