在线的测试Demo：https://webrtc.github.io/samples/src/content/devices/input-output/ 摄像头列表选择后置摄像头，微信浏览器上开启失败，手机系统浏览器上能打开

https://developers.weixin.qq.com/miniprogram/dev/framework/ <live-pusher wx:if="{{rtmpUrl!==''}}" wx:key="livePusher" style="display:inline-block;aspect="16:9" mode="RTC" enable-agc="true" enable-ans="true" orientation="{{orientation}}" url="{{rtmpUrl}}" enable-mic="{{enableMic}}" enable-camera="{{enableCamera}}" muted="{{!enableMic}}" beauty="{{beauty}}" waiting-image="../../images/cover.png" background-mute= "true" max-bitrate="{{maxBitrate}}" min-bitrate="{{minBitrate}}" bindstatechange="pusherStateChangeHandler" bindnetstatus="pusherNetstatusHandler" binderror="pusherErrorHandler" autopush="true" >