文如其名，最近在做的项目要求利用RTSP协议转发处理完的H264视频数据给上一层客户端，环境是Windows的VS2013，于是就各种百度谷歌找代码。结果在得到利用live555去做比较简单的结论的同时也悲情地发现，网上别人贴出来的代码基本都是Linux上面的。在修改了两份来适用于Windows无效后，又一次陷入了百度谷歌的无尽搜索中。Anyway，最后终于解决了，所以贴出代码跟大家分享下，希望能给和我需求相似的童鞋一点启发，也希望有高手指正其中的问题。

用live555进行RTSP的播放基本上是通过修改其给出来的播放本地文件的DEMO来实现的。但由于其DEMO封装的比较深，所以要直接修改他的fread处的代码变成内存拷贝来实现实时传输会显得比较别扭。本文参考了网上的一些代码，自定义了一个继承自H264VideoFileServerMediaSubsession的类来来进行处理，同时定义了一个继承自FramedSource的类来做内存的拷贝操作，该类亦是区别于读本地文件和实时流之紧要处。

代码如下，如果觉得需要或者懒得自己搭建live555的环境亦可以在文中最后的链接中下载该工程（环境为VS2013），如果你的VS版本合适即可直接运行。

主文件（程序入口）

#include "H264LiveVideoServerMediaSubssion.hh"
#include "H264FramedLiveSource.hh"
#include "liveMedia.hh"
#include "BasicUsageEnvironment.hh"

#define BUFSIZE 1024*200

static void announceStream(RTSPServer* rtspServer, ServerMediaSession* sms,char const* streamName)//显示RTSP连接信息
{
 char* url = rtspServer->rtspURL(sms);
 UsageEnvironment& env = rtspServer->envir();
 env <<streamName<< "\n";
 env << "Play this stream using the URL \"" << url << "\"\n";
 delete[] url;
}

int main(int argc, char** argv)
{
 //设置环境
 UsageEnvironment* env;
 Boolean reuseFirstSource = False;//如果为“true”则其他接入的客户端跟第一个客户端看到一样的视频流，否则其他客户端接入的时候将重新播放
 TaskScheduler* scheduler = BasicTaskScheduler::createNew();
 env = BasicUsageEnvironment::createNew(*scheduler);

 //创建RTSP服务器
 UserAuthenticationDatabase* authDB = NULL;
 RTSPServer* rtspServer = RTSPServer::createNew(*env, 8554, authDB);
 if (rtspServer == NULL) {
  *env << "Failed to create RTSP server: " << env->getResultMsg() << "\n";
  exit(1);
 }
 char const* descriptionString= "Session streamed by \"testOnDemandRTSPServer\"";

 //模拟实时流发送相关变量
 int datasize;//数据区长度
 unsigned char*  databuf;//数据区指针
 databuf = (unsigned char*)malloc(1024*1024);
 bool dosent;//rtsp发送标志位，为true则发送，否则退出

 //从文件中拷贝1M数据到内存中作为实时网络传输内存模拟，如果实时网络传输应该是双线程结构，记得在这里加上线程锁
 //此外实时传输的数据拷贝应该是发生在H264FramedLiveSource文件中，所以这里只是自上往下的传指针过去给它
 FILE *pf;
 fopen_s(&pf, "test.264", "rb");
 fread(databuf, 1, BUFSIZE, pf);
 datasize = BUFSIZE;
 dosent = true;
 fclose(pf);

 //上面的部分除了模拟网络传输的部分外其他的基本跟live555提供的demo一样，而下面则修改为网络传输的形式，为此重写addSubsession的第一个参数相关文件
 char const* streamName = "h264ESVideoTest";
 ServerMediaSession* sms = ServerMediaSession::createNew(*env, streamName, streamName,descriptionString);
 sms->addSubsession(H264LiveVideoServerMediaSubssion::createNew(*env, reuseFirstSource, &datasize, databuf,&dosent));//修改为自己实现的H264LiveVideoServerMediaSubssion
 rtspServer->addServerMediaSession(sms);

 announceStream(rtspServer, sms, streamName);//提示用户输入连接信息
 env->taskScheduler().doEventLoop(); //循环等待连接

 free(databuf);//释放掉内存
 return 0;
}

自定义H264VideoFileServerMediaSubsession类

H264VideoFileServerMediaSubsession.hh

#ifndef _H264_LIVE_VIDEO_SERVER_MEDIA_SUBSESSION_HH
#define _H264_LIVE_VIDEO_SERVER_MEDIA_SUBSESSION_HH
#include "H264VideoFileServerMediaSubsession.hh"

class H264LiveVideoServerMediaSubssion : public H264VideoFileServerMediaSubsession {

public:
 static H264LiveVideoServerMediaSubssion* createNew(UsageEnvironment& env, Boolean reuseFirstSource, int *datasize, unsigned char*  databuf, bool *dosent);

protected: // we're a virtual base class
 H264LiveVideoServerMediaSubssion(UsageEnvironment& env, Boolean reuseFirstSource, int *datasize, unsigned char*  databuf, bool *dosent);
 ~H264LiveVideoServerMediaSubssion();

protected: // redefined virtual functions
 FramedSource* createNewStreamSource(unsigned clientSessionId,unsigned& estBitrate);
public:
 char fFileName[100];

 int *Server_datasize;//数据区大小指针
 unsigned char*  Server_databuf;//数据区指针
 bool *Server_dosent;//发送标示
};
#endifH264VideoFileServerMediaSubsession.cpp

