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author | Nicolas George <nicolas.george@normalesup.org> | 2012-07-17 03:05:05 +0400 |
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committer | Nicolas George <nicolas.george@normalesup.org> | 2012-07-23 13:34:20 +0400 |
commit | be33da9a1d23f4770f6f1e01157f601ac6453b13 (patch) | |
tree | 5b085f972aea5b79fcf3d2104b3295483f8ae2dc /doc/filters.texi | |
parent | 1cadab602343c4f577d2710a43bc66fde5a0d20b (diff) |
lavfi: add concat filter.
Diffstat (limited to 'doc/filters.texi')
-rw-r--r-- | doc/filters.texi | 75 |
1 files changed, 75 insertions, 0 deletions
diff --git a/doc/filters.texi b/doc/filters.texi index 2b5cc875f5..8ffe703bce 100644 --- a/doc/filters.texi +++ b/doc/filters.texi @@ -4013,6 +4013,81 @@ tools. Below is a description of the currently available transmedia filters. +@section concat + +Concatenate audio and video streams, joining them together one after the +other. + +The filter works on segments of synchronized video and audio streams. All +segments must have the same number of streams of each type, and that will +also be the number of streams at output. + +The filter accepts the following named parameters: +@table @option + +@item n +Set the number of segments. Default is 2. + +@item v +Set the number of output video streams, that is also the number of video +streams in each segment. Default is 1. + +@item a +Set the number of output audio streams, that is also the number of video +streams in each segment. Default is 0. + +@end table + +The filter has @var{v}+@var{a} outputs: first @var{v} video outputs, then +@var{a} audio outputs. + +There are @var{n}×(@var{v}+@var{a}) inputs: first the inputs for the first +segment, in the same order as the outputs, then the inputs for the second +segment, etc. + +Related streams do not always have exactly the same duration, for various +reasons including codec frame size or sloppy authoring. For that reason, +related synchronized streams (e.g. a video and its audio track) should be +concatenated at once. The concat filter will use the duration of the longest +stream in each segment (except the last one), and if necessary pad shorter +audio streams with silence. + +For this filter to work correctly, all segments must start at timestamp 0. + +All corresponding streams must have the same parameters in all segments; the +filtering system will automatically select a common pixel format for video +streams, and a common sample format, sample rate and channel layout for +audio streams, but other settings, such as resolution, must be converted +explicitly by the user. + +Different frame rates are acceptable but will result in variable frame rate +at output; be sure to configure the output file to handle it. + +Examples: +@itemize +@item +Concatenate an opening, an episode and an ending, all in bilingual version +(video in stream 0, audio in streams 1 and 2): +@example +ffmpeg -i opening.mkv -i episode.mkv -i ending.mkv -filter_complex \ + '[0:0] [0:1] [0:2] [1:0] [1:1] [1:2] [2:0] [2:1] [2:2] + concat=n=3:v=1:a=2 [v] [a1] [a2]' \ + -map '[v]' -map '[a1]' -map '[a2]' output.mkv +@end example + +@item +Concatenate two parts, handling audio and video separately, using the +(a)movie sources, and adjusting the resolution: +@example +movie=part1.mp4, scale=512:288 [v1] ; amovie=part1.mp4 [a1] ; +movie=part2.mp4, scale=512:288 [v2] ; amovie=part2.mp4 [a2] ; +[v1] [v2] concat [outv] ; [a1] [a2] concat=v=0:a=1 [outa] +@end example +Note that a desync will happen at the stitch if the audio and video streams +do not have exactly the same duration in the first file. + +@end itemize + @section showwaves Convert input audio to a video output, representing the samples waves. |