Synopsis
********

The generic syntax is:

     avconv [global options] [[infile options][-i INFILE]]... {[outfile options] OUTFILE}...

Description
***********

avconv is a very fast video and audio converter that can also grab from a live audio/video source. It can also convert between arbitrary sample rates and resize video on the fly with a high quality polyphase filter.

avconv reads from an arbitrary number of input "files" (which can be regular files, pipes, network streams, grabbing devices, etc.), specified by the -i option, and writes to an arbitrary number of output "files", which are specified by a plain output filename. Anything found on the command line which cannot be interpreted as an option is considered to be an output filename.

Each input or output file can in principle contain any number of streams of different types (video/audio/subtitle/attachment/data). Allowed number and/or types of streams can be limited by the container format. Selecting, which streams from which inputs go into output, is done either automatically or with the -map option (see the Stream selection chapter).

To refer to input files in options, you must use their indices (0-based). E.g. the first input file is 0, the second is 1 etc. Similarly, streams within a file are referred to by their indices. E.g. 2:3 refers to the fourth stream in the third input file. See also the Stream specifiers chapter.

As a general rule, options are applied to the next specified file. Therefore, order is important, and you can have the same option on the command line multiple times. Each occurrence is then applied to the next input or output file. Exceptions from this rule are the global options (e.g. verbosity level), which should be specified first.

Do not mix input and output files -- first specify all input files, then all output files. Also do not mix options which belong to different files. All options apply ONLY to the next input or output file and are reset between files.

  * To set the video bitrate of the output file to 64kbit/s:

          avconv -i input.avi -b 64k output.avi

  * To force the frame rate of the output file to 24 fps:

          avconv -i input.avi -r 24 output.avi

  * To force the frame rate of the input file (valid for raw formats only) to 1 fps and the frame rate of the output file to 24 fps:

          avconv -r 1 -i input.m2v -r 24 output.avi

The format option may be needed for raw input files.

Detailed description
********************

The transcoding process in avconv for each output can be described by the following diagram:

      _______              ______________
     |       |            |              |
     | input |  demuxer   | encoded data |   decoder
     | file  | ---------> | packets      | -----+
     |_______|            |______________|      |
                                                v
                                            _________
                                           |         |
                                           | decoded |
                                           | frames  |
                                           |_________|
      ________             ______________       |
     |        |           |              |      |
     | output | <-------- | encoded data | <----+
     | file   |   muxer   | packets      |   encoder
     |________|           |______________|

avconv calls the libavformat library (containing demuxers) to read input files and get packets containing encoded data from them. When there are multiple input files, avconv tries to keep them synchronized by tracking lowest timestamp on any active input stream.

Encoded packets are then passed to the decoder (unless streamcopy is selected for the stream, see further for a description). The decoder produces uncompressed frames (raw video/PCM audio/...) which can be processed further by filtering (see next section). After filtering the frames are passed to the encoder, which encodes them and outputs encoded packets again. Finally those are passed to the muxer, which writes the encoded packets to the output file.

Filtering
=========

Before encoding, avconv can process raw audio and video frames using filters from the libavfilter library. Several chained filters form a filter graph.  avconv distinguishes between two types of filtergraphs - simple and complex.

Simple filtergraphs
-------------------

Simple filtergraphs are those that have exactly one input and output, both of the same type. In the above diagram they can be represented by simply inserting an additional step between decoding and encoding:

      _________                        ______________
     |         |                      |              |
     | decoded |                      | encoded data |
     | frames  |\                    /| packets      |
     |_________| \                  / |______________|
                  \   __________   /
       simple      \ |          | /  encoder
       filtergraph  \| filtered |/
                     | frames   |
                     |__________|

Simple filtergraphs are configured with the per-stream -filter option (with -vf and -af aliases for video and audio respectively). A simple filtergraph for video can look for example like this:

      _______        _____________        _______        ________
     |       |      |             |      |       |      |        |
     | input | ---> | deinterlace | ---> | scale | ---> | output |
     |_______|      |_____________|      |_______|      |________|

Note that some filters change frame properties but not frame contents. E.g. the fps filter in the example above changes number of frames, but does not touch the frame contents. Another example is the setpts filter, which only sets timestamps and otherwise passes the frames unchanged.

