Syncing two clips with different frame rates

[nMcC503]

Hey folks, 

I'm editing footage of a shooter shooting a clay target. I can't get two clips to sync up, and I suspect it has something to do with the different frame rates. 

One clip is shot over the shooter's shoulder. It was shot on an iPhone 11 and has a frame rate of 29.97.

The other clip comes from a ShotKam, which is a camera installed on the barrel of the shotgun. It has a frame rate of 33.33. I was told that the footage is shot at 100 fps and plays back at 33 and 1/3rd fps. This clip is in a smaller frame in the corner of the video. The ShotKam footage captures 1.5 seconds in front of the shot and 1.5 seconds after the shot. 

To me, it seemed logical to just sync up the "bang" audio of the gun from both clips as a starting point, and then tweak it from there. But because of the discrepancies in the frame rates, I can't seem to get them to sync up. Or perhaps there’s something else I’m missing

Bottom line: I want the red dot on the ShotKam clip to start moving at the exact second (or frame) that the barrel of the gun starts moving in the iPhone clip, and then move in sync with the gun barrel moving. 

My conundrum, in other words, is what do I have to do to the iPhone clip to make it sync with the ShotKam clip (or vice versa)?

I've tried speeding up the ShotKam clip by 1/3 to match the speed of the iPhone clip, and tried slowing down the iPhone clip by 1/3 to match the Shotkam clip. No dice on either.

I understand that changing the speed/duration is different from changing frame rate, and I know how to change the frame rate of the clips/timeline. I just can't figure out how to make them sync!

I reached out to a professional and here was his response:

"So I've tried getting this right. I adjusted the 33 fps to 29.97 but it just doesn't want to align when you say pull. I can get the shot and clay disc breaking but the small screen seems like the disc shows in the screen before you say pull. I don't know that I can figure it out to align perfectly when you say pull without making it look like a jumpcut."

Searching around this forum, it looks like some people have suggested HandBrake to convert the frame rates, but I'm not sure which video I should change, and what I should do to it!

Truly appreciate any help you can offer. 

[Ann Bens]

Convert 33 frames with Handbrake make sure its constant framerate.

[nMcC503]

You mean convert the 29.97 FPS clip to 33.33? Or change them both to 33 FPS? Or something else?

[R Neil Haugen]

She meant set the 33fps media to 29.97 by converting it in Handbrake. Then import that file into Premiere.

Neil

[Michael Grenadier]

your iphone footage is probably variable frame rate and your other footage may also be vfr.   First thing is to convert to a constant frame rate.  The behavior of vfr material is unpredictable and may be where the problem lies.
use mediainfo to determine whether your source is variable or constant frame rate

https://mediaarea.net/en/MediaInfo/Download

if it's variable use handbrake to convert to constant frame rate

https://handbrake.fr
and here's a tutorial on how to use handbrake

https://www.youtube.com/watch?time_continue=34&v=xlvxgVREX-Y

then you can put markers at the places you want to synch up on both clips and adjust the speed til they markers line up...  

[nMcC503]

Thanks much.

They both have variable frame rates. Should I convert them both to a constant frame rate? I'm guessing I should convert them both to 29.97, since 33 and 1/3 isn't an option to pick. 

[Ann Bens]

Yes convert both as you will run into issues especially when using the audio.