Provided by: libav-tools_9.20-0ubuntu0.14.04.1_amd64 bug

NAME

       avconv - avconv video converter

SYNOPSIS

       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   | decoded |  encoder   | encoded data |  muxer   | output |
               | file  | ---------> | packets      |  ---------> | frames  | ---------> | packets      | -------> | file   |
               |_______|            |______________|             |_________|            |______________|          |________|

       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 |  simple filtergraph  | filtered |  encoder   | encoded data |
               | frames  | -------------------> | frames   | ---------> | packets      |
               |_________|                      |__________|            |______________|

       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 | ---> | fps | ---> | 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

       All the numerical options, if not specified otherwise, accept in input a string representing a number,
       which may contain one of the SI unit prefixes, for example 'K', 'M', 'G'.  If 'i' is appended after the
       prefix, binary prefixes are used, which are based on powers of 1024 instead of powers of 1000.  The 'B'
       postfix multiplies the value by 8, and can be appended after a unit prefix or used alone. This allows
       using for example 'KB', 'MiB', 'G' and 'B' as number postfix.

       Options which do not take arguments are boolean options, and set the corresponding value to true. They
       can be set to false by prefixing with "no" the option name, for example using "-nofoo" in the command
       line will set to false the boolean option with name "foo".

   Stream specifiers
       Some options are applied per-stream, e.g. bitrate or codec. Stream specifiers are used to precisely
       specify which stream(s) does a given option belong to.

       A stream specifier is a string generally appended to the option name and separated from it by a colon.
       E.g. "-codec:a:1 ac3" option contains "a:1" stream specifer, which matches the second audio stream.
       Therefore it would select the ac3 codec for the second audio stream.

       A stream specifier can match several stream, the option is then applied to all of them. E.g. the stream
       specifier in "-b:a 128k" matches all audio streams.

       An empty stream specifier matches all streams, for example "-codec copy" or "-codec: copy" would copy all
       the streams without reencoding.

       Possible forms of stream specifiers are:

       stream_index
           Matches the stream with this index. E.g. "-threads:1 4" would set the thread count for the second
           stream to 4.

       stream_type[:stream_index]
           stream_type is one of: 'v' for video, 'a' for audio, 's' for subtitle, 'd' for data and 't' for
           attachments. If stream_index is given, then matches stream number stream_index of this type.
           Otherwise matches all streams of this type.

       p:program_id[:stream_index]
           If stream_index is given, then matches stream number stream_index in program with id program_id.
           Otherwise matches all streams in this program.

   Generic options
       These options are shared amongst the av* tools.

       -L  Show license.

       -h, -?, -help, --help [arg]
           Show help. An optional parameter may be specified to print help about a specific item.

           Possible values of arg are:

           decoder=decoder_name
               Print detailed information about the decoder named decoder_name. Use the -decoders option to get
               a list of all decoders.

           encoder=encoder_name
               Print detailed information about the encoder named encoder_name. Use the -encoders option to get
               a list of all encoders.

           demuxer=demuxer_name
               Print detailed information about the demuxer named demuxer_name. Use the -formats option to get a
               list of all demuxers and muxers.

           muxer=muxer_name
               Print detailed information about the muxer named muxer_name. Use the -formats option to get a
               list of all muxers and demuxers.

       -version
           Show version.

       -formats
           Show available formats.

           The fields preceding the format names have the following meanings:

           D   Decoding available

           E   Encoding available

       -codecs
           Show all codecs known to libavcodec.

           Note that the term 'codec' is used throughout this documentation as a shortcut for what is more
           correctly called a media bitstream format.

       -decoders
           Show available decoders.

       -encoders
           Show all available encoders.

       -bsfs
           Show available bitstream filters.

       -protocols
           Show available protocols.

       -filters
           Show available libavfilter filters.

       -pix_fmts
           Show available pixel formats.

       -sample_fmts
           Show available sample formats.

       -loglevel loglevel | -v loglevel
           Set the logging level used by the library.  loglevel is a number or a string containing one of the
           following values:

           quiet
           panic
           fatal
           error
           warning
           info
           verbose
           debug

           By default the program logs to stderr, if coloring is supported by the terminal, colors are used to
           mark errors and warnings. Log coloring can be disabled setting the environment variable
           AV_LOG_FORCE_NOCOLOR or NO_COLOR, or can be forced setting the environment variable
           AV_LOG_FORCE_COLOR.  The use of the environment variable NO_COLOR is deprecated and will be dropped
           in a following Libav version.

   AVOptions
       These options are provided directly by the libavformat, libavdevice and libavcodec libraries. To see the
       list of available AVOptions, use the -help option. They are separated into two categories:

       generic
           These options can be set for any container, codec or device. Generic options are listed under
           AVFormatContext options for containers/devices and under AVCodecContext options for codecs.

       private
           These options are specific to the given container, device or codec. Private options are listed under
           their corresponding containers/devices/codecs.

       For example to write an ID3v2.3 header instead of a default ID3v2.4 to an MP3 file, use the id3v2_version
       private option of the MP3 muxer:

               avconv -i input.flac -id3v2_version 3 out.mp3

       All codec AVOptions are obviously per-stream, so the chapter on stream specifiers applies to them

       Note -nooption syntax cannot be used for boolean AVOptions, use -option 0/-option 1.

       Note2 old undocumented way of specifying per-stream AVOptions by prepending v/a/s to the options name is
       now obsolete and will be removed soon.

   Codec AVOptions
       -b[:stream_specifier] integer (output,audio,video)
           set bitrate (in bits/s)

       -bt[:stream_specifier] integer (output,video)
           Set video bitrate tolerance (in bits/s). In 1-pass mode, bitrate tolerance specifies how far
           ratecontrol is willing to deviate from the target average bitrate value. This is not related to
           minimum/maximum bitrate. Lowering tolerance too much has an adverse effect on quality.

       -flags[:stream_specifier] flags (input/output,audio,video)
           Possible values:

           mv4 use four motion vectors per macroblock (MPEG-4)

           qpel
               use 1/4-pel motion compensation

           loop
               use loop filter

           qscale
               use fixed qscale

           gmc use gmc

           mv0 always try a mb with mv=<0,0>

           input_preserved
           pass1
               use internal 2-pass ratecontrol in first  pass mode

           pass2
               use internal 2-pass ratecontrol in second pass mode

           gray
               only decode/encode grayscale

           emu_edge
               do not draw edges

           psnr
               error[?] variables will be set during encoding

           truncated
           naq normalize adaptive quantization

           ildct
               use interlaced DCT

           low_delay
               force low delay

           global_header
               place global headers in extradata instead of every keyframe

           bitexact
               use only bitexact functions (except (I)DCT)

           aic H.263 advanced intra coding / MPEG-4 AC prediction

           cbp Deprecated, use mpegvideo private options instead

           qprd
               Deprecated, use mpegvideo private options instead

           ilme
               interlaced motion estimation

           cgop
               closed GOP

       -sub_id[:stream_specifier] integer ()
       -me_method[:stream_specifier] integer (output,video)
           set motion estimation method

           Possible values:

           zero
               zero motion estimation (fastest)

           full
               full motion estimation (slowest)

           epzs
               EPZS motion estimation (default)

           esa esa motion estimation (alias for full)

           tesa
               tesa motion estimation

           dia diamond motion estimation (alias for EPZS)

           log log motion estimation

           phods
               phods motion estimation

           x1  X1 motion estimation

           hex hex motion estimation

           umh umh motion estimation

           iter
               iter motion estimation

       -extradata_size[:stream_specifier] integer ()
       -time_base[:stream_specifier] rational number ()
       -g[:stream_specifier] integer (output,video)
           set the group of picture (GOP) size

       -ar[:stream_specifier] integer (input/output,audio)
           set audio sampling rate (in Hz)

       -ac[:stream_specifier] integer (input/output,audio)
           set number of audio channels

       -cutoff[:stream_specifier] integer (output,audio)
           set cutoff bandwidth

       -frame_size[:stream_specifier] integer (output,audio)
       -frame_number[:stream_specifier] integer ()
       -delay[:stream_specifier] integer ()
       -qcomp[:stream_specifier] float (output,video)
           video quantizer scale compression (VBR). Constant of ratecontrol equation. Recommended range for
           default rc_eq: 0.0-1.0

       -qblur[:stream_specifier] float (output,video)
           video quantizer scale blur (VBR)

       -qmin[:stream_specifier] integer (output,video)
           minimum video quantizer scale (VBR)

       -qmax[:stream_specifier] integer (output,video)
           maximum video quantizer scale (VBR)

       -qdiff[:stream_specifier] integer (output,video)
           maximum difference between the quantizer scales (VBR)

       -bf[:stream_specifier] integer (output,video)
           use 'frames' B frames

       -b_qfactor[:stream_specifier] float (output,video)
           QP factor between P- and B-frames

       -rc_strategy[:stream_specifier] integer (output,video)
           ratecontrol method

       -b_strategy[:stream_specifier] integer (output,video)
           strategy to choose between I/P/B-frames

       -ps[:stream_specifier] integer (output,video)
           RTP payload size in bytes

       -mv_bits[:stream_specifier] integer ()
       -header_bits[:stream_specifier] integer ()
       -i_tex_bits[:stream_specifier] integer ()
       -p_tex_bits[:stream_specifier] integer ()
       -i_count[:stream_specifier] integer ()
       -p_count[:stream_specifier] integer ()
       -skip_count[:stream_specifier] integer ()
       -misc_bits[:stream_specifier] integer ()
       -frame_bits[:stream_specifier] integer ()
       -codec_tag[:stream_specifier] integer ()
       -bug[:stream_specifier] flags (input,video)
           work around not autodetected encoder bugs

           Possible values:

           autodetect
           old_msmpeg4
               some old lavc-generated MSMPEG4v3 files (no autodetection)

           xvid_ilace
               Xvid interlacing bug (autodetected if FOURCC == XVIX)

           ump4
               (autodetected if FOURCC == UMP4)

           no_padding
               padding bug (autodetected)

           amv
           ac_vlc
               illegal VLC bug (autodetected per FOURCC)

           qpel_chroma
           std_qpel
               old standard qpel (autodetected per FOURCC/version)

           qpel_chroma2
           direct_blocksize
               direct-qpel-blocksize bug (autodetected per FOURCC/version)

           edge
               edge padding bug (autodetected per FOURCC/version)

           hpel_chroma
           dc_clip
           ms  work around various bugs in Microsoft's broken decoders

           trunc
               truncated frames

       -lelim[:stream_specifier] integer (output,video)
           single coefficient elimination threshold for luminance (negative values also consider DC coefficient)

       -celim[:stream_specifier] integer (output,video)
           single coefficient elimination threshold for chrominance (negative values also consider DC
           coefficient)

       -strict[:stream_specifier] integer (input/output,audio,video)
           how strictly to follow the standards

           Possible values:

           very
               strictly conform to a older more strict version of the spec or reference software

           strict
               strictly conform to all the things in the spec no matter what the consequences

           normal
           unofficial
               allow unofficial extensions

           experimental
               allow non-standardized experimental things

       -b_qoffset[:stream_specifier] float (output,video)
           QP offset between P- and B-frames

       -err_detect[:stream_specifier] flags (input,audio,video)
           set error detection flags

           Possible values:

           crccheck
               verify embedded CRCs

           bitstream
               detect bitstream specification deviations

           buffer
               detect improper bitstream length

           explode
               abort decoding on minor error detection

       -has_b_frames[:stream_specifier] integer ()
       -block_align[:stream_specifier] integer ()
       -mpeg_quant[:stream_specifier] integer (output,video)
           use MPEG quantizers instead of H.263

       -qsquish[:stream_specifier] float (output,video)
           how to keep quantizer between qmin and qmax (0 = clip, 1 = use differentiable function)

       -rc_qmod_amp[:stream_specifier] float (output,video)
           experimental quantizer modulation

       -rc_qmod_freq[:stream_specifier] integer (output,video)
           experimental quantizer modulation

       -rc_override_count[:stream_specifier] integer ()
       -rc_eq[:stream_specifier] string (output,video)
           Set rate control equation. When computing the expression, besides the standard functions defined in
           the section 'Expression Evaluation', the following functions are available: bits2qp(bits),
           qp2bits(qp). Also the following constants are available: iTex pTex tex mv fCode iCount mcVar var isI
           isP isB avgQP qComp avgIITex avgPITex avgPPTex avgBPTex avgTex.

       -maxrate[:stream_specifier] integer (output,audio,video)
           Set maximum bitrate tolerance (in bits/s). Requires bufsize to be set.

       -minrate[:stream_specifier] integer (output,audio,video)
           Set minimum bitrate tolerance (in bits/s). Most useful in setting up a CBR encode. It is of little
           use otherwise.

       -bufsize[:stream_specifier] integer (output,audio,video)
           set ratecontrol buffer size (in bits)

       -rc_buf_aggressivity[:stream_specifier] float (output,video)
           currently useless

       -i_qfactor[:stream_specifier] float (output,video)
           QP factor between P- and I-frames

       -i_qoffset[:stream_specifier] float (output,video)
           QP offset between P- and I-frames

       -rc_init_cplx[:stream_specifier] float (output,video)
           initial complexity for 1-pass encoding

       -dct[:stream_specifier] integer (output,video)
           DCT algorithm

           Possible values:

           auto
               autoselect a good one (default)

           fastint
               fast integer

           int accurate integer

           mmx
           altivec
           faan
               floating point AAN DCT

       -lumi_mask[:stream_specifier] float (output,video)
           compresses bright areas stronger than medium ones

       -tcplx_mask[:stream_specifier] float (output,video)
           temporal complexity masking

       -scplx_mask[:stream_specifier] float (output,video)
           spatial complexity masking

       -p_mask[:stream_specifier] float (output,video)
           inter masking

       -dark_mask[:stream_specifier] float (output,video)
           compresses dark areas stronger than medium ones

       -idct[:stream_specifier] integer (input/output,video)
           select IDCT implementation

           Possible values:

           auto
           int
           simple
           simplemmx
           mmi
           arm
           altivec
           sh4
           simplearm
           simplearmv5te
           simplearmv6
           simpleneon
           simplealpha
           h264
           vp3
           ipp
           xvidmmx
           faani
               floating point AAN IDCT

       -slice_count[:stream_specifier] integer ()
       -ec[:stream_specifier] flags (input,video)
           set error concealment strategy

           Possible values:

           guess_mvs
               iterative motion vector (MV) search (slow)

           deblock
               use strong deblock filter for damaged MBs

       -bits_per_coded_sample[:stream_specifier] integer ()
       -pred[:stream_specifier] integer (output,video)
           prediction method

           Possible values:

           left
           plane
           median
       -aspect[:stream_specifier] rational number (output,video)
           sample aspect ratio

       -debug[:stream_specifier] flags (input/output,audio,video,subtitles)
           print specific debug info

           Possible values:

           pict
               picture info

           rc  rate control

           bitstream
           mb_type
               macroblock (MB) type

           qp  per-block quantization parameter (QP)

           mv  motion vector

           dct_coeff
           skip
           startcode
           pts
           er  error recognition

           mmco
               memory management control operations (H.264)

           bugs
           vis_qp
               visualize quantization parameter (QP), lower QP are tinted greener

           vis_mb_type
               visualize block types

           buffers
               picture buffer allocations

           thread_ops
               threading operations

       -vismv[:stream_specifier] integer (input,video)
           visualize motion vectors (MVs)

           Possible values:

           pf  forward predicted MVs of P-frames

           bf  forward predicted MVs of B-frames

           bb  backward predicted MVs of B-frames

       -cmp[:stream_specifier] integer (output,video)
           full-pel ME compare function

           Possible values:

           sad sum of absolute differences, fast (default)

           sse sum of squared errors

           satd
               sum of absolute Hadamard transformed differences

           dct sum of absolute DCT transformed differences

           psnr
               sum of squared quantization errors (avoid, low quality)

           bit number of bits needed for the block

           rd  rate distortion optimal, slow

           zero
               0

           vsad
               sum of absolute vertical differences

           vsse
               sum of squared vertical differences

           nsse
               noise preserving sum of squared differences

           dctmax
           chroma
       -subcmp[:stream_specifier] integer (output,video)
           sub-pel ME compare function

           Possible values:

           sad sum of absolute differences, fast (default)

           sse sum of squared errors

           satd
               sum of absolute Hadamard transformed differences

           dct sum of absolute DCT transformed differences

           psnr
               sum of squared quantization errors (avoid, low quality)

           bit number of bits needed for the block

           rd  rate distortion optimal, slow

           zero
               0

           vsad
               sum of absolute vertical differences

           vsse
               sum of squared vertical differences

           nsse
               noise preserving sum of squared differences

           dctmax
           chroma
       -mbcmp[:stream_specifier] integer (output,video)
           macroblock compare function

           Possible values:

           sad sum of absolute differences, fast (default)

           sse sum of squared errors

           satd
               sum of absolute Hadamard transformed differences

           dct sum of absolute DCT transformed differences

           psnr
               sum of squared quantization errors (avoid, low quality)

           bit number of bits needed for the block

           rd  rate distortion optimal, slow

           zero
               0

           vsad
               sum of absolute vertical differences

           vsse
               sum of squared vertical differences

           nsse
               noise preserving sum of squared differences

           dctmax
           chroma
       -ildctcmp[:stream_specifier] integer (output,video)
           interlaced DCT compare function

           Possible values:

           sad sum of absolute differences, fast (default)

           sse sum of squared errors

           satd
               sum of absolute Hadamard transformed differences

           dct sum of absolute DCT transformed differences

           psnr
               sum of squared quantization errors (avoid, low quality)

           bit number of bits needed for the block

           rd  rate distortion optimal, slow

           zero
               0

           vsad
               sum of absolute vertical differences

           vsse
               sum of squared vertical differences

           nsse
               noise preserving sum of squared differences

           dctmax
           chroma
       -dia_size[:stream_specifier] integer (output,video)
           diamond type & size for motion estimation

       -last_pred[:stream_specifier] integer (output,video)
           amount of motion predictors from the previous frame

       -preme[:stream_specifier] integer (output,video)
           pre motion estimation

       -precmp[:stream_specifier] integer (output,video)
           pre motion estimation compare function

