GStreamer is a library that allows the construction of graphs of media-handling components, ranging from simple mp3 playback to complex audio (mixing) and video (non-linear editing) processing. Applications can take advantage of advances in codec and filter technology transparently. Developers can add new codecs and filters by writing a simple plugin with a clean, generic interface. This package provides the ogg plugin for GStreamer, which lets it handle OGG media containers. You'll probably want to install gst-plugins1-vorbis and gst-plugins1-theora too, which provide its respective audio and video codecs.