约束
-
width : 宽度约束
-
height :高度约束
-
aspectRatio: 比率
-
frameRate: 帧率
-
facingMode ： 摄像头控制
- user:前置摄像头
- environment :后摄像头
- left ： 前置左摄像头
- right：前置右摄像头
-
resizeMode: 采集的画面需不需要裁剪
实战案例
vim index.html
<html>
<head>
<title>WebRTC 获取视频和音频</title>
</head>
<body>
<div>
<label>audio Source:</label>
<select id="audioSource"> </select>
</div>
<div>
<label>audio Output:</label>
<select id="audioOutput"> </select>
</div>
<div>
<label>video Source:</label>
<select id="videoSource"> </select>
</div>
<video autoplay playsinline id="player"></video>
<script src="http://webrtc.github.io/adapter/adapter-latest.js"></script>
<script src="./js/client.js"></script>
</body>
</html>
vim client.js
"use strict"
// 获取设备
var audioSource = document.querySelector("select#audioSource");
var audioOutput = document.querySelector("select#audioOutput");
var videoSource = document.querySelector("select#videoSource");
// 查找视频播放的标签
var videoplay = document.querySelector("video#player");
if (!navigator.mediaDevices || !navigator.mediaDevices.getUserMedia){
console.log("获取音视频方法不存在");
}else{
//---------------- 主要进行约束的地方- -----------------
var constraints = {
video : {
// 宽度在300 - 640之间进行自适应
width : {
min: 300,
max: 640,
},
height: 480,
frameRate： 15
facingMode: enviroment // 设置为前置摄像头
},
audio : false
};
navigator.mediaDevices.getUserMedia(constraints)
.then(gotMediaStream).then(gotDevices)
.catch(handleError);
}
function gotMediaStream(stream){
// 复制流到video标签
videoplay.srcObject = stream;
// 获取流成功之后还可以继续操作
return navigator.mediaDevices.enumerateDevices();
}
function handleError(err){
console.log("错误啦：", err)
}
function gotDevices(deviceInfos){
deviceInfos.forEach(function(deviceinfo){
var option = document.createElement("option");
option.text = deviceinfo.label;
option.value = deviceinfo.deviceId;
// 音频输入
if(deviceinfo.kind === "audioinput"){
audioSource.appendChild(option);
// 音频输出
}else if(deviceinfo.kind === "audiooutput"){
audioOutput.appendChild(option);
// 视频输入
}else if(deviceinfo.kind === "videoinput"){
videoSource.appendChild(option);
}
})
}