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 Stream selection
83 @c man begin STREAM SELECTION
85 By default avconv tries to pick the "best" stream of each type present in input
86 files and add them to each output file. For video, this means the highest
87 resolution, for audio the highest channel count. For subtitle it's simply the
88 first subtitle stream.
90 You can disable some of those defaults by using @code{-vn/-an/-sn} options. For
91 full manual control, use the @code{-map} option, which disables the defaults just
94 @c man end STREAM SELECTION
99 @include avtools-common-opts.texi
101 @section Main options
105 @item -f @var{fmt} (@emph{input/output})
106 Force input or output file format. The format is normally autodetected for input
107 files and guessed from file extension for output files, so this option is not
108 needed in most cases.
110 @item -i @var{filename} (@emph{input})
113 @item -y (@emph{global})
114 Overwrite output files without asking.
116 @item -c[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
117 @itemx -codec[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream})
118 Select an encoder (when used before an output file) or a decoder (when used
119 before an input file) for one or more streams. @var{codec} is the name of a
120 decoder/encoder or a special value @code{copy} (output only) to indicate that
121 the stream is not to be reencoded.
125 avconv -i INPUT -map 0 -c:v libx264 -c:a copy OUTPUT
127 encodes all video streams with libx264 and copies all audio streams.
129 For each stream, the last matching @code{c} option is applied, so
131 avconv -i INPUT -map 0 -c copy -c:v:1 libx264 -c:a:137 libvorbis OUTPUT
133 will copy all the streams except the second video, which will be encoded with
134 libx264, and the 138th audio, which will be encoded with libvorbis.
136 @item -t @var{duration} (@emph{output})
137 Stop writing the output after its duration reaches @var{duration}.
138 @var{duration} may be a number in seconds, or in @code{hh:mm:ss[.xxx]} form.
140 @item -fs @var{limit_size} (@emph{output})
141 Set the file size limit.
143 @item -ss @var{position} (@emph{input/output})
144 When used as an input option (before @code{-i}), seeks in this input file to
145 @var{position}. When used as an output option (before an output filename),
146 decodes but discards input until the timestamps reach @var{position}. This is
147 slower, but more accurate.
149 @var{position} may be either in seconds or in @code{hh:mm:ss[.xxx]} form.
151 @item -itsoffset @var{offset} (@emph{input})
152 Set the input time offset in seconds.
153 @code{[-]hh:mm:ss[.xxx]} syntax is also supported.
154 The offset is added to the timestamps of the input files.
155 Specifying a positive offset means that the corresponding
156 streams are delayed by @var{offset} seconds.
158 @item -metadata[:metadata_specifier] @var{key}=@var{value} (@emph{output,per-metadata})
159 Set a metadata key/value pair.
161 An optional @var{metadata_specifier} may be given to set metadata
162 on streams or chapters. See @code{-map_metadata} documentation for
165 This option overrides metadata set with @code{-map_metadata}. It is
166 also possible to delete metadata by using an empty value.
168 For example, for setting the title in the output file:
170 avconv -i in.avi -metadata title="my title" out.flv
173 To set the language of the first audio stream:
175 avconv -i INPUT -metadata:s:a:0 language=eng OUTPUT
178 @item -target @var{type} (@emph{output})
179 Specify target file type (@code{vcd}, @code{svcd}, @code{dvd}, @code{dv},
180 @code{dv50}). @var{type} may be prefixed with @code{pal-}, @code{ntsc-} or
181 @code{film-} to use the corresponding standard. All the format options
182 (bitrate, codecs, buffer sizes) are then set automatically. You can just type:
185 avconv -i myfile.avi -target vcd /tmp/vcd.mpg
188 Nevertheless you can specify additional options as long as you know
189 they do not conflict with the standard, as in:
192 avconv -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg
195 @item -dframes @var{number} (@emph{output})
196 Set the number of data frames to record. This is an alias for @code{-frames:d}.
198 @item -frames[:@var{stream_specifier}] @var{framecount} (@emph{output,per-stream})
199 Stop writing to the stream after @var{framecount} frames.
201 @item -q[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
202 @itemx -qscale[:@var{stream_specifier}] @var{q} (@emph{output,per-stream})
203 Use fixed quality scale (VBR). The meaning of @var{q} is
206 @item -filter[:@var{stream_specifier}] @var{filter_graph} (@emph{output,per-stream})
207 @var{filter_graph} is a description of the filter graph to apply to
208 the stream. Use @code{-filters} to show all the available filters
209 (including also sources and sinks).
