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.
259 @item -c[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
260 @itemx -codec[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
261 Select an encoder (when used before an output file) or a decoder (when used
262 before an input file) for one or more streams. @var{codec} is the name of a
263 decoder/encoder or a special value @code{copy} (output only) to indicate that
264 the stream is not to be reencoded.
268 avconv -i INPUT -map 0 -c:v libx264 -c:a copy OUTPUT
270 encodes all video streams with libx264 and copies all audio streams.
272 For each stream, the last matching @code{c} option is applied, so
274 avconv -i INPUT -map 0 -c copy -c:v:1 libx264 -c:a:137 libvorbis OUTPUT
276 will copy all the streams except the second video, which will be encoded with
277 libx264, and the 138th audio, which will be encoded with libvorbis.
279 @item -t @var{duration} (@emph{output})
280 Stop writing the output after its duration reaches @var{duration}.
281 @var{duration} may be a number in seconds, or in @code{hh:mm:ss[.xxx]} form.
283 @item -fs @var{limit_size} (@emph{output})
284 Set the file size limit.
286 @item -ss @var{position} (@emph{input/output})
287 When used as an input option (before @code{-i}), seeks in this input file to
288 @var{position}. Note the in most formats it is not possible to seek exactly, so
289 @command{avconv} will seek to the closest seek point before @var{position}.
290 When transcoding and @option{-accurate_seek} is enabled (the default), this
291 extra segment between the seek point and @var{position} will be decoded and
292 discarded. When doing stream copy or when @option{-noaccurate_seek} is used, it
295 When used as an output option (before an output filename), decodes but discards
296 input until the timestamps reach @var{position}.
298 @var{position} may be either in seconds or in @code{hh:mm:ss[.xxx]} form.
300 @item -itsoffset @var{offset} (@emph{input})
301 Set the input time offset in seconds.
302 @code{[-]hh:mm:ss[.xxx]} syntax is also supported.
303 The offset is added to the timestamps of the input files.
304 Specifying a positive offset means that the corresponding
305 streams are delayed by @var{offset} seconds.
307 @item -metadata[:metadata_specifier] @var{key}=@var{value} (@emph{output,per-metadata})
308 Set a metadata key/value pair.
310 An optional @var{metadata_specifier} may be given to set metadata
311 on streams or chapters. See @code{-map_metadata} documentation for
314 This option overrides metadata set with @code{-map_metadata}. It is
315 also possible to delete metadata by using an empty value.
317 For example, for setting the title in the output file:
319 avconv -i in.avi -metadata title="my title" out.flv
322 To set the language of the first audio stream:
324 avconv -i INPUT -metadata:s:a:0 language=eng OUTPUT
327 @item -target @var{type} (@emph{output})
328 Specify target file type (@code{vcd}, @code{svcd}, @code{dvd}, @code{dv},
329 @code{dv50}). @var{type} may be prefixed with @code{pal-}, @code{ntsc-} or
330 @code{film-} to use the corresponding standard. All the format options
331 (bitrate, codecs, buffer sizes) are then set automatically. You can just type:
334 avconv -i myfile.avi -target vcd /tmp/vcd.mpg
337 Nevertheless you can specify additional options as long as you know
338 they do not conflict with the standard, as in:
341 avconv -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
344 @item -dframes @var{number} (@emph{output})
345 Set the number of data frames to record. This is an alias for @code{-frames:d}.
347 @item -frames[:@var{stream_specifier}] @var{framecount} (@emph{output,per-stream})
348 Stop writing to the stream after @var{framecount} frames.
350 @item -q[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
351 @itemx -qscale[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
352 Use fixed quality scale (VBR). The meaning of @var{q} is
355 @item -filter[:@var{stream_specifier}] @var{filter_graph} (@emph{output,per-stream})
356 @var{filter_graph} is a description of the filter graph to apply to
357 the stream. Use @code{-filters} to show all the available filters
358 (including also sources and sinks).
360 See also the @option{-filter_complex} option if you want to create filter graphs
361 with multiple inputs and/or outputs.
