音视频SDP协议详解（描述会话的协议）
https://baijiahao.baidu.com/s?id=1612136301101655515&wfr=spider&for=pc
https://blog.csdn.net/zhizhengguan/article/details/124152695
https://baijiahao.baidu.com/s?id=1612136301101655515&wfr=spider&for=pc
https://blog.csdn.net/zhizhengguan/article/details/124152695