GB28181的PS流分析: 封装 / 分包发送 / 接收组包 / 解析

ps payload SPS 00 00 00 01 67 ...

ps payload PPS 00 00 00 01 68 ...

ps payload I   00 00 00 01 65 ...

ps payload P   00 00 00 01 61/41 ...

while ((pack = sess.GetNextPacket()) != NULL) { 
  loaddata = pack->GetPayloadData(); 
  len = pack->GetPayloadLength(); /* payload type: ps */
  if(pack->GetPayloadType() == 96) { /*the last packet*/
      if(pack->HasMarker()) {
        if(pos + len < PS_BUFFER_SIZE){ 
          memcpy(&buff[pos],loaddata,len); 
          printf("!!! GetPayload len = %ld !!!! \n ",pos+len); 
          size_t r = ps_demuxer_input(ps, buff, pos+len); 
          pos = 0; 
          lasttime = nowtime; 
        } 
      } else { 
      if(pos + len < PS_BUFFER_SIZE){ 
        memcpy(&buff[pos],loaddata,len); 
        pos = pos + len; 
      } 
    } 
  } else { 
    printf("!!! GetPayloadType = %d !!!! \n ",pack->GetPayloadType()); 
  } sess.DeletePacket(pack); 
}

/* SPS frame 00 00 00 01 67 PPS frame 00 00 00 01 68 I frame 00 00 00 01 65 P slice 00 00 00 01 41/61 */
if(FindStartCode(p)) {
  data_t d; 
  if(rb_numitems(task->buffer) < DATA_ITEM_NMAX){ 
    if(task->pos < ITEM_BUFFER_SIZE) {
      memcpy(d.buf,task->buf, task->pos); 
      d.size = task->pos; d.type = H264; 
      rb_put(task->buffer, &d); 
      fflush(stdout); 
    } 
  } 
  task->pos = 0; 
  if((task->pos + bytes) < TASK_BUFFER_SIZE){ 
    memcpy(&(task->buf[task->pos]),p,bytes); 
    task->pos = task->pos + bytes; 
  } 
} else { 
  if((task->pos + bytes) < TASK_BUFFER_SIZE){
    memcpy(&(task->buf[task->pos]),p,bytes); 
    task->pos = task->pos + bytes;
  } 
}

data_t d; 
if (rb_numitems(task->buffer) < DATA_ITEM_NMAX) { 
  if(bytes < ITEM_BUFFER_SIZE){ 
    memcpy(d.buf, p, bytes); 
    d.size = bytes; 
    d.type = G711A; 
    rb_put(task->buffer, &d); 
    fflush(stdout); 
  } 
}

Boolean H264VideoRTPSource::processSpecialHeader(BufferedPacket* packet, unsigned& resultSpecialHeaderSize) { 
  unsigned char* headerStart = packet->data(); 
  unsigned packetSize = packet->dataSize(); 
  unsigned numBytesToSkip; // Check the 'nal_unit_type' for special 'aggregation' or 'fragmentation' packets:
  if (packetSize < 1) 
    return False; 
    fCurPacketNALUnitType = (headerStart[0]&0x1F); 
    switch (fCurPacketNALUnitType) { 
    case 24: { // STAP-A
      numBytesToSkip = 1; // discard the type byte
      break; } 
    case 25:
    case 26: 
    case 27: { // STAP-B, MTAP16, or MTAP24
      numBytesToSkip = 3; // discard the type byte, and the initial DON
    break; 
    } 
    case 28: 
    case 29: { // // FU-A or FU-B // For these NALUs, the first two bytes are the FU indicator and the FU header. // If the start bit is set, we reconstruct the original NAL header into byte 1:
      if (packetSize < 2) 
        return False; 
      unsigned char startBit = headerStart[1]&0x80; 
      unsigned char endBit = headerStart[1]&0x40; 
      if (startBit) { 
        fCurrentPacketBeginsFrame = True; 
        headerStart[1] = (headerStart[0]&0xE0)|(headerStart[1]&0x1F); 
        numBytesToSkip = 1; 
        } else { // The start bit is not set, so we skip both the FU indicator and header:
        
        fCurrentPacketBeginsFrame = False; 
        numBytesToSkip = 2; 
      } 
    fCurrentPacketCompletesFrame = (endBit != 0);
    break; 
  } 
  default: { // This packet contains one complete NAL unit:

  fCurrentPacketBeginsFrame = fCurrentPacketCompletesFrame = True; 
  numBytesToSkip = 0; 
  break; 
  } 
} resultSpecialHeaderSize = numBytesToSkip; return True; }

H264VideoRTPSink* H264VideoRTPSink ::createNew(UsageEnvironment& env, Groupsock* RTPgs, unsigned char rtpPayloadFormat, char const* sPropParameterSetsStr) {
    u_int8_t* sps = NULL; 
    unsigned spsSize = 0; 
    u_int8_t* pps = NULL; 
    unsigned ppsSize = 0; 
    unsigned numSPropRecords; 
    SPropRecord* sPropRecords = parseSPropParameterSets(sPropParameterSetsStr, numSPropRecords); 
    for (unsigned i = 0; i < numSPropRecords; ++i) { 
      if (sPropRecords[i].sPropLength == 0)
        continue; // bad data
      u_int8_t nal_unit_type = (sPropRecords[i].sPropBytes[0])&0x1F;
      if (nal_unit_type == 7/*SPS*/) { 
        sps = sPropRecords[i].sPropBytes; 
        spsSize = sPropRecords[i].sPropLength; 
      } else if (nal_unit_type == 8/*PPS*/) {
        pps = sPropRecords[i].sPropBytes; 
        ppsSize = sPropRecords[i].sPropLength; 
      } 
    } 
    H264VideoRTPSink* result = new H264VideoRTPSink(env, RTPgs, rtpPayloadFormat, sps, spsSize, pps, ppsSize); 
    delete[] sPropRecords; 
    return result; 
}