qcelpaudiortpsource.cpp

流媒体传输协议的实现代码,非常有用.可以支持rtsp mms等流媒体传输协议

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///////// QCELPDeinterleavingBuffer /////////
// (used to implement QCELPDeinterleaver)

#define QCELP_MAX_FRAME_SIZE 35
#define QCELP_MAX_INTERLEAVE_L 5
#define QCELP_MAX_FRAMES_PER_PACKET 10
#define QCELP_MAX_INTERLEAVE_GROUP_SIZE \
    ((QCELP_MAX_INTERLEAVE_L+1)*QCELP_MAX_FRAMES_PER_PACKET)

class QCELPDeinterleavingBuffer {
public:
  QCELPDeinterleavingBuffer();
  virtual ~QCELPDeinterleavingBuffer();

  void deliverIncomingFrame(unsigned frameSize,
			    unsigned char interleaveL,
			    unsigned char interleaveN,
			    unsigned char frameIndex,
			    unsigned short packetSeqNum,
			    struct timeval presentationTime);
  Boolean retrieveFrame(unsigned char* to, unsigned maxSize,
			unsigned& resultFrameSize, unsigned& resultNumTruncatedBytes,
			struct timeval& resultPresentationTime);

  unsigned char* inputBuffer() { return fInputBuffer; }
  unsigned inputBufferSize() const { return QCELP_MAX_FRAME_SIZE; }

private:
  class FrameDescriptor {
  public:
    FrameDescriptor();
    virtual ~FrameDescriptor();

    unsigned frameSize;
    unsigned char* frameData;
    struct timeval presentationTime;
  };

  // Use two banks of descriptors - one for incoming, one for outgoing
  FrameDescriptor fFrames[QCELP_MAX_INTERLEAVE_GROUP_SIZE][2];
  unsigned char fIncomingBankId; // toggles between 0 and 1
  unsigned char fIncomingBinMax; // in the incoming bank
  unsigned char fOutgoingBinMax; // in the outgoing bank
  unsigned char fNextOutgoingBin;
  Boolean fHaveSeenPackets;
  u_int16_t fLastPacketSeqNumForGroup;
  unsigned char* fInputBuffer;
  struct timeval fLastRetrievedPresentationTime;
};


////////// QCELPDeinterleaver implementation /////////

QCELPDeinterleaver*
QCELPDeinterleaver::createNew(UsageEnvironment& env,
			      RawQCELPRTPSource* inputSource) {
  return new QCELPDeinterleaver(env, inputSource);
}

QCELPDeinterleaver::QCELPDeinterleaver(UsageEnvironment& env,
				       RawQCELPRTPSource* inputSource)
  : FramedFilter(env, inputSource),
    fNeedAFrame(False) {
  fDeinterleavingBuffer = new QCELPDeinterleavingBuffer();
}

QCELPDeinterleaver::~QCELPDeinterleaver() {
  delete fDeinterleavingBuffer;
}

static unsigned const uSecsPerFrame = 20000; // 20 ms

void QCELPDeinterleaver::doGetNextFrame() {
  // First, try getting a frame from the deinterleaving buffer:
  if (fDeinterleavingBuffer->retrieveFrame(fTo, fMaxSize,
					   fFrameSize, fNumTruncatedBytes,
					   fPresentationTime)) {
    // Success!
    fNeedAFrame = False;

    fDurationInMicroseconds = uSecsPerFrame;

    // Call our own 'after getting' function.  Because we're not a 'leaf'
    // source, we can call this directly, without risking
    // infinite recursion
    afterGetting(this);
    return;
  }

  // No luck, so ask our source for help:
  fNeedAFrame = True;
  if (!fInputSource->isCurrentlyAwaitingData()) {
    fInputSource->getNextFrame(fDeinterleavingBuffer->inputBuffer(),
			       fDeinterleavingBuffer->inputBufferSize(),
			       afterGettingFrame, this,
			       FramedSource::handleClosure, this);
  }
}

void QCELPDeinterleaver
::afterGettingFrame(void* clientData, unsigned frameSize,
		    unsigned /*numTruncatedBytes*/,
		    struct timeval presentationTime,
		    unsigned /*durationInMicroseconds*/) {
  QCELPDeinterleaver* deinterleaver = (QCELPDeinterleaver*)clientData;
  deinterleaver->afterGettingFrame1(frameSize, presentationTime);
}

void QCELPDeinterleaver
::afterGettingFrame1(unsigned frameSize, struct timeval presentationTime) {
  RawQCELPRTPSource* source = (RawQCELPRTPSource*)fInputSource;
  
  // First, put the frame into our deinterleaving buffer:
  fDeinterleavingBuffer
    ->deliverIncomingFrame(frameSize, source->interleaveL(),
			   source->interleaveN(), source->frameIndex(),
			   source->curPacketRTPSeqNum(),
			   presentationTime);  

  // Then, try delivering a frame to the client (if he wants one):
  if (fNeedAFrame) doGetNextFrame();
}


