js和HTML5基于过滤器从摄像头中捕获视频的方法

本文实例讲述了js+HTML5基于过滤器从摄像头中捕获视频的方法。分享给大家供大家参考。具体如下：

index.html页面：

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

style.css文件：

.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 文件：

// 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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