#include "H264LiveVideoServerMediaSubssion.hh"
#include "H264FramedLiveSource.hh"
#include "H264VideoStreamFramer.hh"

H264LiveVideoServerMediaSubssion* H264LiveVideoServerMediaSubssion::createNew(UsageEnvironment& env, Boolean reuseFirstSource, int *datasize, unsigned char*  databuf, bool *dosent)
{
 return new H264LiveVideoServerMediaSubssion(env, reuseFirstSource, datasize, databuf, dosent);
}

H264LiveVideoServerMediaSubssion::H264LiveVideoServerMediaSubssion(UsageEnvironment& env, Boolean reuseFirstSource, int *datasize, unsigned char*  databuf, bool *dosent)
: H264VideoFileServerMediaSubsession(env, fFileName, reuseFirstSource)//H264VideoFileServerMediaSubsession不是我们需要修改的文件，
                   //但是我们又要用它来初始化我们的函数，
                   //所以给个空数组进去即可
{
 Server_datasize = datasize;//数据区大小指针
 Server_databuf = databuf;//数据区指针
 Server_dosent = dosent;//发送标示
}

H264LiveVideoServerMediaSubssion::~H264LiveVideoServerMediaSubssion()
{
}

FramedSource* H264LiveVideoServerMediaSubssion::createNewStreamSource(unsigned clientSessionId, unsigned& estBitrate)
{
 /* Remain to do : assign estBitrate */
 estBitrate = 1000; // kbps, estimate

 //创建视频源
 H264FramedLiveSource* liveSource = H264FramedLiveSource::createNew(envir(), Server_datasize, Server_databuf, Server_dosent);
 if (liveSource == NULL)
 {
  return NULL;
 }

 // Create a framer for the Video Elementary Stream:
 return H264VideoStreamFramer::createNew(envir(), liveSource);
}
自定义H264FramedLiveSource类

H264FramedLiveSource.hh

#ifndef _H264FRAMEDLIVESOURCE_HH
#define _H264FRAMEDLIVESOURCE_HH

#include <FramedSource.hh>

class H264FramedLiveSource : public FramedSource
{
public:
 static H264FramedLiveSource* createNew(UsageEnvironment& env, int *datasize, unsigned char*  databuf, bool *dosent, unsigned preferredFrameSize = 0, unsigned playTimePerFrame = 0);

protected:
 H264FramedLiveSource(UsageEnvironment& env, int *datasize, unsigned char*  databuf, bool *dosent, unsigned preferredFrameSize, unsigned playTimePerFrame);
 ~H264FramedLiveSource();

private:
 virtual void doGetNextFrame();
 int TransportData(unsigned char* to, unsigned maxSize);

protected:
 int *Framed_datasize;//数据区大小指针
 unsigned char *Framed_databuf;//数据区指针
 bool *Framed_dosent;//发送标示

 int readbufsize;//记录已读取数据区大小
 int bufsizel;//记录数据区大小
};

#endifH264FramedLiveSource.cpp

#include "H264FramedLiveSource.hh"

H264FramedLiveSource::H264FramedLiveSource(UsageEnvironment& env, int *datasize, unsigned char*  databuf, bool *dosent, unsigned preferredFrameSize, unsigned playTimePerFrame)
: FramedSource(env)
{
 Framed_datasize = datasize;//数据区大小指针
 Framed_databuf = databuf;//数据区指针
 Framed_dosent = dosent;//发送标示
}

H264FramedLiveSource* H264FramedLiveSource::createNew(UsageEnvironment& env, int *datasize, unsigned char*  databuf, bool *dosent, unsigned preferredFrameSize, unsigned playTimePerFrame)
{
 H264FramedLiveSource* newSource = new H264FramedLiveSource(env, datasize, databuf, dosent, preferredFrameSize, playTimePerFrame);
 return newSource;
}

H264FramedLiveSource::~H264FramedLiveSource()
{
}

void H264FramedLiveSource::doGetNextFrame()
{
 if (*Framed_dosent == true)
 {
  *Framed_dosent = false;
  bufsizel = *Framed_datasize;
  readbufsize = 0;

  fFrameSize = fMaxSize;
  memcpy(fTo, Framed_databuf + readbufsize, fFrameSize);
  readbufsize += fFrameSize;
 }
 else
 {
  if (bufsizel - readbufsize>fMaxSize)
  {
   fFrameSize = fMaxSize;
   memcpy(fTo, Framed_databuf + readbufsize, fFrameSize);
   readbufsize += fFrameSize;
  }
  else
  {
   memcpy(fTo, Framed_databuf + readbufsize, bufsizel - readbufsize);
   *Framed_dosent = true;
  }
 }

 nextTask() = envir().taskScheduler().scheduleDelayedTask(0,(TaskFunc*)FramedSource::afterGetting, this);//表示延迟0秒后再执行 afterGetting 函数
 return;
}