title: MP4 and AAC file extensions
body: <p>I may have realized that users can easily can create a protected file extension.
  The first two that exist are AAC and MP4.</p>
  
  <p>Some questions:</p>
  
  <ol>
  <li>How did they create those protected file extensions?</li>
  <li>What programming language is that done in?</li>
  <li>Can users burn those protected file extensions; whereas, they cannot rip them from optical medium afterwards?</li>
  <li>Why did Apple developers stopped using the protected versions of those file formats?</li>
  <li>How can I revert those file formats to protected?</li>
  </ol>