live555 client 接收rtp資料

2014-03-08 22:05:58

描述live555 client即openRTSP的流程，簡單點說，playCommon.cpp，流為h264和g726。在實際項目中已成功應用。

以下為我所見所得，有錯誤之處請指正，謝謝！

1、live555的三種任務

socket handler,event handler,delay task。

這三種任務的特點是，前兩個加入執行隊列後會一直存在，而delay task在執行完一次後會立即棄掉。

/*** socket handler ***/
 
//定義
 
// For handling socket operations in the background (from the event loop):
 
typedef void BackgroundHandlerProc(void* clientData, int mask);
 
//注冊
void BasicTaskScheduler
 
  ::setBackgroundHandling(int socketNum, int conditionSet, BackgroundHandlerProc* handlerProc, void* clientData) {}
 
//執行
BasicTaskScheduler::SingleStep(unsigned maxDelayTime)
{
 
  (*handler->handlerProc)(handler->clientData, resultConditionSet);
 
}
 
 
/*** event handler ***/
 
//定義
typedef void TaskFunc(void* clientData);
 
//注冊
EventTriggerId EventTriggerId BasicTaskScheduler0
 
::createEventTrigger(TaskFunc* eventHandlerProc) {}
 
//執行
BasicTaskScheduler::SingleStep(unsigned maxDelayTime)
{
 
    (*fTriggeredEventHandlers[i])(fTriggeredEventClientDatas[i]);
 
}
 
 
/*** delay task ***/
 
//定義
 
typedef void TaskFunc(void* clientData);//跟event handler一樣。
 
//注冊
 
TaskToken BasicTaskScheduler0::
 
scheduleDelayedTask(int64_t microseconds,TaskFunc* proc, void* clientData) {}
 
//執行
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();   //僅執行一次後就remove
    }
}

2、rtsp互動

//OPTIONS--->DESCRIBE--->SETUP--->PLAY，這是最通用的互動了。
 
getOptions()--->continueAfterOPTIONS()--->
 
getSDPDescription()--->continueAfterDESCRIBE()
{
 
    session = MediaSession::createNew(*env, sdpDescription);
 
    while()
    {
        //音視訊子會話
        subsession->initiate();
    }
    setupStreams();
}
 
--->
 
//setupStreams為遞歸函數(setupStreams-->continueAfterSETUP-->setupStreams)
//setupSubsession所有的子會話
setupStreams()
{
    while()
    {
        setupSubsession(subsession, streamUsingTCP, forceMulticastOnUnspecified, continueAfterSETUP);
    }
    startPlayingSession(session, initialSeekTime, endTime, scale, continueAfterPLAY);
}

3、以getOptions舉例

getOptions(continueAfterOPTIONS)，getOptions後怎麼調用到continueAfterOPTIONS的，如下:

//responseHandler* afterFunc 都由handler() 執行
getOptions(continueAfterOPTIONS)--->sendOptionsCommand()--->sendRequest()
{
--->openConnection()
{
    --->connectToServer()
    {
        setBackgroundHandling(,SOCKET_WRITABLE|SOCKET_EXCEPTION,connectionHandler,);
    }
 
    //連接配接server ok
    {
        setBackgroundHandling(,SOCKET_READABLE|SOCKET_EXCEPTION,incomingDataHandler,);
    }
}
 
if (connectionIsPending) {
      fRequestsAwaitingConnection.enqueue(request);
      return request->cseq();
    }
 
}
--->doEventLoop--->SingleStep()
{
    //socket狀态符合，就執行注冊好的函數，例如connectionHandler/incomingDataHandler等
    (*handler->handlerProc)(handler->clientData, resultConditionSet);
}
SingleStep()    //1th step,執行connectionHandler,SOCKET_WRITABLE
{
    handler->handlerProc = connectionHandler;
}
SingleStep()    //2th step,執行incomingDataHandler,SOCKET_READABLE
{
    handler->handlerProc = incomingDataHandler;
}
 
//incomingDataHandler會調用到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

● 先從setupStreams先入手吧

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;
}

● 再從FileSink::continuePlaying入手

FileSink::continuePlaying()

FramedSource::getNextFrame()

MultiFramedRTPSource::doGetNextFrame()

