Avifinfo

Parser::parse_ftyp │ public │ WP 1.0

Parses a file stream.

The file type is checked through the "ftyp" box.

Method of the class: Parser{}

No Hooks.

Returns

true|false. True if the input stream is an AVIF bitstream or false.

Usage

$Parser = new Parser();
$Parser->parse_ftyp();

Parser::parse_ftyp() code WP 6.9.1

wp-includes/class-avif-info.php 
public function parse_ftyp() {
  $box    = new Box();
  $status = $box->parse( $this->handle, $this->num_parsed_boxes );
  if ( $status != FOUND ) {
    return false;
  }

  if ( $box->type != 'ftyp' ) {
    return false;
  }
  // Iterate over brands. See ISO/IEC 14496-12:2012(E) 4.3.1
  if ( $box->content_size < 8 ) {
    return false;
  }
  for ( $i = 0; $i + 4 <= $box->content_size; $i += 4 ) {
    if ( !( $data = read( $this->handle, 4 ) ) ) {
      return false;
    }
    if ( $i == 4 ) {
      continue; // Skip minor_version.
    }
    if ( substr( $data, 0, 4 ) == 'avif' || substr( $data, 0, 4 ) == 'avis' ) {
      return skip( $this->handle, $box->content_size - ( $i + 4 ) );
    }
    if ( $i > 32 * 4 ) {
      return false; // Be reasonable.
    }

  }
  return false; // No AVIF brand no good.
}