Best AVISynth or VDub filter to remove duplicate frames?

[LisaB]

I have a 29.97 fps MPEG1 source that has a very odd five-frame pattern. It has 3 progressive frames followed by 2 progressive (but blurry in the motion parts) frames. What makes it odd is that the 2 blurry frames in the cycle are identical.

From everything I have read, I assume that this clip started as FILM, was telecined to 29.97, was badly converted back to film by just deleting one of the interlaced frames in each group, was deinterlaced (making the remaining interlaced frame motion blurred), and was finally badly reconverted to 29.97 by duplicating the blurry frames. This is the only scenario I can guess that would cause what I see. Is this reasonable?

Given this, it seems the best I can do to salvage this clip is to delete the duplicate frames. Can anyone suggest the best AVISynth or VDub filter to do this? I plan to re-encode in TMPGEnc.

[sterno]

It may also be that it was just deinterlaced, the two blurred frames would look very similar but wouldn't be identical. However, if they really are identical (or close enough) you can try using decomb with avisynth and using decimate(cycle=5).