[sh0dan]

I had a few concepts in mind for "extreme" compression optimizitation:

Case 1:
Do an ordinary two-pass encode. Compare the output to the source. If SSIM difference is big, do additional filtering on these frames for a third/fourth pass.

Case 2:
Compare original frame to a blurred version. This should give a fairly good idea on the amount of high-frequency (spatial) detail level. This value could be used for setting threshold for a filter.



PS: There is also conditional functions for retrieving Y,U & V-plane only SSIM difference.

SSIM_Y(clip a, clip b)
SSIM_U(clip a, clip b)
SSIM_V(clip a, clip b)
SSIM_AVG(clip a, clip b) = 0.8 * SSIM_Y(a,b) + 0.1 * SSIM_U(a,b) + 0.1 * SSIM_V(a,b)