# Formula for sound speed when overcranking/undercranking

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### #1 Kip Kubin

Kip Kubin
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Posted 25 July 2007 - 08:02 PM

Please help me out. I'm lousy with math and know this formula must be out there somewhere but I couldn't find it.

How do I calculate the amount to increase or decrease the tempo of a song to overcrank/undercrank and still have the lip sync match.

fron 24 fps to 32/40 or 18

Kip
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### #2 e gustavo petersen

e gustavo petersen
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Posted 25 July 2007 - 08:48 PM

For a 24 fps base:

24 / n
n = frames per second you want to shoot

So if you want to shoot at 32fps = 24/32 = .75 or 75% -> so you'll want to reduce the length (speed up) of your music to 75% is real time length. So if you have a 4 minute song (240 seconds), you'll want to reduce (or speed up) the song to 3 minutes (or 180 seconds). 240x.75=180
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### #3 Kip Kubin

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Posted 25 July 2007 - 10:20 PM

For a 24 fps base:

24 / n
n = frames per second you want to shoot

So if you want to shoot at 32fps = 24/32 = .75 or 75% -> so you'll want to reduce the length (speed up) of your music to 75% is real time length. So if you have a 4 minute song (240 seconds), you'll want to reduce (or speed up) the song to 3 minutes (or 180 seconds). 240x.75=180

Thank you
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