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前言
GB/T28181-2022实时流的传输方式介绍：https://blog.csdn.net/www_dong/article/details/134255185
基于jrtplib实现tcp被动和主动收流介绍：https://blog.csdn.net/www_dong/article/details/134451387
本文主要介绍下级平台或设备发流功能，用于对接特定的SIP服务器或上级平台。
UDP发流
流程图
发送端流程：
- 初始化rtp参数；
- 裸流数据做PS复用；
- 组RTP包发送；
设计
- 初始化rtp参数
int CUdp::InitRtp_()
{RTPSessionParams sessionParams;sessionParams.SetMinimumRTCPTransmissionInterval(10);sessionParams.SetOwnTimestampUnit(1.0 / 90000.0);sessionParams.SetAcceptOwnPackets(true);sessionParams.SetMaximumPacketSize(1450);RTPUDPv4TransmissionParams transParams;transParams.SetRTPSendBuffer(2*1024*1024);transParams.SetBindIP(m_ip);transParams.SetPortbase((uint16_t)m_port);if (0 != Create(sessionParams, &transParams)){return -1;}SetDefaultPayloadType((uint8_t)m_payload);SetDefaultTimestampIncrement(3600);SetDefaultMark(true);RTPIPv4Address addr(ntohl(inet_addr(m_ip), (uint16_t)m_port);if(0 != AddDestination(addr)){return -1;}return 0;
}
- 流数据复用为PS
// 使用ireader开源库进行ps复用
// 初始化
CData2PS::CData2PS()
{struct ps_muxer_func_t func;func.alloc = Alloc;func.free = Free;func.write = Packet;m_ps = ps_muxer_create(&func, this);// TODO codecid待补充m_ps_stream = ps_muxer_add_stream(m_ps, PSI_STREAM_H264, nullptr, 0);
}// 塞数据
int CData2PS::InputData(void* data, int len)
{if (!m_ps)return -1;uint64_t clock = time64_now();if (0 == m_ps_clock)m_ps_clock = clock;return ps_muxer_input(m_ps, m_ps_stream, 0, (clock - m_ps_clock) * 90, (clock - m_ps_clock) * 90, data, len);
}
- 发送rtp包
// 调用jrtplib中SendPacket(data, len);接口发送数据// 以下为SendPacket部分源码
// 主要流程:
// 1. 构建packet
// 2. 发送rtp数据
int RTPSession::SendPacket(const void *data,size_t len,uint8_t pt,bool mark,uint32_t timestampinc)
{int status;if (!created)return ERR_RTP_SESSION_NOTCREATED;BUILDER_LOCKif ((status = packetbuilder.BuildPacket(data,len,pt,mark,timestampinc)) < 0){BUILDER_UNLOCKreturn status;}if ((status = SendRTPData(packetbuilder.GetPacket(),packetbuilder.GetPacketLength())) < 0){BUILDER_UNLOCKreturn status;}BUILDER_UNLOCKSOURCES_LOCKsources.SentRTPPacket();SOURCES_UNLOCKPACKSENT_LOCKsentpackets = true;PACKSENT_UNLOCKreturn 0;
}// 构建包
int RTPPacketBuilder::PrivateBuildPacket(const void *data,size_t len,uint8_t pt,bool mark,uint32_t timestampinc,bool gotextension,uint16_t hdrextID,const void *hdrextdata,size_t numhdrextwords)
{RTPPacket p(pt,data,len,seqnr,timestamp,ssrc,mark,numcsrcs,csrcs,gotextension,hdrextID,(uint16_t)numhdrextwords,hdrextdata,buffer,maxpacksize,GetMemoryManager());int status = p.GetCreationError();if (status < 0)return status;packetlength = p.GetPacketLength();if (numpackets == 0) // first packet{lastwallclocktime = RTPTime::CurrentTime();lastrtptimestamp = timestamp;prevrtptimestamp = timestamp;}else if (timestamp != prevrtptimestamp){lastwallclocktime = RTPTime::CurrentTime();lastrtptimestamp = timestamp;prevrtptimestamp = timestamp;}numpayloadbytes += (uint32_t)p.GetPayloadLength();numpackets++;timestamp += timestampinc;seqnr++;return 0;
