Apply a Filter at Regular Intervals

[Monkeylord]

I have a clip where when I IVTC it the chroma gets messed up every 4th frame. For some reason it includes the chroma from the previous frame.

I added the following line to my script;

mergechroma(selectevery(1,1))

This fixes the frames where the errant chroma is introduced, but obviously screws up all the previously good ones.

What's my best method of applying the above line but tell it to only occur every 4th frame?

I messed around with the "selectevery" portion of the line, but the slightest change would introduce chroma from all manner of frames.


I really need to find an idiots guide to avisynth filter use/syntax, lol.