MadVR HDR oddity with exclusive mode?

[Blue_MiSfit]

Hello!

I'm lucky enough to have an nVidia GTX 1080 and an LG OLED55B6-P display supporting HDR10 and Dolby Vision.

Using the latest Windows 10 Creator's Update, MadVR 0.91.11 in MPC-HC, and latest LAV filters, I can decode 10 bit HDR HEVC in hardware, and HDR content does display properly on this monitor when I'm in windowed mode. When I switch to fullscreen it does not display correctly. Specifically the "HDR" indicator on the display disappears and the colors look wrong.

I determined this was because in full screen exclusive mode I'm sending 10 bit to the display, whereas the desktop is standard 8 bit. Disabling full screen exclusive seems to work right.

However, this seems totally wrong!!! HDR10 is 10 bit.. right? So, I'd expect the normal 8 bit desktop to look wrong, and full screen exclusive using 10 bit to look correct!

What's happening here? The image looks nice but I do see some banding. Maybe this is related to the fact that it's 8 bit instead of 10? Or maybe that's just how my sample clips are encoded. Not sure...

[nevcairiel]

Fullscreen exclusive mode with HDR is just broken right now.
Refer to this post by madshi: https://forum.doom9.org/showthread.php?p=1810891#post1810891

There is some further clarification a few posts after this one, and NVIDIA might fix this in their drivers in the future.

For some clarification: HDR is not directly tied to the bitdepth. You can have HDR on any bitdepth, that the standard is called HDR10 and uses 10-bit is not really important.
With decent dithering, you can definitely get HDR on 8-bit to look OK (dithering is inefficient to encode in videos, so that only applies to display output, you definitely want 10-bit encoded videos).

PS:
This was posted just yesterday, should've been able to find it. =p

[Blue_MiSfit]

Ah, thanks. That 2000+ page thread is pretty daunting :D

[Blue_MiSfit]

Is 10 bit output possible without fullscreen exclusive?

[Asmodian]

Only when using an HDR display and having "HDR and Advanced Color" enabled in Windows, not otherwise.

[madshi]

I'd recommend to use a driver between 376.xx and 380.xx, then everything should work as expected. With the latest drivers, you have to disable FSE mode for now.

If you have banding in 8bit windowed mode, then you either have dithering disabled in the madVR settings (which is a bad idea if true). Or alternatively you're HTPC configuration might be bad. Please make sure your GPU output is set to RGB 0-255 (PC) in the GPU control panel.

[Blue_MiSfit]

Thanks, guys!

It looks like enabling "HDR and Advanced Color" in Windows is generally a bad idea right now, right? The nVidia APIs switch properly (minus the lack of FSE)?

[madshi]

Yes, when using an Nvidia GPU.