title: AVAssetExportSession exportAsynchronouslyWithCompletionHandler: Source frame unsupported format
body: <p>I am using <code>AVAssetExportSession</code> to export a video selected from library. It works great for all videos of all types except landscape-recorded screen recordings (using the screen recording feature in iOS 11). Weird enough, it works perfectly for other landscape videos, and it also works perfectly for portrait videos of the same screen recording feature. But I've tried two videos that are landscape screen recordings, and they both failed with the error <code>Source frame unsupported format</code>.</p>
  
  <p>How can I fix this problem?</p>
  
  <p><strong>UPDATE:</strong> Videos play just fine both in Photos and in my app before exporting.</p>