Maths of Slo Mo at DVinfo.net

Ewan Macleod · June 6th, 2007, 10:48 PM

Hi all, Im working on a 16mm music video and planning to shoot at a frame rate of 33.3fps to acheive a slight surreal edge

Im wondering how to calculate exactly how much the song needs to be sped up so the band can give a synced performance as we shoot.

Cheers, ewan.

Bob Hart · June 7th, 2007, 01:00 AM

24 (or 25) FPS---------------100
____________ X ______________

33.5 FPS--------------------1

Ignore the dashed lined between the numbers. Spacing won't display the numbers correctly.

Formula for expressing percentage shortening of soundtrack playback time I think??? but please check with somebody else - don't take my word for it as I failed maths from Year 5 onwards.

Is your camera motor still xtal sync at the higher frame rate?

Odd Nydren · June 7th, 2007, 07:50 AM

How about this:

Ok video is 25fps...that should make 33.3fps about 33.2% faster than 25fps.
(33.3 / 25 = 1.32 -> 33.2%)

..that means if its done right, the resulting song length should be:
song_in_seconds * 0.668 = 33.32% faster song in seconds
(1 - 0.332 = 0.668)

..but don't quote me on that ;)
If I where you I would just do a quick test!

cheers

//O.

June 6th, 2007, 10:48 PM	#1
Ewan Macleod Tourist Join Date: Mar 2007 Location: Melbourne Posts: 1	Maths of Slo Mo Hi all, Im working on a 16mm music video and planning to shoot at a frame rate of 33.3fps to acheive a slight surreal edge Im wondering how to calculate exactly how much the song needs to be sped up so the band can give a synced performance as we shoot. Cheers, ewan.

June 7th, 2007, 01:00 AM	#2
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,477	24 (or 25) FPS---------------100 ____________ X ______________ 33.5 FPS--------------------1 Ignore the dashed lined between the numbers. Spacing won't display the numbers correctly. Formula for expressing percentage shortening of soundtrack playback time I think??? but please check with somebody else - don't take my word for it as I failed maths from Year 5 onwards. Is your camera motor still xtal sync at the higher frame rate? Last edited by Bob Hart; June 7th, 2007 at 01:05 AM. Reason: error

June 7th, 2007, 07:50 AM	#3
Odd Nydren Regular Crew Join Date: Jan 2007 Location: London, UK Posts: 88	How about this: Ok video is 25fps...that should make 33.3fps about 33.2% faster than 25fps. (33.3 / 25 = 1.32 -> 33.2%) ..that means if its done right, the resulting song length should be: song_in_seconds * 0.668 = 33.32% faster song in seconds (1 - 0.332 = 0.668) ..but don't quote me on that ;) If I where you I would just do a quick test! cheers //O.