Vulkan games say “HDR not supported” on a virtual display: the fix
NVIDIA and AMD Vulkan drivers hide HDR from games on a virtual display. Punktfunk's Windows installer ships a Vulkan layer that shows it to them again.
The stream and DirectX games are in HDR, but Doom: The Dark Ages or another Vulkan game says your device doesn't support HDR.
Why it happens
A Vulkan game asks the GPU's Vulkan driver which colour spaces the display offers. On a virtual display, NVIDIA's and AMD's drivers leave out the HDR ones, so the game turns HDR off, although the driver would show an HDR picture. DirectX 11 and 12 games ask Windows instead. Games running through DXVK are affected, because DXVK draws with Vulkan.
What to do
- Install the Punktfunk host with HDR Vulkan layer ticked. It is on by default; if you unticked it, rerun the installer.
- Stream in HDR: HDR on in your client, with HEVC, AV1 or PyroWave. The host turns HDR on for its virtual display; Windows' Use HDR switch doesn't matter.
- Start the game inside the HDR stream. A game already running before the session was HDR needs a restart.
The layer skips a few games with kernel anti-cheat, such as Counter-Strike 2 and Apex Legends. To keep it out of another game, set DISABLE_PF_VKHDR=1 in that game's environment, or list the executable in PF_VKHDR_EXCLUDE.
Windows Auto HDR doesn't help: it works on DirectX 11 and 12 games only.
Full steps: HDR docs. How the layer works: a Vulkan layer that brings HDR back. Confirm the cause on your PC: DirectX HDR works, Vulkan HDR doesn't.