[vlc-devel] Re: VLC skips on "reduced" MPEG2-TS streams

Christophe Massiot massiot at via.ecp.fr
Wed Jan 17 15:18:49 CET 2007

On Wed, Jan 17, 2007, Derk-Jan Hartman wrote:

> >The timing problems disappear when I set --file-caching to 600 msec  
> >or above.
> >Such setting is not needed on any other MPEG2 stream we're using
> >(including HDTV ones).
> >
> >Any ideas about the reason - wrong stream? default 300 msec file- 
> >caching
> >too low? synchro bug? other?
> Interleaving of the A/V data wasn't done with the advised settings.  
> This is a bad stream, 300ms really should be enough.
> Meeuh ? Don't they advise something like 60ms max of interleaving  
> space ?

Indeed the delay between PCR and PTS is too low, and there is not enough
time from the moment when the packet enters the decoder until the moment
we're supposed to display it. Theoritically the minimum is 120 ms (one I
+ 2 B's), to which we add 300 ms, so even at the minimum we should have
time to decode the frames. I suppose the PTS's are in the past then.

AFAIK there is no specification for this value, at least not in MPEG.
Conventional broadcaster use a value of 500 ms between the PCR and the
next PTS.
Christophe Massiot.

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