文如其名，最近在做的項目要求利用RTSP協議轉發處理完的H264視頻數據給上一層客戶端，環境是Windows的VS2013，于是就各種百度谷歌找代碼。結果在得到利用live555去做比較簡單的結論的同時也悲情地發現，網上別人貼出來的代碼基本都是Linux上面的。在修改了兩份來適用于Windows無效后，又一次陷入了百度谷歌的無盡搜索中。Anyway，最后終于解決了，所以貼出代碼跟大家分享下，希望能給和我需求相似的童鞋一點啟發，也希望有高手指正其中的問題。

用live555進行RTSP的播放基本上是通過修改其給出來的播放本地文件的DEMO來實現的。但由于其DEMO封裝的比較深，所以要直接修改他的fread處的代碼變成內存拷貝來實現實時傳輸會顯得比較別扭。本文參考了網上的一些代碼，自定義了一個繼承自H264VideoFileServerMediaSubsession的類來來進行處理，同時定義了一個繼承自FramedSource的類來做內存的拷貝操作，該類亦是區別于讀本地文件和實時流之緊要處。

代碼如下，如果覺得需要或者懶得自己搭建live555的環境亦可以在文中最后的鏈接中下載該工程（環境為VS2013），如果你的VS版本合適即可直接運行。

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)//顯示RTSP連接信息
{
 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)
{
 //設置環境
 UsageEnvironment* env;
 Boolean reuseFirstSource = False;//如果為“true”則其他接入的客戶端跟第一個客戶端看到一樣的視頻流，否則其他客戶端接入的時候將重新播放
 TaskScheduler* scheduler = BasicTaskScheduler::createNew();
 env = BasicUsageEnvironment::createNew(*scheduler);

 //創建RTSP服務器
 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\&;";

 //模擬實時流發送相關變量
 int datasize;//數據區長度
 unsigned char*  databuf;//數據區指針
 databuf = (unsigned char*)malloc(1024*1024);
 bool dosent;//rtsp發送標志位，為true則發送，否則退出

 //從文件中拷貝1M數據到內存中作為實時網絡傳輸內存模擬，如果實時網絡傳輸應該是雙線程結構，記得在這里加上線程鎖
 //此外實時傳輸的數據拷貝應該是發生在H264FramedLiveSource文件中，所以這里只是自上往下的傳指針過去給它
 FILE *pf;
 fopen_s(pf, "test.264", "rb");
 fread(databuf, 1, BUFSIZE, pf);
 datasize = BUFSIZE;
 dosent = true;
 fclose(pf);

 //上面的部分除了模擬網絡傳輸的部分外其他的基本跟live555提供的demo一樣，而下面則修改為網絡傳輸的形式，為此重寫addSubsession的第一個參數相關文件
 char const* streamName = "h264ESVideoTest";
 ServerMediaSession* sms = ServerMediaSession::createNew(*env, streamName, streamName,descriptionString);
 sms->addSubsession(H264LiveVideoServerMediaSubssion::createNew(*env, reuseFirstSource, datasize, databuf,dosent));//修改為自己實現的H264LiveVideoServerMediaSubssion
 rtspServer->addServerMediaSession(sms);

 announceStream(rtspServer, sms, streamName);//提示用戶輸入連接信息
 env->taskScheduler().doEventLoop(); //循環等待連接

 free(databuf);//釋放掉內存
 return 0;
}

自定義H264VideoFileServerMediaSubsession類

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;//數據區大小指針
 unsigned char*  Server_databuf;//數據區指針
 bool *Server_dosent;//發送標示
};
#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不是我們需要修改的文件，
                   //但是我們又要用它來初始化我們的函數，
                   //所以給個空數組進去即可
{
 Server_datasize = datasize;//數據區大小指針
 Server_databuf = databuf;//數據區指針
 Server_dosent = dosent;//發送標示
}

H264LiveVideoServerMediaSubssion::~H264LiveVideoServerMediaSubssion()
{
}

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

 //創建視頻源
 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);
}
自定義H264FramedLiveSource類

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;//數據區大小指針
 unsigned char *Framed_databuf;//數據區指針
 bool *Framed_dosent;//發送標示

 int readbufsize;//記錄已讀取數據區大小
 int bufsizel;//記錄數據區大小
};

#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;//數據區大小指針
 Framed_databuf = databuf;//數據區指針
 Framed_dosent = dosent;//發送標示
}

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);//表示延遲0秒后再執行 afterGetting 函數
 return;
}