More Slo-Mo confusion... Where can I get a definitive answer?

Report · Oct 30, 2019

I wanted to make slow motion by taking high fps clips and slowing them down to something normal like 30 or 24 fps. Initially I did this by adjusting the speed / duration, which is the method suggested many places on the web, but Adobe appeared to add extra frames when I did this, as I show in this posting . . .

https://community.adobe.com/t5/Premiere-Pro/Playback-speed-question/m-p/10685560#M233080

...a brief synopsis is that when I used Speed/Duration to slow a 5 second 120 fps clip (600 frames) down by 4X, it did indeed slow it down by 4X but it seemed to add frames in the process because the output was 20 seconds at 60 fps (1200 frames)!

So someone suggested that I instead try Modify > Interpret Footage of the clip still in the bin. So I did that and it seemed to avoid that problem. I posted a sample to Vimeo : https://vimeo.com/369749624

... but then as I continued to research this I found a posting in this forum that seemed to say the two methods are equivalent . . .

https://community.adobe.com/t5/Premiere-Pro/Clip-speed-duration-vs-interpreting-footage-final-answer...

Specifically, "Both methods are equal as far as results when the footage speed is cut in half." . . . but as my results suggest, they are not equivalent because speed/duration adds frames, and Interpret Footage doesn't - it just plays the existing frames back at a diffeent rate. BTW, this post on Reddit also says thay are equivalent...https://www.reddit.com/r/Filmmakers/comments/7hrcja/speed_duration_vs_interpret_footage/

So I'm having trouble getting a definitive, authoritative answer here about what method to use, and when, while slowing down footage from a higher frame rate.

Thanks in advance for ultimate clarification on this topic.

Report · Oct 31, 2019

Interpret and Speed/Duration are equivalent for both quality and result.

You issue is with neither. It's with your export settings. Make sure you set your Frame rate to 30 in the export dialogue, or frames will be duplicated/added.

Report · Oct 31, 2019

Hi Peter,

I would suggest that you take your high frame rate shots and use interpret footage to set them to the same frame rate as the squence you will be editing in. This interpreted frame rate will be the baseline for what is 100% when you change the clip's speed/duration in the timeline. So if your sequence is 24fps, and your clip is interepreted to match, you'll get slow motion without any duplicate frames. But if you increase the clip speed to 500% (5*24fps=120) in the squence, it will playback in realtime (dropping 4 out of every 5 frames). You can also smoothly speed ramp between 100%-500% because you have the extra frames to work with.

If you set the speed of the clip below 100%, because you want it even slower, you will now see interpolated or repeated frames because you don't actually have any more temporal resolution to play with.

Report · Oct 31, 2019

I think it does not matter if you use interprete footage or slow down on the timeline.

I think your problem lies in the variable framerate; 119,88.