title: Show media preview in QML / QtQuick2
body: <p>I am successfully playing video from QML using <code>MediaPlayer</code> and <code>VideoOutput</code> elements, however is there any native/simple/recommended practice of generating preview icons for media source such as video files and/or streams?</p>
  
  <p>Example: In my application I have a list of files that I show to the user in a list. When the user clicks an item it will start playing. To aid the user in selecting the desired item, I would like to decorate each item with a small image icon that shows a frame of the video for that item. If the item does not contain video, it will simply show a generic picture icon instead.</p>
  
  <p>How would I go about this?</p>