Complex filtergraphs
--------------------

Complex filtergraphs are those which cannot be described as simply a linear processing chain applied to one stream. This is the case e.g. when the graph has more than one input and/or output, or when output stream type is different from input. They can be represented with the following diagram:

      _________
     |         |
     | input 0 |\                    __________
     |_________| \                  |          |
                  \   _________    /| output 0 |
                   \ |         |  / |__________|
      _________     \| complex | /
     |         |     |         |/
     | input 1 |---->| filter  |\
     |_________|     |         | \   __________
                    /| graph   |  \ |          |
                   / |         |   \| output 1 |
      _________   /  |_________|    |__________|
     |         | /
     | input 2 |/
     |_________|

Complex filtergraphs are configured with the -filter_complex option. Note that this option is global, since a complex filtergraph by its nature cannot be unambiguously associated with a single stream or file.

A trivial example of a complex filtergraph is the overlay filter, which has two video inputs and one video output, containing one video overlaid on top of the other. Its audio counterpart is the amix filter.

Stream copy
===========

Stream copy is a mode selected by supplying the copy parameter to the -codec option. It makes avconv omit the decoding and encoding step for the specified stream, so it does only demuxing and muxing. It is useful for changing the container format or modifying container-level metadata. The diagram above will in this case simplify to this:

      _______              ______________            ________
     |       |            |              |          |        |
     | input |  demuxer   | encoded data |  muxer   | output |
     | file  | ---------> | packets      | -------> | file   |
     |_______|            |______________|          |________|

Since there is no decoding or encoding, it is very fast and there is no quality loss. However it might not work in some cases because of many factors. Applying filters is obviously also impossible, since filters work on uncompressed data.

Stream selection
****************

By default avconv tries to pick the "best" stream of each type present in input files and add them to each output file. For video, this means the highest resolution, for audio the highest channel count. For subtitle it's simply the first subtitle stream.

You can disable some of those defaults by using -vn/-an/-sn options. For full manual control, use the -map option, which disables the defaults just described.

Options
*******

     [file avtools-common-opts.texi not included]

Main options
============

-f FMT (input/output)
     Force input or output file format. The format is normally autodetected for input files and guessed from file extension for output files, so this option is not needed in most cases.

-i FILENAME (input)
     input file name

-y (global)
     Overwrite output files without asking.

-n (global)
     Immediately exit when output files already exist.

-c[:STREAM_SPECIFIER] CODEC (input/output,per-stream)
-codec[:STREAM_SPECIFIER] CODEC (input/output,per-stream)
     Select an encoder (when used before an output file) or a decoder (when used before an input file) for one or more streams. CODEC is the name of a decoder/encoder or a special value copy (output only) to indicate that the stream is not to be reencoded.

     For example

          avconv -i INPUT -map 0 -c:v libx264 -c:a copy OUTPUT

     encodes all video streams with libx264 and copies all audio streams.

     For each stream, the last matching c option is applied, so

          avconv -i INPUT -map 0 -c copy -c:v:1 libx264 -c:a:137 libvorbis OUTPUT

     will copy all the streams except the second video, which will be encoded with libx264, and the 138th audio, which will be encoded with libvorbis.

-t DURATION (output)
     Stop writing the output after its duration reaches DURATION. DURATION may be a number in seconds, or in hh:mm:ss[.xxx] form.

-fs LIMIT_SIZE (output)
     Set the file size limit.

-ss POSITION (input/output)
     When used as an input option (before -i), seeks in this input file to POSITION. Note the in most formats it is not possible to seek exactly, so avconv will seek to the closest seek point before POSITION. When transcoding and -accurate_seek is enabled (the default), this extra segment between the seek point and POSITION will be decoded and discarded. When doing stream copy or when -noaccurate_seek is used, it will be preserved.

     When used as an output option (before an output filename), decodes but discards input until the timestamps reach POSITION.

     POSITION may be either in seconds or in hh:mm:ss[.xxx] form.

-itsoffset OFFSET (input)
     Set the input time offset in seconds. [-]hh:mm:ss[.xxx] syntax is also supported. The offset is added to the timestamps of the input files. Specifying a positive offset means that the corresponding streams are delayed by OFFSET seconds.

-metadata[:metadata_specifier] KEY=VALUE (output,per-metadata)
     Set a metadata key/value pair.