363 @item -filter_script[:@var{stream_specifier}] @var{filename} (@emph{output,per-stream})
364 This option is similar to @option{-filter}, the only difference is that its
365 argument is the name of the file from which a filtergraph description is to be
368 @item -pre[:@var{stream_specifier}] @var{preset_name} (@emph{output,per-stream})
369 Specify the preset for matching stream(s).
371 @item -stats (@emph{global})
372 Print encoding progress/statistics. On by default.
374 @item -attach @var{filename} (@emph{output})
375 Add an attachment to the output file. This is supported by a few formats
376 like Matroska for e.g. fonts used in rendering subtitles. Attachments
377 are implemented as a specific type of stream, so this option will add
378 a new stream to the file. It is then possible to use per-stream options
379 on this stream in the usual way. Attachment streams created with this
380 option will be created after all the other streams (i.e. those created
381 with @code{-map} or automatic mappings).
383 Note that for Matroska you also have to set the mimetype metadata tag:
385 avconv -i INPUT -attach DejaVuSans.ttf -metadata:s:2 mimetype=application/x-truetype-font out.mkv
387 (assuming that the attachment stream will be third in the output file).
389 @item -dump_attachment[:@var{stream_specifier}] @var{filename} (@emph{input,per-stream})
390 Extract the matching attachment stream into a file named @var{filename}. If
391 @var{filename} is empty, then the value of the @code{filename} metadata tag
394 E.g. to extract the first attachment to a file named 'out.ttf':
396 avconv -dump_attachment:t:0 out.ttf INPUT
398 To extract all attachments to files determined by the @code{filename} tag:
400 avconv -dump_attachment:t "" INPUT
403 Technical note -- attachments are implemented as codec extradata, so this
404 option can actually be used to extract extradata from any stream, not just
408 Disable automatically rotating video based on file metadata.
412 @section Video Options
415 @item -vframes @var{number} (@emph{output})
416 Set the number of video frames to record. This is an alias for @code{-frames:v}.
417 @item -r[:@var{stream_specifier}] @var{fps} (@emph{input/output,per-stream})
418 Set frame rate (Hz value, fraction or abbreviation).
420 As an input option, ignore any timestamps stored in the file and instead
421 generate timestamps assuming constant frame rate @var{fps}.
423 As an output option, duplicate or drop input frames to achieve constant output
424 frame rate @var{fps} (note that this actually causes the @code{fps} filter to be
425 inserted to the end of the corresponding filtergraph).
427 @item -s[:@var{stream_specifier}] @var{size} (@emph{input/output,per-stream})
430 As an input option, this is a shortcut for the @option{video_size} private
431 option, recognized by some demuxers for which the frame size is either not
432 stored in the file or is configurable -- e.g. raw video or video grabbers.
434 As an output option, this inserts the @code{scale} video filter to the
435 @emph{end} of the corresponding filtergraph. Please use the @code{scale} filter
436 directly to insert it at the beginning or some other place.
438 The format is @samp{wxh} (default - same as source). The following
439 abbreviations are recognized:
509 @item -aspect[:@var{stream_specifier}] @var{aspect} (@emph{output,per-stream})
510 Set the video display aspect ratio specified by @var{aspect}.
512 @var{aspect} can be a floating point number string, or a string of the
513 form @var{num}:@var{den}, where @var{num} and @var{den} are the
514 numerator and denominator of the aspect ratio. For example "4:3",
515 "16:9", "1.3333", and "1.7777" are valid argument values.
517 @item -vn (@emph{output})
518 Disable video recording.
520 @item -vcodec @var{codec} (@emph{output})
521 Set the video codec. This is an alias for @code{-codec:v}.
523 @item -pass[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
524 Select the pass number (1 or 2). It is used to do two-pass
525 video encoding. The statistics of the video are recorded in the first
526 pass into a log file (see also the option -passlogfile),
527 and in the second pass that log file is used to generate the video
528 at the exact requested bitrate.
529 On pass 1, you may just deactivate audio and set output to null,
530 examples for Windows and Unix:
532 avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y NUL
533 avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null
536 @item -passlogfile[:@var{stream_specifier}] @var{prefix} (@emph{output,per-stream})
537 Set two-pass log file name prefix to @var{prefix}, the default file name
538 prefix is ``av2pass''. The complete file name will be
539 @file{PREFIX-N.log}, where N is a number specific to the output
542 @item -vf @var{filter_graph} (@emph{output})
543 @var{filter_graph} is a description of the filter graph to apply to
545 Use the option "-filters" to show all the available filters (including
546 also sources and sinks). This is an alias for @code{-filter:v}.