           Possible values:

           sad sum of absolute differences, fast (default)

           sse sum of squared errors

           satd
               sum of absolute Hadamard transformed differences

           dct sum of absolute DCT transformed differences

           psnr
               sum of squared quantization errors (avoid, low quality)

           bit number of bits needed for the block

           rd  rate distortion optimal, slow

           zero
               0

           vsad
               sum of absolute vertical differences

           vsse
               sum of squared vertical differences

           nsse
               noise preserving sum of squared differences

           dctmax
           chroma
       -pre_dia_size[:stream_specifier] integer (output,video)
           diamond type & size for motion estimation pre-pass

       -subq[:stream_specifier] integer (output,video)
           sub-pel motion estimation quality

       -dtg_active_format[:stream_specifier] integer ()
       -me_range[:stream_specifier] integer (output,video)
           limit motion vectors range (1023 for DivX player)

       -ibias[:stream_specifier] integer (output,video)
           intra quant bias

       -pbias[:stream_specifier] integer (output,video)
           inter quant bias

       -color_table_id[:stream_specifier] integer ()
       -global_quality[:stream_specifier] integer (output,audio,video)
       -coder[:stream_specifier] integer (output,video)
           Possible values:

           vlc variable length coder / Huffman coder

           ac  arithmetic coder

           raw raw (no encoding)

           rle run-length coder

           deflate
               deflate-based coder

       -context[:stream_specifier] integer (output,video)
           context model

       -slice_flags[:stream_specifier] integer ()
       -xvmc_acceleration[:stream_specifier] integer ()
       -mbd[:stream_specifier] integer (output,video)
           macroblock decision algorithm (high quality mode)

           Possible values:

           simple
               use mbcmp (default)

           bits
               use fewest bits

           rd  use best rate distortion

       -stream_codec_tag[:stream_specifier] integer ()
       -sc_threshold[:stream_specifier] integer (output,video)
           scene change threshold

       -lmin[:stream_specifier] integer (output,video)
           minimum Lagrange factor (VBR)

       -lmax[:stream_specifier] integer (output,video)
           maximum Lagrange factor (VBR)

       -nr[:stream_specifier] integer (output,video)
           noise reduction

       -rc_init_occupancy[:stream_specifier] integer (output,video)
           number of bits which should be loaded into the rc buffer before decoding starts

       -inter_threshold[:stream_specifier] integer (output,video)
       -flags2[:stream_specifier] flags (input/output,audio,video)
           Possible values:

           fast
               allow non-spec-compliant speedup tricks

           sgop
               Deprecated, use mpegvideo private options instead

           noout
               skip bitstream encoding

           local_header
               place global headers at every keyframe instead of in extradata

           skiprd
               Deprecated, use mpegvideo private options instead

       -error[:stream_specifier] integer (output,video)
       -qns[:stream_specifier] integer (output,video)
           deprecated, use mpegvideo private options instead

       -threads[:stream_specifier] integer (input/output,video)
           Possible values:

           auto
               autodetect a suitable number of threads to use

       -me_threshold[:stream_specifier] integer (output,video)
           motion estimation threshold

       -mb_threshold[:stream_specifier] integer (output,video)
           macroblock threshold

       -dc[:stream_specifier] integer (output,video)
           intra_dc_precision

       -nssew[:stream_specifier] integer (output,video)
           nsse weight

       -skip_top[:stream_specifier] integer (input,video)
           number of macroblock rows at the top which are skipped

       -skip_bottom[:stream_specifier] integer (input,video)
           number of macroblock rows at the bottom which are skipped

       -profile[:stream_specifier] integer (output,audio,video)
           Possible values:

           unknown
           aac_main
           aac_low
           aac_ssr
           aac_ltp
           aac_he
           aac_he_v2
           aac_ld
           aac_eld
           dts
           dts_es
           dts_96_24
           dts_hd_hra
           dts_hd_ma
       -level[:stream_specifier] integer (output,audio,video)
           Possible values:

           unknown
       -skip_threshold[:stream_specifier] integer (output,video)
           frame skip threshold

       -skip_factor[:stream_specifier] integer (output,video)
           frame skip factor

       -skip_exp[:stream_specifier] integer (output,video)
           frame skip exponent

       -skipcmp[:stream_specifier] integer (output,video)
           frame skip compare function

           Possible values:

           sad sum of absolute differences, fast (default)

           sse sum of squared errors

           satd
               sum of absolute Hadamard transformed differences

           dct sum of absolute DCT transformed differences

           psnr
               sum of squared quantization errors (avoid, low quality)

           bit number of bits needed for the block

           rd  rate distortion optimal, slow

           zero
               0

           vsad
               sum of absolute vertical differences

           vsse
               sum of squared vertical differences

           nsse
               noise preserving sum of squared differences

           dctmax
           chroma
       -border_mask[:stream_specifier] float (output,video)
           increase the quantizer for macroblocks close to borders

       -mblmin[:stream_specifier] integer (output,video)
           minimum macroblock Lagrange factor (VBR)

       -mblmax[:stream_specifier] integer (output,video)
           maximum macroblock Lagrange factor (VBR)

       -mepc[:stream_specifier] integer (output,video)
           motion estimation bitrate penalty compensation (1.0 = 256)

       -skip_loop_filter[:stream_specifier] integer (input,video)
           Possible values:

           none
           default
           noref
           bidir
           nokey
           all
       -skip_idct[:stream_specifier] integer (input,video)
           Possible values:

           none
           default
           noref
           bidir
           nokey
           all
       -skip_frame[:stream_specifier] integer (input,video)
           Possible values:

           none
           default
           noref
           bidir
           nokey
           all
       -bidir_refine[:stream_specifier] integer (output,video)
           refine the two motion vectors used in bidirectional macroblocks

       -brd_scale[:stream_specifier] integer (output,video)
           downscale frames for dynamic B-frame decision

       -keyint_min[:stream_specifier] integer (output,video)
           minimum interval between IDR-frames (x264)

       -refs[:stream_specifier] integer (output,video)
           reference frames to consider for motion compensation

       -chromaoffset[:stream_specifier] integer (output,video)
           chroma QP offset from luma

       -trellis[:stream_specifier] integer (output,audio,video)
           rate-distortion optimal quantization

       -sc_factor[:stream_specifier] integer (output,video)
           multiplied by qscale for each frame and added to scene_change_score

       -mv0_threshold[:stream_specifier] integer (output,video)
       -b_sensitivity[:stream_specifier] integer (output,video)
           adjust sensitivity of b_frame_strategy 1

       -compression_level[:stream_specifier] integer (output,audio,video)
       -min_prediction_order[:stream_specifier] integer (output,audio)
       -max_prediction_order[:stream_specifier] integer (output,audio)
       -timecode_frame_start[:stream_specifier] integer (output,video)
           GOP timecode frame start number, in non-drop-frame format

       -request_channels[:stream_specifier] integer (input,audio)
           set desired number of audio channels

       -bits_per_raw_sample[:stream_specifier] integer ()
       -channel_layout[:stream_specifier] integer (input/output,audio)
           Possible values:

       -request_channel_layout[:stream_specifier] integer (input,audio)
           Possible values:

       -rc_max_vbv_use[:stream_specifier] float (output,video)
       -rc_min_vbv_use[:stream_specifier] float (output,video)
       -ticks_per_frame[:stream_specifier] integer (input/output,audio,video)
       -color_primaries[:stream_specifier] integer (input/output,video)
       -color_trc[:stream_specifier] integer (input/output,video)
       -colorspace[:stream_specifier] integer (input/output,video)
       -color_range[:stream_specifier] integer (input/output,video)
       -chroma_sample_location[:stream_specifier] integer (input/output,video)
       -log_level_offset[:stream_specifier] integer ()
           set the log level offset

       -slices[:stream_specifier] integer (output,video)
           number of slices, used in parallelized encoding

       -thread_type[:stream_specifier] flags (input/output,video)
           select multithreading type

           Possible values:

           slice
           frame
       -audio_service_type[:stream_specifier] integer (output,audio)
           audio service type

           Possible values:

           ma  Main Audio Service

           ef  Effects

           vi  Visually Impaired

           hi  Hearing Impaired

           di  Dialogue

           co  Commentary

           em  Emergency

           vo  Voice Over

           ka  Karaoke

       -request_sample_fmt[:stream_specifier] integer (input,audio)
           Possible values:

           u8  8-bit unsigned integer

           s16 16-bit signed integer

           s32 32-bit signed integer

           flt 32-bit float

           dbl 64-bit double

           u8p 8-bit unsigned integer planar

           s16p
               16-bit signed integer planar

           s32p
               32-bit signed integer planar

           fltp
               32-bit float planar

           dblp
               64-bit double planar

   Format AVOptions
       -probesize integer (input)
           set probing size

       -packetsize integer (output)
           set packet size

       -fflags flags (input/output)
           Possible values:

           ignidx
               ignore index

           genpts
               generate pts

           nofillin
               do not fill in missing values that can be exactly calculated

           noparse
               disable AVParsers, this needs nofillin too

           igndts
               ignore dts

           discardcorrupt
               discard corrupted frames

           nobuffer
               reduce the latency introduced by optional buffering

       -analyzeduration integer (input)
           how many microseconds are analyzed to estimate duration

       -cryptokey hexadecimal string (input)
           decryption key

       -indexmem integer (input)
           max memory used for timestamp index (per stream)

       -rtbufsize integer (input)
           max memory used for buffering real-time frames

       -fdebug flags (input/output)
           print specific debug info

           Possible values:

           ts
       -max_delay integer (input/output)
           maximum muxing or demuxing delay in microseconds

       -fpsprobesize integer (input)
           number of frames used to probe fps

       -f_err_detect flags (input)
           set error detection flags (deprecated; use err_detect, save via avconv)

           Possible values:

           crccheck
               verify embedded CRCs

           bitstream
               detect bitstream specification deviations

           buffer
               detect improper bitstream length

           explode
               abort decoding on minor error detection

       -err_detect flags (input)
           set error detection flags

           Possible values:

           crccheck
               verify embedded CRCs

           bitstream
               detect bitstream specification deviations

           buffer
               detect improper bitstream length

           explode
               abort decoding on minor error detection

   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.

       -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. When used as an
           output option (before an output filename), decodes but discards input until the timestamps reach
           position. This is slower, but more accurate.

           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.

       -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

       -deinterlace
           Deinterlace pictures.  This option is deprecated since the deinterlacing is very low quality.  Use
           the yadif filter with "-filter:v yadif".

       -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.

   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

           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.

       -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 (output,per-stream)
           Force a tag/fourcc for matching streams.

       -cpuflags mask (global)
           Set a mask that's applied to autodetected CPU flags.  This option is intended for testing. Do not use
           it unless you know what you're doing.

       -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

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

EXPRESSION EVALUATION

       When evaluating an arithmetic expression, Libav uses an internal formula evaluator, implemented through
       the libavutil/eval.h interface.

       An expression may contain unary, binary operators, constants, and functions.

       Two expressions expr1 and expr2 can be combined to form another expression "expr1;expr2".  expr1 and
       expr2 are evaluated in turn, and the new expression evaluates to the value of expr2.

       The following binary operators are available: "+", "-", "*", "/", "^".

       The following unary operators are available: "+", "-".

       The following functions are available:

       sinh(x)
       cosh(x)
       tanh(x)
       sin(x)
       cos(x)
       tan(x)
       atan(x)
       asin(x)
       acos(x)
       exp(x)
       log(x)
       abs(x)
       squish(x)
       gauss(x)
       isinf(x)
           Return 1.0 if x is +/-INFINITY, 0.0 otherwise.

       isnan(x)
           Return 1.0 if x is NAN, 0.0 otherwise.

       mod(x, y)
       max(x, y)
       min(x, y)
       eq(x, y)
       gte(x, y)
       gt(x, y)
       lte(x, y)
       lt(x, y)
       st(var, expr)
           Allow to store the value of the expression expr in an internal variable. var specifies the number of
           the variable where to store the value, and it is a value ranging from 0 to 9. The function returns
           the value stored in the internal variable.

       ld(var)
           Allow to load the value of the internal variable with number var, which was previously stored with
           st(var, expr).  The function returns the loaded value.

       while(cond, expr)
           Evaluate expression expr while the expression cond is non-zero, and returns the value of the last
           expr evaluation, or NAN if cond was always false.

       ceil(expr)
           Round the value of expression expr upwards to the nearest integer. For example, "ceil(1.5)" is "2.0".

       floor(expr)
           Round the value of expression expr downwards to the nearest integer. For example, "floor(-1.5)" is
           "-2.0".

       trunc(expr)
           Round the value of expression expr towards zero to the nearest integer. For example, "trunc(-1.5)" is
           "-1.0".

       sqrt(expr)
           Compute the square root of expr. This is equivalent to "(expr)^.5".

       not(expr)
           Return 1.0 if expr is zero, 0.0 otherwise.

       Note that:

       "*" works like AND

       "+" works like OR

       thus

               if A then B else C

       is equivalent to

               A*B + not(A)*C

       In your C code, you can extend the list of unary and binary functions, and define recognized constants,
       so that they are available for your expressions.

       The evaluator also recognizes the International System number postfixes. If 'i' is appended after the
       postfix, powers of 2 are used instead of powers of 10. The 'B' postfix multiplies the value for 8, and
       can be appended after another postfix or used alone. This allows using for example 'KB', 'MiB', 'G' and
       'B' as postfix.

       Follows the list of available International System postfixes, with indication of the corresponding powers
       of 10 and of 2.

       y   -24 / -80

       z   -21 / -70

       a   -18 / -60

       f   -15 / -50

       p   -12 / -40

       n   -9 / -30

       u   -6 / -20

       m   -3 / -10

       c   -2

       d   -1

       h   2

       k   3 / 10

       K   3 / 10

       M   6 / 20

       G   9 / 30

       T   12 / 40

       P   15 / 40

       E   18 / 50

       Z   21 / 60

       Y   24 / 70

ENCODERS

       Encoders are configured elements in Libav which allow the encoding of multimedia streams.

       When you configure your Libav build, all the supported native encoders are enabled by default. Encoders
       requiring an external library must be enabled manually via the corresponding "--enable-lib" option. You
       can list all available encoders using the configure option "--list-encoders".

       You can disable all the encoders with the configure option "--disable-encoders" and selectively enable /
       disable single encoders with the options "--enable-encoder=ENCODER" / "--disable-encoder=ENCODER".

       The option "-codecs" of the av* tools will display the list of enabled encoders.

AUDIO ENCODERS

       A description of some of the currently available audio encoders follows.

   ac3 and ac3_fixed
       AC-3 audio encoders.

       These encoders implement part of ATSC A/52:2010 and ETSI TS 102 366, as well as the undocumented
       RealAudio 3 (a.k.a. dnet).

       The ac3 encoder uses floating-point math, while the ac3_fixed encoder only uses fixed-point integer math.
       This does not mean that one is always faster, just that one or the other may be better suited to a
       particular system. The floating-point encoder will generally produce better quality audio for a given
       bitrate. The ac3_fixed encoder is not the default codec for any of the output formats, so it must be
       specified explicitly using the option "-acodec ac3_fixed" in order to use it.

       AC-3 Metadata

       The AC-3 metadata options are used to set parameters that describe the audio, but in most cases do not
       affect the audio encoding itself. Some of the options do directly affect or influence the decoding and
       playback of the resulting bitstream, while others are just for informational purposes. A few of the
       options will add bits to the output stream that could otherwise be used for audio data, and will thus
       affect the quality of the output. Those will be indicated accordingly with a note in the option list
       below.

       These parameters are described in detail in several publicly-available documents.

       *<A/52:2010 - Digital Audio Compression (AC-3) (E-AC-3) Standard
       ("http://www.atsc.org/cms/standards/a_52-2010.pdf")>
       *<A/54 - Guide to the Use of the ATSC Digital Television Standard
       ("http://www.atsc.org/cms/standards/a_54a_with_corr_1.pdf")>
       *<Dolby Metadata Guide
       ("http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/18_Metadata.Guide.pdf")>
       *<Dolby Digital Professional Encoding Guidelines
       ("http://www.dolby.com/uploadedFiles/zz-_Shared_Assets/English_PDFs/Professional/46_DDEncodingGuidelines.pdf")>

       Metadata Control Options

       -per_frame_metadata boolean
           Allow Per-Frame Metadata. Specifies if the encoder should check for changing metadata for each frame.

           0   The metadata values set at initialization will be used for every frame in the stream. (default)

           1   Metadata values can be changed before encoding each frame.

       Downmix Levels

       -center_mixlev level
           Center Mix Level. The amount of gain the decoder should apply to the center channel when downmixing
           to stereo. This field will only be written to the bitstream if a center channel is present. The value
           is specified as a scale factor. There are 3 valid values:

           0.707
               Apply -3dB gain

           0.595
               Apply -4.5dB gain (default)

           0.500
               Apply -6dB gain

       -surround_mixlev level
           Surround Mix Level. The amount of gain the decoder should apply to the surround channel(s) when
           downmixing to stereo. This field will only be written to the bitstream if one or more surround
           channels are present. The value is specified as a scale factor.  There are 3 valid values:

           0.707
               Apply -3dB gain

           0.500
               Apply -6dB gain (default)

           0.000
               Silence Surround Channel(s)

       Audio Production Information

       Audio Production Information is optional information describing the mixing environment.  Either none or
       both of the fields are written to the bitstream.

       -mixing_level number
           Mixing Level. Specifies peak sound pressure level (SPL) in the production environment when the mix
           was mastered. Valid values are 80 to 111, or -1 for unknown or not indicated. The default value is
           -1, but that value cannot be used if the Audio Production Information is written to the bitstream.
           Therefore, if the "room_type" option is not the default value, the "mixing_level" option must not be
           -1.

       -room_type type
           Room Type. Describes the equalization used during the final mixing session at the studio or on the
           dubbing stage. A large room is a dubbing stage with the industry standard X-curve equalization; a
           small room has flat equalization.  This field will not be written to the bitstream if both the
           "mixing_level" option and the "room_type" option have the default values.

           0
           notindicated
               Not Indicated (default)

           1
           large
               Large Room

           2
           small
               Small Room

       Other Metadata Options

       -copyright boolean
           Copyright Indicator. Specifies whether a copyright exists for this audio.

