Provided by: libav-tools_0.8.1-0ubuntu1_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.

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 International System number postfixes,
       for example 'K', 'M', 'G'.  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.

       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
           Show help.

       -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 available codecs.

           The fields preceding the codec names have the following meanings:

           D   Decoding available

           E   Encoding available

           V/A/S
               Video/audio/subtitle codec

           S   Codec supports slices

           D   Codec supports direct rendering

           T   Codec can handle input truncated at random locations instead of only at frame
               boundaries

       -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.

   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).

       -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), (default = 25).

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

       -bt tolerance
           Set video bitrate tolerance (in bits, default 4000k).  Has a minimum value of:
           (target_bitrate/target_framerate).  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 min/max bitrate. Lowering tolerance too much has an adverse effect on
           quality.

       -maxrate bitrate
           Set max video bitrate (in bit/s).  Requires -bufsize to be set.

       -minrate bitrate
           Set min video bitrate (in bit/s).  Most useful in setting up a CBR encode:

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

           It is of little use elsewise.

       -bufsize size
           Set video buffer verifier buffer size (in bits).

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

       -same_quant
           Use same quantizer as source (implies VBR).

           Note that this is NOT SAME QUALITY. Do not use this option unless you know you need
           it.

       -pass n
           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 prefix (global)
           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.

       -g gop_size
           Set the group of pictures size.

       -vdt n
           Discard threshold.

       -qmin q
           minimum video quantizer scale (VBR)

       -qmax q
           maximum video quantizer scale (VBR)

       -qdiff q
           maximum difference between the quantizer scales (VBR)

       -qblur blur
           video quantizer scale blur (VBR) (range 0.0 - 1.0)

       -qcomp compression
           video quantizer scale compression (VBR) (default 0.5).  Constant of ratecontrol
           equation. Recommended range for default rc_eq: 0.0-1.0

       -lmin lambda
           minimum video lagrange factor (VBR)

       -lmax lambda
           max video lagrange factor (VBR)

       -mblmin lambda
           minimum macroblock quantizer scale (VBR)

       -mblmax lambda
           maximum macroblock quantizer scale (VBR)

           These four options (lmin, lmax, mblmin, 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

       -rc_init_cplx complexity
           initial complexity for single pass encoding

       -b_qfactor factor
           qp factor between P- and B-frames

       -i_qfactor factor
           qp factor between P- and I-frames

       -b_qoffset offset
           qp offset between P- and B-frames

       -i_qoffset offset
           qp offset between P- and I-frames

       -rc_eq equation
           Set rate control equation (see section "Expression Evaluation") (default =
           "tex^qComp").

           When computing the rate control equation expression, besides the standard functions
           defined in the section "Expression Evaluation", the following functions are available:

           bits2qp(bits)
           qp2bits(qp)

           and the following constants are available:

           iTex
           pTex
           tex
           mv
           fCode
           iCount
           mcVar
           var
           isI
           isP
           isB
           avgQP
           qComp
           avgIITex
           avgPITex
           avgPPTex
           avgBPTex
           avgTex
       -rc_override[:stream_specifier] override (output,per-stream)
           rate control override for specific intervals

       -me_method method
           Set motion estimation method to method.  Available methods are (from lowest to best
           quality):

           zero
               Try just the (0, 0) vector.

           phods
           log
           x1
           hex
           umh
           epzs
               (default method)

           full
               exhaustive search (slow and marginally better than epzs)

       -er n
           Set error resilience to n.

           1   FF_ER_CAREFUL (default)

           2   FF_ER_COMPLIANT

           3   FF_ER_AGGRESSIVE

           4   FF_ER_VERY_AGGRESSIVE

       -ec bit_mask
           Set error concealment to bit_mask. bit_mask is a bit mask of the following values:

           1   FF_EC_GUESS_MVS (default = enabled)

           2   FF_EC_DEBLOCK (default = enabled)

       -bf frames
           Use 'frames' B-frames (supported for MPEG-1, MPEG-2 and MPEG-4).

       -mbd mode
           macroblock decision

           0   FF_MB_DECISION_SIMPLE: Use mb_cmp (cannot change it yet in avconv).

           1   FF_MB_DECISION_BITS: Choose the one which needs the fewest bits.

           2   FF_MB_DECISION_RD: rate distortion

       -bug param
           Work around encoder bugs that are not auto-detected.

       -strict strictness
           How strictly to follow the standards.

