Dirac (video Compression Format) - Software Implementations

Software Implementations

Two software implementations of the specification currently exist. The first is the BBC's reference implementation, formerly just called Dirac but renamed dirac-research to avoid confusion. It is written in C++ and released under the Mozilla Public License, GNU GPL 2 and GNU LGPL free software licenses. Version 1.0.0 of this implementation was released on 17 September 2008.

A second implementation called Schrödinger was funded by the BBC and aims to provide high-performance, portable version of the codec whilst remaining 100% bitstream compatible. Schrödinger is written in ANSI C and released under the same licenses as dirac-research, as well as the highly-permissive MIT License. The Schrödinger project also provides GStreamer plugins to enable the library to be used with that framework. On 22 February 2008, Schrödinger 1.0.0 was released. This release was able to decode HD720/25p in real-time on a Core Duo laptop.

As of the release of Schrödinger-1.0.9, "Schrödinger outperforms dirac-research in most encoding situations, both in terms of encoding speed and visual quality". With that release, most of the encoding tools in dirac-research have been ported over to Schrödinger, giving Schrödinger the same as or better compression efficiency than dirac-research.

An encoder quality testing system has been put in place at BBC to check how well new encoding tools work and to make sure bugs that affect quality are quickly fixed.