[mythtvnz] Using the Freeview EPG guide in MythTV

[Steven Ellis]

On Sat, March 7, 2015 12:48 pm, David Moore wrote:
> 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.

If they are using the same table as FreeSat this has already been
implemented in MythTV

https://code.mythtv.org/trac/ticket/6498#no1

It would be interesting to see of epgsnoop could be updated to include the
huffman tables.

Looks like another EIT grabber already has the huffman support merged from
MythTV.
 - https://github.com/ubaldus/tv_grab_dvb_plus



--------------------------------------------
Steven Ellis - Technical Director
OpenMedia Limited - The Home of myPVR
email   - steven at openmedia.co.nz
website - http://www.openmedia.co.nz