           0
           off No Copyright Exists (default)

           1
           on  Copyright Exists

       -dialnorm value
           Dialogue Normalization. Indicates how far the average dialogue level of the program is below digital
           100% full scale (0 dBFS). This parameter determines a level shift during audio reproduction that sets
           the average volume of the dialogue to a preset level. The goal is to match volume level between
           program sources. A value of -31dB will result in no volume level change, relative to the source
           volume, during audio reproduction. Valid values are whole numbers in the range -31 to -1, with -31
           being the default.

       -dsur_mode mode
           Dolby Surround Mode. Specifies whether the stereo signal uses Dolby Surround (Pro Logic). This field
           will only be written to the bitstream if the audio stream is stereo. Using this option does NOT mean
           the encoder will actually apply Dolby Surround processing.

           0
           notindicated
               Not Indicated (default)

           1
           off Not Dolby Surround Encoded

           2
           on  Dolby Surround Encoded

       -original boolean
           Original Bit Stream Indicator. Specifies whether this audio is from the original source and not a
           copy.

           0
           off Not Original Source

           1
           on  Original Source (default)

       Extended Bitstream Information

       The extended bitstream options are part of the Alternate Bit Stream Syntax as specified in Annex D of the
       A/52:2010 standard. It is grouped into 2 parts.  If any one parameter in a group is specified, all values
       in that group will be written to the bitstream.  Default values are used for those that are written but
       have not been specified.  If the mixing levels are written, the decoder will use these values instead of
       the ones specified in the "center_mixlev" and "surround_mixlev" options if it supports the Alternate Bit
       Stream Syntax.

       Extended Bitstream Information - Part 1

       -dmix_mode mode
           Preferred Stereo Downmix Mode. Allows the user to select either Lt/Rt (Dolby Surround) or Lo/Ro
           (normal stereo) as the preferred stereo downmix mode.

           0
           notindicated
               Not Indicated (default)

           1
           ltrt
               Lt/Rt Downmix Preferred

           2
           loro
               Lo/Ro Downmix Preferred

       -ltrt_cmixlev level
           Lt/Rt Center Mix Level. The amount of gain the decoder should apply to the center channel when
           downmixing to stereo in Lt/Rt mode.

           1.414
               Apply +3dB gain

           1.189
               Apply +1.5dB gain

           1.000
               Apply 0dB gain

           0.841
               Apply -1.5dB gain

           0.707
               Apply -3.0dB gain

           0.595
               Apply -4.5dB gain (default)

           0.500
               Apply -6.0dB gain

           0.000
               Silence Center Channel

       -ltrt_surmixlev level
           Lt/Rt Surround Mix Level. The amount of gain the decoder should apply to the surround channel(s) when
           downmixing to stereo in Lt/Rt mode.

           0.841
               Apply -1.5dB gain

           0.707
               Apply -3.0dB gain

           0.595
               Apply -4.5dB gain

           0.500
               Apply -6.0dB gain (default)

           0.000
               Silence Surround Channel(s)

       -loro_cmixlev level
           Lo/Ro Center Mix Level. The amount of gain the decoder should apply to the center channel when
           downmixing to stereo in Lo/Ro mode.

           1.414
               Apply +3dB gain

           1.189
               Apply +1.5dB gain

           1.000
               Apply 0dB gain

           0.841
               Apply -1.5dB gain

           0.707
               Apply -3.0dB gain

           0.595
               Apply -4.5dB gain (default)

           0.500
               Apply -6.0dB gain

           0.000
               Silence Center Channel

       -loro_surmixlev level
           Lo/Ro Surround Mix Level. The amount of gain the decoder should apply to the surround channel(s) when
           downmixing to stereo in Lo/Ro mode.

           0.841
               Apply -1.5dB gain

           0.707
               Apply -3.0dB gain

           0.595
               Apply -4.5dB gain

           0.500
               Apply -6.0dB gain (default)

           0.000
               Silence Surround Channel(s)

       Extended Bitstream Information - Part 2

       -dsurex_mode mode
           Dolby Surround EX Mode. Indicates whether the stream uses Dolby Surround EX (7.1 matrixed to 5.1).
           Using this option does NOT mean the encoder will actually apply Dolby Surround EX processing.

           0
           notindicated
               Not Indicated (default)

           1
           on  Dolby Surround EX Off

           2
           off Dolby Surround EX On

       -dheadphone_mode mode
           Dolby Headphone Mode. Indicates whether the stream uses Dolby Headphone encoding (multi-channel
           matrixed to 2.0 for use with headphones). Using this option does NOT mean the encoder will actually
           apply Dolby Headphone processing.

           0
           notindicated
               Not Indicated (default)

           1
           on  Dolby Headphone Off

           2
           off Dolby Headphone On

       -ad_conv_type type
           A/D Converter Type. Indicates whether the audio has passed through HDCD A/D conversion.

           0
           standard
               Standard A/D Converter (default)

           1
           hdcd
               HDCD A/D Converter

       Other AC-3 Encoding Options

       -stereo_rematrixing boolean
           Stereo Rematrixing. Enables/Disables use of rematrixing for stereo input. This is an optional AC-3
           feature that increases quality by selectively encoding the left/right channels as mid/side. This
           option is enabled by default, and it is highly recommended that it be left as enabled except for
           testing purposes.

       Floating-Point-Only AC-3 Encoding Options

       These options are only valid for the floating-point encoder and do not exist for the fixed-point encoder
       due to the corresponding features not being implemented in fixed-point.

       -channel_coupling boolean
           Enables/Disables use of channel coupling, which is an optional AC-3 feature that increases quality by
           combining high frequency information from multiple channels into a single channel. The per-channel
           high frequency information is sent with less accuracy in both the frequency and time domains. This
           allows more bits to be used for lower frequencies while preserving enough information to reconstruct
           the high frequencies. This option is enabled by default for the floating-point encoder and should
           generally be left as enabled except for testing purposes or to increase encoding speed.

           -1
           auto
               Selected by Encoder (default)

           0
           off Disable Channel Coupling

           1
           on  Enable Channel Coupling

       -cpl_start_band number
           Coupling Start Band. Sets the channel coupling start band, from 1 to 15. If a value higher than the
           bandwidth is used, it will be reduced to 1 less than the coupling end band. If auto is used, the
           start band will be determined by the encoder based on the bit rate, sample rate, and channel layout.
           This option has no effect if channel coupling is disabled.

           -1
           auto
               Selected by Encoder (default)

DEMUXERS

       Demuxers are configured elements in Libav which allow to read the multimedia streams from a particular
       type of file.

       When you configure your Libav build, all the supported demuxers are enabled by default. You can list all
       available ones using the configure option "--list-demuxers".

       You can disable all the demuxers using the configure option "--disable-demuxers", and selectively enable
       a single demuxer with the option "--enable-demuxer=DEMUXER", or disable it with the option
       "--disable-demuxer=DEMUXER".

       The option "-formats" of the av* tools will display the list of enabled demuxers.

       The description of some of the currently available demuxers follows.

   image2
       Image file demuxer.

       This demuxer reads from a list of image files specified by a pattern.

       The pattern may contain the string "%d" or "%0Nd", which specifies the position of the characters
       representing a sequential number in each filename matched by the pattern. If the form "%d0Nd" is used,
       the string representing the number in each filename is 0-padded and N is the total number of 0-padded
       digits representing the number. The literal character '%' can be specified in the pattern with the string
       "%%".

       If the pattern contains "%d" or "%0Nd", the first filename of the file list specified by the pattern must
       contain a number inclusively contained between 0 and 4, all the following numbers must be sequential.
       This limitation may be hopefully fixed.

       The pattern may contain a suffix which is used to automatically determine the format of the images
       contained in the files.

       For example the pattern "img-%03d.bmp" will match a sequence of filenames of the form img-001.bmp,
       img-002.bmp, ..., img-010.bmp, etc.; the pattern "i%%m%%g-%d.jpg" will match a sequence of filenames of
       the form i%m%g-1.jpg, i%m%g-2.jpg, ..., i%m%g-10.jpg, etc.

       The size, the pixel format, and the format of each image must be the same for all the files in the
       sequence.

       The following example shows how to use avconv for creating a video from the images in the file sequence
       img-001.jpeg, img-002.jpeg, ..., assuming an input framerate of 10 frames per second:

               avconv -i 'img-%03d.jpeg' -r 10 out.mkv

       Note that the pattern must not necessarily contain "%d" or "%0Nd", for example to convert a single image
       file img.jpeg you can employ the command:

               avconv -i img.jpeg img.png

       -pixel_format format
           Set the pixel format (for raw image)

       -video_size   size
           Set the frame size (for raw image)

       -framerate    rate
           Set the frame rate

       -loop         bool
           Loop over the images

       -start_number start
           Specify the first number in the sequence

   applehttp
       Apple HTTP Live Streaming demuxer.

       This demuxer presents all AVStreams from all variant streams.  The id field is set to the bitrate variant
       index number. By setting the discard flags on AVStreams (by pressing 'a' or 'v' in avplay), the caller
       can decide which variant streams to actually receive.  The total bitrate of the variant that the stream
       belongs to is available in a metadata key named "variant_bitrate".

MUXERS

       Muxers are configured elements in Libav which allow writing multimedia streams to a particular type of
       file.

       When you configure your Libav build, all the supported muxers are enabled by default. You can list all
       available muxers using the configure option "--list-muxers".

       You can disable all the muxers with the configure option "--disable-muxers" and selectively enable /
       disable single muxers with the options "--enable-muxer=MUXER" / "--disable-muxer=MUXER".

       The option "-formats" of the av* tools will display the list of enabled muxers.

       A description of some of the currently available muxers follows.

   crc
       CRC (Cyclic Redundancy Check) testing format.

       This muxer computes and prints the Adler-32 CRC of all the input audio and video frames. By default audio
       frames are converted to signed 16-bit raw audio and video frames to raw video before computing the CRC.

       The output of the muxer consists of a single line of the form: CRC=0xCRC, where CRC is a hexadecimal
       number 0-padded to 8 digits containing the CRC for all the decoded input frames.

       For example to compute the CRC of the input, and store it in the file out.crc:

               avconv -i INPUT -f crc out.crc

       You can print the CRC to stdout with the command:

               avconv -i INPUT -f crc -

       You can select the output format of each frame with avconv by specifying the audio and video codec and
       format. For example to compute the CRC of the input audio converted to PCM unsigned 8-bit and the input
       video converted to MPEG-2 video, use the command:

               avconv -i INPUT -c:a pcm_u8 -c:v mpeg2video -f crc -

       See also the framecrc muxer.

   framecrc
       Per-frame CRC (Cyclic Redundancy Check) testing format.

       This muxer computes and prints the Adler-32 CRC for each decoded audio and video frame. By default audio
       frames are converted to signed 16-bit raw audio and video frames to raw video before computing the CRC.

       The output of the muxer consists of a line for each audio and video frame of the form: stream_index,
       frame_dts, frame_size, 0xCRC, where CRC is a hexadecimal number 0-padded to 8 digits containing the CRC
       of the decoded frame.

       For example to compute the CRC of each decoded frame in the input, and store it in the file out.crc:

               avconv -i INPUT -f framecrc out.crc

       You can print the CRC of each decoded frame to stdout with the command:

               avconv -i INPUT -f framecrc -

       You can select the output format of each frame with avconv by specifying the audio and video codec and
       format. For example, to compute the CRC of each decoded input audio frame converted to PCM unsigned 8-bit
       and of each decoded input video frame converted to MPEG-2 video, use the command:

               avconv -i INPUT -c:a pcm_u8 -c:v mpeg2video -f framecrc -

       See also the crc muxer.

   hls
       Apple HTTP Live Streaming muxer that segments MPEG-TS according to the HTTP Live Streaming specification.

       It creates a playlist file and numbered segment files. The output filename specifies the playlist
       filename; the segment filenames receive the same basename as the playlist, a sequential number and a .ts
       extension.

               avconv -i in.nut out.m3u8

       -hls_time seconds
           Set the segment length in seconds.

       -hls_list_size size
           Set the maximum number of playlist entries.

       -hls_wrap wrap
           Set the number after which index wraps.

       -start_number number
           Start the sequence from number.

   image2
       Image file muxer.

       The image file muxer writes video frames to image files.

       The output filenames are specified by a pattern, which can be used to produce sequentially numbered
       series of files.  The pattern may contain the string "%d" or "%0Nd", this string specifies the position
       of the characters representing a numbering in the filenames. If the form "%0Nd" is used, the string
       representing the number in each filename is 0-padded to N digits. The literal character '%' can be
       specified in the pattern with the string "%%".

       If the pattern contains "%d" or "%0Nd", the first filename of the file list specified will contain the
       number 1, all the following numbers will be sequential.

       The pattern may contain a suffix which is used to automatically determine the format of the image files
       to write.

       For example the pattern "img-%03d.bmp" will specify a sequence of filenames of the form img-001.bmp,
       img-002.bmp, ..., img-010.bmp, etc.  The pattern "img%%-%d.jpg" will specify a sequence of filenames of
       the form img%-1.jpg, img%-2.jpg, ..., img%-10.jpg, etc.

       The following example shows how to use avconv for creating a sequence of files img-001.jpeg,
       img-002.jpeg, ..., taking one image every second from the input video:

               avconv -i in.avi -vsync 1 -r 1 -f image2 'img-%03d.jpeg'

       Note that with avconv, if the format is not specified with the "-f" option and the output filename
       specifies an image file format, the image2 muxer is automatically selected, so the previous command can
       be written as:

               avconv -i in.avi -vsync 1 -r 1 'img-%03d.jpeg'

       Note also that the pattern must not necessarily contain "%d" or "%0Nd", for example to create a single
       image file img.jpeg from the input video you can employ the command:

               avconv -i in.avi -f image2 -frames:v 1 img.jpeg

       -start_number number
           Start the sequence from number.

   MOV/MP4/ISMV
       The mov/mp4/ismv muxer supports fragmentation. Normally, a MOV/MP4 file has all the metadata about all
       packets stored in one location (written at the end of the file, it can be moved to the start for better
       playback using the qt-faststart tool). A fragmented file consists of a number of fragments, where packets
       and metadata about these packets are stored together. Writing a fragmented file has the advantage that
       the file is decodable even if the writing is interrupted (while a normal MOV/MP4 is undecodable if it is
       not properly finished), and it requires less memory when writing very long files (since writing normal
       MOV/MP4 files stores info about every single packet in memory until the file is closed). The downside is
       that it is less compatible with other applications.

       Fragmentation is enabled by setting one of the AVOptions that define how to cut the file into fragments:

       -movflags frag_keyframe
           Start a new fragment at each video keyframe.

       -frag_duration duration
           Create fragments that are duration microseconds long.

       -frag_size size
           Create fragments that contain up to size bytes of payload data.

       -movflags frag_custom
           Allow the caller to manually choose when to cut fragments, by calling "av_write_frame(ctx, NULL)" to
           write a fragment with the packets written so far. (This is only useful with other applications
           integrating libavformat, not from avconv.)

       -min_frag_duration duration
           Don't create fragments that are shorter than duration microseconds long.

       If more than one condition is specified, fragments are cut when one of the specified conditions is
       fulfilled. The exception to this is "-min_frag_duration", which has to be fulfilled for any of the other
       conditions to apply.

       Additionally, the way the output file is written can be adjusted through a few other options:

       -movflags empty_moov
           Write an initial moov atom directly at the start of the file, without describing any samples in it.
           Generally, an mdat/moov pair is written at the start of the file, as a normal MOV/MP4 file,
           containing only a short portion of the file. With this option set, there is no initial mdat atom, and
           the moov atom only describes the tracks but has a zero duration.

           Files written with this option set do not work in QuickTime.  This option is implicitly set when
           writing ismv (Smooth Streaming) files.

       -movflags separate_moof
           Write a separate moof (movie fragment) atom for each track. Normally, packets for all tracks are
           written in a moof atom (which is slightly more efficient), but with this option set, the muxer writes
           one moof/mdat pair for each track, making it easier to separate tracks.

           This option is implicitly set when writing ismv (Smooth Streaming) files.

       Smooth Streaming content can be pushed in real time to a publishing point on IIS with this muxer.
       Example:

               avconv -re <<normal input/transcoding options>> -movflags isml+frag_keyframe -f ismv http://server/publishingpoint.isml/Streams(Encoder1)

   mpegts
       MPEG transport stream muxer.

       This muxer implements ISO 13818-1 and part of ETSI EN 300 468.

       The muxer options are:

       -mpegts_original_network_id number
           Set the original_network_id (default 0x0001). This is unique identifier of a network in DVB. Its main
           use is in the unique identification of a service through the path Original_Network_ID,
           Transport_Stream_ID.

       -mpegts_transport_stream_id number
           Set the transport_stream_id (default 0x0001). This identifies a transponder in DVB.

       -mpegts_service_id number
           Set the service_id (default 0x0001) also known as program in DVB.

       -mpegts_pmt_start_pid number
           Set the first PID for PMT (default 0x1000, max 0x1f00).

       -mpegts_start_pid number
           Set the first PID for data packets (default 0x0100, max 0x0f00).

       The recognized metadata settings in mpegts muxer are "service_provider" and "service_name". If they are
       not set the default for "service_provider" is "Libav" and the default for "service_name" is "Service01".

               avconv -i file.mpg -c copy \
                    -mpegts_original_network_id 0x1122 \
                    -mpegts_transport_stream_id 0x3344 \
                    -mpegts_service_id 0x5566 \
                    -mpegts_pmt_start_pid 0x1500 \
                    -mpegts_start_pid 0x150 \
                    -metadata service_provider="Some provider" \
                    -metadata service_name="Some Channel" \
                    -y out.ts

   null
       Null muxer.

       This muxer does not generate any output file, it is mainly useful for testing or benchmarking purposes.

       For example to benchmark decoding with avconv you can use the command:

               avconv -benchmark -i INPUT -f null out.null

       Note that the above command does not read or write the out.null file, but specifying the output file is
       required by the avconv syntax.

       Alternatively you can write the command as:

               avconv -benchmark -i INPUT -f null -

   matroska
       Matroska container muxer.

