This is bothering me for a long time now: Why does Apple deliberately disables the the RX4xx, RX5xx capabilities to hardware encode HEVC and is using Intel Quicksync instead? Is it to make the iMacPro look better than it is? I stumbled over a thread at tony-mac where people are going a totally different road for Radeon graphics. Instead of hassling around with getting Quicksync to work, they proposed to activate the AMD hardware renderer for Polaris GPU's. I tried it out and it works...somewhat
I used a dummy kext from that tomato thread and edited it, so that it enables the AMDU7V4 IOGVACodec like on Vega cards, switched to iMacPro1,1 SMBIOS from iMac18,3, disabled the IGPU and the results were astonishing:
My 3:34min 4k50p film was rendered by FCP with HEVC in 2:34 minutes. Nearly half the time than with Quicksync! With the iMac18 SMBIOS and the "help" of Intel Quicksync it took FCP 4:41 minutes to get it done!
The problem is: As soon as the "wrong" IOGVACodec is enabled H.264 encoding leads to Mojave crashing at once (be it FCP, QuickTime or Videoproc). Watching H264 material is fine, though.
If anyone has any idea how to handle this, I would be very grateful. I would even accept Mojave using software encoding for H264 if I could keep this amazing speeds on HEVC!
BTW: Without IGPU on iMacPro1,1 SMBIOS no problem with DRM or iTunes, no need for Whatevergreen or Shiki. That is a bonus