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Information about Theora

Theora
File extension:.ogv
MIME type:video/ogg
Developed by:Xiph.Org Foundation
Type of format:Video codec
Contained by:Ogg
Standard(s):Specification


Theora is a video codec being developed by the Xiph.Org Foundation as part of their Ogg project. Based upon On2 Technologies' VP3 codec, and christened by On2 as the successor in VP3's lineage, Theora is targeted at competing with MPEG-4 video (e.g., the x264, Xvid and DivX codecs), RealVideo, Windows Media Video, and similar lower-bitrate video compression schemes.

While VP3 is patented technology, On2 has irrevocably given royalty-free license of the VP3 patents to everyone, letting anyone use Theora and other VP3-derived codecs for any purpose.

In the Ogg multimedia framework, Theora provides a video layer, while Vorbis usually acts as the audio layer. Speex, FLAC, and OggPCM may also act as audio layers.

Theora is named for Theora Jones, Edison Carter's Controller on the Max Headroom television program.

Technical details

Theora is a lossy video compression method derived from On2's VP3 Codec. The compressed video can be stored in any suitable container format. At the time of writing (June 2006), Theora video is generally included in Ogg container format. It is frequently paired with Vorbis audio.

The combination of the Ogg container format, Theora video and Vorbis audio allows for a completely open, royalty-free multimedia format. 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. Theora uses block based motion compensation and an 8x8 DCT block. This is comparable to MPEG-1/2/4. It supports intra coded frames and forward predictive frames but not bi-predictive frames that can be found in many other video codecs. [1]

VP3

VP3 was originally a proprietary video codec developed by On2 Technologies. It is approximately comparable in quality and bit rate to MPEG-4 video codecs.

In September, 2001 it was donated to the public as open source, and On2 disclaimed all rights to it, including their patents on the technology. In 2002, On2 entered into an agreement with the Xiph.Org Foundation to make VP3 the basis of a new, free video codec, Theora. It can be operated alongside Vorbis to provide a set of open source multimedia codecs that are intended to be free of patent licensing restrictions and royalty fees. Theora is currently in final beta stage before the official release of version 1.0. The bitstream format was frozen with alpha 3, therefore video encoded in current and older versions of Theora is compatible with any player.

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. libtheora is still under development by the Xiph.Org Foundation, which has made eight alpha releases and one beta release thus far. The library is released under the terms of a BSD-style license.

As of 2006, 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:
  • ffmpeg2theora uses FFmpeg to decode video and libtheora to encode it. This is currently the most functional Theora encoder, and can be used for both creating stand-alone video files and to produce streaming video.
  • VLC is able to encode Theora video, from any of the video sources it supports, and also stream it.
  • The open-source OggConvert http://oggconvert.tristanb.net utility can convert virtually all common media formats to Theora.
  • The open-source 'Video DJ' program FreeJ can encode and stream Theora. Video comes from one or more different video or image files/sources while audio is encoded from the soundcard.
  • The GNOME video editor Diva encodes to Theora.
  • The freeware Super program can transcode between Theora and almost any other format.
  • The open-source Video Editing program LiVES can also encode to Theora at different quality settings.
  • There is also currently a beta-version of Thoggen http://thoggen.net/ for Linux, a GTK+ and GStreamer based DVD-backup utility, which encodes to Vorbis and Theora.
  • KungFu DVD Ripper [https://launchpad.net/kungfu]
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 such as VirtualDub. 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 aren't available to the user in ffdshow's interface.
  • The GStreamer framework has support for Theora.

Editing Theora videos

CVS versions of the Cinelerra non-linear video editing system support Theora, as of August 2005.

Streaming Theora

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

See also

External links

1. ^ [1]


