jrtplib使用筆記

一、簡述

RTP 是目前解決流媒體實時傳輸問題的最好辦法，而JRTPLIB 是一個用C++語言實現的RTP庫，包括UDP通訊。剛使用JRTPLIB，對JRTPLIB的理解還不夠深，當做使用時，積累的一些經驗寫個筆記吧。

二、RTP協議

實時傳送協議（Real-time Transport Protocol或簡寫RTP，也可以寫成RTTP）是一個網絡傳輸協議，RTP協議詳細說明了在互聯網上傳遞音頻和視頻的標準數據包格式。它一開始被設計爲一個多播協議，但後來被用在很多單播應用中。RTP協議常用於流媒體系統（配合RTCP協議或者RTSP協議）。因爲RTP自身具有Time stamp所以在ffmpeg 中被用做一種formate。

RTP協議的詳細介紹，請參考這篇文章http://www.360doc.com/content/11/1009/15/496343_154624612.shtml

三、RTPSession類

這裏不介紹jrtplib的編譯安裝，這個很簡單，網上很多地方都有講解。

jrtplib的使用中，主要是圍繞這個類來實現的，因此大家有必要去查看源碼，看這類的實現。爲了方便使用，我在這做了RTPSession的繼承封裝，下面直接貼代碼了。

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應用需鏈接的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轉成字符串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轉成整形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);//必須設置
		transparams.SetPortbase(port);//port必須是偶數
		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包就會觸發
	void RTPSessionUtils::OnRTPPacket(RTPPacket *pack,const RTPTime &receivetime,
		const RTPAddress *senderaddress)
	{
		std::cout << "OnRTPPacket: data:" << pack->GetPayloadData() << std::endl;
	}

	//收到rtcp包觸發
	void RTPSessionUtils::OnRTCPCompoundPacket(RTCPCompoundPacket *pack,const RTPTime &receivetime,
		const RTPAddress *senderaddress)
	{
		std::cout << "OnRTCPCompoundPacket: data:" << pack->GetCompoundPacketData() << std::endl;
	}

	//隔段時間就會觸發,也可以用於收包回調函數
	//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");
}