Subject: Re: [linux-audio-dev] math question re. tempo changes
From: Eli Brandt (eli_AT_v.gp.cs.cmu.edu)
Date: ti joulu 07 1999 - 17:10:17 EST
est_AT_hyperreal.org wrote:
[a good explanation of what I was trying to do]
> I get:
>
> b_t_c(beat)
> = Integral(from 0 to beat) start_tempo + k * b d(b)
> = start_tempo * beat + k * beat^2 / 2
If Paul says this one is doing the right thing for him, great, and
there was surely something troubling about finding a natural log in
mine. But I'm confused.
Say k is positive, so the tempo -- beats per second -- is increasing.
As we go along, each beat ought to map to less seconds. But that
beats_to_secs() formula has later beats mapping to /more/ seconds;
k is bringing in a superlinear term. This seems like a secs_to_beats().
(The difference we have is what we put in the
beats_to_secs = integral foo d(beat)
I figure tempocurve() is d(b)/d(s), so I took the reciprocal.)
> I haven't done this sort of thing in years..but what
> better place to refresh than in public. :D
Yeh, tell me about it.
--
Eli Brandt | eli+@cs.cmu.edu | http://www.cs.cmu.edu/~eli/
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