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diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi new file mode 100644 index 0000000000..1ee42d82b4 --- /dev/null +++ b/doc/ffmpeg.texi @@ -0,0 +1,1322 @@ +\input texinfo @c -*- texinfo -*- + +@settitle ffmpeg Documentation +@titlepage +@center @titlefont{ffmpeg Documentation} +@end titlepage + +@top + +@contents + +@chapter Synopsis + +The generic syntax is: + +@example +@c man begin SYNOPSIS +ffmpeg [global options] [[infile options][@option{-i} @var{infile}]]... @{[outfile options] @var{outfile}@}... +@c man end +@end example + +@chapter Description +@c man begin DESCRIPTION + +ffmpeg 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. + +ffmpeg reads from an arbitrary number of input "files" (which can be regular +files, pipes, network streams, grabbing devices, etc.), specified by the +@code{-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 @code{-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 @code{0}, the second is @code{1} etc. Similarly, streams +within a file are referred to by their indices. E.g. @code{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. + +@itemize +@item +To set the video bitrate of the output file to 64kbit/s: +@example +ffmpeg -i input.avi -b:v 64k output.avi +@end example + +@item +To force the frame rate of the output file to 24 fps: +@example +ffmpeg -i input.avi -r 24 output.avi +@end example + +@item +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: +@example +ffmpeg -r 1 -i input.m2v -r 24 output.avi +@end example +@end itemize + +The format option may be needed for raw input files. + +@c man end DESCRIPTION + +@chapter Detailed description +@c man begin DETAILED DESCRIPTION + +The transcoding process in @command{ffmpeg} for each output can be described by +the following diagram: + +@example + _______ ______________ _________ ______________ ________ +| | | | | | | | | | +| input | demuxer | encoded data | decoder | decoded | encoder | encoded data | muxer | output | +| file | ---------> | packets | ---------> | frames | ---------> | packets | -------> | file | +|_______| |______________| |_________| |______________| |________| + +@end example + +@command{ffmpeg} calls the libavformat library (containing demuxers) to read +input files and get packets containing encoded data from them. When there are +multiple input files, @command{ffmpeg} tries to keep them synchronized by +tracking lowest timestamp on any active input stream. + +Encoded packets are then passed to the decoder (unless streamcopy is selected +for the stream, see further for a description). The decoder produces +uncompressed frames (raw video/PCM audio/...) which can be processed further by +filtering (see next section). After filtering the frames are passed to the +encoder, which encodes them and outputs encoded packets again. Finally those are +passed to the muxer, which writes the encoded packets to the output file. + +@section Filtering +Before encoding, @command{ffmpeg} can process raw audio and video frames using +filters from the libavfilter library. Several chained filters form a filter +graph. @command{ffmpeg} distinguishes between two types of filtergraphs - +simple and complex. + +@subsection Simple filtergraphs +Simple filtergraphs are those that have exactly one input and output, both of +the same type. In the above diagram they can be represented by simply inserting +an additional step between decoding and encoding: + +@example + _________ __________ ______________ +| | | | | | +| decoded | simple filtergraph | filtered | encoder | encoded data | +| frames | -------------------> | frames | ---------> | packets | +|_________| |__________| |______________| + +@end example + +Simple filtergraphs are configured with the per-stream @option{-filter} option +(with @option{-vf} and @option{-af} aliases for video and audio respectively). +A simple filtergraph for video can look for example like this: + +@example + _______ _____________ _______ _____ ________ +| | | | | | | | | | +| input | ---> | deinterlace | ---> | scale | ---> | fps | ---> | output | +|_______| |_____________| |_______| |_____| |________| + +@end example + +Note that some filters change frame properties but not frame contents. E.g. the +@code{fps} filter in the example above changes number of frames, but does not +touch the frame contents. Another example is the @code{setpts} filter, which +only sets timestamps and otherwise passes the frames unchanged. + +@subsection Complex filtergraphs +Complex filtergraphs are those which cannot be described as simply a linear +processing chain applied to one stream. This is the case e.g. when the graph has +more than one input and/or output, or when output stream type is different from +input. They can be represented with the following diagram: + +@example + _________ +| | +| input 0 |\ __________ +|_________| \ | | + \ _________ /| output 0 | + \ | | / |__________| + _________ \| complex | / +| | | |/ +| input 1 |---->| filter |\ +|_________| | | \ __________ + /| graph | \ | | + / | | \| output 1 | + _________ / |_________| |__________| +| | / +| input 2 |/ +|_________| + +@end example + +Complex filtergraphs are configured with the @option{-filter_complex} option. +Note that this option is global, since a complex filtergraph by its nature +cannot be unambiguously associated with a single stream or file. + +A trivial example of a complex filtergraph is the @code{overlay} filter, which +has two video inputs and one video output, containing one video overlaid on top +of the