# Click track prep for music video

I'm working on a project for a music video where we're attempting to record video with a sped up version of the song, and then slowing down the video to match the original recording.

anybody have any experience with this? i'm looking for insight on how much to adjust the speed of the edited song to match up with the change in frame rate or time code.

take a look at weezer's 'undone' video for an example.

• What is the frame rate of the finished video? What frame rate is the high speed footage being shot at?
– user49
Apr 5, 2012 at 21:47
• ends up i missed out on the job anyway. bummer.
– Jef
Apr 9, 2012 at 21:22
• Now you have time to make your own :P Apr 10, 2012 at 16:29

If you are going to be slowing down the video by 2x, you speed up the click track/music by 2x.

So let's say the video is shot at 60 fps, then it's slowed down to 30 fps. Since the final framerate is 30fps, that's also what the music will be synced to at normal speed. Let's say the music is 120 bpm normally. It's rate has a 1:1 relationship with the music video's final framerate, in this case a clean 30 fps. So if you are shooting at 60 fps: 30/60 = 0.5

That's the ratio, so to get the bpm you want to use when shooting, just divide your starting bpm (120) by the ratio. 120/ 0.5 = 240

If your final framerate is 29.97, but you are shooting at 60 fps: 29.97 / 60 = .4995 So with a 120 bpm track: 120 / .4995 = 240.24024

It's a linear relationship. You just need to know A) The original framerate B) The final framerate C) The original bpm

[new bpm] / [old bpm] = [original framerate] / [final framerate]

Solve for [new bpm]

a / b = c / d

a = bc / d

• And then, cross-multiplication!!!
– MtL
Apr 6, 2012 at 20:13
• Yup. @Jef: en.wikipedia.org/wiki/Cross-multiplication so you have an equation [new bpm] / [old bpm] = [original framerate] / [final framerate]. Solve for [new bpm]. a / b = c / d : a = bc / d Apr 6, 2012 at 20:53
• FANTASTIC!!! this is exactly what i was looking for. Math was eluding my brain. Thank you muchos. so simple!
– Jef
Apr 9, 2012 at 17:10

I haven't personally had any experience with this but it sounds like something one of my lecturers from the easy rollers talked about what they did in the film Lock Stock & Two Smoking Barrels. check it out on youtube and contact them they might be able to help!

We just did this for my bands music video - we filmed at 50fps and slowed it down to 30fps. it might be worth considering how tricky the song will be to play at 1.6 or 2 times the speed- we were rather struggling at 1.6! The end results are really great though, gives a very serene glossy look to everything :-)