Add support for hevc_d3d11va Decoder

[aizizai]

Hello, Currently, D3D11VA is enabled, but it seems that the hevc_d3d11va decoder is not enabled yet. Can you add this? Thank you very much.

[Sibras]

The d3d11va hwaccel should be enabled which can be used however there currently isnt a standalone hevc_d3d11va_decoder in ffmpeg, so theres nothing more to enable

[aizizai]

But " .name = "hevc_d3d11va" is defined in ffmpeg/libavcodec/dxva2_hevc.c, is this the decoder?

Additionally, here is my debugging output. As you can see, d3d11va is supported, but hevc_d3d11va is not recognized. If I want to use d3d11va for hardware-accelerated decoding, how should I proceed? Thank you.

Supported hardware decoders on this system:

cuda (Not supported)
vaapi (Not supported)
dxva2 (Supported)
qsv (Supported)
d3d11va (Supported)
opencl (Supported)
vulkan (Supported)
d3d12va (Supported)
Hardware decoder not found: hevc_d3d11va

Successfully opened codec: hevc_qsv

[Sibras]

If your using ffmpeg cli program (which you havnt specified what your using) then you just need to pass -hwaccel d3d11va to use the supported d3d11va decoder (no need to directly specify a decoder)

The hwaccel system replaces the older explicit decoder system so hwaccel decoders do not show up in the codec list (only entries in libavcodec/allcodecs.c will show up)

If you want to prove to yourself a hardware decoder is in use then you can run./ffmpeg.exe -hwaccel d3d11va -threads 1 -i test.mp4 -f null - -benchmark then remove the hwaccel bit and compare the speed difference