[linux-dvb] Re: can't record some channels with vdr and a nova-s budget card.

[Johannes Stezenbach <js@convergence.de>]

Klaus Schmidinger wrote:
> Johannes Stezenbach wrote:
> > claas+linuxtv-dvb@jucs-kramkiste.de wrote:
> > 
> > > RTL was recorded without any errors.
> > >
> > > SAT1 was recorded with these errors:
> > >
> > > Oct 13 21:00:00 tvt1 vdr[795]: cTS2PES got 1403 TS errors, 9577 TS continuity errors
> > > Oct 13 21:00:00 tvt1 vdr[795]: cTS2PES got 83 TS errors, 3768 TS continuity errors
> > > Oct 13 21:00:00 tvt1 vdr[795]: buffer stats: 143068 (0%) used
> > 
> > If you get this errors with the signal from above, the frontend
> > is not the problem. It could be a DMA problem.
> > But since the card of the same making seems to work for other people,
> > it is possible that your card or your motherboard is subtly broken.
> > 
> > Why does VDR report two different error counts in the same second?
> 
> The first one is for the video, the second one for the audio data.
> 
> > What exactly are continuity errors and TS errors in VDRs view?
> 
> "TS errors" counts the TS packets where the TS_ERROR flag is set.
> "TS continuity errors" counts the packets where the continuity
> counter is not consistent.
> 
> See VDR/remux.c, cTS2PES::ts_to_pes().
> 
> With that many errors I guess there must be something fundamentally
> wrong with the incoming data.

Yes, certainly.

One note: iso13818-1 allows duplicate TS packets (same CC value) in some
circumstances, your code does not handle this correctly (especially:
duplicate packets and packets with errors do not seem to get dropped).
Also, if the discontinuity indicator is set, the CC may be discontinuous,
too. You might want to count legal dupes and discontinuites in VDR.

(I guess duplicate packets are used in fixed bandwidth channels for
additional error tolerance, instead of filling up the bandwidth with
stuffing some packets are repeated. But it doesn't seem to be used
widely, otherwise you'd have noticed before ;-)

Johannes


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