场景说明
网页指定video属性如下：
<div class="box showBorder black">
<video id="vid2" class="box abs video" autoplay="autoplay" muted></video>
</div>
运行提示出错：
10.375: Failed to createAnswer: OperationError: PeerConnection cannot create an answer in a state other than have-remote-offer or have-local-pranswer.
v.js:70 Uncaught (in promise) DOMException: Failed to parse SessionDescription. a=extmap-allow-mixed Expects at least 2 fields.
运行版本：
解决方案
升级google浏览器
