var amp;

var button;

​

var volhistory = [];

​

function toggleSong() {

  if (song.isPlaying()) {

    song.pause();

  } else {

    song.play();

  }

}

​

function preload() {

  song = loadSound('Mysong.mp3');

}

​

function setup() {

  createCanvas(200, 200);

  button = createButton('toggle');

  button.mousePressed(toggleSong);

  song.play();

  amp = new p5.Amplitude();

}

​

function draw() {

  background(0);

  var vol = amp.getLevel();

  volhistory.push(vol);

  stroke(255);

  noFill();

  push();

  var currentY = map(vol, 0, 1, height, 0);

  translate(0, height / 2 - currentY);

  beginShape();

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

    var y = map(volhistory[i], 0, 1, height, 0);

    vertex(i, y);

  }

  endShape();

  pop();

  if (volhistory.length > width - 50) {

    volhistory.splice(0, 1);

  }

​

  stroke(255, 0, 0);

  line(volhistory.length, 0, volhistory.length, height);

}