[linux-dvb] Descrambling suddenly stops

Andreas U. Trottmann andreas.trottmann at werft22.com
Tue Oct 25 12:43:44 CEST 2005

Hello Linux-dvb,

After the really great news that descrambling with ca_zap and a
Twinhan clone Technisat SkyStar 1 CI now works, there is a minor

Basically, after a certain time (which can range from two minutes
to several hours), descrambling suddenly stops, and the stream I
get from /dev/dvb/adapter0/dvr0 contains no sensible audio/video
data anymore.

Running ca_zap again (with the same parameters as the initial
run) makes the stream work again.

The first "solution" I tried to remedy this situation was to run
ca_zap periodically in the background. While this sort of cures
the problem (no long-time freezing anymore), it sometimes causes
a disruption of the stream right at the moment ca_zap is run.

Is there any better way to do this? Can we send something like a
"keep alive" command to the CAM that doesn't disturb a
descrambling operation that's already in place?

Or, is there a way to programmatically find out when the CAM
needs to get "reminded" of the fact that it should descramble, so
we don't have to run ca_zap every couple seconds, but only when
it's really needed?

In case this is important: I'm using a standard ("red") Viaccess
CAM with a smartcard to descramble SRG (Swiss national TV)
channels on Hotbird.

Any hints would be greatly appreciated.

Andreas Trottmann
Werft22 AG
Tel    +41 (0)56 210 91 37
Fax    +41 (0)56 210 91 34
Mobile +41 (0)79 229 88 55

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