[linux-dvb] Re: Quality of dvb-kernel in upcoming 2.6

[Emard <emard@softhome.net>]

On Tue, Oct 21, 2003 at 12:56:48PM +0200, Holger Waechtler wrote:
> Michael Hunold wrote:
> >
> >>I got to the point that I applied 2 cards in parallel (antenna goes to 
> >>LNB IN of budget-patch and from its LNB OUT signal goes into LNB IN of 
> >>normal budget card) and, imagine, BOTH CARDS HAD THE SAME NETWORK 
> >>PACKETS MISSING!!
> >
> >
> >Ok, so apparently there's still something wrong with the packet capture 
> >stuff. 8-/
> >
> >>After measurement with the 2 cards it is clear to me that the loss 
> >>doesn't come statistically like from bad reception/too weak signal for 
> >>some tuner/decoder or by random dropping by the kernel going
> >>running low on input buffers. if it does, then 2 cards would
> >>easily cover the missing 10-20% of missing packets.
> 
> have you checked he continuity counter for these PIDs, are the packets 
> continous (this would mean that packets are lost in the networking code) 
> or are there already missing packets at the demux input (this would mean 
> DMA problems again)?

No, as I don't know how to do that (I will uncommend demux code
to get the continuity logs)

I'm nearly sure that DMA stuff is working well because
in case DMA is loosing data, I would see it with mplayer. I simulated
very small DMA errors and stream corruptions and it manifests as artefacts 
on mplayer picture, I just watch carefully the picture for 2-3 minutes and
even 1 single corrupted byte in whole DMA buffer can be easily spotted as
occasional random greeny artefact on mplayer.



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