210 @item -pre[:@var{stream_specifier}] @var{preset_name} (@emph{output,per-stream})
211 Specify the preset for matching stream(s).
213 @item -stats (@emph{global})
214 Print encoding progress/statistics. On by default.
216 @item -attach @var{filename} (@emph{output})
217 Add an attachment to the output file. This is supported by a few formats
218 like Matroska for e.g. fonts used in rendering subtitles. Attachments
219 are implemented as a specific type of stream, so this option will add
220 a new stream to the file. It is then possible to use per-stream options
221 on this stream in the usual way. Attachment streams created with this
222 option will be created after all the other streams (i.e. those created
223 with @code{-map} or automatic mappings).
225 Note that for Matroska you also have to set the mimetype metadata tag:
227 avconv -i INPUT -attach DejaVuSans.ttf -metadata:s:2 mimetype=application/x-truetype-font out.mkv
229 (assuming that the attachment stream will be third in the output file).
231 @item -dump_attachment[:@var{stream_specifier}] @var{filename} (@emph{input,per-stream})
232 Extract the matching attachment stream into a file named @var{filename}. If
233 @var{filename} is empty, then the value of the @code{filename} metadata tag
236 E.g. to extract the first attachment to a file named 'out.ttf':
238 avconv -dump_attachment:t:0 out.ttf INPUT
240 To extract all attachments to files determined by the @code{filename} tag:
242 avconv -dump_attachment:t "" INPUT
245 Technical note -- attachments are implemented as codec extradata, so this
246 option can actually be used to extract extradata from any stream, not just
251 @section Video Options
254 @item -vframes @var{number} (@emph{output})
255 Set the number of video frames to record. This is an alias for @code{-frames:v}.
256 @item -r[:@var{stream_specifier}] @var{fps} (@emph{input/output,per-stream})
257 Set frame rate (Hz value, fraction or abbreviation), (default = 25). For output
258 streams implies @code{-vsync cfr}.
259 @item -s[:@var{stream_specifier}] @var{size} (@emph{input/output,per-stream})
260 Set frame size. The format is @samp{wxh} (default - same as source).
261 The following abbreviations are recognized:
323 @item -aspect[:@var{stream_specifier}] @var{aspect} (@emph{output,per-stream})
324 Set the video display aspect ratio specified by @var{aspect}.
326 @var{aspect} can be a floating point number string, or a string of the
327 form @var{num}:@var{den}, where @var{num} and @var{den} are the
328 numerator and denominator of the aspect ratio. For example "4:3",
329 "16:9", "1.3333", and "1.7777" are valid argument values.
331 @item -vn (@emph{output})
332 Disable video recording.
333 @item -bt @var{tolerance}
334 Set video bitrate tolerance (in bits, default 4000k).
335 Has a minimum value of: (target_bitrate/target_framerate).
336 In 1-pass mode, bitrate tolerance specifies how far ratecontrol is
337 willing to deviate from the target average bitrate value. This is
338 not related to min/max bitrate. Lowering tolerance too much has
339 an adverse effect on quality.
340 @item -maxrate @var{bitrate}
341 Set max video bitrate (in bit/s).
342 Requires -bufsize to be set.
343 @item -minrate @var{bitrate}
344 Set min video bitrate (in bit/s).
345 Most useful in setting up a CBR encode:
347 avconv -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v
349 It is of little use elsewise.
350 @item -bufsize @var{size}
351 Set video buffer verifier buffer size (in bits).
352 @item -vcodec @var{codec} (@emph{output})
353 Set the video codec. This is an alias for @code{-codec:v}.
355 Use same quantizer as source (implies VBR).
357 Note that this is NOT SAME QUALITY. Do not use this option unless you know you
361 Select the pass number (1 or 2). It is used to do two-pass
362 video encoding. The statistics of the video are recorded in the first
363 pass into a log file (see also the option -passlogfile),
364 and in the second pass that log file is used to generate the video
365 at the exact requested bitrate.
