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  • jrtplib的使用

    JRTPLIB库的使用
    文档:
    http://research.edm.uhasselt.be/jori/jrtplib/documentation/index.html
    一些介绍:
    http://doserver.net/read.php?1028
    http://doserver.net/read.php/1027.htm
    http://doserver.net/read.php/1685.htm
    如今開始对几个example分析一下,只是,就没有文档吗?
    这里,具体的解释了几个样例:
    http://hi.baidu.com/hanyuejun2006/blog/item/8a8ed939a9e344f53b87ce23.html
    这里算一个:
    http://xiyong8260.blog.163.com/blog/static/665146212008824112748499/
    重要的是里面还讲了一些嵌入式方面的内容。
    收和发的样例:
    http://blog.chinaunix.net/u2/61880/showart_728528.html
    比較具体的系列文章:http://www.cnitblog.com/tinnal/archive/2009/01/01/53342.html

    PS:关于POLL的问题,发现仅仅有调用者这个函数的时候,才会查询是否有包发过来,才会接收包。
    If you're not using the poll thread, this function must be called regularly to process incoming data and to send RTCP data when necessary.

    关于例程能够分为下面几个部分:


    (一)BASIC USAGE:
    1)SET PARAMS
        关于会话的參数
    2)SET TRANSPARAMS
        关于传输层的參数
    3)CREATE SESSION
        创建会话
    4)SET PACKET ATTRIBUTES
        包的属性设置
    5)ADD DESTINATION
        加入�目的地址 
    6)PREPARE DATA
        准备数据
    7)SEND PACKET
        发送包
    8)DATAACCESS
        数据处理(锁定操作,是指此时POLL线程不能改变正在处理的数据)
    9)BYE
        退出会话
    example:
    #include "rtpsession.h"
    #include "rtppacket.h"
    #include "rtpudpv4transmitter.h"
    #include "rtpsessionparams.h"
    #include "rtperrors.h"
    #include "rtpipv4address.h"
    #include <netinet/in.h>
    #include <arpa/inet.h>
    #include <stdio.h>
    #include <stdlib.h>
    #include <iostream>
    #include <string>

    void checkerror(int rtperr)
    {
        if(rtperr < 0)
        {
            std::cout<<"ERROR:"<<RTPGetErrorString(rtperr)<<std::endl;
            exit(-1);
        }
    }

    int main()
    {
        RTPSession sess;
        uint16_t portbase;
        int status;

        //set params


        RTPSessionParams sessparams;
        sessparams.SetOwnTimestampUnit(1.0/10.0);
        sessparams.SetAcceptOwnPackets(true);

        //set transparams


        RTPUDPv4TransmissionParams transparams;
        transparams.SetPortbase(8000);

        //create a session


        status = sess.Create(sessparams, &transparams);
        checkerror(status);

        //set default packet attributes


        sess.SetDefaultPayloadType(0);
        sess.SetDefaultMark(false);
        sess.SetDefaultTimestampIncrement(10);

        //destination address


        uint16_t destport;
        uint32_t destip;
        std::string ipstr;
        std::cout<<"Enter the IP: "<<std::endl;
        std::cin>>ipstr;
        destip = inet_addr(ipstr.c_str());
        if(destip == INADDR_NONE)
        {
            std::cerr<<"Bad IP"<<std::endl;
            exit(-1);
        }
        destip = ntohl(destip);
        //uint8_t localip[] = {192, 168, 0, 3};


        RTPIPv4Address addr(destip, 8000);

        //add destination


        status = sess.AddDestination(addr);
        checkerror(status);

        //prepare payload data


        uint8_t silencebuffer[160];
        for(int i = 0; i < 160; i++)
        {
            silencebuffer[i] = 128;
        }

        //for time checking


        RTPTime delay(0.020);
        RTPTime starttime = RTPTime::CurrentTime();

        bool done = false;
        sess.Poll();


        while(!done)
        {
            status = sess.SendPacket(silencebuffer, 160);
            checkerror(status);

