http://sourceforge.net/tracker/index.php?func=detail&aid=1691505&group_id=5776&atid=305776
Allow more control to advanced MPEG encoding application
Summary: exposed inner steps inside SeqEncoder::EncodeStream() to user
allowing finer control.
SeqEncoder::EncodeStream() currently parses image stream using 'pull'
method, calling reader from inside the long loop.
