View source for Theora

{{Short description|Free lossy video compression format}}
{{For|the genus of clams|Theora (bivalve)}}
{{Use dmy dates|date=October 2021}}
{{Infobox file format
| logo                   = Theora logo 2007.svg
| screenshot             =
| caption                =
| extension              = .ogv, .ogg
| mime                   = video/ogg
| type code              =
| uniform type           =
| magic                  =
| owner                  = [[Xiph.Org Foundation]]
| released               = {{start date|df=yes|2004|06|01}}<ref name= "theora-freeze">{{cite mailing list | url = https://lists.xiph.org/pipermail/theora-dev/2004-June/001112.html | title = Theora I bitstream freeze | mailing-list = theora-dev | date = 1 June 2004 | last = Giles |first = Ralph |access-date= 19 May 2025}}</ref>
| latest release version = Theora I
| latest release date    = 3 June 2017<ref name="theoraspec">{{Cite web | title = Theora Specification | url = https://theora.org/doc/Theora.pdf | access-date= 19 May 2025 | date = 3 June 2017 | publisher=Xiph.Org Foundation }}</ref>
| type                   = [[Video coding format]]
| container for          =
| contained by           = [[Ogg]], [[Matroska]]
| extended from          = [[VP3]]
| extended to            =
| open                   = Yes<ref>{{cite web|url=https://www.fsf.org/campaigns/playogg/en/|title=PlayOgg! – FSF – Free Software Foundation |access-date=2025-05-19|date=2010-03-17}}</ref>
| free                   = Yes<ref>{{cite web |title=Theora FAQ |url=https://xiph.org/theora/faq/ |website=Xiph.org |access-date=1 December 2021 |archive-url=https://web.archive.org/web/20200926192702/https://xiph.org/theora/faq/ |archive-date=26 September 2020 |date=2016}}</ref>
| standard               = [https://www.theora.org/doc/Theora.pdf Specification]
| url                    = [https://www.theora.org/ theora.org]
}}
{{Infobox software
| name                   = libtheora
| logo                   =
| screenshot             =
| caption                =
| collapsible            =
| author                 =
| developer              = [[Xiph.Org Foundation]]
| released               = {{start date|df=yes|2008|11|03}} (1.0)
| discontinued           =
| latest_release_version = 1.2.0
| latest_release_date    = {{Start date and age|df=yes|2025|03|29}}<ref>{{cite web | url = https://www.xiph.org/press/2025/theora-release-1.2/ | title = Theora 1.2.0 release |access-date=29 March 2025 | publisher =Xiph.Org Foundation}}</ref>
| latest_preview_version = 1.2.0 Beta 1
| latest_preview_date    = {{Start date and age|df=yes|2025|03|16}}<ref>{{cite web | url = https://theora.org/news | title = Theora 1.2.0 beta 1|access-date=16 March 2025 | publisher =Xiph.Org Foundation}}</ref>
| frequently updated     =
| programming language   = [[C (programming language)|C]]
| operating_system       = [[Unix-like]] (incl [[Linux]], [[Mac OS X]]), [[Microsoft Windows|Windows]]
| operating_system_desc  =
| platform               =
| size                   =
| language               =
| genre                  = [[Video codec]], [[reference implementation (computing)|reference implementation]]
| license                = [[BSD licenses|3-clause BSD]]
| website                = {{URL|https://www.theora.org/}}
}}

'''Theora''' is a [[free file format|free]] [[Lossy compression|lossy]] [[video compression format]].<ref>{{Citation | url = https://www.theora.org | title = Theora}}.</ref> It was developed by the [[Xiph.Org Foundation]] and distributed without licensing fees alongside their other free and open media projects, including the [[Vorbis]] audio format and the [[Ogg]] container.

The '''libtheora''' [[video codec]] is the [[reference implementation (computing)|reference implementation]] of the Theora video compression format developed by the Xiph.Org Foundation.<ref name="libtheora-xiph">{{cite web | author=Xiph.Org Foundation | title = libtheora Documentation 1.1.0 | url = https://theora.org/doc/libtheora-1.1/ | access-date=25 September 2009 | publisher=Xiph.Org Foundation}}</ref><ref name="libtheora-ohloh">{{cite web | author=ohloh | author-link=ohloh | title=libtheora | url=http://www.ohloh.net/p/libtheora | access-date=25 September 2009 | publisher=[[ohloh]] | archive-date=10 October 2010 | archive-url=https://web.archive.org/web/20101010075905/http://www.ohloh.net/p/libtheora | url-status=dead }}</ref>

Theora was derived from the formerly [[Proprietary software|proprietary]] [[VP3]] codec, released into the [[public domain]] by [[On2 Technologies]]. It is broadly comparable in design and bitrate efficiency to [[MPEG-4 Part 2]], early versions of [[Windows Media Video]], and [[RealVideo]] while it lacked some of the features present in some of these other codecs. It is comparable in open standards philosophy to the [[BBC]]'s [[Dirac (video compression format)|Dirac]] codec.

