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1112 lines
40 KiB
\input texinfo @c -*- texinfo -*- |
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@settitle avconv Documentation |
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@titlepage |
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@center @titlefont{avconv Documentation} |
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@end titlepage |
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@top |
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@contents |
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@chapter Synopsis |
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The generic syntax is: |
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@example |
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@c man begin SYNOPSIS |
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avconv [global options] [[infile options][@option{-i} @var{infile}]]... @{[outfile options] @var{outfile}@}... |
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@c man end |
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@end example |
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@chapter Description |
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@c man begin DESCRIPTION |
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avconv is a very fast video and audio converter that can also grab from |
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a live audio/video source. It can also convert between arbitrary sample |
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rates and resize video on the fly with a high quality polyphase filter. |
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avconv reads from an arbitrary number of input "files" (which can be regular |
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files, pipes, network streams, grabbing devices, etc.), specified by the |
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@code{-i} option, and writes to an arbitrary number of output "files", which are |
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specified by a plain output filename. Anything found on the command line which |
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cannot be interpreted as an option is considered to be an output filename. |
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Each input or output file can in principle contain any number of streams of |
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different types (video/audio/subtitle/attachment/data). Allowed number and/or |
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types of streams can be limited by the container format. Selecting, which |
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streams from which inputs go into output, is done either automatically or with |
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the @code{-map} option (see the Stream selection chapter). |
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To refer to input files in options, you must use their indices (0-based). E.g. |
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the first input file is @code{0}, the second is @code{1} etc. Similarly, streams |
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within a file are referred to by their indices. E.g. @code{2:3} refers to the |
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fourth stream in the third input file. See also the Stream specifiers chapter. |
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As a general rule, options are applied to the next specified |
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file. Therefore, order is important, and you can have the same |
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option on the command line multiple times. Each occurrence is |
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then applied to the next input or output file. |
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Exceptions from this rule are the global options (e.g. verbosity level), |
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which should be specified first. |
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Do not mix input and output files -- first specify all input files, then all |
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output files. Also do not mix options which belong to different files. All |
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options apply ONLY to the next input or output file and are reset between files. |
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@itemize |
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@item |
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To set the video bitrate of the output file to 64kbit/s: |
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@example |
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avconv -i input.avi -b 64k output.avi |
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@end example |
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@item |
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To force the frame rate of the output file to 24 fps: |
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@example |
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avconv -i input.avi -r 24 output.avi |
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@end example |
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@item |
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To force the frame rate of the input file (valid for raw formats only) |
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to 1 fps and the frame rate of the output file to 24 fps: |
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@example |
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avconv -r 1 -i input.m2v -r 24 output.avi |
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@end example |
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@end itemize |
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The format option may be needed for raw input files. |
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@c man end DESCRIPTION |
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@chapter Detailed description |
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@c man begin DETAILED DESCRIPTION |
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The transcoding process in @command{avconv} for each output can be described by |
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the following diagram: |
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@example |
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_______ ______________ _________ ______________ ________ |
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| | | | | | | | | | |
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| input | demuxer | encoded data | decoder | decoded | encoder | encoded data | muxer | output | |
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| file | ---------> | packets | ---------> | frames | ---------> | packets | -------> | file | |
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|_______| |______________| |_________| |______________| |________| |
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@end example |
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@command{avconv} calls the libavformat library (containing demuxers) to read |
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input files and get packets containing encoded data from them. When there are |
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multiple input files, @command{avconv} tries to keep them synchronized by |
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tracking lowest timestamp on any active input stream. |
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Encoded packets are then passed to the decoder (unless streamcopy is selected |
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for the stream, see further for a description). The decoder produces |
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uncompressed frames (raw video/PCM audio/...) which can be processed further by |
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filtering (see next section). After filtering the frames are passed to the |
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encoder, which encodes them and outputs encoded packets again. Finally those are |
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passed to the muxer, which writes the encoded packets to the output file. |
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@section Filtering |