            //receive data


            sess.BeginDataAccess();
            if(sess.GotoFirstSource())
            {
                do
                {
                    RTPPacket *pack;
                    while((pack = sess.GetNextPacket()) != NULL)
                    {
                        std::cout<<"Got packet!"<<std::endl;
                        std::cout<<"sequence number: "<<pack->GetSequenceNumber()<<std::endl;
                        std::cout<<"Extended SN: "<<pack->GetExtendedSequenceNumber()<<std::endl;
                        std::cout<<"SSRC: "<<pack->GetSSRC()<<std::endl;
                        std::cout<<"Data: "<<pack->GetPayloadData()<<std::endl;
                        sess.DeletePacket(pack);
                    }
                }while(sess.GotoNextSource());
            }
            sess.EndDataAccess();
            
            RTPTime::Wait(delay);
        
            RTPTime t = RTPTime::CurrentTime();
            t -= starttime;
            if(> RTPTime(6, 0))
            {
                done = true;
            }
        }
        
        delay = RTPTime(10.0);
        sess.BYEDestroy(delay, "Time's up", 9);
        return(0);
    }



    (二)Your Own Session:
    能够继承session创建MySession加入�自己定制的处理, 这些处理是由session的protected methods 定义的。參考文档能够确定要定制的处理。

    example:

    #include "rtpsession.h"
    #include "rtppacket.h"
    #include "rtpudpv4transmitter.h"
    #include "rtpipv4address.h"
    #include "rtpsessionparams.h"
    #include "rtperrors.h"
    #include "rtpsourcedata.h"
    #include <stdlib.h>
    #include <stdio.h>
    #include <iostream>
    #include <string>

    class MyRTPSession : public RTPSession
    {
        protected:

    //what to do on new source?
            void OnNewSource(RTPSourceData *dat)
            {
                if(dat->IsOwnSSRC())
                {
                    return;
                }
                uint32_t ip;
                uint16_t port;
                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;
                }
                else
                {
                    return;
                }
                RTPIPv4Address dest(ip, port);
                AddDestination(dest);

                struct in_addr inaddr;
                inaddr.s_addr = htonl(ip);
                std::cout<<"Adding destination"<<std::string(inet_ntoa(inaddr))
                    <<":"<<port<<std::endl;
            }
    //what to do on byepacket?
            void OnBYEPacket(RTPSourceData *dat)
            {
                std::cout<<"OnBYEPacket"<<std::endl;
                if(dat->IsOwnSSRC())
                {
                    return;
                }
                uint32_t ip;
                uint16_t port;
                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;
                }
                else
                {
                    return;
                }
                RTPIPv4Address dest(ip, port);
                DeleteDestination(dest);
                
                struct in_addr inaddr;
                inaddr.s_addr = htonl(ip);
                std::cout<<"Deleting destination"
                    <<std::string(inet_ntoa(inaddr))
                    <<":"<<port<<std::endl;
            }
    //what to do on remove source?
            void OnRemoveSource(RTPSourceData *dat)
            {
                std::cout<<"OnRemoveSource"<<std::endl;
                if(dat->IsOwnSSRC())
                {
                    return;
                }
                if(dat->ReceivedBYE())
                {
                    return;
                }
                uint32_t ip;
                uint16_t port;
                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;
                }
                else
                {
                    return;
                }
                RTPIPv4Address dest(ip, port);
                DeleteDestination(dest);
                
                struct in_addr inaddr;
                inaddr.s_addr = htonl(ip);
                std::cout<<"Deleting destination"
                    <<std::string(inet_ntoa(inaddr))
                    <<":"<<port<<std::endl;
            }
    };



    (三)Important Classes:
    分析參数:RTPSourceData-HOW TO KNOW RTCP?
    从(二)中,你可能已经了解到了On...等定义了session在收发包时的动作,而为了分析这些包的參数,你须要的是RTPSourceData这个參数。Source指的是一个会话的參与者,在本地保存了一个參与者列表,和与之相关的信息。这些信息是从该源发送的RTCP信息提取的。
    为了便于和理论分析比較,如今将5中RTCP分组报告和它们的实现列出:
    指的注意的是:据我眼下的理解是,本地维护一个源的列表,而这些RTCP分组,并没有它们的实体,而是得到这些分组后就分析为和一个源描写叙述符,即RTPSource关联的数据。应该是遍历这个源列表,而获得它们的信息。而怎样遍历的问题,稍后讨论。


    发送者报告(SR)

    V| P| RC| PT=SR=200| LEN|


    发送者SSRC (已关联)

     


    NTP时间戳(高32位) SR_GetNTPTimestamp ()

    NTP时间戳(低32位)

     


    RTP时间戳 SR_GetRTPTimestamp () 