Theora was named after [[Theora Jones]], [[Edison Carter]]'s Controller on the ''[[Max Headroom (TV series)|Max Headroom]]'' television program.<ref>{{cite web
  | publisher = Xiph.Org Foundation | title = Theora FAQ
  | url = https://theora.org/faq/#15 | access-date =6 August 2009
}}</ref>

==Technical details==
Theora is a [[variable bitrate|variable-bitrate]], [[discrete cosine transform|DCT]]-based video compression scheme. Like most common video codecs, Theora used [[chroma subsampling]], [[block (data storage)|block]]-based motion compensation and an 8-by-8 DCT block. Pixels are grouped into various structures, namely blocks, super blocks, and [[macroblocks]]. Theora supports intra-coded frames ("keyframes") and forward-predictive frames, but not [[B-frame|bi-predictive frames]] which are found in [[H.264]] and [[VC-1]]. Theora also does not support [[Interlaced video|interlacing]], or bit-depths larger than 8 bits per component.<ref name="theoraspec"/>

Theora video streams can be stored in any suitable [[container format (digital)|container format]], but they are most commonly found in the [[Ogg]] container with [[Vorbis]] or [[FLAC]] audio streams. This combination provided a completely open, royalty-free multimedia format. It can also be used with the [[Matroska]] container.<ref>{{cite web |title=Matroska Codec Specs |url=https://www.matroska.org/technical/codec_specs.html |access-date=19 May 2025 |publisher=Matroska}}</ref>

The Theora video-compression format is compatible with the VP3 video-compression format, which consisted of a backward-compatible superset.<ref name="theora-license" /><ref name="FAQ-VP3">Xiph.org [https://theora.org/faq/#VP3 FAQ – Theora and VP3]. Retrieved 2 September 2009</ref> Theora is a superset of VP3, and VP3 streams (with some minor syntactic modifications) can be converted into Theora streams without recompression (but not vice versa).<ref name="FAQ-VP3" /> VP3 video compression can be decoded using Theora implementations, but Theora video compression usually cannot be decoded using old VP3 implementations.

==History==
{{See also|VP3}}
Theora's predecessor ''On2 TrueMotion VP3'' was originally a [[proprietary software|proprietary]] and patent-encumbered [[video codec]] developed by [[On2 Technologies]]. VP3.1 was introduced in May 2000<ref>{{citation |url=http://www.on2.com/index.php?id=486&news_id=407  |title=On2.com Launches Next Generation of Revolutionary Broadband Video Technology |author=On2 |date=17 May 2000  |archive-url = https://web.archive.org/web/20071203064537/www.on2.com/index.php?id=486&news_id=407 |archive-date = 3 December 2007}}</ref> and followed three months later by the VP3.2 release,<ref>{{citation |url=http://www.on2.com/index.php?id=486&news_id=401 |title=On2 Introduces TrueMotion VP3.2 |author=On2 |date=16 August 2000 |access-date=23 August 2010 |archive-url=https://web.archive.org/web/20071203062255/www.on2.com/index.php?id=486&news_id=401 |archive-date=3 December 2007}}</ref> which was the basis for Theora.

===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>

===Theora I specification===
[[File:I-15bis.ogg|thumb|Example of a Theora video used on [[Wikipedia]], showing a [[Polikarpov I-15]] biplane at an aerobatic display.]]
The Theora I bitstream format was [[Freeze (software engineering)|frozen]] in June 2004 after the libtheora 1.0alpha3 release.<ref name="theora-freeze"/> Videos encoded with any version of the libtheora since the alpha3 will be compatible with any future player.<ref name="theora-freeze" /><ref name="theora-news">{{citation
  | title = Theora.org : news | date = 24 September 2009
  | author = Xiph.Org Foundation  | publisher = Xiph.Org Foundation
  | url = https://theora.org/news/ | access-date = 19 May 2025
}}</ref> This is also true for videos encoded with any implementation of the Theora I specification since the format freeze. The ''Theora I Specification'' was completely published in 2004.<ref name="theoraspec-2004">{{Cite web | author=Xiph.Org Foundation | title = Theora I Specification, Xiph.org Foundation, September 17, 2004 | url = http://www.theora.org/doc/Theora_I_spec.pdf  | access-date=26 September 2009 | date = 17 September 2004 |archive-url = https://web.archive.org/web/20040928224506/www.theora.org/doc/Theora_I_spec.pdf |archive-date = 28 September 2004}}</ref> Any later changes in the specification are minor updates.

