Variable frame rate issue (from DVD) when upscaling

I want to upscale some Star Trek Voyager and Deep Space nine episodes using Topaz video AI but have run into the same problem other people have had. The NTSC raw DVD SD files are variable frame rate. Some sections of each episode are at 23.976 and others (the CGI sections) are 29.97 frame rate. For example the overall frame rate of one episode might be 24.66.
This creates a problem for smooth playback of all parts of an episode, and is the same when upscaled…

I have got hold of some other Topaz upscales of these shows other people have done and they have somehow managed to make a whole episode 23.976 frame rate. They look good, - no judder etc.

Does anyone have any ideas of the best way to address this?

I think the best way would be to get the variable frame rate SD source file (ripped from the DVD) transposed to 23.976 instead of variable frame rate, but how do you do that for mixed footage at different frame rates?

This is a long shot and I’m probably dreaming, but is there any kind of program that could scan a video file with mixed 23.976 and 29.97 footage, and identify the 29.97 portions and then convert those parts 23.976 without quality loss?, and leave the parts that were originally 23.976 untouched.

I’m guess that a long shot, but wanted to ask. Or are there other good days to sort this out.

If anyone is familiar with this problem and has a way around it, any advice would be really appreciated.

Pretty sure I’ve seen two blogs about doing this to this exact show and explaining how they deal with that frame rate issue. It shouldn’t be too hard to find them.

I agree with @ForSerious and would recommend looking through this chapter of’s series about upscaling the Deep Space 9 DVDs.

We’re working to improve the VFR experience within the app, but it seems to be an issue that can be seen across multiple different video processing tools specifically when working with interlaced content that flips between 23.976 and 29.97fps.