     An optional METADATA_SPECIFIER may be given to set metadata on streams or chapters. See -map_metadata documentation for details.

     This option overrides metadata set with -map_metadata. It is also possible to delete metadata by using an empty value.

     For example, for setting the title in the output file:

          avconv -i in.avi -metadata title="my title" out.flv

     To set the language of the first audio stream:

          avconv -i INPUT -metadata:s:a:0 language=eng OUTPUT

-target TYPE (output)
     Specify target file type (vcd, svcd, dvd, dv, dv50). TYPE may be prefixed with pal-, ntsc- or film- to use the corresponding standard. All the format options (bitrate, codecs, buffer sizes) are then set automatically. You can just type:

          avconv -i myfile.avi -target vcd /tmp/vcd.mpg

     Nevertheless you can specify additional options as long as you know they do not conflict with the standard, as in:

          avconv -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg

-dframes NUMBER (output)
     Set the number of data frames to record. This is an alias for -frames:d.

-frames[:STREAM_SPECIFIER] FRAMECOUNT (output,per-stream)
     Stop writing to the stream after FRAMECOUNT frames.

-q[:STREAM_SPECIFIER] Q (output,per-stream)
-qscale[:STREAM_SPECIFIER] Q (output,per-stream)
     Use fixed quality scale (VBR). The meaning of Q is codec-dependent.

-filter[:STREAM_SPECIFIER] FILTER_GRAPH (output,per-stream)
     FILTER_GRAPH is a description of the filter graph to apply to the stream. Use -filters to show all the available filters (including also sources and sinks).

     See also the -filter_complex option if you want to create filter graphs with multiple inputs and/or outputs.

-filter_script[:STREAM_SPECIFIER] FILENAME (output,per-stream)
     This option is similar to -filter, the only difference is that its argument is the name of the file from which a filtergraph description is to be read.

-pre[:STREAM_SPECIFIER] PRESET_NAME (output,per-stream)
     Specify the preset for matching stream(s).

-stats (global)
     Print encoding progress/statistics. On by default.

-attach FILENAME (output)
     Add an attachment to the output file. This is supported by a few formats like Matroska for e.g. fonts used in rendering subtitles. Attachments are implemented as a specific type of stream, so this option will add a new stream to the file. It is then possible to use per-stream options on this stream in the usual way. Attachment streams created with this option will be created after all the other streams (i.e. those created with -map or automatic mappings).

     Note that for Matroska you also have to set the mimetype metadata tag:

          avconv -i INPUT -attach DejaVuSans.ttf -metadata:s:2 mimetype=application/x-truetype-font out.mkv

     (assuming that the attachment stream will be third in the output file).

-dump_attachment[:STREAM_SPECIFIER] FILENAME (input,per-stream)
     Extract the matching attachment stream into a file named FILENAME. If FILENAME is empty, then the value of the filename metadata tag will be used.

     E.g. to extract the first attachment to a file named 'out.ttf':

          avconv -dump_attachment:t:0 out.ttf INPUT

     To extract all attachments to files determined by the filename tag:

          avconv -dump_attachment:t "" INPUT

     Technical note -- attachments are implemented as codec extradata, so this option can actually be used to extract extradata from any stream, not just attachments.

Video Options
=============

-vframes NUMBER (output)
     Set the number of video frames to record. This is an alias for -frames:v.

-r[:STREAM_SPECIFIER] FPS (input/output,per-stream)
     Set frame rate (Hz value, fraction or abbreviation).

     As an input option, ignore any timestamps stored in the file and instead generate timestamps assuming constant frame rate FPS.

     As an output option, duplicate or drop input frames to achieve constant output frame rate FPS (note that this actually causes the fps filter to be inserted to the end of the corresponding filtergraph).

-s[:STREAM_SPECIFIER] SIZE (input/output,per-stream)
     Set frame size.

     As an input option, this is a shortcut for the video_size private option, recognized by some demuxers for which the frame size is either not stored in the file or is configurable -- e.g. raw video or video grabbers.

     As an output option, this inserts the scale video filter to the end of the corresponding filtergraph. Please use the scale filter directly to insert it at the beginning or some other place.

