title: using ffmpeg with python, Input buffer exhausted before END element found
body: <p>When I run this from command line everything is fine</p>
  
  <pre><code>ffmpeg -i input.mp4 -f mp3 -ab 320000 -vn output.mp3 
  </code></pre>
  
  <p>But when I call the same from python</p>
  
  <pre><code>subprocess.call(['ffmpeg', '-i', 'input.mp4', '-f', 'mp3', '-ab', '320000', '-vn', 'output.mp3'])
  </code></pre>
  
  <p>After several seconds converting I'm getting this error</p>
  
  <pre><code>[aac @ 0x7fb3d803e000] decode_band_types: Input buffer exhausted before 
  END element found
  Error while decoding stream #0:1: Invalid data found when processing 
  input
  [mov,mp4,m4a,3gp,3g2,mj2 @ 0x7fb3d8000000] stream 1, offset 0x80011d: 
  partial file
  input.mp4: Invalid data found when processing input
  </code></pre>
  
  <p>Any ideas? </p>