jrtplib开源库系列之二:jrtplib库example1分析说明

void checkerror(int rtperr)
{
  if (rtperr < 0)
  {
  std::cout << "ERROR: " << RTPGetErrorString(rtperr) << std::endl;
  exit(-1);
  }
}
//
// The main routine
//
int main(void)
{
#ifdef RTP_SOCKETTYPE_WINSOCK
  WSADATA dat;
  WSAStartup(MAKEWORD(2,2),&dat);
#endif // RTP_SOCKETTYPE_WINSOCK
  RTPSession sess;
  uint16_t portbase,destport;
  uint32_t destip;
  std::string ipstr;
  int status,i,num;
  std::cout << "Using version " << RTPLibraryVersion::GetVersion().GetVersionString() << std::endl;
  // First, we'll ask for the necessary information
  std::cout << "Enter local portbase:" << std::endl;
  std::cin >> portbase; //设置端口
  std::cout << std::endl;
  std::cout << "Enter the destination IP address" << std::endl;
  std::cin >> ipstr;
  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
  // ntohl
  destip = ntohl(destip);//转换为主机地址序
  std::cout << "Enter the destination port" << std::endl;
  std::cin >> destport;//设置目的地址的端口，如果测试自己给自己发送的包，请和portbase设置一致
  std::cout << std::endl;
  std::cout << "Number of packets you wish to be sent:" << std::endl;
  std::cin >> num;
  // Now, we'll create a RTP session, set the destination, send some
  // packets and poll for incoming data.
  RTPUDPv4TransmissionParams transparams;
  RTPSessionParams sessparams;
  // IMPORTANT: The local timestamp unit MUST be set, otherwise
  //            RTCP Sender Report info will be calculated wrong
  // In this case, we'll be sending 10 samples each second, so we'll
  // put the timestamp unit to (1.0/10.0)
  //在其他应用中，必须设置这个参数，比如使用RTP协议传输H264,这里必须设置为1/90000，关于如何使用RTP传输H264，请参考RFC3984协议规范
  sessparams.SetOwnTimestampUnit(1.0/10.0); 
  sessparams.SetAcceptOwnPackets(true);//注意，如果想测试自己调用自己发送的包，需要设置为true
  transparams.SetPortbase(portbase);
  status = sess.Create(sessparams,&transparams);  
  checkerror(status);
  RTPIPv4Address addr(destip,destport);
  status = sess.AddDestination(addr);
  checkerror(status);
  for(int i = 0; i < num; ++i)
  {
  // send the packet
  status = sess.SendPacket((void *)"1234567890",10,0,false,10);
       checkerror(status);
    //由于可能使用多线程，需要保证数据源数据在多线程下是安全的
    //用户在获取其他数据源发送数据之前需要调用这个接口
    //在调用完成之后需要调用EndDataAccess()接口
  sess.BeginDataAccess();
  // check incoming packets
  if (sess.GotoFirstSourceWithData()) //判断是否有其他数据源发送的数据
  {
    do
    {
    RTPPacket *pack;
    while ((pack = sess.GetNextPacket()) != NULL)
    {
      // You can examine the data here
      printf("Got packet !\n");
      // we don't longer need the packet, so
      // we'll delete it
      sess.DeletePacket(pack);
    }
    } while (sess.GotoNextSourceWithData());
  }
  sess.EndDataAccess();//由于可能使用多线程，需要保证数据源数据在多线程下是安全的
#ifndef RTP_SUPPORT_THREAD
  status = sess.Poll();
  checkerror(status);
#endif // RTP_SUPPORT_THREAD
  RTPTime::Wait(RTPTime(1,0));
  }
  sess.BYEDestroy(RTPTime(10,0),0,0);
#ifdef RTP_SOCKETTYPE_WINSOCK
  WSACleanup();
#endif // RTP_SOCKETTYPE_WINSOCK
  return 0;
}