[mythtv] Looking for suggestions: Smarter Screen Grabbing

[Ramon Redondo]

Recently I changed my recording settings to start recording 2 minutes 
early, to catch the beginning of shows on networks that _don't_ seem to 
match up to 'standard' time.  A little while later I noticed that my 
screen capture previews for many of those shows ended up being for the 
show PRIOR...

After some looking around, I found that 
MainServer::HandleGenPreviewPixmap() always calls GetScreenGrab with a 
'secondsin' value of 64 seconds.

Ideally, I'd like to patch this to take into account the start offset 
(RecordPreRoll?) of the program, but the database doesn't currently 
store that information on a program by program basis. 

Since that isn't currently available, I've thought of several ideas:
1)  Use the _current_ RecordPreRoll and add 64 seconds to it to 
determine where to take a screen grab.
2)  Take the start and end time of the recording, find the 'middle', and 
add some offset (64?) to that.

I personally think that I prefer #2, although it would have to handle 
the case where a grab is requested before the program completes.

I'm more than happy to implement something, but I wanted to get some 
other opinions on this.
Any thoughts?

Ramon Redondo