     


    发送者分组计数器 SR_GetPacketCount()

     


    发送者字节计数器 SR_GetByteCount ()

     


    ...(以下是这个发送者所发送的接收者报告,在以下和RR一起讨论)

    附加信息:

    这个源是否有发送发送者报告

    SR_HasInfo ()

    这个发送者报告接收的时间

    SR_GetReceiveTime ()

    以及以SR_Prev_开头的,获得倒数第二个发送者报告的信息。



    接收者报告(RR)

    V| P| RC| PT=SR=201| LEN|

     


    SSRC1(第一个接收者报告块所关联的发送者) (已关联)

    分组丢失率 | 丢失分组总数|

    扩展的最高序号

    间隔抖动

    最新的发送者报告时间戳(LSR)

    SR最新间隔(DLSR)

    附加信息:
    这个源是否有发送接收者报告
    接收者报告接收时间
    以及以RR_Prev_开头的,获得倒数第二个接收者报告的信息。


    源描叙分组(SDES)

    V| P| RC| PT=SR=202| LEN|

     


    SSRC/CSRC1 (已关联)

     


    SDES项

    由SDES_Get...等描写叙述

    能够推断的是存在一种机制,能够在本地定制自己要发送的SDES包括的信息。



    BYE分组(BYE)

    V| P| RC| PT=SR=202| LEN|


    SSRC/CSRC (已关联)


    原因长度| 退出会话原因
    GetBYEReason (size_t *len)

     

    附加信息(见文档)

     



    依据以上的信息,大概知道了怎样获取一个源的信息;问题是怎样遍历这个源列表来处理一个源?
    其实,在大多数的样例里,使用的类仅仅是RTPSession,通过这个类能够管理会话的大部分细节。
    管理会话:RTPSession-MANAGE A SESSION
    对一次会话的管理,大概有下面几方面:
    *创建会话
    *退出会话
    *管理目的地址(加入�,忽略)
    *发送和接收数据包(用户仅仅须要关心RTP包),另外,APP包也是由用户负责的
    *时间戳设定
    *管理SDES信息项
    *管理源列表
    *管理广播组
    ...
    一般来说,使用一个类都是使用它的public接口,可是你能够像(二)描写叙述的那样,通过继承来定制自己的一些行为。On...
    着重讲的是管理源列表。
    bool  GotoFirstSource ()
      Starts the iteration over the participants by going to the first member in the table.
    bool  GotoNextSource ()
      Sets the current source to be the next source in the table.
    bool  GotoPreviousSource ()
      Sets the current source to be the previous source in the table.
    bool  GotoFirstSourceWithData ()
      Sets the current source to be the first source in the table which has RTPPacket instances that we haven't extracted yet.
    bool  GotoNextSourceWithData ()
      Sets the current source to be the next source in the table which has RTPPacket instances that we haven't extracted yet.
    bool  GotoPreviousSourceWithData ()
      Sets the current source to be the previous source in the table which has RTPPacket instances that we haven't extracted yet.
    RTPSourceData GetCurrentSourceInfo ()
      Returns the RTPSourceData instance for the currently selected participant.
    RTPSourceData GetSourceInfo (uint32_t ssrc)
      Returns the RTPSourceData instance for the participant identified by ssrc, or NULL if no such entry exists. 
    bool  GotEntry (uint32_t ssrc)
      Returns true if an entry for participant ssrc exists and false otherwise.
    RTPSourceData GetOwnSourceInfo ()
      If present, it returns the RTPSourceData instance of the entry which was created by CreateOwnSSRC. 


    迭代的例程:

    非常明显,这是C++风格,使用了迭代器的抽象。而GetCurrentSourceInfo ()和GetSourceInfo (uint32_t ssrc)的返回类型-RTPSourceData能够使我们得以获取源列表的RTCP信息。
    使用这样的迭代的例程:
     sess.BeginDataAccess();
            if(sess.GotoFirstSource())
            {
                do
                {
                    RTPPacket *pack;
                    while((pack = sess.GetNextPacket()) != NULL)
                    {
                //deal with the packet
                        sess.DeletePacket(pack);
                    }
                }while(sess.GotoNextSource());
            }
    sess.EndDataAccess();
    以上,我们能够获得訪问源的信息的机制。

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  • 原文地址:https://www.cnblogs.com/blfshiye/p/3780267.html
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