title: Ffmpeg pipe stream glitch
body: <p>I want to process ffmpeg raw video stream, and I can't understand why this code produces glitches. What's wrong?</p>
  
  <pre><code>ffmpeg -i in.mp4 -f image2pipe -pix_fmt rgb24 -vcodec rawvideo - | 
  ffmpeg -f rawvideo -vcodec rawvideo -s 1980x1080 -pix_fmt rgb24 -r 24 -i - -an out.avi
  </code></pre>
  
  <p>Thanks!</p>