[mythtv] Patch to autodetect 4:3 Zoom aspect ratio

[Stuart Morgan]

On Friday 22 February 2008 13:53:17 Petr Stehlik wrote:
> I have a 16:9 display but most movies are broadcasted in 4:3 (with
> correct aspect ratio, I never seen a movie with incorrect aspect ratio)
> so they are pillarboxed. A good compromise for pillarbox on 16:9 display
> is "half zoom" AKA 14:9 zoom that maintains the aspect ratio and removes
> part of the black bars. The 14:9 zoom could be enabled automagically if
> the left&right side black bars were detected...

Petr, but the pillarboxing is done by mythtv? (OSD isn't full screen?) So it's 
the letterboxing which needs to be detected since that's the bit which occurs 
in the stream.

16:9 content broadcast at 4:3 looks like this in mythtv:
http://miffteevee.co.uk/imagebin/letterbox.jpg

The bars above/below the image are part of the original stream. The bars at 
the left/right are added by mythtv to preserve the aspect ratio. To correctly 
decide that this needs the 'half' or 'full' fill modes we need to detect the 
bars top and bottom.

-- 
Stuart Morgan