http://bugs.winehq.org/show_bug.cgi?id=22780
--- Comment #9 from Vincent Povirk madewokherd@gmail.com 2010-07-23 11:15:57 --- Yes, the decoder should seek to the beginning of the stream. But there's no reason to use source_mgr_init_source for this. Just seek to the start in Initialize.
Possibly CreateDecoderFromStream and/or MatchesPattern needs to be modified, but that requires a test.