OK, new development for this mysterious HEVC Extension.
I finally made it work ! HEVC Extension does support hardware decoding, in a way that's really hard to know.
Yup, the uncheck "Hardware" setting is normal, because the decoder was not designed by a particular hardware maker like NVIDIA. So my point in the last post is not valid.
First, the real solution for me: Uninstall Nvidia's Game Ready driver and install the Studio driver.
There is definitely something that helps hardware decoding with the Studio driver, because I had been trying for 2 days with the Game Ready driver and the hardware decoding never worked in VR, but after I completely uninstalled the Game Ready Driver then install the Studio driver fresh, in about 20 minutes the hardware decoding suddenly worked, and it kept working ever since.
For your machine with Nvidia GPU, to see if hardware decoding works, you configure LAV Video decoder to use "NVIDIA CUVID (old)" as the hardware decoder. In DeoVR you turn on the "DirectShow" in settings while playing a HEVC video. Now check the GPU usage in Task Manager, if "Video Decode" is more than 0%, your hardware decoding is working and HEVC will be able to handle 7k or 8k videos. Once the good old CUVID works, you can turn off the "DirectShow" setting in DeoVR and enjoy the shows.
If it doesn't work, you need to check the following:
- Are you using latest Nvidia STUDIO driver?
- Did you install latest 64BIT HEVC Extension?
- Does hardware decoding in other media players ( PotPlayer, VLC, MPC-HC...etc) work?
- Did you install the latest 64bit LAV filters?
- Use DXVA checker to see the settings of your HEVC extension.
( I don't own AMD video cards, so I cannot say anything about it. By the way, I am surprised that the decoder can only handle videos up to 8k. What a big limitation ! The future of VR videos should be 12k or even 16k. This Nvidia decoder is seriously under-powered. )
Note: Some mp4 videos might have problems like showing only the left half or no hardware decoding. You can fix it by muxxing it to MKV using the excellent free MKVtoolNix.