nit.c

Dvbstreamer 用在解析MPTS的部分内容

          DVBPSI_ERROR("NIT decoder",
                       "'version_number' differs"
                       " whereas no discontinuity has occured");
          b_reinit = 1;
        }
        else if(p_nit_decoder->i_last_section_number !=
                                                p_section->i_last_number)
        {
          /* last_section_number */
          DVBPSI_ERROR("NIT decoder",
                       "'last_section_number' differs"
                       " whereas no discontinuity has occured");
          b_reinit = 1;
        }
      }
      else
      {
        if(    (p_nit_decoder->b_current_valid)
            && (p_nit_decoder->current_nit.i_version == p_section->i_version))
        {
          /* Signal a new NIT if the previous one wasn't active */
          if(    (!p_nit_decoder->current_nit.b_current_next)
              && (p_section->b_current_next))
          {
            dvbpsi_nit_t * p_nit = (dvbpsi_nit_t*)ObjectCreateType(dvbpsi_nit_t);

            p_nit_decoder->current_nit.b_current_next = 1;
            *p_nit = p_nit_decoder->current_nit;
            p_nit_decoder->pf_callback(p_nit_decoder->p_cb_data, p_nit);
          }

          /* Don't decode since this version is already decoded */
          b_append = 0;
        }
      }
    }
  }

  /* Reinit the decoder if wanted */
  if(b_reinit)
  {
    /* Force redecoding */
    p_nit_decoder->b_current_valid = 0;
    /* Free structures */
    if(p_nit_decoder->p_building_nit)
    {
      ObjectRefDec(p_nit_decoder->p_building_nit);
      p_nit_decoder->p_building_nit = NULL;
    }
    /* Clear the section array */
    for(i = 0; i <= 255; i++)
    {
      if(p_nit_decoder->ap_sections[i] != NULL)
      {
        dvbpsi_ReleasePSISections(p_psi_decoder, p_nit_decoder->ap_sections[i]);
        p_nit_decoder->ap_sections[i] = NULL;
      }
    }
  }

  /* Append the section to the list if wanted */
  if(b_append)
  {
    int b_complete;

    /* Initialize the structures if it's the first section received */
    if(!p_nit_decoder->p_building_nit)
    {
      dvbpsi_NewNIT(p_nit_decoder->p_building_nit,
                     p_section->i_extension,
                     p_section->i_version,
                     p_section->b_current_next);
      p_nit_decoder->i_last_section_number = p_section->i_last_number;
    }

    /* Fill the section array */
    if(p_nit_decoder->ap_sections[p_section->i_number] != NULL)
    {
      DVBPSI_ERROR_ARG("NIT decoder", "NIT decoder: overwrite section number %d",
                       p_section->i_number);
      dvbpsi_ReleasePSISections(p_psi_decoder, p_nit_decoder->ap_sections[p_section->i_number]);
    }
    p_nit_decoder->ap_sections[p_section->i_number] = p_section;

    /* Check if we have all the sections */
    b_complete = 0;
    for(i = 0; i <= p_nit_decoder->i_last_section_number; i++)
    {
      if(!p_nit_decoder->ap_sections[i])
        break;

      if(i == p_nit_decoder->i_last_section_number)
        b_complete = 1;
    }

    if(b_complete)
    {
      /* Save the current information */
      p_nit_decoder->current_nit = *p_nit_decoder->p_building_nit;
      p_nit_decoder->b_current_valid = 1;
      /* Chain the sections */
      if(p_nit_decoder->i_last_section_number)
      {
        for(i = 0; i <= p_nit_decoder->i_last_section_number - 1; i++)
          p_nit_decoder->ap_sections[i]->p_next =
                                        p_nit_decoder->ap_sections[i + 1];
      }
      /* Decode the sections */
      dvbpsi_DecodeNITSections(p_nit_decoder->p_building_nit,
                               p_nit_decoder->ap_sections[0]);
      /* Delete the sections */
      dvbpsi_ReleasePSISections(p_psi_decoder, p_nit_decoder->ap_sections[0]);
      /* signal the new NIT */
      p_nit_decoder->pf_callback(p_nit_decoder->p_cb_data,
                                 p_nit_decoder->p_building_nit);
      /* Reinitialize the structures */
      p_nit_decoder->p_building_nit = NULL;
      for(i = 0; i <= p_nit_decoder->i_last_section_number; i++)
        p_nit_decoder->ap_sections[i] = NULL;
    }
  }
  else
  {
    dvbpsi_ReleasePSISections(p_psi_decoder, p_section);
  }
}


