audacity/src/PitchName.cpp

/**********************************************************************

   Audacity: A Digital Audio Editor
   Audacity(R) is copyright (c) 1999-2012 Audacity Team.
   License: GPL v2.  See License.txt.

  PitchName.cpp
  Vaughan Johnson and Dominic Mazzoni.

******************************************************************//**

\file PitchName.cpp
\brief   Utilities for converting from frequency to pitch
  and from pitch to absolute (e.g., C4 for middle C)
  or nominal (A through G#) pitch name.

*//*******************************************************************/


#include "Audacity.h"
#include "PitchName.h"

#include <math.h>
#include <stdio.h>

#include "Internat.h"


double FreqToMIDInote(const double freq)
{
   // Make the calculation relative to A440 (A4), note number 69.
   return (69.0 + (12.0 * (log(freq / 440.0) / log(2.0))));
}

double MIDInoteToFreq(const double dMIDInote)
{
   return (440.0 * pow(2.0, (dMIDInote - 69.0) / 12.0));
}

unsigned int PitchIndex(const double dMIDInote)
{
   // MIDI numbers can be negative. Round in the right direction.
   double dRound = (dMIDInote < 0.0) ? -0.5 : 0.5;
   int nPitchIndex = ((int)(dMIDInote + dRound) % 12);

   // Because of the modulo, we know we're within 12 of positive, if dMIDInote is negative.
   if (nPitchIndex < 0)
      nPitchIndex += 12;

   return nPitchIndex;
}

int PitchOctave(const double dMIDInote)
{
   double dRound = (dMIDInote < 0.0) ? -0.5 : 0.5;
   return ((int)((dMIDInote + dRound) / 12.0) - 1);
}


TranslatableString PitchName(const double dMIDInote, const PitchNameChoice choice)
{
   static const TranslatableString sharpnames[12] = {
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("C"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("C\u266f"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("D"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("D\u266f"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("E"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("F"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("F\u266f"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("G"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("G\u266f"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("A"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("A\u266f"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("B"),
   };

   static const TranslatableString flatnames[12] = {
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("C"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("D\u266d"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("D"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("E\u266d"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("E"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("F"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("G\u266d"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("G"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("A\u266d"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("A"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("B\u266d"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("B"),
   };

   static const TranslatableString bothnames[12] = {
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("C"),
     /* i18n-hint: Two, alternate names of a musical note in the 12-tone chromatic scale */
      XO("C\u266f/D\u266d"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("D"),
      /* i18n-hint: Two, alternate names of a musical note in the 12-tone chromatic scale */
      XO("D\u266f/E\u266d"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("E"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("F"),
      /* i18n-hint: Two, alternate names of a musical note in the 12-tone chromatic scale */
      XO("F\u266f/G\u266d"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("G"),
      /* i18n-hint: Two, alternate names of a musical note in the 12-tone chromatic scale */
      XO("G\u266f/A\u266d"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("A"),
      /* i18n-hint: Two, alternate names of a musical note in the 12-tone chromatic scale */
      XO("A\u266f/B\u266d"),
      /* i18n-hint: Name of a musical note in the 12-tone chromatic scale */
      XO("B"),
   };

   const TranslatableString *table = nullptr;
   switch ( choice ) {
      case PitchNameChoice::Sharps: table = sharpnames; break;
      case PitchNameChoice::Flats: table = flatnames; break;
      case PitchNameChoice::Both: table = bothnames; break;
      default: wxASSERT(false); break;
   }

   return table[PitchIndex(dMIDInote)];
}

TranslatableString PitchName_Absolute(const double dMIDInote, const PitchNameChoice choice)
{
   // The format string is not localized.  Should it be?
   return Verbatim( wxT("%s%d") )
      .Format( PitchName(dMIDInote, choice), PitchOctave(dMIDInote) );
}

double PitchToMIDInote(const unsigned int nPitchIndex, const int nPitchOctave)
{
   return ((double)nPitchIndex + (((double)nPitchOctave + 1.0) * 12.0));
}

double PitchToFreq(const unsigned int nPitchIndex, const int nPitchOctave)
{
   return MIDInoteToFreq(PitchToMIDInote(nPitchIndex, nPitchOctave));
}