[vdr] Querying CAM doesn't work

Klaus Schmidinger Klaus.Schmidinger at cadsoft.de
Mon Aug 29 17:30:00 CEST 2005


Dominique Dumont wrote:
> Hello
> 
> Here are some explanation provided by a CAM developer.
> 
> ------------------------------------------------------------------------
> 
> Subject:
> Re: [vdr] Querying CAM doesn't work
> From:
> marc.abramson at free.fr
> Date:
> Mon, 29 Aug 2005 12:40:15 +0200
> To:
> vdr at linuxtv.org
> 
> To:
> vdr at linuxtv.org
> CC:
> Dominique Dumont <domi.dumont at free.fr>
> 
> 
> Hello Klaus.
> 
> you are 100% right. The EN50221 spec does clearly define a QUERY procedure.
> However, this query is not correctly handle by a lot of module, because for a
> lot of different CA_smart_card, the only way to be 100% sure if the smart card
> is able or not to descramble something is to request a real descrambling. But
> then, if it works, it means that the smart card will also have started to
> descrambling, and also (depending of what was in the encryption message), to
> use token or the card, or to start a preview...
> 
> 
>  From all the CA_system I know , there is only  one CA system for which the
> smartcard itself allow a query that will not start "consumming" anything, but
> only answer the query.
> ...

Hello Marc,

thanks for these in-depth infos.

So this means that in a device with more than one CAM that provides
a given decryption method, VDR will have to explicitly try to start
receiving the desired channel on each of them, and take the one that
actually delivers data. Well, so much for "standards"...

Klaus



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