Non-monotonic behaviour in AV2 when using Fixed QPs since avm-v1.0
Edit: Updated title from Non-monotonic behaviour in AV2 for low-QPs to Non-monotonic behaviour in AV2 when using Fixed QPs since AVM-v1.0, as we have this bug of non-monotonicity at certain intermediate QPs in all ranges.
What version / commit were you testing with?
All versions starting research v1 (git describe can produce this info.)
What steps will reproduce the problem?
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Encode the video at different QPs in All-Intra mode at any CPU presets. Typically observed with QP<30, or QP>220
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Check the (R,D) points, and we can observe non-monotonic behaviour
What is the expected output? Monotonic behaviour when changing QP (QP increases, (R,D) decreases)
I have only tested at 480x270p resolution for now, but I do not think that matters. But even then, the non-monotonicity seems to be quite bad, irrespective of {cpu-preset, chroma subsampling}.
Example CLI:
avmenc --cpu-used=0 --passes=1 --end-usage=q --kf-min-dist=0 --kf-max-dist=0 --use-fixed-qp-offsets=1 --deltaq-mode=0 --enable-tpl-model=0 --enable-keyframe-filtering=0 --obu --psnr=1 --enable-intrabc-ext=1 --cpu-used=0 --qp=242 --limit=15 -o NocturneRoom_3840x2160_60fps_hdr10.y4m-242-15f-av2-basic.obu NocturneRoom_3840x2160_60fps_hdr10.y4m-270p.y4m
