Comment # 3 on bug 91281 from Andy Furniss

I know what causes this now.

It's the get_cpb_num case statement in radeon_vce.c.

It only handles up to 51 and defaults to 42.

ffmpeg lucked into working because it calls 51 when it should really be 52.

gstreamer vaapi calls correctly so only > 2160p30 fails as 52 gets default.

gstreamer omx always fails because it seems to max at 42.