550 @section Advanced Video Options
553 @item -pix_fmt[:@var{stream_specifier}] @var{format} (@emph{input/output,per-stream})
554 Set pixel format. Use @code{-pix_fmts} to show all the supported
556 @item -sws_flags @var{flags} (@emph{input/output})
561 @item -rc_override[:@var{stream_specifier}] @var{override} (@emph{output,per-stream})
562 rate control override for specific intervals
565 Dump video coding statistics to @file{vstats_HHMMSS.log}.
566 @item -vstats_file @var{file}
567 Dump video coding statistics to @var{file}.
568 @item -top[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
569 top=1/bottom=0/auto=-1 field first
570 @item -dc @var{precision}
572 @item -vtag @var{fourcc/tag} (@emph{output})
573 Force video tag/fourcc. This is an alias for @code{-tag:v}.
574 @item -qphist (@emph{global})
576 @item -force_key_frames[:@var{stream_specifier}] @var{time}[,@var{time}...] (@emph{output,per-stream})
577 Force key frames at the specified timestamps, more precisely at the first
578 frames after each specified time.
579 This option can be useful to ensure that a seek point is present at a
580 chapter mark or any other designated place in the output file.
581 The timestamps must be specified in ascending order.
583 @item -copyinkf[:@var{stream_specifier}] (@emph{output,per-stream})
584 When doing stream copy, copy also non-key frames found at the
587 @item -hwaccel[:@var{stream_specifier}] @var{hwaccel} (@emph{input,per-stream})
588 Use hardware acceleration to decode the matching stream(s). The allowed values
589 of @var{hwaccel} are:
592 Do not use any hardware acceleration (the default).
595 Automatically select the hardware acceleration method.
598 Use Apple VDA hardware acceleration.
601 Use VDPAU (Video Decode and Presentation API for Unix) hardware acceleration.
604 Use DXVA2 (DirectX Video Acceleration) hardware acceleration.
607 Use the Intel QuickSync Video acceleration for video transcoding.
609 Unlike most other values, this option does not enable accelerated decoding (that
610 is used automatically whenever a qsv decoder is selected), but accelerated
611 transcoding, without copying the frames into the system memory.
613 For it to work, both the decoder and the encoder must support QSV acceleration
614 and no filters must be used.
617 This option has no effect if the selected hwaccel is not available or not
618 supported by the chosen decoder.
620 Note that most acceleration methods are intended for playback and will not be
621 faster than software decoding on modern CPUs. Additionally, @command{avconv}
622 will usually need to copy the decoded frames from the GPU memory into the system
623 memory, resulting in further performance loss. This option is thus mainly
626 @item -hwaccel_device[:@var{stream_specifier}] @var{hwaccel_device} (@emph{input,per-stream})
627 Select a device to use for hardware acceleration.
629 This option only makes sense when the @option{-hwaccel} option is also
630 specified. Its exact meaning depends on the specific hardware acceleration
635 For VDPAU, this option specifies the X11 display/screen to use. If this option
636 is not specified, the value of the @var{DISPLAY} environment variable is used
639 For DXVA2, this option should contain the number of the display adapter to use.
640 If this option is not specified, the default adapter is used.
643 For QSV, this option corresponds to the valus of MFX_IMPL_* . Allowed values
658 List all hardware acceleration methods supported in this build of avconv.
662 @section Audio Options
665 @item -aframes @var{number} (@emph{output})
666 Set the number of audio frames to record. This is an alias for @code{-frames:a}.
667 @item -ar[:@var{stream_specifier}] @var{freq} (@emph{input/output,per-stream})
668 Set the audio sampling frequency. For output streams it is set by
669 default to the frequency of the corresponding input stream. For input
670 streams this option only makes sense for audio grabbing devices and raw
671 demuxers and is mapped to the corresponding demuxer options.
672 @item -aq @var{q} (@emph{output})
673 Set the audio quality (codec-specific, VBR). This is an alias for -q:a.
674 @item -ac[:@var{stream_specifier}] @var{channels} (@emph{input/output,per-stream})
675 Set the number of audio channels. For output streams it is set by
676 default to the number of input audio channels. For input streams
677 this option only makes sense for audio grabbing devices and raw demuxers
678 and is mapped to the corresponding demuxer options.