}// 发送包
int RTPSession::SendRTPData(const void *data, size_t len)
{if (!m_changeOutgoingData)return rtptrans->SendRTPData(data, len);void *pSendData = 0;size_t sendLen = 0;int status = 0;status = OnChangeRTPOrRTCPData(data, len, true, &pSendData, &sendLen);if (status < 0)return status;if (pSendData){status = rtptrans->SendRTPData(pSendData, sendLen);OnSentRTPOrRTCPData(pSendData, sendLen, true);}return status;
}// 底层实现
int RTPUDPv4Transmitter::SendRTPData(const void *data,size_t len)
{if (!init)return ERR_RTP_UDPV4TRANS_NOTINIT;MAINMUTEX_LOCKif (!created){MAINMUTEX_UNLOCKreturn ERR_RTP_UDPV4TRANS_NOTCREATED;}if (len > maxpacksize){MAINMUTEX_UNLOCKreturn ERR_RTP_UDPV4TRANS_SPECIFIEDSIZETOOBIG;}destinations.GotoFirstElement();while (destinations.HasCurrentElement()){// 调用sendto函数实现udp包的发送sendto(rtpsock,(const char *)data,len,0,(const struct sockaddr *)destinations.GetCurrentElement().GetRTPSockAddr(),sizeof(struct sockaddr_in));destinations.GotoNextElement();}MAINMUTEX_UNLOCKreturn 0;
}
tcp passive发流
流程图
发送端流程：
- 上级平台或sip服务器以主动方式连接，对于下级平台或者设备（数据发送端）为被动方式；
- 下级平台或者设备（数据发送端）启动端口监听；
- 接收上级平台或sip服务器tcp连接请求；
- 向上级平台或sip服务器发送流数据；
设计
- 创建socket、bind、listen，启动数据接收线程；
// TcpServer为封装的socket类int CGBTcpServer::Start()
{if (0 != m_localPort || m_tcpServer.get())return 0;int ret = -1;do {m_tcpServer = std::make_shared<TcpServer>(nullptr, this);if (!m_tcpServer.get())break;ret = m_tcpServer->TcpCreate();if (0 != ret)break;ret = m_tcpServer->TcpBind(m_localPort);if (0 != ret)break;ret = m_tcpServer->TcpListen(5);if (0 != ret)break;m_thread = std::thread(TCPData2PSThread, this);return 0;} while (0);Stop();return ret;
}
- 在线程内等待连接，连接成功后接收数据并回调至应用层处理
void CGBTcpServer::TCPData2PSWorker()
{if (!m_pspacker)m_pspacker = new(std::nothrow) CData2PS(PSTCPDataCB, this);bool bAccept = false;while (m_running){if (!bAccept){if (0 == m_tcpServer->TcpAccept()){bAccept = true;if (0 != InitRtp_()){break;}}continue;}std::this_thread::sleep_for(std::chrono::seconds(1));}
}
- 初始化rtp参数
int CGBTcpServer::InitRtp_()
{const int packetSize = 45678;RTPSessionParams sessionparams;sessionparams.SetProbationType(RTPSources::NoProbation);sessionparams.SetOwnTimestampUnit(1.0 / packetSize);sessionparams.SetMaximumPacketSize(packetSize + 64);m_rtpTcpTransmitter = new RTPTCPTransmitter(nullptr);m_rtpTcpTransmitter->Init(true);m_rtpTcpTransmitter->Create(65535, 0);int status = Create(sessionparams, m_rtpTcpTransmitter);if (status < 0){return status;}status = AddDestination(RTPTCPAddress(m_tcpServer->GetClientSocket()));if (0 != status)return status;SetDefaultPayloadType(96);SetDefaultMark(false);SetDefaultTimestampIncrement(160);return 0;
