[XviD-devel] fast qpel refinement

[Michael Militzer]

Hi,

Quoting Radek Czyz <syskin at ihug.com.au>:

> 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.

Did I never post any benchmarks? ;-) At least I remember I sent some 
infos to Koepi regarding 'Turbo mode' (which also uses fast qpel). I've
attached a small text file with some numbers how 'Turbo mode' compares to
regular high-quality settings...

> 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.

Fine. Of course it was intended from the very beginning that the additional
halfpel checks to find the 'second-best' match should be avoided, but I
was too lazy to rewrite the whole refinement - so good that you did this
now :)

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

BTW: Any results already from your tries to implement a fast R-D optimized
refinement?

Michael
-------------- next part --------------
1 bframe + qpel + Quality 6 + VHQ1 + cm, Quant 4 | avg. Frame size | PSNR | Turbo mode: | avg. Frame size | PSNR
Container                                             336            38,28                          325      38,29
Silent                                                569            38,14                          567      38,13
News                                                  563            38,8                           558      38,82
Foreman                                               935            37,07                          935      37,02
Paris                                                2656            37,93                         2641      37,93
Tempete                                              7177            36,31                         7200      36,3
Mobile                                               9524            35,7                          9557      35,69

Avg. Bit _Reduction_: 0,63%, Average PSNR loss: 0,007 dB

1 bframe + qpel + Quality 6 + VHQ1 + cm, Quant 8 | avg. Frame size | PSNR | Turbo Mode: | avg. Frame size | PSNR
Container                                             152            33,91                         148       34
Silent                                                277            33,53                         273       33,52
News                                                  273            34,08                         270       34,14
Foreman                                               383            32,97                         375       32,9
Paris                                                1247            33,07                        1232       33,08
Tempete                                              2692            31,9                         2687       31,89
Mobile                                               3716            30,87                        3726       30,87

Avg. Bit _Reduction_: 1,19%, Average _win_: 0.01 dB