[vdr] Re: vdr-1.3.4 autopid and DVB-T

[Koen De Vleeschauwer <koen@mcvax.org>]

OK.  nit.c modified to ignore NIT's from the SFN at 834 Mhz and the 
problem still occasionally occurs; this time it sometimes happens when 
I tune to 810 Mhz.  An example:

Feb 19 12:28:42 pandora vdr[1222]: switching to channel 6
Feb 19 12:28:42 pandora vdr[1258]: transfer thread ended (pid=1258, tid=30751)
Feb 19 12:28:42 pandora vdr[1226]: NIT[7] 12555 'Quiero-Badajoz'
Feb 19 12:28:42 pandora vdr[1226]: NIT[8] 12556 'Quiero-CaÁZiza'
Feb 19 12:28:42 pandora vdr[1226]: NIT[9] 12557 'TDT CAM'
Feb 19 12:28:42 pandora vdr[1226]: has transponder 810
Feb 19 12:28:42 pandora vdr[1259]: receiver on device 1 thread ended (pid=1259, tid=31776)
Feb 19 12:28:42 pandora vdr[1222]: buffer stats: 13912 (1%) used
Feb 19 12:28:42 pandora vdr[1260]: transfer thread started (pid=1260, tid=32801)
Feb 19 12:28:42 pandora vdr[1261]: receiver on device 1 thread started (pid=1261, tid=33826)
Feb 19 12:28:42 pandora vdr[1226]: NIT[0] 12606 'TDT CAT'
Feb 19 12:28:42 pandora vdr[1226]: NIT[1] 12613 'Euskadi'
Feb 19 12:28:42 pandora vdr[1226]: has transponder 810
Feb 19 12:28:42 pandora vdr[1226]: NIT[2]  3333 'RGN'
Feb 19 12:28:42 pandora vdr[1226]: has transponder 810
Feb 19 12:28:43 pandora vdr[1226]: NIT[3] 12547 'Quiero-Pontevedra'
Feb 19 12:28:43 pandora vdr[1226]: NIT[4] 12548 'Quiero-Zamora'
Feb 19 12:28:43 pandora vdr[1226]: NIT[5] 12549 'Quiero-Donosti'
Feb 19 12:28:43 pandora vdr[1226]: NIT[6] 12552 'Quiero'
Feb 19 12:28:43 pandora vdr[1226]: NIT[7] 12553 'Quiero-Huelva'
Feb 19 12:28:43 pandora vdr[1226]: NIT[8] 12554 'Quiero-Catoira'
Feb 19 12:28:43 pandora vdr[1226]: NIT[9] 12555 'Quiero-Badajoz'
Feb 19 12:28:43 pandora vdr[1226]: NIT[10] 12556 'Quiero-CaÁZiza'
Feb 19 12:28:43 pandora vdr[1226]: NIT[11] 12557 'TDT CAM'
Feb 19 12:28:43 pandora vdr[1226]: has transponder 810
Feb 19 12:28:43 pandora vdr[1226]: NIT[12] 12600 'Quiero Global'
Feb 19 12:28:43 pandora vdr[1226]: has transponder 810
Feb 19 12:28:43 pandora vdr[1226]: taking NIT with network ID 12613
Feb 19 12:28:43 pandora vdr[1226]: changing transponder data of channel 1 from T:770000000:0:3:0:2:1:3:1 to T:794000000:0:3:0:2:1:3:1
Feb 19 12:28:43 pandora vdr[1226]: changing transponder data of channel 2 from T:770000000:0:3:0:2:1:3:1 to T:794000000:0:3:0:2:1:3:1
Feb 19 12:28:43 pandora vdr[1226]: changing transponder data of channel 3 from T:770000000:0:3:0:2:1:3:1 to T:794000000:0:3:0:2:1:3:1
Feb 19 12:28:43 pandora vdr[1226]: changing transponder data of channel 4 from T:770000000:0:3:0:2:1:3:1 to T:794000000:0:3:0:2:1:3:1
Feb 19 12:28:43 pandora vdr[1226]: changing transponder data of channel 5 from T:770000000:0:3:0:2:1:3:1 to T:794000000:0:3:0:2:1:3:1

I've looked at frequency allocation tables for dvb-t in Spain. There 
are three multiplexes. The one at 834 Mhz is a SFN; the other two are 
not. But sometimes the same frequency is used in geographically 
distinct areas. For instance:

Here in Madrid there are channels on 770, 810 and 834 Mhz.
In Euskadi there are channels on 794, 810 and 834 Mhz.
The TV stations that emit in Madrid on 770 Mhz are the same ones that 
emit in Euskadi on 794 Mhz.

If I tune to 810Mhz and vdr chooses the NIT for Euskadi then vdr 
changes the channels.conf entries for 770 Mhz to 794 Mhz, even though 
794 Mhz is not in use here.

On cable or satellite a transponder being announced is a pretty good 
indication it can also be received; but for dvb-t I don't think there 
is any way vdr can be sure a channel can be received other than first 
tuning to it.

regards,

koen

On Fri, Feb 13, 2004 at 05:40:29PM +0100, Klaus Schmidinger wrote:
> 
> Could you please modify VDR/nit.c in such a way that it completely ignores
> any NITs on transponder 834MHz? Does it then use the correct NIT on other channels?
> 
> If this fixes the problem, maybe a solution would be to ignore NITs in SFNs
> (provided we can figure out that a channel is part of an SFN).
> 
> Klaus


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