amraudiortpsource.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

    // Strange TOC entry!
    fOurSource.envir() << "AMRBufferedPacket::nextEnclosedFrameSize(): invalid FT: " << FT << "\n";
    frameSize = 0; // This probably messes up the rest of this packet, but...
  }
#ifdef DEBUG
  fprintf(stderr, "AMRBufferedPacket::nextEnclosedFrameSize(): frame #: %d, FT: %d, isWideband: %d => frameSize: %d (dataSize: %d)\n", tocIndex, FT, fOurSource.isWideband(), frameSize, dataSize);
#endif
  ++fOurSource.frameIndex();

  if (dataSize < frameSize) return 0;
  return frameSize;
}

BufferedPacket* AMRBufferedPacketFactory
::createNewPacket(MultiFramedRTPSource* ourSource) {
  return new AMRBufferedPacket((RawAMRRTPSource&)(*ourSource));
}

///////// AMRDeinterleavingBuffer /////////
// (used to implement AMRDeinterleaver)

#define AMR_MAX_FRAME_SIZE 60

class AMRDeinterleavingBuffer {
public:
  AMRDeinterleavingBuffer(unsigned numChannels, unsigned maxInterleaveGroupSize);
  virtual ~AMRDeinterleavingBuffer();

  void deliverIncomingFrame(unsigned frameSize, RawAMRRTPSource* source,
			    struct timeval presentationTime);
  Boolean retrieveFrame(unsigned char* to, unsigned maxSize,
			unsigned& resultFrameSize, unsigned& resultNumTruncatedBytes,
			u_int8_t& resultFrameHeader,
			struct timeval& resultPresentationTime);

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

private:
  unsigned char* createNewBuffer();

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

    unsigned frameSize;
    unsigned char* frameData;
    u_int8_t frameHeader;
    struct timeval presentationTime;
  };

  unsigned fNumChannels, fMaxInterleaveGroupSize;
  FrameDescriptor* fFrames[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;
};


////////// AMRDeinterleaver implementation /////////

AMRDeinterleaver* AMRDeinterleaver
::createNew(UsageEnvironment& env,
	    Boolean isWideband, unsigned numChannels, unsigned maxInterleaveGroupSize,
	    RawAMRRTPSource* inputSource) {
  return new AMRDeinterleaver(env, isWideband, numChannels, maxInterleaveGroupSize,
			      inputSource);
}

AMRDeinterleaver::AMRDeinterleaver(UsageEnvironment& env,
				   Boolean isWideband, unsigned numChannels,
				   unsigned maxInterleaveGroupSize,
				   RawAMRRTPSource* inputSource)
  : AMRAudioSource(env, isWideband, numChannels),
    fInputSource(inputSource), fNeedAFrame(False) {
  fDeinterleavingBuffer
    = new AMRDeinterleavingBuffer(numChannels, maxInterleaveGroupSize);
}

AMRDeinterleaver::~AMRDeinterleaver() {
  delete fDeinterleavingBuffer;
  Medium::close(fInputSource);
}

static unsigned const uSecsPerFrame = 20000; // 20 ms

void AMRDeinterleaver::doGetNextFrame() {
  // First, try getting a frame from the deinterleaving buffer:
  if (fDeinterleavingBuffer->retrieveFrame(fTo, fMaxSize,
					   fFrameSize, fNumTruncatedBytes,
					   fLastFrameHeader, 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 AMRDeinterleaver
::afterGettingFrame(void* clientData, unsigned frameSize,
		    unsigned /*numTruncatedBytes*/,
		    struct timeval presentationTime,
		    unsigned /*durationInMicroseconds*/) {
  AMRDeinterleaver* deinterleaver = (AMRDeinterleaver*)clientData;
  deinterleaver->afterGettingFrame1(frameSize, presentationTime);
}

void AMRDeinterleaver
::afterGettingFrame1(unsigned frameSize, struct timeval presentationTime) {
  RawAMRRTPSource* source = (RawAMRRTPSource*)fInputSource;
  
  // First, put the frame into our deinterleaving buffer:
  fDeinterleavingBuffer->deliverIncomingFrame(frameSize, source, presentationTime);

