Have you installed all the necessary gstreamer plugins? I believe gstreamer0.10-ffmpeg enables aac playback.
** Changed in: totem (Ubuntu) Status: Unconfirmed => Needs Info -- Edgy: no audio for mp4 files https://launchpad.net/bugs/71689 -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs