[linux-dvb] DVB-S2 API vs. HVR4000: When?
abraham.manu at gmail.com
Fri Nov 2 23:01:39 CET 2007
Manu Abraham wrote:
> Hi Johannes,
> Johannes Stezenbach wrote:
>> On Sat, Nov 03, 2007, Manu Abraham wrote:
>>> When Johannes stated: handling multiple streams is as simple as setting
>>> a stream id, well it is not that i blame him, the specs look that way. There
>>> are couple of ways the same thing is done for example. You apply a
>>> wrong one and the API is screwed and you have to bear that brunt for
>>> a long time to come.
>> Hey, if you know more than I do then please explain it to me.
>> Until proven wrong I continue to believe that there isn't any more
>> magic to handling multi stream mode than choosing one of them
>> by writing the stream id into the appropriate demod register.
> ;-) of course. I have learned it the hard way, that proving a person
> wrong can be disastrous.
> Nevertheless i will explain my understanding, eventhough not a
> great one. :)
> If you see H.2 and H.3, the difference is between CCM and VCM
> (Note: that both are cases of multiple "TS's")
> H.2 (CCM) is applicable for DVB-T muxes. Here there is a HP/LP
> stream selection in some fashion combined with the merger/slicer
> where stream id is used.
> It is a combination of both, rather than a simple stream id.
> (In this case Rolloff=0.20, Pilots do not exist) in this case the
> QPSK stream is with FEC 5/6
> H.3 (VCM) is applicable for a HDTV/SDTV mux. here it is quite similar
> to H.2 exception that (In this case Rolloff=0.25, Pilots do exist)
> in this case the QPSK stream is with FEC 3/4 and the 16APSK stream
> is with FEC 3/4
Also, i forgot to mention one more thing, 16APSK is denoted as
4 + 12 APSK, (for the demod) not sure why either.
> H.2 is playing with the DVB-S signal level (saturating a transponder)
> where as H.3 is using differential protection. It is not very clear how
> both of these are distinguished from each other.
> Also, on the demod other than the MIS flag (according to the specs)
> there is another bitfield to select the HP/LP stream, which makes it a
> bit even more confusing. There exists some clarity, but again there are
> some clouds which hinder how it looks.
> I am not really very clear on handling this. We will get more clarifications
> the coming days.
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