[linux-dvb] DVB-S2 and other (new) modulation standards

Klaus Schmidinger Klaus.Schmidinger at cadsoft.de
Wed Nov 23 15:15:28 CET 2005


Marcel Siegert wrote:
> hi klaus,
> 
>>I thought that when (if?) these new PC DVB cards come
>>out, they would be able to receive both DVB-S _and_ DVB-S2.
>>So from VDR's point of view this would just be one single
>>device and the device would decide, depending on the parameters
>>given to it when tuning, which method it actually is.
> 
> as different tuning parameters are needed, how to decide when structures/ioctls
> do keep backwards compatibility?

 From VDR's point of view I wouldn't mind if it would take some
changes in VDR to be able to work with DVB-S2 capable devices.
My actual concern was that it shouldn't be necessary to access
like frontend0 for DVB-S and frontend1 for DVB-S2. It should
remain one frontend. VDR of course will know whether a given
channel is DVB-S or DVB-S2 and can send different ioctl()s
to the frontend in each case.

>>Of course the current method used to distinguish the device
>>types in VDR (FE_QPSK = DVB-S, FE_QAM = DVB-C and FE_OFDM = DVB-T)
>>wouldn't work any more, so other criteria might be necessary.
>>But basically a DVB-S device would be just one single device
>>(with only one single frontend), whether it can only do the
>>"old" DVB-S, or both DVB-S and DVB-S2.
>>
>>At least that's how I would hope this would behave in the future.
> 
> afaik dvb-s2 is backwards compatible to dvb-s 
>  
> have a look at my mail some minutes ago, there's an example
> for a _maybe_ solution - also to keep old versions of vdr/neutrino/enigma/whatever working.

Well, whatever parameters or structs it takes to access a DVB-S2
capable device isn't the problem for VDR, it will have to be
adapted to support those channels, anyway. It's just that
there should be only one single frontend.

Maybe I misunderstood the whole discussion in this thread.
I just read about different frontends and was worried this
could go into a direction I wouldn't be happy with ;-)

Klaus



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