mpeg2transportstreamfrompessource.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

	  u_int8_t extHighBit = (fPCRExtension&0x100)>>8;
	  *header++ = pcrHigh32Bits>>24;
	  *header++ = pcrHigh32Bits>>16;
	  *header++ = pcrHigh32Bits>>8;
	  *header++ = pcrHigh32Bits;
	  *header++ = (pcrLowBit<<7)|0x7E|extHighBit;
	  *header++ = (u_int8_t)fPCRExtension; // low 8 bits of extension
	}
      }
    }
    
    // Add any padding bytes:
    for (unsigned i = 0; i < numPaddingBytes; ++i) *header++ = 0xFF;

    // Finally, add the data bytes:
    memmove(header, &buffer[startPositionInBuffer], numDataBytes);
    startPositionInBuffer += numDataBytes;
  }
}

static u_int32_t calculateCRC(u_int8_t* data, unsigned dataLength); // forward

#define PAT_PID 0
#define OUR_PROGRAM_NUMBER 1
#define OUR_PROGRAM_MAP_PID 0x10

void MPEG2TransportStreamFromPESSource::deliverPATPacket() {
  // First, create a new buffer for the PAT packet:
  unsigned const patSize = TRANSPORT_PACKET_SIZE - 4; // allow for the 4-byte header
  unsigned char* patBuffer = new unsigned char[patSize];

  // and fill it in:
  unsigned char* pat = patBuffer;
  *pat++ = 0; // pointer_field
  *pat++ = 0; // table_id
  *pat++ = 0xB0; // section_syntax_indicator; 0; reserved, section_length (high)
  *pat++ = 13; // section_length (low)
  *pat++ = 0; *pat++ = 1; // transport_stream_id
  *pat++ = 0xC3; // reserved; version_number; current_next_indicator
  *pat++ = 0; // section_number
  *pat++ = 0; // last_section_number
  *pat++ = OUR_PROGRAM_NUMBER>>8; *pat++ = OUR_PROGRAM_NUMBER; // program_number
  *pat++ = 0xE0|(OUR_PROGRAM_MAP_PID>>8); // reserved; program_map_PID (high)
  *pat++ = OUR_PROGRAM_MAP_PID; // program_map_PID (low)
 
  // Compute the CRC from the bytes we currently have (not including "pointer_field"):
  u_int32_t crc = calculateCRC(patBuffer+1, pat - (patBuffer+1));
  *pat++ = crc>>24; *pat++ = crc>>16; *pat++ = crc>>8; *pat++ = crc;
  
  // Fill in the rest of the packet with padding bytes:
  while (pat < &patBuffer[patSize]) *pat++ = 0xFF;

  // Deliver the packet:
  unsigned startPosition = 0;
  deliverDataToClient(PAT_PID, patBuffer, patSize, startPosition);
  
  // Finally, remove the new buffer:
  delete[] patBuffer;
}

void MPEG2TransportStreamFromPESSource::deliverPMTPacket(Boolean hasChanged) {
  if (hasChanged) ++fProgramMapVersion;

  // First, create a new buffer for the PMT packet:
  unsigned const pmtSize = TRANSPORT_PACKET_SIZE - 4; // allow for the 4-byte header
  unsigned char* pmtBuffer = new unsigned char[pmtSize];

  // and fill it in:
  unsigned char* pmt = pmtBuffer;
  *pmt++ = 0; // pointer_field
  *pmt++ = 2; // table_id
  *pmt++ = 0xB0; // section_syntax_indicator; 0; reserved, section_length (high)
  unsigned char* section_lengthPtr = pmt; // save for later
  *pmt++ = 0; // section_length (low) (fill in later)
  *pmt++ = OUR_PROGRAM_NUMBER>>8; *pmt++ = OUR_PROGRAM_NUMBER; // program_number
  *pmt++ = 0xC1|((fProgramMapVersion&0x1F)<<1); // reserved; version_number; current_next_indicator
  *pmt++ = 0; // section_number
  *pmt++ = 0; // last_section_number
  *pmt++ = 0xE0; // reserved; PCR_PID (high)
  *pmt++ = fPCR_PID; // PCR_PID (low)
  *pmt++ = 0xF0; // reserved; program_info_length (high)
  *pmt++ = 0; // program_info_length (low)
  for (int pid = 0; pid < PID_TABLE_SIZE; ++pid) {
    if (fPIDState[pid].streamType != 0) { 
      // This PID gets recorded in the table
      *pmt++ = fPIDState[pid].streamType;
      *pmt++ = 0xE0; // reserved; elementary_pid (high)
      *pmt++ = pid; // elementary_pid (low)
      *pmt++ = 0xF0; // reserved; ES_info_length (high)
      *pmt++ = 0; // ES_info_length (low)
    }
  }
  unsigned section_length = pmt - (section_lengthPtr+1) + 4 /*for CRC*/;
  *section_lengthPtr = section_length;
 
  // Compute the CRC from the bytes we currently have (not including "pointer_field"):
  u_int32_t crc = calculateCRC(pmtBuffer+1, pmt - (pmtBuffer+1));
  *pmt++ = crc>>24; *pmt++ = crc>>16; *pmt++ = crc>>8; *pmt++ = crc;
  
  // Fill in the rest of the packet with padding bytes:
  while (pmt < &pmtBuffer[pmtSize]) *pmt++ = 0xFF;

  // Deliver the packet:
  unsigned startPosition = 0;
  deliverDataToClient(OUR_PROGRAM_MAP_PID, pmtBuffer, pmtSize, startPosition);
  
  // Finally, remove the new buffer:
  delete[] pmtBuffer;
}

void MPEG2TransportStreamFromPESSource::setProgramStreamMap(unsigned frameSize) {
  if (frameSize <= 16) return; // program_stream_map is too small to be useful
  if (frameSize > 0xFF) return; // program_stream_map is too large

  u_int16_t program_stream_map_length = (fInputBuffer[4]<<8) | fInputBuffer[5];
  if ((u_int16_t)frameSize > 6+program_stream_map_length) {
    frameSize = 6+program_stream_map_length;
  }
  
  u_int8_t versionByte = fInputBuffer[6];
  if ((versionByte&0x80) == 0) return; // "current_next_indicator" is not set
  fCurrentInputProgramMapVersion = versionByte&0x1F;

  u_int16_t program_stream_info_length = (fInputBuffer[8]<<8) | fInputBuffer[9];
  unsigned offset = 10 + program_stream_info_length; // skip over 'descriptors'

  u_int16_t elementary_stream_map_length
    = (fInputBuffer[offset]<<8) | fInputBuffer[offset+1];
  offset += 2;
  frameSize -= 4; // sizeof CRC_32
  if (frameSize > offset + elementary_stream_map_length) {
    frameSize = offset + elementary_stream_map_length;
  } 

  while (offset + 4 <= frameSize) {
    u_int8_t stream_type = fInputBuffer[offset];
    u_int8_t elementary_stream_id = fInputBuffer[offset+1];

    fPIDState[elementary_stream_id].streamType = stream_type;

    u_int16_t elementary_stream_info_length
      = (fInputBuffer[offset+2]<<8) | fInputBuffer[offset+3];
    offset += 4 + elementary_stream_info_length;
  }
}

