Changing frame rate to song for a music video shoot?

Ah lads, did ye not go to school? I've always found basic arithmetic skills pretty useful as an editor.

MODIFIED FRAME RATE divided by ORIGINAL FRAME RATE multiplied by 100 = desired percentage

e.g. 18 / 24 = 0.75 x 100 = 75% and so on.

QED 🙂

I don't know the first thing about TC generators, but I think I know what your numbers mean.

Your music track is just over 2 mins 54 secs.

At 24fps, the "bit" over 2 mins 54 secs is an additional 19 frames.

When you calibrate the TCG to 60 fps, there are now more frames for every second of music, so the number attached to that extra "bit" duration changes accordingly. (I'd have calculated it at 2:54:48, but like I say, I don't know anything about TCGs - could it be a drop frame issue associated with 23.98fps numbers?).

You could use FCP or Soundtrack Pro to speed up or slow the track. You'd have to do the maths yourself though - 75% for 18fps, 150% for 36, 200% for 48, 250% for 60, etc.

(On second thoughts, you won't have to do the maths, I've done it for you.)

Only kidding about the school remark, it's an Irish expression, no offense intended.

I was referring to the duration, not the speed, but I can see I didn't make this clear. (I think of it this way because I'm thinking of Soundtrack Pro's Time Stretch tool.)

If you shoot at 18fps for playback at 24, the music track should be sped up so that its new duration is 75% of its original duration. So in fact if you're looking at the inverse of those numbers for the amount to speed it up.

18 - 133.333%
36 - 66.666%
48 - 50%
60 - 40%

Hope that's better! Best of luck with it.




I should go back to school myself and learn how to make myself more clear. 🙂

Message was edited by: Denis Murphy

Well, are you shooting at 24fps or 23.976fps? I don't know much experience of 24fps workflows, but the way I understand it, it's normal to shoot at 24fps, and if a 23.976fps version is required, to conform to that rate later (i.e. after you're done editing). I could be wrong here.

Talk to your cameraperson and get some advice about the exact frame rate s/he's going to shoot at. If indeed it's 23.976 (which I doubt) then yes, you should use that number for "doing the math".

Rereading your post, it occurred to me that you might not be using an external TCG at all, is that correct? Are you planning to playback a quicktime movie on set with visual timecode reference and sync to that?

If so, I guess this would be the way to do it: Drop your audio into a 24fps sequence, allowing 10 secs or so of silence at beginning for cueing. Put a slug on the video track and add the Timecode filter to the slug. Export that timeline as a quicktime movie (audio and video), then import that back into FCP and apply the various speed changes required. Your visual TCG reference will be playing back at the same speed as the music.

If you use these files for sound playback on set and make sure you get a shot of the visual TC reference at every slate, it should work well for syncing later.

I'm only thinking off the top of my head here - I've never done this kind of shoot. I'm sure some other folks around here could chime in as this "varispeed" effect is done quite a lot in music videos.

Best of luck with it!