Theora

Theora is a variable-bitrate, DCT-based video compression scheme. Like most common video codecs, Theora used chroma subsampling, 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 bi-predictive frames which are found in H.264 and VC-1. Theora also does not support interlacing, or bit-depths larger than 8 bits per component.

Theora video streams can be stored in any suitable 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.{{cite web |title=Matroska Codec Specs |url=https://www.matroska.org/technical/codec_specs.html |access-date=19 May 2025 |publisher=Matroska}}

The Theora video-compression format is compatible with the VP3 video-compression format, which consisted of a backward-compatible superset.Xiph.org [https://theora.org/faq/#VP3 FAQ – Theora and VP3]. Retrieved 2 September 2009 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). VP3 video compression can be decoded using Theora implementations, but Theora video compression usually cannot be decoded using old VP3 implementations.

{{See also|VP3}}

Theora's predecessor On2 TrueMotion VP3 was originally a proprietary and patent-encumbered video codec developed by On2 Technologies. VP3.1 was introduced in May 2000{{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}} and followed three months later by the VP3.2 release,{{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}} which was the basis for Theora.

In August 2001, On2 Technologies announced that they would release an open source version of their VP3.2 video compression algorithm.{{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}}{{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}} In September 2001, On2 Technologies published the source code of the VP3.2 codec under the VP3.2 Public License 0.1,{{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

}} a custom open-source license.{{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}}{{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}} The license only granted the right to modify the source code if the resultant larger work continued to support playback of VP3.2 data.{{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}}

In March 2002, On2 responded to the public's reception by relicensing the VP3 codec under the GNU Lesser General Public License.{{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 }} In June 2002, On2 donated VP3 to the Xiph.Org Foundation and offered it under the Ogg Vorbis BSD-style license.{{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}}{{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}}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 2009-08-16InternetNews.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 On2 also made an irrevocable, royalty-free license grant for any patent claims it might have over the software and any derivatives, allowing anyone to use any VP3-derived codec for any purpose.Xiph.org [http://svn.xiph.org/trunk/theora/LICENSE libtheora license (Subversion – Trunk)], Retrieved on 16 August 2009Xiph.org [http://svn.xiph.org/trunk/vp32/LICENSE VP32 codec license (Subversion – Trunk)], Retrieved on 16 August 2009 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.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 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.{{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}}

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.{{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

}}

A successor to Theora, Daala, was later merged into AV1.{{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}}

File:I-15bis.ogg, showing a Polikarpov I-15 biplane at an aerobatic display.]]

The Theora I bitstream format was frozen in June 2004 after the libtheora 1.0alpha3 release. Videos encoded with any version of the libtheora since the alpha3 will be compatible with any future player.{{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

}} 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.{{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}} Any later changes in the specification are minor updates.

The Theora reference implementation libtheora spent several years in alpha and beta status. The first alpha version was released on 25 September 2002 and the first beta version was released on 22 September 2007.{{cite web |title=CHANGES file |url=https://gitlab.xiph.org/xiph/theora/-/blob/master/CHANGES |accessdate=19 May 2025 }} The first stable release of libtheora was made in November 2008.{{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}}{{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

}} 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.{{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}} This release brought some technical improvements and new features, such as the new rate control module and the two-pass rate control.

The codename for the next version of libtheora was 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 }}

Theora was well established as a video format in 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 resulted in controversy.{{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

}}

In October 2023, Google announced intent to remove Theora support from Chromium (finalizing removal by Google Chrome 123),{{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}} with Firefox following suit. Google developers claimed that despite lack of adoption, Theora made a case for open and royalty-free codecs like AV1.{{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}}{{Better source needed|reason=The current source is primary (WP:NOTRS).|date=November 2023}}

Evaluations of the VP3{{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 }}

and early Theora encoders{{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 }}{{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 }}{{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 }}

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.{{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

}} 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 DCT and quantisation matrices.{{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

}} 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.{{cite mailing list

| last = DiBona |first = Chris

| title = H.264-in-<video> 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

}} 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.{{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 }}{{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 }}

The differences in quality, bitrate and file size between a YouTube H.264 video and a transcoded Ogg video file are very small.{{cite web

| last = Richmond |first = Gary

| title = Firefogg: Transcoding videos to open web standards with Mozilla Firefox

| url = http://freesoftwaremagazine.com/articles/firefogg_transcoding_videos_open_web_standards_mozilla_firefox/ | access-date =19 May 2025

}}

There was an open-source VHDL code base for a hardware Theora decoder in development.{{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 }}{{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.{{cite web | url = https://wiki.xiph.org/Theora_Hardware | title = XiphWiki: Theora Hardware | access-date =10 August 2009 | publisher = Xiph.Org Foundation }} However, there are currently no Theora decoder chips in production, and portable media players, smartphones and similar devices with limited computing power rely on such chips to provide efficient playback.

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

{{Main|Use of Ogg formats in HTML5}}

As originally recommended by HTML 5, these browsers support Theora when embedded by the video element:

• Mozilla Firefox 3.5 and later versions{{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}}{{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}} including Firefox for mobile (Fennec).{{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}} Theora was disabled by default in Firefox 126,{{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}} and support may be removed in the future due to low usage.{{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}}{{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}}
• Google Chrome as of version 3.0.182.2{{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 }}{{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}} including Chromium as of 14 July 2009.{{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}} Chrome 120 disabled support for Theora by default{{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}} and the complete removal is expected in version 123.{{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}}
• Tizen browser
• SeaMonkey as of version 2.0.{{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}}
• Konqueror 4.4.2{{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 }}{{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 }}
• Opera as of version 10.50.{{cite web |url=http://my.opera.com/core/blog/2009/12/31/re-introducing-video |title=(re-)Introducing <video> – 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}}{{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}} It was also supported in Opera 9.5 experimental video builds.{{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}}{{citation | title = A call for video on the web – Opera <video> 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}} 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 is another example of a browser that supports Theora by using WebKitGTK+.

• DirectShow with use of OpenCodecs
• GStreamer supported via Theora or FFmpeg module, supports GStreamer based applications e.g. Totem and Songbird
• Phonon
• QuickTime (including but not limited to Safari) with use of Xiph QuickTime Components

• FFmpeg (own implementation)
• Helix Player
• Miro Media Player (formerly known as Democracy Player)
• MPlayer and front-ends
• Totem, Moovida and all GStreamer-based players
• VLC (native support)
• xine and all libxine-based players like Kaffeine
• Dragon Player and all Phonon-based players

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

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-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.{{cite web | url=https://sourceforge.net/projects/ffdshow-tryout/ | title=ffdshow Summary | date=10 March 2019 | access-date=19 May 2025}}{{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}}{{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}} 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{{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}}{{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}}

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

Elphel is the main maker of cameras that record in theora.

{{Portal|Free and open-source software}}

• AV1 (open and royalty-free video coding format)
• Comparison of video codecs
• Dirac (video compression format)
• FFV1 (Lossless intra-frame video coding format)
• Video editing software

{{Reflist}}

• {{Official website|https://www.theora.org/}}

• [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}}

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