The PCMCIA slot, which accommodates the conditional access module (CAM), is an integral part of the DVB-S card. It is not identical to the card reader, which you can attach to the serial port of a Linux-based receiver, such as a Dreambox.
I have a DVB-S card with CAM slot. If I have a CAM in that slot with a card does it decrypt the stream before the stream gets to the operating system? Or does the CAM act like a normal card reader that you would use with acamd or oscam and communicate via a com port?
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The PCMCIA slot, which accommodates the conditional access module (CAM), is an integral part of the DVB-S card. It is not identical to the card reader, which you can attach to the serial port of a Linux-based receiver, such as a Dreambox.
Thanks for that, but I'm still not clear on how it works. Are you saying that you would then get oscam or acamd to communicate with the CAM in the PCMCIA slot? Or does it decrypt the stream before the stream gets to the OS?
The cam does the decrypting. There would be no point to having the cam otherwise and you could just use a phoenix card reader instead.
Leroy
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I shall attempt to answer your questions as simply as possible, but a little technical background information is necessary.
The Digital Video Broadcasting standard, DVB-S, DVB-C, and in some countries, DVB-T, employs the Common Scrambling Algorithm, which is comprised of the Common Descrambling System and Scrambling Technology.
The specification for each is distributed separately under arrangements with the European Telecommunications Standards Institute (ETSI). (See my post at ).
The process, as a whole, employs the use of hardware, firmware and software.
The various encryption systems in use, Irdeto, NDS, Conax, Cryptoworks and Mediaguard, to name a few, are but one stage in the encryption/decryption process.
To aid your understanding, I have reproduced below, a simplified block diagram of a typical digital satellite receiver, either stand-alone, or as in your case, PCI card or similar.
The satellite receiver card you have, contains all the functional sections, illustrated in the diagram.
The DVB-S (Digital Video Broadcasting-Satellite), DVB-C (Cable) and DVB-T (Terrestrial) specifications, call for the use of a Control Word as the key element essential to the decryption process.
The Conditional Access Module in conjunction with a duly authorised Smartcard, process data extracted from within the Transport Stream (TS), in order to decrypt the Control Word for a particular channel.
The CAM then passes the decrypted CW (Control Word) back to the Transport Demultiplexer.
Upon receiving the Control Word, the Transport Demultiplexer allows all the data for a particular channel to pass through to the MPEG Decoder.
The MPEG Decoder then passes this data to other hardware sections, for further processing, until it finally emerges as (internet data), audio, video, epg (electronic program guide) or teletext information, to be displayed by a domestic television receiver.
In simple terms, the Control Word is a key, which activates a lock in a gate, allowing data to pass through!!
In the case of a PCI card or similar, used in conjunction with a personal computer, the PC's operating system (various flavours of MS Windows, Linux etc.), is used to provide an Interface, by which you can control the receiver, i.e. change channels, view EPG information, teletext, video etc.
The PC's Operating System (OS) does not contribute anything to the decryption of an encrypted channel.
Now, having said that, third party software has been developed e.g. ProgDVB and others, which can be configured to use various so-called "softcams", instead of the hardware conditional access module, fitted to the PCMCIA slot on the PCI satellite receiver card. Such "softcams" are not supplied with the program, but must be sourced elsewhere.
I have given you some information, which I hope has answered most of your questions. However, this answer, like all answers, simply begs other questions to be asked. For this, I suggest that you do your own further research.
There is much additional information to be found in forums and other sites on the internet, by using one of the many search engines available. Do a little "lateral thinking" in order to frame your search terms appropriately.
Last edited by tristen; 24-10-10 at 12:02 AM.
Fantastic answer thank you.
That makes sense to me now. When using a softcam (acamd) the CPU would still be idling at 1 or 2%. I thought that using a softcam would bring the stream decoding into software causing the CPU to do a lot of work, but what your diagram says is that the softcam is sending a signal back to the dvbs card and the card is then able to use it's hardware to decode the signal.
So it is up to the software developers (like windows media center) to support softcams or not which is of course a political decision rather than a technical one.
tristen (25-10-10)
With regards to Windows media center you could get it to work with card by using Progdvb as tristen mentioned and using "DVBLink TVSource" to intergrate Progdvb into Windows media center.
The downside if you have 3 applications running to do one job.
Mickstv
Well thats a bit strange.
You might also be interested in looking at Mediaportal which is a freeware mediacenter app. The story is you can set it up to use softcam's and Cam's. Maybe look into that on as well. Search for Mediaportal + Vpl*g setup.
whoops going a bit off topic.......
Mickstv
Last edited by mickstv; 25-10-10 at 09:59 AM.
I'll have to find out I helped someone setup a system awhile ago so i'll get in contact with him and see. But I've got a feeling the card in his computer was only dvb-s at that stage but it may have been upgraded since.
Thats the other thing I don't know if he's got the full package or hes just paying for the basic austar package ?
On a side note personally I don't see the point in having Poxstar it costs too much for what you get. More than enough programming on Freetv to watch.
Mickstv
Last edited by mickstv; 25-10-10 at 11:01 AM.
Now we're really off topic. I agree though, so many channels so little worthwhile content being produced.
Now to go off topic bigtime. I was talking to my mate just before and he stopped using the PC setup a few months ago and is now using the Austar mystar box that Austar setup for him. Not sure if he got the HD box or the normal. Plus they setup a second box for not much more on the monthy bill.
The card he had was just DVBS so no HD services anyway.
Mickstv
Last edited by mickstv; 25-10-10 at 05:34 PM.
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