mpeg2indexfromtransportstream.cpp

H.264 RTSP 串流(live 555)視窗版本

/**********
This library is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the
Free Software Foundation; either version 2.1 of the License, or (at your
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This library is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for
more details.

You should have received a copy of the GNU Lesser General Public License
along with this library; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301  USA
**********/
// "liveMedia"
// Copyright (c) 1996-2010 Live Networks, Inc.  All rights reserved.
// A filter that produces a sequence of I-frame indices from a MPEG-2 Transport Stream
// Implementation

#include "MPEG2IndexFromTransportStream.hh"

////////// IndexRecord definition //////////

enum RecordType {
  RECORD_UNPARSED = 0,
  RECORD_VSH = 1,
  RECORD_GOP = 2,
  RECORD_PIC_NON_IFRAME = 3, // includes slices
  RECORD_PIC_IFRAME = 4, // includes slices
  RECORD_JUNK
};

class IndexRecord {
public:
  IndexRecord(u_int8_t startOffset, u_int8_t size,
	      unsigned long transportPacketNumber, float pcr);
  virtual ~IndexRecord();

  RecordType& recordType() { return fRecordType; }
  void setFirstFlag() { fRecordType = (RecordType)(((u_int8_t)fRecordType) | 0x80); }
  u_int8_t startOffset() const { return fStartOffset; }
  u_int8_t& size() { return fSize; }
  float pcr() const { return fPCR; }
  unsigned long transportPacketNumber() const { return fTransportPacketNumber; }

  IndexRecord* next() const { return fNext; }
  void addAfter(IndexRecord* prev);
  void unlink();

private:
  // Index records are maintained in a doubly-linked list:
  IndexRecord* fNext;
  IndexRecord* fPrev;

  RecordType fRecordType;
  u_int8_t fStartOffset; // within the Transport Stream packet
  u_int8_t fSize; // in bytes, following "fStartOffset".
  // Note: fStartOffset + fSize <= TRANSPORT_PACKET_SIZE
  float fPCR;
  unsigned long fTransportPacketNumber;
};

#ifdef DEBUG
static char const* recordTypeStr[] = {
  "UNPARSED",
  "VSH",
  "GOP",
  "PIC(non-I-frame)",
  "PIC(I-frame)",
  "JUNK"
};
UsageEnvironment& operator<<(UsageEnvironment& env, IndexRecord& r) {
  return env << "[" << ((r.recordType()&0x80) != 0 ? "1" : "")
	     << recordTypeStr[r.recordType()&0x7F] << ":"
	     << (unsigned)r.transportPacketNumber() << ":" << r.startOffset()
	     << "(" << r.size() << ")@" << r.pcr() << "]";
}
#endif


////////// MPEG2IFrameIndexFromTransportStream implementation //////////

MPEG2IFrameIndexFromTransportStream*
MPEG2IFrameIndexFromTransportStream::createNew(UsageEnvironment& env,
					       FramedSource* inputSource) {
  return new MPEG2IFrameIndexFromTransportStream(env, inputSource);
}

// The largest expected frame size (in bytes):
#define MAX_FRAME_SIZE 400000

// Make our parse buffer twice as large as this, to ensure that at least one
// complete frame will fit inside it:
#define PARSE_BUFFER_SIZE (2*MAX_FRAME_SIZE)

// The PID used for the PAT (as defined in the MPEG Transport Stream standard):
#define PAT_PID 0

MPEG2IFrameIndexFromTransportStream
::MPEG2IFrameIndexFromTransportStream(UsageEnvironment& env,
				      FramedSource* inputSource)
  : FramedFilter(env, inputSource),
    fInputTransportPacketCounter((unsigned)-1), fClosureNumber(0),
    fLastContinuityCounter(~0),
    fFirstPCR(0.0), fLastPCR(0.0), fHaveSeenFirstPCR(False),
    fPMT_PID(0x10), fVideo_PID(0xE0), // default values
    fParseBufferSize(PARSE_BUFFER_SIZE),
    fParseBufferFrameStart(0), fParseBufferParseEnd(4), fParseBufferDataEnd(0),
    fHeadIndexRecord(NULL), fTailIndexRecord(NULL) {
  fParseBuffer = new unsigned char[fParseBufferSize];
}

