Theora is a video codec being developed by the Xiph.org Foundation as part of their Ogg project. Based upon On2 Technologies' VP3 codec, and christened by On2 as the successor in VP3's lineage, Theora is targeted at competing with MPEG-4 video (e.g., XviD and DivX), RealVideo, Windows Media Video, and similar lower-bitrate video compression schemes.
Theora is still in developmental stages with Xiph.org having made three alpha releases thus far.
- Alpha One was released on September 25, 2002
- Alpha Two was released half on December 16 and half on December 27, 2002
- Alpha Three was released on March 20, 2004
The first beta release Beta-1 is expected later in 2004. Theora is released under the terms of a BSD-style license.
While VP3 is patented technology, On2 has irrevocably given royalty-free license of the VP3 patents to all of humanity, enabling the public to utilize Theora and other VP3-derived codecs for any imaginable purpose.
In the Ogg multimedia framework, Theora provides a video layer, while Vorbis acts as the audio layer.