title: FFMpeg takes up the whole cpu and spams log on bug encounter
body: <p>I have FFMpeg working on backend of website converting image + music to video. Every once in a while (probably 1/200 files), someone uploads something and cpu is always at 100% spamming error into log and filling up the whole space on drive, making the app unusable. </p>
  
  <p>I have literally at least a bilion lines of this in log </p>
  
  <pre><code>[png @ 0x50f0700] Invalid PNG signature 0x2020202020202020.
  Error while decoding stream #0:0: Invalid data found when processing input
  </code></pre>
  
  <p>Here is an example of command that caused it this time : </p>
  
  <pre><code>ffmpeg -y -v error -loop 1 -r 1 -i image.png -i song.mp3 -vcodec libx264 -acodec copy -vf scale=trunc(iw/2)*2:trunc(ih/2)*2 -preset ultrafast -r 1 -shortest output.mp4
  </code></pre>
  
  <p>What can I do if I don't have a control over files that get converted ?</p>