JS 调取摄像头

White feathe

发布于 2021-12-08 15:02:43

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发布于 2021-12-08 15:02:43

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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 或者 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 ，此时就会报个 PermissionDeniedError: Only secure origins are allowed (see: 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/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：