The Xiph.Org Foundation has taken the wraps off Daala, a "next-next-generation" video codec that has been under development for some time; this was until recently overshadowed by development work on the Opus audio codec at Xiph. However, the developers at the foundation think that the right time has come to open up development of the codec to a wider audience, even though they still classify the software as "pre-pre-alpha". According to Xiph, a prototype of the codec successfully encoded and decoded a video stream over the internet at the end of May.

The Xiph developers note that current next generation codecs such as VP9 and HEVC are "incremental refinements of a basic codec design that dates back 25 years to h.261", and say that Daala is trying a new approach that is at the same time more risky and more revolutionary than that of other codecs. Starting with a fresh approach sidesteps, according to the developers, "most of the patent thicket surrounding mainstream block-DCT-based codecs", and the problem that evolutionary improvements on those established codecs are increasingly producing diminishing returns.

Daala makes use of lapped transforms, a technique that is also used in audio codecs such as MP3, Vorbis and Opus and with which Xiph has extensive experience. The specific method used by the codec is described in the paper Lapped Regularity-Constraind Pre- and Post-Filtering for Block DCT Based Systems by Wei Dai and Trac D. Tran, and details on the implementation of the compression and filtering approach in Daala are available on a demonstration page on the Xiph web site.

Development on Daala, which is only a code-name, that could be dropped "once someone insists on something better", according to the project's wiki page at Xiph, is a collaboration between the Xiph.Org Foundation, Mozilla and outside contributors. Early in-development source code is available from a Git repository at Xiph and is licensed under a two-clause BSD licence. Documentation and IETF drafts for the codec can be found on Xiph's page for Daala.

(fab)