679 @item -an (@emph{output})
680 Disable audio recording.
681 @item -acodec @var{codec} (@emph{input/output})
682 Set the audio codec. This is an alias for @code{-codec:a}.
683 @item -sample_fmt[:@var{stream_specifier}] @var{sample_fmt} (@emph{output,per-stream})
684 Set the audio sample format. Use @code{-sample_fmts} to get a list
685 of supported sample formats.
686 @item -af @var{filter_graph} (@emph{output})
687 @var{filter_graph} is a description of the filter graph to apply to
689 Use the option "-filters" to show all the available filters (including
690 also sources and sinks). This is an alias for @code{-filter:a}.
693 @section Advanced Audio options:
696 @item -atag @var{fourcc/tag} (@emph{output})
697 Force audio tag/fourcc. This is an alias for @code{-tag:a}.
700 @section Subtitle options:
703 @item -scodec @var{codec} (@emph{input/output})
704 Set the subtitle codec. This is an alias for @code{-codec:s}.
705 @item -sn (@emph{output})
706 Disable subtitle recording.
709 @section Advanced options
712 @item -map [-]@var{input_file_id}[:@var{stream_specifier}][,@var{sync_file_id}[:@var{stream_specifier}]] | @var{[linklabel]} (@emph{output})
714 Designate one or more input streams as a source for the output file. Each input
715 stream is identified by the input file index @var{input_file_id} and
716 the input stream index @var{input_stream_id} within the input
717 file. Both indices start at 0. If specified,
718 @var{sync_file_id}:@var{stream_specifier} sets which input stream
719 is used as a presentation sync reference.
721 The first @code{-map} option on the command line specifies the
722 source for output stream 0, the second @code{-map} option specifies
723 the source for output stream 1, etc.
725 A @code{-} character before the stream identifier creates a "negative" mapping.
726 It disables matching streams from already created mappings.
728 An alternative @var{[linklabel]} form will map outputs from complex filter
729 graphs (see the @option{-filter_complex} option) to the output file.
730 @var{linklabel} must correspond to a defined output link label in the graph.
732 For example, to map ALL streams from the first input file to output
734 avconv -i INPUT -map 0 output
737 For example, if you have two audio streams in the first input file,
738 these streams are identified by "0:0" and "0:1". You can use
739 @code{-map} to select which streams to place in an output file. For
742 avconv -i INPUT -map 0:1 out.wav
744 will map the input stream in @file{INPUT} identified by "0:1" to
745 the (single) output stream in @file{out.wav}.
747 For example, to select the stream with index 2 from input file
748 @file{a.mov} (specified by the identifier "0:2"), and stream with
749 index 6 from input @file{b.mov} (specified by the identifier "1:6"),
750 and copy them to the output file @file{out.mov}:
752 avconv -i a.mov -i b.mov -c copy -map 0:2 -map 1:6 out.mov
755 To select all video and the third audio stream from an input file:
757 avconv -i INPUT -map 0:v -map 0:a:2 OUTPUT
760 To map all the streams except the second audio, use negative mappings
762 avconv -i INPUT -map 0 -map -0:a:1 OUTPUT
765 To pick the English audio stream:
767 avconv -i INPUT -map 0:m:language:eng OUTPUT
770 Note that using this option disables the default mappings for this output file.
772 @item -map_metadata[:@var{metadata_spec_out}] @var{infile}[:@var{metadata_spec_in}] (@emph{output,per-metadata})
773 Set metadata information of the next output file from @var{infile}. Note that
774 those are file indices (zero-based), not filenames.
775 Optional @var{metadata_spec_in/out} parameters specify, which metadata to copy.
776 A metadata specifier can have the following forms:
779 global metadata, i.e. metadata that applies to the whole file
781 @item @var{s}[:@var{stream_spec}]
782 per-stream metadata. @var{stream_spec} is a stream specifier as described
783 in the @ref{Stream specifiers} chapter. In an input metadata specifier, the first
784 matching stream is copied from. In an output metadata specifier, all matching
785 streams are copied to.
787 @item @var{c}:@var{chapter_index}
788 per-chapter metadata. @var{chapter_index} is the zero-based chapter index.
790 @item @var{p}:@var{program_index}
791 per-program metadata. @var{program_index} is the zero-based program index.
793 If metadata specifier is omitted, it defaults to global.
795 By default, global metadata is copied from the first input file,
796 per-stream and per-chapter metadata is copied along with streams/chapters. These
797 default mappings are disabled by creating any mapping of the relevant type. A negative
798 file index can be used to create a dummy mapping that just disables automatic copying.
