[Ffmpeg-devel] [PATCH] sync output stream against any input stream (extension of map)

Michael Niedermayer michaelni
Thu May 26 10:59:38 CEST 2005


On Wednesday 25 May 2005 17:49, Wolfram Gloger wrote:
> Hi,
> Until sometime last year, audio streams were always the "master" in
> ffmpeg when it came to synchronization.
> Today, there is no master anymore and every output stream is "only"
> synched against its corresponding input.
> This is basically ok, because "-async" was introduced at the same time
> and works quite well to compensate drift in audio streams.  However,
> sometimes you can't or don't want to use "-async", eg. with "-acodec
> copy".  Then, it may still be acceptable to drop/dup video frames and
> you want to synchronize the video against a particular audio stream.
> The opposite is also conceivable: you don't want to mess with the
> video frame order at all ("-vsync 0" or "-vcodec copy") but still want
> to use "-async 50", for example.
> In those cases I think the appended patch is useful, and I think it is
> _necessary_ for output formats without timestams.  There are simply
> two additional (optional) arguments to "-map" specifying the input
> stream to sync against.



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