Is it possible to get FFmpeg to use hardware acceleration for HEVC transcoding on macOS?

On macOPS there’s videotoolbox.

Check this out for the encoder options:

ffmpeg -hide_banner -h encoder=hevc_videotoolbox

Output:

Supported pixel formats: videotoolbox_vld nv12 yuv420p
hevc_videotoolbox AVOptions:
  -profile           <int>        E..V.... Profile (from 0 to 3) (default 0)
     main                         E..V.... Main Profile
     main10                       E..V.... Main10 Profile
  -allow_sw          <boolean>    E..V.... Allow software encoding (default false)
  -realtime          <boolean>    E..V.... Hint that encoding should happen in real-time if not faster (e.g. capturing from camera). (default false)
  -frames_before     <boolean>    E..V.... Other frames will come before the frames in this session. This helps smooth concatenation issues. (default false)
  -frames_after      <boolean>    E..V.... Other frames will come after the frames in this session. This helps smooth concatenation issues. (default false)

Maybe you can test with that, if you have a recent Mac.

More on videotoolbox: https://developer.apple.com/documentation/videotoolbox

As you can see, it taps into the hardware-based encoders available on macOS, offering a unified API for video encoding across multiple abstractions (Intel's QuickSync on supported Intel IGPs, etc).

Grab a build here: https://evermeet.cx/ffmpeg/