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

[Petr Stehlik]

Stuart Morgan wrote:
> 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

I realized that while writing that paragraph so I added second paragraph 
where I explained it to myself and others :-) You probably couldn't 
continue reading after the 1st one (and I am not surprised :-)

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

Right, wikipedia calls this "windowboxed" but that's only how it looks 
on 16:9 display, the stream itself is just pillarboxed.

> 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.

You're right, so Mårten please ignore the left&right black bars 
detection idea :-)

Petr