Thanks for your work, why is my kvd negative？

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No description provided.

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{
"temporal_clip_consistency": 0.9431219907660336,
"temporal_motion_smoothness": 0.9815742254305226,
"imaging_quality": 59.6201134467125,
"fvd": 2233.626708984375,
"kvd": -68.35126439144739
}