JS 调取摄像头

亦凉 2022-09-21 14:27 158阅读 0赞

## **JS 调取摄像头** ##

截止目前（2016-06-23）为止，js 调取摄像头实现视频聊天，部分浏览器还是不怎么支持的。

### **示例1 ：** ###

代码附上：

<!DOCTYPE html>
    <html>
    
        <head>
            <meta charset="utf-8" />
            <title></title>
            <meta name="viewport" content="width=device-width, initial-scale=1">
    
        </head>
    
        <body>
            <video id="video" width="640" height="480" autoplay></video>
        </body>
        <script type="text/javascript"> var promisifiedOldGUM = function(constraints) { // 第一个拿到getUserMedia，如果存在 var getUserMedia = (navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia); // 有些浏览器只是不实现它-返回一个不被拒绝的承诺与一个错误保持一致的接口 if (!getUserMedia) { return Promise.reject(new Error('getUserMedia is not implemented in this browser-getUserMedia是不是在这个浏览器实现')); } // 否则，调用包在一个旧navigator.getusermedia承诺 return new Promise(function(resolve, reject) { getUserMedia.call(navigator, constraints, resolve, reject); }); } // 旧的浏览器可能无法实现mediadevices可言，所以我们设置一个空的对象第一 if (navigator.mediaDevices === undefined) { navigator.mediaDevices = {}; } // 一些浏览器部分实现mediadevices。我们不能只指定一个对象 // 随着它将覆盖现有的性能getUserMedia。. // 在这里，我们就要错过添加getUserMedia财产。. if (navigator.mediaDevices.getUserMedia === undefined) { navigator.mediaDevices.getUserMedia = promisifiedOldGUM; } // Prefer camera resolution nearest to 1280x720. var constraints = { audio: true, video: { width: 1280, height: 720 } }; navigator.mediaDevices.getUserMedia(constraints) .then(function(stream) { var video = document.querySelector('video'); video.src = window.URL.createObjectURL(stream); video.onloadedmetadata = function(e) { video.play(); }; }).catch(function(err) { console.log(err.name + ": " + err.message); }); </script>
    
    </html>

就拿以上这个代码来说，火狐下是可以正常调取摄像头的。

谷歌下其实也可以，一般 [http://localhost:8080][http_localhost_8080] 或者 [http://172.0.0.1:8080][http_172.0.0.1_8080]服务，这个是可以调起的，但是如果使用 指定的 ip，

比如： [http://172.168.5.100:8080][http_172.168.5.100_8080] ，此时就会报个 PermissionDeniedError: Only secure origins are allowed (see: [https://goo.gl/Y0ZkNV][https_goo.gl_Y0ZkNV]).异常信息提示。

这个所表达的意思在这里：

[http://stackoverflow.com/questions/32329484/google-permission-denied-on-current-location][http_stackoverflow.com_questions_32329484_google-permission-denied-on-current-location]

[http://stackoverflow.com/questions/34290337/serviceworker-registration-failed-domexception-only-secure-origins-are-allowed][http_stackoverflow.com_questions_34290337_serviceworker-registration-failed-domexception-only-secure-origins-are-allowed]

--------------------

### **示例2 ：** ###

<!DOCTYPE html>
    <html>
    
        <head>
            <meta charset="utf-8" />
            <meta name="viewport" content="width=device-width, initial-scale=1">
            <title>js 获取视频 demo</title>
    
        </head>
    
        <body>
            <video id="video" width="640" height="480" autoplay></video>
            <button id="snap">Snap Photo</button>
            <canvas id="canvas" width="640" height="480"></canvas>
        </body>
        <script type="text/javascript"> // Put event listeners into place window.addEventListener("DOMContentLoaded", function() { // Grab elements, create settings, etc. var canvas = document.getElementById("canvas"), context = canvas.getContext("2d"), //getContext唯一合法值2d video = document.getElementById("video"), videoObj = { "video": true, "audio": true }, errBack = function(error) { console.log("Video capture error: ", error.code); }; // Put video listeners into place //navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia; if (navigator.getUserMedia) { // Standard 如果用户允许打开摄像头 //stream为读取的视频流 navigator.getUserMedia(videoObj, function(stream) { video.src = stream; video.play(); }, errBack); } else if (navigator.webkitGetUserMedia) { // WebKit-prefixed 根据不同的浏览器写法不同 navigator.webkitGetUserMedia(videoObj, function(stream) { video.src = window.webkitURL.createObjectURL(stream); video.play(); }, errBack); } else if (navigator.mozGetUserMedia) { // Firefox-prefixed navigator.mozGetUserMedia(videoObj, function(stream) { video.src = window.URL.createObjectURL(stream); video.play(); }, errBack); } document.getElementById("snap").addEventListener("click", function() { context.drawImage(video, 0, 0, 640, 480); }); }, false); </script>
    
    </html>

**PC 浏览器支持：**

![这里写图片描述][20160623200253936]

**Mobile 浏览器支持：**

![这里写图片描述][20160623200408719]

--------------------

[http_localhost_8080]: http://localhost:8080
[http_172.0.0.1_8080]: http://172.0.0.1:8080
[http_172.168.5.100_8080]: http://172.168.5.100:8080
[https_goo.gl_Y0ZkNV]: https://goo.gl/Y0ZkNV
[http_stackoverflow.com_questions_32329484_google-permission-denied-on-current-location]: http://stackoverflow.com/questions/32329484/google-permission-denied-on-current-location
[http_stackoverflow.com_questions_34290337_serviceworker-registration-failed-domexception-only-secure-origins-are-allowed]: http://stackoverflow.com/questions/34290337/serviceworker-registration-failed-domexception-only-secure-origins-are-allowed
[20160623200253936]: /images/20220721/7d6f639177784394ae08478327382e8c.png
[20160623200408719]: /images/20220721/4349f139f96b4a8fa3502c4a748e72cf.png