cannam@0: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
cannam@0: 
cannam@0: /*
cannam@0:     QM DSP library
cannam@0:     Centre for Digital Music, Queen Mary, University of London.
cannam@0:     This file Copyright 2006 Chris Cannam.
Chris@84: 
Chris@84:     This program is free software; you can redistribute it and/or
Chris@84:     modify it under the terms of the GNU General Public License as
Chris@84:     published by the Free Software Foundation; either version 2 of the
Chris@84:     License, or (at your option) any later version.  See the file
Chris@84:     COPYING included with this distribution for more information.
cannam@0: */
cannam@0: 
cannam@0: #include "Pitch.h"
cannam@0: 
cannam@79: #include <math.h>
cannam@0: 
cannam@0: float
cannam@0: Pitch::getFrequencyForPitch(int midiPitch,
cannam@0: 			    float centsOffset,
cannam@0: 			    float concertA)
cannam@0: {
cannam@0:     float p = float(midiPitch) + (centsOffset / 100);
cannam@0:     return concertA * powf(2.0, (p - 69.0) / 12.0);
cannam@0: }
cannam@0: 
cannam@0: int
cannam@0: Pitch::getPitchForFrequency(float frequency,
cannam@0: 			    float *centsOffsetReturn,
cannam@0: 			    float concertA)
cannam@0: {
cannam@0:     float p = 12.0 * (log(frequency / (concertA / 2.0)) / log(2.0)) + 57.0;
cannam@0: 
cannam@0:     int midiPitch = int(p + 0.00001);
cannam@0:     float centsOffset = (p - midiPitch) * 100.0;
cannam@0: 
cannam@0:     if (centsOffset >= 50.0) {
cannam@0: 	midiPitch = midiPitch + 1;
cannam@0: 	centsOffset = -(100.0 - centsOffset);
cannam@0:     }
cannam@0:     
cannam@0:     if (centsOffsetReturn) *centsOffsetReturn = centsOffset;
cannam@0:     return midiPitch;
cannam@0: }
cannam@0: