Quote:
Originally Posted by augman000
By the way: I am really liking xvc. It is beating AV1, x265, and VP9 in my tests with PSNR and SSIM scores. I'd like to measure VMAF as well but I have been unsuccessful in all my attempts to compile a working win64/win32 binary.
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SSIM and especially PSNR are not very good metrics, particularly with advanced new codecs. Or anything that is psychovisually tuned.
VMAF is probably the least-bad objective metric we have, but still has some pretty big limitations and blind spots. It wasn't tested with anything >1080p or below something like 300 Kbps. SDR 8-bit only. A quite weak temporal comparison module. And it was trained on just x264, and so doesn't know what to do with new types of artifacts AV1 and HEVC can have.
Plus there's the whole question of how you aggragate individual frame scores into a clip score. Just the mean of the metrics can't discriminate between content that is consistently mediocre versus oscillating between terrible and pristine.
With a new codec, actually looking at it is really the only thing that can give a better than a rough ballpark. Certainly a difference of less than 5 VMAF, 4 PSDR dB, and 3 SSIM dB should be verified visually.