Parser::parse_meta( int $num_remaining_bytes ): AvifinfoStatus

In this article

This function’s access is marked private. This means it is not intended for use by plugin or theme developers, only in other core functions. It is listed here for completeness.

Parses a “meta” box.

Description

It looks for the primary item ID in the "pitm" box and recurses into other boxes to find its features.

Parameters

$handleAvifinfostreamrequired
The resource the box will be parsed from.
$num_remaining_bytesintrequired
The number of bytes that should be available from the resource.

Return

AvifinfoStatus FOUND on success or an error on failure.

Source

private function parse_meta( $num_remaining_bytes ) {
  do {
    $box    = new Box();
    $status = $box->parse( $this->handle, $this->num_parsed_boxes, $num_remaining_bytes );
    if ( $status != FOUND ) {
      return $status;
    }

    if ( $box->type == 'pitm' ) {
      // See ISO/IEC 14496-12:2015(E) 8.11.4.2
      $num_bytes_per_id = ( $box->version == 0 ) ? 2 : 4;
      if ( $num_bytes_per_id > $num_remaining_bytes ) {
        return INVALID;
      }
      if ( !( $data = read( $this->handle, $num_bytes_per_id ) ) ) {
        return TRUNCATED;
      }
      $primary_item_id = read_big_endian( $data, $num_bytes_per_id );
      if ( $primary_item_id > MAX_VALUE ) {
        return ABORTED;
      }
      $this->features->has_primary_item = true;
      $this->features->primary_item_id  = $primary_item_id;
      if ( !skip( $this->handle, $box->content_size - $num_bytes_per_id ) ) {
        return TRUNCATED;
      }
    } else if ( $box->type == 'iprp' ) {
      $status = $this->parse_iprp( $box->content_size );
      if ( $status != NOT_FOUND ) {
        return $status;
      }
    } else if ( $box->type == 'iref' ) {
      $status = $this->parse_iref( $box->content_size );
      if ( $status != NOT_FOUND ) {
        return $status;
      }
    } else {
      if ( !skip( $this->handle, $box->content_size ) ) {
        return TRUNCATED;
      }
    }
    $num_remaining_bytes -= $box->size;
  } while ( $num_remaining_bytes != 0 );
  // According to ISO/IEC 14496-12:2012(E) 8.11.1.1 there is at most one "meta".
  return INVALID;
}

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