[FFmpeg-cvslog] r15206 - in trunk/libavformat: matroskadec.c matroskaenc.c

[Uoti Urpala]

On Fri, 2008-09-05 at 03:10 +0200, Michael Niedermayer wrote:
> convergence_duration of 10 means that in 10 timebase units from now the
> output of the decoder when started with this frame will match what it
> would have been when started from the very first frame.
> 
> that is if 5 minutes ago there was a subtitle that has a display duration
> of 7 min then convergence_duration could be 2min for the current
> subtitle packet because if we stat decoding now we will be missing this
> subtitle and thus output will differ for 2 min. Of course if this past

BTW how do you expect this to work in practice for subtitles (I assume
you do expect it could work in some case since subtitles are explicitly
mentioned in the documentation)? This is a field in a demuxer packet,
but typically there is no packet right after a seek where you could set
it. Do you expect the demuxer to generate a dummy packet whose only
meaningful information is the value of this field? Needing to
special-case such dummy packets in the receiver could cause other
problems.

I think it's not possible to set this with any currently used container
format unless you scan the stream in advance of the seek (maybe NUT was
supposed to support it directly)? And if you do scan it then caching the
needed subtitles to always allow correct playback immediately from the
seek position is probably a better solution.