liveMedia/TheoraVideoRTPSource.cpp

/**********
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FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for
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**********/
// "liveMedia"
// Copyright (c) 1996-2020 Live Networks, Inc.  All rights reserved.
// Theora Video RTP Sources
// Implementation

#include "TheoraVideoRTPSource.hh"

////////// TheoraBufferedPacket and TheoraBufferedPacketFactory //////////

class TheoraBufferedPacket: public BufferedPacket {
public:
  TheoraBufferedPacket();
  virtual ~TheoraBufferedPacket();

private: // redefined virtual functions
  virtual unsigned nextEnclosedFrameSize(unsigned char*& framePtr,
					 unsigned dataSize);
};

class TheoraBufferedPacketFactory: public BufferedPacketFactory {
private: // redefined virtual functions
  virtual BufferedPacket* createNewPacket(MultiFramedRTPSource* ourSource);
};


///////// TheoraVideoRTPSource implementation ////////

TheoraVideoRTPSource*
TheoraVideoRTPSource::createNew(UsageEnvironment& env, Groupsock* RTPgs,
				unsigned char rtpPayloadFormat) {
  return new TheoraVideoRTPSource(env, RTPgs, rtpPayloadFormat);
}

TheoraVideoRTPSource
::TheoraVideoRTPSource(UsageEnvironment& env, Groupsock* RTPgs,
		       unsigned char rtpPayloadFormat)
  : MultiFramedRTPSource(env, RTPgs, rtpPayloadFormat, 90000,
			 new TheoraBufferedPacketFactory),
    fCurPacketIdent(0) {
}

TheoraVideoRTPSource::~TheoraVideoRTPSource() {
}

Boolean TheoraVideoRTPSource
::processSpecialHeader(BufferedPacket* packet,
                       unsigned& resultSpecialHeaderSize) {
  unsigned char* headerStart = packet->data();
  unsigned packetSize = packet->dataSize();

  resultSpecialHeaderSize = 4;
  if (packetSize < resultSpecialHeaderSize) return False; // packet was too small

  // The first 3 bytes of the header are the "Ident" field:
  fCurPacketIdent = (headerStart[0]<<16) | (headerStart[1]<<8) | headerStart[2];

  // The 4th byte is F|TDT|numPkts.
  // Reject any packet with TDT == 3:
  if ((headerStart[3]&0x30) == 0x30) return False;

  u_int8_t F = headerStart[3]>>6;
  fCurrentPacketBeginsFrame = F <= 1; // "Not Fragmented" or "Start Fragment"
  fCurrentPacketCompletesFrame = F == 0 || F == 3; // "Not Fragmented" or "End Fragment"

  return True;
}

char const* TheoraVideoRTPSource::MIMEtype() const {
  return "video/THEORA";
}


////////// TheoraBufferedPacket and TheoraBufferedPacketFactory implementation //////////

TheoraBufferedPacket::TheoraBufferedPacket() {
}

TheoraBufferedPacket::~TheoraBufferedPacket() {
}

unsigned TheoraBufferedPacket
::nextEnclosedFrameSize(unsigned char*& framePtr, unsigned dataSize) {
  if (dataSize < 2) {
    // There's not enough space for a 2-byte header.  TARFU!  Just return the data that's left:
    return dataSize;
  }

  unsigned frameSize = (framePtr[0]<<8) | framePtr[1];
  framePtr += 2;
  if (frameSize > dataSize - 2) return dataSize - 2; // inconsistent frame size => just return all the data that's left

  return frameSize;
}

BufferedPacket* TheoraBufferedPacketFactory
::createNewPacket(MultiFramedRTPSource* /*ourSource*/) {
  return new TheoraBufferedPacket();
}