366 On pass 1, you may just deactivate audio and set output to null,
367 examples for Windows and Unix:
369 avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y NUL
370 avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null
373 @item -passlogfile @var{prefix} (@emph{global})
374 Set two-pass log file name prefix to @var{prefix}, the default file name
375 prefix is ``av2pass''. The complete file name will be
376 @file{PREFIX-N.log}, where N is a number specific to the output
379 @item -vf @var{filter_graph} (@emph{output})
380 @var{filter_graph} is a description of the filter graph to apply to
382 Use the option "-filters" to show all the available filters (including
383 also sources and sinks). This is an alias for @code{-filter:v}.
387 @section Advanced Video Options
390 @item -pix_fmt[:@var{stream_specifier}] @var{format} (@emph{input/output,per-stream})
391 Set pixel format. Use @code{-pix_fmts} to show all the supported
393 @item -sws_flags @var{flags} (@emph{input/output})
395 @item -g @var{gop_size}
396 Set the group of pictures size.
400 minimum video quantizer scale (VBR)
402 maximum video quantizer scale (VBR)
404 maximum difference between the quantizer scales (VBR)
405 @item -qblur @var{blur}
406 video quantizer scale blur (VBR) (range 0.0 - 1.0)
407 @item -qcomp @var{compression}
408 video quantizer scale compression (VBR) (default 0.5).
409 Constant of ratecontrol equation. Recommended range for default rc_eq: 0.0-1.0
411 @item -lmin @var{lambda}
412 minimum video lagrange factor (VBR)
413 @item -lmax @var{lambda}
414 max video lagrange factor (VBR)
415 @item -mblmin @var{lambda}
416 minimum macroblock quantizer scale (VBR)
417 @item -mblmax @var{lambda}
418 maximum macroblock quantizer scale (VBR)
420 These four options (lmin, lmax, mblmin, mblmax) use 'lambda' units,
421 but you may use the QP2LAMBDA constant to easily convert from 'q' units:
423 avconv -i src.ext -lmax 21*QP2LAMBDA dst.ext
426 @item -rc_init_cplx @var{complexity}
427 initial complexity for single pass encoding
428 @item -b_qfactor @var{factor}
429 qp factor between P- and B-frames
430 @item -i_qfactor @var{factor}
431 qp factor between P- and I-frames
432 @item -b_qoffset @var{offset}
433 qp offset between P- and B-frames
434 @item -i_qoffset @var{offset}
435 qp offset between P- and I-frames
436 @item -rc_eq @var{equation}
437 Set rate control equation (see section "Expression Evaluation")
438 (default = @code{tex^qComp}).
440 When computing the rate control equation expression, besides the
441 standard functions defined in the section "Expression Evaluation", the
442 following functions are available:
448 and the following constants are available:
470 @item -rc_override[:@var{stream_specifier}] @var{override} (@emph{output,per-stream})
471 rate control override for specific intervals
472 @item -me_method @var{method}
473 Set motion estimation method to @var{method}.
474 Available methods are (from lowest to best quality):
477 Try just the (0, 0) vector.
486 exhaustive search (slow and marginally better than epzs)
490 Set error resilience to @var{n}.
493 FF_ER_CAREFUL (default)
499 FF_ER_VERY_AGGRESSIVE
502 @item -ec @var{bit_mask}
503 Set error concealment to @var{bit_mask}. @var{bit_mask} is a bit mask of
504 the following values:
507 FF_EC_GUESS_MVS (default = enabled)
509 FF_EC_DEBLOCK (default = enabled)
512 @item -bf @var{frames}
513 Use 'frames' B-frames (supported for MPEG-1, MPEG-2 and MPEG-4).
514 @item -mbd @var{mode}
518 FF_MB_DECISION_SIMPLE: Use mb_cmp (cannot change it yet in avconv).
520 FF_MB_DECISION_BITS: Choose the one which needs the fewest bits.
522 FF_MB_DECISION_RD: rate distortion
525 @item -bug @var{param}
526 Work around encoder bugs that are not auto-detected.
527 @item -strict @var{strictness}
528 How strictly to follow the standards.
531 Deinterlace pictures.
532 This option is deprecated since the deinterlacing is very low quality.
533 Use the yadif filter with @code{-filter:v yadif}.
535 Dump video coding statistics to @file{vstats_HHMMSS.log}.
536 @item -vstats_file @var{file}
537 Dump video coding statistics to @var{file}.
538 @item -top[:@var{stream_specifier}] @var{n} (@emph{output,per-stream})
539 top=1/bottom=0/auto=-1 field first
540 @item -dc @var{precision}
542 @item -vtag @var{fourcc/tag} (@emph{output})
543 Force video tag/fourcc. This is an alias for @code{-tag:v}.
544 @item -qphist (@emph{global})
546 @item -force_key_frames[:@var{stream_specifier}] @var{time}[,@var{time}...] (@emph{output,per-stream})
547 Force key frames at the specified timestamps, more precisely at the first
548 frames after each specified time.
549 This option can be useful to ensure that a seek point is present at a
550 chapter mark or any other designated place in the output file.
551 The timestamps must be specified in ascending order.
553 @item -copyinkf[:@var{stream_specifier}] (@emph{output,per-stream})
554 When doing stream copy, copy also non-key frames found at the
558 @section Audio Options
561 @item -aframes @var{number} (@emph{output})
562 Set the number of audio frames to record. This is an alias for @code{-frames:a}.
563 @item -ar[:@var{stream_specifier}] @var{freq} (@emph{input/output,per-stream})
564 Set the audio sampling frequency. For output streams it is set by
565 default to the frequency of the corresponding input stream. For input
566 streams this option only makes sense for audio grabbing devices and raw
567 demuxers and is mapped to the corresponding demuxer options.
568 @item -aq @var{q} (@emph{output})
569 Set the audio quality (codec-specific, VBR). This is an alias for -q:a.
570 @item -ac[:@var{stream_specifier}] @var{channels} (@emph{input/output,per-stream})
571 Set the number of audio channels. For output streams it is set by
572 default to the number of input audio channels. For input streams
573 this option only makes sense for audio grabbing devices and raw demuxers
574 and is mapped to the corresponding demuxer options.
575 @item -an (@emph{output})
576 Disable audio recording.
577 @item -acodec @var{codec} (@emph{input/output})
578 Set the audio codec. This is an alias for @code{-codec:a}.
579 @item -sample_fmt[:@var{stream_specifier}] @var{sample_fmt} (@emph{output,per-stream})
580 Set the audio sample format. Use @code{-sample_fmts} to get a list
581 of supported sample formats.
584 @section Advanced Audio options:
587 @item -atag @var{fourcc/tag} (@emph{output})
588 Force audio tag/fourcc. This is an alias for @code{-tag:a}.
589 @item -audio_service_type @var{type}
590 Set the type of service that the audio stream contains.
593 Main Audio Service (default)
613 @section Subtitle options:
616 @item -scodec @var{codec} (@emph{input/output})
617 Set the subtitle codec. This is an alias for @code{-codec:s}.
618 @item -sn (@emph{output})
619 Disable subtitle recording.
622 @section Audio/Video grab options
625 @item -isync (@emph{global})
626 Synchronize read on input.
629 @section Advanced options
632 @item -map [-]@var{input_file_id}[:@var{stream_specifier}][,@var{sync_file_id}[:@var{stream_specifier}]] (@emph{output})
634 Designate one or more input streams as a source for the output file. Each input
635 stream is identified by the input file index @var{input_file_id} and
636 the input stream index @var{input_stream_id} within the input
637 file. Both indices start at 0. If specified,
638 @var{sync_file_id}:@var{stream_specifier} sets which input stream
639 is used as a presentation sync reference.
641 The first @code{-map} option on the command line specifies the
642 source for output stream 0, the second @code{-map} option specifies
643 the source for output stream 1, etc.
645 A @code{-} character before the stream identifier creates a "negative" mapping.
646 It disables matching streams from already created mappings.
648 For example, to map ALL streams from the first input file to output
650 avconv -i INPUT -map 0 output
653 For example, if you have two audio streams in the first input file,
654 these streams are identified by "0:0" and "0:1". You can use
655 @code{-map} to select which streams to place in an output file. For
658 avconv -i INPUT -map 0:1 out.wav
660 will map the input stream in @file{INPUT} identified by "0:1" to
661 the (single) output stream in @file{out.wav}.