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


////////// AMRDeinterleavingBuffer implementation /////////

AMRDeinterleavingBuffer
::AMRDeinterleavingBuffer(unsigned numChannels, unsigned maxInterleaveGroupSize)
  : fNumChannels(numChannels), fMaxInterleaveGroupSize(maxInterleaveGroupSize),
    fIncomingBankId(0), fIncomingBinMax(0),
    fOutgoingBinMax(0), fNextOutgoingBin(0),
    fHaveSeenPackets(False) {
  // Use two banks of descriptors - one for incoming, one for outgoing
  fFrames[0] = new FrameDescriptor[fMaxInterleaveGroupSize];
  fFrames[1] = new FrameDescriptor[fMaxInterleaveGroupSize];
  fInputBuffer = createNewBuffer();
}

AMRDeinterleavingBuffer::~AMRDeinterleavingBuffer() {
  delete[] fInputBuffer;
  delete[] fFrames[0]; delete[] fFrames[1];
}

void AMRDeinterleavingBuffer
::deliverIncomingFrame(unsigned frameSize, RawAMRRTPSource* source,
		       struct timeval presentationTime) {
  unsigned char const ILL = source->ILL();
  unsigned char const ILP = source->ILP();
  unsigned frameIndex = source->frameIndex();
  unsigned short packetSeqNum = source->curPacketRTPSeqNum();

  // First perform a sanity check on the parameters:
  // (This is overkill, as the source should have already done this.)
  if (ILP > ILL || frameIndex == 0) {
#ifdef DEBUG
    fprintf(stderr, "AMRDeinterleavingBuffer::deliverIncomingFrame() param sanity check failed (%d,%d,%d,%d)\n", frameSize, ILL, ILP, frameIndex);
#endif
    exit(1);
  }

  --frameIndex; // because it was incremented by the source when this frame was read 
  u_int8_t frameHeader;
  if (frameIndex >= source->TOCSize()) { // sanity check
    frameHeader = FT_NO_DATA<<3;
  } else {
    frameHeader = source->TOC()[frameIndex];
  }

  unsigned frameBlockIndex = frameIndex/fNumChannels;
  unsigned frameWithinFrameBlock = frameIndex%fNumChannels;

  // The input "presentationTime" was that of the first frame-block in this
  // packet.  Update it for the current frame:
  unsigned uSecIncrement = frameBlockIndex*(ILL+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 + frameBlockIndex)) {
    // We've moved to a new interleave group
#ifdef DEBUG
    fprintf(stderr, "AMRDeinterleavingBuffer::deliverIncomingFrame(): new interleave group\n");
#endif
    fHaveSeenPackets = True;
    fLastPacketSeqNumForGroup = packetSeqNum + ILL - ILP;

    // 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
    = ((ILP + frameBlockIndex*(ILL+1))*fNumChannels + frameWithinFrameBlock)
      % fMaxInterleaveGroupSize; // the % is for sanity
#ifdef DEBUG
  fprintf(stderr, "AMRDeinterleavingBuffer::deliverIncomingFrame(): frameIndex %d (%d,%d) put in bank %d, bin %d (%d): size %d, header 0x%02x, presentationTime %lu.%06ld\n", frameIndex, frameBlockIndex, frameWithinFrameBlock, fIncomingBankId, binNumber, fMaxInterleaveGroupSize, frameSize, frameHeader, presentationTime.tv_sec, presentationTime.tv_usec);
#endif
  FrameDescriptor& inBin = fFrames[fIncomingBankId][binNumber];
  unsigned char* curBuffer = inBin.frameData;
  inBin.frameData = fInputBuffer;
  inBin.frameSize = frameSize;
  inBin.frameHeader = frameHeader;
  inBin.presentationTime = presentationTime;

  if (curBuffer == NULL) curBuffer = createNewBuffer();
  fInputBuffer = curBuffer;

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

Boolean AMRDeinterleavingBuffer
::retrieveFrame(unsigned char* to, unsigned maxSize,
		unsigned& resultFrameSize, unsigned& resultNumTruncatedBytes,
		u_int8_t& resultFrameHeader,
		struct timeval& resultPresentationTime) {
  if (fNextOutgoingBin >= fOutgoingBinMax) return False; // none left

