Signed-off-by: Wolfram Gloger <wmglo@dent.med.uni-muenchen.de>

Modify the parser initialization so that parsers can
set pict_type themselves.  Use this in the mpegvideo parser
so that initial frames are not unconditionally I frames.
I have had this in my tree for several years.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>