Difference between 30 fps and 60 fps does not make sense?

[XilburQost]

I am creating 60 fps animations via a 3D app (Blender) with the output as single PNG files, one file per frame. These import fine into Premiere Pro. My Premiere Pro default fps is set to 30, so once imported I go to Sequence > Sequence Settings... > Timebase and change it from 30 to 60 frames/second. What's weird is that when I export the animations at both 30 and 60 fps, both run for the same total amount of time; shouldn't 60 fps = an animation twice as fast and half as long?

Another thing I have noticed is that I have a short animation consisting of 2400 single images, and when I import them into Premiere Pro at the default setting of 30 fps, the total frame count is 2400, however, when I change the Sequence setting to 60 fps, the frame count doubles to 4800; why? The source is still 2400 single images. Something about the fps settings I am not understanding; can anyone help? Thanks. Premiere Pro 2.22, Windows 11

[Jeff Bugbee]

Remember, 10 seconds of 30fps and 10 seconds of 60fps both run for exactly 10 seconds. 60fps simply has twice the number of frames. Framerate does not determine video length.

Your frame count is doubling because Premiere has to create (duplicate) frames in order to match your selected frame rate.

[XilburQost]

Jeff Bugbee, thank you for the response. I get that's what's happening, but simply doubling frames seems to me to be a pseudo 60 fps; what if I want every frame at 60 fps to be unique, i.e., 2400 frames rather than 4800 frames?

[Jeff Bugbee]

Premiere has something called "Optical Flow." Instead of duplicating frames, it attempts to blend 2 different frames into an "in between" unique frame. Sometimes this looks okay, sometimes not. Really depends on the footage. But if you give Premiere 30 unique frames but want 60 unique frames, ideally you would supply Premiere with 60 unique frames. Those extra frames gotta come from somewhere.

[thepixelsmith]

I guess the question is what are you trying to achieve?

If you play high frame rate video back at it's native frame rate it looks normal.

But if you were to play high frame rate footage back at a lower frame rate it would look slower.

[XilburQost]

thepixelsmith, currently I'm an animation and video production noob. 🙂 As I delve into creating animations I am exploring video output settings to see what nets the best possible results for different kinds of subject matter. At this point, I would like to see what 60 fps with a unique image per frame looks like; I don't care how fast or slow it runs. Is there a quick way to achieve this in Premiere Pro? Thanks.

[Averdahl · Accepted solution]

I am creating 60 fps animations via a 3D app (Blender) with the output as single PNG files, one file per frame. These import fine into Premiere Pro. My Premiere Pro default fps is set to 30

By @XilburQost

To fix this, go to Edit > Preferences > Media and change the Indeterminate Media Timebase to 60 and click OK. From now on all image sequenceses you import will come in as 60 fps instead of 30 fps.

This will do the trick and you won´t have to change/mess with the timebase of the sequence. Important to know is that all image sequences you have imported won´t change but all image sequences you import from now will come in as 60 fps. 

[nickn35634941]

I just had the exact same issue, in the export settings I said the rate is 60 but it ignored this and rendered to 30 anyway. seems really weird to me but your answer fixed my issue