Background I can’t believe how much time I spent on debugging this. This story begins with a new AMD graphics card. After installing the AMD RX6000 series graphics card and the amdgpu driver, and setting all the required Firefox configs, I open a youtube video at 4k 60fps on Firefox and expect to enjoy av1 hardware accelerated decoding. Disappointingly, all I see is dropped frames.
To understand what’s wrong, I head over to about:support and observe some FEATURE_FAILURE_SOFTWARE_GL and FEATURE_FAILURE_VIDEO_DECODING_TEST_FAILED.