title: Preparing audio file to be used in EME
body: <p>I want to process <code>wav</code> files so I can use them in the browser with MSE and EME.</p>
  <p>I am able to convert to <code>.mp4</code> and play with MSE, but when I encrypt the file the player doesn't work. No error is triggered, the <code>encrypted</code> event in EME never fires. So keys are never asked to be confirmed.</p>
  <p>What can I me doing wrong? How should I convert/encrypt the file?</p>
  <p>My pipeline of command right now:</p>
  <pre><code>ffmpeg -i long_input_44100.wav -ar 48000 -ac 2 output/long_input_44100_000.wav 
  ffmpeg -i output/long_input_44100_000.wav -strict experimental output/long_input_44100_000.mp4 
  MP4Box -dash 10000 -frag 10000 -rap output/long_input_44100_000.mp4 
  ffmpeg -y 
      -i output/long_input_44100_000.mp4 
      -encryption_scheme cenc-aes-ctr 
      -encryption_key 76a6c65c5ea762046bd749a2e632ccbb 
      -encryption_kid a7e61c373e219033c21091fa607bf3b8 
      -frag_duration 10000 
      output/long_input_44100_000_encrypted.mp4
  </code></pre>