AV1_AMF encoded video giving incorrect VMAF scores

[Immrspy]

Because AV1_AMF encodes to an even 64x16 grid, padding the rest with black pixels, video needs to be cropped before an accurate VMAF score can be achieved. For 1080p video, this means cropping off the bottom two rows (the video is 1920x1082, with 2 rows of null information). Without cropping off the bottom two rows, VMAF scores are calculated using scaled video, which gives a value anywhere from the 70s to the 50s when the true value should be in the 90s. To fix this error, the ffmpeg command needs to look like this:

ffmpeg -i encoded_amf.mkv -i reference.mp4 -lavfi "[0:v]crop=1920:1080:0:0[encoded_amf];[encoded_amf][1:v]libvmaf" -f null -

Adding a crop to remove the bottom two lines before it reaches VMAF.

Because AMD's AV1 encoder is starting to become more popular, and because this tool is really helpful in comparing different encoding methods, could there be some workaround to detect 1082p video and crop it down to 1080p?

This issue is not present at 1440p and 2160p (4K) because those resolutions are a multiple of a 64x16 aspect ratio.