http://bashell.nodemedia.cn/archives/webrtc-research-series-2-get-through-webrtc-and-rtmp.html
https://zhuanlan.zhihu.com/p/47302561
https://webrtc.github.io/samples/
https://webrtc.github.io/samples/src/content/capture/video-pc/
https://webrtc.github.io/samples/src/content/peerconnection/multiple/