Daala was not in the limelight because its development was overshadowed by the work on Opus audio codec which was going on at the Foundation. The foundation revealed that at the end of May, a prototype of the codec was successfully used to encode and decode a video stream over the Internet. For this reason developers at Xiph.org believe that now is the right time to unravel the codec and put it forward to a wider audience. The codec has been released as a classification of “pre-pre-alpha”. The codec is being worked upon by developers at Xiph, Mozilla and other outside contributors.
According to the developers of the Daala codec even though VP9 and HEVC are next-generation codecs, they basically carry “incremental refinements” brought about in the original h.261 codec which is 25 years old. The new codec takes completely new and fresh approach that sidesteps “most of the patent thicket surrounding mainstream block-DCT-based codecs.”
The new codec uses lapped transforms – a technique which is used in MP3, Opus and Vorbis audio codecs and the specific method used by Daala is described by Wei Dai and Trac D in their paper titled Lapped Regularity-Constraind Pre- and Post-Filtering for Block DCT Based Systems [PDF]. If you are keen on details of the practical implementation of the compression and filtering approach used in the new codec, you can head on to demonstration page on Xiph.org.