[FFmpeg-devel] [PATCH 1/3] avcodec/dxva2_hevc: add support for parsing HEVC Range Extension data

[Steve Lhomme]

On 2020-03-15 13:05, Hendrik Leppkes wrote:
> On Sun, Mar 15, 2020 at 8:12 AM Steve Lhomme <robux4 at ycbcr.xyz> wrote:
>>> Where is this struct specified? I don't see it in the latest released
>>> Windows SDK.
>>
>> It is not. It is reversed engineered from the existing structure and wild guessing based on the HEVC Range Extension specs. The bits/fields are in the same order as the specs. Then I tested some GUIDs that output non 4:2:0 pixel formats on an Intel GPU that is known to decoder HEVC Range Extension.
>>
>> Apparently NVIDIA doesn't provide DXVA GUIDs that output non 4:2:0 pixel formats on GPUs that supposedly decode HEVC 444 (likley nvdec only). AMD doesn't have such GPUs AFAIK.
>>
>> So for now it's Intel only.
> 
> That seems very hackish for something thats otherwise cleanly based on
> official specifications only.  Maybe try to get them to release specs
> for this instead?

 From what I understand only MS publishes DXVA specs and it seems they 
have no intention on doing one for HEVC Range Extension. That may be why 
NVIDIA has not implemented it. I don't know if Intel is planning to 
release a documentation.