linux下的实时流媒体编程.html

基于Linux的实时流媒体编程介绍以及实现

    char* errstr = RTPGetErrorString(err);
    printf("Error:%s\\n", errstr);
    exit(-1);
  }
}

int main(int argc, char** argv)
{
  RTPSession sess;
  unsigned long destip;
  int destport;
  int portbase = 6000;
  int status, index;
  char buffer[128];

  if (argc != 3) {
    printf("Usage: ./sender destip destport\\n");
    return -1;
  }

  // 获得接收端的IP地址和端口号
  destip = inet_addr(argv[1]);
  if (destip == INADDR_NONE) {
    printf("Bad IP address specified.\\n");
    return -1;
  }
  destip = ntohl(destip);
  destport = atoi(argv[2]);

  // 创建RTP会话
  status = sess.Create(portbase);
  checkerror(status);

  // 指定RTP数据接收端
  status = sess.AddDestination(destip, destport);
  checkerror(status);

  // 设置RTP会话默认参数
  sess.SetDefaultPayloadType(0);
  sess.SetDefaultMark(false);
  sess.SetDefaultTimeStampIncrement(10);

  // 发送流媒体数据
  index = 1;
  do {
    sprintf(buffer, "%d: RTP packet", index ++);
    sess.SendPacket(buffer, strlen(buffer));
    printf("Send packet !\\n");
  } while(1);

  return 0;
}
</code></pre></td></tr></tbody></table>



<p>清单4则给出了数据接收端的完整代码，它负责从指定的端口不断地读取RTP数据包：</p>

<p>代码清单4：receiver.cpp</p>



<table bgcolor="#cccccc" border="1" cellpadding="5" cellspacing="0" width="100%">
<tbody><tr><td><pre><code>

#include &lt;stdio.h&gt;
#include "rtpsession.h"
#include "rtppacket.h"

// 错误处理函数
void checkerror(int err)
{
  if (err &lt; 0) {
    char* errstr = RTPGetErrorString(err);
    printf("Error:%s\\n", errstr);
    exit(-1);
  }
}

int main(int argc, char** argv)
{
  RTPSession sess;
  int localport;
  int status;

  if (argc != 2) {
    printf("Usage: ./sender localport\\n");
    return -1;
  }

   // 获得用户指定的端口号
  localport = atoi(argv[1]);

  // 创建RTP会话
  status = sess.Create(localport);
  checkerror(status);

  do {
    // 接受RTP数据
    status = sess.PollData();
	// 检索RTP数据源
    if (sess.GotoFirstSourceWithData()) {
      do {
        RTPPacket* packet;
        // 获取RTP数据报
        while ((packet = sess.GetNextPacket()) != NULL) {
          printf("Got packet !\\n");
          // 删除RTP数据报
          delete packet;
        }
      } while (sess.GotoNextSourceWithData());
    }
  } while(1);

  return 0;
}
</code></pre></td></tr></tbody></table>

<p>本文源码<a href="http://www-900.ibm.com/developerWorks/cn/linux/l-mdst/code.zip">下载</a>  </p>
<p><a name="3"><span class="atitle2">四、小结</span></a></p><p>随着多媒体数据在
Internet上所承担的作用变得越来越重要，需要实时传输音频和视频等多媒体数据的场合也将变得越来越多，如IP电话、视频点播、在线会议等。RTP
是用来在Internet上进行实时流媒体传输的一种协议，目前已经被广泛地应用在各种场合，JRTPLIB是一个面向对象的RTP封装库，利用它可以很
方便地完成Linux平台上的实时流媒体编程。</p>

<p><a name="4"><span class="atitle2">五、参考资源</span></a></p><p>1. 在JRTPLIB的网站http://lumumba.luc.ac.be/jori/jrtplib/jrtplib.html上，可以下载到JRTPLIB最新的源码包，并且还能找到一些与RTP相关的资源。</p>
<p>2. 顾淑珍等编著，宽带增值服务开发实例，北京：机械工业出版社，2002</p>
<p>3. 黄永峰等编著，IP网络多媒体通信技术，北京：人民邮电出版社，2003</p>








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