Advice on odd telecine pattern

[Steen4]

I've been playing around in Virtualdub with a public-domain Betty Boop cartoon that I recorded long ago. The telecine pattern, however, is unusual: 3 progressive frames followed by 3 interlaced frames. Telecide will get me to a progressive stream of 5 unique frames and the sixth frame is a repeat of the 5th frame. Can I get this back to 23.976, or would I be better off simply using telecide on it and coding it as 29.97 progressive?

[manono]

Hi-

If it's as you described (Telecide alone produces 5 unique frames and one duplicate frame in every sequence of 6 frames), then you add in Decimate(6) to bring it back down to 24.975fps. Your source was converted from PAL 25fps to NTSC 29.97fps, and that's one of the ways it's done.

You can't just Decimate(5) to bring it down to 23.976fps. In addition to removing the dupe frames, that will also remove one unique frame every second and make a slight stutter or jerk in the playback every second. Nor do you want to encode it as progressive 29.97fps. That duplicate frame every 6 frames will also give the video stuttery playback.

I'm assuming you're using an AviSynth script to frameserve into VDub. It's just about the only way to do this correctly.