Avifinfo
Box::parse()
Reads the box header.
Method of the class: Box{}
No Hooks.
Return
Status
. FOUND on success or an error on failure.
Usage
$Box = new Box(); $Box->parse( $handle, $num_parsed_boxes, $num_remaining_bytes );
- $handle(stream) (required)
- The resource the header will be parsed from.
- $num_parsed_boxes(int) (required) (passed by reference — &)
- The total number of parsed boxes. Prevents timeouts.
- $num_remaining_bytes(int)
- The number of bytes that should be available from the resource.
Default: MAX_SIZE
Box::parse() Box::parse code WP 6.6.2
public function parse( $handle, &$num_parsed_boxes, $num_remaining_bytes = MAX_SIZE ) { // See ISO/IEC 14496-12:2012(E) 4.2 $header_size = 8; // box 32b size + 32b type (at least) if ( $header_size > $num_remaining_bytes ) { return INVALID; } if ( !( $data = read( $handle, 8 ) ) ) { return TRUNCATED; } $this->size = read_big_endian( $data, 4 ); $this->type = substr( $data, 4, 4 ); // 'box->size==1' means 64-bit size should be read after the box type. // 'box->size==0' means this box extends to all remaining bytes. if ( $this->size == 1 ) { $header_size += 8; if ( $header_size > $num_remaining_bytes ) { return INVALID; } if ( !( $data = read( $handle, 8 ) ) ) { return TRUNCATED; } // Stop the parsing if any box has a size greater than 4GB. if ( read_big_endian( $data, 4 ) != 0 ) { return ABORTED; } // Read the 32 least-significant bits. $this->size = read_big_endian( substr( $data, 4, 4 ), 4 ); } else if ( $this->size == 0 ) { $this->size = $num_remaining_bytes; } if ( $this->size < $header_size ) { return INVALID; } if ( $this->size > $num_remaining_bytes ) { return INVALID; } $has_fullbox_header = $this->type == 'meta' || $this->type == 'pitm' || $this->type == 'ipma' || $this->type == 'ispe' || $this->type == 'pixi' || $this->type == 'iref' || $this->type == 'auxC'; if ( $has_fullbox_header ) { $header_size += 4; } if ( $this->size < $header_size ) { return INVALID; } $this->content_size = $this->size - $header_size; // Avoid timeouts. The maximum number of parsed boxes is arbitrary. ++$num_parsed_boxes; if ( $num_parsed_boxes >= MAX_NUM_BOXES ) { return ABORTED; } $this->version = 0; $this->flags = 0; if ( $has_fullbox_header ) { if ( !( $data = read( $handle, 4 ) ) ) { return TRUNCATED; } $this->version = read_big_endian( $data, 1 ); $this->flags = read_big_endian( substr( $data, 1, 3 ), 3 ); // See AV1 Image File Format (AVIF) 8.1 // at https://aomediacodec.github.io/av1-avif/#avif-boxes (available when // https://github.com/AOMediaCodec/av1-avif/pull/170 is merged). $is_parsable = ( $this->type == 'meta' && $this->version <= 0 ) || ( $this->type == 'pitm' && $this->version <= 1 ) || ( $this->type == 'ipma' && $this->version <= 1 ) || ( $this->type == 'ispe' && $this->version <= 0 ) || ( $this->type == 'pixi' && $this->version <= 0 ) || ( $this->type == 'iref' && $this->version <= 1 ) || ( $this->type == 'auxC' && $this->version <= 0 ); // Instead of considering this file as invalid, skip unparsable boxes. if ( !$is_parsable ) { $this->type = 'unknownversion'; } } // print_r( $this ); // Uncomment to print all boxes. return FOUND; }