* @name Mic Threshold

 * @description <p>Trigger an event (draw a rectangle) when the Audio Input

 * volume surpasses a threshold.</p>

 * <p><em><span class="small"> To run this example locally, you will need the

 * <a href="http://p5js.org/reference/#/libraries/p5.sound">p5.sound library</a>

 * and a running <a href="https://github.com/processing/p5.js/wiki/Local-server">local server</a>.</span></em></p>

 */

// Adapted from Learning Processing, Daniel Shiffman

// learningprocessing.com

var input;

var analyzer;

​

function setup() {

  createCanvas(710, 200);

  background(255);

​

  // Create an Audio input

  input = new p5.AudioIn();

​

  input.start();

}

​

function draw() {

  // Get the overall volume (between 0 and 1.0)

  var volume = input.getLevel();

​

  // If the volume > 0.1,  a rect is drawn at a random location.

  // The louder the volume, the larger the rectangle.

  var threshold = 0.1;

  if (volume > threshold) {

    stroke(0);

    fill(0, 100);

    rect(random(40, width), random(height), volume*50, volume*50);

  }

​

  // Graph the overall potential volume, w/ a line at the threshold

  var y = map(volume, 0, 1, height, 0);

  var ythreshold = map(threshold, 0, 1, height, 0);

​

  noStroke();

  fill(175);

  rect(0, 0, 20, height);

  // Then draw a rectangle on the graph, sized according to volume

  fill(0);

  rect(0, y, 20, y);

  stroke(0);

  line(0, ythreshold, 19, ythreshold);

}

​