[FFmpeg-devel] [PATCH] av_get_delay

Michael Niedermayer michaelni at gmx.at
Thu Jun 30 15:36:30 CEST 2011

On Thu, Jun 30, 2011 at 09:22:04AM -0400, Mike Scheutzow wrote:
> Michael Niedermayer wrote:
>>>> This doesnt seem to work very well for example when you have:
>>>> a slideshow with commentary, the delay from the video stream could
>>>> make quite big jumps an be constant between them. It might be
>>>> better to add the remaining duration of the currently displayed frame
>>>> in there or something
> This is a very different use case than the original proposal was meant  
> to solve, which I understood as pre-skewing uncompressed output samples  
> to improve lip sync.

you seem to missunderstand this somehow.
when you have 2 streams, 2 muxers, one only video and one only audio
and you want to sync them but the video muxer tells you as delay
only 0seconds or 30seconds you wont get sync better than 30seconds and
thats really not good for a slideshow of lets say pictures in a museum
that are being commented.

of course if your video display "muxer" displayes exactly based on
wallclock pts then you know the delay by looking at the pts and the

> It's clever to re-use the mux api for libavdevices, but I don't see much  
> muxing going on there.
> Maybe a more specific function name would reduce this confusion e.g.  
> estimate_presentation_delay().

One question is if it should also be intended for realtime streaming
like lets say for a video conference.
if yes, then actual muxing might happen and the interleave delay
becomes relevant

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Republics decline into democracies and democracies degenerate into
despotisms. -- Aristotle
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