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[Help] 60i (29.976) to 24 (23.976) Methods
#1
Hello Fan Res.

Its me again asking for all your help with a conversion method Smile
It does not directly connect to a fan project I'm working on, but could come handy for that in the future.

Long story short, I was doing a live event video shoot as a favor for some friends and one of the cameras was recorded in 60i (29.976)!
The rest and delivery format is 24p (23.976).

Does anybody know of the best method to convert 60i to 24p?
I was following some Avisynth scripts up when searching on google but all led to dead ends Sad

Thanks once again for your time.

(Im a Premiere user and use Avisynth + if that helps)
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#2
When you cut, just make your main sequence in 24p and import all your 60i footage, Premiere will take care of it automatically (it will use a simple resampling, choosing the nearest frame/field from the 60i stream for each frame). Now, it should automatically detect the 60i, but if it doesn't, you can do "Interpret Footage" with a right click in Premiere and set the field order.

Now, naturally that will introduce a very slight amount of jerkiness, as the frametimes of the 60i stream dont fall exactly on the frametimes of the 24p stream, but it's your bet either way. And in most scenarios its unnoticeable.

You could slightly alleviate it with Frame Blending (blending together the two nearest frames, each's opacity weighted by how close it is), but I absolutely despise the look of it. Whenever you stop the video or look closely, you will clearly see two images overlaid over each other, it just looks terrible and screams "amateur" to me. Tongue

The only other way, if you wanted it to be ... more fluid, so to speak ... would be to use time interpolation for the framerate change. I don't recommend it though, because it is A. slow and B. introduces lots of artifacts typically. I *always* opt for the frame sampling method for that reason. I just prefer the image to look professional and clean and the interpolation artifacts really mess with that. The only case where I would consider interpolation is in a scene that has absolutely minimal and only slow motion in it, then the interpolation tends to work without noticeable problems.

If you want to try out yourself, you can just set up the project like I mentioned, drop the footage in your timeline, then right click on the clip in the timeline and there is something called "Time Interpolation" I believe, which goes to a dropdown showing you the options "Frame Sampling" (Default), "Frame Blending" and "Optical Flow". Frame Sampling is my preferred one. Frame Blending I explained above. Optical Flow is the one that does an interpolation (though there might be ways to do it outside of Premiere that are better, I am not sure).

Perhaps important note: Since your source footage is interlaced, you may consider deinterlacing outside of Premiere to create a lossless or very high-bitrate 60p stream first. Premiere does automatically deinterlace, but it doesn't do so with very advanced algorithms. I will say, it will probably look good either way, but if it's some professional project or something and you want every last bit of quality squeezed out of it, external deinterlacing is something you could do. Though the good methods also tend to be rather slow, and the intermediate files resulting from that will be rather big. Personally, I wouldn't bother, but wanted to mention it
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Thanks given by: CSchmidlapp
#3
I think just dropping it on the timeline is the way to go. Cheers Tom.
The footage is a wide shot and will be used a couple of times to cover my camera adjustments on other shots.

On a side note, all the other footage is HDV with 24p contained in a 60i stream. I normally do the pulldown before entering Premiere to lossless intermediate with this kind of footage (sometime with a light clean up). Do you think its worth letting Premiere do the pulldown?

(I shot on some old tape based HV20 and HV30 camcorders i had lying around in-case I needed a tape DV/HDV capture device Smile)
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Thanks given by: PDB
#4
I'd recommend Twixtor. It's a pretty nice plug-in for After Effects that I use when I need a framerate downconversion.
It's usually pretty seamless but can also look atrocious when you go the opposite way.

Edit: Didn't see that it was actually 23.97 contained in interlaced HDV. So yeah, it'd be seamless for sure without any filter applied to it.
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Thanks given by: CSchmidlapp
#5
(2018-09-02, 05:59 PM)ilovewaterslides Wrote: I'd recommend Twixtor. It's a pretty nice plug-in for After Effects that I use when I need a framerate downconversion.
It's usually pretty seamless but can also look atrocious when you go the opposite way.

Edit: Didn't see that it was actually 23.97 contained in interlaced HDV. So yeah, it'd be seamless for sure without any filter applied to it.

Sorry, most of the footage is 23.976 inside 60i. I captured a couple of tapes at 60i without the 24p setting applied.
Ive amended my post to reflect this Smile
And will have a look at Twixtor, it rings a bell.
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#6
Twixtor is a motion interpolator. Better than Premiere's internal one for sure, but I personally would only use interpolation in emergencies.

As for the pulldown: This 24p in 60i stream is kind of a new thing and I haven't read up on the Adobe documentation of it, if any exists. With that said, I see absolutely no reason in theory why Premiere shouldn't be able to perfectly handle this, if it has a function for it. As far as I understand it, the 24p in 60i thing is just a kind of trickery anyway to make some hardware accept the signal or w/e. But I haven't personally ever used it so I can't be of much better help sadly. Maybe Adobe's documentation has a better answer i dunno.
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