VoltsPerOctave.h

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#ifndef __VoltsPerOctave_hpp__
#define __VoltsPerOctave_hpp__
 
#include "FloatArray.h"
#include "basicmaths.h"
 
/*
 * Converts samples into volts and frequencies, following 1V/octave tuning.
 * Tuned to 440Hz. Change base note with setTune(float octave).
 */
class VoltsPerOctave {
private:
  float tune;
public:
  float offset;
  float multiplier;
  VoltsPerOctave(bool input = true);
  VoltsPerOctave(float offset, float multiplier);
  // Tune the frequency converter to octaves up or down.
  // For semitones divide by 12. For cents divide by 1200.
  void setTune(float octaves){
    tune = octaves;
  }
  void setMidiNote(float note){
    tune = (note-69)/12.0f; // 440Hz == A4 == MIDI Note 69
  }
  float getFrequency(float sample){
    return voltsToHertz(sampleToVolts(sample) + tune);
  }
  float getSample(float frequency){
    return voltsToSample(hertzToVolts(frequency) + tune);
  }
  float sampleToVolts(float sample){
    return (sample-offset) * multiplier;
  }
  static float voltsToHertz(float volts){
    return 440.f * exp2f(volts);
  }
  static float hertzToNote(float freq){
    return 12 * log2f(freq/440.f) + 69;
  }
  static float noteToHertz(float note){
    return 440.0f * exp2f((note - 69) / 12);
  }
  float voltsToSample(float volts){
    return volts / multiplier + offset;
  }
  static float hertzToVolts(float hertz){
    return log2f(hertz/440.0f);
  }
  void getFrequency(FloatArray samples, FloatArray output);
  void getFrequency(FloatArray samples);
  void getSample(FloatArray frequencies, FloatArray output);
  void getSample(FloatArray frequencies);
};
 
#endif /* __VoltsPerOctave_hpp__ */