downloading - Start serving file while converting it [PHP] -

i'm wondering how serve file while i'm converting it, lower thhe waiting time of client. i'v tried chunked header in php, first bytes of file downloaded.

    header('transfer-encoding: chunked');     header('content-type:audio/mpeg');     header('connection: keep-alive');     header('content-disposition: attachment; filename="' . basename($mp3file) . '"');      header('connection: close');     ob_clean();     flush();      $buffer = '';     $handle = fopen($mp3file, 'rb');     if($handle === false){         return false;     }      while(!feof($handle)){         $buffer = fread($handle, 8192);          echo sprintf("%x\r\n", strlen($buffer));         echo $buffer;         echo "\r\n";          ob_flush();         flush();     }      echo sprintf("%x\r\n", 0);     echo "\r\n";        fclose($handle); 

so i'm asking here, in case 1 found trick or whatever.