The Theora reference implementation libtheora spent several years in [[Software release life cycle#Alpha|alpha]] and beta status.<ref name="theora-news" /> The first alpha version was released on 25 September 2002 and the first beta version was released on 22 September 2007.<ref name="CHANGES">{{cite web |title=CHANGES file |url=https://gitlab.xiph.org/xiph/theora/-/blob/master/CHANGES |accessdate=19 May 2025 }}</ref> The first stable release of libtheora was made in November 2008.<ref>{{cite mailing list | url = http://lists.xiph.org/pipermail/theora-dev/2008-November/003736.html | title = Theora 1.0 final release! | mailing-list = theora-dev | date = 3 November 2008 | last = Giles |first = Ralph |access-date=4 November 2008}}</ref><ref>{{cite press release
  | title = The Xiph.Org Foundation announces the release of Theora 1.0
  | publisher = Xiph.Org Foundation | date = 3 November 2008
  | url = https://www.xiph.org/press/2008/theora-release-1.0/ | access-date = 19 May 2025
}}</ref> Work then focused on improving the codec's performance in the ''"Thusnelda"'' branch, which was released as version 1.1 in September 2009 as the second stable libtheora release.<ref name="theora-news" /><ref>{{cite mailing list | url = https://lists.xiph.org/pipermail/theora-dev/2009-September/003985.html | title = libtheora 1.1 (Thusnelda) stable release | mailing-list = theora-dev | date = 24 September 2009 | last = Giles |first = Ralph |access-date=19 May 2025}}</ref> This release brought some technical improvements and new features, such as the new rate control module and the [[two-pass encoding|two-pass rate control]].

The codename for the next version of libtheora was ''Ptalarbvorm''.<ref name="ptalarbvorm">{{Cite web | author=Monty | title = Theora: Ptalarbvorm project update 20100518 | url = http://people.xiph.org/~xiphmont/demo/theora/demo9.html | access-date=1 July 2010 | date = 18 May 2010 }}</ref>

Theora was well established as a video format in [[open-source software|open-source applications]], and became the format used for [[Wikipedia]]'s video content before replaced by [[VP9]]. However, the proposed adoption of Theora as part of the baseline video support in HTML5 [[Use of Ogg formats in HTML5|resulted in controversy]].<ref>{{cite web
  | last = McLean | first = Prince | title = Ogg Theora, H.264 and the HTML 5 Browser Squabble
  | publisher = AppleInsider | date = 7 July 2009
  | url = https://appleinsider.com/articles/09/07/07/ogg_theora_h_264_and_the_html_5_browser_squabble | access-date = 1 November 2020
}}</ref>

=== Legacy ===
In October 2023, Google announced intent to remove Theora support from Chromium<ref>{{Cite web |last=Larabel |first=Michael |date=2023-10-29 |title=Google Chrome To Remove Theora Video Codec Support |url=https://www.phoronix.com/news/Google-Chrome-Dropping-Theora |access-date=2023-11-01 |website=Phoronix |language=en}}</ref> (finalizing removal by Google Chrome 123<ref>{{Cite web |title=Chromium |url=https://issues.chromium.org/issues/40074010 |access-date=2025-09-08 |website=issues.chromium.org}}</ref>), with Firefox following suit.<ref>{{Cite web |title=1860492 - Investigate removing Theora support |url=https://bugzilla.mozilla.org/show_bug.cgi?id=1860492 |access-date=2025-09-08 |website=bugzilla.mozilla.org |language=en}}</ref> Google developers claimed that despite lack of adoption, Theora made a case for open and royalty-free codecs like [[AV1]].<ref>{{Cite web |title=Intent to Ship: Deprecate and remove Theora support. |url=https://groups.google.com/a/chromium.org/g/blink-dev/c/qqDdLkeyk7Y/m/ajHePzglAwAJ |access-date=2023-11-01 |website=groups.google.com}}</ref>{{Better source needed|reason=The current source is primary ([[WP:NOTRS]]).|date=November 2023}}

==Performance==
===Encoding performance===
Evaluations of the VP3<ref>{{cite web | publisher = [[Doom9]] | title = MPEG-4 Codec shoot-out 2002 – 1st installment | year = 2002 | url = https://www.doom9.org/codec-comparisons.htm | access-date = 19 May 2025 | url-status = dead | archive-url = https://web.archive.org/web/20080223010804/http://www.doom9.org/codec-comparisons.htm | archive-date = 23 February 2008 }}</ref>
and early Theora encoders<ref>{{citation | publisher = [[Doom9]] | title = Codec shoot-out 2005 – Qualification | year = 2005 | url = https://www.doom9.org/index.html?/codecs-quali-105-3.htm | access-date = 19 December 2007 | url-status = dead | archive-url = https://web.archive.org/web/20071231133347/www.doom9.org/codecs-quali-105-3.htm | archive-date = 31 December 2007 }}</ref><ref>{{cite web
  | publisher = [[OSNews]] | first = Eugenia | last = Loli-Queru | title = Theora vs. h.264
  | date=12 December 2007 | url = https://www.osnews.com/story/19019/theora-vs-h264/ | access-date =19 May 2025 }}</ref><ref>{{cite web | last = Halbach, Till | title = Dirac and Theora vs. H.264 and Motion JPEG2000 | date = March 2009 | url = http://etill.net/projects/dirac_theora_evaluation/ | access-date = 22 April 2008 | url-status = dead | archive-url = https://archive.today/20120707194336/etill.net/projects/dirac_theora_evaluation/ | archive-date = 7 July 2012 }}</ref>
found that their subjective visual quality was inferior to that of contemporary video codecs. The performance characteristics of the Theora 1.0 reference implementation are dominated mostly by implementation problems inherited from the original VP3 code base.<ref>{{cite web
  | last = Montgomery | first = Chris
  | title = Theora "the push for 1.0" update
  | url = http://web.mit.edu/xiphmont/Public/theora/demo.html | access-date =19 December 2007
}}</ref> Work that lead up to the 1.1 stable release focused on improving on or eliminating these. A May 2009 review of this work by Xiph developer Chris Montgomery claimed a considerable improvement in quality, both subjectively and as measured by [[PSNR]], by improving the forward [[Discrete cosine transform|DCT]] and quantisation matrices.<ref>{{cite web
  | last = Blizzard |first = Christopher
  | title = Theora Update 7 May 2009
  | url = http://web.mit.edu/xiphmont/Public/theora/demo7.html | access-date =10 May 2009
}}</ref>  More recently however,{{when|date=June 2021}} Xiph developers compared the 1.1 Theora encoder to [[YouTube]]'s H.264 and [[H.263+]] encoders, in response to concerns raised in 2009 about Theora's inferior performance by [[Chris DiBona]], a [[Google]] employee.<ref>{{cite mailing list
  | last = DiBona |first = Chris
  | title = H.264-in-&lt;video&gt; vs plugin APIs | mailing-list = whatwg | date = 13 June 2009
  | url = https://lists.whatwg.org/pipermail/whatwg-whatwg.org/2009-June/020380.html | access-date =19 May 2025
}}</ref> They found the results from Theora to be nearly the same as YouTube's H.264 output, and much better than the H.263+ output.<ref>{{cite web | last = Maxwell | first = Greg | title = YouTube / Ogg/Theora comparison | publisher = Xiph.Org Foundation | date = 13 June 2009 | url = http://people.xiph.org/~greg/video/ytcompare/comparison.html | access-date = 10 August 2009 | archive-date = 9 July 2009 | archive-url = https://web.archive.org/web/20090709062345/http://people.xiph.org//~greg//video//ytcompare//comparison.html | url-status = dead }}</ref><ref>{{cite web | last = Merten | first = Maik | title = Another online-video comparison | publisher = Xiph.Org Foundation | date = 15 June 2009 | url = http://people.xiph.org/~maikmerten/youtube/ | access-date = 10 August 2009 | archive-date = 9 July 2009 | archive-url = https://web.archive.org/web/20090709062338/http://people.xiph.org//~maikmerten//youtube// | url-status = dead }}</ref>

The differences in quality, bitrate and file size between a YouTube H.264 video and a transcoded Ogg video file are very small.<ref>{{cite web |last=Blizzard |first=Christopher |date=15 June 2009 |title=open video codecs and quality |url=http://hacks.stage.mozilla.com/2009/06/open-video-codecs-and-quality/ |website=hacks.mozilla.org |url-status=dead |archive-url=https://web.archive.org/web/20100225141300/http://hacks.stage.mozilla.com/2009/06/open-video-codecs-and-quality/ |archive-date=25 February 2010 |access-date=24 August 2025}}</ref>

