[MPlayer-dev-eng] Re: [MP] [PATCH] "turbo" mode

[Matthias Wieser]

Am Mittwoch, 15. September 2004 16:57 schrieb Guillaume POIRIER:

> So here's the PSNR comparison on 2nd pass:
> without turbo:
> PSNR: Y:42,09, Cb:43,18, Cr:43,06, All:42,41
>
> with turbo:
> PSNR: Y:42,08, Cb:43,16, Cr:43,05, All:42,39

And "standard mode" without some extremely cpu-hungry options:
PSNR: Y:42,08, Cb:43,17, Cr:43,05, All:42,40
at even more fps! 


OK, I did not run any comparison ;-) but as your patch decreases global 
PSNR it should be compared to mencoder without turbo mode but with 
slightly less CPU-hungry options.

And you should evaluate the PSNR differences between individual frames.
It could be possible that mencoder in turbo-mode thinks that some scenes 
are extremely bitrate demanding but with the options of pass 2 the scene 
isn't difficult to encode anymore. So your patch might change the 
distribution of bitrate in a way that leads to only slightly lowered 
global PSNR but to some really bad looking scenes.

Regards,
  Matthias