title: How to get the file extension from an AVAsset or AVAssetTrack
body: <p>I've a audio file (mp3, wav, aiff, ...) in an <code>AVAsset</code> then get the <code>AVAssetTrack</code>.</p>
  
  <p>I'm looking for a way of finding the audio file type (mp3, wav, aiff, ...) from this asset in a Apple format like <code>AVFileType</code> or <code>AudioFileTypeID</code>?</p>
  
  <p>For the moment the only way I find to get the audio file type is to use <code>formatDescriptions</code> property of <code>AVAssetTrack</code> and get the subType as showed in the <a href="https://developer.apple.com/documentation/avfoundation/avassettrack/1386694-formatdescriptions" rel="nofollow noreferrer">documentation</a> but it doesn't work very well since I cannot determine which uncompressed format I have (wav or aiff) because I just get "lpcm" format...</p>
  
  <p>Isn't possible to get the <code>AVFileType</code> from an <code>AVAsset</code>?</p>