title: FFmpeg: Add cover art to MP4
body: <p>I want to merge an audio and video file and add a cover to it.</p>
  <p>I have the following files:</p>
  <p>audio.mp4</p>
  <p>video.mp4</p>
  <p>cover.jpg</p>
  <p>I've found the following example in the ffmpeg documentation:</p>
  <pre><code>ffmpeg -i in.mp4 -i IMAGE -map 0 -map 1 -c copy -c:v:1 png -disposition:v:1 attached_pic out.mp4
  </code></pre>
  <p>But I'm not sure how to modify it for my three inputs.</p>