       This muxer implements the matroska and webm container specs.

       The recognized metadata settings in this muxer are:

       title=title name
           Name provided to a single track

       language=language name
           Specifies the language of the track in the Matroska languages form

       STEREO_MODE=mode
           Stereo 3D video layout of two views in a single video track

           mono
               video is not stereo

           left_right
               Both views are arranged side by side, Left-eye view is on the left

           bottom_top
               Both views are arranged in top-bottom orientation, Left-eye view is at bottom

           top_bottom
               Both views are arranged in top-bottom orientation, Left-eye view is on top

           checkerboard_rl
               Each view is arranged in a checkerboard interleaved pattern, Left-eye view being first

           checkerboard_lr
               Each view is arranged in a checkerboard interleaved pattern, Right-eye view being first

           row_interleaved_rl
               Each view is constituted by a row based interleaving, Right-eye view is first row

           row_interleaved_lr
               Each view is constituted by a row based interleaving, Left-eye view is first row

           col_interleaved_rl
               Both views are arranged in a column based interleaving manner, Right-eye view is first column

           col_interleaved_lr
               Both views are arranged in a column based interleaving manner, Left-eye view is first column

           anaglyph_cyan_red
               All frames are in anaglyph format viewable through red-cyan filters

           right_left
               Both views are arranged side by side, Right-eye view is on the left

           anaglyph_green_magenta
               All frames are in anaglyph format viewable through green-magenta filters

           block_lr
               Both eyes laced in one Block, Left-eye view is first

           block_rl
               Both eyes laced in one Block, Right-eye view is first

       For example a 3D WebM clip can be created using the following command line:

               avconv -i sample_left_right_clip.mpg -an -c:v libvpx -metadata STEREO_MODE=left_right -y stereo_clip.webm

   segment
       Basic stream segmenter.

       The segmenter muxer outputs streams to a number of separate files of nearly fixed duration. Output
       filename pattern can be set in a fashion similar to image2.

       Every segment starts with a video keyframe, if a video stream is present.  The segment muxer works best
       with a single constant frame rate video.

       Optionally it can generate a flat list of the created segments, one segment per line.

       segment_format format
           Override the inner container format, by default it is guessed by the filename extension.

       segment_time t
           Set segment duration to t seconds.

       segment_list name
           Generate also a listfile named name.

       segment_list_size size
           Overwrite the listfile once it reaches size entries.

       segment_wrap limit
           Wrap around segment index once it reaches limit.

               avconv -i in.mkv -c copy -map 0 -f segment -list out.list out%03d.nut

   mp3
       The MP3 muxer writes a raw MP3 stream with an ID3v2 header at the beginning and optionally an ID3v1 tag
       at the end. ID3v2.3 and ID3v2.4 are supported, the "id3v2_version" option controls which one is used. The
       legacy ID3v1 tag is not written by default, but may be enabled with the "write_id3v1" option.

       For seekable output the muxer also writes a Xing frame at the beginning, which contains the number of
       frames in the file. It is useful for computing duration of VBR files.

       The muxer supports writing ID3v2 attached pictures (APIC frames). The pictures are supplied to the muxer
       in form of a video stream with a single packet. There can be any number of those streams, each will
       correspond to a single APIC frame.  The stream metadata tags title and comment map to APIC description
       and picture type respectively. See <http://id3.org/id3v2.4.0-frames> for allowed picture types.

       Note that the APIC frames must be written at the beginning, so the muxer will buffer the audio frames
       until it gets all the pictures. It is therefore advised to provide the pictures as soon as possible to
       avoid excessive buffering.

       Examples:

       Write an mp3 with an ID3v2.3 header and an ID3v1 footer:

               avconv -i INPUT -id3v2_version 3 -write_id3v1 1 out.mp3

       Attach a picture to an mp3:

               avconv -i input.mp3 -i cover.png -c copy -metadata:s:v title="Album cover"
               -metadata:s:v comment="Cover (Front)" out.mp3

INPUT DEVICES

       Input devices are configured elements in Libav which allow to access the data coming from a multimedia
       device attached to your system.

       When you configure your Libav build, all the supported input devices are enabled by default. You can list
       all available ones using the configure option "--list-indevs".

       You can disable all the input devices using the configure option "--disable-indevs", and selectively
       enable an input device using the option "--enable-indev=INDEV", or you can disable a particular input
       device using the option "--disable-indev=INDEV".

       The option "-formats" of the av* tools will display the list of supported input devices (amongst the
       demuxers).

       A description of the currently available input devices follows.

   alsa
       ALSA (Advanced Linux Sound Architecture) input device.

       To enable this input device during configuration you need libasound installed on your system.

       This device allows capturing from an ALSA device. The name of the device to capture has to be an ALSA
       card identifier.

       An ALSA identifier has the syntax:

               hw:<CARD>[,<DEV>[,<SUBDEV>]]

       where the DEV and SUBDEV components are optional.

       The three arguments (in order: CARD,DEV,SUBDEV) specify card number or identifier, device number and
       subdevice number (-1 means any).

       To see the list of cards currently recognized by your system check the files /proc/asound/cards and
       /proc/asound/devices.

       For example to capture with avconv from an ALSA device with card id 0, you may run the command:

               avconv -f alsa -i hw:0 alsaout.wav

       For more information see: <http://www.alsa-project.org/alsa-doc/alsa-lib/pcm.html>

   bktr
       BSD video input device.

   dv1394
       Linux DV 1394 input device.

   fbdev
       Linux framebuffer input device.

       The Linux framebuffer is a graphic hardware-independent abstraction layer to show graphics on a computer
       monitor, typically on the console. It is accessed through a file device node, usually /dev/fb0.

       For more detailed information read the file Documentation/fb/framebuffer.txt included in the Linux source
       tree.

       To record from the framebuffer device /dev/fb0 with avconv:

               avconv -f fbdev -r 10 -i /dev/fb0 out.avi

       You can take a single screenshot image with the command:

               avconv -f fbdev -frames:v 1 -r 1 -i /dev/fb0 screenshot.jpeg

       See also <http://linux-fbdev.sourceforge.net/>, and fbset(1).

   jack
       JACK input device.

       To enable this input device during configuration you need libjack installed on your system.

       A JACK input device creates one or more JACK writable clients, one for each audio channel, with name
       client_name:input_N, where client_name is the name provided by the application, and N is a number which
       identifies the channel.  Each writable client will send the acquired data to the Libav input device.

       Once you have created one or more JACK readable clients, you need to connect them to one or more JACK
       writable clients.

       To connect or disconnect JACK clients you can use the jack_connect and jack_disconnect programs, or do it
       through a graphical interface, for example with qjackctl.

       To list the JACK clients and their properties you can invoke the command jack_lsp.

       Follows an example which shows how to capture a JACK readable client with avconv.

               # Create a JACK writable client with name "libav".
               $ avconv -f jack -i libav -y out.wav

               # Start the sample jack_metro readable client.
               $ jack_metro -b 120 -d 0.2 -f 4000

               # List the current JACK clients.
               $ jack_lsp -c
               system:capture_1
               system:capture_2
               system:playback_1
               system:playback_2
               libav:input_1
               metro:120_bpm

               # Connect metro to the avconv writable client.
               $ jack_connect metro:120_bpm libav:input_1

       For more information read: <http://jackaudio.org/>

   libdc1394
       IIDC1394 input device, based on libdc1394 and libraw1394.

   oss
       Open Sound System input device.

       The filename to provide to the input device is the device node representing the OSS input device, and is
       usually set to /dev/dsp.

       For example to grab from /dev/dsp using avconv use the command:

               avconv -f oss -i /dev/dsp /tmp/oss.wav

       For more information about OSS see: <http://manuals.opensound.com/usersguide/dsp.html>

   pulse
       pulseaudio input device.

       To enable this input device during configuration you need libpulse-simple installed in your system.

       The filename to provide to the input device is a source device or the string "default"

       To list the pulse source devices and their properties you can invoke the command pactl list sources.

               avconv -f pulse -i default /tmp/pulse.wav

       server AVOption

       The syntax is:

               -server <server name>

       Connects to a specific server.

       name AVOption

       The syntax is:

               -name <application name>

       Specify the application name pulse will use when showing active clients, by default it is "libav"

       stream_name AVOption

       The syntax is:

               -stream_name <stream name>

       Specify the stream name pulse will use when showing active streams, by default it is "record"

       sample_rate AVOption

       The syntax is:

               -sample_rate <samplerate>

       Specify the samplerate in Hz, by default 48kHz is used.

       channels AVOption

       The syntax is:

               -channels <N>

       Specify the channels in use, by default 2 (stereo) is set.

       frame_size AVOption

       The syntax is:

               -frame_size <bytes>

       Specify the number of byte per frame, by default it is set to 1024.

       fragment_size AVOption

       The syntax is:

               -fragment_size <bytes>

       Specify the minimal buffering fragment in pulseaudio, it will affect the audio latency. By default it is
       unset.

   sndio
       sndio input device.

       To enable this input device during configuration you need libsndio installed on your system.

       The filename to provide to the input device is the device node representing the sndio input device, and
       is usually set to /dev/audio0.

       For example to grab from /dev/audio0 using avconv use the command:

               avconv -f sndio -i /dev/audio0 /tmp/oss.wav

   video4linux2
       Video4Linux2 input video device.

       The name of the device to grab is a file device node, usually Linux systems tend to automatically create
       such nodes when the device (e.g. an USB webcam) is plugged into the system, and has a name of the kind
       /dev/videoN, where N is a number associated to the device.

       Video4Linux2 devices usually support a limited set of widthxheight sizes and framerates. You can check
       which are supported using -list_formats all for Video4Linux2 devices.

       Some usage examples of the video4linux2 devices with avconv and avplay:

               # Grab and show the input of a video4linux2 device.
               avplay -f video4linux2 -framerate 30 -video_size hd720 /dev/video0

               # Grab and record the input of a video4linux2 device, leave the
               framerate and size as previously set.
               avconv -f video4linux2 -input_format mjpeg -i /dev/video0 out.mpeg

   vfwcap
       VfW (Video for Windows) capture input device.

       The filename passed as input is the capture driver number, ranging from 0 to 9. You may use "list" as
       filename to print a list of drivers. Any other filename will be interpreted as device number 0.

   x11grab
       X11 video input device.

       This device allows to capture a region of an X11 display.

       The filename passed as input has the syntax:

               [<hostname>]:<display_number>.<screen_number>[+<x_offset>,<y_offset>]

       hostname:display_number.screen_number specifies the X11 display name of the screen to grab from. hostname
       can be omitted, and defaults to "localhost". The environment variable DISPLAY contains the default
       display name.

       x_offset and y_offset specify the offsets of the grabbed area with respect to the top-left border of the
       X11 screen. They default to 0.

       Check the X11 documentation (e.g. man X) for more detailed information.

       Use the dpyinfo program for getting basic information about the properties of your X11 display (e.g. grep
       for "name" or "dimensions").

       For example to grab from :0.0 using avconv:

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

               # Grab at position 10,20.
               avconv -f x11grab -r 25 -s cif -i :0.0+10,20 out.mpg

       follow_mouse AVOption

       The syntax is:

               -follow_mouse centered|<PIXELS>

       When it is specified with "centered", the grabbing region follows the mouse pointer and keeps the pointer
       at the center of region; otherwise, the region follows only when the mouse pointer reaches within PIXELS
       (greater than zero) to the edge of region.

       For example:

               avconv -f x11grab -follow_mouse centered -r 25 -s cif -i :0.0 out.mpg

               # Follows only when the mouse pointer reaches within 100 pixels to edge
               avconv -f x11grab -follow_mouse 100 -r 25 -s cif -i :0.0 out.mpg

       show_region AVOption

       The syntax is:

               -show_region 1

       If show_region AVOption is specified with 1, then the grabbing region will be indicated on screen. With
       this option, it's easy to know what is being grabbed if only a portion of the screen is grabbed.

       For example:

               avconv -f x11grab -show_region 1 -r 25 -s cif -i :0.0+10,20 out.mpg

               # With follow_mouse
               avconv -f x11grab -follow_mouse centered -show_region 1  -r 25 -s cif -i :0.0 out.mpg

OUTPUT DEVICES

       Output devices are configured elements in Libav which allow to write multimedia data to an output device
       attached to your system.

       When you configure your Libav build, all the supported output devices are enabled by default. You can
       list all available ones using the configure option "--list-outdevs".

       You can disable all the output devices using the configure option "--disable-outdevs", and selectively
       enable an output device using the option "--enable-outdev=OUTDEV", or you can disable a particular input
       device using the option "--disable-outdev=OUTDEV".

       The option "-formats" of the av* tools will display the list of enabled output devices (amongst the
       muxers).

       A description of the currently available output devices follows.

   alsa
       ALSA (Advanced Linux Sound Architecture) output device.

   oss
       OSS (Open Sound System) output device.

   sndio
       sndio audio output device.

PROTOCOLS

       Protocols are configured elements in Libav which allow to access resources which require the use of a
       particular protocol.

       When you configure your Libav build, all the supported protocols are enabled by default. You can list all
       available ones using the configure option "--list-protocols".

       You can disable all the protocols using the configure option "--disable-protocols", and selectively
       enable a protocol using the option "--enable-protocol=PROTOCOL", or you can disable a particular protocol
       using the option "--disable-protocol=PROTOCOL".

       The option "-protocols" of the av* tools will display the list of supported protocols.

       A description of the currently available protocols follows.

   concat
       Physical concatenation protocol.

       Allow to read and seek from many resource in sequence as if they were a unique resource.

       A URL accepted by this protocol has the syntax:

               concat:<URL1>|<URL2>|...|<URLN>

       where URL1, URL2, ..., URLN are the urls of the resource to be concatenated, each one possibly specifying
       a distinct protocol.

       For example to read a sequence of files split1.mpeg, split2.mpeg, split3.mpeg with avplay use the
       command:

               avplay concat:split1.mpeg\|split2.mpeg\|split3.mpeg

       Note that you may need to escape the character "|" which is special for many shells.

   file
       File access protocol.

       Allow to read from or read to a file.

       For example to read from a file input.mpeg with avconv use the command:

               avconv -i file:input.mpeg output.mpeg

       The av* tools default to the file protocol, that is a resource specified with the name "FILE.mpeg" is
       interpreted as the URL "file:FILE.mpeg".

   gopher
       Gopher protocol.

   hls
       Read Apple HTTP Live Streaming compliant segmented stream as a uniform one. The M3U8 playlists describing
       the segments can be remote HTTP resources or local files, accessed using the standard file protocol.  The
       nested protocol is declared by specifying "+proto" after the hls URI scheme name, where proto is either
       "file" or "http".

               hls+http://host/path/to/remote/resource.m3u8
               hls+file://path/to/local/resource.m3u8

       Using this protocol is discouraged - the hls demuxer should work just as well (if not, please report the
       issues) and is more complete.  To use the hls demuxer instead, simply use the direct URLs to the m3u8
       files.

   http
       HTTP (Hyper Text Transfer Protocol).

   mmst
       MMS (Microsoft Media Server) protocol over TCP.

   mmsh
       MMS (Microsoft Media Server) protocol over HTTP.

       The required syntax is:

               mmsh://<server>[:<port>][/<app>][/<playpath>]

   md5
       MD5 output protocol.

       Computes the MD5 hash of the data to be written, and on close writes this to the designated output or
       stdout if none is specified. It can be used to test muxers without writing an actual file.

       Some examples follow.

               # Write the MD5 hash of the encoded AVI file to the file output.avi.md5.
               avconv -i input.flv -f avi -y md5:output.avi.md5

               # Write the MD5 hash of the encoded AVI file to stdout.
               avconv -i input.flv -f avi -y md5:

       Note that some formats (typically MOV) require the output protocol to be seekable, so they will fail with
       the MD5 output protocol.

   pipe
       UNIX pipe access protocol.

       Allow to read and write from UNIX pipes.

       The accepted syntax is:

               pipe:[<number>]

       number is the number corresponding to the file descriptor of the pipe (e.g. 0 for stdin, 1 for stdout, 2
       for stderr).  If number is not specified, by default the stdout file descriptor will be used for writing,
       stdin for reading.

       For example to read from stdin with avconv:

               cat test.wav | avconv -i pipe:0
               # ...this is the same as...
               cat test.wav | avconv -i pipe:

       For writing to stdout with avconv:

               avconv -i test.wav -f avi pipe:1 | cat > test.avi
               # ...this is the same as...
               avconv -i test.wav -f avi pipe: | cat > test.avi

       Note that some formats (typically MOV), require the output protocol to be seekable, so they will fail
       with the pipe output protocol.

   rtmp
       Real-Time Messaging Protocol.

       The Real-Time Messaging Protocol (RTMP) is used for streaming multimedia content across a TCP/IP network.

       The required syntax is:

               rtmp://<server>[:<port>][/<app>][/<instance>][/<playpath>]

       The accepted parameters are:

       server
           The address of the RTMP server.

       port
           The number of the TCP port to use (by default is 1935).

       app It is the name of the application to access. It usually corresponds to the path where the application
           is installed on the RTMP server (e.g. /ondemand/, /flash/live/, etc.). You can override the value
           parsed from the URI through the "rtmp_app" option, too.

       playpath
           It is the path or name of the resource to play with reference to the application specified in app,
           may be prefixed by "mp4:". You can override the value parsed from the URI through the "rtmp_playpath"
           option, too.

       listen
           Act as a server, listening for an incoming connection.

       timeout
           Maximum time to wait for the incoming connection. Implies listen.

