CalmGrain, pre-RedAverage version

function CalmGrain(clip clp,int "tstr",float "nboost",bool "soften")
{
# Requirements: RemoveGrain(SSE3).dll, FluxSmooth.dll, MaskTools2
# By yours truly, Bloax.

# ~~~~~ Wuzzis now?
# This 'should' calm grain down, whether or not it improves compressibility is a good question.
# It certainly reduces the eye-tearing effect of heavy noise compression artifacts post-encoding though. :-)
# ~~~~~

# ~~~~~ Wuzzis do now?
# "tstr" Is the strength of FluxSmoothT, higher values cause more pixels to hang around for the ride.
# Use values around 10 (for very slight reduction) to about 30-50 (or 255 if you so wish), too high values can look bad though.

# "nboost" Does something to the difference mask, not quite sure of the big, bad details.
# It does seem to improve compression by a little bit, so just leave it be.

# "soften" Is a deprecated feature (for now, at least*), it softens the picture before FluxSmooth kicks in.
# Which results in softer noise, or whatever the initial denoising catches.
# * With me, that usually means for a long, long while!

tstr = Default(tstr, 40)
nboost = Default(nboost, 1.25)
soften = Default(soften, false)

a = clp.IsYV12() ? clp : clp.ConvertToYV12()

b = a.RemoveGrain(1,-1).RemoveGrain(18,-1).RemoveGrain(17,-1)
c = Mt_MakeDiff(a,b).Mt_Expand().Tweak(Cont=nboost,Bright=(0-nboost*8))
d = soften ? a.RemoveGrain(19).FluxSmoothT(tstr) : a.FluxSmoothT(tstr)
Mt_Merge(a,d,c)
}