[theora] NHW codec

[Raphael Canut]

Hello,

I would like to discuss a little about the NHW codec and its state after
nearly 5 years on the Xiph forums.

I also know that if I would like to discuss I'd better go to the great
Doom9 and Encode.ru forums but for now I find that my codec is too
experimental for these professional forums:

- the codec is only for fixed 512x512 size, just a test tool.
- there is only mid compression
- for high compression, all the quantization scheme must be redesigned
- all the compression schemes (wavelet DC image, wavelet coeffs, residual
coding if I keep it...) must be improved
- change the chroma subsampling
- when all that is done, adapt the codec to any size of image.

So I prefer stay on the Xiph Theora channel for now and post my updates.

Also some people could say that after 5 years on the forum without raising
interest, I should think about abandoning now in the era of AOM AV1 and
HEVC.But first it is very hard for your codec to not catch attention and
don't have answers, but what is even harder is that I find the NHW codec
still competitive (even in its current state).

For example, I have made a visual comparison for mid compression (-l2 to
-h2 setting) on 50 images of the NHW codec with BPG (HEVC intra), WebP, and
Rududu Image Compression (Rududu is a powerful wavelet image codec,
released in April 2008, that is based on SPIHT-like, zerotree coding, -it
totally went under-the-radar...-).

Results: The codec that has the more precision is BPG, the codec that has
the more neatness is NHW.Don't know what is the best criterion between
neatness and precision, but globally on 25 images out of 50 I visually
prefer the results of NHW for its neatness, on 20 other images I visually
prefer the results of BPG for its precision.

Does someone share this opinion?

Also, the NHW codec is a lot faster than these codecs and is royalty-free.

Again feel free to answer me on this forum or on my email if you have any
remark, comment,... would be great.

Many thanks.
Cheers,
Raphael
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