       Additionally, the following parameters can be set via command line options (or in code via "AVOption"s):

       rtmp_app
           Name of application to connect on the RTMP server. This option overrides the parameter specified in
           the URI.

       rtmp_buffer
           Set the client buffer time in milliseconds. The default is 3000.

       rtmp_conn
           Extra arbitrary AMF connection parameters, parsed from a string, e.g. like "B:1 S:authMe O:1
           NN:code:1.23 NS:flag:ok O:0".  Each value is prefixed by a single character denoting the type, B for
           Boolean, N for number, S for string, O for object, or Z for null, followed by a colon. For Booleans
           the data must be either 0 or 1 for FALSE or TRUE, respectively.  Likewise for Objects the data must
           be 0 or 1 to end or begin an object, respectively. Data items in subobjects may be named, by
           prefixing the type with 'N' and specifying the name before the value (i.e. "NB:myFlag:1"). This
           option may be used multiple times to construct arbitrary AMF sequences.

       rtmp_flashver
           Version of the Flash plugin used to run the SWF player. The default is LNX 9,0,124,2.

       rtmp_flush_interval
           Number of packets flushed in the same request (RTMPT only). The default is 10.

       rtmp_live
           Specify that the media is a live stream. No resuming or seeking in live streams is possible. The
           default value is "any", which means the subscriber first tries to play the live stream specified in
           the playpath. If a live stream of that name is not found, it plays the recorded stream. The other
           possible values are "live" and "recorded".

       rtmp_pageurl
           URL of the web page in which the media was embedded. By default no value will be sent.

       rtmp_playpath
           Stream identifier to play or to publish. This option overrides the parameter specified in the URI.

       rtmp_subscribe
           Name of live stream to subscribe to. By default no value will be sent.  It is only sent if the option
           is specified or if rtmp_live is set to live.

       rtmp_swfhash
           SHA256 hash of the decompressed SWF file (32 bytes).

       rtmp_swfsize
           Size of the decompressed SWF file, required for SWFVerification.

       rtmp_swfurl
           URL of the SWF player for the media. By default no value will be sent.

       rtmp_swfverify
           URL to player swf file, compute hash/size automatically.

       rtmp_tcurl
           URL of the target stream. Defaults to proto://host[:port]/app.

       For example to read with avplay a multimedia resource named "sample" from the application "vod" from an
       RTMP server "myserver":

               avplay rtmp://myserver/vod/sample

   rtmpe
       Encrypted Real-Time Messaging Protocol.

       The Encrypted Real-Time Messaging Protocol (RTMPE) is used for streaming multimedia content within
       standard cryptographic primitives, consisting of Diffie-Hellman key exchange and HMACSHA256, generating a
       pair of RC4 keys.

   rtmps
       Real-Time Messaging Protocol over a secure SSL connection.

       The Real-Time Messaging Protocol (RTMPS) is used for streaming multimedia content across an encrypted
       connection.

   rtmpt
       Real-Time Messaging Protocol tunneled through HTTP.

       The Real-Time Messaging Protocol tunneled through HTTP (RTMPT) is used for streaming multimedia content
       within HTTP requests to traverse firewalls.

   rtmpte
       Encrypted Real-Time Messaging Protocol tunneled through HTTP.

       The Encrypted Real-Time Messaging Protocol tunneled through HTTP (RTMPTE) is used for streaming
       multimedia content within HTTP requests to traverse firewalls.

   rtmpts
       Real-Time Messaging Protocol tunneled through HTTPS.

       The Real-Time Messaging Protocol tunneled through HTTPS (RTMPTS) is used for streaming multimedia content
       within HTTPS requests to traverse firewalls.

   rtmp, rtmpe, rtmps, rtmpt, rtmpte
       Real-Time Messaging Protocol and its variants supported through librtmp.

       Requires the presence of the librtmp headers and library during configuration. You need to explicitly
       configure the build with "--enable-librtmp". If enabled this will replace the native RTMP protocol.

       This protocol provides most client functions and a few server functions needed to support RTMP, RTMP
       tunneled in HTTP (RTMPT), encrypted RTMP (RTMPE), RTMP over SSL/TLS (RTMPS) and tunneled variants of
       these encrypted types (RTMPTE, RTMPTS).

       The required syntax is:

               <rtmp_proto>://<server>[:<port>][/<app>][/<playpath>] <options>

       where rtmp_proto is one of the strings "rtmp", "rtmpt", "rtmpe", "rtmps", "rtmpte", "rtmpts"
       corresponding to each RTMP variant, and server, port, app and playpath have the same meaning as specified
       for the RTMP native protocol.  options contains a list of space-separated options of the form key=val.

       See the librtmp manual page (man 3 librtmp) for more information.

       For example, to stream a file in real-time to an RTMP server using avconv:

               avconv -re -i myfile -f flv rtmp://myserver/live/mystream

       To play the same stream using avplay:

               avplay "rtmp://myserver/live/mystream live=1"

   rtp
       Real-Time Protocol.

   rtsp
       RTSP is not technically a protocol handler in libavformat, it is a demuxer and muxer. The demuxer
       supports both normal RTSP (with data transferred over RTP; this is used by e.g. Apple and Microsoft) and
       Real-RTSP (with data transferred over RDT).

       The muxer can be used to send a stream using RTSP ANNOUNCE to a server supporting it (currently Darwin
       Streaming Server and Mischa Spiegelmock's
        RTSP server ("http://github.com/revmischa/rtsp-server")).

       The required syntax for a RTSP url is:

               rtsp://<hostname>[:<port>]/<path>

       The following options (set on the avconv/avplay command line, or set in code via "AVOption"s or in
       "avformat_open_input"), are supported:

       Flags for "rtsp_transport":

       udp Use UDP as lower transport protocol.

       tcp Use TCP (interleaving within the RTSP control channel) as lower transport protocol.

       udp_multicast
           Use UDP multicast as lower transport protocol.

       http
           Use HTTP tunneling as lower transport protocol, which is useful for passing proxies.

       Multiple lower transport protocols may be specified, in that case they are tried one at a time (if the
       setup of one fails, the next one is tried).  For the muxer, only the "tcp" and "udp" options are
       supported.

       Flags for "rtsp_flags":

       filter_src
           Accept packets only from negotiated peer address and port.

       listen
           Act as a server, listening for an incoming connection.

       When receiving data over UDP, the demuxer tries to reorder received packets (since they may arrive out of
       order, or packets may get lost totally). This can be disabled by setting the maximum demuxing delay to
       zero (via the "max_delay" field of AVFormatContext).

       When watching multi-bitrate Real-RTSP streams with avplay, the streams to display can be chosen with
       "-vst" n and "-ast" n for video and audio respectively, and can be switched on the fly by pressing "v"
       and "a".

       Example command lines:

       To watch a stream over UDP, with a max reordering delay of 0.5 seconds:

               avplay -max_delay 500000 -rtsp_transport udp rtsp://server/video.mp4

       To watch a stream tunneled over HTTP:

               avplay -rtsp_transport http rtsp://server/video.mp4

       To send a stream in realtime to a RTSP server, for others to watch:

               avconv -re -i <input> -f rtsp -muxdelay 0.1 rtsp://server/live.sdp

       To receive a stream in realtime:

               avconv -rtsp_flags listen -i rtsp://ownaddress/live.sdp <output>

   sap
       Session Announcement Protocol (RFC 2974). This is not technically a protocol handler in libavformat, it
       is a muxer and demuxer.  It is used for signalling of RTP streams, by announcing the SDP for the streams
       regularly on a separate port.

       Muxer

       The syntax for a SAP url given to the muxer is:

               sap://<destination>[:<port>][?<options>]

       The RTP packets are sent to destination on port port, or to port 5004 if no port is specified.  options
       is a "&"-separated list. The following options are supported:

       announce_addr=address
           Specify the destination IP address for sending the announcements to.  If omitted, the announcements
           are sent to the commonly used SAP announcement multicast address 224.2.127.254 (sap.mcast.net), or
           ff0e::2:7ffe if destination is an IPv6 address.

       announce_port=port
           Specify the port to send the announcements on, defaults to 9875 if not specified.

       ttl=ttl
           Specify the time to live value for the announcements and RTP packets, defaults to 255.

       same_port=0|1
           If set to 1, send all RTP streams on the same port pair. If zero (the default), all streams are sent
           on unique ports, with each stream on a port 2 numbers higher than the previous.  VLC/Live555 requires
           this to be set to 1, to be able to receive the stream.  The RTP stack in libavformat for receiving
           requires all streams to be sent on unique ports.

       Example command lines follow.

       To broadcast a stream on the local subnet, for watching in VLC:

               avconv -re -i <input> -f sap sap://224.0.0.255?same_port=1

       Similarly, for watching in avplay:

               avconv -re -i <input> -f sap sap://224.0.0.255

       And for watching in avplay, over IPv6:

               avconv -re -i <input> -f sap sap://[ff0e::1:2:3:4]

       Demuxer

       The syntax for a SAP url given to the demuxer is:

               sap://[<address>][:<port>]

       address is the multicast address to listen for announcements on, if omitted, the default 224.2.127.254
       (sap.mcast.net) is used. port is the port that is listened on, 9875 if omitted.

       The demuxers listens for announcements on the given address and port.  Once an announcement is received,
       it tries to receive that particular stream.

       Example command lines follow.

       To play back the first stream announced on the normal SAP multicast address:

               avplay sap://

       To play back the first stream announced on one the default IPv6 SAP multicast address:

               avplay sap://[ff0e::2:7ffe]

   tcp
       Trasmission Control Protocol.

       The required syntax for a TCP url is:

               tcp://<hostname>:<port>[?<options>]

       listen
           Listen for an incoming connection

                   avconv -i <input> -f <format> tcp://<hostname>:<port>?listen
                   avplay tcp://<hostname>:<port>

   udp
       User Datagram Protocol.

       The required syntax for a UDP url is:

               udp://<hostname>:<port>[?<options>]

       options contains a list of &-seperated options of the form key=val.  Follow the list of supported
       options.

       buffer_size=size
           set the UDP buffer size in bytes

       localport=port
           override the local UDP port to bind with

       localaddr=addr
           Choose the local IP address. This is useful e.g. if sending multicast and the host has multiple
           interfaces, where the user can choose which interface to send on by specifying the IP address of that
           interface.

       pkt_size=size
           set the size in bytes of UDP packets

       reuse=1|0
           explicitly allow or disallow reusing UDP sockets

       ttl=ttl
           set the time to live value (for multicast only)

       connect=1|0
           Initialize the UDP socket with "connect()". In this case, the destination address can't be changed
           with ff_udp_set_remote_url later.  If the destination address isn't known at the start, this option
           can be specified in ff_udp_set_remote_url, too.  This allows finding out the source address for the
           packets with getsockname, and makes writes return with AVERROR(ECONNREFUSED) if "destination
           unreachable" is received.  For receiving, this gives the benefit of only receiving packets from the
           specified peer address/port.

       sources=address[,address]
           Only receive packets sent to the multicast group from one of the specified sender IP addresses.

       block=address[,address]
           Ignore packets sent to the multicast group from the specified sender IP addresses.

       Some usage examples of the udp protocol with avconv follow.

       To stream over UDP to a remote endpoint:

               avconv -i <input> -f <format> udp://<hostname>:<port>

       To stream in mpegts format over UDP using 188 sized UDP packets, using a large input buffer:

               avconv -i <input> -f mpegts udp://<hostname>:<port>?pkt_size=188&buffer_size=65535

       To receive over UDP from a remote endpoint:

               avconv -i udp://[<multicast-address>]:<port>

BITSTREAM FILTERS

       When you configure your Libav build, all the supported bitstream filters are enabled by default. You can
       list all available ones using the configure option "--list-bsfs".

       You can disable all the bitstream filters using the configure option "--disable-bsfs", and selectively
       enable any bitstream filter using the option "--enable-bsf=BSF", or you can disable a particular
       bitstream filter using the option "--disable-bsf=BSF".

       The option "-bsfs" of the av* tools will display the list of all the supported bitstream filters included
       in your build.

       Below is a description of the currently available bitstream filters.

   aac_adtstoasc
   chomp
   dump_extradata
   h264_mp4toannexb
   imx_dump_header
   mjpeg2jpeg
       Convert MJPEG/AVI1 packets to full JPEG/JFIF packets.

       MJPEG is a video codec wherein each video frame is essentially a JPEG image. The individual frames can be
       extracted without loss, e.g. by

               avconv -i ../some_mjpeg.avi -c:v copy frames_%d.jpg

       Unfortunately, these chunks are incomplete JPEG images, because they lack the DHT segment required for
       decoding. Quoting from <http://www.digitalpreservation.gov/formats/fdd/fdd000063.shtml>:

       Avery Lee, writing in the rec.video.desktop newsgroup in 2001, commented that "MJPEG, or at least the
       MJPEG in AVIs having the MJPG fourcc, is restricted JPEG with a fixed -- and *omitted* -- Huffman table.
       The JPEG must be YCbCr colorspace, it must be 4:2:2, and it must use basic Huffman encoding, not
       arithmetic or progressive. . . . You can indeed extract the MJPEG frames and decode them with a regular
       JPEG decoder, but you have to prepend the DHT segment to them, or else the decoder won't have any idea
       how to decompress the data. The exact table necessary is given in the OpenDML spec."

       This bitstream filter patches the header of frames extracted from an MJPEG stream (carrying the AVI1
       header ID and lacking a DHT segment) to produce fully qualified JPEG images.

               avconv -i mjpeg-movie.avi -c:v copy -bsf:v mjpeg2jpeg frame_%d.jpg
               exiftran -i -9 frame*.jpg
               avconv -i frame_%d.jpg -c:v copy rotated.avi

   mjpega_dump_header
   movsub
   mp3_header_compress
   mp3_header_decompress
   noise
   remove_extradata

FILTERGRAPH DESCRIPTION

       A filtergraph is a directed graph of connected filters. It can contain cycles, and there can be multiple
       links between a pair of filters. Each link has one input pad on one side connecting it to one filter from
       which it takes its input, and one output pad on the other side connecting it to the one filter accepting
       its output.

       Each filter in a filtergraph is an instance of a filter class registered in the application, which
       defines the features and the number of input and output pads of the filter.

       A filter with no input pads is called a "source", a filter with no output pads is called a "sink".

   Filtergraph syntax
       A filtergraph can be represented using a textual representation, which is recognized by the -filter/-vf
       and -filter_complex options in avconv and -vf in avplay, and by the
       "avfilter_graph_parse()"/"avfilter_graph_parse2()" function defined in libavfilter/avfiltergraph.h.

       A filterchain consists of a sequence of connected filters, each one connected to the previous one in the
       sequence. A filterchain is represented by a list of ","-separated filter descriptions.

       A filtergraph consists of a sequence of filterchains. A sequence of filterchains is represented by a list
       of ";"-separated filterchain descriptions.

       A filter is represented by a string of the form:
       [in_link_1]...[in_link_N]filter_name=arguments[out_link_1]...[out_link_M]

       filter_name is the name of the filter class of which the described filter is an instance of, and has to
       be the name of one of the filter classes registered in the program.  The name of the filter class is
       optionally followed by a string "=arguments".

       arguments is a string which contains the parameters used to initialize the filter instance, and are
       described in the filter descriptions below.

       The list of arguments can be quoted using the character "'" as initial and ending mark, and the character
       '\' for escaping the characters within the quoted text; otherwise the argument string is considered
       terminated when the next special character (belonging to the set "[]=;,") is encountered.

       The name and arguments of the filter are optionally preceded and followed by a list of link labels.  A
       link label allows to name a link and associate it to a filter output or input pad. The preceding labels
       in_link_1 ... in_link_N, are associated to the filter input pads, the following labels out_link_1 ...
       out_link_M, are associated to the output pads.

       When two link labels with the same name are found in the filtergraph, a link between the corresponding
       input and output pad is created.

       If an output pad is not labelled, it is linked by default to the first unlabelled input pad of the next
       filter in the filterchain.  For example in the filterchain:

               nullsrc, split[L1], [L2]overlay, nullsink

       the split filter instance has two output pads, and the overlay filter instance two input pads. The first
       output pad of split is labelled "L1", the first input pad of overlay is labelled "L2", and the second
       output pad of split is linked to the second input pad of overlay, which are both unlabelled.

       In a complete filterchain all the unlabelled filter input and output pads must be connected. A
       filtergraph is considered valid if all the filter input and output pads of all the filterchains are
       connected.

       Libavfilter will automatically insert scale filters where format conversion is required. It is possible
       to specify swscale flags for those automatically inserted scalers by prepending "sws_flags=flags;" to the
       filtergraph description.

       Follows a BNF description for the filtergraph syntax:

               <NAME>             ::= sequence of alphanumeric characters and '_'
               <LINKLABEL>        ::= "[" <NAME> "]"
               <LINKLABELS>       ::= <LINKLABEL> [<LINKLABELS>]
               <FILTER_ARGUMENTS> ::= sequence of chars (eventually quoted)
               <FILTER>           ::= [<LINKLABELS>] <NAME> ["=" <FILTER_ARGUMENTS>] [<LINKLABELS>]
               <FILTERCHAIN>      ::= <FILTER> [,<FILTERCHAIN>]
               <FILTERGRAPH>      ::= [sws_flags=<flags>;] <FILTERCHAIN> [;<FILTERGRAPH>]

AUDIO FILTERS

       When you configure your Libav build, you can disable any of the existing filters using --disable-filters.
       The configure output will show the audio filters included in your build.

       Below is a description of the currently available audio filters.

   aformat
       Convert the input audio to one of the specified formats. The framework will negotiate the most
       appropriate format to minimize conversions.

       The filter accepts the following named parameters:

       sample_fmts
           A comma-separated list of requested sample formats.

       sample_rates
           A comma-separated list of requested sample rates.

       channel_layouts
           A comma-separated list of requested channel layouts.

       If a parameter is omitted, all values are allowed.

       For example to force the output to either unsigned 8-bit or signed 16-bit stereo:

               aformat=sample_fmts\=u8,s16:channel_layouts\=stereo

   amix
       Mixes multiple audio inputs into a single output.

       For example

               avconv -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex amix=inputs=3:duration=first:dropout_transition=3 OUTPUT

       will mix 3 input audio streams to a single output with the same duration as the first input and a dropout
       transition time of 3 seconds.

       The filter accepts the following named parameters:

       inputs
           Number of inputs. If unspecified, it defaults to 2.

       duration
           How to determine the end-of-stream.

           longest
               Duration of longest input. (default)

           shortest
               Duration of shortest input.

           first
               Duration of first input.

       dropout_transition
           Transition time, in seconds, for volume renormalization when an input stream ends. The default value
           is 2 seconds.

   anull
       Pass the audio source unchanged to the output.

   ashowinfo
       Show a line containing various information for each input audio frame.  The input audio is not modified.

