I'm using an Intel Mac (Ice Lake chipset), and according to Intel, my GPU supports hardware decoding of MPEG-2, VC-1, and VP9 using Quick Sync (VideoToolbox on MacOS).

Playing back H.264 and HEVC shows that VideoToolbox (hardware decoding) is being used, but playing back MPEG-2, VC-1, and VP9 says it's not using hardware decoding, and CPU usage is significantly higher, and video playback drops frames.

Any idea why hardware decoding is only working for H.264 and HEVC, but nothing else?