[linux-dvb] AV7110-based dvb-ttpci DVB card: Descramble an
inadvertently scrambled recording?
rjkm at metzlerbros.de
Wed Nov 2 11:00:33 CET 2005
Christoph Schulz writes:
> please forgive me if this is the wrong mailing list to ask this question.
> The problem: I made a TS recording with a Technotrend DVB-C card
> (dvb-ttpci driver, AV7110 based) from a scrambled channel.
> Unfortunately, the CAM was not properly initialized, so the recording
> wasn't decrypted but saved scrambled on the disk. Now my question(s):
> 1) Is it technically possible to replay the recorded TS stream through
> the DVB card, using the CAM to decrypt it? I read somewhere that you can
> feed an MPEG2 stream through the dvr device into the driver, but that
> then the software decoder is used. Does this mean that the hardware CAM
No, but it is not passed through the CI interface.
> cannot be used in such a case?
Yes, it cannot.
> 2) Does the scrambled MPEG2 transport stream contain enough information
> to allow a later descrambling to be performed successfully? I read
> somewhere that a similar card does not record all the ECM/EMM
> information needed for later decrypting. Is this true for my card?
You could record it with your card but you probably did not.
> 3) If the stream does contain the required information but the hardware
> is not capable of descrambling a recording, is it possible to use a
> software-based approach? I mean, is it possible to use/write a program
> that communicates with the hardware CAM directly to decrypt the
> recording stream?
Not without extra hardware. E.g. a normal PCMCIA interface would not
work and I am not aware of any that would do that.
> 4) If one cannot use the hardware CAM, is it possible to use a
> software-emulated CAM? (I read about it in some Windows forums.) Does an
> emulated CAM exist for Linux? And if so, does anyone know if it is legal
> to use it with your own recordings provided you have a legal
> subscription? (Of course I have a subscription!)
IANAL and I am certain there is some obscure interpretation of some
law which will say either way ...
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