[D3D11VA] Request to enable DXVA HEVC YUV444 support

mpv Information

Other Information

- Windows version: Windows 11 25H2
- GPU model, driver and version: RTX 2080
- Source of mpv:
- Latest known working version: NIL
- Issue started after the following happened:

Reproduction Steps

Play a HEVC YUV 444 video (10 bit for example). Notice that it is software decoded.

Expected Behavior

Hardware decoding works.

Actual Behavior

Hardware decoding doesn't work.

As @kasper93 explained in https://github.com/mpv-player/mpv/issues/18172#issuecomment-4793213696 :

444 HEVC is supported in official documentation now https://learn.microsoft.com/en-us/windows-hardware/drivers/ddi/dxva/ns-dxva-dxva_picparams_hevc_rangeext

I could implement this official extension, but I don't have hardware to test this on, so I won't.

I am willing to try and implement the fix, allowing MPV to utilise D3D11VA's HEVC YUV444 hardware decoder. I would like to get the HEVC 444 8b, 10b and 12b variants all working.

I would greatly appreciate if any MPV developer can provide some guidance, including which files I should look at/edit.

If any developer wants to help and implement the fix but lacks the hardware to test it on, I am more than happy to help run the tests. I have an RTX 2080.

Log File

output_sanitized.txt

Sample Files

No response

I carefully read all instruction and confirm that I did the following:

• I tested and confirmed that the issue exists with the latest release version or newer.
• I provided all required information including system and mpv version.
• I produced the log file with the exact same set of files, parameters, and conditions used in "Reproduction Steps", with the addition of --log-file=output.txt.
• I produced the log file while the behaviors described in "Actual Behavior" were actively observed.
• I attached the full, untruncated log file.
• I attached the backtrace in the case of a crash.

No source file or test is named. Start by locating mpv's D3D11VA HEVC decoding path and reviewing the DXVA HEVC range-extension documentation referenced in the issue. Validate hardware decoding for HEVC YUV444 8-bit, 10-bit, and 12-bit samples on the reported RTX 2080, with the attached log as the baseline.