Thanks for the information. I will give that a try. I have already installed bifrost awhile ago but haven't played with it. I do something similar with tcomb but since it doesn't have an alt clip parameter I do this:

s1d1=avisource(1d comb output from ld-decode)

s1d2=avisource(2d comb output from ld-decode)

s1d3=s1d1.tcomb(2,4,5,5,6,false,12)

s1d3mask=s1d1.tcomb(2,4,5,5,6,true,12).greyscale().invert()

s1adapt=overlay(s1d3,s1d2,mask=s1d3mask,mode="blend",opacity=1)

It's kind of a hack but works like it should.

So with bifrost it might be best to use a clip which has already been 2d combed? If so, a person could use tcomb/a good 2d comb to eliminate dot crawl and then bifrost to eliminate rainbowing.