[mythtv] Fixed offset, wrapped image recording from NTSC G200TV

[Colin Panisset]

I've just fixed a problem in 0.12 (probably still in 0.13, though I haven't 
had a chance to try that yet) that's made MythTV almost unusable for me for 
quite some time.

Whenever I recorded or watched live TV, the image would be shifted left about 
32 pixels, and the left-most side would wrap back onto the RHS of the screen. 
Capturing with lavrec didn't have this problem, so I knew it wasn't a 
hardware fault.

The problem lies in NuppelVideoRecorder::MJPEGInit() where the initial 
resolution is chosen. The max x res for a G200 is 800, which ends up being 
set to the Myth max of 768 -- but this causes the above wrapping problem.

I don't know if other NTSC G200 users have seen this -- I've never seen any 
mention of it on the list -- but I fixed it by forcing the max x res to 704 
instead.

I haven't provided a patch, since the problem doesn't seem to be widespread 
and I don't want to force everyone's max width to 704 for no good reason, but 
I hope this information at least helps someone else out.

Oh, one other thing: it's pretty confusing to have the ability to set the 
capture resolution against the MJPEG encoder, when the actual resolution is 
solely dependent on the hardware decimation setting. That wasted quite some 
time in tracking this down, right there...

  -- C.