Parser::parse_ipco( int $num_remaining_bytes ): AvifinfoStatus

Source

private function parse_ipco( $num_remaining_bytes ) {
  $box_index = 1; // 1-based index. Used for iterating over properties.
  do {
    $box    = new Box();
    $status = $box->parse( $this->handle, $this->num_parsed_boxes, $num_remaining_bytes );
    if ( $status != FOUND ) {
      return $status;
    }

    if ( $box->type == 'ispe' ) {
      // See ISO/IEC 23008-12:2017(E) 6.5.3.2
      if ( $box->content_size < 8 ) {
        return INVALID;
      }
      if ( !( $data = read( $this->handle, 8 ) ) ) {
        return TRUNCATED;
      }
      $width  = read_big_endian( substr( $data, 0, 4 ), 4 );
      $height = read_big_endian( substr( $data, 4, 4 ), 4 );
      if ( $width == 0 || $height == 0 ) {
        return INVALID;
      }
      if ( count( $this->features->dim_props ) <= MAX_FEATURES &&
           $box_index <= MAX_VALUE ) {
        $dim_prop_count = count( $this->features->dim_props );
        $this->features->dim_props[$dim_prop_count]                 = new Dim_Prop();
        $this->features->dim_props[$dim_prop_count]->property_index = $box_index;
        $this->features->dim_props[$dim_prop_count]->width          = $width;
        $this->features->dim_props[$dim_prop_count]->height         = $height;
      } else {
        $this->data_was_skipped = true;
      }
      if ( !skip( $this->handle, $box->content_size - 8 ) ) {
        return TRUNCATED;
      }
    } else if ( $box->type == 'pixi' ) {
      // See ISO/IEC 23008-12:2017(E) 6.5.6.2
      if ( $box->content_size < 1 ) {
        return INVALID;
      }
      if ( !( $data = read( $this->handle, 1 ) ) ) {
        return TRUNCATED;
      }
      $num_channels = read_big_endian( $data, 1 );
      if ( $num_channels < 1 ) {
        return INVALID;
      }
      if ( $box->content_size < 1 + $num_channels ) {
        return INVALID;
      }
      if ( !( $data = read( $this->handle, 1 ) ) ) {
        return TRUNCATED;
      }
      $bit_depth = read_big_endian( $data, 1 );
      if ( $bit_depth < 1 ) {
        return INVALID;
      }
      for ( $i = 1; $i < $num_channels; ++$i ) {
        if ( !( $data = read( $this->handle, 1 ) ) ) {
          return TRUNCATED;
        }
        // Bit depth should be the same for all channels.
        if ( read_big_endian( $data, 1 ) != $bit_depth ) {
          return INVALID;
        }
        if ( $i > 32 ) {
          return ABORTED; // Be reasonable.
        }
      }
      if ( count( $this->features->chan_props ) <= MAX_FEATURES &&
           $box_index <= MAX_VALUE && $bit_depth <= MAX_VALUE &&
           $num_channels <= MAX_VALUE ) {
        $chan_prop_count = count( $this->features->chan_props );
        $this->features->chan_props[$chan_prop_count]                 = new Chan_Prop();
        $this->features->chan_props[$chan_prop_count]->property_index = $box_index;
        $this->features->chan_props[$chan_prop_count]->bit_depth      = $bit_depth;
        $this->features->chan_props[$chan_prop_count]->num_channels   = $num_channels;
      } else {
        $this->data_was_skipped = true;
      }
      if ( !skip( $this->handle, $box->content_size - ( 1 + $num_channels ) ) ) {
        return TRUNCATED;
      }
    } else if ( $box->type == 'av1C' ) {
      // See AV1 Codec ISO Media File Format Binding 2.3.1
      // at https://aomediacodec.github.io/av1-isobmff/#av1c
      // Only parse the necessary third byte. Assume that the others are valid.
      if ( $box->content_size < 3 ) {
        return INVALID;
      }
      if ( !( $data = read( $this->handle, 3 ) ) ) {
        return TRUNCATED;
      }
      $byte          = read_big_endian( substr( $data, 2, 1 ), 1 );
      $high_bitdepth = ( $byte & 0x40 ) != 0;
      $twelve_bit    = ( $byte & 0x20 ) != 0;
      $monochrome    = ( $byte & 0x10 ) != 0;
      if ( $twelve_bit && !$high_bitdepth ) {
          return INVALID;
      }
      if ( count( $this->features->chan_props ) <= MAX_FEATURES &&
           $box_index <= MAX_VALUE ) {
        $chan_prop_count = count( $this->features->chan_props );
        $this->features->chan_props[$chan_prop_count]                 = new Chan_Prop();
        $this->features->chan_props[$chan_prop_count]->property_index = $box_index;
        $this->features->chan_props[$chan_prop_count]->bit_depth      =
            $high_bitdepth ? $twelve_bit ? 12 : 10 : 8;
        $this->features->chan_props[$chan_prop_count]->num_channels   = $monochrome ? 1 : 3;
      } else {
        $this->data_was_skipped = true;
      }
      if ( !skip( $this->handle, $box->content_size - 3 ) ) {
        return TRUNCATED;
      }
    } else if ( $box->type == 'auxC' ) {
      // See AV1 Image File Format (AVIF) 4
      // at https://aomediacodec.github.io/av1-avif/#auxiliary-images
      $kAlphaStr       = "urn:mpeg:mpegB:cicp:systems:auxiliary:alpha\0";
      $kAlphaStrLength = 44; // Includes terminating character.
      if ( $box->content_size >= $kAlphaStrLength ) {
        if ( !( $data = read( $this->handle, $kAlphaStrLength ) ) ) {
          return TRUNCATED;
        }
        if ( substr( $data, 0, $kAlphaStrLength ) == $kAlphaStr ) {
          // Note: It is unlikely but it is possible that this alpha plane does
          //       not belong to the primary item or a tile. Ignore this issue.
          $this->features->has_alpha = true;
        }
        if ( !skip( $this->handle, $box->content_size - $kAlphaStrLength ) ) {
          return TRUNCATED;
        }
      } else {
        if ( !skip( $this->handle, $box->content_size ) ) {
          return TRUNCATED;
        }
      }
    } else {
      if ( !skip( $this->handle, $box->content_size ) ) {
        return TRUNCATED;
      }
    }
    ++$box_index;
    $num_remaining_bytes -= $box->size;
  } while ( $num_remaining_bytes > 0 );
  return NOT_FOUND;
}

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