Which frame rate for video with multiple fps?

[vidar_8659]

Hi there,

I'm just testing out premiere pro, and I'm trying to edit a video which consists of videos with 30, 60 and 240 fps videos. Most of the 240fps videos I reduce the speed to 15%. When I export the video, the settings suggest to save the video as 240fps, but if I do that, the exported video is very laggy. I guess I'm supposed to change this to 30FPS? Or maybe lower? At least when I export as 30fps, the video looks okay. The slo-mo parts is a little bit laggy, but okay. 

Any suggestions?

[R Neil Haugen]

The normal operational choice is to set the timeline to the final export result needed. And there are several different processes to put other framerates on a timeline, depending on whether you want slo-mo or 'normal' view of them. 

But timeline or sequence framerate is enough of an issue of itself, let's make that choice firs, ok? Infomation to use in the decision ...

"Movies" have traditionally been 24fps, and not 23.976 ... but most cameras 'shooting 24fps' actually produce 23.976 ... or "24/1001" ... fps.

A lot of online video is 29.97 progressive ... meaning there are precisely, and only, 29.97 frames per second, and each frame is complete top to bottom.

But if producing for US broadcast TV, you might need 29.97 interlaced upper first ... which most anyone would never ever use by choice.

"Interlaced" means there are actually two frames made, each one being every other horizontal line of pixels. "Upper first" means the first image is lines 1-3-5-7 etc, the second frame image is lines 2-4-6-8 etc. And "29.97i" is actually 59.94 images per second ... so confusingly, "29.97i" and "59.94i" are actually the same thing. (Yea, interlaced is nutso but there it it ... avoid it like the plague!)

A lot of online video, including some "modern" TV, is 29.97 progressive ... meaning there are precisely, and only, 29.97 frames per second, and each frame is complete top to bottom.

But the above is for NTSC lands like the US. Europe and many other areas are PAL ... !

So rather than 29.97, they have 25 fps! Why?

US electrical power grid is "60hz" ... 60 alternating cycles per second. Europe is 50hz per second. The idea is the image frame rate 'matches' the electrical cycle alternating rate for less flickering.

Half of 60 is somehow computed as 29.97, and half of 50 is computed as 25.

So ... what you gonnna do with that video you're making? Tell us that, and we can give you two-three possible framerates to choose from and why.

[vidar_8659]

Wow, thank you so much. This was both clearifying, but also a little confusing tbh. I live in Europe (Norway) and we have 50hz power grid, so maybe I should change my settings on my GoPro, but then the max FPS for slo-mo is 200fps. But, I guess the slo-mo speed is the same, since 200/25 = 8, and 240/30 = 8. Does it really make a difference to change from 60 to 50fps, for Europe? Or is it better for me to go with 25-50-100 etc fps?

What is the reason movies are 24fps? Isn't higher fps just better, even when not doing slo-mo?

Regarding what i'm gonna use my videos for, is both for private videos from vacations, scuba diving, motorcycle etc, but some of them will also be published to youtube (and other social media).

I guess most videoes will be a mix of normal speed, slow-motion and fast-motion. For the videos to be played in normal speed and fast motion, I currently mostly shoot in 60fps. And slo-motion in 240fps. Not sure if I should shoot the normal/fast speed in 30fps instead?

Also, videos in 30-60fps is shot in 4k, but 240fps is shot in 2k. 

As you see I'm on thin ice here, and would be nice if you can help me out here 🙂

[R Neil Haugen]

Jeg har familie i Vang i Valdres ... 😉

I would go with the mulitples of 50 then. As then, you have less computational issues for the computer to deal with.

Why 24? Supposedly, it more closely mimics human sight when you are turning your head while watching things. It gets a particular type of 'softness' to the image. Especially when the shutter is "180 degrees" ... meaning, half the time of the framerate.

So for 24fps shooting, the shutter is 'best' at 1/48th of a second. For 50fps, it would be 1/25th of a second. Many cameras can be set for video shooting to do the "degree" type thing, so you would use 180 for normal shooting.

But you are the master of your work, and it doesn't look like you must comply with delivery specs ... you can do what you want. So ... try the "standard" way, and other things, and see what you like.

[vidar_8659]

Nice! Selv holder jeg til utenfor Stavanger 🙂

So to conclude, there is no problem with having multiple fps videos in the same sequence. And I create the project in the same fps i want in the finished video? 🙂

[R Neil Haugen]

Mostly akkuarat ... mostly?

Yea, typically you just add the media to the sequence. Although one thing to be aware of, is Premiere will match the clip properties of a clip used in "create sequence from selected clip", dragging a clip to a blank timeline panel, or onto the "new item" icon in the project panel.

So that needs to be in your export settings for framerate/size ... so it doesn't hurt to save a preset of your normal export needs, and do a "new sequence" from the menu, choosing your preset.

Most of the time, dropping a non-matched clip for framerate gets applied usably. It will even at times look at say 4x framerate media and play that at every frame as a normal frame speed ... so it's 4x slo-mo.

If you don't want it to be slo-mo, you would select the clip, right-click Speed/Duration, and set it for the appropriate time difference. Which you kinda need to calculate. But if you have 4x slo-mo, meaning at four times the framerate of the sequence, you'd type in 25%, right?

Then Premiere will dump (skip) frames to make it faster. It's more 'smooth' if you are working in straight mulitples of course, as if it needs to dump irregularly, it will probably need to 'create' frames via interpolation. Which isn't normally as good as 'original' frames. But at times, very needed and entirely adequate.