一、函数调用关系

Thread::PreRun
->Thread::ProcessMessages
->Thread::Dispatch
->Thread::QueuedTaskHandler::OnMessage
->BaseChannel::SetRemoteContent
->VideoChannel::SetRemoteContent_w

----video.streams通过MediaContentDescription获取，MediaContentDescription通过sdp获取
->BaseChannel::UpdateRemoteStreams_w
->WebRtcVideoChannel::AddRecvStream

-----调用ConfigureReceiverRtp配置远端ssrc
->WebRtcVideoChannel::WebRtcVideoReceiveStream::WebRtcVideoReceiveStream
->WebRtcVideoChannel::WebRtcVideoReceiveStream::RecreateWebRtcVideoStream
->internal::Call::CreateVideoReceiveStream

----将远端ssrc,emplace到receive_rtp_config_，后续收包时做合法性判断
->internal::VideoReceiveStream2::VideoReceiveStream2
->RtpVideoStreamReceiver2::RtpVideoStreamReceiver2

----生效远端ssrc

二、具体函数实现

• CreateTracksFromSsrcInfos解析sdp命令行，构造StreamParams参数

 

• ConfigureReceiverRtp配置远端ssrc

• Call::CreateVideoReceiveStream，将远端ssrc,emplace到receive_rtp_config_

• DeliveryStatus Call::DeliverRtp对收到报文的ssrc进行合法性判断 

  

• RtpVideoStreamReceiver2::RtpVideoStreamReceiver2函数生效远端ssrc

•  接收RTCP报文时，使用该值做合法性判断

•    SDP命令行

参见博客 https://blog.csdn.net/CrystalShaw/article/details/80516999

SDP有SSRC的协商