atsc_mgt.c

Dvbstreamer 用在解析MPTS的部分内容

    }
  }

  return p_table;
}


/*****************************************************************************
 * dvbpsi_atsc_MGTTableAddDescriptor
 *****************************************************************************
 * Add a descriptor in the MGT table description.
 *****************************************************************************/
dvbpsi_descriptor_t *dvbpsi_atsc_MGTTableAddDescriptor(
                                               dvbpsi_atsc_mgt_table_t *p_table,
                                               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_table->p_first_descriptor == NULL)
    {
      p_table->p_first_descriptor = p_descriptor;
    }
    else
    {
      dvbpsi_descriptor_t * p_last_descriptor = p_table->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_atsc_GatherMGTSections
 *****************************************************************************
 * Callback for the subtable demultiplexor.
 *****************************************************************************/
void dvbpsi_atsc_GatherMGTSections(dvbpsi_decoder_t * p_psi_decoder,
                              void * p_private_decoder,
                              dvbpsi_psi_section_t * p_section)
{
  dvbpsi_atsc_mgt_decoder_t * p_mgt_decoder
                        = (dvbpsi_atsc_mgt_decoder_t*)p_private_decoder;
  int b_append = 1;
  int b_reinit = 0;
  unsigned int i;

  DVBPSI_DEBUG_ARG("MGT decoder",
                   "Table version %2d, " "i_table_id %2d, " "i_extension %5d, "
                   "section %3d up to %3d, " "current %1d",
                   p_section->i_version, p_section->i_table_id,
                   p_section->i_extension,
                   p_section->i_number, p_section->i_last_number,
                   p_section->b_current_next);

  if(!p_section->b_syntax_indicator)
  {
    /* Invalid section_syntax_indicator */
    DVBPSI_ERROR("MGT decoder",
                 "invalid section (section_syntax_indicator == 0)");
    b_append = 0;
  }

  /* Now if b_append is true then we have a valid MGT section */
  if(b_append)
  {
    /* TS discontinuity check */
    if(p_psi_decoder->b_discontinuity)
    {
      b_reinit = 1;
      p_psi_decoder->b_discontinuity = 0;
    }
    else
    {
      /* Perform a few sanity checks */
      if(p_mgt_decoder->p_building_mgt)
      {
        if(p_mgt_decoder->p_building_mgt->i_version
                                                != p_section->i_version)
        {
          /* version_number */
          DVBPSI_ERROR("MGT decoder",
                       "'version_number' differs"
                       " whereas no discontinuity has occured");
          b_reinit = 1;
        }
        else if(p_mgt_decoder->i_last_section_number !=
                                                p_section->i_last_number)
        {
          /* last_section_number */
          DVBPSI_ERROR("MGT decoder",
                       "'last_section_number' differs"
                       " whereas no discontinuity has occured");
          b_reinit = 1;
        }
      }
      else
      {
        if(    (p_mgt_decoder->b_current_valid)
            && (p_mgt_decoder->current_mgt.i_version == p_section->i_version))
        {
          /* Signal a new MGT if the previous one wasn't active */
          if(    (!p_mgt_decoder->current_mgt.b_current_next)
              && (p_section->b_current_next))
          {
            dvbpsi_atsc_mgt_t * p_mgt = (dvbpsi_atsc_mgt_t*)ObjectCreateType(dvbpsi_atsc_mgt_t);

            p_mgt_decoder->current_mgt.b_current_next = 1;
            *p_mgt = p_mgt_decoder->current_mgt;
            p_mgt_decoder->pf_callback(p_mgt_decoder->p_cb_data, p_mgt);
          }

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

  /* Reinit the decoder if wanted */
  if(b_reinit)
  {
    /* Force redecoding */
    p_mgt_decoder->b_current_valid = 0;
    /* Free structures */
    if(p_mgt_decoder->p_building_mgt)
    {
      ObjectRefDec(p_mgt_decoder->p_building_mgt);
      p_mgt_decoder->p_building_mgt = NULL;
    }
    /* Clear the section array */
    for(i = 0; i <= 255; i++)
    {
      if(p_mgt_decoder->ap_sections[i] != NULL)
      {
        dvbpsi_ReleasePSISections(p_psi_decoder, p_mgt_decoder->ap_sections[i]);
        p_mgt_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_mgt_decoder->p_building_mgt)
    {
      dvbpsi_atsc_NewMGT(p_mgt_decoder->p_building_mgt,
                     p_section->i_version,
                     p_section->b_current_next,
                     p_section->p_payload_start[0]);
      p_mgt_decoder->i_last_section_number = p_section->i_last_number;
    }

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

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

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

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


/*****************************************************************************
 * dvbpsi_atsc_DecodeMGTSection
 *****************************************************************************
 * MGT decoder.
 *****************************************************************************/
void dvbpsi_atsc_DecodeMGTSections(dvbpsi_atsc_mgt_t* p_mgt,
                              dvbpsi_psi_section_t* p_section)
{
  uint8_t *p_byte, *p_end;

  while(p_section)
  {
    uint16_t i_tables_defined = (p_section->p_payload_start[1] << 8) | 
                                 p_section->p_payload_start[2];
    uint16_t i_table_count = 0;
    uint16_t i_length = 0;
    
    for(p_byte = p_section->p_payload_start + 3; 
        ((p_byte + 6) < p_section->p_payload_end) && (i_table_count < i_tables_defined); 
        i_table_count ++)
    {
        dvbpsi_atsc_mgt_table_t* p_table;
        uint16_t i_type = ((uint16_t)(p_byte[0] << 8)) | p_byte[1];
        uint16_t i_pid  = ((uint16_t)(p_byte[2] & 0x1f) << 8) | p_byte[3];                                           
        uint8_t i_version = (uint8_t)(p_byte[4] & 0x1f);
        uint32_t i_number_bytes = ((uint32_t) p_byte[5] << 24) |
                                  ((uint32_t) p_byte[6] << 16) |
                                  ((uint32_t) p_byte[7] <<  8) |
                                  p_byte[8];
        i_length = ((uint16_t)(p_byte[9] & 0xf) <<8) | p_byte[10];

        p_table = dvbpsi_atsc_MGTAddTable(p_mgt, i_type, i_pid, i_version, i_number_bytes);

        /* Table descriptors */
        p_byte += 11;
        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_length = p_byte[1];
        if(i_length + 2 <= p_end - p_byte)
          dvbpsi_atsc_MGTTableAddDescriptor(p_table, i_tag, i_length, p_byte + 2);
        p_byte += 2 + i_length;
        }
    }

    /* Table descriptors */
    i_length = ((uint16_t)(p_byte[0] & 0xf) <<8) | p_byte[1];
    p_byte += 2;
    p_end = p_byte + i_length;

    while(p_byte + 2 <= p_end)
    {
        uint8_t i_tag = p_byte[0];
        uint8_t i_length = p_byte[1];
        if(i_length + 2 <= p_end - p_byte)
          dvbpsi_atsc_MGTAddDescriptor(p_mgt, i_tag, i_length, p_byte + 2);
        p_byte += 2 + i_length;
    }
    p_section = p_section->p_next;
  }
}