MPEG2IFrameIndexFromTransportStream::~MPEG2IFrameIndexFromTransportStream() {
  delete fHeadIndexRecord;
  delete[] fParseBuffer;
}

void MPEG2IFrameIndexFromTransportStream::doGetNextFrame() {
  // Begin by trying to deliver an index record (for an already-parsed frame)
  // to the client:
  if (deliverIndexRecord()) return;

  // No more index records are left to deliver, so try to parse a new frame:
  if (parseFrame()) { // success - try again
    doGetNextFrame();
    return;
  }

  // We need to read some more Transport Stream packets.  Check whether we have room:
  if (fParseBufferSize - fParseBufferDataEnd < TRANSPORT_PACKET_SIZE) {
    // There's no room left.  Compact the buffer, and check again:
    compactParseBuffer();
    if (fParseBufferSize - fParseBufferDataEnd < TRANSPORT_PACKET_SIZE) {
      envir() << "ERROR: parse buffer full; increase MAX_FRAME_SIZE\n";
      // Treat this as if the input source ended:
      handleInputClosure1();
      return;
    }
  }

  // Arrange to read a new Transport Stream packet:
  fInputSource->getNextFrame(fInputBuffer, sizeof fInputBuffer,
			     afterGettingFrame, this,
			     handleInputClosure, this);
}

void MPEG2IFrameIndexFromTransportStream
::afterGettingFrame(void* clientData, unsigned frameSize,
		    unsigned numTruncatedBytes,
		    struct timeval presentationTime,
		    unsigned durationInMicroseconds) {
  MPEG2IFrameIndexFromTransportStream* source
    = (MPEG2IFrameIndexFromTransportStream*)clientData;
  source->afterGettingFrame1(frameSize, numTruncatedBytes,
			     presentationTime, durationInMicroseconds);
}

void MPEG2IFrameIndexFromTransportStream
::afterGettingFrame1(unsigned frameSize,
		     unsigned numTruncatedBytes,
		     struct timeval presentationTime,
		     unsigned durationInMicroseconds) {
  if (frameSize < TRANSPORT_PACKET_SIZE || fInputBuffer[0] != 0x47/*sync byte*/) {
    if (fInputBuffer[0] != 0x47) {
      envir() << "Bad TS sync byte: 0x" << fInputBuffer[0] << "\n";
    }
    // Handle this as if the source ended:
    handleInputClosure1();
    return;
  }

  ++fInputTransportPacketCounter;

  // Figure out how much of this Transport Packet contains PES data:
  u_int8_t adaptation_field_control = (fInputBuffer[3]&0x30)>>4;
  u_int8_t totalHeaderSize
    = adaptation_field_control == 1 ? 4 : 5 + fInputBuffer[4];

  // Check for a PCR:
  if (totalHeaderSize > 5 && (fInputBuffer[5]&0x10) != 0) {
    // There's a PCR:
    u_int32_t pcrBaseHigh
      = (fInputBuffer[6]<<24)|(fInputBuffer[7]<<16)
      |(fInputBuffer[8]<<8)|fInputBuffer[9];
    float pcr = pcrBaseHigh/45000.0f;
    if ((fInputBuffer[10]&0x80) != 0) pcr += 1/90000.0f; // add in low-bit (if set)
    unsigned short pcrExt = ((fInputBuffer[10]&0x01)<<8) | fInputBuffer[11];
    pcr += pcrExt/27000000.0f;

    if (!fHaveSeenFirstPCR) {
      fFirstPCR = pcr;
      fHaveSeenFirstPCR = True;
    }
    fLastPCR = pcr;
  }

  // Get the PID from the packet, and check for special tables: the PAT and PMT:
  u_int16_t PID = ((fInputBuffer[1]&0x1F)<<8) | fInputBuffer[2];
  if (PID == PAT_PID) {
    analyzePAT(&fInputBuffer[totalHeaderSize], TRANSPORT_PACKET_SIZE-totalHeaderSize);
  } else if (PID == fPMT_PID) {
    analyzePMT(&fInputBuffer[totalHeaderSize], TRANSPORT_PACKET_SIZE-totalHeaderSize);
  }