}
- 将数据复用为PS；
- tcp方式发包
// 调用jrtplib中SendPacket(data, len);接口发送数据// 以下为tcp方式SendPacket部分源码
int RTPTCPTransmitter::SendRTPData(const void *data,size_t len)
{return SendRTPRTCPData(data, len);
}int RTPTCPTransmitter::SendRTPRTCPData(const void *data, size_t len)
{if (!m_init)return ERR_RTP_TCPTRANS_NOTINIT;MAINMUTEX_LOCKif (!m_created){MAINMUTEX_UNLOCKreturn ERR_RTP_TCPTRANS_NOTCREATED;}// #define RTPTCPTRANS_MAXPACKSIZE 65535if (len > RTPTCPTRANS_MAXPACKSIZE){MAINMUTEX_UNLOCKreturn ERR_RTP_TCPTRANS_SPECIFIEDSIZETOOBIG;}std::map<SocketType, SocketData>::iterator it = m_destSockets.begin();std::map<SocketType, SocketData>::iterator end = m_destSockets.end();vector<SocketType> errSockets;int flags = 0;
#ifdef RTP_HAVE_MSG_NOSIGNALflags = MSG_NOSIGNAL;
#endif // RTP_HAVE_MSG_NOSIGNALwhile (it != end){uint8_t lengthBytes[2] = { (uint8_t)((len >> 8)&0xff), (uint8_t)(len&0xff) };SocketType sock = it->first;// 调用send接口发送数据// 1. 先发送2字节头(固定格式)// 2. 再发送数据if (send(sock,(const char *)lengthBytes,2,flags) < 0 ||send(sock,(const char *)data,len,flags) < 0)errSockets.push_back(sock);++it;}MAINMUTEX_UNLOCKif (errSockets.size() != 0){for (size_t i = 0 ; i < errSockets.size() ; i++)OnSendError(errSockets[i]);}// Don't return an error code to avoid the poll thread exiting// due to one closed connection for examplereturn 0;
}
tcp active发流
流程图
发送端流程：
- 上级平台或sip服务器启动tcp监听连接，对于下级平台或者设备（数据发送端）为主动方式；
- 下级平台或者设备（数据发送端）发起tcp连接；
- 接收上级平台或sip服务器tcp响应；
- 向上级平台或sip服务器发送流数据；
设计
- 创建socket、connect、初始化rtp，启动数据接收线程
// TcpClient为封装的客户端socket类int CGBTcpClient::Start()
{if (0 != m_localPort || m_tcpClient.get())return 0;int ret = -1;do{m_tcpClient = std::make_shared<TcpClient>(nullptr, this);if (!m_tcpClient.get() || 0 != m_tcpClient->TcpCreate())break;ret = m_tcpClient->TcpConnectByTime(m_localIP.c_str(), m_localPort, 5);if (0 != ret)break;ret = InitRtp_();if (0 != ret)break;m_thread = std::thread(RTPPackerThread, this);return 0;} while (0);Stop();return ret;
}
- 初始化rtp参数
int CGBTcpClient::InitRtp_()
{const int packSize = 45678;RTPSessionParams sessionParams;sessionParams.SetProbationType(RTPSources::NoProbation);sessionParams.SetOwnTimestampUnit(90000.0 / 25.0);sessionParams.SetMaximumPacketSize(packSize + 64);m_rtpTcpTransmitter = new RTPTCPTransmitter(nullptr);m_rtpTcpTransmitter->Init(true);m_rtpTcpTransmitter->Create(65535, 0);if (0 != Create(sessionParams, m_rtpTcpTransmitter))return -1;if (0 != AddDestination(RTPTCPAddress(m_tcpClient->GetClientSocket())))return -1;return 0;
}
- 视音频数据复用为PS
- 发送数据，同tcp passive发流