===Playback performance===
There was an [[open-source software|open-source]] [[VHDL]] code base for a hardware Theora decoder in development.<ref>{{cite web | url = http://svn.xiph.org/trunk/theora-fpga/ | publisher = Xiph.Org Foundation | title = Xiph Subversion repository: trunk/theora-fpga | access-date =10 August 2009 }}</ref>{{update inline|date=June 2021}} It began as a 2006 [[Google]] [[Summer of Code]] project, and it has been developed on both the [[Nios II]] and [[LEON]] processors.<ref>{{cite web | url = https://wiki.xiph.org/Theora_Hardware | title = XiphWiki: Theora Hardware | access-date =10 August 2009 | publisher = Xiph.Org Foundation }}</ref> However, there are no Theora decoder chips in production, and [[portable media player]]s, [[smartphone]]s and similar devices with limited computing power rely on such chips to provide efficient playback.{{citation needed|date=June 2025}}

==Playback==
{{cleanup list|section|date=June 2014}}

===Web browsers===
{{Main|Use of Ogg formats in HTML5}}
As originally recommended by [[HTML 5]], these browsers support Theora when embedded by the <code>video</code> element:

* [[Mozilla Firefox 3.5]] and later versions<ref name="gecko191">{{citation  | title = Firefox3.5/Features | date = 18 March 2009  | author = MozillaWiki  | publisher = MozillaWiki  | url = https://wiki.mozilla.org/Firefox3.5/Features | access-date =11 October 2009}}</ref><ref name="firefox35">{{citation  | title = Mozilla Firefox 3.5 Release Notes | date = 30 June 2009  | author = Mozilla Corporation  | publisher = Mozilla Corporation  | url = https://www.mozilla.com/en-US/firefox/3.5/releasenotes/ | access-date =11 October 2009}}</ref> including [[Firefox for mobile]] (Fennec).<ref name="firefox_mobile">{{citation | title = Firefox Mobile Features | date = 9 February 2010 | author = Mozilla Corporation | publisher = Mozilla Corporation | url = http://www.mozilla.com/en-US/mobile/features/#cutting-edge | access-date =9 February 2010}}</ref> Theora was disabled by default in Firefox 126,<ref>{{Cite web |title=Firefox 126 for developers |url=https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/126 |access-date=2025-01-21 |website=developer.mozilla.org |language=en}}</ref> and support may be removed in the future due to low usage.<ref>{{Cite web |title=Mozilla Eyes Removal Of Theora Support In Firefox |url=https://www.phoronix.com/news/Mozilla-Eyes-Dropping-Theora |access-date=2023-11-01 |website=www.phoronix.com |language=en}}</ref><ref>{{Cite web |title=1860492 – Investigate removing Theora support |url=https://bugzilla.mozilla.org/show_bug.cgi?id=1860492 |access-date=2023-11-01 |website=bugzilla.mozilla.org |language=en}}</ref>
* [[Google Chrome]] as of version 3.0.182.2<ref name="chrome3">{{citation | title = Google Chrome to support HTML 5 video | date = 28 May 2009 | publisher = SoftSailor | url = http://www.softsailor.com/news/3787-3787.html | access-date = 11 October 2009 | url-status = dead | archive-url = https://web.archive.org/web/20091003194653/www.softsailor.com/news/3787-3787.html | archive-date = 3 October 2009 }}</ref><ref name="chrome3-video-cnet">{{citation  | title = Google Chrome gets HTML video support | date = 28 May 2009  | last = Shankland  | first = Stephen  | publisher = cnet news  | url = https://www.cnet.com/tech/services-and-software/google-chrome-gets-html-video-support/ | access-date =19 May 2025 | archive-url = https://web.archive.org/web/20230821213420/https://www.cnet.com/tech/services-and-software/google-chrome-gets-html-video-support/ | archive-date = 21 August 2023}}</ref> including [[Chromium (web browser)|Chromium]] as of 14 July 2009.<ref name="chromium">{{citation  | title =  Issue 16657: Ensure FFmpeg binaries end up in snapshots on all platforms | date = 14 July 2009 | publisher = Google Chromium | url = https://code.google.com/p/chromium/issues/detail?id=16657 | access-date =6 February 2010}}</ref> Chrome 120 disabled support for Theora by default<ref>{{Cite web |last=Larabel |first=Michael |date=2023-12-07 |title=Chrome 120 Released With Theora Support Evaporating, Adds WebGPU & CSS Improvements |url=https://www.phoronix.com/news/Google-Chrome-120 |access-date=2023-12-09 |website=www.phoronix.com |language=en}}</ref> and the complete removal is expected in version 123.<ref>{{Cite web |title=Deprecate and remove Theora support. – Chrome Platform Status |url=https://chromestatus.com/feature/5158654475239424 |access-date=2023-10-24 |website=chromestatus.com}}</ref>
