158 lines
3.7 KiB
C++
158 lines
3.7 KiB
C++
/**********************************************************************
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Audacity: A Digital Audio Editor
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Audacity(R) is copyright (c) 1999-2012 Audacity Team.
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License: GPL v2. See License.txt.
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PitchName.cpp
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Vaughan Johnson and Dominic Mazzoni.
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******************************************************************//**
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\file PitchName.cpp
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\brief Utilities for converting from frequency to pitch
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and from pitch to absolute (e.g., C4 for middle C)
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or nominal (A through G#) pitch name.
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*//*******************************************************************/
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#include <math.h>
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#include <stdio.h>
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#include "PitchName.h"
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double FreqToMIDInote(const double freq)
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{
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// Make the calculation relative to A440 (A4), note number 69.
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return (69.0 + (12.0 * (log(freq / 440.0) / log(2.0))));
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}
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double MIDInoteToFreq(const double dMIDInote)
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{
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return (440.0 * pow(2.0, (dMIDInote - 69.0) / 12.0));
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}
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unsigned int PitchIndex(const double dMIDInote)
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{
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// MIDI numbers can be negative. Round in the right direction.
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double dRound = (dMIDInote < 0.0) ? -0.5 : 0.5;
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int nPitchIndex = ((int)(dMIDInote + dRound) % 12);
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// Because of the modulo, we know we're within 12 of positive, if dMIDInote is negative.
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if (nPitchIndex < 0)
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nPitchIndex += 12;
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return nPitchIndex;
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}
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int PitchOctave(const double dMIDInote)
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{
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double dRound = (dMIDInote < 0.0) ? -0.5 : 0.5;
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return ((int)((dMIDInote + dRound) / 12.0) - 1);
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}
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static wxChar gPitchName[10];
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static wxChar * pPitchName;
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wxChar * PitchName(const double dMIDInote, const bool bWantFlats /* = false */)
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{
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pPitchName = gPitchName;
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switch (PitchIndex(dMIDInote)) {
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case 0:
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*pPitchName++ = wxT('C');
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break;
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case 1:
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if (bWantFlats) {
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*pPitchName++ = wxT('D');
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*pPitchName++ = wxT('b');
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} else {
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*pPitchName++ = wxT('C');
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*pPitchName++ = wxT('#');
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}
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break;
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case 2:
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*pPitchName++ = wxT('D');
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break;
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case 3:
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if (bWantFlats) {
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*pPitchName++ = wxT('E');
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*pPitchName++ = wxT('b');
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} else {
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*pPitchName++ = wxT('D');
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*pPitchName++ = wxT('#');
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}
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break;
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case 4:
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*pPitchName++ = wxT('E');
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break;
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case 5:
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*pPitchName++ = wxT('F');
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break;
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case 6:
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if (bWantFlats) {
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*pPitchName++ = wxT('G');
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*pPitchName++ = wxT('b');
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} else {
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*pPitchName++ = wxT('F');
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*pPitchName++ = wxT('#');
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}
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break;
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case 7:
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*pPitchName++ = wxT('G');
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break;
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case 8:
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if (bWantFlats) {
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*pPitchName++ = wxT('A');
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*pPitchName++ = wxT('b');
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} else {
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*pPitchName++ = wxT('G');
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*pPitchName++ = wxT('#');
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}
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break;
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case 9:
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*pPitchName++ = wxT('A');
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break;
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case 10:
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if (bWantFlats) {
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*pPitchName++ = wxT('B');
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*pPitchName++ = wxT('b');
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} else {
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*pPitchName++ = wxT('A');
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*pPitchName++ = wxT('#');
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}
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break;
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case 11:
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*pPitchName++ = wxT('B');
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break;
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}
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*pPitchName = wxT('\0');
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return gPitchName;
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}
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wxChar * PitchName_Absolute(const double dMIDInote, const bool bWantFlats /* = false */)
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{
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PitchName(dMIDInote, bWantFlats);
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// PitchName sets pPitchName to the next available char in gPitchName,
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// so it's ready to append the register number.
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wxSnprintf(pPitchName, 8, wxT("%d"), PitchOctave(dMIDInote));
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return gPitchName;
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}
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double PitchToMIDInote(const unsigned int nPitchIndex, const int nPitchOctave)
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{
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return ((double)nPitchIndex + (((double)nPitchOctave + 1.0) * 12.0));
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}
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double PitchToFreq(const unsigned int nPitchIndex, const int nPitchOctave)
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{
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return MIDInoteToFreq(PitchToMIDInote(nPitchIndex, nPitchOctave));
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}
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