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Theora
File name extension. A filename extension is a suffix to the name of a Computer file applied to indicate the encoding convention ( File format) of its contents ogv (was . ogg in the past)
Internet media typevideo/ogg
Developed byXiph.Org Foundation
Type of formatVideo codec
Contained byOgg
Extended fromVP3

Theora is an open and royalty-free lossy video compression technology being developed by the Xiph.Org Foundation as part of their Ogg project. An Internet media type, originally called a MIME type after MIME and sometimes a Content-type after the name of a header in several protocols whose value A video Codec is a device or Software that enables Video compression and/or decompression for digital video To learn how to create video or audio files for Wikipedia and its sister projects check WikipediaCreation and usage of media files. A lossy compression method is one where compressing data and then decompressing it retrieves data that may well be different from the original but is close enough to be useful Video compression refers to reducing the quantity of Data used to represent video images and is a straightforward combination of Image compression and Motion The XiphOrg Foundation is a 501(c(3 Non-profit organization dedicated to producing free Multimedia formats and tools To learn how to create video or audio files for Wikipedia and its sister projects check WikipediaCreation and usage of media files. Based upon On2 Technologies' VP3 codec, Theora is targeted at competing with MPEG-4, WMV, and similar low-bitrate video compression schemes. On2 Technologies ( formerly known as The Duck Corporation, is a small publicly-traded company (on the American Stock Exchange) headquartered in Tarrytown MPEG-4 is a collection of methods defining compression of audio and visual (AV digital data Windows Media Video ( WMV) is a compressed Video file format for several proprietary Codecs developed by Microsoft.

Theora is named for Theora Jones, Edison Carter's Controller on the Max Headroom television program. Max Headroom (1987 – 1988 was a short-lived but ground-breaking American Science fiction Television series which aired on ABC. Max Headroom (1987 – 1988 was a short-lived but ground-breaking American Science fiction Television series which aired on ABC. Max Headroom (1987 – 1988 was a short-lived but ground-breaking American Science fiction Television series which aired on ABC.

Contents

Technical details

Theora is a lossy video compression method derived from On2's VP3 Codec. A lossy compression method is one where compressing data and then decompressing it retrieves data that may well be different from the original but is close enough to be useful On2 Technologies ( formerly known as The Duck Corporation, is a small publicly-traded company (on the American Stock Exchange) headquartered in Tarrytown The compressed video can be stored in any suitable container format. A container format is a computer file format that can contain various types of data compressed by means of standardized audio/video codecs. At the time of writing (June 2006), Theora video is generally included in Ogg container format. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. To learn how to create video or audio files for Wikipedia and its sister projects check WikipediaCreation and usage of media files. It is frequently paired with Vorbis audio. Vorbis is a free and open source, lossy audio Codec project headed by the Xiph

The combination of the Ogg container format, Theora video and Vorbis audio allows for a completely open, royalty-free multimedia format. To learn how to create video or audio files for Wikipedia and its sister projects check WikipediaCreation and usage of media files. Vorbis is a free and open source, lossy audio Codec project headed by the Xiph Other multimedia formats, such as MPEG-4 video and MP3 audio, are patented and subject to license fees for commercial use.

Like many other image and video formats, Theora uses Chroma subsampling, block based motion compensation and an 8×8 DCT block. Chroma subsampling is the practice of encoding images by implementing less resolution for chroma Information than for luma information A discrete cosine transform ( DCT) expresses a sequence of finitely many data points in terms of a sum of Cosine functions oscillating at different frequencies This is comparable to MPEG-1/2/4. MPEG-1 was an early Standard for Lossy compression of Video and audio. MPEG-2 is a standard for "the generic coding of moving pictures and associated audio information" MPEG-4 Part 2 is a Video compression technology developed by MPEG. It supports intra coded frames and forward predictive frames but not bi-predictive frames that can be found in many other video codecs. I-frame redirects here For the HTML-element see IFrame. The three major picture types found in typical Video compression designs are [1]

VP3

VP3 was originally a proprietary and patented video codec developed by On2 Technologies. Proprietary software is Computer software on which the producer has set restrictions on use private modification copying, or republishing. A video Codec is a device or Software that enables Video compression and/or decompression for digital video On2 Technologies ( formerly known as The Duck Corporation, is a small publicly-traded company (on the American Stock Exchange) headquartered in Tarrytown In September, 2001 VP3 was donated to the public as free and open source software, and On2 disclaimed all rights to it, including their patents on the technology, letting anyone use Theora and other VP3-derived codecs for any purpose. Year 2001 ( MMI) was a Common year starting on Monday according to the Gregorian calendar. Free software or software libre is Software that can be used studied and modified without restriction and which can be copied and redistributed in modified or unmodified Open source software (OSS began as a marketing campaign for Free software. A patent is a set of Exclusive rights granted by a State to an inventor or his assignee for a fixed period of time in exchange for a disclosure of an [2] In 2002, On2 entered into an agreement with the Xiph.Org Foundation to make VP3 the basis of a new, free video codec, Theora. See also 2002 (disambiguation Year 2002 ( MMII) was a Common year starting on Tuesday of the Gregorian calendar. The XiphOrg Foundation is a 501(c(3 Non-profit organization dedicated to producing free Multimedia formats and tools On2 christened Theora as the successor in VP3's lineage.

Current status

As of May 2008, Theora is in final beta stage (1. A software release is the distribution whether public or private of an initial or new and upgraded version of a Computer software product 0 beta 3) before the official release of version 1. 0. The bitstream format was frozen with alpha 3 (July 2004), so videos encoded with any version of Theora since that time will continue to be compatible with any future player.

