Star, could you post the output when you run `vainfo` in the terminal? AFAIK the ffmpeg va-api backend can be used for both hardware and software decoding. That means if your GPU decoder doesn't support a certain codec, ffmpeg will just decode things in software, upload to VRAM and still share the result with firefox via dmabuf. I do not know if there's a clear hint when a certain format is decoded in hardware or not - but Martin should know :)
Bug 1668735 Comment 3 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
Star, could you post the output of when you run `vainfo` in the terminal? AFAIK the ffmpeg va-api backend can be used for both hardware and software decoding. That means if your GPU decoder doesn't support a certain codec, ffmpeg will just decode things in software, upload to VRAM and still share the result with firefox via dmabuf. I do not know if there's a clear hint when a certain format is decoded in hardware or not - but Martin should know :)