 •  • [ e]
Xiph.Org Foundation
Ogg Project
Vorbis • Theora • FLAC • Speex • Tremor • OggUVS • OggPCM
Other projects
XSPF • Annodex • Xiph QuickTime Components • cdparanoia • Icecast • IceShare
Related articles
Chris Montgomery • CMML • Ogg Media • Ogg page • Ogg Squish
 •  • [ e]
Multimedia compression formats
Video compression formats
ISO/IEC
MJPEG MPEG-1 MPEG-2 MPEG-4 ASP MPEG-4/AVC 		ITU-T
H.261 H.262 H.263 H.264 		Others
AVS Bink Dirac Indeo MJPEG RealVideo Theora VC-1 VP6 VP7 WMV
Audio compression formats
ISO/IEC
MPEG-1 Layer III (MP3) MPEG-1 Layer II MPEG-1 Layer I AAC HE-AAC HE-AAC v2 aacPlus v2 		ITU-T
G.711 G.722 G.722.1 G.722.2 G.723 G.723.1 G.726 G.728 G.729 G.729.1 G.729a 		Others
AC3 Apple Lossless ATRAC FLAC iLBC Monkey's Audio μ-law Musepack Nellymoser OptimFROG RealAudio SHN Speex Vorbis WavPack WMA TAK
Image compression formats
ISO/IEC/ITU-T
JPEG JPEG 2000 lossless JPEG JBIG JBIG2 PNG WBMP 		Others
BMP GIF ILBM PCX PGF TGA TIFF HD Photo
Media container formats
General
3GP ASF AVI DMF DPX FLV Matroska MP4 MXF NUT Ogg Ogg Media QuickTime RealMedia VOB 		Audio only
AIFF AU WAV
See for methods and for codecs
A filename extension is a suffix to the name of a computer file applied to indicate its type. It is commonly used to infer information about what sort of data might be stored in the file.
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Mime or pantomime is a theatrical medium or performance art, involving the acting out of a story by a mime artist through body motions, without use of speech.

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A video codec is a device or software that enables video compression and or decompression for digital video. The compression usually employs lossy data compression. Historically, video was stored as an analog signal on magnetic tape.
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Ogg may refer to:
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A codec is a device or program capable of performing encoding and decoding on a digital data stream or signal. The word codec may be a combination of any of the following: 'Compressor-Dec
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Xiph.Org Foundation

Type 501(c)(3) The Xiph.Org Foundation is a 501(c)(3) non-profit organization[1] dedicated to producing free multimedia formats and tools.
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Ogg may refer to:
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On2 Technologies ((AMEX: ONT )), formerly known as The Duck Corporation, is a small publicly-traded company (on the American Stock Exchange) that designs proprietary and standards-based video codec technology.
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MPEG-4 is a standard used primarily to compress audio and visual (AV) digital data. Introduced in late 1998, it is the designation for a group of audio and video coding standards and related technology agreed upon by the ISO/IEC Moving Picture Experts Group (MPEG) under the formal
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Xvid (formerly "XviD") is a video codec library following the MPEG-4 standard. Xvid features MPEG-4 Advanced Simple Profile features such as b-frames, global and quarter pixel motion compensation, lumi masking, trellis quantization, and H.
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DivX are a brand name of products created by DivX, Inc. (formerly DivXNetworks, Inc.), including the DivX Codec which has become popular due to its ability to compress lengthy video segments into small sizes while maintaining relatively high visual quality.
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RealVideo is a proprietary video format developed by RealNetworks. It was first released in 1997 and as of 2006 is at version 10. RealVideo is supported on many platforms, including Windows, Mac, Linux, Solaris, and several mobile phones.
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Windows Media Video

File extension: .wmv
MIME type: video/x-ms-wmv
Uniform Type Identifier: com.microsoft.windows-?media-wmv
Developed by: Microsoft
Type of format: video file format Windows Media Video (WMV
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Vorbis

File extension: .ogg .oga [1]
MIME type: audio/ogg
Developed by: Xiph.Org Foundation
Type of format: Audio codec
Contained by: Ogg
Standard(s): Specification

Vorbis
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Speex

File extension: .spx
Developed by: Xiph.Org Foundation
Type of format: Audio codec
Contained by: Ogg
Standard(s): Specification

Speex is a free software speech codec that may be used on VoIP applications and podcasts.
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Free Lossless Audio Codec

File extension: .flac
MIME type: audio/x-flac[1]
Type of format: Audio
Free Lossless Audio Codec

Developer: Xiph.Org Foundation
Latest release: 1.2.
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Theora Jones is a fictional character on the television show Max Headroom.

Theora was played by Amanda Pays and first appeared in the British-made television pilot film for the series. Along with Matt Frewer and W.
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Edison Carter was one of the main characters in the science fiction television series Max Headroom. A hard-hitting reporter for Network 23, he sometimes came close to uncovering things that his superiors in the network would've preferred to keep private.
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Max Headroom (1987 – 1988) was a short-lived but ground-breaking American science fiction television series which aired on ABC. The series was developed from a British television movie, 20 Minutes into the Future
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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 in some way.
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On2 Technologies ((AMEX: ONT )), formerly known as The Duck Corporation, is a small publicly-traded company (on the American Stock Exchange) that designs proprietary and standards-based video codec technology.
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Ogg may refer to:
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Vorbis

File extension: .ogg .oga [1]
MIME type: audio/ogg
Developed by: Xiph.Org Foundation
Type of format: Audio codec
Contained by: Ogg
Standard(s): Specification

Vorbis
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Ogg may refer to:
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