     The format is wxh (default - same as source).  The following abbreviations are recognized:

     sqcif
          128x96

     qcif
          176x144

     cif
          352x288

     4cif
          704x576

     16cif
          1408x1152

     qqvga
          160x120

     qvga
          320x240

     vga
          640x480

     svga
          800x600

     xga
          1024x768

     uxga
          1600x1200

     qxga
          2048x1536

     sxga
          1280x1024

     qsxga
          2560x2048

     hsxga
          5120x4096

     wvga
          852x480

     wxga
          1366x768

     wsxga
          1600x1024

     wuxga
          1920x1200

     woxga
          2560x1600

     wqsxga
          3200x2048

     wquxga
          3840x2400

     whsxga
          6400x4096

     whuxga
          7680x4800

     cga
          320x200

     ega
          640x350

     hd480
          852x480

     hd720
          1280x720

     hd1080
          1920x1080

-aspect[:STREAM_SPECIFIER] ASPECT (output,per-stream)
     Set the video display aspect ratio specified by ASPECT.

     ASPECT can be a floating point number string, or a string of the form NUM:DEN, where NUM and DEN are the numerator and denominator of the aspect ratio. For example "4:3", "16:9", "1.3333", and "1.7777" are valid argument values.

-vn (output)
     Disable video recording.

-vcodec CODEC (output)
     Set the video codec. This is an alias for -codec:v.

-pass[:STREAM_SPECIFIER] N (output,per-stream)
     Select the pass number (1 or 2). It is used to do two-pass video encoding. The statistics of the video are recorded in the first pass into a log file (see also the option -passlogfile), and in the second pass that log file is used to generate the video at the exact requested bitrate. On pass 1, you may just deactivate audio and set output to null, examples for Windows and Unix:

          avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y NUL
          avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null

-passlogfile[:STREAM_SPECIFIER] PREFIX (output,per-stream)
     Set two-pass log file name prefix to PREFIX, the default file name prefix is ``av2pass''. The complete file name will be PREFIX-N.log, where N is a number specific to the output stream.

-vf FILTER_GRAPH (output)
     FILTER_GRAPH is a description of the filter graph to apply to the input video. Use the option "-filters" to show all the available filters (including also sources and sinks).  This is an alias for -filter:v.

Advanced Video Options
======================

-pix_fmt[:STREAM_SPECIFIER] FORMAT (input/output,per-stream)
     Set pixel format. Use -pix_fmts to show all the supported pixel formats.

-sws_flags FLAGS (input/output)
     Set SwScaler flags.

-vdt N
     Discard threshold.

-rc_override[:STREAM_SPECIFIER] OVERRIDE (output,per-stream)
     rate control override for specific intervals

-vstats
     Dump video coding statistics to vstats_HHMMSS.log.

-vstats_file FILE
     Dump video coding statistics to FILE.

-top[:STREAM_SPECIFIER] N (output,per-stream)
     top=1/bottom=0/auto=-1 field first

-dc PRECISION
     Intra_dc_precision.

-vtag FOURCC/TAG (output)
     Force video tag/fourcc. This is an alias for -tag:v.

-qphist (global)
     Show QP histogram.

-force_key_frames[:STREAM_SPECIFIER] TIME[,TIME...] (output,per-stream)
     Force key frames at the specified timestamps, more precisely at the first frames after each specified time. This option can be useful to ensure that a seek point is present at a chapter mark or any other designated place in the output file. The timestamps must be specified in ascending order.

-copyinkf[:STREAM_SPECIFIER] (output,per-stream)
     When doing stream copy, copy also non-key frames found at the beginning.

-hwaccel[:STREAM_SPECIFIER] HWACCEL (input,per-stream)
     Use hardware acceleration to decode the matching stream(s). The allowed values of HWACCEL are:

     none
          Do not use any hardware acceleration (the default).

     auto
          Automatically select the hardware acceleration method.

     vda
          Use Apple VDA hardware acceleration.

     vdpau
          Use VDPAU (Video Decode and Presentation API for Unix) hardware acceleration.

     dxva2
          Use DXVA2 (DirectX Video Acceleration) hardware acceleration.

     This option has no effect if the selected hwaccel is not available or not supported by the chosen decoder.

     Note that most acceleration methods are intended for playback and will not be faster than software decoding on modern CPUs. Additionally, avconv will usually need to copy the decoded frames from the GPU memory into the system memory, resulting in further performance loss. This option is thus mainly useful for testing.

