script execution from php with timeout

gistfile1.txt

    // convert
    $timeout = 30;
    $descriptorspec = array(
      0 => array("pipe", "r"),  // stdin
      1 => array("pipe", "w"),  // stdout
      2 => array("pipe", "w"),  // stderr
    );
    $process = proc_open($youtdl, $descriptorspec, $pipes);
    var_dump($pipes);
    if (isset($stdin)) {
        fwrite($pipes[0],$stdin);
    }
    fclose($pipes[0]);

    stream_set_timeout($pipes[1], 0);
    stream_set_timeout($pipes[2], 0);

    $stdout = '';

    $start = microtime();

    while ($data = fread($pipes[1], 4096)) {
        $meta = stream_get_meta_data($pipes[1]);
        if (microtime()-$start>$timeout) break;
        if ($meta['timed_out']) continue;
        $stdout .= $data;
    }

    $stdout .= stream_get_contents($pipes[1]);
    $stderr = stream_get_contents($pipes[2]);
    $return = proc_close($process);