var carrier; // this is the oscillator we will hear

var modulator; // this oscillator will modulate the frequency of the carrier

​

var analyzer; // we'll use this visualize the waveform

​

// the carrier frequency pre-modulation

var carrierBaseFreq = 220;

​

// min/max ranges for modulator

var modMaxFreq = 112;

var modMinFreq = 0;

var modMaxDepth = 150;

var modMinDepth = -150;

​

​

var song;

​

function preload() {

  song = loadSound('https://s3.amazonaws.com/findthe/cow.mp3');

}

​

​

function setup() {

  var cnv = createCanvas(800,400);

  noFill();

  song.loop();

  //song.disconnect();

  carrier = new p5.Oscillator('sine');

  carrier.amp(0); // set amplitude

  carrier.freq(carrierBaseFreq); // set frequency

  //carrier.start(); // start oscillating

​

  // try changing the type to 'square', 'sine' or 'triangle'

  modulator = new p5.Oscillator('sawtooth');

  modulator.start();

​

  // add the modulator's output to modulate the carrier's frequency

  modulator.disconnect();

  //carrier.freq( modulator );

  modulator.connect(song);

  //song.connect(modulator);

​

  // create an FFT to analyze the audio

  analyzer = new p5.FFT();

​

  // fade carrier in/out on mouseover / touch start

  toggleAudio(cnv);

}

​

function draw() {

  background(30);

​

  // map mouseY to modulator freq between a maximum and minimum frequency

  var modFreq = map(mouseY, height, 0, modMinFreq, modMaxFreq);

  modulator.freq(modFreq);

​

  // change the amplitude of the modulator

  // negative amp reverses the sawtooth waveform, and sounds percussive

  //

  var modDepth = map(mouseX, 0, width, modMinDepth, modMaxDepth);

  modulator.amp(modDepth);

​

  // analyze the waveform

  waveform = analyzer.waveform();

​

  // draw the shape of the waveform

  stroke(255);

  strokeWeight(10);

  beginShape();

  for (var i = 0; i < waveform.length; i++){

    var x = map(i, 0, waveform.length, 0, width);

    var y = map(waveform[i], -1, 1, -height/2, height/2);

    vertex(x, y + height/2);

  }

  endShape();

​

  strokeWeight(1);

  // add a note about what's happening

  text('Modulator Frequency: ' + modFreq.toFixed(3) + ' Hz', 20, 20);

  text('Modulator Amplitude (Modulation Depth): ' + modDepth.toFixed(3), 20, 40);

  text('Carrier Frequency (pre-modulation): ' + carrierBaseFreq + ' Hz', width/2, 20);

​

}

​

// helper function to toggle sound

function toggleAudio(cnv) {

  cnv.mouseOver(function() {

    song.amp(1.0, 0.01);

  });

  cnv.touchStarted(function() {

    song.amp(1.0, 0.01);

  });

  cnv.mouseOut(function() {

    song.amp(0.0, 1.0);

  });

}

​