Subject: [video-codec] NHW: a wavelet image codec

From: Raphael Canut <[email-masked]>
Date: Wed, 12 Aug 2015 19:41:20 +0200

Hello,

New to this list, I am submitting the NHW codec to your working group.NHW
is an experimental wavelet codec, that I presented on the Xiph Theora
channel, it uses (normally) new non-patented techniques (it is normally
royalty-free).Its main advantages are speed and neatness of image.

Here are the links:
demo page: http://nhwcodec.blogspot.com/
github repo: https://github.com/rcanut/nhwcodec

If some parts could be selected for test in the NETVC project, would be
just great.The main interesting parts are: a new fast wavelet transform, a
multistage residual coding, and 3 new entropy coding schemes, which one is
very efficient and very fast for quantized coefficients in video/image
compression.

Do not hesitate to let me know if I am submitting the right way.

Many thanks.
Cheers,
Raphael

---

From: "Timothy B. Terriberry" <[email-masked]>
Date: Wed, 12 Aug 2015 11:23:05 -0700

Raphael Canut wrote:
> just great.The main interesting parts are: a new fast wavelet transform,
> a multistage residual coding, and 3 new entropy coding schemes, which
> one is very efficient and very fast for quantized coefficients in
> video/image compression.

Thanks for the contribution. There are several ways to go from here.

One thing that would be interesting to know would be the performance 
compared to Daala and Thor. I would suggest working with Thomas Daede 
<[email-masked]> to make that happen.

Another thing would be to try to integrate pieces of the other 
submissions into your codec or pieces of your codec into the other 
submissions, to see if you can demonstrate improvements. Some examples 
of how we have been doing this for Daala and Thor are here:

https://review.xiph.org/874/
https://github.com/cisco/thor/pull/8

One potentially interesting area to experiment with might be be the 
prototype screencasting experiments in Daala presented at IETF 93: 
https://tools.ietf.org/html/draft-valin-netvc-l1tw-01

Those are using wavelets, so they might benefit from some of what you 
are doing.

---

From: Raphael Canut <[email-masked]>
Date: Wed, 12 Aug 2015 21:15:47 +0200

Hi Timothy,

Many thanks for your answer.

2015-08-12 20:23 GMT+02:00 Timothy B. Terriberry <[email-masked]>:

> compared to Daala and Thor. I would suggest working with Thomas Daede <
> [email-masked]> to make that happen.
>
> That's a good idea, but keep in mind that the NHW codec is optimized for
neatness (and sharpness), so results for PSNR and SSIM are not good (there
are more "errors").For now, the best way I have found to evaluate the NHW
codec is to visually evaluate it.... It is also now optimized for
mid/normal compression, there are no high compression settings... It's
still experimental!

> Another thing would be to try to integrate pieces of the other submissions
> into your codec or pieces of your codec into the other submissions, to see
> if you can demonstrate improvements. Some examples of how we have been
> doing this for Daala and Thor are here:
>
> We can try first with the entropy coding for the wavelet coefficients.I
would be really interested in trying Daala's arithmetic coder.

> Those are using wavelets, so they might benefit from some of what you are
> doing.
>

I have read the draft, in my codec I am using 5/3 (and 9/7) wavelets.I have
read that you are using tree coding like SPIHT and EZW.I would be
interested in understanding more and trying this technique.

Many thanks.
Cheers,
Raphael

---

From: Thomas Daede <[email-masked]>
Date: Wed, 12 Aug 2015 12:24:21 -0700

On 08/12/2015 12:15 PM, Raphael Canut wrote:
> 2015-08-12 20:23 GMT+02:00 Timothy B. Terriberry <[email-masked]
> <mailto:[email-masked]>>:
> 
> 
>     compared to Daala and Thor. I would suggest working with Thomas
>     Daede <[email-masked] <mailto:[email-masked]>> to make that happen.
> 
> neatness (and sharpness), so results for PSNR and SSIM are not good
> (there are more "errors").For now, the best way I have found to evaluate
> the NHW codec is to visually evaluate it.... It is also now optimized
> for mid/normal compression, there are no high compression settings...
> It's still experimental!

We do have a couple of other metrics that value detail retention more,
such as PSNR-HVS and FASTSSIM in our code tree.

To be able to hook your codec up to arewecompressedyet, it needs to
support YUV 4:2:0 input and output in the y4m format.

---

From: Raphael Canut <[email-masked]>
Date: Wed, 12 Aug 2015 21:42:13 +0200

Hi Thomas,

The NHW codec is at very early experimental stage (it's an image codec
furthermore, not a video codec), and image input size is fixed 512x512 size
for now.

Also, the NHW codec is not very good at detail retention, but it gives more
neatness, sharpness to image contours, edges.

Cheers,
Raphael

2015-08-12 21:24 GMT+02:00 Thomas Daede <[email-masked]>:

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