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

Steve Toth stoth at hauppauge.com
Thu Nov 24 00:29:15 CET 2005

Johannes Stezenbach wrote:
> On Wed, Nov 23, 2005, Steve Toth wrote:
>>>>> 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 
>> Correct.
>> For what it's worth, on the multiple frontend issue (not s2 related)... 
>> A board will appear with some or all of the following features before 
>> you know it. Analogue PAL, DVB-T and DVB-S on a single bridge. 
>> Personally, it's more logical to me two have two different frontends, 
>> one for S and one for T. Anything else feels like a hack.
> Think of a frontend as a device which outputs an MPEG-2 TS.
> The number of TSs you can receive simultaneously determines
> the number of frontend devices.
Interesting. That's the exact opposite of what I've always thought of as 
a front end. A front end to me means an implementation of a tuner/demod 
and/or stream. So, for example - even though a hardware products is only 
capable of delivering one physical stream at once, it may have two 
frontends which expose the two different behaviors in the same design.

>> Analogue tends to take care of itself through v4l, this probably should 
>> change longer term.
> Analog and digital TV with one tuner is not optimally integrated, but
> I don't think you should replace v4l with something else because of this.
> There isn't that much left to do.
I agree on both counts. I also agree that having a unified tuner model 
would be good idea.

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