MultiFramedRTPSource::doGetNextFrame1()

//以下::僅表示static func聲明所在的類

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

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

struct timeval presentationTime,unsigned durationInMicroseconds);

MultiFramedRTPSource::doGetNextFrame1()

是遞歸函數，退出條件為

while (fNeedDelivery) //正常測試接收時，fNeedDelivery == 1
{
    if (nextPacket == NULL)
    {
       break;
    }
}

(Enter->Exit)：即時

(Enter,) ：和最近的(,Exit)配對

(,Exit)：和最近的(Enter,)配對

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

從第一次調用continuePlaying()跟蹤。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()-->

FileSink::afterGettingFrame(){addData();continuePlaying()}-->

4.2 step2th

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

doGetNextFrame1(Enter->Exit[nextPacket == NULL])--->static afterGettingFrame(,Exit)--->static afterGetting(,Exit)--->

doGetNextFrame1(,Exit[nextPacket == NULL])--->networkReadHandler1(,Eixt)--->

SingleStep()::2th--->incomingReportHandler1()--->

SingleStep()::3th--->incomingDataHandler1()--->continueAfterPLAY()--->

SingleStep()::4th--->

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

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

FileSink::afterGettingFrame(){addData();continuePlaying()}-->

//上述1/2th還有rtsp互動和一些初始化以及h264 SPS的處理，從3th就純粹了。

//當接收到一幀完整的幀才會調用static afterGetting()

//FileSink::afterGettingFrame(){addData();continuePlaying()}

//addData()：儲存一幀h264到檔案。continuePlaying()繼續幹活吧。

4.3 step3th

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

doGetNextFrame1(Enter->Exit[nextPacket == NULL])--->staticafterGettingFrame(,Exit)--->static afterGetting(,Exit)--->

doGetNextFrame1(,Exit[nextPacket == NULL])--->networkReadHandler1(,Eixt)--->

SingleStep()::5th--->

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

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

FileSink::afterGettingFrame(){addData();continuePlaying()}-->

4.4 step4th

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

doGetNextFrame1(Enter->Exit[nextPacket == NULL])--->staticafterGettingFrame(,Exit)--->static afterGetting(,Exit)--->

doGetNextFrame1( , Exit[nextPacket == NULL])--->networkReadHandler1(,Eixt)--->

//以上為針對3th的Exit，結合networkReadHandler1::3th(Enter,)和networkReadHandler1::4th(,Eixt)可以看出doGetNextFrame1為遞歸函數。

//networkReadHandler1--->doGetNextFrame1--->static afterGetting--->continuePlaying()--->doGetNextFrame1

// SingleStep()生生不息，networkReadHandler1()進進出出

SingleStep()::6th--->

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

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

FileSink::afterGettingFrame(){addData();continuePlaying()}-->

//nth ：multi-packet frame，會有多次SingleStep()，但不會調用static afterGetting()

//隻有在收完所有的sliece,即一個完整的frame後，才會調用static afterGetting()

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

doGetNextFrame1(Enter->Exit[nextPacket == NULL])--->static afterGettingFrame(,Exit)--->static afterGetting(,Exit)--->

doGetNextFrame1(,Exit[nextPacket == NULL])--->networkReadHandler1(,Eixt)--->

SingleStep()::nth--->

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

networkReadHandler1(,Exit)--->

SingleStep()::n+1th--->

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

networkReadHandler1(,Exit)--->

。。。。。。。。。。。。。

//最後一個packet

SingleStep()::n+mth--->

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

//此處才會調用static afterGetting

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

FileSink::afterGettingFrame(){addData();continuePlaying()}-->

//n+1th

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

doGetNextFrame1(Enter->Exit[nextPacket == NULL])--->static afterGettingFrame(,Exit)--->static afterGetting(,Exit)--->

doGetNextFrame1(,Exit[nextPacket == NULL])--->networkReadHandler1(,Eixt)--->

SingleStep()::n+m+1th--->

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

networkReadHandler1(,Exit)--->

。。。。。。。。。。。。。。。。

live555 client 接收rtp資料

1、live555的三種任務

2、rtsp互動

3、以getOptions舉例

4、client get rtp_packet

● 先從setupStreams先入手吧

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