Playback speed question

Report · Oct 21, 2019

I was recently testing out the slo-mo video features of a new Nikon Z7 camera by recording a 5 second MP4 at 120 FPS. I then imported it into Premiere Pro CC and in Speed/Duration I set it to 25%. On the timeline it changed to 20 seconds, just as you would expect. The resulting video, when exported, looks like the 4X slow-mo that it is, and looks pretty good, too - I like this camera . . .

BUT here's my question. In the Export dialog it correctly identifies the source as 120 (119.88) fps. But it lists the Output as 60 fps. Why isn't it 30fps? It plays like it's at 30, i.e., it's 4 times slower than the original, not just half. I tried both Frame Sampling and Frame Blending options in the Speed Duration dialog with the same result.

Thanks in advance!

Report · Oct 22, 2019

Did you notice your source sequence is listed at the original framerate of the clip?

I think perhaps you dragged the clip to a blank timeline, then set the speed/duration option?

Try changing the clip in the bin ... then drag that onto a blank timeline to create a new sequence. Does the sequence now show a 30fps framerate?

Then export from that sequence and see what you get.

Neil

Report · Oct 22, 2019

Did you notice your source sequence is listed at the original framerate of the clip?

Yes, I said that in my original question ... "In the Export dialog it correctly identifies the source as 120 (119.88) fps."

My question isn't what did I do to get it that way, it's what way did it get, i.e., what did Premiere Pro do? A 5 second 120 fps source has been turned into a 20 second 1/4 speed slow motion video. But Premiere Pro says the output is 60 fps. That implies that additional frames have been added at a 2:1 ratio. In other words, the original had roughly 600 frames in it (5 seconds times 120 fps) and the new one has 1200 frames in it (20 seconds times 60 fps). Does Premiere Pro add interpolated frames when you set speed/duration? Why doesn't it just make 600 frames at 30 fps?

PS - I tried your suggestion of setting Speed/Duration in the bin before dragging it to the timeline and got exactly the same result.

Report · Oct 31, 2019

"Why isn't it 30fps?"

Because the Framerate under "Basic Video Settings" in the export dialogue is not not set to "Match source" neither to "30 fps" it is instead set to "60fps".

Set it to 30 so that no frames will be added. By setting it to 60, it is normal that frames will be duplicated.