似乎HEVC在帶有最新WhateverGreen / Shiki的AMD GPU（無iGPUless）的10.15.2中無法正常工作。自從beta以來，這種情況以前從未發生過，並且許多用戶都在報告問題。
https://www.tonymacx86.com/threads/catalina-10-15-2- update-lost-hevc-h265-acceleration.288563 /
Here is my test, i can confirm that there is NO FREEZE or PANIC so far:
- add boot-args:
shikigva=32 shiki-id=Mac-7BA5B2D9E42DDD94on top of my iMac19,2 SMBIOS, make sure everything is using AMD GPU. ( i use these boot-args just for testing AMD GPU, so that the iGPU is not used during my test )
- use QuickTime to record my 4k screen, i did a 4m47s recording
- use QuickTime to save as 1080p in HEVC format, it takes less than 4mins to finish the encoding.
- during recording and encoding, the CPU usage is around 3%, it is pretty amazing.
- play back the recoded 4k video and encoded 1080p HEVC video using QuickTime and mpv (installed via
brew install --HEAD mpv), again only 3% CPU usage.
- play back jellyfish-120-mbps-4k-uhd-hevc-10bit.mkv using mpv multiple times during screen recording, only 3% CPU usage.
i5-8400, RX 470, macOS 10.15.2, opencore-version REL-054-2019-12-13