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 Post subject: Calculating length based on bpm?
PostPosted: Mon May 30, 2011 10:54 pm 
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Weird question....how would I go about figuring out the length (in seconds) of say, 4 bars of a 80bpm track, or 1 bar of a 100bpm track...or whatever, is there any way to calculate this? I'm not a technically minded person and I know nothing about music theory at all, let alone the maths of it all. I know how to operate my two samplers, I know whether something sounds dope or not to my ears, and up until now that's all I thought I needed to know, guess I was wrong. I've searched the internet on and off pretty much all evening but I'm just getting more confused every time I come up with some information.

Can anyone help? Thanks


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 Post subject: Re: Calculating length based on bpm?
PostPosted: Tue May 31, 2011 1:12 am 
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bpm is beats per minute .
i dont know the formula exactly, but it would be easy enough with some basic math skills ( which i dont have :lol: )

60 bpm 2 bars is 8 seconds.
1.5 second difference between 60 and 70
70 bpm 2 bars is 6.85 seconds
.85 second difference between 70 and 80
80 bpm 2 bars is 6 seconds
.67
90 bpm 2 bars is 5.33 seconds .


so looking at that is appears the time in seconds versus the bpm accelerates as it goes up, i know my math is really funny and it never gets me anywhere because i dont know algebra but maybe this can be a foundation for somewho does.

sorry for my hill billy education

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 Post subject: Re: Calculating length based on bpm?
PostPosted: Wed Jun 01, 2011 1:46 am 
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I think I figured out how to find the time difference between two.

Thanks a lot


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 Post subject: Re: Calculating length based on bpm?
PostPosted: Thu Jun 02, 2011 8:00 am 
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i think its interesting, because to pitch a sample an octave makes it play twice as fast. which is cool for bass sometimes, make a copy of the sample and pitch it down an octave. and play it with the original and filter it, its dope. up is cool to for speeding up drums double.

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 Post subject: Re: Calculating length based on bpm?
PostPosted: Thu Jun 02, 2011 11:21 am 
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the formula is the following: 60 / bpm = one bar in seconds.

there's also a transposition formula: {sample length} * (n / 120)^2
where 'n' is transposition units in cents, logarithmic units of pitch. one half-tone equals 10 cents. so if you want to transpose your sample one half-tone up, the formula is {sample length} * (10/120)^2; if you want to make it one tone lower, it's {sample length} * (-20/120)^2. i don't know if '^2' is a common way of writing square root.

hope this helps.

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 Post subject: Re: Calculating length based on bpm?
PostPosted: Mon Jun 06, 2011 6:11 am 
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shit yall got it to a science. lol

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 Post subject: Re: Calculating length based on bpm?
PostPosted: Mon Jun 06, 2011 9:11 am 
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60 divided by BPM = how many seconds 1 beat takes.

so say

75BPM

60 divided by 75 = 0.8

so 1 beat at 75BPM is 0.8seconds.

for 1 bar just multiply 4 by 0.8 or whatever the result of the first equation is... for more than 1 bar.. well pretty obvious

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 Post subject: Re: Calculating length based on bpm?
PostPosted: Tue Jun 07, 2011 12:07 am 
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so if 1 beat at 60 bpm is .8 seconds ,

then 2 bars is just double ? same for 120 bmp just divide by 2 ?

does anyone know if it works like this for pitching samples ? because a sample plays exactly double when it is pitched 1 octave up . so the length of the sample ends up exactly half

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 Post subject: Re: Calculating length based on bpm?
PostPosted: Tue Jun 07, 2011 1:09 am 
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Tempo and Pitch-Shifting Calculator:
http://www.thewhippinpost.co.uk/tools/t ... ulator.htm
midway down
:idea: :idea:

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 Post subject: Re: Calculating length based on bpm?
PostPosted: Tue Jun 07, 2011 2:21 am 
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Yo thanks to everyone who has posted in this thread. Big help.

dope resource, kel, bookmarked.
cartesia wrote:
60 divided by BPM = how many seconds 1 beat takes.

so say

75BPM

60 divided by 75 = 0.8

so 1 beat at 75BPM is 0.8seconds.

for 1 bar just multiply 4 by 0.8 or whatever the result of the first equation is... for more than 1 bar.. well pretty obvious

Ok I think I've definitely got it down now. So I divide 60 by the bpm to find the length of one beat, then multiply that figure by 4....so one bar at 75bmp would be 3.2 seconds. Would that be right?

This is something I've literally lost sleep over so once again thank you all.


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 Post subject: Re: Calculating length based on bpm?
PostPosted: Tue Jun 07, 2011 3:32 am 
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1 beat @ 75BPM = 0.8seconds

so...

4 beats @ 75BPM = 0.8 times 4

= 3.2seconds

yep, you got it!

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