Question Windows 10 64bit pro no longer outputs WCG BT2020 color in HDR mode

bandyka

Well-known Member
G'day,

I wonder if anyone has come across this one.
I am trying to calibrate my OLED B9 and projector for that matter to HDR BT2020 color gamut.
I noticed that I can't see much of a difference between SDR and HDR either when watching movies or playing games. Sure enough after measuring it was the case. There isn't any difference in color between SDR Rec709 and HDR BT2020.

The PC is always in the correct mode SDR or HDR depending on the content I am using so is the display.

I ran dxdiag which reports BT2020 and the TV also reports BT2020 being received however my eyes and actual measurements see Rec709 output only in HDR WCG mode.
The Nvidia settings in use are 60hz 12bit 4:4:4, I've always used these in the past no issues.

The only change I can think of is the new GPU the RTX 2060 Super. The old one was a 1080ti. I think the OS is busted.
I also ran Spears and munsil banding test and the 8bit and 10bit parts look identical which sort of confirms my suspicion.
It suspect the TV only actually receives 8 bit color but I do not know how to confirm that on the TV.
See the image, this is HDR WCG mode which displays Rec709 gamut only.

What am I missing?

Thanks

DCI P3.jpg
 

andy1249

Distinguished Member
See here

rtx 2060 super is HDMI 2.0 , so bandwidth limit of 18gbps
You cannot do UHD 60fps HDR 4.4.4. 12bit over HDMI 2.0, from a PC , not enough bandwidth, you must go 4.2.2. Or 4.2.0, or drop resolution or framerate.

The HDMI handshake is almost certainly throttling down to the next available stable mode automatically.
 

bandyka

Well-known Member
See here

rtx 2060 super is HDMI 2.0 , so bandwidth limit of 18gbps
You cannot do UHD 60fps HDR 4.4.4. 12bit over HDMI 2.0, from a PC , not enough bandwidth, you must go 4.2.2. Or 4.2.0, or drop resolution or framerate.

The HDMI handshake is almost certainly throttling down to the next available stable mode automatically.
Yes you can do I did for years on other displays 4K 60hz 444 is exactly 18gbps it always worked fine for me:


regardless of that it won't do BT 2020 in any other resolution.
 

next010

Distinguished Member
You can only do 8-bit 444 at 4K 60hz via HDMI 2.0 it is impossible for anything else.

You only do 12-bit or 10-bit 444 at 4K 60hz if have a HDMI 2.1 capable GPU like the RTX-3080 series that's why so many LG owners are eager to get them.

As to the calibration issues that's out of my league, you could try asking here. I do know LG's PC mode is odd in a number of ways and HDR under windows is an issue.
 

bandyka

Well-known Member
hmm, then why was I getting the full 60hz 444 on my projectors??
 

bandyka

Well-known Member
Figured my issue out. Its a combination of things but in short I had to set Nvidia control to off and let Windows handle it set to Auto, it uses 8bit dithering which fixes banding and the color gamut problem. I only get about 92-93% of P3 as opposed to about 97% I should be getting but better than 72% only. It sucks but this seems to be the only way. For now, for whatever reason.
I add, if it was purely a bandwidth issue it would work at 1080p but it doesn't. Its got to do with the TV as it worked for years on my projectors.
 

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