Dirac

Dirac is a video codec that provides general-purpose video compression and decompression tools comparable with state-of-the-art systems.

Dirac video codec is available for distribution under the MPL version 1.1 software license.

Dirac is an open source video codec. It uses a traditional hybrid video codec architecture, but with the wavelet transform instead of the usual block transforms. Motion compensation uses overlapped blocks to reduce block artefacts that would upset the transform coding stage.

Dirac can code just about any size of video, from streaming up to HD and beyond, although certain presets are defined for different applications and standards. These cover the parameters that need to be set for the encoder to work, such as block sizes and temporal prediction structures, which must otherwise be set by hand.

Dirac is intended to develop into real coding and decoding software, capable of plugging into video processing applications and media players that need compression.

It is intended to develop into a simple set of reliable but effective coding tools that work over a wide variety of content and formats, using well-understood compression techniques, in a clear and accessible software structure. It is not intended as a demonstration or reference coder.

What is new in this release:

• Improved compression performance for small picture sizes.
• Improved compression performance at low bit-rates.
• Included macros to check the API version.
• Improved motion estimation.
• New 422 420 conversion utilities for interlaced video.
• New functionality added to encoder API. The programmer's guide has been modified accordingly.
• Fixed bugs in handling DC subband.
• DirectShow filter released to be able to play back Dirac raw bytestreams or Dirac muxed in AVI in Windows Media Player and MPlayer Classic.
• Released the source and win32 binary of ffmpeg2dirac, a utility that can transcode any multimedia format that can be decoded by FFmpeg into Dirac video and Vorbis audio (if audio exists) muxed in Ogg.
• Note that new patches for MPlayer and FFmpeg will no longer be released because Dirac support via Dirac and Schroedinger libraries is available in FFmpeg.

What is new in version 1.0.0:

• Encoder classes have been refactored to make coding processes more clear.
• Minor bugs have been fixed.
• Compression efficiency is improved.
• A DirectShow filter to play back Dirac files in Windows Media Player has been released.
• Support for Dirac encoding, decoding, and muxing via Dirac libraries and Schroedinger libraries is now available in FFmpeg and MPlayer.