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 four 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
• Alpha Four was released on December 15, 2004

The first beta release Beta-1 is expected later in 2005. 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.

Theora is named for Theora Jones, Edison Carter's Controller on the Max Headroom television program.

History

September 6, 2001 

On2 releases the source code to their libraries for VP3 under the terms of the VP3.2 Public License.

March 27, 2002 

On2's founder and CTO, Dan Miller, sends an email to vorbis-dev (http://www.xiph.org/archives/vorbis-dev/200203/0174.html) announcing On2's interest in collaborating with the Xiph.org Foundation and relicensing VP3 under the terms of the LGPL.

June 24, 2002 

On2 and the Xiph.org Foundation announce their alliance to develop Ogg Theora: the integration of VP3 with the Ogg framework and Vorbis. See also On2's press release (http://on2.com/pressreleases.php3?qs1=vp3_combines_with_vorbis).

September 25, 2002 

Theora Alpha One is released. See also On2's press release (http://on2.com/pressreleases.php3?qs1=On2_Xiph_Announce_Theora_Alpha).

December 16 and December 27, 2002 

Theora Alpha Two is released in two stages.

May 18, 2003 

Published VP3 legacy codec binaries.

June 9, 2003 

Theora reference implementation Alpha Two is released.

January 23, 2004 

Milestone 2 release of the RealNetworks Helix player includes preliminary support for Ogg Theora. Milestone 3, scheduled release in April 2004, is planned to provide complete support. See also the status at helixcommunity.org (https://xiph.helixcommunity.org/)

March 20, 2004 

Theora reference implementation Alpha Three is released.

May 10, 2004 

Theora/Vorbis plug-in version 0.2 for the Windows version of RealPlayer is released. Download it from helixcommunity.org (https://helixcommunity.org/project/showfiles.php?group_id=7).

June 1, 2004 

The Theora bitstream format has been frozen. It has not been changed from Alpha Three. So it is guaranteed that all files encoded using Alpha Three (or any later version) will be supported by future decoders.

External links

• Theora.org (http://www.theora.org/)
• Xiph.org Foundation (http://xiph.org/)
• On2 Technologies (http://on2.com/)
• VP3.com (http://vp3.com/)