663 For example, to select the stream with index 2 from input file
664 @file{a.mov} (specified by the identifier "0:2"), and stream with
665 index 6 from input @file{b.mov} (specified by the identifier "1:6"),
666 and copy them to the output file @file{out.mov}:
668 avconv -i a.mov -i b.mov -c copy -map 0:2 -map 1:6 out.mov
671 To select all video and the third audio stream from an input file:
673 avconv -i INPUT -map 0:v -map 0:a:2 OUTPUT
676 To map all the streams except the second audio, use negative mappings
678 avconv -i INPUT -map 0 -map -0:a:1 OUTPUT
681 Note that using this option disables the default mappings for this output file.
683 @item -map_metadata[:@var{metadata_spec_out}] @var{infile}[:@var{metadata_spec_in}] (@emph{output,per-metadata})
684 Set metadata information of the next output file from @var{infile}. Note that
685 those are file indices (zero-based), not filenames.
686 Optional @var{metadata_spec_in/out} parameters specify, which metadata to copy.
687 A metadata specifier can have the following forms:
690 global metadata, i.e. metadata that applies to the whole file
692 @item @var{s}[:@var{stream_spec}]
693 per-stream metadata. @var{stream_spec} is a stream specifier as described
694 in the @ref{Stream specifiers} chapter. In an input metadata specifier, the first
695 matching stream is copied from. In an output metadata specifier, all matching
696 streams are copied to.
698 @item @var{c}:@var{chapter_index}
699 per-chapter metadata. @var{chapter_index} is the zero-based chapter index.
701 @item @var{p}:@var{program_index}
702 per-program metadata. @var{program_index} is the zero-based program index.
704 If metadata specifier is omitted, it defaults to global.
706 By default, global metadata is copied from the first input file,
707 per-stream and per-chapter metadata is copied along with streams/chapters. These
708 default mappings are disabled by creating any mapping of the relevant type. A negative
709 file index can be used to create a dummy mapping that just disables automatic copying.
711 For example to copy metadata from the first stream of the input file to global metadata
714 avconv -i in.ogg -map_metadata 0:s:0 out.mp3
717 To do the reverse, i.e. copy global metadata to all audio streams:
719 avconv -i in.mkv -map_metadata:s:a 0:g out.mkv
721 Note that simple @code{0} would work as well in this example, since global
722 metadata is assumed by default.
724 @item -map_chapters @var{input_file_index} (@emph{output})
725 Copy chapters from input file with index @var{input_file_index} to the next
726 output file. If no chapter mapping is specified, then chapters are copied from
727 the first input file with at least one chapter. Use a negative file index to
728 disable any chapter copying.
730 Print specific debug info.
731 @item -benchmark (@emph{global})
732 Show benchmarking information at the end of an encode.
733 Shows CPU time used and maximum memory consumption.
734 Maximum memory consumption is not supported on all systems,
735 it will usually display as 0 if not supported.
736 @item -timelimit @var{duration} (@emph{global})
737 Exit after avconv has been running for @var{duration} seconds.
738 @item -dump (@emph{global})
739 Dump each input packet to stderr.
740 @item -hex (@emph{global})
741 When dumping packets, also dump the payload.
743 Set RTP payload size in bytes.
744 @item -re (@emph{input})
745 Read input at native frame rate. Mainly used to simulate a grab device.
746 @item -threads @var{count}
748 @item -vsync @var{parameter}
753 Each frame is passed with its timestamp from the demuxer to the muxer.
755 Frames will be duplicated and dropped to achieve exactly the requested
758 Frames are passed through with their timestamp or dropped so as to
759 prevent 2 frames from having the same timestamp.
761 Chooses between 1 and 2 depending on muxer capabilities. This is the
765 With -map you can select from which stream the timestamps should be
766 taken. You can leave either video or audio unchanged and sync the
767 remaining stream(s) to the unchanged one.
769 @item -async @var{samples_per_second}
770 Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps,
771 the parameter is the maximum samples per second by which the audio is changed.
772 -async 1 is a special case where only the start of the audio stream is corrected
773 without any later correction.