800 For example to copy metadata from the first stream of the input file to global metadata
803 avconv -i in.ogg -map_metadata 0:s:0 out.mp3
806 To do the reverse, i.e. copy global metadata to all audio streams:
808 avconv -i in.mkv -map_metadata:s:a 0:g out.mkv
810 Note that simple @code{0} would work as well in this example, since global
811 metadata is assumed by default.
813 @item -map_chapters @var{input_file_index} (@emph{output})
814 Copy chapters from input file with index @var{input_file_index} to the next
815 output file. If no chapter mapping is specified, then chapters are copied from
816 the first input file with at least one chapter. Use a negative file index to
817 disable any chapter copying.
819 Print specific debug info.
820 @item -benchmark (@emph{global})
821 Show benchmarking information at the end of an encode.
822 Shows CPU time used and maximum memory consumption.
823 Maximum memory consumption is not supported on all systems,
824 it will usually display as 0 if not supported.
825 @item -timelimit @var{duration} (@emph{global})
826 Exit after avconv has been running for @var{duration} seconds.
827 @item -dump (@emph{global})
828 Dump each input packet to stderr.
829 @item -hex (@emph{global})
830 When dumping packets, also dump the payload.
831 @item -re (@emph{input})
832 Read input at native frame rate. Mainly used to simulate a grab device
833 or live input stream (e.g. when reading from a file). Should not be used
834 with actual grab devices or live input streams (where it can cause packet
836 @item -vsync @var{parameter}
841 Each frame is passed with its timestamp from the demuxer to the muxer.
843 Frames will be duplicated and dropped to achieve exactly the requested
846 Frames are passed through with their timestamp or dropped so as to
847 prevent 2 frames from having the same timestamp.
849 Chooses between 1 and 2 depending on muxer capabilities. This is the
853 With -map you can select from which stream the timestamps should be
854 taken. You can leave either video or audio unchanged and sync the
855 remaining stream(s) to the unchanged one.
857 @item -async @var{samples_per_second}
858 Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
859 the parameter is the maximum samples per second by which the audio is changed.
860 -async 1 is a special case where only the start of the audio stream is corrected
861 without any later correction.
862 This option has been deprecated. Use the @code{asyncts} audio filter instead.
864 Copy timestamps from input to output.
866 Copy input stream time base from input to output when stream copying.
867 @item -shortest (@emph{output})
868 Finish encoding when the shortest input stream ends.
869 @item -dts_delta_threshold
870 Timestamp discontinuity delta threshold.
871 @item -muxdelay @var{seconds} (@emph{input})
872 Set the maximum demux-decode delay.
873 @item -muxpreload @var{seconds} (@emph{input})
874 Set the initial demux-decode delay.
875 @item -streamid @var{output-stream-index}:@var{new-value} (@emph{output})
876 Assign a new stream-id value to an output stream. This option should be
877 specified prior to the output filename to which it applies.
878 For the situation where multiple output files exist, a streamid
879 may be reassigned to a different value.
881 For example, to set the stream 0 PID to 33 and the stream 1 PID to 36 for
882 an output mpegts file:
884 avconv -i infile -streamid 0:33 -streamid 1:36 out.ts
887 @item -bsf[:@var{stream_specifier}] @var{bitstream_filters} (@emph{output,per-stream})
888 Set bitstream filters for matching streams. @var{bistream_filters} is
889 a comma-separated list of bitstream filters. Use the @code{-bsfs} option
890 to get the list of bitstream filters.
892 avconv -i h264.mp4 -c:v copy -bsf:v h264_mp4toannexb -an out.h264
895 avconv -i file.mov -an -vn -bsf:s mov2textsub -c:s copy -f rawvideo sub.txt
898 @item -tag[:@var{stream_specifier}] @var{codec_tag} (@emph{input/output,per-stream})
899 Force a tag/fourcc for matching streams.
901 @item -filter_complex @var{filtergraph} (@emph{global})
902 Define a complex filter graph, i.e. one with arbitrary number of inputs and/or
903 outputs. For simple graphs -- those with one input and one output of the same
904 type -- see the @option{-filter} options. @var{filtergraph} is a description of
905 the filter graph, as described in @ref{Filtergraph syntax}.