-hwaccel_device[:STREAM_SPECIFIER] HWACCEL_DEVICE (input,per-stream)
     Select a device to use for hardware acceleration.

     This option only makes sense when the -hwaccel option is also specified. Its exact meaning depends on the specific hardware acceleration method chosen.

     vdpau
          For VDPAU, this option specifies the X11 display/screen to use. If this option is not specified, the value of the DISPLAY environment variable is used

     dxva2
          For DXVA2, this option should contain the number of the display adapter to use. If this option is not specified, the default adapter is used.

Audio Options
=============

-aframes NUMBER (output)
     Set the number of audio frames to record. This is an alias for -frames:a.

-ar[:STREAM_SPECIFIER] FREQ (input/output,per-stream)
     Set the audio sampling frequency. For output streams it is set by default to the frequency of the corresponding input stream. For input streams this option only makes sense for audio grabbing devices and raw demuxers and is mapped to the corresponding demuxer options.

-aq Q (output)
     Set the audio quality (codec-specific, VBR). This is an alias for -q:a.

-ac[:STREAM_SPECIFIER] CHANNELS (input/output,per-stream)
     Set the number of audio channels. For output streams it is set by default to the number of input audio channels. For input streams this option only makes sense for audio grabbing devices and raw demuxers and is mapped to the corresponding demuxer options.

-an (output)
     Disable audio recording.

-acodec CODEC (input/output)
     Set the audio codec. This is an alias for -codec:a.

-sample_fmt[:STREAM_SPECIFIER] SAMPLE_FMT (output,per-stream)
     Set the audio sample format. Use -sample_fmts to get a list of supported sample formats.

-af FILTER_GRAPH (output)
     FILTER_GRAPH is a description of the filter graph to apply to the input audio. Use the option "-filters" to show all the available filters (including also sources and sinks).  This is an alias for -filter:a.

Advanced Audio options:
=======================

-atag FOURCC/TAG (output)
     Force audio tag/fourcc. This is an alias for -tag:a.

Subtitle options:
=================

-scodec CODEC (input/output)
     Set the subtitle codec. This is an alias for -codec:s.

-sn (output)
     Disable subtitle recording.

Advanced options
================

-map [-]INPUT_FILE_ID[:STREAM_SPECIFIER][,SYNC_FILE_ID[:STREAM_SPECIFIER]] | [LINKLABEL] (output)

     Designate one or more input streams as a source for the output file. Each input stream is identified by the input file index INPUT_FILE_ID and the input stream index INPUT_STREAM_ID within the input file. Both indices start at 0. If specified, SYNC_FILE_ID:STREAM_SPECIFIER sets which input stream is used as a presentation sync reference.

     The first -map option on the command line specifies the source for output stream 0, the second -map option specifies the source for output stream 1, etc.

     A - character before the stream identifier creates a "negative" mapping. It disables matching streams from already created mappings.

     An alternative [LINKLABEL] form will map outputs from complex filter graphs (see the -filter_complex option) to the output file. LINKLABEL must correspond to a defined output link label in the graph.

     For example, to map ALL streams from the first input file to output

          avconv -i INPUT -map 0 output

     For example, if you have two audio streams in the first input file, these streams are identified by "0:0" and "0:1". You can use -map to select which streams to place in an output file. For example:

          avconv -i INPUT -map 0:1 out.wav

     will map the input stream in INPUT identified by "0:1" to the (single) output stream in out.wav.

     For example, to select the stream with index 2 from input file a.mov (specified by the identifier "0:2"), and stream with index 6 from input b.mov (specified by the identifier "1:6"), and copy them to the output file out.mov:

          avconv -i a.mov -i b.mov -c copy -map 0:2 -map 1:6 out.mov

     To select all video and the third audio stream from an input file:

          avconv -i INPUT -map 0:v -map 0:a:2 OUTPUT

     To map all the streams except the second audio, use negative mappings

          avconv -i INPUT -map 0 -map -0:a:1 OUTPUT

     To pick the English audio stream:

          avconv -i INPUT -map 0:m:language:eng OUTPUT

     Note that using this option disables the default mappings for this output file.