other. Its audio counterpart is the @code{amix} filter. + +@section Stream copy +Stream copy is a mode selected by supplying the @code{copy} parameter to the +@option{-codec} option. It makes @command{ffmpeg} omit the decoding and encoding +step for the specified stream, so it does only demuxing and muxing. It is useful +for changing the container format or modifying container-level metadata. The +diagram above will in this case simplify to this: + +@example + _______ ______________ ________ +| | | | | | +| input | demuxer | encoded data | muxer | output | +| file | ---------> | packets | -------> | file | +|_______| |______________| |________| + +@end example + +Since there is no decoding or encoding, it is very fast and there is no quality +loss. However it might not work in some cases because of many factors. Applying +filters is obviously also impossible, since filters work on uncompressed data. + +@c man end DETAILED DESCRIPTION + +@chapter Stream selection +@c man begin STREAM SELECTION + +By default ffmpeg includes only one stream of each type (video, audio, subtitle) +present in the input files and adds them to each output file. It picks the +"best" of each based upon the following criteria; for video it is the stream +with the highest resolution, for audio the stream with the most channels, for +subtitle it's the first subtitle stream. In the case where several streams of +the same type rate equally, the lowest numbered stream is chosen. + +You can disable some of those defaults by using @code{-vn/-an/-sn} options. For +full manual control, use the @code{-map} option, which disables the defaults just +described. + +@c man end STREAM SELECTION + +@chapter Options +@c man begin OPTIONS + +@include avtools-common-opts.texi + +@section Main options + +@table @option + +@item -f @var{fmt} (@emph{input/output}) +Force input or output file format. The format is normally auto detected for input +files and guessed from file extension for output files, so this option is not +needed in most cases. + +@item -i @var{filename} (@emph{input}) +input file name + +@item -y (@emph{global}) +Overwrite output files without asking. + +@item -n (@emph{global}) +Do not overwrite output files but exit if file exists. + +@item -c[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream}) +@itemx -codec[:@var{stream_specifier}] @var{codec} (@emph{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. @var{codec} is the name of a +decoder/encoder or a special value @code{copy} (output only) to indicate that +the stream is not to be re-encoded. + +For example +@example +ffmpeg -i INPUT -map 0 -c:v libx264 -c:a copy OUTPUT +@end example +encodes all video streams with libx264 and copies all audio streams. + +For each stream, the last matching @code{c} option is applied, so +@example +ffmpeg -i INPUT -map 0 -c copy -c:v:1 libx264 -c:a:137 libvorbis OUTPUT +@end example +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. + +@item -t @var{duration} (@emph{output}) +Stop writing the output after its duration reaches @var{duration}. +@var{duration} may be a number in seconds, or in @code{hh:mm:ss[.xxx]} form. + +@item -fs @var{limit_size} (@emph{output}) +Set the file size limit, expressed in bytes. + +@item -ss @var{position} (@emph{input/output}) +When used as an input option (before @code{-i}), seeks in this input file to +@var{position}. When used as an output option (before an output filename), +decodes but discards input until the timestamps reach @var{position}. This is +slower, but more accurate. + +@var{position} may be either in seconds or in @code{hh:mm:ss[.xxx]} form. + +@item -itsoffset @var{offset} (@emph{input}) +Set the input time offset in seconds. +@code{[-]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 @var{offset} seconds. + +@item -timestamp @var{time} (@emph{output}) +Set the recording timestamp in the container. +The syntax for @var{time} is: +@example +now|([(YYYY-MM-DD|YYYYMMDD)[T|t| ]]((HH:MM:SS[.m...])|(HHMMSS[.m...]))[Z|z]) +@end example +If the value is "now" it takes the current time. +Time is local time unless 'Z' or 'z' is appended, in which case it is +interpreted as UTC. +If the year-month-day part is not specified it takes the current +year-month-day. + +@item -metadata[:metadata_specifier] @var{key}=@var{value} (@emph{output,per-metadata}) +Set a metadata key/value pair. + +An optional @var{metadata_specifier} may be given to set metadata +on streams or chapters. See @code{-map_metadata} documentation for +details. + +This option overrides metadata set with @code{-map_metadata}. It is +also possible to delete metadata by using an empty value. + +For example, for setting the title in the output file: +@example +ffmpeg -i in.avi -metadata title="my title" out.flv +@end example + +To set the language of the first audio stream: +@example +ffmpeg -i INPUT -metadata:s:a:1 language=eng OUTPUT +@end example + +@item -target @var{type} (@emph{output}) +Specify target file type (@code{vcd}, @code{svcd}, @code{dvd}, @code{dv}, +@code{dv50}). @var{type} may be prefixed with @code{pal-}, @code{ntsc-} or +@code{film-} to use the corresponding standard. All the format options +(bitrate, codecs, buffer sizes) are then set automatically. You can just type: + +@example +ffmpeg -i myfile.avi -target vcd /tmp/vcd.mpg +@end example + +Nevertheless you can specify additional options as long as you know +they do not conflict with the standard, as in: + +@example +ffmpeg -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg +@end example + +@item -dframes @var{number} (@emph{output}) +Set the number of data frames to record. This is an alias for @code{-frames:d}. + +@item -frames[:@var{stream_specifier}] @var{framecount} (@emph{output,per-stream}) +Stop writing to the stream after @var{framecount} frames. + +@item -q[:@var{stream_specifier}] @var{q} (@emph{output,per-stream}) +@itemx -qscale[:@var{stream_specifier}] @var{q} (@emph{output,per-stream}) +Use fixed quality scale (VBR). The meaning of @var{q} is +codec-dependent. + +@item -filter[:@var{stream_specifier}] @var{filter_graph} (@emph{output,per-stream}) +@var{filter_graph} is a description of the filter graph to apply to +the stream. Use @code{-filters} to show all the available filters +(including also sources and sinks). + +See also the @option{-filter_complex} option if you want to create filter graphs +with multiple inputs and/or outputs. +@item -pre[:@var{stream_specifier}] @var{preset_name} (@emph{output,per-stream}) +Specify the preset for matching stream(s). + +@item -stats (@emph{global}) +Print encoding progress/statistics. On by default. + +@item -progress @var{url} (@emph{global}) +Send program-friendly progress information to @var{url}. + +Progress information is written approximately every second and at the end of +the encoding process. It is made of "@var{key}=@var{value}" lines. @var{key} +consists of only alphanumeric characters. The last key of a sequence of +progress information is always "progress". + +@item -stdin +Enable interaction on standard input. On by default unless standard input is +used as an input. + +Useful, for example, if ffmpeg is in the background process group. Roughly +the same result can be achieved with @code{ffmpeg ... < /dev/null} but it +requires a shell. + +@item -debug_ts (@emph{global}) +Print timestamp information. It is off by default. This option is +mostly useful for testing and debugging purposes, and the output +format may change from one version to another, so it should not be +employed by portable scripts. + +See also the option @code{-fdebug ts}. + +@item -attach @var{filename} (@emph{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 @code{-map} or automatic mappings). + +Note that for Matroska you also have to set the mimetype metadata tag: +@example +ffmpeg -i INPUT -attach DejaVuSans.ttf -metadata:s:2 mimetype=application/x-truetype-font out.mkv +@end example +(assuming that the attachment stream will be third in the output file). + +@item -dump_attachment[:@var{stream_specifier}] @var{filename} (@emph{input,per-stream}) +Extract the matching attachment stream into a file named @var{filename}. If +@var{filename} is empty, then the value of the @code{filename} metadata tag +will be used. + +E.g. to extract the first attachment to a file named 'out.ttf': +@example +ffmpeg -dump_attachment:t:0 out.ttf INPUT +@end example +To extract all attachments to files determined by the @code{filename} tag: +@example +ffmpeg -dump_attachment:t "" INPUT +@end example + +Technical note -- attachments are implemented as codec extradata, so this +option can actually be used to extract extradata from any stream, not just +attachments. + +@end table + +@section Video Options + +@table @option +@item -vframes @var{number} (@emph{output}) +Set the number of video frames to record. This is an alias for @code{-frames:v}. +@item -r[:@var{stream_specifier}] @var{fps} (@emph{input/output,per-stream}) +Set frame rate (Hz value, fraction or abbreviation). + +As an input option, ignore any timestamps stored in the file and instead +generate timestamps assuming constant frame rate @var{fps}. + +As an output option, duplicate or drop input frames to achieve constant output +frame rate @var{fps} (note that this actually causes the @code{fps} filter to be +inserted to the end of the corresponding filtergraph). + +@item -s[:@var{stream_specifier}] @var{size} (@emph{input/output,per-stream}) +Set frame size. + +As an input option, this is a shortcut for the @option{video_size} private +option, recognized by some demuxers for which the frame size is either not +stored in the file or is configurable -- e.g. raw video or video grabbers. + +As an output option, this inserts the @code{scale} video filter to the +@emph{end} of the corresponding filtergraph. Please use the @code{scale} filter +directly to insert it at the beginning or some other place. + +The format is @samp{wxh} (default - same as source). + +@item -aspect[:@var{stream_specifier}] @var{aspect} (@emph{output,per-stream}) +Set the video display aspect ratio specified by @var{aspect}. + +@var{aspect} can be a floating point number string, or a string of the +form @var{num}:@var{den}, where @var{num} and @var{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. + +@item -croptop @var{size} +@item -cropbottom @var{size} +@item -cropleft @var{size} +@item -cropright @var{size} +All the crop options have been removed. Use -vf +crop=width:height:x:y instead. + +@item -padtop @var{size} +@item -padbottom @var{size} +@item -padleft @var{size} +@item -padright @var{size} +@item -padcolor @var{hex_color} +All the pad options have been removed. Use -vf +pad=width:height:x:y:color instead. + +@item -vn (@emph{output}) +Disable video recording. + +@item -vcodec @var{codec} (@emph{output}) +Set the video codec. This is an alias for @code{-codec:v}. +@item -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. + +@item -pass @var{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: +@example +ffmpeg -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y NUL +ffmpeg -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null +@end example + +@item -passlogfile @var{prefix} (@emph{global}) +Set two-pass log file name prefix to @var{prefix}, the default file name +prefix is ``ffmpeg2pass''. The complete file name will be +@file{PREFIX-N.log}, where N is a number specific to the output +stream + +@item -vlang @var{code} +Set the ISO 639 language code (3 letters) of the current video stream. + +@item -vf @var{filter_graph} (@emph{output}) +@var{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 @code{-filter:v}. + +@end table + +@section Advanced Video Options + +@table @option +@item -pix_fmt[:@var{stream_specifier}] @var{format} (@emph{input/output,per-stream}) +Set pixel format. Use @code{-pix_fmts} to show all the supported +pixel formats. +If the selected pixel format can not be selected, ffmpeg will print a +warning and select the best pixel format supported by the encoder. +If @var{pix_fmt} is prefixed by a @code{+}, ffmpeg will exit with an error +if the requested pixel format can not be selected, and automatic conversions +inside filter graphs are disabled. +If @var{pix_fmt} is a single @code{+}, ffmpeg selects the same pixel format +as the input (or graph output) and automatic conversions are disabled. + +@item -sws_flags @var{flags} (@emph{input/output}) +Set SwScaler flags. +@item -vdt @var{n} +Discard threshold. + +@item -rc_override[:@var{stream_specifier}] @var{override} (@emph{output,per-stream}) +Rate control override for specific intervals, formatted as "int,int,int" +list separated with slashes. Two first values are the beginning and +end frame numbers, last one is quantizer to use if positive, or quality +factor if negative. + +@item -deinterlace +Deinterlace pictures. +This option is deprecated since the deinterlacing is very low quality. +Use the yadif filter with @code{-filter:v yadif}. +@item -ilme +Force interlacing support in encoder (MPEG-2 and MPEG-4 only). +Use this option if your input file is interlaced and you want +to keep the interlaced format for minimum losses. +The alternative is to deinterlace the input stream with +@option{-deinterlace}, but deinterlacing introduces losses. +@item -psnr +Calculate PSNR of compressed frames. +@item -vstats +Dump video coding statistics to @file{vstats_HHMMSS.log}. +@item -vstats_file @var{file} +Dump video coding statistics to @var{file}. +@item -top[:@var{stream_specifier}] @var{n} (@emph{output,per-stream}) +top=1/bottom=0/auto=-1 field first +@item -dc @var{precision} +Intra_dc_precision. +@item -vtag @var{fourcc/tag} (@emph{output}) +Force video tag/fourcc. This is an alias for @code{-tag:v}. +@item -qphist (@emph{global}) +Show QP histogram +@item -vbsf @var{bitstream_filter} +Deprecated see -bsf +@item -force_key_frames[:@var{stream_specifier}] @var{time}[,@var{time}...] (@emph{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. + +@item -copyinkf[:@var{stream_specifier}] (@emph{output,per-stream}) +When doing stream copy, copy also non-key frames found at the +beginning. +@end table + +@section Audio Options + +@table @option +@item -aframes @var{number} (@emph{output}) +Set the number of audio frames to record. This is an alias for @code{-frames:a}. +@item -ar[:@var{stream_specifier}] @var{freq} (@emph{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. +@item -aq @var{q} (@emph{output}) +Set the audio quality (codec-specific, VBR). This is an alias for -q:a. +@item -ac[:@var{stream_specifier}] @var{channels} (@emph{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. +@item -an (@emph{output}) +Disable audio recording. +@item -acodec @var{codec} (@emph{input/output}) +Set the audio codec. This is an alias for @code{-codec:a}. +@item -sample_fmt[:@var{stream_specifier}] @var{sample_fmt} (@emph{output,per-stream}) +Set the audio sample format. Use @code{-sample_fmts} to get a list +of supported sample formats. +@item -af @var{filter_graph} (@emph{output}) +@var{filter_graph} is a description of the filter graph to apply to +the input audio. +Use the option "-filters" to show all the available filters (including +also sources and sinks). This is an alias for @code{-filter:a}. +@end table + +@section Advanced Audio options: + +@table @option +@item -atag @var{fourcc/tag} (@emph{output}) +Force audio tag/fourcc. This is an alias for @code{-tag:a}. +@item -absf @var{bitstream_filter} +Deprecated, see -bsf +@end table + +@section Subtitle options: + +@table @option +@item -slang @var{code} +Set the ISO 639 language code (3 letters) of the current subtitle stream. +@item -scodec @var{codec} (@emph{input/output}) +Set the subtitle codec. This is an alias for @code{-codec:s}. +@item -sn (@emph{output}) +Disable subtitle recording. +@item -sbsf @var{bitstream_filter} +Deprecated, see -bsf +@end table + +@section Audio/Video grab options + +@table @option +@item -isync (@emph{global}) +Synchronize read on input. +@end table + +@section Advanced options + +@table @option +@item -map [-]@var{input_file_id}[:@var{stream_specifier}][,@var{sync_file_id}[:@var{stream_specifier}]] | @var{[linklabel]} (@emph{output}) + +Designate one or more input streams as a source for the output file. Each input +stream is identified by the input file index @var{input_file_id} and +the input stream index @var{input_stream_id} within the input +file. Both indices start at 0. If specified, +@var{sync_file_id}:@var{stream_specifier} sets which input stream +is used as a presentation sync reference. + +The first @code{-map} option on the command line specifies the +source for output stream 0, the second @code{-map} option specifies +the source for output stream 1, etc. + +A @code{-} character before the stream identifier creates a "negative" mapping. +It disables matching streams from already created mappings. + +An alternative @var{[linklabel]} form will map outputs from complex filter +graphs (see the @option{-filter_complex} option) to the output file. +@var{linklabel} must correspond to a defined output link label in the graph. + +For example, to map ALL streams from the first input file to output +@example +ffmpeg -i INPUT -map 0 output +@end example + +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 +@code{-map} to select which streams to place in an output file. For +example: +@example +ffmpeg -i INPUT -map 0:1 out.wav +@end example +will map the input stream in @file{INPUT} identified by "0:1" to +the (single) output stream in @file{out.wav}. + +For example, to select the stream with index 2 from input file +@file{a.mov} (specified by the identifier "0:2"), and stream with +index 6 from input @file{b.mov} (specified by the identifier "1:6"), +and copy them to the output file @file{out.mov}: +@example +ffmpeg -i a.mov -i b.mov -c copy -map 0:2 -map 1:6 out.mov +@end example + +To select all video and the third audio stream from an input file: +@example +ffmpeg -i INPUT -map 0:v -map 0:a:2 OUTPUT +@end example + +To map all the streams except the second audio, use negative mappings +@example +ffmpeg -i INPUT -map 0 -map -0:a:1 OUTPUT +@end example + +Note that using this option disables the default mappings for this output file. + +@item -map_channel [@var{input_file_id}.@var{stream_specifier}.@var{channel_id}|-1][:@var{output_file_id}.@var{stream_specifier}] +Map an audio channel from a given input to an output. If +@var{output_file_id}.@var{stream_specifier} is not set, the audio channel will +be mapped on all the audio streams. + +Using "-1" instead of +@var{input_file_id}.@var{stream_specifier}.@var{channel_id} will map a muted +channel. + +For example, assuming @var{INPUT} is a stereo audio file, you can switch the +two audio channels with the following command: +@example +ffmpeg -i INPUT -map_channel 0.0.1 -map_channel 0.0.0 OUTPUT +@end example + +If you want to mute the first channel and keep the second: +@example +ffmpeg -i INPUT -map_channel -1 -map_channel 0.0.1 OUTPUT +@end example + +The order of the "-map_channel" option specifies the order of the channels in +the output stream. The output channel layout is guessed from the number of +channels mapped (mono if one "-map_channel", stereo if two, etc.). Using "-ac" +in combination of "-map_channel" makes the channel gain levels to be updated if +input and output channel layouts don't match (for instance two "-map_channel" +options and "-ac 6"). + +You can also extract each channel of an input to specific outputs; the following +command extracts two channels of the @var{INPUT} audio stream (file 0, stream 0) +to the respective @var{OUTPUT_CH0} and @var{OUTPUT_CH1} outputs: +@example +ffmpeg -i INPUT -map_channel 0.0.0 OUTPUT_CH0 -map_channel 0.0.1 OUTPUT_CH1 +@end example + +The following example splits the channels of a stereo input into two separate +streams, which are put into the same output file: +@example +ffmpeg -i stereo.wav -map 0:0 -map 0:0 -map_channel 0.0.0:0.0 -map_channel 0.0.1:0.1 -y out.ogg +@end example + +Note that currently each output stream can only contain channels from a single +input stream; you can't for example use "-map_channel" to pick multiple input +audio channels contained in different streams (from the same or different files) +and merge them into a single output stream. It is therefore not currently +possible, for example, to turn two separate mono streams into a single stereo +stream. However splitting a stereo stream into two single channel mono streams +is possible. + +If you need this feature, a possible workaround is to use the @emph{amerge} +filter. For example, if you need to merge a media (here @file{input.mkv}) with 2 +mono audio streams into one single stereo channel audio stream (and keep the +video stream), you can use the following command: +@example +ffmpeg -i input.mkv -filter_complex "[0:1] [0:2] amerge" -c:a pcm_s16le -c:v copy output.mkv +@end example + +@item -map_metadata[:@var{metadata_spec_out}] @var{infile}[:@var{metadata_spec_in}] (@emph{output,per-metadata}) +Set metadata information of the next output file from @var{infile}. Note that +those are file indices (zero-based), not filenames. +Optional @var{metadata_spec_in/out} parameters specify, which metadata to copy. +A metadata specifier can have the following forms: +@table @option +@item @var{g} +global metadata, i.e. metadata that applies to the whole file + +@item @var{s}[:@var{stream_spec}] +per-stream metadata. @var{stream_spec} is a stream specifier as described +in the @ref{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. + +@item @var{c}:@var{chapter_index} +per-chapter metadata. @var{chapter_index} is the zero-based chapter index. + +@item @var{p}:@var{program_index} +per-program metadata. @var{program_index} is the zero-based program index. +@end table +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: +@example +ffmpeg -i in.ogg -map_metadata 0:s:0 out.mp3 +@end example + +To do the reverse, i.e. copy global metadata to all audio streams: +@example +ffmpeg -i in.mkv -map_metadata:s:a 0:g out.mkv +@end example +Note that simple @code{0} would work as well in this example, since global +metadata is assumed by default. + +@item -map_chapters @var{input_file_index} (@emph{output}) +Copy chapters from input