mplayer recently got dirac support (to be exact, two kinds of dirac support, one through dirac and one through schroedinger). Current mplayer ebuild automagically enables dirac support if one of those libs is there. I'm not sure if we should add two useflags or just dirac and enable both dirac decoders on that.
Thanks, I've added the useflags. libschroedinger is way much faster, but I tend to prefer the quality when encoding with libdirac, so I made it two useflags so that people can have a finegrained choice.