<!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>
