[mythtv] Ticket #2416: Provide analog sources with dvb eit

[warpme]

Robert,

Let me share my view on subject.

I'm glad You discover EIT cross-source might be useful for MythTV users. 
I'm using it daily and without it my whole DVB-T subsystem is useless.

So Q is how to implement it in best way.
I see 3 potential approaches:
1.copy on DB tables level,
2.use external supporting tools (eit_cross.py + mythfilldatabase),
3.do it within myth,

I will not analyze options in simplicity of implementation or elegance dimensions as I think here is one very basic criteria which practically excludes 1 & 2 from any further analysis: EIT data coherence.

EIT data source has constant nature. Unfortunately any other than 3\ method offers periodic nature from destination point of view.
This periodicity can cause potential EIT data divergence between source & destination data sets.
Such divergence can lead to potential issues with scheduler (as it will see the same show on the same call-sign channels with different times. I think I already meet such issues in my system).
Only solution for coherence is atomic (from sched.point of view) operations on EIT data.
Patch in question is doing exactly this and this is it's beauty.
I think - if we ever considering cross-EIT feature - approach from this ticket is one from best solutions.     

Now what think about example of potential UI design:

We can assume this feature has max. sense if user has 2 different sources for the same set of channels.
Assuming this it means user will assign them the same call-sign as this allows scheduler to use them equally from scheduling point of view (maybe with some different priorities, filters,etc).
This means eit_mapping table can be build automatically by sql statement which will fill mapping between source & destination for all channels having the same call-sign (in ticket I put example of such sql statement).

From UI perspective I see following example of implementation:
- In video-sources setup section add additional EIT cross-source screen with:
- on-off tick,
- 2 fields: VideoSource src name & VideoSource dest name,
- help text telling what it does ("this feature will copy EIT data from src name to dest name for all channels having the same call-sign. It is not relevant for following cases: <blah blah>")

IMHO it is elegant as it:
-implementing EIT cross-sourcing it proper way (data coherence)
-is very simple from user perspective (3 parameters + understanding description text)
    
I hope above will encourage You to change Your mind regarding eit-cross source feature in MythTV.

br