[theora] NHW Project and wavelet codecs

[Raphael Canut]

Hello,

In my last post, I seemed to say that there were no directional wavelet
transforms that would give improvement to the NHW codec, but are
directional wavelets an active research field today? I have also seen some
recent patents on advanced and improved SPIHT, and I am a little surprised
that there is no "up-to-date" state-of-the-art wavelet codec.Rududu in
April 2008 was the last advance in SPIHT research (but does not select
directional wavelets) with very good results.If I remember the author post
there is furthermore an interesting fast context modeling based on the 2x2
variance of wavelet coefficients in order to reduce the context cost per
coeff, associated with an also interesting range coder (division-free) that
can be skipped to code raw bits or with huffman, rice-golomb... Wavelet
transforms, SPIHT, context modeling have improved since 2008, so why no new
updated wavelet codec, as it was the case of HEVC for H.264 (Rududu is
similar in performance with x264 intra, PSNR- and SSIM- wise)? -Do wavelets
have so much bad reputation?-

Ok that's right the NHW codec is a wavelet codec, but it's a totally new
approach, with an emphasis on speed (extremely fast with a good visual
quality, neatness/sharpness preserving) mainly designed to fit with
portable devices.

Just last words, I am still searching to work full-time on the NHW
Project.I have taken some contacts, and am waiting for some answers, but if
you, your company are interested in the NHW Project, please do not hesitate
to contact me.

Many thanks!
Cheers,
Raphael
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