Deinterlacing causes duplicate frames

[billr55829350]

I have a peculiar problem.  I'm working on a set of 5 old standard-definition, interlaced videos.  Of these, 3 exhibit this odd behavior.  When I de-interlace these 3 videos, the software introduces duplicate frames, at a rate of approx 1 frame for every 4.  The videos are at a frame rate of 29.97.  This is suspect to me, because the duplicate frame rate occurs if you convert from 23.976 to 29.97, so it makes me wonder.

The duplicate frame behavior occurs with Premier, After Effects, Handbrake, and Topaz Video Enhance AI.  It only occurs with these 3, I've never seen this happen before with many other standard-def interlaced videos I've processed.

Have you ever encountered this before?  Is there a way to deinterlace a video and not have this happen?
This is going to cost me a large number of hours to remove the duplicate frames, and I would love to know how to avoid this in the future.

[R Neil Haugen]

There's something called "cadence" in deinterlacing some files ... based on pull-down ratios.

Is your media 23.976 or 29.97?

Let us know what your current sequence settings are, what the media originally was, and how you're changing that. That would be very helpful!

You can get proper pull-down cadences in Premiere, however, if that isn't working, try After Effects, which has more robust tools for checking and changing cadences for pull-downs.

Neil

[billr55829350]

My post is a bit muddle, sorry.

The interlaced video is 29.97 fps.  I am applying Topaz AI to upscale the video to HD.  In some cases, I bring the video directly into Topaz; in other cases I will process it with Handbrake to de-interlace it, or use After Effects.  I have just become aware of this duplicate frame issue occuring on 3 out of the 5 videos I'm working on.  The duplicate frames appear when I de-interlace with any of these pieces of software: Premier, After Effects, Handbrake, Topaz AI.

I'm not familiar with cadence or pull-down ratios, and will begin researching those topics.  Thank you for any advice you have.

[billr55829350]

Another clarification: I'm rendering to 29.97 fps.  I'm not attempting to convert the frame rate of the source.

[R Neil Haugen]

I would suggest asking about this on the After Effects forum, and looking for help on pull-down situations. There are tools in Ae for fixing pull-down issues.

"Pull-down" is what happens when interlaced material is made into progressive with certain changes in frame-rate. You get 3:2 (or is it 2:3) pull down.

Neil