title: Overlaying multiple videos with ffmpeg
body: <p>I'm trying to overlay multiple videos into one video with ffmpeg. <a href="https://stackoverflow.com/questions/5890738/overlaying-video-with-ffmpeg">There is already a question with only one overlay</a>, but I want to add multiple videos at the same time (to avoid multiple encodings).</p>
  
  <p>I try to use following line:</p>
  
  <pre><code>ffmpeg -i background.m2v -vf "movie=a.m2v [a]; movie=b.m2v [b]; [in][a] overlay=0:366, [b] overlay=592:41" combined.m2v
  </code></pre>
  
  <p>The error is now, that the overlay area (0,366) – (720,942) is not within the main area (0,0) – (720, 210). But if I use only one overlay file alone it works.</p>
  
  <p>The sizes of the videos:</p>
  
  <ul>
  <li>background: 720x576</li>
  <li>a.m2v: 72x48</li>
  <li>b.m2v: 720x210</li>
  </ul>
  
  <p>In the result I want the a.m2v video in the top left corner (the logo) and the b.m2v as a lower third.</p>