-map_metadata[:METADATA_SPEC_OUT] INFILE[:METADATA_SPEC_IN] (output,per-metadata)
     Set metadata information of the next output file from INFILE. Note that those are file indices (zero-based), not filenames. Optional METADATA_SPEC_IN/OUT parameters specify, which metadata to copy. A metadata specifier can have the following forms:

     G
          global metadata, i.e. metadata that applies to the whole file

     S[:STREAM_SPEC]
          per-stream metadata. STREAM_SPEC is a stream specifier as described in the Stream specifiers chapter. In an input metadata specifier, the first matching stream is copied from. In an output metadata specifier, all matching streams are copied to.

     C:CHAPTER_INDEX
          per-chapter metadata. CHAPTER_INDEX is the zero-based chapter index.

     P:PROGRAM_INDEX
          per-program metadata. PROGRAM_INDEX is the zero-based program index.

     If metadata specifier is omitted, it defaults to global.

     By default, global metadata is copied from the first input file, per-stream and per-chapter metadata is copied along with streams/chapters. These default mappings are disabled by creating any mapping of the relevant type. A negative file index can be used to create a dummy mapping that just disables automatic copying.

     For example to copy metadata from the first stream of the input file to global metadata of the output file:

          avconv -i in.ogg -map_metadata 0:s:0 out.mp3

     To do the reverse, i.e. copy global metadata to all audio streams:

          avconv -i in.mkv -map_metadata:s:a 0:g out.mkv

     Note that simple 0 would work as well in this example, since global metadata is assumed by default.

-map_chapters INPUT_FILE_INDEX (output)
     Copy chapters from input file with index INPUT_FILE_INDEX to the next output file. If no chapter mapping is specified, then chapters are copied from the first input file with at least one chapter. Use a negative file index to disable any chapter copying.

-debug
     Print specific debug info.

-benchmark (global)
     Show benchmarking information at the end of an encode. Shows CPU time used and maximum memory consumption. Maximum memory consumption is not supported on all systems, it will usually display as 0 if not supported.

-timelimit DURATION (global)
     Exit after avconv has been running for DURATION seconds.

-dump (global)
     Dump each input packet to stderr.

-hex (global)
     When dumping packets, also dump the payload.

-re (input)
     Read input at native frame rate. Mainly used to simulate a grab device or live input stream (e.g. when reading from a file). Should not be used with actual grab devices or live input streams (where it can cause packet loss).

-vsync PARAMETER
     Video sync method.

     passthrough
          Each frame is passed with its timestamp from the demuxer to the muxer.

     cfr
          Frames will be duplicated and dropped to achieve exactly the requested constant framerate.

     vfr
          Frames are passed through with their timestamp or dropped so as to prevent 2 frames from having the same timestamp.

     auto
          Chooses between 1 and 2 depending on muxer capabilities. This is the default method.

     With -map you can select from which stream the timestamps should be taken. You can leave either video or audio unchanged and sync the remaining stream(s) to the unchanged one.

-async SAMPLES_PER_SECOND
     Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps, the parameter is the maximum samples per second by which the audio is changed. -async 1 is a special case where only the start of the audio stream is corrected without any later correction. This option has been deprecated. Use the asyncts audio filter instead.

-copyts
     Copy timestamps from input to output.

-copytb
     Copy input stream time base from input to output when stream copying.

-shortest (output)
     Finish encoding when the shortest input stream ends.

-dts_delta_threshold
     Timestamp discontinuity delta threshold.

-muxdelay SECONDS (input)
     Set the maximum demux-decode delay.

-muxpreload SECONDS (input)
     Set the initial demux-decode delay.

-streamid OUTPUT-STREAM-INDEX:NEW-VALUE (output)
     Assign a new stream-id value to an output stream. This option should be specified prior to the output filename to which it applies. For the situation where multiple output files exist, a streamid may be reassigned to a different value.

     For example, to set the stream 0 PID to 33 and the stream 1 PID to 36 for an output mpegts file:

          avconv -i infile -streamid 0:33 -streamid 1:36 out.ts

-bsf[:STREAM_SPECIFIER] BITSTREAM_FILTERS (output,per-stream)
     Set bitstream filters for matching streams. BISTREAM_FILTERS is a comma-separated list of bitstream filters. Use the -bsfs option to get the list of bitstream filters.

          avconv -i h264.mp4 -c:v copy -bsf:v h264_mp4toannexb -an out.h264

          avconv -i file.mov -an -vn -bsf:s mov2textsub -c:s copy -f rawvideo sub.txt

-tag[:STREAM_SPECIFIER] CODEC_TAG (input/output,per-stream)
     Force a tag/fourcc for matching streams.

