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There is no formal specification for the VP3 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.
VP3 was originally a proprietary and patented video codec. On2 TrueMotion VP3.1 was introduced in May 2000 followed three months later by the VP3.2 release. Later that year, On2 announced VP3 plugins for QuickTime and RealPlayer. In May 2001, On2 released the beta version of its new VP4 proprietary codec. In June 2001, On2 also released a VP3 codec implementation for Microsoft Windows where the encoder was priced at $39.95 for personal use, and $2,995 for limited commercial use. In August 2001, On2 Technologies announced that they would be releasing an open source version of their VP3.2 video compression algorithm. In September 2001 they published the source code and open source license for VP3.2 video compression algorithm at www.vp3.com. The VP3.2 Public License 0.1 granted the right to modify the source code only if the resulting larger work continued to support playback of VP3.2 data.
Move to free software 
In September, 2001 it was donated to the public as open source, and On2 irrevocably disclaimed all rights to it, including a royalty-free license grant for any patent claims it might have over the software and any derivatives their patents on the technology, allowing anyone to use any VP3-derived codec for any purpose. In March 2002, On2 altered licensing terms required to download the source code for VP3 to LGPL.
The free video codec Theora was forked off from the released codebase of VP3.2 and further developed into an independent codec. On2 declared Theora to be the successor in VP3's lineage.
Theora I saw its bitstream format freeze in June 2004. The Theora I Specification was completely published in 2004. Any later changes in the specification are minor updates. A first stable release (version 1.0) of the Theora reference implementation (libtheora) was released in November 2008.
VP4 was announced in January 2001. On2 Technologies released the beta version of VP4 on May 21, 2001. In June 2001 On2 Technologies posted the production release of VP4 on its website. VP4 brought an improved encoder for VP3 bitstream format. So because of keeping the bitstream format VP4 can't be seen as an individual codec.
On July 19, 2001 On2 announced an agreement with RealNetworks to license its VP4 video compression technology, for set-top boxes and other devices. On2 enabled RealPlayer as the exclusive media player for the VP4 codec and the RealSystem iQ architecture became the only streaming media platform capable of delivering the VP4 codec. The first beta version of a plug-in for RealPlayer was announced in January 2002.
See also 
- "On2 Introduces TrueMotion VP3.2" (Press release). On2. 16 August 2000. Retrieved 11 August 2009.
- "On2.com Launches Next Generation of Revolutionary Broadband Video Technology" (Press release). On2. 17 May 2000. Retrieved 11 August 2009.
- "On2's VP3 Codec Available Via QuickTime 5's Component Download Feature" (Press release). On2. 10 October 2000. Retrieved 18 August 2009.
- "On2 Plug-In for RealNetworks Server to be Distributed on Akamai Network" (Press release). On2. 23 October 2000. Retrieved 18 August 2009.
- "On2 to Debut VP4 for the Web, Part of New Website Launch" (Press release). On2. 18 May 2001. Retrieved 16 August 2009.
- "On2 Posts Production Release of VP4 Codec" (Press release). On2. 20 June 2001. Retrieved 16 August 2009.
- "On2 Technologies Announces Global Release of VP3 for Windows" (Press release). On2. 15 May 2001. Retrieved 18 August 2009.
- The Free Library (2001-06-27) VP3 for Windows Now Available for License At On2.com., Retrieved on 2009-08-18
- On2 (2001-08-07) On2 Technologies to Open Source VP3.2 Video Compression Technology, Retrieved on 2009-08-16
- CNET News (2001-08-07) On2's video codec to go open-source, Retrieved on 2009-08-16
- On2 Technologies (2001), VP3.2 Public License 0.1, Archive.org, archived from the original on 26 October 2001, retrieved 22 September 2009
- On2 Technologies (2001), VP3.2 Public License 0.1, Xiph. Org Foundation, retrieved 10 February 2008
- StreamingMedia.com (2001-09-07) On2 Offers Up VP3.2 Source Code, Retrieved on 2009-08-16
- On2 (2001-09-07) On2 Technologies Makes Video Compression Technology Available to Open-Source Community, Retrieved on 2009-08-16
- Linux.com (2001-09-06) On2 Technologies Open-Sources VP3 video compression code, Retrieved on 2009-08-16
- lists.xiph.org (2001-09-09) Vorbis mailing list - VP3.2 video codec open sourced, Retrieved on 2009-08-16
- Xiph. Org Foundation (5 August 2009), Theora Specification (PDF), Xiph. Org Foundation, retrieved 25 September 2009
- Xiph.org libtheora license (Subversion - Trunk), Retrieved on 2009-08-16
- Xiph.org VP32 codec license (Subversion - Trunk), Retrieved on 2009-08-16
- The Free Library (2002-03-28) On2 Alters Licensing Terms for VP3; Company Responds to Open Source Community Demands., Retrieved on 2009-08-16
- On2 (2002-06-24) VP3 Combines with Vorbis to Create First Open-Source Multimedia Platform, Retrieved on 2009-08-16
- InternetNews.com (2002-06-24) On2 Throws More Open-Source at MPEG-4, Retrieved on 2009-08-16
- Giles, Ralph (1 June 2004). "Theora I bitstream freeze". theora-dev mailing list. http://lists.xiph.org/pipermail/theora-dev/2004-June/001112.html. Retrieved 25 September 2009.
- Xiph. Org Foundation (17 September 2004). "Theora I Specification, Xiph.org Foundation, September 17, 2004" (PDF). Archive.org. Archived from the original on 28 September 2004. Retrieved 26 September 2009
- Giles, Ralph (3 November 2008). "Theora 1.0 final release!". theora-dev mailing list. http://lists.xiph.org/pipermail/theora-dev/2008-November/003736.html. Retrieved 4 November 2008.
- "The Xiph. Org Foundation announces the release of Theora 1.0" (Press release). Xiph. Org Foundation. 3 November 2008. Retrieved 6 August 2009.
- On2 (2001-01-09) On2 and Equator Enter Into a Formal Licensing Agreement, Retrieved on 2001-01-09
- On2 (2001-05-18) On2 to Debut VP4 for the Web, Part of New Website Launch, Retrieved on 2009-08-16
- On2 (2001-07-19) On2's VP4 Video Compression Technology to Exclusively Support RealNetworks' RealPlayer and RealSystem iQ, Retrieved on 2009-08-16
- StreamingMedia.com (2001-07-19) Exclusive Deal for On2 and Real, Retrieved on 2009-08-16
- On2 (2002-01-22) On2's VP4 for Real Now Available, Retrieved on 2009-08-16