jrtplib使用笔记[通俗易懂]

大家好，又见面了，我是你们的朋友全栈君。

一、简述

RTP 是目前解决流媒体实时传输问题的最好办法，而JRTPLIB 是一个用C++语言实现的RTP库，包括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，也可以写成RTTP）是一个网络传输协议，RTP协议详细说明了在互联网上传递音频和视频的标准数据包格式。它一开始被设计为一个多播协议，但后来被用在很多单播应用中。RTP协议常用于流媒体系统（配合RTCP协议或者RTSP协议）。因为RTP自身具有Time stamp所以在ffmpeg 中被用做一种formate。

RTP协议的详细介绍，请参考这篇文章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，这个很简单，网上很多地方都有讲解。

jrtplib的使用中，主要是围绕这个类来实现的，因此大家有必要去查看源码，看这类的实现。为了方便使用，我在这做了RTPSession的继承封装，下面直接贴代码了。

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 WIN32
		WSADATA dat;
		WSAStartup(MAKEWORD(2,2),&dat);
#endif // WIN32
	}

	RTPSessionUtils::~RTPSessionUtils()
	{
#ifdef WIN32
		WSACleanup();
#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;
	}

	//只要有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,也可以用于收包回调函数
	//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");
}

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