[linux-dvb] Possible patch for CAM/CI issues

Andrew de Quincey adq_dvb at lidskialf.net
Mon Nov 7 20:20:59 CET 2005


On Monday 07 Nov 2005 18:34, Andrew de Quincey wrote:
> On Monday 07 Nov 2005 18:31, Marco Coli wrote:
> > Georg Acher wrote:
> > > The signal integrity of some CAMs is quite bad. The have slow and and
> > > irregular rise and fall times for the clock, with varying setup/hold
> > > times for the data. This can lead to data corruption on the receiving
> > > side of the CI slot. AFAIK the Matrix cam was one of the worst I've
> > > seen. I can't imagine how one create such an "analog" clock signal from
> > > a digital source...
> >
> > I am sorry to hear that... Unfortunately for me, I can't consider a cam
> > change, because Matrix and Dragon, as far as I know, are the only ones
> > which can be programmed for NDS-Videoguard for sky italy.
> >
> > > In short: There is so much badly designed crap in the CAM market. It is
> > > a wonder that at least some CAM/receiver combinations work...
> >
> > But in all receiver I tried, my cam worked well, except for my nova card
> >
> > :-(
> >
> > Do yiu think, like Andrew suggested, that using a full featured card
> > (like the nexus-S one) could be a solution?
>
> I wonder if it would be possible to simple have some form of retransmission
> at the application level... I'll have a look at en50221.

Hmm, I've had a look. Unfortunately, even though the CAM control protocol is 
massively overdesigned for what is needed, it doesn't seem to provide any 
support for error detection or retransmission of corrupt messages!! :(



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