function BigEndian2Int($byte_word, $signed = false) { 
  $int_value = 0; 
  $byte_wordlen = strlen($byte_word); 
  for ($i = 0; $i < $byte_wordlen; $i++) { 
    $int_value += ord($byte_word{$i}) * pow(256, ($byte_wordlen - 1 - $i)); 
  } 
  if ($signed) { 
    $sign_mask_bit = 0x80 << (8 * ($byte_wordlen - 1)); 
    if ($int_value & $sign_mask_bit) { 
      $int_value = 0 - ($int_value & ($sign_mask_bit - 1)); 
    } 
  } 
  return $int_value; 
} 
//獲得視頻的數字時間 
function getFlvDuration($name){ 
  if(!file_exists($name)){ 
    return; 
  } 
  $flv_data_length=filesize($name); 
  $fp = @fopen($name, 'r'); 
  $flv_header = fread($fp, 5); 
  fseek($fp, 5, SEEK_SET); 
  $frame_size_data_length = $this->BigEndian2Int(fread($fp, 4)); 
  $flv_header_frame_length = 9; 
  if ($frame_size_data_length > $flv_header_frame_length) { 
    fseek($fp, $frame_size_data_length - $flv_header_frame_length, SEEK_CUR); 
  } 
  $duration = 0; 
  while ((ftell($fp) + 1) < $flv_data_length) { 
     $this_tag_header   = fread($fp, 16); 
     $data_length     = $this->BigEndian2Int(substr($this_tag_header, 5, 3)); 
     $timestamp      = $this->BigEndian2Int(substr($this_tag_header, 8, 3)); 
     $next_offset     = ftell($fp) - 1 + $data_length; 
     if ($timestamp > $duration) { 
     $duration = $timestamp; 
     } 
     fseek($fp, $next_offset, SEEK_SET); 
  } 
  fclose($fp); 
  return $duration; 
} 
//轉化為0：03：56的時間格式 
function getFlvTime($time){ 
  $num = $time; 
  $sec = intval($num/1000); 
  $h = intval($sec/3600); 
  $m = intval(($sec%3600)/60); 
  $s = intval(($sec%60)); 
  $tm = $h.':'.$m.':'.$s; 
  return $tm; 
}