TheSwissKnife Wrote:Thats right -I get no joy with YCbCr444 mode. I guess it boils down to NVidia (and others) not understanding that "useful digital video range" is "really" 16-255 (though 255 may not really usable in 8-bit mode over hdmi). <16 BTB is not necessary and can be clipped. A lot of screens won't show BTB and WTW but that does not mean it makes senses clip them as others want to see WTW displayed! It is ok to keep FULL RANGE of course but the point is we want the desktop and JPEG etc to be scaled so that BLACK is then 16 with max white probably 235 to cater for all users with the option to have it scale to 255 for slightly better result for those who don't mind such brightness levels.
Well, if you think about it, nvidia does not have another choice but to implement it the way they did with the current beta drivers.
If I'm not mistaken, you want support for xvYCC output...
You
might be able to get WTW with the old drivers and VDPAU studio color conversion, because enabling VDPAU studio color conversion applies a different colorspace conversion matrix when doing YCbCr to RGB conversion.
Without VDPAU studio color conversion enabled your video just gets expanded by XBMC to full range RGB while converting YCbCr to RGB. This will clip anything that is outside of "limited" YCbCr and that is why you won't get anything outside of that limited range no matter what you tell the nvidia driver to output to. The information was lost while XBMC converted YCbCr to RGB and the nvidia driver cannot get it back.
Now, with VDPAU studio color conversion enabled and full range RGB set you're basically doing something that does not really comply to HDMI specs as far as I understand them. You convert YCbCr to limited range RGB but you do not explicitly clip anything outside of the limited RGB range. If the video (like the AVS HD 709 test patterns from avsforum) happens to contain something outside of limited YCbCr while converting YCbCr to RGB it will end up outside of limited range RGB. I have no idea what your playback chain does with that, mine seems to be fine with it.
Long story short, if you only care about video quality (ignoring pictures and desktop) and your TV expects limited range RGB you should stick to full range RGB with VDPAU studio color conversion enabled. Otherwise you end up with XBMC expanding to full range RGB and the nvidia driver compressing it back to limited range. I doubt that this is a good thing and it might introduce additional banding in your videos.
The only thing I don't get is what happens when I set the beta drivers to output full range RGB. For some reason, black (as in RGB(0,0,0)) is no longer black but grey which doesn't make sense to me and does not happen with the stable drivers. I would have expected the same picture as with the old drivers. Or do the new drivers somehow shift the colors?