static u_int32_t CRC32[256] = {
  0x00000000, 0x04c11db7, 0x09823b6e, 0x0d4326d9,
  0x130476dc, 0x17c56b6b, 0x1a864db2, 0x1e475005,
  0x2608edb8, 0x22c9f00f, 0x2f8ad6d6, 0x2b4bcb61,
  0x350c9b64, 0x31cd86d3, 0x3c8ea00a, 0x384fbdbd,
  0x4c11db70, 0x48d0c6c7, 0x4593e01e, 0x4152fda9,
  0x5f15adac, 0x5bd4b01b, 0x569796c2, 0x52568b75,
  0x6a1936c8, 0x6ed82b7f, 0x639b0da6, 0x675a1011,
  0x791d4014, 0x7ddc5da3, 0x709f7b7a, 0x745e66cd,
  0x9823b6e0, 0x9ce2ab57, 0x91a18d8e, 0x95609039,
  0x8b27c03c, 0x8fe6dd8b, 0x82a5fb52, 0x8664e6e5,
  0xbe2b5b58, 0xbaea46ef, 0xb7a96036, 0xb3687d81,
  0xad2f2d84, 0xa9ee3033, 0xa4ad16ea, 0xa06c0b5d,
  0xd4326d90, 0xd0f37027, 0xddb056fe, 0xd9714b49,
  0xc7361b4c, 0xc3f706fb, 0xceb42022, 0xca753d95,
  0xf23a8028, 0xf6fb9d9f, 0xfbb8bb46, 0xff79a6f1,
  0xe13ef6f4, 0xe5ffeb43, 0xe8bccd9a, 0xec7dd02d,
  0x34867077, 0x30476dc0, 0x3d044b19, 0x39c556ae,
  0x278206ab, 0x23431b1c, 0x2e003dc5, 0x2ac12072,
  0x128e9dcf, 0x164f8078, 0x1b0ca6a1, 0x1fcdbb16,
  0x018aeb13, 0x054bf6a4, 0x0808d07d, 0x0cc9cdca,
  0x7897ab07, 0x7c56b6b0, 0x71159069, 0x75d48dde,
  0x6b93dddb, 0x6f52c06c, 0x6211e6b5, 0x66d0fb02,
  0x5e9f46bf, 0x5a5e5b08, 0x571d7dd1, 0x53dc6066,
  0x4d9b3063, 0x495a2dd4, 0x44190b0d, 0x40d816ba,
  0xaca5c697, 0xa864db20, 0xa527fdf9, 0xa1e6e04e,
  0xbfa1b04b, 0xbb60adfc, 0xb6238b25, 0xb2e29692,
  0x8aad2b2f, 0x8e6c3698, 0x832f1041, 0x87ee0df6,
  0x99a95df3, 0x9d684044, 0x902b669d, 0x94ea7b2a,
  0xe0b41de7, 0xe4750050, 0xe9362689, 0xedf73b3e,
  0xf3b06b3b, 0xf771768c, 0xfa325055, 0xfef34de2,
  0xc6bcf05f, 0xc27dede8, 0xcf3ecb31, 0xcbffd686,
  0xd5b88683, 0xd1799b34, 0xdc3abded, 0xd8fba05a,
  0x690ce0ee, 0x6dcdfd59, 0x608edb80, 0x644fc637,
  0x7a089632, 0x7ec98b85, 0x738aad5c, 0x774bb0eb,
  0x4f040d56, 0x4bc510e1, 0x46863638, 0x42472b8f,
  0x5c007b8a, 0x58c1663d, 0x558240e4, 0x51435d53,
  0x251d3b9e, 0x21dc2629, 0x2c9f00f0, 0x285e1d47,
  0x36194d42, 0x32d850f5, 0x3f9b762c, 0x3b5a6b9b,
  0x0315d626, 0x07d4cb91, 0x0a97ed48, 0x0e56f0ff,
  0x1011a0fa, 0x14d0bd4d, 0x19939b94, 0x1d528623,
  0xf12f560e, 0xf5ee4bb9, 0xf8ad6d60, 0xfc6c70d7,
  0xe22b20d2, 0xe6ea3d65, 0xeba91bbc, 0xef68060b,
  0xd727bbb6, 0xd3e6a601, 0xdea580d8, 0xda649d6f,
  0xc423cd6a, 0xc0e2d0dd, 0xcda1f604, 0xc960ebb3,
  0xbd3e8d7e, 0xb9ff90c9, 0xb4bcb610, 0xb07daba7,
  0xae3afba2, 0xaafbe615, 0xa7b8c0cc, 0xa379dd7b,
  0x9b3660c6, 0x9ff77d71, 0x92b45ba8, 0x9675461f,
  0x8832161a, 0x8cf30bad, 0x81b02d74, 0x857130c3,
  0x5d8a9099, 0x594b8d2e, 0x5408abf7, 0x50c9b640,
  0x4e8ee645, 0x4a4ffbf2, 0x470cdd2b, 0x43cdc09c,
  0x7b827d21, 0x7f436096, 0x7200464f, 0x76c15bf8,
  0x68860bfd, 0x6c47164a, 0x61043093, 0x65c52d24,
  0x119b4be9, 0x155a565e, 0x18197087, 0x1cd86d30,
  0x029f3d35, 0x065e2082, 0x0b1d065b, 0x0fdc1bec,
  0x3793a651, 0x3352bbe6, 0x3e119d3f, 0x3ad08088,
  0x2497d08d, 0x2056cd3a, 0x2d15ebe3, 0x29d4f654,
  0xc5a92679, 0xc1683bce, 0xcc2b1d17, 0xc8ea00a0,
  0xd6ad50a5, 0xd26c4d12, 0xdf2f6bcb, 0xdbee767c,
  0xe3a1cbc1, 0xe760d676, 0xea23f0af, 0xeee2ed18,
  0xf0a5bd1d, 0xf464a0aa, 0xf9278673, 0xfde69bc4,
  0x89b8fd09, 0x8d79e0be, 0x803ac667, 0x84fbdbd0,
  0x9abc8bd5, 0x9e7d9662, 0x933eb0bb, 0x97ffad0c,
  0xafb010b1, 0xab710d06, 0xa6322bdf, 0xa2f33668,
  0xbcb4666d, 0xb8757bda, 0xb5365d03, 0xb1f740b4
};

static u_int32_t calculateCRC(u_int8_t* data, unsigned dataLength) {
  u_int32_t crc = 0xFFFFFFFF;

  while (dataLength-- > 0) {
    crc = (crc<<8) ^ CRC32[(crc>>24) ^ (u_int32_t)(*data++)];
  }

  return crc;
}