[vdr] FF card A/V sync suggestion

Udo Richter udo_richter at gmx.de
Sat Oct 28 20:56:52 CEST 2006

Udo Richter wrote:
> Tero Siironen wrote:
>> Here is a 3 minute clip from the episode of Lost I told earlier.
>> http://kotisivu.suomi.net/izero/lost.tar
>> 80MB file and played ok at least with VLC v 0.8.5. and MPlayer on OS X
> Demultiplexing with ProjectX throws 11649 of errors like this:
> !> error in pes_extension of pes-ID 0xE0 @ pos: 38780 (2048 / 14 / 15 / 
> true / false)
> pos is changing, the rest seems always the same.
> I then re-muxed the elementary streams and converted them back to VDR, 
> and the resulting video played fine again. So this issue seems to be 
> some problem on the PES packaging layer.

I've done some more analysis on the file using dvbsnoop and checked the 
PES packet timings. Audio frame packets are present every 24ms, video 
packets are present every 40ms. All packets are present, no packets 
dropped. So much for stacked frames, at least on the PES layer every 
frame is present.

In the stream, the audio packets are ahead of the video packets, on 
average by 470ms. (min: 137ms, max: 905ms.) This seems to be well inside 
the tolerance that the DVB driver can handle.

The only disturbance I've noticed is a slight jitter in the PTS values 
of the audio packets, they are sometimes off by +/- 1, thats 0.01ms. I 
don't know whether the driver ignores such slight offsets, but I guess 
it probably does, esp. since it seems to never sync anyway.



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