[mythtvnz] Using the Freeview EPG guide in MythTV

[David Moore]

On 07/03/15 11:45, Paulgir wrote:
>
> I see the Freeview DVB-T EPG now has 8 days of data included.
> Up until now I have been using http://epg.org.nz data.
> If I want to use the over-the-air guide,can I just check the "use on 
> air eit" boxes in Myth Backend set up and disable the running of 
> tv_grab_nz-py ? or is there other set up necessary?
>
> Paul
>
Interesting. If I feel the urge I will investigate further. But I am 
also somewhat disturbed by related things I have just read regarding 
what TVNZ and the BBC are doing. Here is a quote from the "Metadata" 
section at http://en.wikipedia.org/wiki/Freeview_%28New_Zealand%29.

"During the third week of December 2014, TVNZ tested using the same 
Huffman look-up tables the BBC implemented to force viewers to use 
approved Freeview receivers that restrict HD recording and viewing. The 
Huffman tables are being used to compress the EIT text used for 
terrestrial schedule event names and descriptions. From March 2015, TVNZ 
began compressing the EIT schedule again. Compressing the EIT text in 
the schedule would not achieve the same receiver use given the 
terrestrial EIT only has limited programme details. Receivers that don't 
use the BBC huffman tables will either display no details or display 
garbage characters."

If TVNZ is really compressing the EIT using Huffman coding then the 
MythTV EIT decoding code must be pretty clever to decompress it without 
access to the Huffman lookup table(s). (Unless the Huffman table is 
embedded in the EIT data in some standard way maybe?)

After reading about how the BBC got OFCOM approval to implement "content 
protection" for their HD service and some of the interweb comments about 
how this could affect MythTV users I am nervous about TVNZ's plans. As 
the paragraph above from Wikipedia says you can't decompress data that 
has been compressed with Huffman coding unless you know the Huffman 
decoding tree/lookup table. If TVNZ (and others?) follow the BBC path 
and compress the EPG and require users to get a licenced copy of the 
Huffman table then we'll lose our relatively simple access to the EPG 
over the air.

Also it could be the thin end of the wedge heading towards encryption of 
"premium" content although I don't see why this would be allowed on 
Freeview. But given what OFCOM allowed the BBC to do you never know what 
warped reasoning might allow Freeview content to be encrypted.

Hopefully my fears are completely ungrounded and we can continue on our 
merry, open source way with our EPG and recording working fine.