[vdr] problem vdr-xine-0.7.3 plugin

Reinhard Nissl rnissl at gmx.de
Mon Apr 18 22:30:55 CEST 2005


Jouni Karvo wrote:

>  > To come back to your problem: when you read about demuxing you'll find 
>  > that there is a typical delta between audio and video of up to 700 ms 
>  > which corresponds to 63000 pts. So I thought the default WRAP_THRESHOLD 
>  > of 120000 pts would be ok to not trigger any false discontinuities. As 
>  > you wrote below, a larger value seems to fix your problem. Would you 
>  > please be so kind and try 150000 (= 5/3 seconds) and if this doesn't 
>  > solve the issue 180000 (= 2 seconds). As this value typically serves for 
>  > detecting a PTS wrap, it would also be ok to choose a really larger 
>  > value up to 2^31.
> I have now tried with 200000.  This runs pretty well, there is approx
> one pause of sound approx one second every 3-4 hours.  (VDR recovers
> and image is not affected).

If you run xine with --verbose=2, do you see a discontinuity reported at 
that time, maybe in conjunction with an audio jump?

> With 150000, it still runs.  Now the approx one second pause seems to
> happen once every 15-60min.  (and recovery is also working)
> So, it seems that there is some probability distribution of these
> deltas, and increasing WRAP_THRESHOLD reduces the probability that the
> delta is too large.
> Is there any upper limit of the possible delta values (less than this
> 2^31)?

I don't think so. It typically should detect wraps from about 2^33 - 1 
to about 0 and back.

> Is there any harm to have a really large value?  If not, then I guess
> it would be good to have a large value so as to make the problem
> probability small.

Well, you might try 900000 (= 10 seconds). Any jump below these value 
might then cause an audio jump of up to 10 seconds (= delay of up to 10 

Strange is, that such a shift between PTS of audio and video packets 
needs to be compensated by a buffer to synchronize them. A buffer of 
200000 / 90000 seconds still seems to be not large enough in your case. 
How does a set top box cope with that channel?

Dipl.-Inform. (FH) Reinhard Nissl
mailto:rnissl at gmx.de

More information about the vdr mailing list