Dirac (video format)

from Wikipedia, the free encyclopedia
File extension : .avi, .ogv, .ts, .mkv, andere
Developed by: BBC
Type: Video format , lossy video data compression
Contained in: Ogg , MPEG-TS , AVI , Matroska , others

Basic data

developer BBC
Current  version 1.0.11
(January 23, 2012)
programming language C.
category free video codec
License MPL

Dirac is a format for lossy compressed video data published by the BBC in May 2004 , which is intended to be a free alternative to formats such as Microsoft's Windows Media Video or those of the Moving Picture Experts Group . Particular care is taken to ensure that no technologies patented by third parties are used.

Dirac was completed on January 21, 2008. The reference implementation is written in the C ++ programming language. In addition, a project was started under the name Schrödinger with the aim of an optimized and portable implementation of the Dirac specifications.

This first implementation was completed on March 11, 2008 and is version 1.0.

The open source codec published under the Mozilla Public License 1.1 (MPL) allows relicensing of the code under version 2.0 of the GNU General Public License (GPL) and version 2.1 of the GNU Lesser General Public License (LGPL).

In order to achieve the highest possible compression rates without the formation of artifacts , Dirac uses - in contrast to competing formats such as H.264 - a discrete wavelet transformation as well as techniques such as motion compensation and arithmetic coding , which, in addition to low memory consumption at high resolutions, also use the format for Internet streaming - Make applications seem appropriate. The resolution ranges from QCIF (176 × 144 pixels) to HDTV (1920 × 1080 pixels) and higher.

When it was published, there was talk of halving the data rate compared to the MPEG-2 standard with a resolution of 1920 × 1080 pixels . This positions Dirac as a competitor to H.264 and VC-1 .

In addition to the free software community, various universities are also developing the codec further.

A subset without inter-coding has been standardized by the Society of Motion Picture and Television Engineers as VC-2 (standards SMPTE 2042-1-2009 and SMPTE 2042-2-2009).

See also

Web links

Individual evidence

  1. Freie Universität Berlin - Institute for Computer Science: Elaboration: The Dirac wavelet codec and automated quality comparison using the GStreamer framework (PDF; 3.6 MB)
  2. SMPTE 2042-1: 2012 . Retrieved September 9, 2015.