Parser

315class Parser {316  private $handle; // Input stream.317  private $num_parsed_boxes = 0;318  private $data_was_skipped = false;319  public $features;320 321  function __construct( $handle ) {322    $this->handle   = $handle;323    $this->features = new Features();324  }325 326  /**327   * Parses an "ipco" box.328   *329   * "ispe" is used for width and height, "pixi" and "av1C" are used for bit depth330   * and number of channels, and "auxC" is used for alpha.331   *332   * @param stream  $handle              The resource the box will be parsed from.333   * @param int     $num_remaining_bytes The number of bytes that should be available from the resource.334   * @return Status                      FOUND on success or an error on failure.335   */336  private function parse_ipco( $num_remaining_bytes ) {337    $box_index = 1; // 1-based index. Used for iterating over properties.338    do {339      $box    = new Box();340      $status = $box->parse( $this->handle, $this->num_parsed_boxes, $num_remaining_bytes );341      if ( $status != FOUND ) {342        return $status;343      }344 345      if ( $box->type == 'ispe' ) {346        // See ISO/IEC 23008-12:2017(E) 6.5.3.2347        if ( $box->content_size < 8 ) {348          return INVALID;349        }350        if ( !( $data = read( $this->handle, 8 ) ) ) {351          return TRUNCATED;352        }353        $width  = read_big_endian( substr( $data, 0, 4 ), 4 );354        $height = read_big_endian( substr( $data, 4, 4 ), 4 );355        if ( $width == 0 || $height == 0 ) {356          return INVALID;357        }358        if ( count( $this->features->dim_props ) <= MAX_FEATURES &&359             $box_index <= MAX_VALUE ) {360          $dim_prop_count = count( $this->features->dim_props );361          $this->features->dim_props[$dim_prop_count]                 = new Dim_Prop();362          $this->features->dim_props[$dim_prop_count]->property_index = $box_index;363          $this->features->dim_props[$dim_prop_count]->width          = $width;364          $this->features->dim_props[$dim_prop_count]->height         = $height;365        } else {366          $this->data_was_skipped = true;367        }368        if ( !skip( $this->handle, $box->content_size - 8 ) ) {369          return TRUNCATED;370        }371      } else if ( $box->type == 'pixi' ) {372        // See ISO/IEC 23008-12:2017(E) 6.5.6.2373        if ( $box->content_size < 1 ) {374          return INVALID;375        }376        if ( !( $data = read( $this->handle, 1 ) ) ) {377          return TRUNCATED;378        }379        $num_channels = read_big_endian( $data, 1 );380        if ( $num_channels < 1 ) {381          return INVALID;382        }383        if ( $box->content_size < 1 + $num_channels ) {384          return INVALID;385        }386        if ( !( $data = read( $this->handle, 1 ) ) ) {387          return TRUNCATED;388        }389        $bit_depth = read_big_endian( $data, 1 );390        if ( $bit_depth < 1 ) {391          return INVALID;392        }393        for ( $i = 1; $i < $num_channels; ++$i ) {394          if ( !( $data = read( $this->handle, 1 ) ) ) {