How do I apply avisynth filters in zone/segments?

[poisondeathray]

How do I apply a filter for certain frames, but not others?

An example might be a clip with 10000 frames. A dark scene with a single light source causes banding in frames 2000-3000. I might want to apply a filter on, something like GradFun2db, but not expose the rest of the film to it. - You get the general idea...

I'm looking for the generic syntax on how you might do this (in general, doesn't have to be that specific filter)

I know you could also encode it in segments, and even encode using quantizer zones at the encoder level, but I'm trying to learn about avisynth processing, and there's probably an easy yet elegant script that my Google search hasn't come up with yet.

Thanks for any comments

[guns1inger]

Trim lets you segment a video. e.g.

clip=AviSource(clip.avi)
clip1=Trim(clip, 0, 1999)
clip2=Trim(clip, 2000, 3000).Tweak(sat=0.5)
clip3=Trim(clip, 3001, 0)
final_clip=clip1 + clip2 + clip3
ConvertYUY(final_clip)

Breaks the source clip into parts, reduces the saturation of the second part, recombines them and does a colourspace change to the entire clip.

[poisondeathray]

Thanks, I'll try it out

Cheers