How can av1_amf be used with ffmpeg as stated on the ffmpeg wiki?
I have already tried asking on the ffmpeg user mailing list, but I haven't got a response.
You need to specify -c:v av1_amf in your command.
So a very basic version might look like:
ffmpeg -i input.mp4 -c:v av1_amf output.mp4
But be aware, there is an issue with amf's recognition of quality settings in the current implementation.