*[[Tizen]] browser
* [[SeaMonkey]] as of version 2.0.<ref name="seamonkey2">{{citation  | title = What's New in SeaMonkey 2.0 Beta 2 | date = 16 September 2009  | last = Kaiser  | first = Robert  | publisher = seamonkey-project.org  | url = https://www.seamonkey-project.org/releases/seamonkey2.0b2/changes | access-date =19 May 2025}}</ref>
* [[Konqueror]] 4.4.2<ref name="konqueror">{{citation |title=Bugreport: Wish for audio/video element support in Konqueror |date=13 May 2007 |url=https://bugs.kde.org/show_bug.cgi?id=145380 |access-date=2 December 2009 |url-status=dead |archive-url=https://archive.today/20121228020255/https://bugs.kde.org/show_bug.cgi?id=145380 |archive-date=28 December 2012 }}</ref><ref name="konqueror44">{{citation |title=Plans for Konqueror 4.4 |date=26 November 2009 |url=http://forum.kde.org/viewtopic.php?f=18&t=83851 |access-date=2 December 2009 |archive-date=17 July 2011 |archive-url=https://web.archive.org/web/20110717175111/forum.kde.org/viewtopic.php?f=18&t=83851 |url-status=dead }}</ref>
* [[Opera (web browser)|Opera]] as of version [[Opera 10#10.50|10.50]].<ref>{{cite web |url=http://my.opera.com/core/blog/2009/12/31/re-introducing-video |title=(re-)Introducing &lt;video&gt; – Official blog for Core developers at Opera |last=Jägenstedt |first=Philip |publisher=Opera |date=31 December 2009 |access-date=2 January 2010|archive-url=https://web.archive.org/web/20100104205648/my.opera.com/core/blog/2009/12/31/re-introducing-video|archive-date=4 January 2010}}</ref><ref>{{cite web |url=http://my.opera.com/desktopteam/blog/happy-new-year |title=Happy New Year! – Official blog for Core developers at Opera |author=Arjan van Leeuwen |publisher=Opera |date=31 December 2009 |access-date=2 January 2010|archive-url=https://web.archive.org/web/20100104201911/my.opera.com/desktopteam/blog/happy-new-year|archive-date=4 January 2010}}</ref> It was also supported in [[History of the Opera web browser#Version 9.5|Opera 9.5]] experimental video builds.<ref name="opera">{{citation  | title = Experimental Opera-video build with native Ogg Theora support | date = 25 April 2007  | publisher = Opera | url = http://my.opera.com/ResearchWizard/blog/experimental-opera-video-build-with-native-ogg-theora-support | access-date =11 October 2009|archive-url=https://web.archive.org/web/20071202032052/my.opera.com/ResearchWizard/blog/experimental-opera-video-build-with-native-ogg-theora-support|archive-date=2 December 2007}}</ref><ref name="opera-dev">{{citation  | title = A call for video on the web – Opera &lt;video&gt; release on Labs | date = 7 November 2007  | publisher = Opera | url = http://dev.opera.com/articles/view/a-call-for-video-on-the-web-opera-vid/ | access-date =11 October 2009}}</ref>  Stopped supporting Theora after version 107.
* [[GNOME Web]] uses WebKitGTK+ as its rendering engine. As WebKitGTK+ uses [[GStreamer]] to implement the HTML5 media player, and all the formats GStreamer supports (including Theora) are available in browser.
* [[Midori (web browser)|Midori]] is another example of a browser that supports Theora by using WebKitGTK+.

===Supporting media frameworks===
* [[DirectShow]] with use of [[OpenCodecs]]
* [[GStreamer]] supported via Theora or FFmpeg module, supports [[:Category:Software that uses GStreamer|GStreamer based applications]] e.g. [[Totem (media player)|Totem]] and [[Songbird (software)|Songbird]]
* [[Phonon (KDE)|Phonon]]
* [[QuickTime]] (including but not limited to Safari) with use of [[Xiph QuickTime Components]]

===Supporting applications===
* [[FFmpeg]] (own implementation)
* [[Helix project|Helix Player]]
* [[Miro Media Player]] (formerly known as [[Democracy Player]])
* [[MPlayer]] and front-ends
* [[Totem (media player)|Totem]], [[Moovida]] and all [[GStreamer]]-based players
* [[VLC media player|VLC]] (native support)
* [[xine]] and all libxine-based players like [[Kaffeine]]
* [[Dragon Player]] and all Phonon-based players

