*** Welcome to piglix ***

Ogg Theora

Theora
Theora logo 2007.svg
Filename extension .ogv, .ogg
Internet media type video/ogg
Developed by Xiph.org
Initial release 1 June 2004 (2004-06-01)
Latest release
Theora I
(16 March 2011)
Type of format Compressed video
Contained by Ogg, Matroska
Extended from VP3
Standard Specification
Open format? Yes
Website theora.org
libtheora
Developer(s) Xiph.org
Initial release 3 November 2008 (2008-11-03) (1.0)
Stable release
1.1.1 / 1 October 2009; 7 years ago (2009-10-01)
Preview release
1.2.0 Alpha 1 / 24 September 2010; 6 years ago (2010-09-24)
Development status Inactive
Written in C
Operating system Unix-like (incl Linux, Mac OS X), Windows
Type Video codec, reference implementation
License 3-clause BSD
Website theora.org

Theora is a free lossy video compression format. It is 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 of the Theora video compression format being developed by the Xiph.Org Foundation.

Theora is derived from the formerly 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 lacking some of the features present in some of these other codecs. It is comparable in open standards philosophy to the BBC's Dirac codec.

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

Theora is a variable-bitrate, DCT-based video compression scheme. Like most common video codecs, Theora also uses 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 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.


...
Wikipedia

...