907 Input link labels must refer to input streams using the
908 @code{[file_index:stream_specifier]} syntax (i.e. the same as @option{-map}
909 uses). If @var{stream_specifier} matches multiple streams, the first one will be
910 used. An unlabeled input will be connected to the first unused input stream of
913 Output link labels are referred to with @option{-map}. Unlabeled outputs are
914 added to the first output file.
916 Note that with this option it is possible to use only lavfi sources without
919 For example, to overlay an image over video
921 avconv -i video.mkv -i image.png -filter_complex '[0:v][1:v]overlay[out]' -map
924 Here @code{[0:v]} refers to the first video stream in the first input file,
925 which is linked to the first (main) input of the overlay filter. Similarly the
926 first video stream in the second input is linked to the second (overlay) input
929 Assuming there is only one video stream in each input file, we can omit input
930 labels, so the above is equivalent to
932 avconv -i video.mkv -i image.png -filter_complex 'overlay[out]' -map
936 Furthermore we can omit the output label and the single output from the filter
937 graph will be added to the output file automatically, so we can simply write
939 avconv -i video.mkv -i image.png -filter_complex 'overlay' out.mkv
942 To generate 5 seconds of pure red video using lavfi @code{color} source:
944 avconv -filter_complex 'color=red' -t 5 out.mkv
947 @item -filter_complex_script @var{filename} (@emph{global})
948 This option is similar to @option{-filter_complex}, the only difference is that
949 its argument is the name of the file from which a complex filtergraph
950 description is to be read.
952 @item -accurate_seek (@emph{input})
953 This option enables or disables accurate seeking in input files with the
954 @option{-ss} option. It is enabled by default, so seeking is accurate when
955 transcoding. Use @option{-noaccurate_seek} to disable it, which may be useful
956 e.g. when copying some streams and transcoding the others.
966 For streaming at very low bitrate application, use a low frame rate
967 and a small GOP size. This is especially true for RealVideo where
968 the Linux player does not seem to be very fast, so it can miss
969 frames. An example is:
972 avconv -g 3 -r 3 -t 10 -b 50k -s qcif -f rv10 /tmp/b.rm
976 The parameter 'q' which is displayed while encoding is the current
977 quantizer. The value 1 indicates that a very good quality could
978 be achieved. The value 31 indicates the worst quality. If q=31 appears
979 too often, it means that the encoder cannot compress enough to meet
980 your bitrate. You must either increase the bitrate, decrease the
981 frame rate or decrease the frame size.
984 If your computer is not fast enough, you can speed up the
985 compression at the expense of the compression ratio. You can use
986 '-me zero' to speed up motion estimation, and '-g 0' to disable
987 motion estimation completely (you have only I-frames, which means it
988 is about as good as JPEG compression).
991 To have very low audio bitrates, reduce the sampling frequency
992 (down to 22050 Hz for MPEG audio, 22050 or 11025 for AC-3).
995 To have a constant quality (but a variable bitrate), use the option
996 '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
1003 @c man begin EXAMPLES
1005 @section Preset files
1007 A preset file contains a sequence of @var{option=value} pairs, one for
1008 each line, specifying a sequence of options which can be specified also on
1009 the command line. Lines starting with the hash ('#') character are ignored and
1010 are used to provide comments. Empty lines are also ignored. Check the
1011 @file{presets} directory in the Libav source tree for examples.
1013 Preset files are specified with the @code{pre} option, this option takes a
1014 preset name as input. Avconv searches for a file named @var{preset_name}.avpreset in
1015 the directories @file{$AVCONV_DATADIR} (if set), and @file{$HOME/.avconv}, and in
1016 the data directory defined at configuration time (usually @file{$PREFIX/share/avconv})
1017 in that order. For example, if the argument is @code{libx264-max}, it will
1018 search for the file @file{libx264-max.avpreset}.
1020 @section Video and Audio grabbing
1022 If you specify the input format and device then avconv can grab video
1026 avconv -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
1029 Note that you must activate the right video source and channel before
1030 launching avconv with any TV viewer such as
1031 @uref{http://linux.bytesex.org/xawtv/, xawtv} by Gerd Knorr. You also
1032 have to set the audio recording levels correctly with a
1035 @section X11 grabbing
1037 Grab the X11 display with avconv via
1040 avconv -f x11grab -s cif -r 25 -i :0.0 /tmp/out.mpg
1043 0.0 is display.screen number of your X11 server, same as
1044 the DISPLAY environment variable.
