[crawfish]

sending limited range RGB to the GPU is not a passthrough at all...
video data is YCbCr at y 16-235 and CbCr at 15-240.
video passthrough is not possible on a PC and a BD player can't do it too.

It's a straight conversion from YCbCr's actual 1-254 range to RGB that preserves BTB and WTW. It's passthrough in the sense I described here, which madshi agreed with in his reply to my message:

http://www.avsforum.com/forum/139-displa...st28112058

Not sure why you think a (standalone) BD player with YCbCr options can't do true passthrough. PCs can't do it because cards work with RGB 0-255 internally, and their YCbCr output option compresses all output from RGB to YCbCr right before putting it on the wire. This is the worst thing to do, because the levels round trip from 16-235 to 0-255 and back to 16-235 tends to introduce banding. I don't recall (standalone) BD players being described as doing this.

the best you can do is everything at full range RGB that's only one conversation. and of cause your screen has to support full range RGB.

Nope. The optimal setup for video is as I described. I also described the compromise mode you're talking about which achieves desktop/video consistency at the expense of expanding video from 16-235 to 0-255, throwing away BTB and WTW in the process, which does not happen with the optimal or passthrough mode I described.

ETA: I was interested to see my 2015 Sony BDP-S1500 only has a Limited Range RGB option, while my 2008 BDP-S350 has both Full and Limited Range. If you want consistency between HTPC and S1500, say, because you're going through an AVR with a single output, the passthrough mode I described for the HTPC and Limited Range for the S1500 is the only way to do it. In fact, I do exactly this, and my HTPC and S1500 measure the same using Calman and my profiled i1D3. They also both preserve BTB and WTW.