一、说明
RTP 现在的问题是要解决的流媒体的实时传输的问题的最佳方法。和JRTPLIB 是一个用C++语言实现的RTP库。包含UDP通讯。刚使用JRTPLIB，对JRTPLIB的理解还不够深，当做使用时，积累的一些经验写个笔记吧。
二、RTP协议
实时传送协议（Real-time Transport Protocol或简写RTP，也能够写成RTTP）是一个网络传输协议，RTP协议具体说明了在互联网上传递音频和视频的标准数据包格式。它一開始被设计为一个多播协议。但后来被用在非常多单播应用中。
RTP协议经常使用于流媒体系统（配合RTCP协议或者RTSP协议）。由于RTP自身具有Time stamp所以在ffmpeg 中被用做一种formate。
RTP协议的具体介绍，请參考这篇文章http://www.360doc.com/content/11/1009/15/496343_154624612.shtml
三、RTPSession类
这里不介绍jrtplib的编译安装。这个非常easy，网上非常多地方都有解说。
jrtplib的使用中，主要是环绕这个类来实现的，因此大家有必要去查看源代码，看这类的实现。为了方便使用，我在这做了RTPSession的继承封装。以下直接贴代码了。
RTPSessionUtils.h
#include "rtpsession.h"
#include "rtppacket.h"
#include "rtpudpv4transmitter.h"
#include "rtpipv4address.h"
#include "rtpsessionparams.h"
#include "rtperrors.h"
#ifndef WIN32
#include <netinet/in.h>
#include <arpa/inet.h>
#else
#include <winsock2.h>
#endif // WIN32
#include "rtpsourcedata.h"
#include <stdlib.h>
#include <stdio.h>
#include <iostream>
#include <string>//jrtplib应用需链接的lib
#pragma comment(lib,"ws2_32.lib")
#pragma comment(lib, "jrtplib_d.lib")
#pragma comment(lib,"jthread_d.lib")namespace jrtplib
{class RTPSessionUtils : public RTPSession{typedef RTPSession base_type;public:RTPSessionUtils();~RTPSessionUtils();int AddDestination(const std::string& ip, uint16_t port);int DeleteDestination(const std::string& ip, uint16_t port);int CreateDefault(uint16_t port);protected:void OnNewSource(RTPSourceData *dat);void OnBYEPacket(RTPSourceData *dat);void OnRemoveSource(RTPSourceData *dat);void OnRTPPacket(RTPPacket *pack,const RTPTime &receivetime,const RTPAddress *senderaddress);void OnRTCPCompoundPacket(RTCPCompoundPacket *pack,const RTPTime &receivetime,const RTPAddress *senderaddress);void OnPollThreadStep();private:int GetAddrFromSource(RTPSourceData *dat, uint32_t& ip, uint16_t& port);};
}//整形的ip转成字符串ip
static std::string IPToString(const unsigned int iIP)
{struct in_addr inaddr;inaddr.s_addr = htonl(iIP);return std::string(inet_ntoa(inaddr));
}//字符串ip转成整形ip
static unsigned int IPToInt(const std::string& sIP)
{return inet_addr(sIP.c_str());
}RTPSessionUtils.cpp
#include "RTPSessionUtils.h"namespace jrtplib{RTPSessionUtils::RTPSessionUtils(){
#ifdef WIN32WSADATA dat;WSAStartup(MAKEWORD(2,2),&dat);
#endif // WIN32}RTPSessionUtils::~RTPSessionUtils(){
#ifdef WIN32WSACleanup();
#endif // WIN32}int RTPSessionUtils::CreateDefault(uint16_t port){RTPUDPv4TransmissionParams transparams;RTPSessionParams sessparams;sessparams.SetOwnTimestampUnit(1.0/10.0);//必须设置transparams.SetPortbase(port);//port必须是偶数return base_type::Create(sessparams, &transparams);base_type::SetDefaultPayloadType(0);base_type::SetDefaultTimestampIncrement(0);base_type::SetDefaultMark(false);}int RTPSessionUtils::AddDestination(const std::string& ip, uint16_t port){return base_type::AddDestination(RTPIPv4Address(ntohl(inet_addr(ip.c_str())), port));}int RTPSessionUtils::DeleteDestination(const std::string& ip, uint16_t port){return base_type::DeleteDestination(RTPIPv4Address(ntohl(inet_addr(ip.c_str())), port));}int RTPSessionUtils::GetAddrFromSource(RTPSourceData *dat, uint32_t& ip, uint16_t& port){if (dat->IsOwnSSRC())return -1;if (dat->GetRTPDataAddress() != 0){const RTPIPv4Address *addr = (const RTPIPv4Address *)(dat->GetRTPDataAddress());ip = addr->GetIP();port = addr->GetPort();}else if (dat->GetRTCPDataAddress() != 0){const RTPIPv4Address *addr = (const RTPIPv4Address *)(dat->GetRTCPDataAddress());ip = addr->GetIP();port = addr->GetPort()-1;}return 0;}void RTPSessionUtils::OnNewSource(RTPSourceData *dat){uint32_t ip;uint16_t port;if (GetAddrFromSource(dat, ip, port))return;RTPIPv4Address dest(ip,port);base_type::AddDestination(dest);std::cout << "OnNewSource Adding destination " << IPToString(ip) << ":" << port << std::endl;}void RTPSessionUtils::OnRemoveSource(RTPSourceData *dat){if (dat->ReceivedBYE())return;uint32_t ip;uint16_t port;if (GetAddrFromSource(dat, ip, port))return;RTPIPv4Address dest(ip,port);base_type::DeleteDestination(dest);std::cout << "OnRemoveSource Deleting destination " << IPToString(ip) << ":" << port << std::endl;}void RTPSessionUtils::OnBYEPacket(RTPSourceData *dat){uint32_t ip;uint16_t port;if (GetAddrFromSource(dat, ip, port))return;RTPIPv4Address dest(ip,port);base_type::DeleteDestination(dest);std::cout << "OnBYEPacket Deleting destination " << IPToString(ip) << ":" << port << std::endl;}//仅仅要有rtp包就会触发void RTPSessionUtils::OnRTPPacket(RTPPacket *pack,const RTPTime &receivetime,const RTPAddress *senderaddress){std::cout << "OnRTPPacket: data:" << pack->GetPayloadData() << std::endl;}//收到rtcp包触发void RTPSessionUtils::OnRTCPCompoundPacket(RTCPCompoundPacket *pack,const RTPTime &receivetime,const RTPAddress *senderaddress){std::cout << "OnRTCPCompoundPacket: data:" << pack->GetCompoundPacketData() << std::endl;}//隔段时间就会触发,也能够用于收包回调函数//void RTPSessionUtils::OnPollThreadStep()//{// BeginDataAccess();// // check incoming packets// if (GotoFirstSourceWithData())// {// do// {// RTPPacket *pack;// RTPSourceData *srcdat;// srcdat = GetCurrentSourceInfo();// while ((pack = GetNextPacket()) != NULL)// {// std::cout << "Got packet " << pack->GetExtendedSequenceNumber() << " from SSRC " << srcdat->GetSSRC() << std::endl;// DeletePacket(pack);// }// } while (GotoNextSourceWithData());// }// EndDataAccess();//}
}server.cpp
#include <iostream>
#include "RTPSessionUtils.h"
using namespace jrtplib;
void main()
{int status;RTPSessionUtils sess;status = sess.CreateDefault(8888);if(status){std::cout << "RTP error:" << RTPGetErrorString(status) << std::endl;return;}while (1){std::string buf;std::cout << "Input send data:" ;std::cin >> buf;sess.SendPacket((void*)buf.c_str(), buf.length(), 0, false, 0);if(status){std::cout << "RTP error:" << RTPGetErrorString(status) << std::endl;continue;}}system("pause");
}client.cpp
#include <iostream>
#include "RTPSessionUtils.h"
using namespace jrtplib;void main()
{int status;RTPSessionUtils sess;status = sess.CreateDefault(6666);if(status){std::cout << "RTP error:" << RTPGetErrorString(status) << std::endl;return;}status = sess.AddDestination("127.0.0.1", 8888);if(status){std::cout << "RTP error:" << RTPGetErrorString(status) << std::endl;return;}while (1){std::string buf;std::cout << "Input send data:" ;std::cin >> buf;sess.SendPacket((void*)buf.c_str(), buf.length(), 0, false, 0);if(status){std::cout << "RTP error:" << RTPGetErrorString(status) << std::endl;continue;}}system("pause");
}
)