       The shown line contains a sequence of key/value pairs of the form key:value.

       A description of each shown parameter follows:

       n   sequential number of the input frame, starting from 0

       pts Presentation timestamp of the input frame, in time base units; the time base depends on the filter
           input pad, and is usually 1/sample_rate.

       pts_time
           presentation timestamp of the input frame in seconds

       fmt sample format

       chlayout
           channel layout

       rate
           sample rate for the audio frame

       nb_samples
           number of samples (per channel) in the frame

       checksum
           Adler-32 checksum (printed in hexadecimal) of the audio data. For planar audio the data is treated as
           if all the planes were concatenated.

       plane_checksums
           A list of Adler-32 checksums for each data plane.

   asplit
       Split input audio into several identical outputs.

       The filter accepts a single parameter which specifies the number of outputs. If unspecified, it defaults
       to 2.

       For example

               avconv -i INPUT -filter_complex asplit=5 OUTPUT

       will create 5 copies of the input audio.

   asyncts
       Synchronize audio data with timestamps by squeezing/stretching it and/or dropping samples/adding silence
       when needed.

       The filter accepts the following named parameters:

       compensate
           Enable stretching/squeezing the data to make it match the timestamps. Disabled by default. When
           disabled, time gaps are covered with silence.

       min_delta
           Minimum difference between timestamps and audio data (in seconds) to trigger adding/dropping samples.
           Default value is 0.1. If you get non-perfect sync with this filter, try setting this parameter to 0.

       max_comp
           Maximum compensation in samples per second. Relevant only with compensate=1.  Default value 500.

       first_pts
           Assume the first pts should be this value. The time base is 1 / sample rate.  This allows for
           padding/trimming at the start of stream. By default, no assumption is made about the first frame's
           expected pts, so no padding or trimming is done. For example, this could be set to 0 to pad the
           beginning with silence if an audio stream starts after the video stream or to trim any samples with a
           negative pts due to encoder delay.

   channelsplit
       Split each channel in input audio stream into a separate output stream.

       This filter accepts the following named parameters:

       channel_layout
           Channel layout of the input stream. Default is "stereo".

       For example, assuming a stereo input MP3 file

               avconv -i in.mp3 -filter_complex channelsplit out.mkv

       will create an output Matroska file with two audio streams, one containing only the left channel and the
       other the right channel.

       To split a 5.1 WAV file into per-channel files

               avconv -i in.wav -filter_complex
               'channelsplit=channel_layout=5.1[FL][FR][FC][LFE][SL][SR]'
               -map '[FL]' front_left.wav -map '[FR]' front_right.wav -map '[FC]'
               front_center.wav -map '[LFE]' lfe.wav -map '[SL]' side_left.wav -map '[SR]'
               side_right.wav

   channelmap
       Remap input channels to new locations.

       This filter accepts the following named parameters:

       channel_layout
           Channel layout of the output stream.

       map Map channels from input to output. The argument is a comma-separated list of mappings, each in the
           "in_channel-out_channel" or in_channel form. in_channel can be either the name of the input channel
           (e.g. FL for front left) or its index in the input channel layout.  out_channel is the name of the
           output channel or its index in the output channel layout. If out_channel is not given then it is
           implicitly an index, starting with zero and increasing by one for each mapping.

       If no mapping is present, the filter will implicitly map input channels to output channels preserving
       index.

       For example, assuming a 5.1+downmix input MOV file

               avconv -i in.mov -filter 'channelmap=map=DL-FL,DR-FR' out.wav

       will create an output WAV file tagged as stereo from the downmix channels of the input.

       To fix a 5.1 WAV improperly encoded in AAC's native channel order

               avconv -i in.wav -filter 'channelmap=1,2,0,5,3,4:channel_layout=5.1' out.wav

   join
       Join multiple input streams into one multi-channel stream.

       The filter accepts the following named parameters:

       inputs
           Number of input streams. Defaults to 2.

       channel_layout
           Desired output channel layout. Defaults to stereo.

       map Map channels from inputs to output. The argument is a comma-separated list of mappings, each in the
           "input_idx.in_channel-out_channel" form. input_idx is the 0-based index of the input stream.
           in_channel can be either the name of the input channel (e.g. FL for front left) or its index in the
           specified input stream. out_channel is the name of the output channel.

       The filter will attempt to guess the mappings when those are not specified explicitly. It does so by
       first trying to find an unused matching input channel and if that fails it picks the first unused input
       channel.

       E.g. to join 3 inputs (with properly set channel layouts)

               avconv -i INPUT1 -i INPUT2 -i INPUT3 -filter_complex join=inputs=3 OUTPUT

       To build a 5.1 output from 6 single-channel streams:

               avconv -i fl -i fr -i fc -i sl -i sr -i lfe -filter_complex
               'join=inputs=6:channel_layout=5.1:map=0.0-FL,1.0-FR,2.0-FC,3.0-SL,4.0-SR,5.0-LFE'
               out

   resample
       Convert the audio sample format, sample rate and channel layout. This filter is not meant to be used
       directly, it is inserted automatically by libavfilter whenever conversion is needed. Use the aformat
       filter to force a specific conversion.

   volume
       Adjust the input audio volume.

       The filter accepts the following named parameters:

       volume
           Expresses how the audio volume will be increased or decreased.

           Output values are clipped to the maximum value.

           The output audio volume is given by the relation:

                   <output_volume> = <volume> * <input_volume>

           Default value for volume is 1.0.

       precision
           Mathematical precision.

           This determines which input sample formats will be allowed, which affects the precision of the volume
           scaling.

           fixed
               8-bit fixed-point; limits input sample format to U8, S16, and S32.

           float
               32-bit floating-point; limits input sample format to FLT. (default)

           double
               64-bit floating-point; limits input sample format to DBL.

       Examples

       •   Halve the input audio volume:

                   volume=volume=0.5
                   volume=volume=1/2
                   volume=volume=-6.0206dB

       •   Increase input audio power by 6 decibels using fixed-point precision:

                   volume=volume=6dB:precision=fixed

AUDIO SOURCES

       Below is a description of the currently available audio sources.

   anullsrc
       Null audio source, never return audio frames. It is mainly useful as a template and to be employed in
       analysis / debugging tools.

       It accepts as optional parameter a string of the form sample_rate:channel_layout.

       sample_rate specify the sample rate, and defaults to 44100.

       channel_layout specify the channel layout, and can be either an integer or a string representing a
       channel layout. The default value of channel_layout is 3, which corresponds to CH_LAYOUT_STEREO.

       Check the channel_layout_map definition in libavutil/channel_layout.c for the mapping between strings and
       channel layout values.

       Follow some examples:

               #  set the sample rate to 48000 Hz and the channel layout to CH_LAYOUT_MONO.
               anullsrc=48000:4

               # same as
               anullsrc=48000:mono

   abuffer
       Buffer audio frames, and make them available to the filter chain.

       This source is not intended to be part of user-supplied graph descriptions but for insertion by calling
       programs through the interface defined in libavfilter/buffersrc.h.

       It accepts the following named parameters:

       time_base
           Timebase which will be used for timestamps of submitted frames. It must be either a floating-point
           number or in numerator/denominator form.

       sample_rate
           Audio sample rate.

       sample_fmt
           Name of the sample format, as returned by "av_get_sample_fmt_name()".

       channel_layout
           Channel layout of the audio data, in the form that can be accepted by "av_get_channel_layout()".

       All the parameters need to be explicitly defined.

AUDIO SINKS

       Below is a description of the currently available audio sinks.

   anullsink
       Null audio sink, do absolutely nothing with the input audio. It is mainly useful as a template and to be
       employed in analysis / debugging tools.

   abuffersink
       This sink is intended for programmatic use. Frames that arrive on this sink can be retrieved by the
       calling program using the interface defined in libavfilter/buffersink.h.

       This filter accepts no parameters.

VIDEO FILTERS

       When you configure your Libav build, you can disable any of the existing filters using --disable-filters.
       The configure output will show the video filters included in your build.

       Below is a description of the currently available video filters.

   blackframe
       Detect frames that are (almost) completely black. Can be useful to detect chapter transitions or
       commercials. Output lines consist of the frame number of the detected frame, the percentage of blackness,
       the position in the file if known or -1 and the timestamp in seconds.

       In order to display the output lines, you need to set the loglevel at least to the AV_LOG_INFO value.

       The filter accepts the syntax:

               blackframe[=<amount>:[<threshold>]]

       amount is the percentage of the pixels that have to be below the threshold, and defaults to 98.

       threshold is the threshold below which a pixel value is considered black, and defaults to 32.

   boxblur
       Apply boxblur algorithm to the input video.

       This filter accepts the parameters:
       luma_power:luma_radius:chroma_radius:chroma_power:alpha_radius:alpha_power

       Chroma and alpha parameters are optional, if not specified they default to the corresponding values set
       for luma_radius and luma_power.

       luma_radius, chroma_radius, and alpha_radius represent the radius in pixels of the box used for blurring
       the corresponding input plane. They are expressions, and can contain the following constants:

       w, h
           the input width and height in pixels

       cw, ch
           the input chroma image width and height in pixels

       hsub, vsub
           horizontal and vertical chroma subsample values. For example for the pixel format "yuv422p" hsub is 2
           and vsub is 1.

       The radius must be a non-negative number, and must not be greater than the value of the expression
       "min(w,h)/2" for the luma and alpha planes, and of "min(cw,ch)/2" for the chroma planes.

       luma_power, chroma_power, and alpha_power represent how many times the boxblur filter is applied to the
       corresponding plane.

       Some examples follow:

       •   Apply a boxblur filter with luma, chroma, and alpha radius set to 2:

                   boxblur=2:1

       •   Set luma radius to 2, alpha and chroma radius to 0

                   boxblur=2:1:0:0:0:0

       •   Set luma and chroma radius to a fraction of the video dimension

                   boxblur=min(h,w)/10:1:min(cw,ch)/10:1

   copy
       Copy the input source unchanged to the output. Mainly useful for testing purposes.

   crop
       Crop the input video to out_w:out_h:x:y.

       The parameters are expressions containing the following constants:

       E, PI, PHI
           the corresponding mathematical approximated values for e (euler number), pi (greek PI), PHI (golden
           ratio)

       x, y
           the computed values for x and y. They are evaluated for each new frame.

       in_w, in_h
           the input width and height

       iw, ih
           same as in_w and in_h

       out_w, out_h
           the output (cropped) width and height

       ow, oh
           same as out_w and out_h

       n   the number of input frame, starting from 0

       pos the position in the file of the input frame, NAN if unknown

       t   timestamp expressed in seconds, NAN if the input timestamp is unknown

       The out_w and out_h parameters specify the expressions for the width and height of the output (cropped)
       video. They are evaluated just at the configuration of the filter.

       The default value of out_w is "in_w", and the default value of out_h is "in_h".

       The expression for out_w may depend on the value of out_h, and the expression for out_h may depend on
       out_w, but they cannot depend on x and y, as x and y are evaluated after out_w and out_h.

       The x and y parameters specify the expressions for the position of the top-left corner of the output
       (non-cropped) area. They are evaluated for each frame. If the evaluated value is not valid, it is
       approximated to the nearest valid value.

       The default value of x is "(in_w-out_w)/2", and the default value for y is "(in_h-out_h)/2", which set
       the cropped area at the center of the input image.

       The expression for x may depend on y, and the expression for y may depend on x.

       Follow some examples:

               # crop the central input area with size 100x100
               crop=100:100

               # crop the central input area with size 2/3 of the input video
               "crop=2/3*in_w:2/3*in_h"

               # crop the input video central square
               crop=in_h

               # delimit the rectangle with the top-left corner placed at position
               # 100:100 and the right-bottom corner corresponding to the right-bottom
               # corner of the input image.
               crop=in_w-100:in_h-100:100:100

               # crop 10 pixels from the left and right borders, and 20 pixels from
               # the top and bottom borders
               "crop=in_w-2*10:in_h-2*20"

               # keep only the bottom right quarter of the input image
               "crop=in_w/2:in_h/2:in_w/2:in_h/2"

               # crop height for getting Greek harmony
               "crop=in_w:1/PHI*in_w"

               # trembling effect
               "crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(n/10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(n/7)"

               # erratic camera effect depending on timestamp
               "crop=in_w/2:in_h/2:(in_w-out_w)/2+((in_w-out_w)/2)*sin(t*10):(in_h-out_h)/2 +((in_h-out_h)/2)*sin(t*13)"

               # set x depending on the value of y
               "crop=in_w/2:in_h/2:y:10+10*sin(n/10)"

   cropdetect
       Auto-detect crop size.

       Calculate necessary cropping parameters and prints the recommended parameters through the logging system.
       The detected dimensions correspond to the non-black area of the input video.

       It accepts the syntax:

               cropdetect[=<limit>[:<round>[:<reset>]]]

       limit
           Threshold, which can be optionally specified from nothing (0) to everything (255), defaults to 24.

       round
           Value which the width/height should be divisible by, defaults to 16. The offset is automatically
           adjusted to center the video. Use 2 to get only even dimensions (needed for 4:2:2 video). 16 is best
           when encoding to most video codecs.

       reset
           Counter that determines after how many frames cropdetect will reset the previously detected largest
           video area and start over to detect the current optimal crop area. Defaults to 0.

           This can be useful when channel logos distort the video area. 0 indicates never reset and return the
           largest area encountered during playback.

   delogo
       Suppress a TV station logo by a simple interpolation of the surrounding pixels. Just set a rectangle
       covering the logo and watch it disappear (and sometimes something even uglier appear - your mileage may
       vary).

       The filter accepts parameters as a string of the form "x:y:w:h:band", or as a list of key=value pairs,
       separated by ":".

       The description of the accepted parameters follows.

       x, y
           Specify the top left corner coordinates of the logo. They must be specified.

       w, h
           Specify the width and height of the logo to clear. They must be specified.

       band, t
           Specify the thickness of the fuzzy edge of the rectangle (added to w and h). The default value is 4.

       show
           When set to 1, a green rectangle is drawn on the screen to simplify finding the right x, y, w, h
           parameters, and band is set to 4. The default value is 0.

       Some examples follow.

       •   Set a rectangle covering the area with top left corner coordinates 0,0 and size 100x77, setting a
           band of size 10:

                   delogo=0:0:100:77:10

       •   As the previous example, but use named options:

                   delogo=x=0:y=0:w=100:h=77:band=10

   drawbox
       Draw a colored box on the input image.

       It accepts the syntax:

               drawbox=<x>:<y>:<width>:<height>:<color>

       x, y
           Specify the top left corner coordinates of the box. Default to 0.

       width, height
           Specify the width and height of the box, if 0 they are interpreted as the input width and height.
           Default to 0.

       color
           Specify the color of the box to write, it can be the name of a color (case insensitive match) or a
           0xRRGGBB[AA] sequence.

       Follow some examples:

               # draw a black box around the edge of the input image
               drawbox

               # draw a box with color red and an opacity of 50%
               drawbox=10:20:200:60:red@0.5"

   drawtext
       Draw text string or text from specified file on top of video using the libfreetype library.

       To enable compilation of this filter you need to configure Libav with "--enable-libfreetype".

       The filter also recognizes strftime() sequences in the provided text and expands them accordingly. Check
       the documentation of strftime().

       The filter accepts parameters as a list of key=value pairs, separated by ":".

       The description of the accepted parameters follows.

       fontfile
           The font file to be used for drawing text. Path must be included.  This parameter is mandatory.

       text
           The text string to be drawn. The text must be a sequence of UTF-8 encoded characters.  This parameter
           is mandatory if no file is specified with the parameter textfile.

       textfile
           A text file containing text to be drawn. The text must be a sequence of UTF-8 encoded characters.

           This parameter is mandatory if no text string is specified with the parameter text.

           If both text and textfile are specified, an error is thrown.

       x, y
           The offsets where text will be drawn within the video frame.  Relative to the top/left border of the
           output image.  They accept expressions similar to the overlay filter:

           x, y
               the computed values for x and y. They are evaluated for each new frame.

           main_w, main_h
               main input width and height

           W, H
               same as main_w and main_h

           text_w, text_h
               rendered text width and height

           w, h
               same as text_w and text_h

           n   the number of frames processed, starting from 0

           t   timestamp expressed in seconds, NAN if the input timestamp is unknown

           The default value of x and y is 0.

       fontsize
           The font size to be used for drawing text.  The default value of fontsize is 16.

       fontcolor
           The color to be used for drawing fonts.  Either a string (e.g. "red") or in 0xRRGGBB[AA] format (e.g.
           "0xff000033"), possibly followed by an alpha specifier.  The default value of fontcolor is "black".

       boxcolor
           The color to be used for drawing box around text.  Either a string (e.g. "yellow") or in 0xRRGGBB[AA]
           format (e.g. "0xff00ff"), possibly followed by an alpha specifier.  The default value of boxcolor is
           "white".

       box Used to draw a box around text using background color.  Value should be either 1 (enable) or 0
           (disable).  The default value of box is 0.

       shadowx, shadowy
           The x and y offsets for the text shadow position with respect to the position of the text. They can
           be either positive or negative values. Default value for both is "0".

       shadowcolor
           The color to be used for drawing a shadow behind the drawn text.  It can be a color name (e.g.
           "yellow") or a string in the 0xRRGGBB[AA] form (e.g. "0xff00ff"), possibly followed by an alpha
           specifier.  The default value of shadowcolor is "black".

       ft_load_flags
           Flags to be used for loading the fonts.

           The flags map the corresponding flags supported by libfreetype, and are a combination of the
           following values:

           default
           no_scale
           no_hinting
           render
           no_bitmap
           vertical_layout
           force_autohint
           crop_bitmap
           pedantic
           ignore_global_advance_width
           no_recurse
           ignore_transform
           monochrome
           linear_design
           no_autohint
           end table

           Default value is "render".

           For more information consult the documentation for the FT_LOAD_* libfreetype flags.

       tabsize
           The size in number of spaces to use for rendering the tab.  Default value is 4.

       fix_bounds
           If true, check and fix text coords to avoid clipping.

       For example the command:

               drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text'"

       will draw "Test Text" with font FreeSerif, using the default values for the optional parameters.