1047 avconv -f x11grab -s cif -r 25 -i :0.0+10,20 /tmp/out.mpg
1050 0.0 is display.screen number of your X11 server, same as the DISPLAY environment
1051 variable. 10 is the x-offset and 20 the y-offset for the grabbing.
1053 @section Video and Audio file format conversion
1055 Any supported file format and protocol can serve as input to avconv:
1060 You can use YUV files as input:
1063 avconv -i /tmp/test%d.Y /tmp/out.mpg
1066 It will use the files:
1068 /tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
1069 /tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
1072 The Y files use twice the resolution of the U and V files. They are
1073 raw files, without header. They can be generated by all decent video
1074 decoders. You must specify the size of the image with the @option{-s} option
1075 if avconv cannot guess it.
1078 You can input from a raw YUV420P file:
1081 avconv -i /tmp/test.yuv /tmp/out.avi
1084 test.yuv is a file containing raw YUV planar data. Each frame is composed
1085 of the Y plane followed by the U and V planes at half vertical and
1086 horizontal resolution.
1089 You can output to a raw YUV420P file:
1092 avconv -i mydivx.avi hugefile.yuv
1096 You can set several input files and output files:
1099 avconv -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
1102 Converts the audio file a.wav and the raw YUV video file a.yuv
1106 You can also do audio and video conversions at the same time:
1109 avconv -i /tmp/a.wav -ar 22050 /tmp/a.mp2
1112 Converts a.wav to MPEG audio at 22050 Hz sample rate.
1115 You can encode to several formats at the same time and define a
1116 mapping from input stream to output streams:
1119 avconv -i /tmp/a.wav -map 0:a -b 64k /tmp/a.mp2 -map 0:a -b 128k /tmp/b.mp2
1122 Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
1123 file:index' specifies which input stream is used for each output
1124 stream, in the order of the definition of output streams.
1127 You can transcode decrypted VOBs:
1130 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
1133 This is a typical DVD ripping example; the input is a VOB file, the
1134 output an AVI file with MPEG-4 video and MP3 audio. Note that in this
1135 command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
1136 GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
1137 input video. Furthermore, the audio stream is MP3-encoded so you need
1138 to enable LAME support by passing @code{--enable-libmp3lame} to configure.
1139 The mapping is particularly useful for DVD transcoding
1140 to get the desired audio language.
1142 NOTE: To see the supported input formats, use @code{avconv -formats}.
1145 You can extract images from a video, or create a video from many images:
1147 For extracting images from a video:
1149 avconv -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg
1152 This will extract one video frame per second from the video and will
1153 output them in files named @file{foo-001.jpeg}, @file{foo-002.jpeg},
1154 etc. Images will be rescaled to fit the new WxH values.
1156 If you want to extract just a limited number of frames, you can use the
1157 above command in combination with the -vframes or -t option, or in
1158 combination with -ss to start extracting from a certain point in time.
1160 For creating a video from many images:
1162 avconv -f image2 -i foo-%03d.jpeg -r 12 -s WxH foo.avi
1165 The syntax @code{foo-%03d.jpeg} specifies to use a decimal number
1166 composed of three digits padded with zeroes to express the sequence
1167 number. It is the same syntax supported by the C printf function, but
1168 only formats accepting a normal integer are suitable.
1171 You can put many streams of the same type in the output:
1174 avconv -i test1.avi -i test2.avi -map 1:1 -map 1:0 -map 0:1 -map 0:0 -c copy -y test12.nut
1177 The resulting output file @file{test12.nut} will contain the first four streams
1178 from the input files in reverse order.
1181 To force CBR video output:
1183 avconv -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v
1187 The four options lmin, lmax, mblmin and mblmax use 'lambda' units,
1188 but you may use the QP2LAMBDA constant to easily convert from 'q' units:
1190 avconv -i src.ext -lmax 21*QP2LAMBDA dst.ext
1197 @include decoders.texi
1198 @include encoders.texi
1199 @include demuxers.texi
1200 @include muxers.texi
1201 @include indevs.texi
1202 @include outdevs.texi
1203 @include protocols.texi
1204 @include bitstream_filters.texi
1205 @include filters.texi
1206 @include metadata.texi
1211 @settitle avconv video converter
1213 @c man begin SEEALSO
1214 avplay(1), avprobe(1) and the Libav HTML documentation
1217 @c man begin AUTHORS
1218 The Libav developers