IVTC an odd telecine pattern

[ChiDragon]

Like the title says, I've run into a weird telecine pattern that I'm trying to IVTC. It's in a NTSC DVB "capture" of a Law & Order episode. The strangest thing is that the first half of the ep or so is normal, then after the midway commercial break the weirdness starts. I've seen this in a number of eps now (and in all airings of those eps), and so far I've tried to deal with it using TDecimate's hybrid blending option, but I was wondering if anyone had encountered this sort of thing before and/or could think of a better way to deal with it.

The pattern is a couple of normal 5-frame sets (4 new, 1 dup) followed by a 6-frame set (5 new, 1 dup), and then back to more 5-frame sets, then a 6, etc. I don't understand how a film source could give a pattern like that... TDecimate can deal with it without a problem for a number of cycles - every few cycles the placement of the duplicate moves from first position, to 2nd, etc. - until it reaches the one where all 5 frames in a cycle are new. That's where the blending kicks in, which is preferable to just dropping one of the new frames of course, but not ideal.

Anyway, here's a clip to work with:
http://rapidshare.de/files/34043967/weirdtc.mpg.html

Thoughts?

[Guest]

You can try FDecimate(23.976).

You may have to play around to find the correct base frame rate.

You might have to resort to MultiDecimate. cycle-based naive: cycle 30, remove 6 works good for me on this clip.

But I think TDecimate can do N in M decimation also. Try it with remove 6 per 30.

[ChiDragon]

Thanks for the response. I tried 6 in 30 with TDecimate but every 4-5 cycles of 30 it drops a non-dupe frame.

I went through a bunch of frames and figured it out as 25 dupes per 130 frames though, which reduces to 5 in 26 (24.207 fps). This seems to do the job perfectly, knock on wood. Hopefully the other eps with this problem use the same values. Using this on the whole episode leaves duplicates in the 23.976 section of the ep, of course. I guess I'll have to use splice and AssumeFPS to lower the rate of the second half.

I'm curious why part of the eps would have such an odd frame rate though, can you think of any reason?

Thanks again for your help.