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Before encoding, @command{avconv} can process raw audio and video frames using |
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filters from the libavfilter library. Several chained filters form a filter |
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graph. @command{avconv} distinguishes between two types of filtergraphs - |
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simple and complex. |
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@subsection Simple filtergraphs |
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Simple filtergraphs are those that have exactly one input and output, both of |
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the same type. In the above diagram they can be represented by simply inserting |
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an additional step between decoding and encoding: |
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@example |
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_________ __________ ______________ |
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| | | | | | |
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| decoded | simple filtergraph | filtered | encoder | encoded data | |
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| frames | -------------------> | frames | ---------> | packets | |
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|_________| |__________| |______________| |
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@end example |
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Simple filtergraphs are configured with the per-stream @option{-filter} option |
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(with @option{-vf} and @option{-af} aliases for video and audio respectively). |
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A simple filtergraph for video can look for example like this: |
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@example |
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_______ _____________ _______ _____ ________ |
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| | | | | | | | | | |
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| input | ---> | deinterlace | ---> | scale | ---> | fps | ---> | output | |
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|_______| |_____________| |_______| |_____| |________| |
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@end example |
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Note that some filters change frame properties but not frame contents. E.g. the |
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@code{fps} filter in the example above changes number of frames, but does not |
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touch the frame contents. Another example is the @code{setpts} filter, which |
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only sets timestamps and otherwise passes the frames unchanged. |
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@subsection Complex filtergraphs |
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Complex filtergraphs are those which cannot be described as simply a linear |
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processing chain applied to one stream. This is the case e.g. when the graph has |
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more than one input and/or output, or when output stream type is different from |
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input. They can be represented with the following diagram: |
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@example |
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_________ |
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| | |
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| input 0 |\ __________ |
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|_________| \ | | |
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\ _________ /| output 0 | |
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\ | | / |__________| |
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_________ \| complex | / |
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| | | |/ |
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| input 1 |---->| filter |\ |
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|_________| | | \ __________ |
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/| graph | \ | | |
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/ | | \| output 1 | |
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_________ / |_________| |__________| |
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| | / |
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| input 2 |/ |
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|_________| |
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@end example |
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Complex filtergraphs are configured with the @option{-filter_complex} option. |
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Note that this option is global, since a complex filtergraph by its nature |
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cannot be unambiguously associated with a single stream or file. |
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A trivial example of a complex filtergraph is the @code{overlay} filter, which |
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has two video inputs and one video output, containing one video overlaid on top |
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of the other. Its audio counterpart is the @code{amix} filter. |
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@section Stream copy |
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Stream copy is a mode selected by supplying the @code{copy} parameter to the |
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@option{-codec} option. It makes @command{avconv} omit the decoding and encoding |
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step for the specified stream, so it does only demuxing and muxing. It is useful |
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for changing the container format or modifying container-level metadata. The |
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diagram above will in this case simplify to this: |
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@example |
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_______ ______________ ________ |
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| | | | | | |
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| input | demuxer | encoded data | muxer | output | |
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| file | ---------> | packets | -------> | file | |
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|_______| |______________| |________| |
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@end example |
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Since there is no decoding or encoding, it is very fast and there is no quality |
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loss. However it might not work in some cases because of many factors. Applying |
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filters is obviously also impossible, since filters work on uncompressed data. |
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@c man end DETAILED DESCRIPTION |
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@chapter Stream selection |
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@c man begin STREAM SELECTION |
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By default avconv tries to pick the "best" stream of each type present in input |
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files and add them to each output file. For video, this means the highest |
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resolution, for audio the highest channel count. For subtitle it's simply the |
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first subtitle stream. |
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You can disable some of those defaults by using @code{-vn/-an/-sn} options. For |
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full manual control, use the @code{-map} option, which disables the defaults just |
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described. |
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@c man end STREAM SELECTION |
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@chapter Options |
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@c man begin OPTIONS |
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@include avtools-common-opts.texi |
