Oggconvert is a small gnome utility which uses gstreamer to convert (almost) any media file to the patent-free ogg vorbis, theora and dirac formats.

the main interesting points are:
* it is very easy to use: drag a file onto the source bar (or use
the file chooser) and hit convert button. of course, you can also change
the video format, quality settings and the output filename if you like.
* it uses gstreamer, so it can convert (almost) any file totem can play.
* it can deal with audio-only files, video-only files, and files with many
audio tracks (such as dvd rips with a commentary track).
* thanks to the magic of gstreamer, metadata (for example, title and artist
info on an mp3) is preserved.
* adheres to the gnome hig as much as possible.
* supports the schroedinger encoder for encoding to the dirac video format
(note that this encoder is currently experimental).
* supports encoding to the matroska container format.