  // Ignore transport packets for non-video programs,
  // or packets with no data, or packets that duplicate the previous packet:
  u_int8_t continuity_counter = fInputBuffer[3]&0x0F;
  if ((PID != fVideo_PID) ||
      !(adaptation_field_control == 1  || adaptation_field_control == 3) ||
      continuity_counter == fLastContinuityCounter) {
    doGetNextFrame();
    return;
  }
  fLastContinuityCounter = continuity_counter;

  // Also, if this is the start of a PES packet, then skip over the PES header:
  Boolean payload_unit_start_indicator = (fInputBuffer[1]&0x40) != 0;
  //fprintf(stderr, "PUSI: %d\n", payload_unit_start_indicator);//#####
  if (payload_unit_start_indicator) {
    // Note: The following works only for MPEG-2 data #####
    u_int8_t PES_header_data_length = fInputBuffer[totalHeaderSize+8];
    //fprintf(stderr, "PES_header_data_length: %d\n", PES_header_data_length);//#####
    totalHeaderSize += 9 + PES_header_data_length;
    if (totalHeaderSize >= TRANSPORT_PACKET_SIZE) {
      envir() << "Unexpectedly large PES header size: " << PES_header_data_length << "\n";
      // Handle this as if the source ended:
      handleInputClosure1();
      return;
    }
  }

  // The remaining data is Video Elementary Stream data.  Add it to our parse buffer:
  unsigned vesSize = TRANSPORT_PACKET_SIZE - totalHeaderSize;
  memmove(&fParseBuffer[fParseBufferDataEnd], &fInputBuffer[totalHeaderSize], vesSize);
  fParseBufferDataEnd += vesSize;

  // And add a new index record noting where it came from:
  addToTail(new IndexRecord(totalHeaderSize, vesSize, fInputTransportPacketCounter,
			    fLastPCR - fFirstPCR));

  // Try again:
  doGetNextFrame();
}

void MPEG2IFrameIndexFromTransportStream::handleInputClosure(void* clientData) {
  MPEG2IFrameIndexFromTransportStream* source
    = (MPEG2IFrameIndexFromTransportStream*)clientData;
  source->handleInputClosure1();
}

#define VIDEO_SEQUENCE_START_CODE 0xB3		// MPEG-1 or 2
#define VISUAL_OBJECT_SEQUENCE_START_CODE 0xB0	// MPEG-4
#define GROUP_START_CODE 0xB8			// MPEG-1 or 2
#define GROUP_VOP_START_CODE 0xB3		// MPEG-4
#define PICTURE_START_CODE 0x00			// MPEG-1 or 2
#define VOP_START_CODE 0xB6			// MPEG-4

void MPEG2IFrameIndexFromTransportStream::handleInputClosure1() {
  if (++fClosureNumber == 1 && fParseBufferDataEnd > fParseBufferFrameStart
      && fParseBufferDataEnd <= fParseBufferSize - 4) {
    // This is the first time we saw EOF, and there's still data remaining to be
    // parsed.  Hack: Append a Picture Header code to the end of the unparsed
    // data, and try again.  This should use up all of the unparsed data.
    fParseBuffer[fParseBufferDataEnd++] = 0;
    fParseBuffer[fParseBufferDataEnd++] = 0;
    fParseBuffer[fParseBufferDataEnd++] = 1;
    fParseBuffer[fParseBufferDataEnd++] = PICTURE_START_CODE;

    // Try again:
    doGetNextFrame();
  } else {
    // Handle closure in the regular way:
    FramedSource::handleClosure(this);
  }
}

void MPEG2IFrameIndexFromTransportStream
::analyzePAT(unsigned char* pkt, unsigned size) {
  // Get the PMT_PID:
  while (size >= 17) { // The table is large enough
    u_int16_t program_number = (pkt[9]<<8) | pkt[10];
    if (program_number != 0) {
      fPMT_PID = ((pkt[11]&0x1F)<<8) | pkt[12];
      return;
    }

    pkt += 4; size -= 4;
  }
}

void MPEG2IFrameIndexFromTransportStream
::analyzePMT(unsigned char* pkt, unsigned size) {
  // Scan the "elementary_PID"s in the map, until we see the first video stream.

  // First, get the "section_length", to get the table's size: