js and HTML5 filter based method of capturing video from camera

This article mainly introduces the js HTML5 method of capturing video from the camera based on filters, and involves the use of javascript to operate multimedia based on html5 elements. Friends in need can refer to it

The examples in this article describe js HTML5 is a filter-based approach to capturing video from a webcam. Share it with everyone for your reference. The details are as follows:

index.html page:

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

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);

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