webrtc学习笔记2
音视频采集和播放
打开摄像头并将画面显示到页面
1. 初始化button、video控件
2. 绑定“打开摄像头”响应事件onOpenCamera
3. 如果要打开摄像头则点击 “打开摄像头”按钮,以触发onOpenCamera事件的调用
4. 当触发onOpenCamera调用时
a. 设置约束条件,即是getUserMedia函数的入参
b. getUserMedia有两种情况,一种是正常打开摄像头,使用handleSuccess处理;一种是打开摄像头失败,使
用handleError处理
c. 当正常打开摄像头时,则将getUserMedia返回的stream对象赋值给video控件的srcObject即可将视频显示出
来
<!DOCTYPE html>
<html ><body ><video id="local-video" autoplay playsinline></video><button id="showVideo" >打开摄像头</button><p>通过getUserMedia()获取视频</p></body><script >const constraints = {audio: false,video: true};// 处理打开摄像头成功function handleSuccess(stream) {const video = document.querySelector("#local-video");video.srcObject = stream;}// 异常处理function handleError(error) {console.error("getUserMedia error: " + error);}function onOpenCamera(e) {navigator.mediaDevices.getUserMedia(constraints).then(handleSuccess).catch(handleError);}document.querySelector("#showVideo").addEventListener("click", onOpenCamera);</script>
</html>
打开麦克风并在页面播放捕获的声音
1. 初始化button、audio控件
2. 绑定“打开麦克风”响应事件onOpenMicrophone
3. 如果要打开麦克风则点击 “打开麦克风”按钮,以触发onOpenMicrophone事件的调用
4. 当触发onOpenCamera调用时
a. 设置约束条件,即是getUserMedia函数的入参
b. getUserMedia有两种情况,一种是正常打开麦克风,使用handleSuccess处理;一种是打开麦克风失败,使
用handleError处理
c. 当正常打开麦克风时,则将getUserMedia返回的stream对象赋值给audio控件的srcObject即可将声音播放出
来
<!DOCTYPE html><html><body><audio id="local‐audio" autoplay controls>播放麦克风捕获的声音</audio><button id="playAudio">打开麦克风</button><p>通过getUserMedia()获取音频</p></body> <script>const constraints={audio:true,video:false};//处理打开麦克风成功function handleSuccess(stream){const audio =document.querySelector("#local-audio");audio.srcObject=stream;}// 异常处理function handleError(error){console.error("getUserMedia error: " + error);}function onOpenMicro(e) {navigator.mediaDevices.getUserMedia(constraints).then(handleSuccess).catch(handleError);}document.querySelector("#playAudio").addEventListener("click", onOpenMicrophone);</script> </html>
打开摄像头和麦克风
主要区别是
const constraints = (window.constraints = {audio: true,video: true});
<!DOCTYPE html>
<html><body>//muted消除回声<video id="local‐video" autoplay playsinline muted></video><button id="showVideo">打开音视频</button><div id="errorMsg"></div><p>通过 <code>getUserMedia()</code> 获取音视频.</p><script>const constraints = (window.constraints = {audio: true,video: true});// 处理打开摄像头+麦克风成功function handleSuccess(stream) {const video = document.querySelector("#local‐video");video.srcObject = stream;}function handleError(error) {console.error("getUserMedia error: " + error);}async function onOpenAV(e) {navigator.mediaDevices.getUserMedia(constraints).then(handleSuccess).catch(handleError);}document.querySelector("#showVideo").addEventListener("click",onOpenAV);</script></body>
</html>