WebRTC(三) Web端音视频设备信息获取

本文介绍如果在浏览器中获取音视频的设备信息，并在html页面中显示设备信息。

文章目录

通过js代码获取设备信息可以通过如下方法

var ePromise = navigator.mediaDevices.emurateDevices

该方法会返回一个Promise对象，Promise有两个回调方法，then和catch。Promise也可以连续的调用then和catch方法。
例如：获取到音频设备信息接下来执行gotDevices方法，获取失败执行handleError方法。

navigator.mediaDevices.emurateDevices
	.then(gotDevices)
	.catch(handleError);

获取音频设备信息最终会返回一个MediaDevicesInfo对象，MediaDevicesInfo对象有四个属性

deviceID：设备id
label：设备名字
kind：设备种类，
goupID：两个设备groupID相同说明是同一个设备

以下是通过js获取设备信息并在html页面显示的完整示例：

1 html代码，用于显示当前设备的信息

<html>
	<head>
		<title>WebRTC get audio and video devices</title>
	</head>
	<body>
		<div>
			 <label>audio input device:</label>
             <select id = "audioSource"></select>
		</div>
		<div>
			<label>audio output device:</label>
			<select id = "audioOutput"></select>
		</div>	
		<div>
			<label>video input device:</label>
			<select id = "videoSource"></select>
		</div>
		<script src="client.js"></script>
	</body>
</html>

2 js代码，用于获取当前设备信息

'use strict'
var audioSource = document.querySelector("select#audioSource");
var audioOutput = document.querySelector("select#audioOutput");
var videoSource = document.querySelector("select#videoSource");

if(!navigator.mediaDevices || !navigator.mediaDevices.emurateDevices){
	console.log('emurateDevices is not support!');
}else{
	navigator.mediaDevices.emurateDevices
	.then(gotDevices)
	.catch(handleError);
}

function gotDevices(devicesInfo){
	devicesInfos.forEash(function(deviceInfo)){
		console.log(deviceInfo.kind 
			+ ": label = "+deviceInfo.label
			+ ": id  = " + deviceInfo.deviceId
			+ ": groupId = " + deviceInfo.groupId);

		var option = document.createElement('option');
		option.html = deviceInfo.label;
		option.value = deviceInfo.deviceId;

		if(deviceInfo.kind === 'audioinput'){
				audioSource.appendChild(option);
		}else if(deviceInfo.kind === 'audiooutput'){
				audioOutput.appendChild(option);
		}else if(deviceInfo.kind === 'videoinput'){
				videoSource.appendChild(option);
		}
	}
}

function handleError(err){
	console.log(err.name + “ ： ” + err.message);
}

3 js打印结果

audioinput: label = : id = default: groupId = c8c3ef9c92cf11acba2a3a50b317b9bf2cf30f5d401f9874445ed51e731ef4bd
client.js:17 audioinput: label = : id = b12c633cd7017ae872295cc07950aa4f72c8dfcbb038481cda0a0ef3d0cc2f09: groupId = c8c3ef9c92cf11acba2a3a50b317b9bf2cf30f5d401f9874445ed51e731ef4bd
client.js:17 videoinput: label = : id = b95c88c72235c31f445c13258cdb2d4ab5a774225b3757281d58b453fc14b0c0: groupId = cb329ecdbf1a92f2eadd2c3c5e6ca0cfbdb6a2ae3f93d5a2967c830444503c4b
client.js:17 audiooutput: label = : id = default: groupId = c8c3ef9c92cf11acba2a3a50b317b9bf2cf30f5d401f9874445ed51e731ef4bd
client.js:17 audiooutput: label = : id = a8c76b962c5b479073378dbde69fcf8edc05f125aa58d885a231bfc608c0cae2: groupId = c8c3ef9c92cf11acba2a3a50b317b9bf2cf30f5d401f9874445ed51e731ef4bd

可以看到label没有值，这是因为没有获取到音频设备的权限。
通过下一节调用如下方法即可拿到权限。

4 获取权限方法

navigator.mediaDevices.getUserMedia

权限允许后日志结果为

audioinput: label = 默认 - Internal Microphone (Built-in): id  = default: groupId = 82e27b59443e601531ee473f9bce5f91ccf6e94e149c9a6340e4e967668b3ff5
client.js:16 audioinput: label = Internal Microphone (Built-in): id  = 2fd08ea727e78ddff0bffc60371b2f3e32ebcae6633124eadb45acb5a1f99a50: groupId = 82e27b59443e601531ee473f9bce5f91ccf6e94e149c9a6340e4e967668b3ff5
client.js:16 videoinput: label = FaceTime HD Camera: id  = 538df4b814a02ff9eadab3eb67facada3f45dec55613a9d8f11a4af024483a19: groupId = 5f5b792a90446a6c3e25aafec72960de9363a7f72255bc50a191ad2055c7b555
client.js:16 audiooutput: label = 默认 - Internal Speakers (Built-in): id  = default: groupId = 82e27b59443e601531ee473f9bce5f91ccf6e94e149c9a6340e4e967668b3ff5
client.js:16 audiooutput: label = Internal Speakers (Built-in): id  = 179e0539b0b7b2ec359d3d89d1d93372ffcf0d7154f106062c70f9548499621a: groupId = 82e27b59443e601531ee473f9bce5f91ccf6e94e149c9a6340e4e967668b3ff5