Makes differences between two videos really visible.
This can be useful to measure quality loss after encoding
# If Videos start at different frames
frameadjust=0
# Videos to compare: (v1 is original, v2 is encoded or whatever)
v1 = AviSource("original.avi",false).trim(frameadjust,0)
v2 = AviSource("encoded.avi",false)
sub = v1.subtract(v2)
substrong = sub.levels(122,1,132,0,255)
return StackVertical(StackHorizontal(v1.subtitle("original"),v2.subtitle("encoded")),StackHorizontal(sub.subtitle("Difference"),substrong.subtitle("Difference amplified")))