-filter_complex FILTERGRAPH (global)
     Define a complex filter graph, i.e. one with arbitrary number of inputs and/or outputs. For simple graphs -- those with one input and one output of the same type -- see the -filter options. FILTERGRAPH is a description of the filter graph, as described in Filtergraph syntax.

     Input link labels must refer to input streams using the [file_index:stream_specifier] syntax (i.e. the same as -map uses). If STREAM_SPECIFIER matches multiple streams, the first one will be used. An unlabeled input will be connected to the first unused input stream of the matching type.

     Output link labels are referred to with -map. Unlabeled outputs are added to the first output file.

     Note that with this option it is possible to use only lavfi sources without normal input files.

     For example, to overlay an image over video

          avconv -i video.mkv -i image.png -filter_complex '[0:v][1:v]overlay[out]' -map
          '[out]' out.mkv

     Here [0:v] refers to the first video stream in the first input file, which is linked to the first (main) input of the overlay filter. Similarly the first video stream in the second input is linked to the second (overlay) input of overlay.

     Assuming there is only one video stream in each input file, we can omit input labels, so the above is equivalent to

          avconv -i video.mkv -i image.png -filter_complex 'overlay[out]' -map
          '[out]' out.mkv

     Furthermore we can omit the output label and the single output from the filter graph will be added to the output file automatically, so we can simply write

          avconv -i video.mkv -i image.png -filter_complex 'overlay' out.mkv

     To generate 5 seconds of pure red video using lavfi color source:

          avconv -filter_complex 'color=red' -t 5 out.mkv

-filter_complex_script FILENAME (global)
     This option is similar to -filter_complex, the only difference is that its argument is the name of the file from which a complex filtergraph description is to be read.

-accurate_seek (input)
     This option enables or disables accurate seeking in input files with the -ss option. It is enabled by default, so seeking is accurate when transcoding. Use -noaccurate_seek to disable it, which may be useful e.g. when copying some streams and transcoding the others.

Tips
****

  * For streaming at very low bitrate application, use a low frame rate and a small GOP size. This is especially true for RealVideo where the Linux player does not seem to be very fast, so it can miss frames. An example is:

          avconv -g 3 -r 3 -t 10 -b 50k -s qcif -f rv10 /tmp/b.rm

  * The parameter 'q' which is displayed while encoding is the current quantizer. The value 1 indicates that a very good quality could be achieved. The value 31 indicates the worst quality. If q=31 appears too often, it means that the encoder cannot compress enough to meet your bitrate. You must either increase the bitrate, decrease the frame rate or decrease the frame size.

  * If your computer is not fast enough, you can speed up the compression at the expense of the compression ratio. You can use '-me zero' to speed up motion estimation, and '-g 0' to disable motion estimation completely (you have only I-frames, which means it is about as good as JPEG compression).

  * To have very low audio bitrates, reduce the sampling frequency (down to 22050 Hz for MPEG audio, 22050 or 11025 for AC-3).

  * To have a constant quality (but a variable bitrate), use the option '-qscale n' when 'n' is between 1 (excellent quality) and 31 (worst quality).

Examples
********

Preset files
============

A preset file contains a sequence of OPTION=VALUE pairs, one for each line, specifying a sequence of options which can be specified also on the command line. Lines starting with the hash ('#') character are ignored and are used to provide comments. Empty lines are also ignored. Check the presets directory in the Libav source tree for examples.

Preset files are specified with the pre option, this option takes a preset name as input.  Avconv searches for a file named PRESET_NAME.avpreset in the directories $AVCONV_DATADIR (if set), and $HOME/.avconv, and in the data directory defined at configuration time (usually $PREFIX/share/avconv) in that order.  For example, if the argument is libx264-max, it will search for the file libx264-max.avpreset.

Video and Audio grabbing
========================

If you specify the input format and device then avconv can grab video and audio directly.

     avconv -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg

Note that you must activate the right video source and channel before launching avconv with any TV viewer such as xawtv (http://linux.bytesex.org/xawtv/) by Gerd Knorr. You also have to set the audio recording levels correctly with a standard mixer.

