Mixing Clips

[WarpEnterprises]

How can I mix (blend) 2 clips (same resolution & fps) in Avisynth?

[Wilbert]

See http://www.videotools.net/doc/reference.htm and the dissolve filter. Something like:

Dissolve(clip1,clip2,overlap)

with overlap the number of overlapped frames.

[WarpEnterprises]

Thanks, but I am searching for a more specific way to blend.
I want to blend clip1 with some FIXED percentage with clip2 the whole duration of the clips. This can't be tricked with dissolve and I found no other way. It should be like some complement to Substract.
Any hints?

btw I have made a workaround ( S = A+B = subtract(A,-B) ) , but I think that there is a loss because of the many integer operations:
A=trim(0,0)
B=trim(20,0)
S=Subtract(levels(A, 0, 1, 255, 64, 192) , levels(B, 0, 1, 255, 192, 64))