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/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
/*
QM DSP library
Centre for Digital Music, Queen Mary, University of London.
This file Copyright 2006 Chris Cannam.
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version. See the file
COPYING included with this distribution for more information.
*/
#include "Pitch.h"
#include <math.h>
float
Pitch::getFrequencyForPitch(int midiPitch,
float centsOffset,
float concertA)
{
float p = float(midiPitch) + (centsOffset / 100);
return concertA * powf(2.0, (p - 69.0) / 12.0);
}
int
Pitch::getPitchForFrequency(float frequency,
float *centsOffsetReturn,
float concertA)
{
float p = 12.0 * (log(frequency / (concertA / 2.0)) / log(2.0)) + 57.0;
int midiPitch = int(p + 0.00001);
float centsOffset = (p - midiPitch) * 100.0;
if (centsOffset >= 50.0) {
midiPitch = midiPitch + 1;
centsOffset = -(100.0 - centsOffset);
}
if (centsOffsetReturn) *centsOffsetReturn = centsOffset;
return midiPitch;
}
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