let previousPixels;

let sounds = [];

let currentFile;

let hue = 360;

let lastFrameKeyPressed = false;

​

function preload() {

  for (let i = 0; i < 5; i++) {

    let fileName = "sounds/" + i + ".mp3";

    sounds[i] = loadSound(fileName);

  }

}

​

function copyImage(src, dst) {

  let n = src.length;

  if (!dst || dst.length != n) dst = new src.constructor(n);

  while (n--) dst[n] = src[n];

  return dst;

}

​

function setup() {

  createCanvas(600, 600);

​

  currentFile = sounds[Math.floor(random(5))];

  colorMode(HSB, 360, 100, 100);

​

  capture = createCapture(VIDEO);

  capture.size(640, 360);

  capture.hide();

  pixelDensity(1);

  noStroke();

}

​

function draw() {

  capture.loadPixels();

  let total = 0;

  if (capture.pixels.length > 0) {

    // don't forget this!

    if (!previousPixels) {

      previousPixels = copyImage(capture.pixels, previousPixels);

    } else {

      let thresholdAmount = 100;

      thresholdAmount *= 3; // 3 for r, g, b

      for (let y = 50; y < 100; y++) {

        for (let x = 100; x < 150; x++) {

          let index = 4 * (x + y * width);

          // calculate the differences

          capture.pixels[index] = 255;

          capture.pixels[index+1] = 255;

          capture.pixels[index+2] = 255;

          let rdiff = Math.abs(

            capture.pixels[index + 0] - previousPixels[index + 0]

          );

          let gdiff = Math.abs(

            capture.pixels[index + 1] - previousPixels[index + 1]

          );

          let bdiff = Math.abs(

            capture.pixels[index + 2] - previousPixels[index + 2]

          );

          // copy the current pixels to previousPixels

          previousPixels[index + 0] = capture.pixels[index + 0];

          previousPixels[index + 1] = capture.pixels[index + 1];

          previousPixels[index + 2] = capture.pixels[index + 2];

          let diffs = rdiff + gdiff + bdiff;

​

          if (diffs > thresholdAmount && !currentFile.isPlaying()) {

            currentFile = sounds[Math.floor(random(5))];

            currentFile.play();

          }

        }

      }

    }

  }

capture.updatePixels();  

    image(capture, 0, 0, 640, 480);

}

​