It exists only as a patch from Intel (https://github.com/intel/cartwheel-ffmpeg/blob/master/patches/0071-lavc-vaapi-support-av1-encode.patch https://github.com/

It exists only as a patch from Intel (https://github.com/intel/cartwheel-ffmpeg/blob/master/patches/0071-lavc-vaapi-support-av1-encode.patch https://github.com/intel/cartwheel-ffmpeg/blob/master/patche...) but I haven't seen any efforts to upstream it yet.