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@section Main options |
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@table @option |
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@item -f @var{fmt} (@emph{input/output}) |
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Force input or output file format. The format is normally autodetected for input |
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files and guessed from file extension for output files, so this option is not |
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needed in most cases. |
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@item -i @var{filename} (@emph{input}) |
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input file name |
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@item -y (@emph{global}) |
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Overwrite output files without asking. |
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@item -n (@emph{global}) |
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Immediately exit when output files already exist. |
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@item -c[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream}) |
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@itemx -codec[:@var{stream_specifier}] @var{codec} (@emph{input/output,per-stream}) |
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Select an encoder (when used before an output file) or a decoder (when used |
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before an input file) for one or more streams. @var{codec} is the name of a |
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decoder/encoder or a special value @code{copy} (output only) to indicate that |
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the stream is not to be reencoded. |
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For example |
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@example |
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avconv -i INPUT -map 0 -c:v libx264 -c:a copy OUTPUT |
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@end example |
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encodes all video streams with libx264 and copies all audio streams. |
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For each stream, the last matching @code{c} option is applied, so |
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@example |
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avconv -i INPUT -map 0 -c copy -c:v:1 libx264 -c:a:137 libvorbis OUTPUT |
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@end example |
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will copy all the streams except the second video, which will be encoded with |
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libx264, and the 138th audio, which will be encoded with libvorbis. |
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@item -t @var{duration} (@emph{output}) |
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Stop writing the output after its duration reaches @var{duration}. |
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@var{duration} may be a number in seconds, or in @code{hh:mm:ss[.xxx]} form. |
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@item -fs @var{limit_size} (@emph{output}) |
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Set the file size limit. |
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@item -ss @var{position} (@emph{input/output}) |
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When used as an input option (before @code{-i}), seeks in this input file to |
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@var{position}. Note the in most formats it is not possible to seek exactly, so |
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@command{avconv} will seek to the closest seek point before @var{position}. |
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When transcoding and @option{-accurate_seek} is enabled (the default), this |
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extra segment between the seek point and @var{position} will be decoded and |
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discarded. When doing stream copy or when @option{-noaccurate_seek} is used, it |
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will be preserved. |
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When used as an output option (before an output filename), decodes but discards |
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input until the timestamps reach @var{position}. |
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@var{position} may be either in seconds or in @code{hh:mm:ss[.xxx]} form. |
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@item -itsoffset @var{offset} (@emph{input}) |
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Set the input time offset in seconds. |
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@code{[-]hh:mm:ss[.xxx]} syntax is also supported. |
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The offset is added to the timestamps of the input files. |
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Specifying a positive offset means that the corresponding |
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streams are delayed by @var{offset} seconds. |
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@item -metadata[:metadata_specifier] @var{key}=@var{value} (@emph{output,per-metadata}) |
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Set a metadata key/value pair. |
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An optional @var{metadata_specifier} may be given to set metadata |
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on streams or chapters. See @code{-map_metadata} documentation for |
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details. |
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This option overrides metadata set with @code{-map_metadata}. It is |
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also possible to delete metadata by using an empty value. |
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For example, for setting the title in the output file: |
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@example |
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avconv -i in.avi -metadata title="my title" out.flv |
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@end example |
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To set the language of the first audio stream: |
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@example |
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avconv -i INPUT -metadata:s:a:0 language=eng OUTPUT |
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@end example |
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@item -target @var{type} (@emph{output}) |
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Specify target file type (@code{vcd}, @code{svcd}, @code{dvd}, @code{dv}, |
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@code{dv50}). @var{type} may be prefixed with @code{pal-}, @code{ntsc-} or |
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@code{film-} to use the corresponding standard. All the format options |
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(bitrate, codecs, buffer sizes) are then set automatically. You can just type: |
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@example |
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avconv -i myfile.avi -target vcd /tmp/vcd.mpg |
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@end example |
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Nevertheless you can specify additional options as long as you know |
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they do not conflict with the standard, as in: |
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@example |
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avconv -i myfile.avi -target vcd -bf 2 /tmp/vcd.mpg |
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@end example |
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@item -dframes @var{number} (@emph{output}) |
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Set the number of data frames to record. This is an alias for @code{-frames:d}. |
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@item -frames[:@var{stream_specifier}] @var{framecount} (@emph{output,per-stream}) |
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Stop writing to the stream after @var{framecount} frames. |
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@item -q[:@var{stream_specifier}] @var{q} (@emph{output,per-stream}) |
