Originally Posted by madshi
I've just talked to Microsoft and NVidia. And the current situation is as follows:
1) In Windows 10 Creator's Update there's a new option in the OS display settings dialog named "HDR and Advanced Color". If you turn this option off, your TV will always be in switched into SDR mode. If you turn this option on, your TV will always be switched into HDR mode. Windows does *not* support dynamically switching HDR mode on/off while you're playing an HDR movie (or playing an HDR game)! It's currently not supported, and there are no plans to add support for that. Basically Microsoft believes that if you want to use HDR at all, then you want your PC to always drive your TV via HDR mode.
2) If you switch the "HDR and Advanced Color" option off, your TV will always receive SDR from the PC. If you play an HDR movie in this situation with the madVR option "passthrough HDR content to the display" activated, the OS will perform a low quality HDR -> SDR conversion behind madVR's back. Consequently, HDR content will look "ok", but the quality is not really good. SDR content will look "perfect", though.
3) If you switch the "HDR and Advanced Color" option on, your TV will always receive HDR from the PC. If you tell madVR to "passthrough HDR content to the display" in this situation, HDR movies should look "perfect". If you play SDR content in this situation, the OS will convert SDR to HDR behind madVR's back. Consequently, SDR content will look "ok", but it will not be perfect.
4) Currently HDR and fullscreen exclusive mode is a problematic combination atm. It's partially the fault of the OS, partially of the GPU drivers, partially of madVR. It's not clear yet if this will be fixed, or when. Generally, Microsoft wants to get rid of fullscreen exclusive mode. It might suddenly disappear in a future Windows 10 version.
5) Nvidia comes to the rescue of all HTPC users who want perfect quality for both SDR and HDR content: Nvidia's private HDR API allows madVR to dynamically switch the TV into and out of HDR mode, as needed.
6) The current madVR build has a bug where Nvidia's private HDR API is only called properly in the 32bit madVR version, but not in 64bit. This will be fixed in the next build.
7) All post-Creator's-Update Nvidia drivers have a bug which result in madVR being able to switch the TV into HDR mode, but switching the TV back into SDR mode fails. You can work around this by either using Windows 8.1 instead of Windows 10. Or by installing older Nvidia drivers. E.g. with Nvidia driver 376.33 dynamic HDR switching works perfectly fine in Windows 10. Nvidia is aware of the bug in newer drivers and plans to fix that soon.
As it stands right now, for all Windows users who want to do both SDR and HDR playback in perfect quality, I can only recommend Nvidia GPUs, because only Nvidia's private API allows madVR to dynamically switch the TV between SDR <-> HDR. I'm talking to Intel, maybe they will add a private API, too. Unfortunately my AMD contacts have gone silent.
I still recommend Windows 8.1 as the best media play OS right now, as I've done for months. Windows 10 still has many stability issues, furthermore Microsoft is going into a direction which is very bad for HTPC users.
Thank you for your answer and research !
So, about 1)2)3) I'd figured that out thank you for the confirmation, I suppose I have to switch it everytime but well there aren't too many HDR movies around (or true for that matter) so I'll settle with that until microsoft changes his mind ?
5) I'm very happy to read that, can you please explain to me the right way to use it ?
6) So I just have to wait the next madvr build and enable the nvidia private API, and i'll be hapi ?
7 : thank you for the information and research again
I currently am using windows 10 and would have a lot of work going back to 8.1, and also am very happy with some of windows 10 features and solution for all my other applications for this computer (it's my only PC and I use it to work, for gaming and as a HTPC, which makes things difficult to combine)
I thank you again for this reply which was exaclty what I was asking.
Good day to you !