转载地址：http://blog.csdn.net/doitsjz/article/details/52462252
WebRtcSession::SetLocalDescription|WebRtcSession::SetRemoteDescription->
WebRtcSession::CreateChannels->WebRtcSession::CreateVoiceChannel|WebRtcSession::CreateVideoChannel->ChannelManager::CreateVideoChannel|
WebRtcSession::CreateDataChannel->
VoiceChannel::Init|VideoChannel::Init|DataChannel::Init->BaseChannel::Init->
BaseChannel::SetTransport->BaseChannel::set_transport_channel->
BaseChannel::ConnectToTransportChannel[SignalReadPacket.connect(this, &BaseChannel::OnChannelRead)]->
BaseChannel::OnChannelRead[从网络读取RTP包]->BaseChannel::HandlePacket[webrtc.pc]->
WebRtcVoiceMediaChannel::OnPacketReceived|WebRtcVideoChannel2::OnPacketReceived->
Call::DeliverPacket->
Call::DeliverRtp->AudioReceiveStream::DeliverRtp|VideoReceiveStream::DeliverRtp->
RtpStreamReceiver::DeliverRtp->
Channel::ReceivePacket[音频]|RtpStreamReceiver::ReceivePacket[webrtc.video视频]->
RtpReceiverImpl::IncomingRtpPacket->RTPReceiverVideo::ParseRtpPacket[视频]->
RtpStreamReceiver::OnReceivedPayloadData->
VideoReceiver::IncomingPacket->VCMReceiver::InsertPacket->
VCMJitterBuffer::InsertPacket->VCMFrameBuffer::InsertPacket->
VCMSessionInfo::InsertPacket[按seqNum插入RTP包 PacketList]->