[linux-dvb] Re: problems with Nova-T card in UK with new DVB driver

[Gregor Lawatscheck <gpel@mpex.net>]

At 22:45 28/04/2003, you wrote:
>Using the
>linux-dvb.2003-04-27 DVB driver from the VDR Developer FTP site + VDR
>1.1.29 (similarly for some earlier versions of VDR and earlier
>NEWSTRUCT drivers) gives the following behaviour using a Nova-T card
>in the UK:
>* tuning into BBC1 works well
> * tuning into BBC2, BBC3 and BBC NEWS24 (on the same multiplex)
>   rarely locks on
BBC1 always works, changing to BBC2 or News 24 afterwards shouldn't require 
it to lock the frequency again as they are on the same multiplex. It merely 
has to change the PIDs - but it seems to have problems with those two 
channels somehow. I'm not sure whether this is a driver newstruct prob or a 
vdr problem. It doesn't appear to be related to transfer mode either, as 
people with full cards have reported the same problem. I believe to have 
heard that people with dxr3 cards also have this issue - this would mean 
it's unlikely to be a av7110 problem. Correct me if I'm wrong.

It's quite freaky that BBC1 *always* works but the other two or three 
channels on the mux don't. BBC1 has PIDs 600:601, BBC2 610:611, BBC 3 has 
620:621 and News 24  640:641. It makes no sense to me why BBC1 would work 
and the others wouldn't.

I've tried tracing this a couple of times: What happens here is that the 
DVB-T card tunes just fine and also seems to set the PID correctly and 
recieves data. In fact, when the error crops up, it usually outputs a 
couple of seconds of sound as well before it stops but never a picture. 
What actually appears to happens is that decoder doesn't seem to like the 
input anymore after a very short time and doesn't stops reading the the 
buffer. The buffer then goes to 100% and nothing happens. I might be 
imagining this but increasing the buffer to redicilous high values such as 
50 MB seems to give a higher success-rate at getting working picture / 
sound output.

Disabling audio by setting its PID to 0 doesn't doesn't do the trick 
either. Setting just the audio PID and not the video PID works fine though 
- it then outputs the audio for as long as I wish.

>* other channels usually work well, though I've seem some odd
>   behaviour after VDR has difficulty locking onto a BBC multiplex
yes true. Sporadically Channel 4 and some of the "worthless" travel and 
shopping channels don't show a picture.

> Any clues as to what I should try next?  Are other people having
> similar problems?
Yes, same problems. Just like you I'm using vdr 1.1.13 with the 0.9.4 
version of the driver as my "stable" solution. 1.1.13 is one of the last to 
support the old driver model but one of the first to support the extended 
settings required for DVB-T in channels.conf. 1.1.13 / 0.9.4 has very 
sporadic problems tuning to Channel 4, but it usually works the second time.

Maybe this problem has something to do with the new PCR stuff, but then 
again that only seemed to be a problem with recent firmwares and this is 
not a firmware issue, as newstruct and old firmware doesn't cure the 
problem. Moreover the problem has been there ever since the very first 
newstruct driver in CVS but worked with the last "oldstruct" in CVS. The 
tuning code didn't change much.

I'm never sure whether to discuss this on linux-dvb or the vdr list but as 
you started the thread here I might as well continue posting here. 


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