Make thumbnail from interlaced video

<a href="https://github.com/mguiral"><img src="https://avatars.githubusercontent.com/u/1543779?v=3" align="left" width="96" height="96" hspace="10"></img></a> **Issue by [mguiral](https://github.com/mguiral)**
_Thursday Sep 17, 2015 at 16:57 GMT_
_Originally opened as https://github.com/mikrosimage/avTranscoder/issues/228_

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