live555 client 接收rtp数据

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2014-03-08  22:05:58  技术分享

描述live555 client即openRTSP的流程，简单点说，playCommon.cpp，流为h264和g726。在实际项目中已成功应用。

以下为我所见所得，有错误之处请指正，谢谢！

1、live555的三种任务

socket handler,event handler,delay task。

这三种任务的特点是，前两个加入执行队列后会一直存在，而delay task在执行完一次后会立即弃掉。

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/*** socket handler ***/
 
//定义
 
// For handling socket operations in the background (from the event loop):
 
typedef void BackgroundHandlerProc(void* clientData, int mask);
 
//注册
void BasicTaskScheduler
 
  ::setBackgroundHandling(int socketNum, int conditionSet, BackgroundHandlerProc* handlerProc, void* clientData) {}
 
//执行
BasicTaskScheduler::SingleStep(unsigned maxDelayTime)
{
 
  (*handler->handlerProc)(handler->clientData, resultConditionSet);
 
}
 
 
/*** event handler ***/
 
//定义
typedef void TaskFunc(void* clientData);
 
//注册
EventTriggerId EventTriggerId BasicTaskScheduler0
 
::createEventTrigger(TaskFunc* eventHandlerProc) {}
 
//执行
BasicTaskScheduler::SingleStep(unsigned maxDelayTime)
{
 
    (*fTriggeredEventHandlers[i])(fTriggeredEventClientDatas[i]);
 
}
 
 
/*** delay task ***/
 
//定义
 
typedef void TaskFunc(void* clientData);//跟event handler一样。
 
//注册
 
TaskToken BasicTaskScheduler0::
 
scheduleDelayedTask(int64_t microseconds,TaskFunc* proc, void* clientData) {}
 
//执行
BasicTaskScheduler::SingleStep(unsigned maxDelayTime)
{
 
  fDelayQueue.handleAlarm();
 
}
 
 
void DelayQueue::handleAlarm()
{
    if (head()->fDeltaTimeRemaining != DELAY_ZERO) synchronize();
 
    if (head()->fDeltaTimeRemaining == DELAY_ZERO)
    {
        // This event is due to be handled:
        DelayQueueEntry* toRemove = head();
 
        removeEntry(toRemove); // do this first, in case handler accesses queue
 
        toRemove->handleTimeout();   //仅执行一次后就remove
    }
}
2、rtsp交互
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//OPTIONS--->DESCRIBE--->SETUP--->PLAY，这是最通用的交互了。
 
getOptions()--->continueAfterOPTIONS()--->
 
getSDPDescription()--->continueAfterDESCRIBE()
{
 
    session = MediaSession::createNew(*env, sdpDescription);
 
    while()
    {
        //音视频子会话
        subsession->initiate();
    }
    setupStreams();
}
 
--->
 
//setupStreams为递归函数(setupStreams-->continueAfterSETUP-->setupStreams)
//setupSubsession所有的子会话
setupStreams()
{
    while()
    {
        setupSubsession(subsession, streamUsingTCP, forceMulticastOnUnspecified, continueAfterSETUP);
    }
    startPlayingSession(session, initialSeekTime, endTime, scale, continueAfterPLAY);
}

3、以getOptions举例

getOptions(continueAfterOPTIONS)，getOptions后怎么调用到continueAfterOPTIONS的，如下:

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//responseHandler* afterFunc 都由handler() 执行
getOptions(continueAfterOPTIONS)--->sendOptionsCommand()--->sendRequest()
{
--->openConnection()
{
    --->connectToServer()
    {
        setBackgroundHandling(,SOCKET_WRITABLE|SOCKET_EXCEPTION,connectionHandler,);
    }
 
    //连接server ok
    {
        setBackgroundHandling(,SOCKET_READABLE|SOCKET_EXCEPTION,incomingDataHandler,);
    }
}
 
if (connectionIsPending) {
      fRequestsAwaitingConnection.enqueue(request);
      return request->cseq();
    }
 
