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