Performance

Previous evaluations have found VP3[3] and Theora[4] [5] substantially lacking compared to contemporary video codecs (having been called comparable in quality and bit rate to H.261,[6] although some dispute this point). H261 is a 1990 ITU-T video coding standard originally designed for transmission over ISDN lines on which data rates are multiples of 64 kbit/s

Efforts to improve performance

Sources close to Xiph. org have stated that the performance characteristics of the current Theora reference implementation are mostly dominated by implementation issues inherited from the original VP3 code base. An internal document exists, which lists the known implementation problems and gives an example of how improving one aspect of the encoder can lead to visibly improved quality. [7] Current work on Theora is focused on an experimental version, which targets correcting aspects of the encoder which were identified in that paper as being suboptimal. This experimental version is supposed to replace the current encoder in a future Theora release.

Playing Theora

See also Wikipedia:Media help (Ogg)

Encoding Theora videos

The libtheora library contains the reference implementations of both the Theora encoder and decoder. Cortado is a streaming Java applet for Ogg formats ( Vorbis, Theora) µ-law, MJPEG and Smoke (a custom MJPEG An applet is a software component that runs in the context of another program for example a Web browser. Cortado is a streaming Java applet for Ogg formats ( Vorbis, Theora) µ-law, MJPEG and Smoke (a custom MJPEG FFmpeg is a computer program that can record convert and stream digital audio and Video in numerous formats MPlayer is a free and Open source media player. The program is available for all major Operating systems including Linux RealPlayer (briefly known also as RealOne Player) is a proprietary Cross-platform media player by RealNetworks that plays a number This article is about the free and open-source software media project xine (officially ksin is a Multimedia playback engine for Unix-like Operating systems released under the GNU General Public License. Kaffeine is a media player for Unix-like Operating systems running KDE. Totem is a Free software media player (audio and video for the GNOME Computer Desktop environment which runs on Linux, QuickTime is a Multimedia framework developed by Apple Inc, capable of handling various formats of Digital video, Media clips sound text Visonair is an Internet TV network created by Crave Create Its aim was to become the first Open Access or Public Access Internet TV based network Miro (previously known as Democracy Player and DTV) is an Internet television application developed by the Participatory Culture Foundation. Miro (previously known as Democracy Player and DTV) is an Internet television application developed by the Participatory Culture Foundation. libtheora is still under development by the Xiph.Org Foundation, which has made eight alpha releases and 3 major beta release thus far which include a complete rewrite of the decoder. The XiphOrg Foundation is a 501(c(3 Non-profit organization dedicated to producing free Multimedia formats and tools A software release is the distribution whether public or private of an initial or new and upgraded version of a Computer software product The library is released under the terms of a BSD-style license. BSD licenses represent a family of Permissive free software licences.

As of 2008, the Xiph. Org Foundation has not developed any stand-alone programs to encode video in Theora, but there are several third-party programs that support encoding through libtheora:

Also, several media frameworks have support for Theora.

Editing Theora videos

CVS versions of the Cinelerra non-linear video editing system support Theora, as of August 2005. In the field of Software development, the Concurrent Versions System ( CVS) also known as the Concurrent Versioning System, provides a Version Cinelerra is a free and Open source software non-linear video editing system "NLE" redirects here For the standardized test see National Latin Examination.

Streaming Theora

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

See also

References

  1. ^ http://theora.org/doc/Theora_I_spec.pdf
  2. ^ VP3.2 Public License 0.1, 2001, <http://trac.xiph.org/browser/branches/vp32/vp32/VP32_license.txt>. Icecast is a free Streaming media project maintained by the Xiph FreeCast is a Free software application which allows Peer-to-peer streaming sometimes called Peercasting. Flumotion SA is a Spanish company based in Barcelona, which has developed a multiformat Streaming platform to publish audio and video content via internet Video editing software is Application software which handles the editing of video sequences on a computer Dirac is a prototype Algorithm for the encoding and decoding of raw video Comparison of Video codecs - is an Evaluation process for codec Similarities and Differences. Retrieved on 10 February 2008 
  3. ^ Doom9 (2002), MPEG-4 Codec shoot-out 2002 - 1st installment, <http://www.doom9.org/codec-comparisons.htm>. Retrieved on 19 December 2007 
  4. ^ Doom9 (2005), Codec shoot-out 2005 - Qualification, <http://www.doom9.org/codecs-quali-105-3.htm>. Retrieved on 19 December 2007 
  5. ^ Loli-Queru, Eugenia (December 12, 2007), Theora vs. h.264, OSNews, <http://ww.osnews.com/story/19019/Theora-vs-h.264/>. Events 627 - Battle of Nineveh: A Byzantine army under Emperor Heraclius defeats Emperor Khosrau II 's Persian Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. OSNews is a Computing news site with a focus on Operating systems and their related technologies that launched in 1997. Retrieved on 1 April 2008 
  6. ^ Wenger, Stephan (December 12, 2007), Web Architecture and Codec Considerations for Audio-Visual Services, pp. Events 627 - Battle of Nineveh: A Byzantine army under Emperor Heraclius defeats Emperor Khosrau II 's Persian Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. 3, <http://www.w3.org/2007/08/video/positions/Nokia.pdf>. Retrieved on 19 December 2007 
  7. ^ Montgomery, Chris, Theora "the push for 1.0" update, <http://web.mit.edu/xiphmont/Public/theora/demo.html>. Retrieved on 19 December 2007 

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