[linux-dvb] Descrambling suddenly stops

Manu Abraham abraham.manu at gmail.com
Tue Oct 25 13:00:21 CEST 2005

Andreas U. Trottmann wrote:

>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?

Your descrambling will stop when the CA_PMT changes. We will need to 
create a thread in ca_zap, which keeps sending CA_PMT messages to the CA 
module, maybe something in the order of say 5 minutes.


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