MGA XV Overlay Size?

[j. berger]

Does the  mga driver have a 1024x1024 size restriction for xv overlays?
  If so is there a way to configure xorg.conf for a larger size?  Or is
it a restriction of my g400 graphics card?  I have a MythTV backend that
I would like to use to edit HDTV mpeg files with.  Mythfrontend just
shows a blank screen when I try to view them.  If I try to play the
mpegs with mplayer it errors out with "[xv] Source image dimensions are
too high: 1920x1080 (maximum is 1024x1024)."   I would even be happy if
it supported 1280x720.