Get version in which SWF file is compiled

flash_version_in_swf.php

<?php
/**
 * Get version in which SWF file is compiled
 * @param  string $file_path Path to SWF file
 * @return int               Version number (or -1 on error)
 */
function swf_version($file_path){

  $ret = -1;
  $fh = @fopen($file_path, "r");

  if ($fh !== false){

    // Read first 8 bytes
    $header = fread($fh, 7);
    fclose($fh);

    // Seperate first 4 header bytes
    list($c, $w, $s, $v) = $header;
    $v = !is_null($v) ? ord($v) : 0;

    // Verify that this is SWF header
    if (in_array($c, array("C", "F")) && ($w == "W" && $s == "S"))
      $ret = $v;

  }

  return $ret;

}