[mythtv] DVB EIT in mythtv-eit

Janne Grunau janne-mythtv at grunau.be
Fri May 5 01:16:05 UTC 2006

On Thursday 04 May 2006 17:12, Rudy Zijlstra wrote:
> Janne Grunau wrote:
> >On Thursday 04 May 2006 10:40, Rudy Zijlstra wrote:
> >You will see one NIT with table id 0x40 (actual network) and maybe
> >several other with table id 0x41 (other networks). Each NIT
> > regardless of the table id value will hold one one or more
> > transport descriptors.
> Fine, this explains why network scanning on my cable network always
> fails. The network ID i have to give the STB is 1111. The NIT which
> is selected that way has a table id of 0x41 (other network).
> I guarantee though, that it is the valid NIT for my location.
> This is common cable behaviour. This was recorded on Essent in the
> Netherlands.

I can only say that Kabel Deutschland does the right thing(tm). They 
have only one NIT actual network and no NITs fo other networks.

> >>Important 1: only the TS referred to by the NIT with the correct
> >>network ID will be present on the cable!
> >
> >Cabel, satellite, terestial transmitter, something like that but it
> >doesn't depend on the network id, but the table id matters.
> See above. I happen to disagree. More importantly, so does my cable
> provider. (and most cable providers in EU).

At least Kabel Deutschland (biggest cable provider in germany) seems not 
to suck regarding DVB standard conformance.

> For SAT there is yet another reason to scan by network ID. When you
> have payTV, you have a subscription with Premiere, C+, ...
> At that point you are interested in services from them, and not from
> another. So in all cases you are interested in receiving a minority
> (the services you have a subscription on). This can be done by
> scanning on network ID.

Please be precise: you want to filter the scanning on the 
original_network_id? I'm pretty sure that the NIT on premiere 
transponders (Astra 19.2E) do also carry information for transponder 
with a different original_network_id. But I'don't understand why you 
wouldn't like to have the FTA programs even if you have a pay TV 
subscription. A better feature would be to add only encrypted channels 
you have valid subscription for.

> >>Important 2: The different network layouts may (and will) overlap.
> >>Leading to different TS having the same frequency. Of course, only
> >> 1 will actually be present (see 1).
> >
> >We handle only the NIT with table id 0x40. So this is not a problem
> > at all.
> And so any scanning i do on my DVB-C tuner fails.

Since your cable provider can't read or does not want to fulfill the 
DVB-specs. I have some ideas how to make scanning on specs-violating 
networks working but that will have to wait until the scanner works for 
standard conforming networks. This is hard enough.

> >>Important 3: this means you cannot tune based on SDT info. There is
> >>no 1-1 mapping between SDT and NIT.
> >
> >Of course there is. In the NIT of the actual network each transport
> > is specified by original_network_id and transport_stream_id. For
> > every combination of this two should exist only one SDT.
> In theory, yes. In practice: No.

Also in practice! At least for some networks. 

> >>Important 4: The same services will be referenced in different TS.
> >>(from different NIT). I actuality only 1 NIT is valid, and only 1
> >> TS will actually carry the service.
> >
> >Not a problem, we get the service information from the SDT of the
> > actual tuned transport. And there is only one SDT for each actual
> > transport.
> >
> >I haven't read your previous mail (was it send directly to Daniel?).
> > It might be that your cabel provider is incompetent and does not
> > rewrite the NITs in the transport streams it provides. But please
> > wait with
> I am willing to forward to the provider management. Do you want his
> answer on this one?

I doubt that they will answer at all. But I'm interested to hear why the 
violate the DVB-specs or choosed to follow their own "standard".

> By the way, your cable provider is most likely Telenet. As far as i
> know they do not use NIT-actual at all.

Don't be confused by my email address. I'm from BErlin.

> >complaints until the channel scanner is working for standard
> > conforming DVB networks.
> Some information for you: none of them (DVB-C) comply in that way....
> They tend to have 1 central HE, and distribute over their complete
> territory without having Multiplexors in between. So NIT is
> determined in the HE for all possible networks they have. And they
> tend to have several network layouts.

At least Kabel Deutschland in Berlin complies.

> For germany in case of private network you actually have to ignore
> the NIT in many cases. Many of those networks take a signal from SAT,
> trans-modulate to QAM and transmit without touching the NIT.

Some other small and broken setups. The tuned scan should work. It may 
not give correct channel names.


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