775 Copy timestamps from input to output.
777 Copy input stream time base from input to output when stream copying.
779 Finish encoding when the shortest input stream ends.
780 @item -dts_delta_threshold
781 Timestamp discontinuity delta threshold.
782 @item -muxdelay @var{seconds} (@emph{input})
783 Set the maximum demux-decode delay.
784 @item -muxpreload @var{seconds} (@emph{input})
785 Set the initial demux-decode delay.
786 @item -streamid @var{output-stream-index}:@var{new-value} (@emph{output})
787 Assign a new stream-id value to an output stream. This option should be
788 specified prior to the output filename to which it applies.
789 For the situation where multiple output files exist, a streamid
790 may be reassigned to a different value.
792 For example, to set the stream 0 PID to 33 and the stream 1 PID to 36 for
793 an output mpegts file:
795 avconv -i infile -streamid 0:33 -streamid 1:36 out.ts
798 @item -bsf[:@var{stream_specifier}] @var{bitstream_filters} (@emph{output,per-stream})
799 Set bitstream filters for matching streams. @var{bistream_filters} is
800 a comma-separated list of bitstream filters. Use the @code{-bsfs} option
801 to get the list of bitstream filters.
803 avconv -i h264.mp4 -c:v copy -bsf:v h264_mp4toannexb -an out.h264
806 avconv -i file.mov -an -vn -bsf:s mov2textsub -c:s copy -f rawvideo sub.txt
809 @item -tag[:@var{stream_specifier}] @var{codec_tag} (@emph{output,per-stream})
810 Force a tag/fourcc for matching streams.
812 @item -cpuflags mask (@emph{global})
813 Set a mask that's applied to autodetected CPU flags. This option is intended
814 for testing. Do not use it unless you know what you're doing.
823 For streaming at very low bitrate application, use a low frame rate
824 and a small GOP size. This is especially true for RealVideo where
825 the Linux player does not seem to be very fast, so it can miss
826 frames. An example is:
829 avconv -g 3 -r 3 -t 10 -b 50k -s qcif -f rv10 /tmp/b.rm
833 The parameter 'q' which is displayed while encoding is the current
834 quantizer. The value 1 indicates that a very good quality could
835 be achieved. The value 31 indicates the worst quality. If q=31 appears
836 too often, it means that the encoder cannot compress enough to meet
837 your bitrate. You must either increase the bitrate, decrease the
838 frame rate or decrease the frame size.
841 If your computer is not fast enough, you can speed up the
842 compression at the expense of the compression ratio. You can use
843 '-me zero' to speed up motion estimation, and '-intra' to disable
844 motion estimation completely (you have only I-frames, which means it
845 is about as good as JPEG compression).
848 To have very low audio bitrates, reduce the sampling frequency
849 (down to 22050 Hz for MPEG audio, 22050 or 11025 for AC-3).
852 To have a constant quality (but a variable bitrate), use the option
853 '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst
860 @c man begin EXAMPLES
862 @section Preset files
864 A preset file contains a sequence of @var{option=value} pairs, one for
865 each line, specifying a sequence of options which can be specified also on
866 the command line. Lines starting with the hash ('#') character are ignored and
867 are used to provide comments. Empty lines are also ignored. Check the
868 @file{presets} directory in the Libav source tree for examples.
870 Preset files are specified with the @code{pre} option, this option takes a
871 preset name as input. Avconv searches for a file named @var{preset_name}.avpreset in
872 the directories @file{$AVCONV_DATADIR} (if set), and @file{$HOME/.avconv}, and in
873 the data directory defined at configuration time (usually @file{$PREFIX/share/avconv})
874 in that order. For example, if the argument is @code{libx264-max}, it will
875 search for the file @file{libx264-max.avpreset}.
877 @section Video and Audio grabbing
879 If you specify the input format and device then avconv can grab video
883 avconv -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg
886 Note that you must activate the right video source and channel before
887 launching avconv with any TV viewer such as
888 @uref{http://linux.bytesex.org/xawtv/, xawtv} by Gerd Knorr. You also
889 have to set the audio recording levels correctly with a
892 @section X11 grabbing
894 Grab the X11 display with avconv via
897 avconv -f x11grab -s cif -r 25 -i :0.0 /tmp/out.mpg
900 0.0 is display.screen number of your X11 server, same as
901 the DISPLAY environment variable.
