On Fri, 27 Feb 2009 21:30:35 +0000 (GMT)
Dominic Morris <d...@suborbital.org.uk> wrote:

> On Fri, 27 Feb 2009, Tony Houghton wrote:
> > I've had a quick look at the Freesat EPG patch for VDR to try to
> > understand how it works. I think I've read that the Freesat EPG is
> > broadcast on Eurobird (and only on one transponder?) whereas most of the
> > programs are actually broadcast on Astra 28.2E, but the patch doesn't
> > seem to add anything to VDR for selecting transponders.
> I believe that it's broadcast on all Freesat transponders, certainly for 
> me, tuning to a BBC channel starts pulling in all the EPG info.

I found some more useful information by Googling "Freesat Huffman".  One
page said the official transponder for the EPG repeats it every 30
seconds whereas it can take as many minutes to get the whole EPG on the
others. <http://forums.gbpvr.com/showpost.php?p=297759&postcount=6>. But
AFAICT the pids for SDT and NIT given there are either wrong or the
table_ids must be non-standard too.

> > I'd also like to find some more information about the Huffman encoding
> > tables it uses. Apparently these need updating periodically. Are the
> > tables broadcast alongside the EPG, but means to receive them hasn't
> > made it into the VDR patch (yet)?
> They're hardcoded into STB so the complete tables zip file won't need 
> updating - the only reason why the tables might need updating is if you're 
> using the "derived by observation" set, which I've not had a chance to do 
> recently - stick to the complete set and you can't go wrong.
> > I'd also like to know if and how Freesat's logical channel numbers are
> > broadcast and if there are alternative SDTs, PATs and PMTs especially
> > for Freesat instead of the BSkyB ones.
> As far as I've seen everything is fairly standard, though the tables are 
> off set by 3800 pids, so the BAT is at pid 3841. In terms of features I 
> suspect that if you look at how Freeview handles thing, add 3800 to the 
> pid then things will be the same - certainly TVAnytime is implemented the 
> same.

I haven't checked BATs or EITs yet, but Freeview seems to use standard
pids (from ETSI EN 300 468) for PATs, PMTs, SDTs and NITs. The standard
BAT pid is 0x11 so I don't see how simply adding 3800 works :-/.

TH * http://www.realh.co.uk

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