Editing Theora (section)

===Move to free software===
In August 2001, On2 Technologies announced that they would release an open source version of their VP3.2 video compression algorithm.<ref>{{citation |url=http://www.on2.com/index.php?id=486&news_id=365 |title=On2 Technologies to Open Source VP3.2 Video Compression Technology (archived website) |author=On2 |date=7 August 2001 |archive-url=https://web.archive.org/web/20071203062120/www.on2.com/index.php?id=486&news_id=365 |archive-date=3 December 2007}}</ref><ref>{{cite web|last=Mariano|first=Gwendolyn|title=On2's video codec to go open-source|url=http://news.cnet.com/2100-1023-271254.html|work=CNET|date=7 August 2001}}</ref> In September 2001, On2 Technologies published the [[source code]] of the VP3.2 codec under the VP3.2 Public License 0.1,<ref name="vp32license-01">{{citation
  | title = VP3.2 Public License 0.1
  | year = 2001
  | author = On2 Technologies
  | publisher = Xiph.Org Foundation
  | url = https://trac.xiph.org/browser/branches/vp32/vp32/VP32_license.txt
  | access-date = 10 February 2008
  | archive-date = 4 April 2016
  | archive-url = https://web.archive.org/web/20160404101159/https://trac.xiph.org/browser/branches/vp32/vp32/VP32_license.txt
  | url-status = dead
  }}</ref> a custom open-source license.<ref>{{cite web|last=Bernat|first=Bill|title=On2 Offers Up VP3.2 Source Code|url=https://www.streamingmedia.com/Articles/ReadArticle.aspx?ArticleID=64360|work=StreamingMedia.com|date=7 September 2001}}</ref><ref>{{citation |url=http://www.on2.com/index.php?id=486&news_id=364  |title=On2 Technologies Makes Video Compression Technology Available to Open-Source Community |author=On2 |date=7 September 2001 |archive-url = https://web.archive.org/web/20071207021659/www.on2.com/index.php?id=486&news_id=364 |archive-date = 7 December 2007}}</ref> The license only granted the right to modify the source code if the resultant larger work continued to support playback of VP3.2 data.<ref name="vp32license-01" /><ref>{{cite mailing list |url=https://lists.xiph.org/pipermail/vorbis/2001-September/004554.html |title=VP3.2 video codec open sourced|mailing-list=vorbis |last=Seibert |first=Stan |date=September 2001}}</ref>

In March 2002, On2 responded to the public's reception by relicensing the VP3 codec under the [[GNU Lesser General Public License]].<ref>{{cite press release |title=On2 Alters Licensing Terms for VP3; Company Responds to Open Source Community Demands. |url=http://www.thefreelibrary.com/On2+Alters+Licensing+Terms+for+VP3%3b+Company+Responds+to+Open+Source...-a084233138 |publisher=On2 Technologies |date=28 March 2002 |access-date=16 August 2009 |archive-date=4 December 2010 |archive-url=https://web.archive.org/web/20101204092727/www.thefreelibrary.com/On2+Alters+Licensing+Terms+for+VP3%3b+Company+Responds+to+Open+Source...-a084233138 |url-status=dead }}</ref> In June 2002, On2 donated VP3 to the Xiph.Org Foundation and offered it under the Ogg Vorbis [[BSD License|BSD]]-style license.<ref>{{Cite web | author=Xiph.Org Foundation | title = Theora Specification | url = https://theora.org/doc/Theora.pdf | date = 3 June 2017 | publisher=Xiph.Org Foundation | page=1}}</ref><ref>{{citation |url=http://www.on2.com/index.php?id=486&news_id=313 |title=VP3 Combines with Vorbis to Create First Open-Source Multimedia Platform |website=On2 |date=24 June 2002 |archive-url=https://web.archive.org/web/20071203061350/http://www.on2.com/index.php?id=486&news_id=313 |archive-date=3 December 2007}}</ref><ref name="linux-com-ogg">Linux.com (23 June 2002) [https://www.linux.com/news/ogg-vorbis-vp3-combining-forces-create-open-source-multimedia-package/ Ogg Vorbis, VP3 combining forces to create Open Source multimedia package], Retrieved on 2009-08-16</ref><ref>InternetNews.com (24 June 2002) [http://www.internetnews.com/bus-news/article.php/1370341 On2 Throws More Open-Source at MPEG-4], Retrieved on 16 August 2009</ref> On2 also made an irrevocable, [[royalty-free]] license grant for any patent claims it might have over the software and any derivatives,<ref name="theoraspec" /> allowing anyone to use any VP3-derived codec for any purpose.<ref name="theora-license">Xiph.org [http://svn.xiph.org/trunk/theora/LICENSE libtheora license (Subversion – Trunk)], Retrieved on 16 August 2009</ref><ref name="vp32-license">Xiph.org [http://svn.xiph.org/trunk/vp32/LICENSE VP32 codec license (Subversion – Trunk)], Retrieved on 16 August 2009</ref> In August 2002, On2 entered into an agreement with the Xiph.Org Foundation to make VP3 the basis of a new, free video codec, called Theora.<ref>The Free Library (1 August 2002) [https://www.thefreelibrary.com/ON2+SIGNS+PACT+WITH+XIPH.ORG+TO+DEVELOP%2FSUPPORT+VP3-a089067501 On2 Signs Pact With Xiph.org to Develop/Support VP3], Retrieved on 16 August 2009</ref> On2 declared Theora to be VP3's successor.{{citation needed|date=January 2012}} On 3 October 2002, On2 and Xiph announced the completion and availability of the initial alpha code release of ''libtheora'', Theora's reference implementation.<ref>{{citation |url=http://www.on2.com/index.php?id=486&news_id=298 |title=On2 and Xiph Announce Alpha Code Release of Theora, VP3-Vorbis-Based Multimedia Solution |author=On2 |date=3 October 2002 |archive-url=https://web.archive.org/web/20071204072126/www.on2.com/index.php?id=486&news_id=298 |archive-date=4 December 2007}}</ref>

There is no formal specification for VP3's [[bitstream format]] beyond the VP3 source code published by On2 Technologies. In 2003, Mike Melanson created an incomplete description of the VP3 bitstream format and decoding process at a higher level than source code, with some help from On2 and Xiph.Org Foundation. The Theora specification adopted some portions of this VP3 description.<ref name="theoraspec" /><ref name="vp3-bitstream">{{citation
 |title       = VP3 Bitstream Format and Decoding Process
 |date        = 8 December 2004
 |author      = Mike Melanson (mike at multimedia.cx)
 |publisher   = Multimedia.cx
 |url         = http://www.multimedia.cx/vp3-format.txt
 |access-date  = 27 September 2009
 |url-status     = dead
 |archive-url  = https://archive.today/20130106025121/www.multimedia.cx/vp3-format.txt
 |archive-date = 6 January 2013
}}</ref>

A successor to Theora, [[Daala]], was later merged into [[AV1]].<ref name=AOMCNet2015September>{{cite web |title=Tech giants join forces to hasten high-quality online video |publisher=[[CNET]] |author=Stephen Shankland |url=https://www.cnet.com/tech/services-and-software/tech-giants-join-forces-to-hasten-high-quality-online-video/ |date=2015-09-01 |access-date=2025-05-19}}</ref>