[mythtv] alternative method for commercial skipping

[Chris Pinkham]

> > All channels are so kind to display a logo/icon in a corner of the 
> > screen when a program is showing, but not when the commercials are on...
> 
> I think it is generally the same here by now (unfortunately), but I 
> don't think you can rely on it. I hope there are still stations which 

I think logo detection can be used but not completely by itself.  I've
seen logos come and go during one 5-minute section of a show.  This would
play havoc with commercial skipping. :)  Logo detection in combination
with scene change rate information, audio volume/silence, etc. could
be fairly accurate though.

> But another method might work, at least here in Germany: Stations are 
> required to separate advertizing and programme, and they do that by 
> displaying their logo / clip / corporate art in full-screen before or 

This is the still-frame detection I was mentioning.  Still probably not
good enough to work by itself, but in conjunction with other information
it could be pretty good.

> If you want to go with that fullscreen logo route (not sure, if your 
> stations also do that), you could let the user hit a key when he sees 
> that ad-start and end and then just store that frame for that station.

I think that generic detection methods such as just detecting a still-frame
would work better than trying to capture every still-frame ad that every
station uses.  Maybe I'm mistaken though.  I'm "spoiled" by the fact
that the blank frame detection seems to work like 90% of the time for me.
The scene change detection stuff I just added hopefully will take that
a little closer to 100%. :)

Chris