  FrameDescriptor& outBin = fFrames[fIncomingBankId^1][fNextOutgoingBin];
  unsigned char* fromPtr = outBin.frameData;
  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 a FT_NO_DATA frame:
  if (fromSize == 0) {
    resultFrameHeader = FT_NO_DATA<<3;

    // 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:
    resultFrameHeader = outBin.frameHeader;
    resultPresentationTime = outBin.presentationTime;
  }

  fLastRetrievedPresentationTime = resultPresentationTime;

  if (fromSize > maxSize) {
    resultNumTruncatedBytes = fromSize - maxSize;
    resultFrameSize = maxSize;
  } else {
    resultNumTruncatedBytes = 0;
    resultFrameSize = fromSize;
  }
  memmove(to, fromPtr, resultFrameSize);
#ifdef DEBUG
  fprintf(stderr, "AMRDeinterleavingBuffer::retrieveFrame(): from bank %d, bin %d: size %d, header 0x%02x, presentationTime %lu.%06ld\n", fIncomingBankId^1, fNextOutgoingBin, resultFrameSize, resultFrameHeader, resultPresentationTime.tv_sec, resultPresentationTime.tv_usec);
#endif

  ++fNextOutgoingBin;
  return True;
}

unsigned char* AMRDeinterleavingBuffer::createNewBuffer() {
  return new unsigned char[inputBufferSize()];
}

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

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

// Unpack bandwidth-aligned data to octet-aligned:
static unsigned short frameBitsFromFT[16] = {
  95, 103, 118, 134,
  148, 159, 204, 244,
  39, 0, 0, 0,
  0, 0, 0, 0
};
static unsigned short frameBitsFromFTWideband[16] = {
  132, 177, 253, 285,
  317, 365, 397, 461,
  477, 40, 0, 0,
  0, 0, 0, 0
};

static void unpackBandwidthEfficientData(BufferedPacket* packet,
					 Boolean isWideband) {
#ifdef DEBUG
  fprintf(stderr, "Unpacking 'bandwidth-efficient' payload (%d bytes):\n", packet->dataSize());
  for (unsigned j = 0; j < packet->dataSize(); ++j) {
    fprintf(stderr, "%02x:", (packet->data())[j]);
  }
  fprintf(stderr, "\n");
#endif
  BitVector fromBV(packet->data(), 0, 8*packet->dataSize());

  unsigned const toBufferSize = 2*packet->dataSize(); // conservatively large
  unsigned char* toBuffer = new unsigned char[toBufferSize];
  unsigned toCount = 0;

  // Begin with the payload header:
  unsigned CMR = fromBV.getBits(4);
  toBuffer[toCount++] = CMR << 4;

  // Then, run through and unpack the TOC entries:
  while (1) {
    unsigned toc = fromBV.getBits(6);
    toBuffer[toCount++] = toc << 2;

    if ((toc&0x20) == 0) break; // the F bit is 0
  }

  // Then, using the TOC data, unpack each frame payload:
  unsigned const tocSize = toCount - 1;
  for (unsigned i = 1; i <= tocSize; ++i) {
    unsigned char tocByte = toBuffer[i];
    unsigned char const FT = (tocByte&0x78) >> 3;
    unsigned short frameSizeBits
      = isWideband ? frameBitsFromFTWideband[FT] : frameBitsFromFT[FT];
    unsigned short frameSizeBytes = (frameSizeBits+7)/8;

    shiftBits(&toBuffer[toCount], 0, // to
	      packet->data(), fromBV.curBitIndex(), // from
	      frameSizeBits // num bits
	      );
#ifdef DEBUG
    if (frameSizeBits > fromBV.numBitsRemaining()) {
      fprintf(stderr, "\tWarning: Unpacking frame %d of %d: want %d bits, but only %d are available!\n", i, tocSize, frameSizeBits, fromBV.numBitsRemaining());
    }
#endif
    fromBV.skipBits(frameSizeBits);
    toCount += frameSizeBytes;
  }  

#ifdef DEBUG
  if (fromBV.numBitsRemaining() > 7) {
    fprintf(stderr, "\tWarning: %d bits remain unused!\n", fromBV.numBitsRemaining());
  }
#endif

  // Finally, replace the current packet data with the unpacked data:
  packet->removePadding(packet->dataSize()); // throws away current packet data
  packet->appendData(toBuffer, toCount);
  delete[] toBuffer;
}