title: Ffprobe with print json doesn't print anything
body: <p>I am trying to get information about a movie (resolution, frame rate, bit rate, codecs, duration etc) in a human readable way. I found this commnad:</p>
  
  <pre><code>ffprobe -v quiet -print_format json -show_format -show_streams somefile.asf
  </code></pre>
  
  <p>In this Stack Overflow question: <a href="https://stackoverflow.com/questions/7708373/get-ffmpeg-information-in-friendly-way">Get ffmpeg information in friendly way</a></p>
  
  <p>But it doesn't work for me. When I try it in a  terminal, the output is empty:</p>
  
  <pre><code>richard@richard-desktop:~/projects/hello-python$ ffprobe -v quiet -print_format json -show_format -show_streams tests/test_1.mpg 
  richard@richard-desktop:~/projects/hello-python$ 
  </code></pre>