[mythtv] A/V diverged by +/-30 frames, extending frame to keep audio in sync

Lincoln Dale ltd at interlink.com.au
Tue Aug 30 00:25:33 UTC 2005


i have a bunch of recordings which seemingly hit something like this. 
the trigger point seems is somewhat random - but for the most part it 
has been about 90+ minutes into a 2 hour recording after which a/v sync 
gets way out of whack (and continues to get more out of sync the longer 
it goes on).

i thought it was something to do with mplayer .nuv patches (i use an 
xbox as a frontend where i have seen this) ..

i assume it has nothing to do with the length/time of the individual 
show that is being recorded, but rather that a "pts wrap" will occur 
sometime in a given mpeg2 stream (every 13 or 26 hours if i understand 
mpeg2 pts values correctly).

i presume we can add a fix into the demux code also to deal with this 
for previously transcoded streams also?  i.e. handle the wrap better?



Mark Spieth wrote:
> This is almost certainly a pts wrap effect.
> This assumes you have a mpeg2 recording which hasnt been transcoded.
> When it gets in this mode,
> use menu, select audiosync, press 0 or 1 (forget which) to do a fake resync.
> or apply this patch and see. If you have transcoded the patch wont do
> anything for you for the recording you have but will prevent this from
> happening in the future..
> cheers
> mark
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