[mythtv-users] UK EPG ITV Channels Problem

Stuart Auchterlonie stuarta at squashedfrog.net
Tue Dec 5 12:34:19 UTC 2006

Mr. Demeanour wrote:
> Stuart Auchterlonie wrote:
>> I can almost guarantee that you find the information on some muxes 
>> and not on others.
> Interesting results:
> * BBC ONE and BBC Parliament recover a lot more data than any of the
>    other muxes. BBC ONE reports about 35,000 packets; BBC Parliament
>    reports 26,000. Others report between about 600 and about 2,500.

This is what i expected. The BBC Muxes carry the most complete
EIT of any mux.

> * The ITV data remains incomplete (missing, in fact). There is no
>    listings description or title for ITV1, ITV2, ITV3, ITV4, E4, E4+1,
>    MORE4, Five, UK History, Five Life or Five US. I don't use any other
>    channels.

I've looked at my available data again and have description data for
all these channels all the way up to the 12th.

> * Freshly-collected Programme data is present up until 1:00am on Tuesday
>    Dec 12, ending at roughly the same time for all channels. Title and
>    description are absent at the end of this interval as they are for the
>    present timeslot.
> If the data isn't retrieved by tv_grab_dvb, then I can't see how it can
> be grabbed by the internal EIT grabber. I thought they were both working
> on the same data?

They are both working on the same data, however the data changes over 
time. The broadcast data includes little bits of information which the
scanner uses to determine what the "best" information for any given 
program is. tv_grab_dvb basically grabs a snapshot of this data, which
may or may not be the best information for that program.

There are 3 main types of EIT data.
1. now/next data
2. 0-3 day schedule (ie. next 4 days)
3. 4-7 day schedule (ie. 4 days after that)

Then there are 2 destinations carried.
A. This Mux
B. Other Mux (also known as cross carried info)

When you put both of these together there are 6 EIT sources.
I'll list these in order of "best"
A1, B1, A2, B2, A3, B3

Each time you run tv_grab_dvb you are taking a snapshot of
the available data, which will include smatterings from all
of the EIT sources.

What the EIT scanner does is pay attention to the source that
provided the EIT information. If the new data comes from a
source that is "better" than the previous information, then
the new information is used instead. This continues until
the "best" information is obtained. Additionally it refuses
to replace a description (or subtitle, or title) with empty
data if it arrives.

Here endeth the lesson on EIT data :)



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