X11 grabbing
============

Grab the X11 display with avconv via

     avconv -f x11grab -s cif -r 25 -i :0.0 /tmp/out.mpg

0.0 is display.screen number of your X11 server, same as the DISPLAY environment variable.

     avconv -f x11grab -s cif -r 25 -i :0.0+10,20 /tmp/out.mpg

0.0 is display.screen number of your X11 server, same as the DISPLAY environment variable. 10 is the x-offset and 20 the y-offset for the grabbing.

Video and Audio file format conversion
======================================

Any supported file format and protocol can serve as input to avconv:

Examples:

  * You can use YUV files as input:

          avconv -i /tmp/test%d.Y /tmp/out.mpg

     It will use the files:

          /tmp/test0.Y, /tmp/test0.U, /tmp/test0.V,
          /tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc...

     The Y files use twice the resolution of the U and V files. They are raw files, without header. They can be generated by all decent video decoders. You must specify the size of the image with the -s option if avconv cannot guess it.

  * You can input from a raw YUV420P file:

          avconv -i /tmp/test.yuv /tmp/out.avi

     test.yuv is a file containing raw YUV planar data. Each frame is composed of the Y plane followed by the U and V planes at half vertical and horizontal resolution.

  * You can output to a raw YUV420P file:

          avconv -i mydivx.avi hugefile.yuv

  * You can set several input files and output files:

          avconv -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg

     Converts the audio file a.wav and the raw YUV video file a.yuv to MPEG file a.mpg.

  * You can also do audio and video conversions at the same time:

          avconv -i /tmp/a.wav -ar 22050 /tmp/a.mp2

     Converts a.wav to MPEG audio at 22050 Hz sample rate.

  * You can encode to several formats at the same time and define a mapping from input stream to output streams:

          avconv -i /tmp/a.wav -map 0:a -b 64k /tmp/a.mp2 -map 0:a -b 128k /tmp/b.mp2

     Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map file:index' specifies which input stream is used for each output stream, in the order of the definition of output streams.

  * You can transcode decrypted VOBs:

          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

     This is a typical DVD ripping example; the input is a VOB file, the output an AVI file with MPEG-4 video and MP3 audio. Note that in this command we use B-frames so the MPEG-4 stream is DivX5 compatible, and GOP size is 300 which means one intra frame every 10 seconds for 29.97fps input video. Furthermore, the audio stream is MP3-encoded so you need to enable LAME support by passing --enable-libmp3lame to configure. The mapping is particularly useful for DVD transcoding to get the desired audio language.

     NOTE: To see the supported input formats, use avconv -formats.

  * You can extract images from a video, or create a video from many images:

     For extracting images from a video:

          avconv -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg

     This will extract one video frame per second from the video and will output them in files named foo-001.jpeg, foo-002.jpeg, etc. Images will be rescaled to fit the new WxH values.

     If you want to extract just a limited number of frames, you can use the above command in combination with the -vframes or -t option, or in combination with -ss to start extracting from a certain point in time.

     For creating a video from many images:

          avconv -f image2 -i foo-%03d.jpeg -r 12 -s WxH foo.avi

     The syntax foo-%03d.jpeg specifies to use a decimal number composed of three digits padded with zeroes to express the sequence number. It is the same syntax supported by the C printf function, but only formats accepting a normal integer are suitable.

  * You can put many streams of the same type in the output:

          avconv -i test1.avi -i test2.avi -map 1:1 -map 1:0 -map 0:1 -map 0:0 -c copy -y test12.nut

     The resulting output file test12.nut will contain the first four streams from the input files in reverse order.

  * To force CBR video output:

          avconv -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v

  * The four options lmin, lmax, mblmin and mblmax use 'lambda' units, but you may use the QP2LAMBDA constant to easily convert from 'q' units:

          avconv -i src.ext -lmax 21*QP2LAMBDA dst.ext

     [file eval.texi not included]
     [file decoders.texi not included]
     [file encoders.texi not included]
     [file demuxers.texi not included]
     [file muxers.texi not included]
     [file indevs.texi not included]
     [file outdevs.texi not included]
     [file protocols.texi not included]
     [file bitstream_filters.texi not included]
     [file filters.texi not included]
     [file metadata.texi not included]