[vlc-devel] [PATCH] Discontinuities in source scr/pts/ dts break transcoding for dvdread -> mp4

Rémi Denis-Courmont remi at remlab.net
Sat Oct 17 09:34:21 CEST 2009

Christopher Key wrote:
> Hello,
> I recently ran into problems trying to transcode dvds to mp4 format. 
> Following any discontinuity in the scr (e.g. layer break, or skip over
> unreadable sectors), I would lose the audio in the output.  What was
> happening was that the discontinuity was causing the dts timestamps on
> packets to jump backwards*.  As the muxer uses two fifos (audio and
> video) and pulls in whichever of the packets has the lowest dts, a jump
> back in time causes problems.  Imagine two FIFOs, with packets with the
> following dts timeamps:
> {...,6,4,2,98,96} and {...,5,3,1,99,97}

Shouldn't this be fixed with a roll-over carry counter rather than by 
trying to autodetect discontinuities?

Rémi Denis-Courmont

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