[XviD-devel] fast qpel refinement

[Radek Czyz]

Hey everyone,

I think I finally rewrote fast qpel refinement, first implemented by 
Michael. It turns out to be a very very nice idea.

I don't think I've ever seen any measurments so here they are. Defaults, 
qpel, no bframes, second pass, high-motion scene.

Full refinement: 	2:25 (21.90fps), psnr 42.37 dB
Fast refinement (new):	2:11 (24.24fps), psnr 42.29 dB

For reference:
Fast refinement (1.0 tree):  2:14 (23.70fps), psnr 42.30 dB
Halfpel:		1:56 (27.38fps)

I still don't understand why new code gives different psnr than the old 
one, but I'm not going to worry about it too much :P
New code is faster because it combines halfpel and qpel refinement, 
avoiding many halfpixel checks.

I'll clean the rest of the code (I currently have both old and new code 
in one file) and commit to HEAD.

:)
Radek