liveMedia/MPEG2TransportStreamParser_PAT.cpp

/**********
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 3 of the License, or (at your
option) any later version. (See <http://www.gnu.org/copyleft/lesser.html>.)

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) 1996-2020 Live Networks, Inc.  All rights reserved.
// A parser for a MPEG Transport Stream
// Implementation

#include "MPEG2TransportStreamParser.hh"

void MPEG2TransportStreamParser::parsePAT(Boolean pusi, unsigned numDataBytes) {
#ifdef DEBUG_CONTENTS
  fprintf(stderr, "\tProgram Association Table\n");
#endif 
  unsigned startPos = curOffset();

  do {
    if (pusi) {
      u_int8_t pointer_field = get1Byte();
      skipBytes(pointer_field); // usually 0
    }

    u_int8_t table_id = get1Byte();
    if (table_id != 0x00) {
#ifdef DEBUG_ERRORS
      fprintf(stderr, "MPEG2TransportStreamParser::parsePAT(%d, %d): bad table_id: 0x%02x\n",
	      pusi, numDataBytes, table_id);
#endif
      break;
    }

    u_int16_t flagsPlusSection_length = get2Bytes();
    u_int16_t section_length = flagsPlusSection_length&0x0FFF;
#ifdef DEBUG_CONTENTS
    fprintf(stderr, "\t\tsection_length: %d\n", section_length);
#endif
    if (section_length < 9/*too small for remaining fields + CRC*/ ||
	section_length > 1021/*as per specification*/) {
#ifdef DEBUG_ERRORS
      fprintf(stderr, "MPEG2TransportStreamParser::parsePAT(%d, %d): Bad section_length: %d\n",
	      pusi, numDataBytes, section_length);
#endif
      break;
    }

    unsigned endPos = curOffset() + section_length;
    if (endPos - startPos > numDataBytes) {
#ifdef DEBUG_ERRORS
      fprintf(stderr, "MPEG2TransportStreamParser::parsePAT(%d, %d): section_length %d gives us a total size %d that's too large!\n",
	      pusi, numDataBytes, section_length, endPos - startPos);
#endif
      break;
    }

#ifdef DEBUG_CONTENTS
    u_int16_t transport_stream_id = get2Bytes();
    fprintf(stderr, "\t\ttransport_stream_id: 0x%04x\n", transport_stream_id);
    u_int8_t version_number_byte = get1Byte();
    u_int8_t version_number = (version_number_byte&0x1E)>>1;
    u_int8_t section_number = get1Byte();
    u_int8_t last_section_number = get1Byte();
    fprintf(stderr, "\t\tversion_number: %d; section_number: %d; last_section_number: %d\n",
	    version_number, section_number, last_section_number);
#else
    skipBytes(5);
#endif

    while (curOffset() <= endPos - 4/*for CRC*/ - 4/*for a program_number+PID*/) {
      u_int16_t program_number = get2Bytes();
      u_int16_t pid = get2Bytes()&0x1FFF;

#ifdef DEBUG_CONTENTS
      fprintf(stderr, "\t\tprogram_number: %d; PID: 0x%04x\n", program_number, pid);
#endif
      if (program_number != 0x0000) {
	if (fPIDState[pid] == NULL) fPIDState[pid] = new PIDState_PMT(*this, pid, program_number);
      }
    }
  } while (0);

  // Skip (ignore) all remaining bytes in this packet (including the CRC):
  int numBytesLeft = numDataBytes - (curOffset() - startPos);
  if (numBytesLeft > 0) {
#ifdef DEBUG_CONTENTS
    fprintf(stderr, "\t\t+%d CRC and stuffing bytes\n", numBytesLeft);
#endif
    skipBytes(numBytesLeft);
  }
}


//########## PIDState_PAT implementation ##########

PIDState_PAT::PIDState_PAT(MPEG2TransportStreamParser& parser, u_int16_t pid)
  : PIDState(parser, pid, PAT) {
}

PIDState_PAT::~PIDState_PAT() {
}