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@itemx -qscale[:@var{stream_specifier}] @var{q} (@emph{output,per-stream}) |
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Use fixed quality scale (VBR). The meaning of @var{q} is |
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codec-dependent. |
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@item -filter[:@var{stream_specifier}] @var{filter_graph} (@emph{output,per-stream}) |
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@var{filter_graph} is a description of the filter graph to apply to |
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the stream. Use @code{-filters} to show all the available filters |
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(including also sources and sinks). |
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See also the @option{-filter_complex} option if you want to create filter graphs |
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with multiple inputs and/or outputs. |
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@item -filter_script[:@var{stream_specifier}] @var{filename} (@emph{output,per-stream}) |
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This option is similar to @option{-filter}, the only difference is that its |
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argument is the name of the file from which a filtergraph description is to be |
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read. |
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@item -pre[:@var{stream_specifier}] @var{preset_name} (@emph{output,per-stream}) |
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Specify the preset for matching stream(s). |
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@item -stats (@emph{global}) |
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Print encoding progress/statistics. On by default. |
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@item -attach @var{filename} (@emph{output}) |
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Add an attachment to the output file. This is supported by a few formats |
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like Matroska for e.g. fonts used in rendering subtitles. Attachments |
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are implemented as a specific type of stream, so this option will add |
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a new stream to the file. It is then possible to use per-stream options |
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on this stream in the usual way. Attachment streams created with this |
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option will be created after all the other streams (i.e. those created |
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with @code{-map} or automatic mappings). |
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Note that for Matroska you also have to set the mimetype metadata tag: |
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@example |
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avconv -i INPUT -attach DejaVuSans.ttf -metadata:s:2 mimetype=application/x-truetype-font out.mkv |
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@end example |
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(assuming that the attachment stream will be third in the output file). |
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@item -dump_attachment[:@var{stream_specifier}] @var{filename} (@emph{input,per-stream}) |
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Extract the matching attachment stream into a file named @var{filename}. If |
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@var{filename} is empty, then the value of the @code{filename} metadata tag |
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will be used. |
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E.g. to extract the first attachment to a file named 'out.ttf': |
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@example |
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avconv -dump_attachment:t:0 out.ttf INPUT |
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@end example |
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To extract all attachments to files determined by the @code{filename} tag: |
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@example |
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avconv -dump_attachment:t "" INPUT |
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@end example |
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Technical note -- attachments are implemented as codec extradata, so this |
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option can actually be used to extract extradata from any stream, not just |
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attachments. |
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@end table |
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@section Video Options |
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@table @option |
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@item -vframes @var{number} (@emph{output}) |
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Set the number of video frames to record. This is an alias for @code{-frames:v}. |
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@item -r[:@var{stream_specifier}] @var{fps} (@emph{input/output,per-stream}) |
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Set frame rate (Hz value, fraction or abbreviation). |
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As an input option, ignore any timestamps stored in the file and instead |
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generate timestamps assuming constant frame rate @var{fps}. |
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As an output option, duplicate or drop input frames to achieve constant output |
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frame rate @var{fps} (note that this actually causes the @code{fps} filter to be |
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inserted to the end of the corresponding filtergraph). |
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@item -s[:@var{stream_specifier}] @var{size} (@emph{input/output,per-stream}) |
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Set frame size. |
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As an input option, this is a shortcut for the @option{video_size} private |
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option, recognized by some demuxers for which the frame size is either not |
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stored in the file or is configurable -- e.g. raw video or video grabbers. |
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As an output option, this inserts the @code{scale} video filter to the |
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@emph{end} of the corresponding filtergraph. Please use the @code{scale} filter |
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directly to insert it at the beginning or some other place. |
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The format is @samp{wxh} (default - same as source). The following |
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abbreviations are recognized: |
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@table @samp |
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@item sqcif |
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128x96 |
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@item qcif |
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176x144 |
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@item cif |
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352x288 |
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@item 4cif |
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704x576 |
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@item 16cif |
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1408x1152 |
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@item qqvga |
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160x120 |
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@item qvga |
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320x240 |
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@item vga |
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640x480 |
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@item svga |
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800x600 |
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@item xga |
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1024x768 |
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@item uxga |
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1600x1200 |
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@item qxga |
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2048x1536 |
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@item sxga |
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1280x1024 |
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@item qsxga |
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2560x2048 |
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@item hsxga |
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5120x4096 |
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@item wvga |
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852x480 |
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@item wxga |
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1366x768 |
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@item wsxga |
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1600x1024 |
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@item wuxga |
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1920x1200 |
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@item woxga |
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2560x1600 |
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@item wqsxga |
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3200x2048 |
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@item wquxga |
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3840x2400 |
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@item whsxga |
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6400x4096 |
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@item whuxga |
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7680x4800 |
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@item cga |
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320x200 |
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@item ega |
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640x350 |
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@item hd480 |
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852x480 |
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@item hd720 |
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1280x720 |
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@item hd1080 |
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1920x1080 |
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@end table |
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@item -aspect[:@var{stream_specifier}] @var{aspect} (@emph{output,per-stream}) |
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Set the video display aspect ratio specified by @var{aspect}. |
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@var{aspect} can be a floating point number string, or a string of the |
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form @var{num}:@var{den}, where @var{num} and @var{den} are the |
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numerator and denominator of the aspect ratio. For example "4:3", |
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"16:9", "1.3333", and "1.7777" are valid argument values. |
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@item -vn (@emph{output}) |
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Disable video recording. |
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@item -vcodec @var{codec} (@emph{output}) |
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Set the video codec. This is an alias for @code{-codec:v}. |
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@item -pass[:@var{stream_specifier}] @var{n} (@emph{output,per-stream}) |
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Select the pass number (1 or 2). It is used to do two-pass |
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video encoding. The statistics of the video are recorded in the first |
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pass into a log file (see also the option -passlogfile), |
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and in the second pass that log file is used to generate the video |
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at the exact requested bitrate. |
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On pass 1, you may just deactivate audio and set output to null, |
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examples for Windows and Unix: |
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@example |
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avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y NUL |
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avconv -i foo.mov -c:v libxvid -pass 1 -an -f rawvideo -y /dev/null |
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@end example |
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@item -passlogfile[:@var{stream_specifier}] @var{prefix} (@emph{output,per-stream}) |
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Set two-pass log file name prefix to @var{prefix}, the default file name |
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prefix is ``av2pass''. The complete file name will be |
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@file{PREFIX-N.log}, where N is a number specific to the output |
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stream. |
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@item -vf @var{filter_graph} (@emph{output}) |
|
@var{filter_graph} is a description of the filter graph to apply to |
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the input video. |
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Use the option "-filters" to show all the available filters (including |
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also sources and sinks). This is an alias for @code{-filter:v}. |
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@end table |
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@section Advanced Video Options |
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@table @option |
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@item -pix_fmt[:@var{stream_specifier}] @var{format} (@emph{input/output,per-stream}) |
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Set pixel format. Use @code{-pix_fmts} to show all the supported |
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pixel formats. |
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@item -sws_flags @var{flags} (@emph{input/output}) |
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Set SwScaler flags. |
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@item -vdt @var{n} |
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Discard threshold. |
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@item -rc_override[:@var{stream_specifier}] @var{override} (@emph{output,per-stream}) |
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rate control override for specific intervals |
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|
|
@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 -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}. |
|
@end table |
|
|
|
@section Subtitle options: |
|
|
|
@table @option |
|
@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. |
|
@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 |
|
avconv -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 |
|
avconv -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 |
|
avconv -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 |
|
avconv -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 |
|
avconv -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_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 |
|
avconv -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 |
|
avconv -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 |
|
Print specific debug info. |
|
@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 -timelimit @var{duration} (@emph{global}) |
|
Exit after avconv 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 |
|
or live input stream (e.g. when reading from a file). Should not be used |
|
with actual grab devices or live input streams (where it can cause packet |
|
loss). |
|
@item -vsync @var{parameter} |
|
Video sync method. |
|
|
|
@table @option |
|
@item passthrough |
|
Each frame is passed with its timestamp from the demuxer to the muxer. |
|
@item cfr |
|
Frames will be duplicated and dropped to achieve exactly the requested |
|
constant framerate. |
|
@item vfr |
|
Frames are passed through with their timestamp or dropped so as to |
|
prevent 2 frames from having the same timestamp. |
|
@item 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 |
|
Copy input stream time base from input to output when stream copying. |
|
@item -shortest (@emph{output}) |
|
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 |
|
avconv -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 |
|
avconv -i h264.mp4 -c:v copy -bsf:v h264_mp4toannexb -an out.h264 |
|
@end example |
|
@example |
|
avconv -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{output,per-stream}) |
|
Force a tag/fourcc for matching streams. |
|
|
|
@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. |
|
|
|
Note that with this option it is possible to use only lavfi sources without |
|
normal input files. |
|
|
|
For example, to overlay an image over video |
|
@example |
|
avconv -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 |
|
avconv -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 |
|
avconv -i video.mkv -i image.png -filter_complex 'overlay' out.mkv |
|
@end example |
|
|
|
To generate 5 seconds of pure red video using lavfi @code{color} source: |
|
@example |
|
avconv -filter_complex 'color=red' -t 5 out.mkv |
|
@end example |
|
|
|
@item -filter_complex_script @var{filename} (@emph{global}) |
|
This option is similar to @option{-filter_complex}, the only difference is that |
|
its argument is the name of the file from which a complex filtergraph |
|
description is to be read. |
|
|
|
@item -accurate_seek (@emph{input}) |
|
This option enables or disables accurate seeking in input files with the |
|
@option{-ss} option. It is enabled by default, so seeking is accurate when |
|
transcoding. Use @option{-noaccurate_seek} to disable it, which may be useful |
|
e.g. when copying some streams and transcoding the others. |
|
|
|
@end table |
|
@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 |
|
avconv -g 3 -r 3 -t 10 -b 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 Libav source tree for examples. |
|
|
|
Preset files are specified with the @code{pre} option, this option takes a |
|
preset name as input. Avconv searches for a file named @var{preset_name}.avpreset in |
|
the directories @file{$AVCONV_DATADIR} (if set), and @file{$HOME/.avconv}, and in |
|
the data directory defined at configuration time (usually @file{$PREFIX/share/avconv}) |
|
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 avconv can grab video |
|
and audio directly. |
|
|
|
@example |
|
avconv -f oss -i /dev/dsp -f video4linux2 -i /dev/video0 /tmp/out.mpg |
|
@end example |
|
|
|
Note that you must activate the right video source and channel before |
|
launching avconv 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 avconv via |
|
|
|
@example |
|
avconv -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 |
|
avconv -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 avconv: |
|
|
|
Examples: |
|
@itemize |
|
@item |
|
You can use YUV files as input: |
|
|
|
@example |
|
avconv -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 avconv cannot guess it. |
|
|
|
@item |
|
You can input from a raw YUV420P file: |
|
|
|
@example |
|
avconv -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 |
|
avconv -i mydivx.avi hugefile.yuv |
|
@end example |
|
|
|
@item |
|
You can set several input files and output files: |
|
|
|
@example |
|
avconv -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 |
|
avconv -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 |
|
avconv -i /tmp/a.wav -map 0:a -b 64k /tmp/a.mp2 -map 0:a -b 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 |
|
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 |
|
@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{avconv -formats}. |
|
|
|
@item |
|
You can extract images from a video, or create a video from many images: |
|
|
|
For extracting images from a video: |
|
@example |
|
avconv -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}, |
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etc. Images will be rescaled to fit the new WxH values. |
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If you want to extract just a limited number of frames, you can use the |
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above command in combination with the -vframes or -t option, or in |
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combination with -ss to start extracting from a certain point in time. |
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For creating a video from many images: |
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@example |
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avconv -f image2 -i foo-%03d.jpeg -r 12 -s WxH foo.avi |
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@end example |
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The syntax @code{foo-%03d.jpeg} specifies to use a decimal number |
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composed of three digits padded with zeroes to express the sequence |
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number. It is the same syntax supported by the C printf function, but |
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only formats accepting a normal integer are suitable. |
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@item |
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You can put many streams of the same type in the output: |
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|
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@example |
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avconv -i test1.avi -i test2.avi -map 0.3 -map 0.2 -map 0.1 -map 0.0 -c copy test12.nut |
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@end example |
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The resulting output file @file{test12.avi} will contain first four streams from |
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the input file in reverse order. |
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@item |
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To force CBR video output: |
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@example |
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avconv -i myfile.avi -b 4000k -minrate 4000k -maxrate 4000k -bufsize 1835k out.m2v |
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@end example |
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@item |
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The four options lmin, lmax, mblmin and mblmax use 'lambda' units, |
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but you may use the QP2LAMBDA constant to easily convert from 'q' units: |
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@example |
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avconv -i src.ext -lmax 21*QP2LAMBDA dst.ext |
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@end example |
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@end itemize |
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@c man end EXAMPLES |
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@include eval.texi |
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@include encoders.texi |
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@include demuxers.texi |
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@include muxers.texi |
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@include indevs.texi |
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@include outdevs.texi |
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@include protocols.texi |
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@include bitstream_filters.texi |
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@include filters.texi |
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@include metadata.texi |
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@ignore |
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@setfilename avconv |
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@settitle avconv video converter |
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|
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@c man begin SEEALSO |
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avplay(1), avprobe(1) and the Libav HTML documentation |
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@c man end |
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@c man begin AUTHORS |
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The Libav developers |
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@c man end |
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@end ignore |
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@bye
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