title: Trim mp4 files without encoding it again
body: <p>I have a .mp4 video file, I need to trim it, however no matter how I do it, trimmed video is being encoded again which results in noisy video.</p>
  
  <p>What I've tried:</p>
  
  <ol>
  <li><p>Open video with Matlab, read frames and write only the frames that I want to have in trimmed video, I use <code>'MPEG-4'</code> option.</p></li>
  <li><p>Trim video using Windows Movie Maker.</p></li>
  <li>Trim video using VirtualDub.</li>
  </ol>
  
  <p>In first 2 scenarios original mp4 movie is encoded again after trimming it. I couldn't get mp4 files open in VirtualDub.</p>
  
  <p>So what would be the easiest way to trim a video without re-encdong it?</p>