ab-av1: VMAF values incorrect by 20 to 30

I am consistently getting VMAF results that are 20 to 30 less than if I ran VMAF or libvmaf directly on the same files. This is true for all of the commands, i.e., trying to use crf-search or auto-encode won’t work correctly because it can’t find the right vmaf (unless i set minimum <70).

Example results: ab-av1:

Z:\Files\Rips\Muxing>ab-av1 vmaf --reference "source_snip.mkv" --distorted "RF22_snip.mkv" --vmaf model="path=vmaf_v0.6.1.json"
(vmaf 29 fps, eta 0s)67.469444

libvmaf:

Z:\Files\Rips\Muxing>ffmpeg -i "RF22_snip.mkv" -i "source_snip.mkv" -lavfi libvmaf="n_threads=6" -f null -
[Parsed_libvmaf_0 @ 0000020d93a4bf80] VMAF score: 93.391178

Not sure if this might be a versioning thing or if I can resolve?

Running on windows vm at the moment with:

• ab-av1 0.4.3
• ffmpeg 2022-10-30-git-ed5a438f05-full_build
• vmaf 2.3.1
• svt-av1 v1.3.0
• opus 0.2-3-gf5f571b (libopus 1.3)