       The command:

               drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSerif.ttf: text='Test Text':\
                         x=100: y=50: fontsize=24: fontcolor=yellow@0.2: box=1: boxcolor=red@0.2"

       will draw 'Test Text' with font FreeSerif of size 24 at position x=100 and y=50 (counting from the top-
       left corner of the screen), text is yellow with a red box around it. Both the text and the box have an
       opacity of 20%.

       Note that the double quotes are not necessary if spaces are not used within the parameter list.

       For more information about libfreetype, check: <http://www.freetype.org/>.

   fade
       Apply fade-in/out effect to input video.

       It accepts the parameters: type:start_frame:nb_frames

       type specifies if the effect type, can be either "in" for fade-in, or "out" for a fade-out effect.

       start_frame specifies the number of the start frame for starting to apply the fade effect.

       nb_frames specifies the number of frames for which the fade effect has to last. At the end of the fade-in
       effect the output video will have the same intensity as the input video, at the end of the fade-out
       transition the output video will be completely black.

       A few usage examples follow, usable too as test scenarios.

               # fade in first 30 frames of video
               fade=in:0:30

               # fade out last 45 frames of a 200-frame video
               fade=out:155:45

               # fade in first 25 frames and fade out last 25 frames of a 1000-frame video
               fade=in:0:25, fade=out:975:25

               # make first 5 frames black, then fade in from frame 5-24
               fade=in:5:20

   fieldorder
       Transform the field order of the input video.

       It accepts one parameter which specifies the required field order that the input interlaced video will be
       transformed to. The parameter can assume one of the following values:

       0 or bff
           output bottom field first

       1 or tff
           output top field first

       Default value is "tff".

       Transformation is achieved by shifting the picture content up or down by one line, and filling the
       remaining line with appropriate picture content.  This method is consistent with most broadcast field
       order converters.

       If the input video is not flagged as being interlaced, or it is already flagged as being of the required
       output field order then this filter does not alter the incoming video.

       This filter is very useful when converting to or from PAL DV material, which is bottom field first.

       For example:

               ./avconv -i in.vob -vf "fieldorder=bff" out.dv

   fifo
       Buffer input images and send them when they are requested.

       This filter is mainly useful when auto-inserted by the libavfilter framework.

       The filter does not take parameters.

   format
       Convert the input video to one of the specified pixel formats.  Libavfilter will try to pick one that is
       supported for the input to the next filter.

       The filter accepts a list of pixel format names, separated by ":", for example "yuv420p:monow:rgb24".

       Some examples follow:

               # convert the input video to the format "yuv420p"
               format=yuv420p

               # convert the input video to any of the formats in the list
               format=yuv420p:yuv444p:yuv410p

   fps
       Convert the video to specified constant framerate by duplicating or dropping frames as necessary.

       This filter accepts the following named parameters:

       fps Desired output framerate.

   frei0r
       Apply a frei0r effect to the input video.

       To enable compilation of this filter you need to install the frei0r header and configure Libav with
       --enable-frei0r.

       The filter supports the syntax:

               <filter_name>[{:|=}<param1>:<param2>:...:<paramN>]

       filter_name is the name to the frei0r effect to load. If the environment variable FREI0R_PATH is defined,
       the frei0r effect is searched in each one of the directories specified by the colon separated list in
       FREIOR_PATH, otherwise in the standard frei0r paths, which are in this order: HOME/.frei0r-1/lib/,
       /usr/local/lib/frei0r-1/, /usr/lib/frei0r-1/.

       param1, param2, ... , paramN specify the parameters for the frei0r effect.

       A frei0r effect parameter can be a boolean (whose values are specified with "y" and "n"), a double, a
       color (specified by the syntax R/G/B, R, G, and B being float numbers from 0.0 to 1.0) or by an
       "av_parse_color()" color description), a position (specified by the syntax X/Y, X and Y being float
       numbers) and a string.

       The number and kind of parameters depend on the loaded effect. If an effect parameter is not specified
       the default value is set.

       Some examples follow:

               # apply the distort0r effect, set the first two double parameters
               frei0r=distort0r:0.5:0.01

               # apply the colordistance effect, takes a color as first parameter
               frei0r=colordistance:0.2/0.3/0.4
               frei0r=colordistance:violet
               frei0r=colordistance:0x112233

               # apply the perspective effect, specify the top left and top right
               # image positions
               frei0r=perspective:0.2/0.2:0.8/0.2

       For more information see: <http://piksel.org/frei0r>

   gradfun
       Fix the banding artifacts that are sometimes introduced into nearly flat regions by truncation to 8bit
       colordepth.  Interpolate the gradients that should go where the bands are, and dither them.

       This filter is designed for playback only.  Do not use it prior to lossy compression, because compression
       tends to lose the dither and bring back the bands.

       The filter takes two optional parameters, separated by ':': strength:radius

       strength is the maximum amount by which the filter will change any one pixel. Also the threshold for
       detecting nearly flat regions. Acceptable values range from .51 to 255, default value is 1.2, out-of-
       range values will be clipped to the valid range.

       radius is the neighborhood to fit the gradient to. A larger radius makes for smoother gradients, but also
       prevents the filter from modifying the pixels near detailed regions. Acceptable values are 8-32, default
       value is 16, out-of-range values will be clipped to the valid range.

               # default parameters
               gradfun=1.2:16

               # omitting radius
               gradfun=1.2

   hflip
       Flip the input video horizontally.

       For example to horizontally flip the input video with avconv:

               avconv -i in.avi -vf "hflip" out.avi

   hqdn3d
       High precision/quality 3d denoise filter. This filter aims to reduce image noise producing smooth images
       and making still images really still. It should enhance compressibility.

       It accepts the following optional parameters: luma_spatial:chroma_spatial:luma_tmp:chroma_tmp

       luma_spatial
           a non-negative float number which specifies spatial luma strength, defaults to 4.0

       chroma_spatial
           a non-negative float number which specifies spatial chroma strength, defaults to 3.0*luma_spatial/4.0

       luma_tmp
           a float number which specifies luma temporal strength, defaults to 6.0*luma_spatial/4.0

       chroma_tmp
           a float number which specifies chroma temporal strength, defaults to
           luma_tmp*chroma_spatial/luma_spatial

   lut, lutrgb, lutyuv
       Compute a look-up table for binding each pixel component input value to an output value, and apply it to
       input video.

       lutyuv applies a lookup table to a YUV input video, lutrgb to an RGB input video.

       These filters accept in input a ":"-separated list of options, which specify the expressions used for
       computing the lookup table for the corresponding pixel component values.

       The lut filter requires either YUV or RGB pixel formats in input, and accepts the options:

       c0 (first  pixel component)
       c1 (second pixel component)
       c2 (third  pixel component)
       c3 (fourth pixel component, corresponds to the alpha component)

       The exact component associated to each option depends on the format in input.

       The lutrgb filter requires RGB pixel formats in input, and accepts the options:

       r (red component)
       g (green component)
       b (blue component)
       a (alpha component)

       The lutyuv filter requires YUV pixel formats in input, and accepts the options:

       y (Y/luminance component)
       u (U/Cb component)
       v (V/Cr component)
       a (alpha component)

       The expressions can contain the following constants and functions:

       E, PI, PHI
           the corresponding mathematical approximated values for e (euler number), pi (greek PI), PHI (golden
           ratio)

       w, h
           the input width and height

       val input value for the pixel component

       clipval
           the input value clipped in the minval-maxval range

       maxval
           maximum value for the pixel component

       minval
           minimum value for the pixel component

       negval
           the negated value for the pixel component value clipped in the minval-maxval range , it corresponds
           to the expression "maxval-clipval+minval"

       clip(val)
           the computed value in val clipped in the minval-maxval range

       gammaval(gamma)
           the computed gamma correction value of the pixel component value clipped in the minval-maxval range,
           corresponds to the expression "pow((clipval-minval)/(maxval-minval),gamma)*(maxval-minval)+minval"

       All expressions default to "val".

       Some examples follow:

               # negate input video
               lutrgb="r=maxval+minval-val:g=maxval+minval-val:b=maxval+minval-val"
               lutyuv="y=maxval+minval-val:u=maxval+minval-val:v=maxval+minval-val"

               # the above is the same as
               lutrgb="r=negval:g=negval:b=negval"
               lutyuv="y=negval:u=negval:v=negval"

               # negate luminance
               lutyuv=negval

               # remove chroma components, turns the video into a graytone image
               lutyuv="u=128:v=128"

               # apply a luma burning effect
               lutyuv="y=2*val"

               # remove green and blue components
               lutrgb="g=0:b=0"

               # set a constant alpha channel value on input
               format=rgba,lutrgb=a="maxval-minval/2"

               # correct luminance gamma by a 0.5 factor
               lutyuv=y=gammaval(0.5)

   negate
       Negate input video.

       This filter accepts an integer in input, if non-zero it negates the alpha component (if available). The
       default value in input is 0.

       Force libavfilter not to use any of the specified pixel formats for the input to the next filter.

       The filter accepts a list of pixel format names, separated by ":", for example "yuv420p:monow:rgb24".

       Some examples follow:

               # force libavfilter to use a format different from "yuv420p" for the
               # input to the vflip filter
               noformat=yuv420p,vflip

               # convert the input video to any of the formats not contained in the list
               noformat=yuv420p:yuv444p:yuv410p

   null
       Pass the video source unchanged to the output.

   ocv
       Apply video transform using libopencv.

       To enable this filter install libopencv library and headers and configure Libav with --enable-libopencv.

       The filter takes the parameters: filter_name{:=}filter_params.

       filter_name is the name of the libopencv filter to apply.

       filter_params specifies the parameters to pass to the libopencv filter. If not specified the default
       values are assumed.

       Refer to the official libopencv documentation for more precise information:
       <http://opencv.willowgarage.com/documentation/c/image_filtering.html>

       Follows the list of supported libopencv filters.

       dilate

       Dilate an image by using a specific structuring element.  This filter corresponds to the libopencv
       function "cvDilate".

       It accepts the parameters: struct_el:nb_iterations.

       struct_el represents a structuring element, and has the syntax: colsxrows+anchor_xxanchor_y/shape

       cols and rows represent the number of columns and rows of the structuring element, anchor_x and anchor_y
       the anchor point, and shape the shape for the structuring element, and can be one of the values "rect",
       "cross", "ellipse", "custom".

       If the value for shape is "custom", it must be followed by a string of the form "=filename". The file
       with name filename is assumed to represent a binary image, with each printable character corresponding to
       a bright pixel. When a custom shape is used, cols and rows are ignored, the number or columns and rows of
       the read file are assumed instead.

       The default value for struct_el is "3x3+0x0/rect".

       nb_iterations specifies the number of times the transform is applied to the image, and defaults to 1.

       Follow some example:

               # use the default values
               ocv=dilate

               # dilate using a structuring element with a 5x5 cross, iterate two times
               ocv=dilate=5x5+2x2/cross:2

               # read the shape from the file diamond.shape, iterate two times
               # the file diamond.shape may contain a pattern of characters like this:
               #   *
               #  ***
               # *****
               #  ***
               #   *
               # the specified cols and rows are ignored (but not the anchor point coordinates)
               ocv=0x0+2x2/custom=diamond.shape:2

       erode

       Erode an image by using a specific structuring element.  This filter corresponds to the libopencv
       function "cvErode".

       The filter accepts the parameters: struct_el:nb_iterations, with the same syntax and semantics as the
       dilate filter.

       smooth

       Smooth the input video.

       The filter takes the following parameters: type:param1:param2:param3:param4.

       type is the type of smooth filter to apply, and can be one of the following values: "blur",
       "blur_no_scale", "median", "gaussian", "bilateral". The default value is "gaussian".

       param1, param2, param3, and param4 are parameters whose meanings depend on smooth type. param1 and param2
       accept integer positive values or 0, param3 and param4 accept float values.

       The default value for param1 is 3, the default value for the other parameters is 0.

       These parameters correspond to the parameters assigned to the libopencv function "cvSmooth".

   overlay
       Overlay one video on top of another.

       It takes two inputs and one output, the first input is the "main" video on which the second input is
       overlayed.

       It accepts the parameters: x:y.

       x is the x coordinate of the overlayed video on the main video, y is the y coordinate. The parameters are
       expressions containing the following parameters:

       main_w, main_h
           main input width and height

       W, H
           same as main_w and main_h

       overlay_w, overlay_h
           overlay input width and height

       w, h
           same as overlay_w and overlay_h

       Be aware that frames are taken from each input video in timestamp order, hence, if their initial
       timestamps differ, it is a a good idea to pass the two inputs through a setpts=PTS-STARTPTS filter to
       have them begin in the same zero timestamp, as it does the example for the movie filter.

       Follow some examples:

               # draw the overlay at 10 pixels from the bottom right
               # corner of the main video.
               overlay=main_w-overlay_w-10:main_h-overlay_h-10

               # insert a transparent PNG logo in the bottom left corner of the input
               avconv -i input -i logo -filter_complex 'overlay=10:main_h-overlay_h-10' output

               # insert 2 different transparent PNG logos (second logo on bottom
               # right corner):
               avconv -i input -i logo1 -i logo2 -filter_complex
               'overlay=10:H-h-10,overlay=W-w-10:H-h-10' output

               # add a transparent color layer on top of the main video,
               # WxH specifies the size of the main input to the overlay filter
               color=red.3:WxH [over]; [in][over] overlay [out]

       You can chain together more overlays but the efficiency of such approach is yet to be tested.

   pad
       Add paddings to the input image, and places the original input at the given coordinates x, y.

       It accepts the following parameters: width:height:x:y:color.

       The parameters width, height, x, and y are expressions containing the following constants:

       E, PI, PHI
           the corresponding mathematical approximated values for e (euler number), pi (greek PI), phi (golden
           ratio)

       in_w, in_h
           the input video width and height

       iw, ih
           same as in_w and in_h

       out_w, out_h
           the output width and height, that is the size of the padded area as specified by the width and height
           expressions

       ow, oh
           same as out_w and out_h

       x, y
           x and y offsets as specified by the x and y expressions, or NAN if not yet specified

       a   input display aspect ratio, same as iw / ih

       hsub, vsub
           horizontal and vertical chroma subsample values. For example for the pixel format "yuv422p" hsub is 2
           and vsub is 1.

       Follows the description of the accepted parameters.

       width, height
           Specify the size of the output image with the paddings added. If the value for width or height is 0,
           the corresponding input size is used for the output.

           The width expression can reference the value set by the height expression, and vice versa.

           The default value of width and height is 0.

       x, y
           Specify the offsets where to place the input image in the padded area with respect to the top/left
           border of the output image.

           The x expression can reference the value set by the y expression, and vice versa.

           The default value of x and y is 0.

       color
           Specify the color of the padded area, it can be the name of a color (case insensitive match) or a
           0xRRGGBB[AA] sequence.

           The default value of color is "black".

       Some examples follow:

               # Add paddings with color "violet" to the input video. Output video
               # size is 640x480, the top-left corner of the input video is placed at
               # column 0, row 40.
               pad=640:480:0:40:violet

               # pad the input to get an output with dimensions increased bt 3/2,
               # and put the input video at the center of the padded area
               pad="3/2*iw:3/2*ih:(ow-iw)/2:(oh-ih)/2"

               # pad the input to get a squared output with size equal to the maximum
               # value between the input width and height, and put the input video at
               # the center of the padded area
               pad="max(iw,ih):ow:(ow-iw)/2:(oh-ih)/2"

               # pad the input to get a final w/h ratio of 16:9
               pad="ih*16/9:ih:(ow-iw)/2:(oh-ih)/2"

               # double output size and put the input video in the bottom-right
               # corner of the output padded area
               pad="2*iw:2*ih:ow-iw:oh-ih"

   pixdesctest
       Pixel format descriptor test filter, mainly useful for internal testing. The output video should be equal
       to the input video.

       For example:

               format=monow, pixdesctest

       can be used to test the monowhite pixel format descriptor definition.

   scale
       Scale the input video to width:height and/or convert the image format.

       The parameters width and height are expressions containing the following constants:

       E, PI, PHI
           the corresponding mathematical approximated values for e (euler number), pi (greek PI), phi (golden
           ratio)

       in_w, in_h
           the input width and height

       iw, ih
           same as in_w and in_h

       out_w, out_h
           the output (cropped) width and height

       ow, oh
           same as out_w and out_h

       dar, a
           input display aspect ratio, same as iw / ih

       sar input sample aspect ratio

       hsub, vsub
           horizontal and vertical chroma subsample values. For example for the pixel format "yuv422p" hsub is 2
           and vsub is 1.

       If the input image format is different from the format requested by the next filter, the scale filter
       will convert the input to the requested format.

       If the value for width or height is 0, the respective input size is used for the output.

       If the value for width or height is -1, the scale filter will use, for the respective output size, a
       value that maintains the aspect ratio of the input image.

       The default value of width and height is 0.

       Some examples follow:

               # scale the input video to a size of 200x100.
               scale=200:100

               # scale the input to 2x
               scale=2*iw:2*ih
               # the above is the same as
               scale=2*in_w:2*in_h

               # scale the input to half size
               scale=iw/2:ih/2

               # increase the width, and set the height to the same size
               scale=3/2*iw:ow

               # seek for Greek harmony
               scale=iw:1/PHI*iw
               scale=ih*PHI:ih

               # increase the height, and set the width to 3/2 of the height
               scale=3/2*oh:3/5*ih

               # increase the size, but make the size a multiple of the chroma
               scale="trunc(3/2*iw/hsub)*hsub:trunc(3/2*ih/vsub)*vsub"

               # increase the width to a maximum of 500 pixels, keep the same input aspect ratio
               scale='min(500, iw*3/2):-1'

   select
       Select frames to pass in output.

       It accepts in input an expression, which is evaluated for each input frame. If the expression is
       evaluated to a non-zero value, the frame is selected and passed to the output, otherwise it is discarded.

