live555 client 接收rtp數據

轉自https://blog.csdn.net/freezlz/article/details/21044315
2014-03-08 22:05:58

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

以下爲我所見所得，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);

//註冊
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);

//註冊
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。

//註冊

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交互
//OPTIONS—>DESCRIBE—>SETUP—>PLAY，這是最通用的交互了。

getOptions()—>continueAfterOPTIONS()—>

getSDPDescription()—>continueAfterDESCRIBE()
{

session = MediaSession::createNew(*env, sdpDescription);

while()
{
    //音視頻子會話
    subsession->initiate();
}
setupStreams();

}

—>

//setupStreams爲遞歸函數(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server ok
{
    setBackgroundHandling(,SOCKET_READABLE|SOCKET_EXCEPTION,incomingDataHandler,);
}

}

if (connectionIsPending) {
fRequestsAwaitingConnection.enqueue(request);
return request->cseq();
}

}
—>doEventLoop—>SingleStep()
{
//socket狀態符合，就執行註冊好的函數，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，退出條件爲

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交互和一些初始化以及h264 SPS的處理，從3th就純粹了。

//當接收到一幀完整的幀纔會調用static afterGetting()

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

//addData()：保存一幀h264到文件。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)—>

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

//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()

//只有在收完所有的sliece,即一個完整的frame後，纔會調用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,)—>

//此處纔會調用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)—>

。。。。。。。。。。。。。。。。

作者：無風也流
來源：CSDN
原文：https://blog.csdn.net/freezlz/article/details/21044315
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