904 avconv -f x11grab -s cif -r 25 -i :0.0+10,20 /tmp/out.mpg
907 0.0 is display.screen number of your X11 server, same as the DISPLAY environment
908 variable. 10 is the x-offset and 20 the y-offset for the grabbing.
910 @section Video and Audio file format conversion
912 Any supported file format and protocol can serve as input to avconv:
917 You can use YUV files as input:
920 avconv -i /tmp/test%d.Y /tmp/out.mpg
923 It will use the files:
925 /tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
926 /tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...
929 The Y files use twice the resolution of the U and V files. They are
930 raw files, without header. They can be generated by all decent video
931 decoders. You must specify the size of the image with the @option{-s} option
932 if avconv cannot guess it.
935 You can input from a raw YUV420P file:
938 avconv -i /tmp/test.yuv /tmp/out.avi
941 test.yuv is a file containing raw YUV planar data. Each frame is composed
942 of the Y plane followed by the U and V planes at half vertical and
943 horizontal resolution.
946 You can output to a raw YUV420P file:
949 avconv -i mydivx.avi hugefile.yuv
953 You can set several input files and output files:
956 avconv -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg
959 Converts the audio file a.wav and the raw YUV video file a.yuv
963 You can also do audio and video conversions at the same time:
966 avconv -i /tmp/a.wav -ar 22050 /tmp/a.mp2
969 Converts a.wav to MPEG audio at 22050 Hz sample rate.
972 You can encode to several formats at the same time and define a
973 mapping from input stream to output streams:
976 avconv -i /tmp/a.wav -map 0:a -b 64k /tmp/a.mp2 -map 0:a -b 128k /tmp/b.mp2
979 Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
980 file:index' specifies which input stream is used for each output
981 stream, in the order of the definition of output streams.
984 You can transcode decrypted VOBs:
987 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
990 This is a typical DVD ripping example; the input is a VOB file, the
991 output an AVI file with MPEG-4 video and MP3 audio. Note that in this
992 command we use B-frames so the MPEG-4 stream is DivX5 compatible, and
993 GOP size is 300 which means one intra frame every 10 seconds for 29.97fps
994 input video. Furthermore, the audio stream is MP3-encoded so you need
995 to enable LAME support by passing @code{--enable-libmp3lame} to configure.
996 The mapping is particularly useful for DVD transcoding
997 to get the desired audio language.
999 NOTE: To see the supported input formats, use @code{avconv -formats}.
1002 You can extract images from a video, or create a video from many images:
1004 For extracting images from a video:
1006 avconv -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg
1009 This will extract one video frame per second from the video and will
1010 output them in files named @file{foo-001.jpeg}, @file{foo-002.jpeg},
1011 etc. Images will be rescaled to fit the new WxH values.
1013 If you want to extract just a limited number of frames, you can use the
1014 above command in combination with the -vframes or -t option, or in
1015 combination with -ss to start extracting from a certain point in time.
1017 For creating a video from many images:
1019 avconv -f image2 -i foo-%03d.jpeg -r 12 -s WxH foo.avi
1022 The syntax @code{foo-%03d.jpeg} specifies to use a decimal number
1023 composed of three digits padded with zeroes to express the sequence
1024 number. It is the same syntax supported by the C printf function, but
1025 only formats accepting a normal integer are suitable.
1028 You can put many streams of the same type in the output:
1031 avconv -i test1.avi -i test2.avi -map 0.3 -map 0.2 -map 0.1 -map 0.0 -c copy test12.nut
1034 The resulting output file @file{test12.avi} will contain first four streams from
1035 the input file in reverse order.
1041 @include encoders.texi
1042 @include demuxers.texi
1043 @include muxers.texi
1044 @include indevs.texi
1045 @include outdevs.texi
1046 @include protocols.texi
1047 @include bitstream_filters.texi
1048 @include filters.texi
1049 @include metadata.texi
1054 @settitle avconv video converter
1056 @c man begin SEEALSO
1057 avplay(1), avprobe(1) and the Libav HTML documentation
1060 @c man begin AUTHORS
1061 The Libav developers