       The expression can contain the following constants:

       PI  Greek PI

       PHI golden ratio

       E   Euler number

       n   the sequential number of the filtered frame, starting from 0

       selected_n
           the sequential number of the selected frame, starting from 0

       prev_selected_n
           the sequential number of the last selected frame, NAN if undefined

       TB  timebase of the input timestamps

       pts the PTS (Presentation TimeStamp) of the filtered video frame, expressed in TB units, NAN if undefined

       t   the PTS (Presentation TimeStamp) of the filtered video frame, expressed in seconds, NAN if undefined

       prev_pts
           the PTS of the previously filtered video frame, NAN if undefined

       prev_selected_pts
           the PTS of the last previously filtered video frame, NAN if undefined

       prev_selected_t
           the PTS of the last previously selected video frame, NAN if undefined

       start_pts
           the PTS of the first video frame in the video, NAN if undefined

       start_t
           the time of the first video frame in the video, NAN if undefined

       pict_type
           the type of the filtered frame, can assume one of the following values:

           I
           P
           B
           S
           SI
           SP
           BI
       interlace_type
           the frame interlace type, can assume one of the following values:

           PROGRESSIVE
               the frame is progressive (not interlaced)

           TOPFIRST
               the frame is top-field-first

           BOTTOMFIRST
               the frame is bottom-field-first

       key 1 if the filtered frame is a key-frame, 0 otherwise

       pos the position in the file of the filtered frame, -1 if the information is not available (e.g. for
           synthetic video)

       The default value of the select expression is "1".

       Some examples follow:

               # select all frames in input
               select

               # the above is the same as:
               select=1

               # skip all frames:
               select=0

               # select only I-frames
               select='eq(pict_type,I)'

               # select one frame every 100
               select='not(mod(n,100))'

               # select only frames contained in the 10-20 time interval
               select='gte(t,10)*lte(t,20)'

               # select only I frames contained in the 10-20 time interval
               select='gte(t,10)*lte(t,20)*eq(pict_type,I)'

               # select frames with a minimum distance of 10 seconds
               select='isnan(prev_selected_t)+gte(t-prev_selected_t,10)'

   setdar
       Set the Display Aspect Ratio for the filter output video.

       This is done by changing the specified Sample (aka Pixel) Aspect Ratio, according to the following
       equation: DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR

       Keep in mind that this filter does not modify the pixel dimensions of the video frame. Also the display
       aspect ratio set by this filter may be changed by later filters in the filterchain, e.g. in case of
       scaling or if another "setdar" or a "setsar" filter is applied.

       The filter accepts a parameter string which represents the wanted display aspect ratio.  The parameter
       can be a floating point number string, or an expression of the form num:den, where num and den are the
       numerator and denominator of the aspect ratio.  If the parameter is not specified, it is assumed the
       value "0:1".

       For example to change the display aspect ratio to 16:9, specify:

               setdar=16:9
               # the above is equivalent to
               setdar=1.77777

       See also the setsar filter documentation.

   setpts
       Change the PTS (presentation timestamp) of the input video frames.

       Accept in input an expression evaluated through the eval API, which can contain the following constants:

       PTS the presentation timestamp in input

       PI  Greek PI

       PHI golden ratio

       E   Euler number

       N   the count of the input frame, starting from 0.

       STARTPTS
           the PTS of the first video frame

       INTERLACED
           tell if the current frame is interlaced

       POS original position in the file of the frame, or undefined if undefined for the current frame

       PREV_INPTS
           previous input PTS

       PREV_OUTPTS
           previous output PTS

       Some examples follow:

               # start counting PTS from zero
               setpts=PTS-STARTPTS

               # fast motion
               setpts=0.5*PTS

               # slow motion
               setpts=2.0*PTS

               # fixed rate 25 fps
               setpts=N/(25*TB)

               # fixed rate 25 fps with some jitter
               setpts='1/(25*TB) * (N + 0.05 * sin(N*2*PI/25))'

   setsar
       Set the Sample (aka Pixel) Aspect Ratio for the filter output video.

       Note that as a consequence of the application of this filter, the output display aspect ratio will change
       according to the following equation: DAR = HORIZONTAL_RESOLUTION / VERTICAL_RESOLUTION * SAR

       Keep in mind that the sample aspect ratio set by this filter may be changed by later filters in the
       filterchain, e.g. if another "setsar" or a "setdar" filter is applied.

       The filter accepts a parameter string which represents the wanted sample aspect ratio.  The parameter can
       be a floating point number string, or an expression of the form num:den, where num and den are the
       numerator and denominator of the aspect ratio.  If the parameter is not specified, it is assumed the
       value "0:1".

       For example to change the sample aspect ratio to 10:11, specify:

               setsar=10:11

   settb
       Set the timebase to use for the output frames timestamps.  It is mainly useful for testing timebase
       configuration.

       It accepts in input an arithmetic expression representing a rational.  The expression can contain the
       constants "PI", "E", "PHI", "AVTB" (the default timebase), and "intb" (the input timebase).

       The default value for the input is "intb".

       Follow some examples.

               # set the timebase to 1/25
               settb=1/25

               # set the timebase to 1/10
               settb=0.1

               #set the timebase to 1001/1000
               settb=1+0.001

               #set the timebase to 2*intb
               settb=2*intb

               #set the default timebase value
               settb=AVTB

   showinfo
       Show a line containing various information for each input video frame.  The input video is not modified.

       The shown line contains a sequence of key/value pairs of the form key:value.

       A description of each shown parameter follows:

       n   sequential number of the input frame, starting from 0

       pts Presentation TimeStamp of the input frame, expressed as a number of time base units. The time base
           unit depends on the filter input pad.

       pts_time
           Presentation TimeStamp of the input frame, expressed as a number of seconds

       pos position of the frame in the input stream, -1 if this information in unavailable and/or meaningless
           (for example in case of synthetic video)

       fmt pixel format name

       sar sample aspect ratio of the input frame, expressed in the form num/den

       s   size of the input frame, expressed in the form widthxheight

       i   interlaced mode ("P" for "progressive", "T" for top field first, "B" for bottom field first)

       iskey
           1 if the frame is a key frame, 0 otherwise

       type
           picture type of the input frame ("I" for an I-frame, "P" for a P-frame, "B" for a B-frame, "?" for
           unknown type).  Check also the documentation of the "AVPictureType" enum and of the
           "av_get_picture_type_char" function defined in libavutil/avutil.h.

       checksum
           Adler-32 checksum of all the planes of the input frame

       plane_checksum
           Adler-32 checksum of each plane of the input frame, expressed in the form "[c0 c1 c2 c3]"

   split
       Split input video into several identical outputs.

       The filter accepts a single parameter which specifies the number of outputs. If unspecified, it defaults
       to 2.

       For example

               avconv -i INPUT -filter_complex split=5 OUTPUT

       will create 5 copies of the input video.

   transpose
       Transpose rows with columns in the input video and optionally flip it.

       It accepts a parameter representing an integer, which can assume the values:

       0   Rotate by 90 degrees counterclockwise and vertically flip (default), that is:

                   L.R     L.l
                   . . ->  . .
                   l.r     R.r

       1   Rotate by 90 degrees clockwise, that is:

                   L.R     l.L
                   . . ->  . .
                   l.r     r.R

       2   Rotate by 90 degrees counterclockwise, that is:

                   L.R     R.r
                   . . ->  . .
                   l.r     L.l

       3   Rotate by 90 degrees clockwise and vertically flip, that is:

                   L.R     r.R
                   . . ->  . .
                   l.r     l.L

   unsharp
       Sharpen or blur the input video.

       It accepts the following parameters:
       luma_msize_x:luma_msize_y:luma_amount:chroma_msize_x:chroma_msize_y:chroma_amount

       Negative values for the amount will blur the input video, while positive values will sharpen. All
       parameters are optional and default to the equivalent of the string '5:5:1.0:5:5:0.0'.

       luma_msize_x
           Set the luma matrix horizontal size. It can be an integer between 3 and 13, default value is 5.

       luma_msize_y
           Set the luma matrix vertical size. It can be an integer between 3 and 13, default value is 5.

       luma_amount
           Set the luma effect strength. It can be a float number between -2.0 and 5.0, default value is 1.0.

       chroma_msize_x
           Set the chroma matrix horizontal size. It can be an integer between 3 and 13, default value is 5.

       chroma_msize_y
           Set the chroma matrix vertical size. It can be an integer between 3 and 13, default value is 5.

       luma_amount
           Set the chroma effect strength. It can be a float number between -2.0 and 5.0, default value is 0.0.

               # Strong luma sharpen effect parameters
               unsharp=7:7:2.5

               # Strong blur of both luma and chroma parameters
               unsharp=7:7:-2:7:7:-2

               # Use the default values with B<avconv>
               ./avconv -i in.avi -vf "unsharp" out.mp4

   vflip
       Flip the input video vertically.

               ./avconv -i in.avi -vf "vflip" out.avi

   yadif
       Deinterlace the input video ("yadif" means "yet another deinterlacing filter").

       It accepts the optional parameters: mode:parity:auto.

       mode specifies the interlacing mode to adopt, accepts one of the following values:

       0   output 1 frame for each frame

       1   output 1 frame for each field

       2   like 0 but skips spatial interlacing check

       3   like 1 but skips spatial interlacing check

       Default value is 0.

       parity specifies the picture field parity assumed for the input interlaced video, accepts one of the
       following values:

       0   assume top field first

       1   assume bottom field first

       -1  enable automatic detection

       Default value is -1.  If interlacing is unknown or decoder does not export this information, top field
       first will be assumed.

       auto specifies if deinterlacer should trust the interlaced flag and only deinterlace frames marked as
       interlaced

       0   deinterlace all frames

       1   only deinterlace frames marked as interlaced

       Default value is 0.

VIDEO SOURCES

       Below is a description of the currently available video sources.

   buffer
       Buffer video frames, and make them available to the filter chain.

       This source is mainly intended for a programmatic use, in particular through the interface defined in
       libavfilter/vsrc_buffer.h.

       It accepts the following parameters:
       width:height:pix_fmt_string:timebase_num:timebase_den:sample_aspect_ratio_num:sample_aspect_ratio.den

       All the parameters need to be explicitly defined.

       Follows the list of the accepted parameters.

       width, height
           Specify the width and height of the buffered video frames.

       pix_fmt_string
           A string representing the pixel format of the buffered video frames.  It may be a number
           corresponding to a pixel format, or a pixel format name.

       timebase_num, timebase_den
           Specify numerator and denomitor of the timebase assumed by the timestamps of the buffered frames.

       sample_aspect_ratio.num, sample_aspect_ratio.den
           Specify numerator and denominator of the sample aspect ratio assumed by the video frames.

       For example:

               buffer=320:240:yuv410p:1:24:1:1

       will instruct the source to accept video frames with size 320x240 and with format "yuv410p", assuming
       1/24 as the timestamps timebase and square pixels (1:1 sample aspect ratio).  Since the pixel format with
       name "yuv410p" corresponds to the number 6 (check the enum AVPixelFormat definition in
       libavutil/pixfmt.h), this example corresponds to:

               buffer=320:240:6:1:24

   color
       Provide an uniformly colored input.

       It accepts the following parameters: color:frame_size:frame_rate

       Follows the description of the accepted parameters.

       color
           Specify the color of the source. It can be the name of a color (case insensitive match) or a
           0xRRGGBB[AA] sequence, possibly followed by an alpha specifier. The default value is "black".

       frame_size
           Specify the size of the sourced video, it may be a string of the form widthxheight, or the name of a
           size abbreviation. The default value is "320x240".

       frame_rate
           Specify the frame rate of the sourced video, as the number of frames generated per second. It has to
           be a string in the format frame_rate_num/frame_rate_den, an integer number, a float number or a valid
           video frame rate abbreviation. The default value is "25".

       For example the following graph description will generate a red source with an opacity of 0.2, with size
       "qcif" and a frame rate of 10 frames per second, which will be overlayed over the source connected to the
       pad with identifier "in".

               "color=red@0.2:qcif:10 [color]; [in][color] overlay [out]"

   movie
       Read a video stream from a movie container.

       Note that this source is a hack that bypasses the standard input path. It can be useful in applications
       that do not support arbitrary filter graphs, but its use is discouraged in those that do. Specifically in
       avconv this filter should never be used, the -filter_complex option fully replaces it.

       It accepts the syntax: movie_name[:options] where movie_name is the name of the resource to read (not
       necessarily a file but also a device or a stream accessed through some protocol), and options is an
       optional sequence of key=value pairs, separated by ":".

       The description of the accepted options follows.

       format_name, f
           Specifies the format assumed for the movie to read, and can be either the name of a container or an
           input device. If not specified the format is guessed from movie_name or by probing.

       seek_point, sp
           Specifies the seek point in seconds, the frames will be output starting from this seek point, the
           parameter is evaluated with "av_strtod" so the numerical value may be suffixed by an IS postfix.
           Default value is "0".

       stream_index, si
           Specifies the index of the video stream to read. If the value is -1, the best suited video stream
           will be automatically selected. Default value is "-1".

       This filter allows to overlay a second video on top of main input of a filtergraph as shown in this
       graph:

               input -----------> deltapts0 --> overlay --> output
                                                   ^
                                                   |
               movie --> scale--> deltapts1 -------+

       Some examples follow:

               # skip 3.2 seconds from the start of the avi file in.avi, and overlay it
               # on top of the input labelled as "in".
               movie=in.avi:seek_point=3.2, scale=180:-1, setpts=PTS-STARTPTS [movie];
               [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]

               # read from a video4linux2 device, and overlay it on top of the input
               # labelled as "in"
               movie=/dev/video0:f=video4linux2, scale=180:-1, setpts=PTS-STARTPTS [movie];
               [in] setpts=PTS-STARTPTS, [movie] overlay=16:16 [out]

   nullsrc
       Null video source, never return images. It is mainly useful as a template and to be employed in analysis
       / debugging tools.

       It accepts as optional parameter a string of the form width:height:timebase.

       width and height specify the size of the configured source. The default values of width and height are
       respectively 352 and 288 (corresponding to the CIF size format).

       timebase specifies an arithmetic expression representing a timebase. The expression can contain the
       constants "PI", "E", "PHI", "AVTB" (the default timebase), and defaults to the value "AVTB".

   frei0r_src
       Provide a frei0r source.

       To enable compilation of this filter you need to install the frei0r header and configure Libav with
       --enable-frei0r.

       The source supports the syntax:

               <size>:<rate>:<src_name>[{=|:}<param1>:<param2>:...:<paramN>]

       size is the size of the video to generate, may be a string of the form widthxheight or a frame size
       abbreviation.  rate is the rate of the video to generate, may be a string of the form num/den or a frame
       rate abbreviation.  src_name is the name to the frei0r source to load. For more information regarding
       frei0r and how to set the parameters read the section frei0r in the description of the video filters.

       Some examples follow:

               # generate a frei0r partik0l source with size 200x200 and framerate 10
               # which is overlayed on the overlay filter main input
               frei0r_src=200x200:10:partik0l=1234 [overlay]; [in][overlay] overlay

   rgbtestsrc, testsrc
       The "rgbtestsrc" source generates an RGB test pattern useful for detecting RGB vs BGR issues. You should
       see a red, green and blue stripe from top to bottom.

       The "testsrc" source generates a test video pattern, showing a color pattern, a scrolling gradient and a
       timestamp. This is mainly intended for testing purposes.

       Both sources accept an optional sequence of key=value pairs, separated by ":". The description of the
       accepted options follows.

       size, s
           Specify the size of the sourced video, it may be a string of the form widthxheight, or the name of a
           size abbreviation. The default value is "320x240".

       rate, r
           Specify the frame rate of the sourced video, as the number of frames generated per second. It has to
           be a string in the format frame_rate_num/frame_rate_den, an integer number, a float number or a valid
           video frame rate abbreviation. The default value is "25".

       sar Set the sample aspect ratio of the sourced video.

       duration
           Set the video duration of the sourced video. The accepted syntax is:

                   [-]HH[:MM[:SS[.m...]]]
                   [-]S+[.m...]

           See also the function "av_parse_time()".

           If not specified, or the expressed duration is negative, the video is supposed to be generated
           forever.

       For example the following:

               testsrc=duration=5.3:size=qcif:rate=10

       will generate a video with a duration of 5.3 seconds, with size 176x144 and a framerate of 10 frames per
       second.

VIDEO SINKS

       Below is a description of the currently available video sinks.

   buffersink
       Buffer video frames, and make them available to the end of the filter graph.

       This sink is intended for a programmatic use through the interface defined in libavfilter/buffersink.h.

   nullsink
       Null video sink, do absolutely nothing with the input video. It is mainly useful as a template and to be
       employed in analysis / debugging tools.

METADATA

       Libav is able to dump metadata from media files into a simple UTF-8-encoded INI-like text file and then
       load it back using the metadata muxer/demuxer.

       The file format is as follows:

       1.  A file consists of a header and a number of metadata tags divided into sections, each on its own
           line.

       2.  The header is a ';FFMETADATA' string, followed by a version number (now 1).

       3.  Metadata tags are of the form 'key=value'

       4.  Immediately after header follows global metadata

       5.  After global metadata there may be sections with per-stream/per-chapter metadata.

       6.  A section starts with the section name in uppercase (i.e. STREAM or CHAPTER) in brackets ('[', ']')
           and ends with next section or end of file.

       7.  At the beginning of a chapter section there may be an optional timebase to be used for start/end
           values. It must be in form 'TIMEBASE=num/den', where num and den are integers. If the timebase is
           missing then start/end times are assumed to be in milliseconds.  Next a chapter section must contain
           chapter start and end times in form 'START=num', 'END=num', where num is a positive integer.

       8.  Empty lines and lines starting with ';' or '#' are ignored.

       9.  Metadata keys or values containing special characters ('=', ';', '#', '\' and a newline) must be
           escaped with a backslash '\'.

       10. Note that whitespace in metadata (e.g. foo = bar) is considered to be a part of the tag (in the
           example above key is 'foo ', value is ' bar').

       A ffmetadata file might look like this:

               ;FFMETADATA1
               title=bike\\shed
               ;this is a comment
               artist=Libav troll team

               [CHAPTER]
               TIMEBASE=1/1000
               START=0
               #chapter ends at 0:01:00
               END=60000
               title=chapter \#1
               [STREAM]
               title=multi\
               line

SEE ALSO

       avplay(1), avprobe(1) and the Libav HTML documentation

AUTHORS

       The Libav developers

                                                   2016-12-07                                          AVCONV(1)