[linux-dvb] Hauppauge Nova-T problems - Progress at last!

[Ed Wildgoose <ed@wildgooses.com>]

Thankyou so much Robert.  The clue to at least some of my problems is 
this PCI burst length setting.

However, having tried values down to 16, it was still causing little 
errors, so I went down to using 0x00, and this seems to work properly at 
last! Wahoo!  I actually then tried 0x00030000 which should be a fifo of 
32, with pci burst of 1.  I'm assuming that this will be better than a 
straight 0x00?  (Any opinions?)

Now, some other notes on this.  The error rates are much worse using the 
gentoo gs kernel sources, than say, the ac kernel sources.  I haven't 
done any great tests, but since I used the same .config file the main 
difference is probably the "low latency" patch in -gs.  Does this make 
sense to anyone that the low-latency patch would cause problems with pci 
bursts?  To be clear though I am still having problems even with the -ac 
kernel, so the low-latency (if indeed that is the problem) is just 
exagerating the issue.

Anyway, with a pci-burst of 1 and a fifo of 32 I have one remaining 
issue which is that the sound is hideously out of sync with the picture 
when viewing in mplayer.  I have uploaded a few seconds of sample at:
http://www.wildgooses.com/test.ts

I wonder if someone would be kind enough to check this on their system 
and tell me if it plays OK.  For me there is about a 1 sec delay, with 
the sound behind the audio.  However, it plays fine in mythtv (which 
uses libavcodec) so I think this is a fixable player issue, but the 
point is that the stream from the full featured DVB card plays fine on 
this system.

Now bearing in mind the pretty low levels of data is there any reason 
NOT to lower the pci-burst setting.  Are we really gaining anything by 
leaving it this high?  Seems that it just leads to potential problems?  
For what it's worth I see the same problems under 2.6 test 3, so 
advancements in the kernel there aren't helping (for example).

Thoughts?

Thanks so much to everyone who has helped.  I really appreciate the 
friendliness and helpfullness of the people here.

Ed W


Robert Schlabbach wrote:

> From: "Edward Wildgoose" <ed@wildgooses.com>
>  
> > However, the picture is now jerky, it plays smoothly for a few frames,
> > then hiccups, then plays smooth for a bit longer.  Appears to be 1-2
> > hiccups a sec giving a kind of jerky progress to moving objects.
> > Sound is out of sync as well.
> >
> > I guess after that I need to start disabling the onboard hardware and
> > see if I can't get this card working.  But assuming that it is some
> > kind of corruption on the PCI bus, then are there any tips on debugging
> > this or preferably making things cooperate.  I tried bumping up the
> > PCI latency on the dvb card to 128, however, this didn't appear to
> > make any real difference...  Guess it's back to fiddling
> >    
> FWIW, these are exactly the symptoms I had on a SIS chipset with a budget
> card. These cards appear to be very timing sensitive. The parameters to
> play with are the SAA7146A "FIFO threshold" and "PCI burst length"
> settings. Settings I found to work well:
>
> 1. PCI burst = 32 DWORDs, FIFO threshold = 32 DWORDs - This one handles
> even a 40Mbps DVB-Cable stream on both i440BX as well as i850E chipsets
> (don't have others to try).
>
> 2. PCI burst = 16 DWORDs, FIFO threshold = 16 DWORDs - seems to work
> equally well.
>
> 3. PCI burst = 16 DWORDs, FIFO threshold = 32 DWORDs - The only setting
> which allowed me to make a DVB-T budget card work on a SIS 651 chipset.
>
>  
> > Just for reference this is an Asus P4P800 board.  I don't suppose that
> > anyone else has one of these and could say that it works for them with a
> > budget card?
> >    
> I don't have any experience with the i875 chipset yet, so please try the
> above settings and let us know if you find any combination that works on
> this chipset!
>
>  
> > The full featured card works fine... (well apart from crashing
> > frequently...)
> >    
> The full featured card cannot pass an unfiltered MPEG-2 stream, and if it
> passes MPEG-2 packets, those are not only lower data rates, but also
> buffered by the AV7110, thus making the transfers much less timing
> sensitive... So it's not surprising you are seeing PCI timing issues now
> you did not have with the full featured card.
>  



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