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Diffstat (limited to 'libs/qm-dsp/base/Pitch.cpp')
-rw-r--r-- | libs/qm-dsp/base/Pitch.cpp | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/libs/qm-dsp/base/Pitch.cpp b/libs/qm-dsp/base/Pitch.cpp new file mode 100644 index 0000000000..9ba8b4b3f7 --- /dev/null +++ b/libs/qm-dsp/base/Pitch.cpp @@ -0,0 +1,46 @@ +/* -*- 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; +} + |