title: fulent-ffmpeg arguments inputs are invalid | nodejs
body: <p>how would I write this command</p>
  <p><code>ffmpeg -i input.mov -preset slow -codec:a libfdk_aac -b:a 128k -codec:v libx264 -pix_fmt yuv420p -b:v 2500k -minrate 1500k -maxrate 4000k -bufsize 5000k -vf scale=-1:720 output.mp4</code></p>
  <p>as a node fluent-ffmpeg command?</p>
  <p>what I have this</p>
  <pre><code>function convert(input, output, callback) {
    ffmpeg(input)
      .output(output)
      .outputOptions(
        &quot;-preset&quot;,&quot;slow&quot;,&quot;-codec:a&quot;,&quot;libfdk_aac&quot;,&quot;-b:a&quot;,&quot;128k&quot;,&quot;-codec:v&quot;,&quot;-pix_fmt&quot;,&quot;-b:v&quot;,&quot;2500k&quot;,&quot;-vf&quot;,&quot;scale&quot;,&quot;\&quot;-1:720\&quot;&quot;
      )
      .on(&quot;end&quot;, function () {
        console.log(&quot;conversion ended&quot;);
        callback(null);
      })
      .on(&quot;error&quot;, function (err) {
        console.log(&quot;error x: &quot;, err);
        callback(err);
      })
      .run();
  }
  </code></pre>
  <p>I get errors saying the arguments are invalid. such as but not limited to:</p>
  <ul>
  <li><code>Error: ffmpeg exited with code 1: &quot;-1:720&quot;: Invalid argument</code></li>
  </ul>
  <p>and other variations</p>