一. 前言

        JRTPLIB 是 C++ 语言编写的 RTP 库，它帮助我们封装了 RTP 协议细节，用户通过提供好的接口可以设置 RTP 包信息并发送到指定地址，也可以接收 RTP 包取出信息。

        本文仅介绍如何使用 JRTPLIB 发送/接收 RTP 数据包，我在这篇博客又介绍了如何使用 JRTPLIB 构造 RTP 数据包来荷载 H264 码流数据。

二. 下载编译安装

git clone https://github.com/j0r1/JRTPLIB.gitcd JRTPLIBcmake CMakeLists.txtmakesudo make install

三. 代码实战

1. JRTPLIB接收RTP包程序

#include <jrtplib3/rtpsession.h>#include <jrtplib3/rtplibraryversion.h>#include <jrtplib3/rtpudpv4transmitter.h>#include <jrtplib3/rtpsessionparams.h>#include <jrtplib3/rtppacket.h>#include <iostream>#include <arpa/inet.h>using namespace jrtplib;void checkerror(int rtperr) {if (rtperr < 0) {std::cout << "ERROR: " << RTPGetErrorString(rtperr) << std::endl;exit(-1);}}int main() {std::cout << "Using JRTPLib version: " << RTPLibraryVersion::GetVersion().GetVersionString() << std::endl;uint16_t localport;std::cout << "Enter local port(even): ";std::cin >> localport;RTPUDPv4TransmissionParams tranparams;tranparams.SetPortbase(localport);RTPSessionParams sessparams;sessparams.SetOwnTimestampUnit(1.0 / 10.0);sessparams.SetAcceptOwnPackets(true);RTPSession sess;int status = sess.Create(sessparams, &tranparams);checkerror(status);RTPTime delay(0.020);RTPTime startTime = RTPTime::CurrentTime();bool done = false;while (!done) {sess.BeginDataAccess();if (sess.GotoFirstSourceWithData()) {do {RTPPacket* packet;while ((packet = sess.GetNextPacket()) != NULL) {std::cout << "Got packet!" << std::endl;std::cout << "SSRC: " << packet->GetSSRC() << std::endl;std::cout << "Payload data: " << packet->GetPayloadData() << std::endl;std::cout << "Payload type: " << packet->GetPayloadType() << std::endl;std::cout << "Packet length: " <<packet->GetPacketLength() << std::endl;std::cout << "Sequence number: " << packet->GetSequenceNumber() << std::endl;std::cout << "Timestamp: " << packet->GetTimestamp() << std::endl;std::cout << std::endl;sess.DeletePacket(packet);} } while (sess.GotoNextSourceWithData());}sess.EndDataAccess();RTPTime::Wait(delay);}sess.EndDataAccess();return 0;}

编译后运行如上，设置本地监听端口后就会开始等待 RTP 数据。

2. JRTPLIB发送RTP包程序

#include <jrtplib3/rtpsession.h>#include <jrtplib3/rtplibraryversion.h>#include <jrtplib3/rtpudpv4transmitter.h>#include <jrtplib3/rtpsessionparams.h>#include <jrtplib3/rtppacket.h>#include <iostream>#include <arpa/inet.h>using namespace jrtplib;void checkerror(int rtperr) {if (rtperr < 0) {std::cout << "ERROR: " << RTPGetErrorString(rtperr) << std::endl;exit(-1);}}int main() {std::cout << "Using JRTPLib version: " << RTPLibraryVersion::GetVersion().GetVersionString() << std::endl;uint16_t localport;std::cout << "Enter local port(even): ";std::cin >> localport;std::string ipstr;std::cout << "Enter the destination IP address: ";std::cin >> ipstr;uint32_t destip = inet_addr(ipstr.c_str());if (destip == INADDR_NONE) {std::cerr << "Bad IP address specified" << std::endl;return -1;}// The inet_addr function returns a value in network byte order, but// we need the IP address in host byte order, so we use a call to// ntohldestip = ntohl(destip);uint16_t destport;std::cout << "Enter the destination port: ";std::cin >> destport;int num;std::cout << "Number of packets you wish to be sent: ";std::cin >> num;RTPUDPv4TransmissionParams tranparams;tranparams.SetPortbase(localport);RTPSessionParams sessparams;sessparams.SetOwnTimestampUnit(1.0 / 10.0);sessparams.SetAcceptOwnPackets(true);// Now, we'll create a RTP session, set the destination, send some// packets and poll for incoming data.RTPSession sess;int status = sess.Create(sessparams, &tranparams);checkerror(status);RTPIPv4Address destAddr(destip, destport);status = sess.AddDestination(destAddr);checkerror(status);sess.SetDefaultPayloadType(96);sess.SetDefaultMark(false);for (int i = 1;i <= num;++i) {std::cout << "Sending packet " << i << "/" << num << std::endl;status = sess.SendPacket((void*)"0123456789", 10, 0, false, 10);checkerror(status);RTPTime::Wait(RTPTime(1, 0));}sess.BYEDestroy(RTPTime(10, 0), 0, 0);return 0;}

        编译后运行如上，输入本地 UDP 使用的端口以及对端监听的端口，设置需要发送的 RTP 包数即可发送，发送后接收端打印的信息如下。