最近被安排搞onvif，onvif的視訊傳輸，就是使用live555做伺服器，使用其提供的URL。所以live555也得去了解學習。本文簡單介紹live555的編譯，然後在原有例程上給出一個示例。

1、編譯

$ ./genMakefiles mingw 
$  export CC=gcc 
$  make  

類似地，在linux編譯方法如下：
$ ./genMakefiles linux
$ make

編譯完成後，testProgs目錄會生成很多測試程式，在不修改任何程式碼情況下，可執行這些程式進行測試。以testH264VideoStreamer為例，將H264視訊檔案放到該目錄，改名為test.264，執行testH264VideoStreamer(在mingw環境編譯得到的名稱是testH264VideoStreamer.exe)。再在VLC開啟網路串流，輸入地址rtsp://ip/testStream，如：rtsp://192.168.1.100:8554/testStream。
預設情況，該示例程式就是使用test.264檔案。如需要修改播放的檔案，則要修改原始碼檔案testH264VideoStreamer.cpp。如果需要再次編譯，直接在testProgs輸入make即可。

2、示例

/**
本程式同時提供單播、組播功能。基於testH264VideoStreamer程式修改，另參考testOnDemandRTSPServer。
注：
單播：重開VLC連線，會重新讀檔案。無馬賽克
組播：重開VLC連線，會繼續上一次的位置往下讀檔案。每次連線時，出現馬賽克，VLC出現：
      main error: pictures leaked, trying to workaround

*/
#include <liveMedia.hh>
#include <BasicUsageEnvironment.hh>
#include <GroupsockHelper.hh>

UsageEnvironment* env;
char inputFileName[128] = {0};  // 輸入的視訊檔案
H264VideoStreamFramer* videoSource;
RTPSink* videoSink;

Boolean reuseFirstSource = False;

void play(); // forward

void announceStream(RTSPServer* rtspServer, ServerMediaSession* sms,
			   char const* streamName, char const* inputFileName);

int main(int argc, char** argv) {
  strcpy(inputFileName, "test.264"); // 預設值
  if (argc == 2) {
    strcpy(inputFileName, argv[1]);
  }
  printf("Using file: %s\n", inputFileName);
  
  // Begin by setting up our usage environment:
  TaskScheduler* scheduler = BasicTaskScheduler::createNew();
  env = BasicUsageEnvironment::createNew(*scheduler);

  // 描述資訊
  char const* descriptionString
    = "Session streamed by \"testH264VideoStreamer\"";

  // RTSP伺服器，埠為8554
  RTSPServer* rtspServer = RTSPServer::createNew(*env, 8554);
  if (rtspServer == NULL) {
    *env << "Failed to create RTSP server: " << env->getResultMsg() << "\n";
    exit(1);
  }

  // 組播
  // Create 'groupsocks' for RTP and RTCP:
  struct in_addr destinationAddress;
  destinationAddress.s_addr = chooseRandomIPv4SSMAddress(*env);

  const unsigned short rtpPortNum = 18888;
  const unsigned short rtcpPortNum = rtpPortNum+1;
  const unsigned char ttl = 255;

  const Port rtpPort(rtpPortNum);
  const Port rtcpPort(rtcpPortNum);

  Groupsock rtpGroupsock(*env, destinationAddress, rtpPort, ttl);
  rtpGroupsock.multicastSendOnly(); // we're a SSM source
  Groupsock rtcpGroupsock(*env, destinationAddress, rtcpPort, ttl);
  rtcpGroupsock.multicastSendOnly(); // we're a SSM source

  // Create a 'H264 Video RTP' sink from the RTP 'groupsock':
  OutPacketBuffer::maxSize = 200000;
  videoSink = H264VideoRTPSink::createNew(*env, &rtpGroupsock, 96);

  // Create (and start) a 'RTCP instance' for this RTP sink:
  const unsigned estimatedSessionBandwidth = 500; // in kbps; for RTCP b/w share
  const unsigned maxCNAMElen = 100;
  unsigned char CNAME[maxCNAMElen+1];
  gethostname((char*)CNAME, maxCNAMElen);
  CNAME[maxCNAMElen] = '\0'; // just in case
  RTCPInstance* rtcp
  = RTCPInstance::createNew(*env, &rtcpGroupsock,
			    estimatedSessionBandwidth, CNAME,
			    videoSink, NULL /* we're a server */,
			    True /* we're a SSM source */);
  // Note: This starts RTCP running automatically

  char const* streamName = "h264ESVideoMulticast";
  ServerMediaSession* sms
    = ServerMediaSession::createNew(*env, streamName, inputFileName,
		   descriptionString, True /*SSM*/);
  sms->addSubsession(PassiveServerMediaSubsession::createNew(*videoSink, rtcp));
  rtspServer->addServerMediaSession(sms);

  announceStream(rtspServer, sms, streamName, inputFileName);

  // Start the streaming:
  *env << "Beginning streaming...\n";
  play(); // 播放

  ////////////////////////////////////////////////////////////////////////

  // 單播
  {
    char const* streamName = "h264ESVideo";
    ServerMediaSession* sms
      = ServerMediaSession::createNew(*env, streamName, streamName,
				      descriptionString);
    sms->addSubsession(H264VideoFileServerMediaSubsession
		       ::createNew(*env, inputFileName, reuseFirstSource));
    rtspServer->addServerMediaSession(sms);

    announceStream(rtspServer, sms, streamName, inputFileName);
  }

  env->taskScheduler().doEventLoop(); // does not return

  return 0; // only to prevent compiler warning
}

// 繼續讀取檔案
void afterPlaying(void* /*clientData*/) {
  *env << "...done reading from file\n";
  videoSink->stopPlaying();
  Medium::close(videoSource);
  // Note that this also closes the input file that this source read from.

  // Start playing once again:
  play();
}

void play() {
  // Open the input file as a 'byte-stream file source':
  ByteStreamFileSource* fileSource
    = ByteStreamFileSource::createNew(*env, inputFileName);
  if (fileSource == NULL) {
    *env << "Unable to open file \"" << inputFileName
         << "\" as a byte-stream file source\n";
    exit(1);
  }

  FramedSource* videoES = fileSource;

  // Create a framer for the Video Elementary Stream:
  videoSource = H264VideoStreamFramer::createNew(*env, videoES);

  // Finally, start playing:
  *env << "Beginning to read from file...\n";
  videoSink->startPlaying(*videoSource, afterPlaying, videoSink);
}

void announceStream(RTSPServer* rtspServer, ServerMediaSession* sms,
			   char const* streamName, char const* inputFileName) {
  char* url = rtspServer->rtspURL(sms);
  UsageEnvironment& env = rtspServer->envir();
  env << "\n\"" << streamName << "\" stream, from the file \""
      << inputFileName << "\"\n";
  env << "Play this stream using the URL \"" << url << "\"\n";
  delete[] url;
}