==Encoding==
There are several third-party programs that support encoding through libtheora:

{| style="text-align: center;" class="wikitable"
! rowspan="2" | Name
! rowspan="2" | Description
! colspan="3" | Operating Systems Supported
|-
| style="width: 10%;" | Unix-like
| style="width: 10%;" | OS X
| style="width: 10%;" | Windows
|-
| style="text-align: left;" |
; [[ffmpeg2theora]]<ref>{{Cite web|url=http://v2v.cc/~j/ffmpeg2theora/|title=ffmpeg2theora|website=v2v.cc|access-date=2 June 2009|archive-date=11 March 2008|archive-url=https://web.archive.org/web/20080311021714/v2v.cc/~j/ffmpeg2theora/|url-status=dead}}</ref>
| style="text-align: left;" | A command-line program that transcodes video by decoding with [[FFmpeg]] and reencoding with libtheora to encode it
| {{yes}}
| {{yes}}
| {{yes}}
|-
| style="text-align: left;" |
; [[VLC media player|VLC]]
| style="text-align: left;" | Can transcode to single-pass Theora 1.0 and optionally stream it
| {{yes}}
| {{yes}}
| {{yes}}
|-
| style="text-align: left;" |
; [[FreeJ]]
| style="text-align: left;" | "Video DJing" software that can encode to and stream Theora
| {{yes}}
| {{yes}}
| ?
|-
| style="text-align: left;" |
; [[Kdenlive]]
| style="text-align: left;" | The video editor supplied with [[KDE]]
| {{yes}}
| ?
| ?
|-
| style="text-align: left;" |
; [[Pitivi]]
| style="text-align: left;" | The video editor supplied with [[GNOME]]
| {{yes}}
| ?
| ?
|-
| style="text-align: left;" |
; [[LiVES]]
| style="text-align: left;" | Video editing software for Linux. Can edit, encode and stream theora.
| {{yes}}
| {{yes}}
| ?
|-
| style="text-align: left;" |
; [[HandBrake]]
| style="text-align: left;" | Can output to Theora only with the [[Matroska]] container
| {{yes}}
| {{yes}}
| {{yes}}
|-
| style="text-align: left;" |
; [[RecordMyDesktop]]
| style="text-align: left;" | Records the screen to Ogg Theora with optional Vorbis audio
| {{yes}}
| ?
| ?
|}

The libtheora library contains the reference implementation of the Theora specification for encoding and decoding. libtheora was developed by the [[Xiph.Org Foundation]]. The library was released under the terms of a [[BSD licenses|BSD-style license]].

Also, several media frameworks have support for Theora.

* The open-source [[ffdshow]] audio/video decoder is capable of encoding Theora videos using its [[Video for Windows]] (VFW) multi-codec interface within popular AVI editing programs.<ref>{{cite web | url=https://sourceforge.net/projects/ffdshow-tryout/ | title=ffdshow Summary | date=10 March 2019 | access-date=19 May 2025}}</ref><ref>{{Cite mailing list | url=http://lists.xiph.org/pipermail/theora-dev/2002-October/001329.html | date=4 October 2002 | title=Theora support in ffdshow a ffvfw | mailing-list=theora-dev | last=Cutka | first=Milan}}</ref><ref>{{cite web | url=https://ffdshow-tryout.sourceforge.net/phpBB2/viewtopic.php?p=2459&sid=6a8a488dd3aebb9e35764e950de65d60 | title=Theora in .ogg no only .avi – ffdshow tryouts Forum | date=15 January 2008 | access-date=23 October 2009}}</ref> It supports both encoding and decoding Theora video streams and uses Theora's alpha 4 libraries. However, many of the more refined features of Theora are not available to the user in ffdshow's interface.
* The [[GStreamer]] framework has support for parsing raw Theora streams, encoding and decoding raw Theora streams to/from YUV video<ref>{{cite web | url=https://gstreamer.freedesktop.org/documentation/theora/index.html?gi-language=c | title=theora | author=gstreamer.freedesktop.org  | access-date=19 May 2025}}</ref><ref>{{cite web | url=https://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-plugins/html/gst-plugins-base-plugins-plugin-theora.html | title=GStreamer Base Plugins 0.10 Plugins Reference Manual – Theora plugin library | author=gstreamer.freedesktop.org  | access-date=23 October 2009}}</ref>

