js HTML5 method to capture video from camera based on filter_javascript skills

The example in this article describes the js HTML5 method of capturing video from the camera based on filters. Share it with everyone for your reference. The details are as follows:

index.html page:

<div class="warning">
<h2>Native web camera streaming (getUserMedia) is not supported in this browser.</h2>
</div>
<div class="container">
  <h3>Current filter is: None</h3>
  <button>Click here to change video filter</button>
  <div style="clear:both"></div>
  <div class="col">
    <h2>HTML5 <video> object</h2>
    <video></video>
  </div>
  <div class="col">
    <h2>HTML5 <canvas> object</h2>
    <canvas width="600" height="450"></canvas>
  </div>
</div>

style.css file:

.grayscale{
  -webkit-filter:grayscale(1);
  -moz-filter:grayscale(1);
  -o-filter:grayscale(1);
  -ms-filter:grayscale(1);
  filter:grayscale(1);
}
.sepia{
  -webkit-filter:sepia(0.8);
  -moz-filter:sepia(0.8);
  -o-filter:sepia(0.8);
  -ms-filter:sepia(0.8);
  filter:sepia(0.8);
}
.blur{
  -webkit-filter:blur(3px);
  -moz-filter:blur(3px);
  -o-filter:blur(3px);
  -ms-filter:blur(3px);
  filter:blur(3px);
}
.brightness{
  -webkit-filter:brightness(0.3);
  -moz-filter:brightness(0.3);
  -o-filter:brightness(0.3);
  -ms-filter:brightness(0.3);
  filter:brightness(0.3);
}
.contrast{
  -webkit-filter:contrast(0.5);
  -moz-filter:contrast(0.5);
  -o-filter:contrast(0.5);
  -ms-filter:contrast(0.5);
  filter:contrast(0.5);
}
.hue-rotate{
  -webkit-filter:hue-rotate(90deg);
  -moz-filter:hue-rotate(90deg);
  -o-filter:hue-rotate(90deg);
  -ms-filter:hue-rotate(90deg);
  filter:hue-rotate(90deg);
}
.hue-rotate2{
  -webkit-filter:hue-rotate(180deg);
  -moz-filter:hue-rotate(180deg);
  -o-filter:hue-rotate(180deg);
  -ms-filter:hue-rotate(180deg);
  filter:hue-rotate(180deg);
}
.hue-rotate3{
  -webkit-filter:hue-rotate(270deg);
  -moz-filter:hue-rotate(270deg);
  -o-filter:hue-rotate(270deg);
  -ms-filter:hue-rotate(270deg);
  filter:hue-rotate(270deg);
}
.saturate{
  -webkit-filter:saturate(10);
  -moz-filter:saturate(10);
  -o-filter:saturate(10);
  -ms-filter:saturate(10);
  filter:saturate(10);
}
.invert{
  -webkit-filter:invert(1);
  -moz-filter:invert(1);
  -o-filter: invert(1);
  -ms-filter: invert(1);
  filter: invert(1);
}

script.js file:

// Main initialization
document.addEventListener('DOMContentLoaded', function() {
  // Global variables
  var video = document.querySelector('video');
  var audio, audioType;
  var canvas = document.querySelector('canvas');
  var context = canvas.getContext('2d');
  // Custom video filters
  var iFilter = 0;
  var filters = [
    'grayscale',
    'sepia',
    'blur',
    'brightness',
    'contrast',
    'hue-rotate',
    'hue-rotate2',
    'hue-rotate3',
    'saturate',
    'invert',
    'none'
  ];
  // Get the video stream from the camera with getUserMedia
  navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia ||
    navigator.mozGetUserMedia || navigator.msGetUserMedia;
  window.URL = window.URL || window.webkitURL || window.mozURL || window.msURL;
  if (navigator.getUserMedia) {
    // Evoke getUserMedia function
    navigator.getUserMedia({video: true, audio: true}, onSuccessCallback, onErrorCallback);
    function onSuccessCallback(stream) {
      // Use the stream from the camera as the source of the video element
      video.src = window.URL.createObjectURL(stream) || stream;
      // Autoplay
      video.play();
      // HTML5 Audio
      audio = new Audio();
      audioType = getAudioType(audio);
      if (audioType) {
        audio.src = 'polaroid.' + audioType;
        audio.play();
      }
    }
    // Display an error
    function onErrorCallback(e) {
      var expl = 'An error occurred: [Reason: ' + e.code + ']';
      console.error(expl);
      alert(expl);
      return;
    }
  } else {
    document.querySelector('.container').style.visibility = 'hidden';
    document.querySelector('.warning').style.visibility = 'visible';
    return;
  }
  // Draw the video stream at the canvas object
  function drawVideoAtCanvas(obj, context) {
    window.setInterval(function() {
      context.drawImage(obj, 0, 0);
    }, 60);
  }
  // The canPlayType() function doesn't return true or false. In recognition of how complex
  // formats are, the function returns a string: 'probably', 'maybe' or an empty string.
  function getAudioType(element) {
    if (element.canPlayType) {
      if (element.canPlayType('audio/mp4; codecs="mp4a.40.5"') !== '') {
        return('aac');
      } else if (element.canPlayType('audio/ogg; codecs="vorbis"') !== '') {
        return("ogg");
      }
    }
    return false;
  }
  // Add event listener for our video's Play function in order to produce video at the canvas
  video.addEventListener('play', function() {
    drawVideoAtCanvas(this, context);
  }, false);
  // Add event listener for our Button (to switch video filters)
  document.querySelector('button').addEventListener('click', function() {
    video.className = '';
    canvas.className = '';
    var effect = filters[iFilter++ % filters.length]; // Loop through the filters.
    if (effect) {
      video.classList.add(effect);
      canvas.classList.add(effect);
      document.querySelector('.container h3').innerHTML = 'Current filter is: ' + effect;
    }
  }, false);
}, false);

I hope this article will be helpful to everyone’s JavaScript programming design.