/*****************************************************************************
 * dvbpsi_DecodeNITSection
 *****************************************************************************
 * NIT decoder.
 *****************************************************************************/
void dvbpsi_DecodeNITSections(dvbpsi_nit_t* p_nit,
                              dvbpsi_psi_section_t* p_section)
{
  uint8_t *p_byte, *p_end;
  uint8_t *p_ts_end;
  uint16_t i_ts_length;

  while(p_section)
  {
    for(p_byte = p_section->p_payload_start;
        p_byte + 4 < p_section->p_payload_end;)
    {
      uint16_t i_length = ((uint16_t)(p_byte[0] & 0xf) <<8) | p_byte[1];
      /* network descriptors */
      p_byte += 2;
      p_end = p_byte + i_length;
      if( p_end > p_section->p_payload_end ) break;

      while(p_byte + 2 <= p_end)
      {
        uint8_t i_tag = p_byte[0];
        uint8_t i_desc_length = p_byte[1];
        if(i_desc_length + 2 <= p_end - p_byte)
          dvbpsi_NITAddDescriptor(p_nit, i_tag, i_desc_length, p_byte + 2);
        p_byte += 2 + i_desc_length;
      }

      i_ts_length = ((uint16_t)(p_byte[0] & 0xf) <<8) | p_byte[1];
      p_byte += 2;
      p_ts_end = p_byte + i_ts_length;
      if( p_ts_end > p_section->p_payload_end ) break;

      while(p_byte + 2 <= p_ts_end)
      {
          uint16_t i_ts_id = ((uint16_t)p_byte[0]<<8) | p_byte[1];
          uint16_t i_original_network_id = ((uint16_t)p_byte[2]<<8) | p_byte[3];
          dvbpsi_nit_transport_t *p_transport = dvbpsi_NITAddTransport(p_nit, i_ts_id, i_original_network_id);
          i_length = ((uint16_t)(p_byte[4] & 0xf) <<8) | p_byte[5];
          p_byte += 6;

          p_end = p_byte + i_length;
          if( p_end > p_section->p_payload_end ) break;

          while(p_byte + 2 <= p_end)
          {
            uint8_t i_tag = p_byte[0];
            uint8_t i_desc_length = p_byte[1];
            if(i_desc_length + 2 <= p_end - p_byte)
              dvbpsi_NITTransportAddDescriptor(p_transport, i_tag, i_desc_length, p_byte + 2);
            p_byte += 2 + i_desc_length;
          }
      }
    }

    p_section = p_section->p_next;
  }
}



/*****************************************************************************
 * dvbpsi_NITAddDescriptor
 *****************************************************************************
 * Add a descriptor in the NIT description.
 *****************************************************************************/
dvbpsi_descriptor_t *dvbpsi_NITAddDescriptor(
                                               dvbpsi_nit_t *p_nit,
                                               uint8_t i_tag, uint8_t i_length,
                                               uint8_t *p_data)
{
  dvbpsi_descriptor_t * p_descriptor
                        = dvbpsi_NewDescriptor(i_tag, i_length, p_data);

  if(p_descriptor)
  {
    if(p_nit->p_first_descriptor == NULL)
    {
      p_nit->p_first_descriptor = p_descriptor;
    }
    else
    {
      dvbpsi_descriptor_t * p_last_descriptor = p_nit->p_first_descriptor;
      while(p_last_descriptor->p_next != NULL)
        p_last_descriptor = p_last_descriptor->p_next;
      p_last_descriptor->p_next = p_descriptor;
    }
  }

  return p_descriptor;
}


/*****************************************************************************
 * dvbpsi_NITAddTransport
 *****************************************************************************
 * Add a transport description at the end of the NIT.
 *****************************************************************************/
dvbpsi_nit_transport_t *dvbpsi_NITAddTransport(dvbpsi_nit_t* p_nit,
                                           uint16_t i_ts_id,
                                           uint16_t i_original_network_id)
{
  dvbpsi_nit_transport_t * p_transport
                = (dvbpsi_nit_transport_t*)malloc(sizeof(dvbpsi_nit_transport_t));

  if(p_transport)
  {
    p_transport->i_ts_id = i_ts_id;
    p_transport->i_original_network_id = i_original_network_id;
    p_transport->p_first_descriptor = NULL;
    p_transport->p_next = NULL;
    if(p_nit->p_first_transport == NULL)
    {
      p_nit->p_first_transport = p_transport;
    }
    else
    {
      dvbpsi_nit_transport_t * p_last_transport = p_nit->p_first_transport;
      while(p_last_transport->p_next != NULL)
        p_last_transport = p_last_transport->p_next;
      p_last_transport->p_next = p_transport;
    }
  }

  return p_transport;
}


/*****************************************************************************
 * dvbpsi_NITTransportAddDescriptor
 *****************************************************************************
 * Add a descriptor in the NIT transport description.
 *****************************************************************************/
dvbpsi_descriptor_t *dvbpsi_NITTransportAddDescriptor(
                                               dvbpsi_nit_transport_t *p_transport,
                                               uint8_t i_tag, uint8_t i_length,
                                               uint8_t *p_data)
{
  dvbpsi_descriptor_t * p_descriptor
                        = dvbpsi_NewDescriptor(i_tag, i_length, p_data);

  if(p_descriptor)
  {
    if(p_transport->p_first_descriptor == NULL)
    {
      p_transport->p_first_descriptor = p_descriptor;
    }
    else
    {
      dvbpsi_descriptor_t * p_last_descriptor = p_transport->p_first_descriptor;
      while(p_last_descriptor->p_next != NULL)
        p_last_descriptor = p_last_descriptor->p_next;
      p_last_descriptor->p_next = p_descriptor;
    }
  }

  return p_descriptor;
}