ITV3 no EPG listings but other channels on same mux have listings

[martinu]

I noticed a "funny" this morning: the EPG listings for one channel (ITV3) were blank "(no show details)" from today until the end of time (well, for the next 7 days!) but various other channels on the same mux (eg ITV, Channel 4) had listings. I know that there have been changes with ITV3 moving from one mux to another, but I've had listings and used them to record since then.

I've righted the problem by going to Settings | Channels | Update EPG, but I'm curious as to how just one channel could have no listings, without it affecting other channels that get their off-air listings from the same mux.

I first noticed it after I upgraded from 4.1.0 to 4.1.1 just now. I'm not sure whether it existed before that, but I last made a recording (and so used the EPG) on 6 April.

I've attached log files in case it's something that needs to be looked into.

[Graham]

I'm curious as to how just one channel could have no listings, without it affecting other channels that get their off-air listings from the same mux.

In the UK, the EPG data for all channels is transmitted on all muxes. NextPVR scans all muxes because they do things differently elsewhere. I would guess that NextPVR uses the EPG data that it finds in the first mux or in the last mux that it scans.

I suspect that your missing data may have been because NextPVR got muddled between the old ITV3 and the new ITV3 and was looking for EPG data in the stream using the "id" of the old ITV3.

[ACTCMS]

I just checked my EPG (updated overnight) and there were no listings for ITV3 - I fixed the old/new ITV3 issue last week.

So I did a manual EPG update from Settings/Channels and just like for martinu ITV3 now has listings again.

Alex

[martinu]

Weird, because when ITV3 720x576 on PSB2 started broadcasting on LCN 10, I deleted the old LCN 788 channel altogether, so the only reference to the channel should have been to its new PID on the new multiplex frequency. And since I'd made that change, the EPG had been updating each day - until today when listings that had previously been present had vanished.

Anyway, it works now.

By the way, why is it that lots of other software (eg VLC, capturing from a USB DVB decoder, and various other TS analysis software such as TSReader) has problems displaying EPG listings for HD programmes, so you get a jumble of random characters. Obviously PVRs and set top boxes can do it, and so can Next PVR, so is there some decoding that "lesser" applications can't do?

[martinu]

Alex - I'm glad I'm not the only one. Maybe there was a temporary hiccup at the transmission process.

[Lao Pan]

Alex - I'm glad I'm not the only one. Maybe there was a temporary hiccup at the transmission process.

06:00 this morning had this problem on Mendip - Deleted channel and re-scanned then updated epg - same, same. :mad:

Hopefully someone has gone and put the plug back in so an epg update tonight might fix it.

[Lao Pan]

By the way, why is it that lots of other software (eg VLC, capturing from a USB DVB decoder, and various other TS analysis software such as TSReader) has problems displaying EPG listings for HD programmes, so you get a jumble of random characters. Obviously PVRs and set top boxes can do it, and so can Next PVR, so is there some decoding that "lesser" applications can't do?

UK HD Channels are encoded using Hoffman Tables to stop people "stealing " the information. NPVR has Hoffman decoding built in.

[martinu]

UK HD Channels are encoded using Hoffman Tables to stop people "stealing" the information. NPVR has Hoffman decoding built in.

Ah. Right. Why do they only do it for HD channels/multiplexes and not for SD ones? Or isn't there the capability of encoding using Hoffman tables in SD (DVB-T)?

[ACTCMS]

Ah. Right. Why do they only do it for HD channels/multiplexes and not for SD ones? Or isn't there the capability of encoding using Hoffman tables in SD (DVB-T)?

I found an interesting old article on the subject of Huffman coding relative to Freeview DVB-T2 here...

Alex