file with index @var{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. +@item -debug @var{category} +Print specific debug info. +@var{category} is a number or a string containing one of the following values: +@table @samp +@item bitstream +@item buffers +picture buffer allocations +@item bugs +@item dct_coeff +@item er +error recognition +@item mb_type +macroblock (MB) type +@item mmco +memory management control operations (H.264) +@item mv +motion vector +@item pict +picture info +@item pts +@item qp +per-block quantization parameter (QP) +@item rc +rate control +@item skip +@item startcode +@item thread_ops +threading operations +@item vis_mb_type +visualize block types +@item vis_qp +visualize quantization parameter (QP), lower QP are tinted greener +@end table +@item -benchmark (@emph{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. +@item -benchmark_all (@emph{global}) +Show benchmarking information during the encode. +Shows CPU time used in various steps (audio/video encode/decode). +@item -timelimit @var{duration} (@emph{global}) +Exit after ffmpeg has been running for @var{duration} seconds. +@item -dump (@emph{global}) +Dump each input packet to stderr. +@item -hex (@emph{global}) +When dumping packets, also dump the payload. +@item -re (@emph{input}) +Read input at native frame rate. Mainly used to simulate a grab device. +By default @command{ffmpeg} attempts to read the input(s) as fast as possible. +This option will slow down the reading of the input(s) to the native frame rate +of the input(s). It is useful for real-time output (e.g. live streaming). If +your input(s) is coming from some other live streaming source (through HTTP or +UDP for example) the server might already be in real-time, thus the option will +likely not be required. On the other hand, this is meaningful if your input(s) +is a file you are trying to push in real-time. +@item -loop_input +Loop over the input stream. Currently it works only for image +streams. This option is used for automatic FFserver testing. +This option is deprecated, use -loop 1. +@item -loop_output @var{number_of_times} +Repeatedly loop output for formats that support looping such as animated GIF +(0 will loop the output infinitely). +This option is deprecated, use -loop. +@item -vsync @var{parameter} +Video sync method. +For compatibility reasons old values can be specified as numbers. +Newly added values will have to be specified as strings always. + +@table @option +@item 0, passthrough +Each frame is passed with its timestamp from the demuxer to the muxer. +@item 1, cfr +Frames will be duplicated and dropped to achieve exactly the requested +constant framerate. +@item 2, vfr +Frames are passed through with their timestamp or dropped so as to +prevent 2 frames from having the same timestamp. +@item drop +As passthrough but destroys all timestamps, making the muxer generate +fresh timestamps based on frame-rate. +@item -1, auto +Chooses between 1 and 2 depending on muxer capabilities. This is the +default method. +@end table + +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. + +@item -async @var{samples_per_second} +Audio sync method. "Stretches/squeezes" the audio stream to match the timestamps, +the parameter is the maximum samples per second by which the audio is changed. +-async 1 is a special case where only the start of the audio stream is corrected +without any later correction. +This option has been deprecated. Use the @code{asyncts} audio filter instead. +@item -copyts +Copy timestamps from input to output. +@item -copytb @var{mode} +Specify how to set the encoder timebase when stream copying. @var{mode} is an +integer numeric value, and can assume one of the following values: + +@table @option +@item 1 +Use the demuxer timebase. + +The time base is copied to the output encoder from the corresponding input +demuxer. This is sometimes required to avoid non monotonically increasing +timestamps when copying video streams with variable frame rate. + +@item 0 +Use the decoder timebase. + +The time base is copied to the output encoder from the corresponding input +decoder. + +@item -1 +Try to make the choice automatically, in order to generate a sane output. +@end table + +Default value is -1. + +@item -shortest +Finish encoding when the shortest input stream ends. +@item -dts_delta_threshold +Timestamp discontinuity delta threshold. +@item -muxdelay @var{seconds} (@emph{input}) +Set the maximum demux-decode delay. +@item -muxpreload @var{seconds} (@emph{input}) +Set the initial demux-decode delay. +@item -streamid @var{output-stream-index}:@var{new-value} (@emph{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: +@example +ffmpeg -i infile -streamid 0:33 -streamid 1:36 out.ts +@end example + +@item -bsf[:@var{stream_specifier}] @var{bitstream_filters} (@emph{output,per-stream}) +Set bitstream filters for matching streams. @var{bistream_filters} is +a comma-separated list of bitstream filters. Use the @code{-bsfs} option +to get the list of bitstream filters. +@example +ffmpeg -i h264.mp4 -c:v copy -bsf:v h264_mp4toannexb -an out.h264 +@end example +@example +ffmpeg -i file.mov -an -vn -bsf:s mov2textsub -c:s copy -f rawvideo sub.txt +@end example + +@item -tag[:@var{stream_specifier}] @var{codec_tag} (@emph{per-stream}) +Force a tag/fourcc for matching streams. + +@item -timecode @var{hh}:@var{mm}:@var{ss}SEP@var{ff} +Specify Timecode for writing. @var{SEP} is ':' for non drop timecode and ';' +(or '.') for drop. +@example +ffmpeg -i input.mpg -timecode 01:02:03.04 -r 30000/1001 -s ntsc output.mpg +@end example + +@item -filter_complex @var{filtergraph} (@emph{global}) +Define a complex filter graph, i.e. one with arbitrary number of inputs and/or +outputs. For simple graphs -- those with one input and one output of the same +type -- see the @option{-filter} options. @var{filtergraph} is a description of +the filter graph, as described in @ref{Filtergraph syntax}. + +Input link labels must refer to input streams using the +@code{[file_index:stream_specifier]} syntax (i.e. the same as @option{-map} +uses). If @var{stream_specifier} matches multiple streams, the first one will be +used. An unlabeled input will be connected to the first unused input stream of +the matching type. + +Output link labels are referred to with @option{-map}. Unlabeled outputs are +added to the first output file. + +For example, to overlay an image over video +@example +ffmpeg -i video.mkv -i image.png -filter_complex '[0:v][1:v]overlay[out]' -map +'[out]' out.mkv +@end example +Here @code{[0:v]} refers to the first video stream in the first input file, +which is linked to the first (main) input of the overlay filter. Similarly the +first video stream in the second input is linked to the second (overlay) input +of overlay. + +Assuming there is only one video stream in each input file, we can omit input +labels, so the above is equivalent to +@example +ffmpeg -i video.mkv -i image.png -filter_complex 'overlay[out]' -map +'[out]' out.mkv +@end example + +Furthermore we can omit the output label and the single output from the filter +graph will be added to the output file automatically, so we can simply write +@example +ffmpeg -i video.mkv -i image.png -filter_complex 'overlay' out.mkv +@end example +@end table + +As a special exception, you can use a bitmap subtitle stream as input: it +will be converted into a video with the same size as the largest video in +the file, or 720×576 if no video is present. Note that this is an +experimental and temporary solution. It will be removed once libavfilter has +proper support for subtitles. + +For example, to hardcode subtitles on top of a DVB-T recording stored in +MPEG-TS format, delaying the subtitles by 1 second: +@example +ffmpeg -i input.ts -filter_complex \ + '[#0x2ef] setpts=PTS+1/TB [sub] ; [#0x2d0] [sub] overlay' \ + -sn -map '#0x2dc' output.mkv +@end example +(0x2d0, 0x2dc and 0x2ef are the MPEG-TS PIDs of respectively the video, +audio and subtitles streams; 0:0, 0:3 and 0:7 would have worked too) + +@section Preset files +A preset file contains a sequence of @var{option}=@var{value} pairs, +one for each line, specifying a sequence of options which would be +awkward to specify on the command line. Lines starting with the hash +('#') character are ignored and are used to provide comments. Check +the @file{presets} directory in the FFmpeg source tree for examples. + +Preset files are specified with the @code{vpre}, @code{apre}, +@code{spre}, and @code{fpre} options. The @code{fpre} option takes the +filename of the preset instead of a preset name as input and can be +used for any kind of codec. For the @code{vpre}, @code{apre}, and +@code{spre} options, the options specified in a preset file are +applied to the currently selected codec of the same type as the preset +option. + +The argument passed to the @code{vpre}, @code{apre}, and @code{spre} +preset options identifies the preset file to use according to the +following rules: + +First ffmpeg searches for a file named @var{arg}.ffpreset in the +directories @file{$FFMPEG_DATADIR} (if set), and @file{$HOME/.ffmpeg}, and in +the datadir defined at configuration time (usually @file{PREFIX/share/ffmpeg}) +or in a @file{ffpresets} folder along the executable on win32, +in that order. For example, if the argument is @code{libvpx-1080p}, it will +search for the file @file{libvpx-1080p.ffpreset}. + +If no such file is found, then ffmpeg will search for a file named +@var{codec_name}-@var{arg}.ffpreset in the above-mentioned +directories, where @var{codec_name} is the name of the codec to which +the preset file options will be applied. For example, if you select +the video codec with @code{-vcodec libvpx} and use @code{-vpre 1080p}, +then it will search for the file @file{libvpx-1080p.ffpreset}. +@c man end OPTIONS + +@chapter Tips +@c man begin TIPS + +@itemize +@item +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: + +@example +ffmpeg -g 3 -r 3 -t 10 -b:v 50k -s qcif -f rv10 /tmp/b.rm +@end example + +@item +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. + +@item +If your computer is not fast enough, you can speed up the +compression at the expense of the compression ratio. You can use +'-me zero' to speed up motion estimation, and '-g 0' to disable +motion estimation completely (you have only I-frames, which means it +is about as good as JPEG compression). + +@item +To have very low audio bitrates, reduce the sampling frequency +(down to 22050 Hz for MPEG audio, 22050 or 11025 for AC-3). + +@item +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). + +@end itemize +@c man end TIPS + +@chapter Examples +@c man begin EXAMPLES + +@section Preset files + +A preset file contains a sequence of @var{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 +@file{presets} directory in the FFmpeg source tree for examples. + +Preset files are specified with the @code{pre} option, this option takes a +preset name as input. FFmpeg searches for a file named @var{preset_name}.avpreset in +the directories @file{$AVCONV_DATADIR} (if set), and @file{$HOME/.ffmpeg}, and in +the data directory