Frame Rate Conversion as ProRes - what has changed, please?

[neil wilkes]

Until very recently, changing the frame rate from 25 to 24 was an easy thing.

I simply selected DnxHD and went for it. Since things have changed with DnxHD and ProRes in Premiere, the conversion process seems to have become all but impossible as I get a really irritating little stutter - almost as if a frame has been dropped somewhere, and it is making the process next to impossible.

There are 3 modes: Frame Sampling, Frame Blending & Optical Flow and each has their problems on this particular footage. FB causes some of the people to appear as if they have 4 legs each. The ghosting is all over the place & unacceptable. Optical Flow is exactly the opposite of what it claims - it looks terrible, and Frame Sampling is causing not only the stuttering effect vbut has an almost complete image break-up on one particular scene.

So the BIG question is - how can I get this frame rate conversion done without changing the run time duration? Yes, I can interpret the footage as 24 instead of 25, and create a new sequence & yes I understand this is how it is normally done - but that adds 4% to the run time and alters the audio speed & pitch, which is unacceptable.

I have also tried Topaz Labs Video tool, using the Cronos AI which is designed for the job and it looks fantastic - but the result plays out either 18 seconds too quickly (converting to 24 fps) or 8 seconds too quickly (converting to 23.976 fps) so that's no use either.

I feel a lot like Edison when he was trying to make an incandescant light bulb and famously said he had found 'thousands of ways not to make one' (or something along those lines, anyway) and have put so far last week 100 hours & $800 cash and still all I have done is found ways not to do this.

What irks me more than almost anything though is that this process used to work right up until very recently, so what has changed to cause this to start happening, please?

Finally - does anyone have any suggestions? FS looks the best apart from this seemingly 'dropped' frame every so often and at least it maintains the correct run time. I wonder if running a Topaz Repair, or a slo-mo would fix the issue?

[Michael Grenadier]

sorry if you already understand this, but it's not clear from your post...  Changing the speed of a clip without changing the duration requires you use one of the 3 frame interpolation options...  The first 2 will NOT create new frames and definitely will be visible.  Optical Flow can produce great results but it's very dependent on the amount of motion between frames as it's trying to create new frames...    Sometimes the amount of movement is too extreme for this process to work.  If you have an example of this working previously with a shot that will no longer work, post it here.  If you're using different shots, you may just be facing the limitations of the technology.    

You might try After Effects which may do a better job.  I think AE calls optical flow, pixel motion...  I've sometimes used it when I have to apply both a speed adjustment and image stabilization...   Not sure it was any better than Premiere but it does give you more control over image stabilization.  

[neil wilkes]

(POSTED IN ERROR - PLEASE DELETE)

[neil wilkes]

sorry if you already understand this, but it's not clear from your post...  Changing the speed of a clip without changing the duration requires you use one of the 3 frame interpolation options...  The first 2 will NOT create new frames and definitely will be visible.  Optical Flow can produce great results but it's very dependent on the amount of motion between frames as it's trying to create new frames...    Sometimes the amount of movement is too extreme for this process to work.  If you have an example of this working previously with a shot that will no longer work, post it here.  If you're using different shots, you may just be facing the limitations of the technology.    

You might try After Effects which may do a better job.  I think AE calls optical flow, pixel motion...  I've sometimes used it when I have to apply both a speed adjustment and image stabilization...   Not sure it was any better than Premiere but it does give you more control over image stabilization.  

By @Michael Grenadier

Sadly I do understand this.

What I do't get is why the artifacts are suddenly much more visible than previously. Optical Flow looks horrendous - it simply cannot do the job at all, and neither FS or FB are in any way acceptable as they sit so the way I see it I have 2 choices, neither of which are great.

1. Import the source, Interpret as 24fps and render. This increases the run time by 4% but I now have the right frame rate & the conversion is clean. It's a concert film though, so cannot leave it like this (or futz with the sound) so I now need to slomo this back down to the right speed, and have either Twixtor or else Topaz Video Enhance AI's CRONOS mode. 

2. Take the stuttery hit in Frame Sampling conversion & repair that with Topaz Video Enhance AI.

Testing both options to see what looks the best

Secondly - where do I find those settings in AE, please? I am literally clueless with that tool