}
--->doEventLoop--->SingleStep()
{
    //socket状态符合，就执行注册好的函数，例如connectionHandler/incomingDataHandler等
    (*handler->handlerProc)(handler->clientData, resultConditionSet);
}
SingleStep()    //1th step,执行connectionHandler,SOCKET_WRITABLE
{
    handler->handlerProc = connectionHandler;
}
SingleStep()    //2th step,执行incomingDataHandler,SOCKET_READABLE
{
    handler->handlerProc = incomingDataHandler;
}
 
//incomingDataHandler会调用到continueAfterOPTIONS
void RTSPClient::incomingDataHandler(void* instance, int /*mask*/) {
  RTSPClient* client = (RTSPClient*)instance;
  client->incomingDataHandler1();
}
 
void RTSPClient::incomingDataHandler1() {
  struct sockaddr_in dummy; // ‘from‘ address - not used
 
  int bytesRead = readSocket(envir(), fInputSocketNum, (unsigned char*)&fResponseBuffer[fResponseBytesAlreadySeen], fResponseBufferBytesLeft, dummy);
  handleResponseBytes(bytesRead)
  {
    //call continueAfterOPTIONS() ,etc.
    (*foundRequest->handler())(this, resultCode, resultString);
  }
}

4、client get rtp_packet

●  先从setupStreams先入手吧

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void setupStreams()
{
    createOutputFiles()
    {
        while ((subsession = iter.next()) != NULL)
        {
            //h264
            fileSink = H264VideoFileSink::createNew(*env, outFileName,
                                subsession->fmtp_spropparametersets(),
                                fileSinkBufferSize, oneFilePerFrame);
 
            //g726
            // Normal case:
            fileSink = FileSink::createNew(*env, outFileName,
                               fileSinkBufferSize, oneFilePerFrame);
             
            subsession->sink->startPlaying(*(subsession->readSource()),
                               subsessionAfterPlaying,
                               subsession);
        }
    }
}
//------->
Boolean MediaSink::startPlaying(MediaSource& source,
                afterPlayingFunc* afterFunc,
                void* afterClientData)
{ 
  fSource = (FramedSource*)&source;
 
  fAfterFunc = afterFunc;
  fAfterClientData = afterClientData;
  return continuePlaying(); 
}
//------->
Boolean FileSink::continuePlaying()
{
  if (fSource == NULL) return False;
 
  fSource->getNextFrame(fBuffer, fBufferSize,
            afterGettingFrame, this,
            onSourceClosure, this);
 
  return True;
}

●  再从FileSink::continuePlaying入手

FileSink::continuePlaying()

FramedSource::getNextFrame()

MultiFramedRTPSource::doGetNextFrame()

MultiFramedRTPSource::doGetNextFrame1()

//以下::仅表示static func声明所在的类

static void FramedSource::afterGetting(FramedSource* source);

static void FileSink::afterGettingFrame(void* clientData, unsigned frameSize,unsigned numTruncatedBytes,

                                                              struct timeval presentationTime,unsigned durationInMicroseconds);

  • MultiFramedRTPSource::doGetNextFrame1()

是递归函数，退出条件为

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while (fNeedDelivery) //正常测试接收时，fNeedDelivery == 1
{
    if (nextPacket == NULL)
    {
       break;
    }
}


(Enter->Exit)：即时

(Enter,) ：和最近的(,Exit)配对

(,Exit)：和最近的(Enter,)配对

static afterGetting::nth(Enter,) <--->static afterGetting::n+1th(,Exit)

从第一次调用continuePlaying()跟踪。可以直接跳到3th。

4.1 step1th

continuePlaying()--->getNextFrame()--->doGetNextFrame()--->

doGetNextFrame1(Enter->Exit[nextPacket == NULL])--->......自己可以trace--->

startPlayingSession()--->setupStreams()--->SingleStep()::1th--->

networkReadHandler1(Enter,)--->doGetNextFrame1(Enter,)--->

static afterGetting(Enter,)--->static afterGettingFrame(Enter,)--->H264or5VideoFileSink::afterGettingFrame()-->

File








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