defined at configuration time (usually @file{$PREFIX/share/ffmpeg}) +in that order. For example, if the argument is @code{libx264-max}, it will +search for the file @file{libx264-max.avpreset}. + +@section Video and Audio grabbing + +If you specify the input format and device then ffmpeg can grab video +and audio directly. + +@example +ffmpeg -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg +@end example + +Or with an ALSA audio source (mono input, card id 1) instead of OSS: +@example +ffmpeg -f alsa -ac 1 -i hw:1 -f video4linux2 -i /dev/video0 /tmp/out.mpg +@end example + +Note that you must activate the right video source and channel before +launching ffmpeg with any TV viewer such as +@uref{http://linux.bytesex.org/xawtv/, xawtv} by Gerd Knorr. You also +have to set the audio recording levels correctly with a +standard mixer. + +@section X11 grabbing + +Grab the X11 display with ffmpeg via + +@example +ffmpeg -f x11grab -s cif -r 25 -i :0.0 /tmp/out.mpg +@end example + +0.0 is display.screen number of your X11 server, same as +the DISPLAY environment variable. + +@example +ffmpeg -f x11grab -s cif -r 25 -i :0.0+10,20 /tmp/out.mpg +@end example + +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. + +@section Video and Audio file format conversion + +Any supported file format and protocol can serve as input to ffmpeg: + +Examples: +@itemize +@item +You can use YUV files as input: + +@example +ffmpeg -i /tmp/test%d.Y /tmp/out.mpg +@end example + +It will use the files: +@example +/tmp/test0.Y, /tmp/test0.U, /tmp/test0.V, +/tmp/test1.Y, /tmp/test1.U, /tmp/test1.V, etc... +@end example + +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 @option{-s} option +if ffmpeg cannot guess it. + +@item +You can input from a raw YUV420P file: + +@example +ffmpeg -i /tmp/test.yuv /tmp/out.avi +@end example + +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. + +@item +You can output to a raw YUV420P file: + +@example +ffmpeg -i mydivx.avi hugefile.yuv +@end example + +@item +You can set several input files and output files: + +@example +ffmpeg -i /tmp/a.wav -s 640x480 -i /tmp/a.yuv /tmp/a.mpg +@end example + +Converts the audio file a.wav and the raw YUV video file a.yuv +to MPEG file a.mpg. + +@item +You can also do audio and video conversions at the same time: + +@example +ffmpeg -i /tmp/a.wav -ar 22050 /tmp/a.mp2 +@end example + +Converts a.wav to MPEG audio at 22050 Hz sample rate. + +@item +You can encode to several formats at the same time and define a +mapping from input stream to output streams: + +@example +ffmpeg -i /tmp/a.wav -map 0:a -b:a 64k /tmp/a.mp2 -map 0:a -b:a 128k /tmp/b.mp2 +@end example + +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. + +@item +You can transcode decrypted VOBs: + +@example +ffmpeg -i snatch_1.vob -f avi -c:v mpeg4 -b:v 800k -g 300 -bf 2 -c:a libmp3lame -b:a 128k snatch.avi +@end example + +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 @code{--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 @code{ffmpeg -formats}. + +@item +You can extract images from a video, or create a video from many images: + +For extracting images from a video: +@example +ffmpeg -i foo.avi -r 1 -s WxH -f image2 foo-%03d.jpeg +@end example + +This will extract one video frame per second from the video and will +output them in files named @file{foo-001.jpeg}, @file{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: +@example +ffmpeg -f image2 -i foo-%03d.jpeg -r 12 -s WxH foo.avi +@end example + +The syntax @code{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. + +When importing an image sequence, -i also supports expanding shell-like +wildcard patterns (globbing) internally. To lower the chance of interfering +with your actual file names and the shell's glob expansion, you are required +to activate glob meta characters by prefixing them with a single @code{%} +character, like in @code{foo-%*.jpeg}, @code{foo-%?%?%?.jpeg} or +@code{foo-00%[234%]%*.jpeg}. +If your filename actually contains a character sequence of a @code{%} character +followed by a glob character, you must double the @code{%} character to escape +it. Imagine your files begin with @code{%?-foo-}, then you could use a glob +pattern like @code{%%?-foo-%*.jpeg}. For input patterns that could be both a +printf or a glob pattern, ffmpeg will assume it is a glob pattern. + +@item +You can put many streams of the same type in the output: + +@example +ffmpeg -i test1.avi -i test2.avi -map 0.3 -map 0.2 -map 0.1 -map 0.0 -c copy test12.nut +@end example + +The resulting output file @file{test12.avi} will contain first four streams from +the input file in reverse order. + +@item +To force CBR video output: +@example +ffmpeg -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v +@end example + +@item +The four options lmin, lmax, mblmin and mblmax use 'lambda' units, +but you may use the QP2LAMBDA constant to easily convert from 'q' units: +@example +ffmpeg -i src.ext -lmax 21*QP2LAMBDA dst.ext +@end example + +@end itemize +@c man end EXAMPLES + +@include syntax.texi +@include eval.texi +@include decoders.texi +@include encoders.texi +@include demuxers.texi +@include muxers.texi +@include indevs.texi +@include outdevs.texi +@include protocols.texi +@include bitstream_filters.texi +@include filters.texi +@include metadata.texi + +@ignore + +@setfilename ffmpeg +@settitle ffmpeg video converter + +@c man begin SEEALSO +ffplay(1), ffprobe(1), ffserver(1) and the FFmpeg HTML documentation +@c man end + +@c man begin AUTHORS +See git history +@c man end + +@end ignore + +@bye |