==Editing==
{| style="text-align: center;" class="wikitable"
! rowspan="2" | Name
! rowspan="2" | Description
! colspan="3" | Operating Systems Supported
|-
| style="width: 10%;" | Unix-like
| style="width: 10%;" | OS X
| style="width: 10%;" | Windows
|-
| style="text-align: left;" |
; [[LiVES]]
| style="text-align: left;" | Video editing software for Linux. Can edit, encode and stream theora.
| {{yes}}
| {{yes}}
| ?
|-
| style="text-align: left;" |
; [[Kdenlive]]
| style="text-align: left;" | The [[KDE]] video editor.
| {{yes}}
| ?
| ?
|-
| style="text-align: left;" |
; [[OpenShot Video Editor|OpenShot]]
|
| {{yes}}
| ?
| ?
|-
| style="text-align: left;" |
; [[Pitivi]]
| style="text-align: left;" | The [[GNOME]] video editor.
| {{yes}}
| ?
| ?
|-
| style="text-align: left;" |
; [[Cinelerra]]
| style="text-align: left;" | [[Concurrent Versions System|CVS]] versions of the [[Cinelerra]] [[Non-linear editing system|non-linear video editing system]] support Theora, as of August 2005.
| {{yes}}
| {{yes}}
| ?
|-
| style="text-align: left;" |
; oggz-tools by [[Xiph.org]]
| style="text-align: left;" | Command line programs to examine and edit Ogg files.
| {{yes}}
| ?
| {{yes}}
|-
| style="text-align: left;" |
; Ogg Video Tools by yornstreamnik
| style="text-align: left;" | Tools to resize, cut, split, join, and others<ref>{{Cite web |title=Ogg Video Tools - Browse Files at SourceForge.net |url=https://sourceforge.net/projects/oggvideotools/files/ |access-date=2022-11-06 |website=sourceforge.net}}</ref>
| {{yes}}
| {{yes}}
| {{yes}}
|-
| style="text-align: left;" |
; [[AVS Video Editor]]
|
| ?
| ?
| {{yes}}
|}

==Streaming==
The following streaming media servers are capable of streaming Theora video:

{| style="text-align: center;" class="wikitable"
! rowspan="2" | Name
! rowspan="2" | Description
! colspan="3" | Operating Systems Supported
|-
| style="width: 10%;" | Unix-like
| style="width: 10%;" | OS X
| style="width: 10%;" | Windows
|-
| style="text-align: left;" |
; [[VLC media player|VLC]]
|
| {{yes}}
| {{yes}}
| {{yes}}
|-
| style="text-align: left;" |
; [[Icecast]]
|
| {{yes}}
| ?
| {{yes}}
|-
| style="text-align: left;" |
; [[LiVES]]
| style="text-align: left;" | Can stream ogg/theora/vorbis in realtime to a file or fifo.
| {{yes}}
| {{yes}}
| ?
|-
|}

== Makers ==
[[Elphel]] is the main maker of cameras that record in theora.

==See also==
{{Portal|Free and open-source software}}
* [[AV1|AV1 (open and royalty-free video coding format)]]
* [[Comparison of video codecs]]
* [[Dirac (video compression format)]]
* [[FFV1|FFV1 (Lossless intra-frame video coding format)]]
* [[Video editing software]]

==References==
{{Reflist}}

==External links==
* {{Official website|https://www.theora.org/}}
<!--  Theora.org :: main - Theora, video for everyone -->
* [https://wiki.xiph.org/Theora main Theora page of the official Xiph.Org wiki]
* [https://wiki.xiph.org/index.php/List_of_Theora_videos Examples of Theora-encoded videos]
* [https://maketelevision.com/log/why_ogg_theora_matters_for_internet_tv Why Theora Matters for Internet TV]
* [https://archive.flossmanuals.net/ogg-theora/ Ogg Theora Cook Book on FLOSS Manuals]
* [http://svn.xiph.org/trunk/theora/doc/draft-ietf-avt-rtp-theora-00.txt RTP Payload Format for Theora Encoded Video – Xiph.Org]
* [https://datatracker.ietf.org/doc/html/draft-barbato-avt-rtp-theora-01 draft-barbato-avt-rtp-theora-01 RTP Payload Format for Theora Encoded Video IETF Internet Draft]
* [https://compression.ru/compression.ru/video/codec_comparison/h264_2010/ H.264 and Theora codecs comparison]

{{Compression formats}}
{{Compression software}}
{{Media player (application software)|free}}
{{Xiph.org}}

[[Category:Articles containing video clips]]
[[Category:Free video codecs]]
[[Category:Open formats]]
[[Category:Software using the BSD license]]
[[Category:Xiph.Org projects]]