////////// QCELPDeinterleavingBuffer implementation /////////

QCELPDeinterleavingBuffer::QCELPDeinterleavingBuffer()
  : fIncomingBankId(0), fIncomingBinMax(0),
    fOutgoingBinMax(0), fNextOutgoingBin(0),
    fHaveSeenPackets(False) {
  fInputBuffer = new unsigned char[QCELP_MAX_FRAME_SIZE];
}

QCELPDeinterleavingBuffer::~QCELPDeinterleavingBuffer() {
  delete[] fInputBuffer;
}

void QCELPDeinterleavingBuffer
::deliverIncomingFrame(unsigned frameSize,
		       unsigned char interleaveL,
		       unsigned char interleaveN,
		       unsigned char frameIndex,
		       unsigned short packetSeqNum,
		       struct timeval presentationTime) {
  // First perform a sanity check on the parameters:
  // (This is overkill, as the source should have already done this.)
  if (frameSize > QCELP_MAX_FRAME_SIZE
      || interleaveL > QCELP_MAX_INTERLEAVE_L || interleaveN > interleaveL
      || frameIndex == 0 || frameIndex > QCELP_MAX_FRAMES_PER_PACKET) {
#ifdef DEBUG
    fprintf(stderr, "QCELPDeinterleavingBuffer::deliverIncomingFrame() param sanity check failed (%d,%d,%d,%d)\n", frameSize, interleaveL, interleaveN, frameIndex);
#endif
    exit(1);
  }

  // The input "presentationTime" was that of the first frame in this
  // packet.  Update it for the current frame:
  unsigned uSecIncrement = (frameIndex-1)*(interleaveL+1)*uSecsPerFrame;
  presentationTime.tv_usec += uSecIncrement;
  presentationTime.tv_sec += presentationTime.tv_usec/1000000;
  presentationTime.tv_usec = presentationTime.tv_usec%1000000;

  // Next, check whether this packet is part of a new interleave group
  if (!fHaveSeenPackets
      || seqNumLT(fLastPacketSeqNumForGroup, packetSeqNum)) {
    // We've moved to a new interleave group
    fHaveSeenPackets = True;
    fLastPacketSeqNumForGroup = packetSeqNum + interleaveL - interleaveN;

    // Switch the incoming and outgoing banks:
    fIncomingBankId ^= 1;
    unsigned char tmp = fIncomingBinMax;
    fIncomingBinMax = fOutgoingBinMax;
    fOutgoingBinMax = tmp; 
    fNextOutgoingBin = 0;
  }

  // Now move the incoming frame into the appropriate bin:
  unsigned const binNumber
    = interleaveN + (frameIndex-1)*(interleaveL+1);
  FrameDescriptor& inBin = fFrames[binNumber][fIncomingBankId];
  unsigned char* curBuffer = inBin.frameData;
  inBin.frameData = fInputBuffer;
  inBin.frameSize = frameSize;
  inBin.presentationTime = presentationTime;

  if (curBuffer == NULL) curBuffer = new unsigned char[QCELP_MAX_FRAME_SIZE];
  fInputBuffer = curBuffer;

  if (binNumber >= fIncomingBinMax) {
    fIncomingBinMax = binNumber + 1;
  }
}

Boolean QCELPDeinterleavingBuffer
::retrieveFrame(unsigned char* to, unsigned maxSize,
		unsigned& resultFrameSize, unsigned& resultNumTruncatedBytes,
		struct timeval& resultPresentationTime) {
  if (fNextOutgoingBin >= fOutgoingBinMax) return False; // none left

  FrameDescriptor& outBin = fFrames[fNextOutgoingBin][fIncomingBankId^1];
  unsigned char* fromPtr;
  unsigned char fromSize = outBin.frameSize;
  outBin.frameSize = 0; // for the next time this bin is used

  // Check whether this frame is missing; if so, return an 'erasure' frame:
  unsigned char erasure = 14;
  if (fromSize == 0) {
    fromPtr = &erasure;
    fromSize = 1;

    // Compute this erasure frame's presentation time via extrapolation:
    resultPresentationTime = fLastRetrievedPresentationTime;
    resultPresentationTime.tv_usec += uSecsPerFrame;
    if (resultPresentationTime.tv_usec >= 1000000) {
      ++resultPresentationTime.tv_sec;
      resultPresentationTime.tv_usec -= 1000000;
    }
  } else {
    // Normal case - a frame exists:
    fromPtr = outBin.frameData;
    resultPresentationTime = outBin.presentationTime;
  }

  fLastRetrievedPresentationTime = resultPresentationTime;

  if (fromSize > maxSize) {
    resultNumTruncatedBytes = fromSize - maxSize;
    resultFrameSize = maxSize;
  } else {
    resultNumTruncatedBytes = 0;
    resultFrameSize = fromSize;
  }
  memmove(to, fromPtr, resultFrameSize);

  ++fNextOutgoingBin;
  return True;
}

QCELPDeinterleavingBuffer::FrameDescriptor::FrameDescriptor()
  : frameSize(0), frameData(NULL) {
}

QCELPDeinterleavingBuffer::FrameDescriptor::~FrameDescriptor() {
  delete[] frameData;
}