Elisa/Phonon - Gstreamer configuration?

By and large, multimedia Just Works on my systems. For most general stuff, I use Xine (via Phonon, through Amarok and Dragon Player). The rest of the time, I typically use (S)Mplayer. So long as I pick the right -vo option for my card, it works just fine.

So anyways, I try out Elisa, because I’m constantly on the verge of building a Linux-based home theater box. Has great potential, but the local video playback is terrible. By “local” I mean “not grabbed through Elisa’s internet scripts like Apple Trailers.”

.AVI and .MKV files that Xine and SMplayer have no issue with whatsoever give Elisa fits. The video immediately falls out of sync with the audio, and there is a bit of artifacting. DVD playback is especially corrupted - large amounts of artifacting and unreadable fonts in the DVD menus.

I find out that Elisa uses Gstreamer for its backend. To try and figure out if it was Elisa or Gstreamer causing the problems, I told Phonon to use Gstreamer as a back-end and tried the same files in Dragon Player. Standard-def stuff was still fine, 480p stuff was choppy, and anything else (720p .mkv’s and DVD) wouldn’t play at all. I’d just get a “no media loaded” dialog.

I’m looking at Gstreamer as being a problem. I’ve follows the ten steps relatively closely (grabbed libdvdcss from elsewhere, so never dealt with vlc’s repo to begin with). I have all the gstreamer packages installed from packman, so everything should be fine, package-wise.

The performance is just terrible compared to Xine and Mplayer, though. And I’m not sure how to configure it. The only “settings” I see for Elisa are folders to scan and user accounts to register. As for Phonon, there aren’t any specific options for the Gstreamer back-end (using the latest 4.2 from Factory: Desktop repo). Gstreamer’s site doesn’t have much in the way of normal user documentation, either.

So, I’m at a loss. How can I make Gstreamer behave itself?