       -deinterlace
           Deinterlace pictures.

       -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.

   Advanced Audio options:
       -atag fourcc/tag (output)
           Force audio tag/fourcc. This is an alias for "-tag:a".

       -audio_service_type type
           Set the type of service that the audio stream contains.

           ma  Main Audio Service (default)

           ef  Effects

           vi  Visually Impaired

           hi  Hearing Impaired

           di  Dialogue

           co  Commentary

           em  Emergency

           vo  Voice Over

           ka  Karaoke

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

       -sn (output)
           Disable subtitle recording.

   Audio/Video grab options
       -isync (global)
           Synchronize read on input.

   Advanced options
       -map [-]input_file_id[:stream_specifier][,sync_file_id[:stream_specifier]] (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.

           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.

       -ps size
           Set RTP payload size in bytes.

       -re (input)
           Read input at native frame rate. Mainly used to simulate a grab device.

       -threads count
           Thread count.

       -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.

       -copyts
           Copy timestamps from input to output.

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

       -shortest
           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 -vbsf h264_mp4toannexb -an out.h264

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

       -tag[:stream_specifier] codec_tag (output,per-stream)
           Force a tag/fourcc for matching streams.

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
           '-intra' 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 0.3 -map 0.2 -map 0.1 -map 0.0 -c copy test12.nut

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

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)
       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 ff* 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 ff* 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

   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 ff* 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.

   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

   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.

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

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 ff* 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

   video4linux and video4linux2
       Video4Linux and Video4Linux2 input video devices.

       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.

       Video4Linux and Video4Linux2 devices only support a limited set of widthxheight sizes and
       framerates. You can check which are supported for example with the command dov4l for
       Video4Linux devices and using -list_formats all for Video4Linux2 devices.

       If the size for the device is set to 0x0, the input device will try to autodetect the size
       to use.  Only for the video4linux2 device, if the frame rate is set to 0/0 the input
       device will use the frame rate value already set in the driver.

       Video4Linux support is deprecated since Linux 2.6.30, and will be dropped in later
       versions.

       Follow some usage examples of the video4linux devices with the ff* tools.

               # Grab and show the input of a video4linux device, frame rate is set
               # to the default of 25/1.
               avplay -s 320x240 -f video4linux /dev/video0

               # Grab and show the input of a video4linux2 device, autoadjust size.
               avplay -f video4linux2 /dev/video0

               # Grab and record the input of a video4linux2 device, autoadjust size,
               # frame rate value defaults to 0/0 so it is read from the video4linux2
               # driver.
               avconv -f video4linux2 -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 ommitted, 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 ff* 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 ff* tools will display the list of supported protocols.

       A description of the currently available protocols follows.

   applehttp
       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.  HTTP is default, specific protocol can be declared by
       specifying "+proto" after the applehttp URI scheme name, where proto is either "file" or
       "http".

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

   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 ff* 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.

   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>][/<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.).

       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:".

       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

   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.

       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). In order for this to be
       enabled, a maximum delay must be specified in 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

   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.

       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 ff* 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 -vbsf 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 "-vf" and "-af" options in avconv and avplay, and by the "av_parse_graph()" function
       defined in libavfilter/avfiltergraph.

       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.

       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>           ::= [<LINKNAMES>] <NAME> ["=" <ARGUMENTS>] [<LINKNAMES>]
               <FILTERCHAIN>      ::= <FILTER> [,<FILTERCHAIN>]
               <FILTERGRAPH>      ::= <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.

   anull
       Pass the audio source unchanged to the output.

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 libavcodec/audioconvert.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

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.

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.

       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

   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
               movie=logo.png [logo];
               [in][logo] overlay=10:main_h-overlay_h-10 [out]

               # insert 2 different transparent PNG logos (second logo on bottom
               # right corner):
               movie=logo1.png [logo1];
               movie=logo2.png [logo2];
               [in][logo1]       overlay=10:H-h-10 [in+logo1];
               [in+logo1][logo2] overlay=W-w-10:H-h-10 [out]

               # 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]"

   slicify
       Pass the images of input video on to next video filter as multiple slices.

               ./avconv -i in.avi -vf "slicify=32" out.avi

       The filter accepts the slice height as parameter. If the parameter is not specified it
       will use the default value of 16.

       Adding this in the beginning of filter chains should make filtering faster due to better
       use of the memory cache.

   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 PixelFormat 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.

       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.

   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

                                            2012-03-22                                  AVCONV(1)