[theora] NHW Project - lower quality settings

Raphael Canut nhwcodec at gmail.com
Sat Mar 10 16:22:25 UTC 2018

Hi David!

Many thanks for your very encouraging and kind feedback!!! (Hope you don't
mind that I made your post public on the Theora channel).

I try to be the more sincere as I can in my posts.Some people suggested me
to make demo pages to explain how the codec works step by step, and I
realize that it would be good, because certainly it will show that the NHW
codec is not that complex and it will be more easy then to contribute for
people who want and have time.

For now, I focus on high compression settings, for me it's very complex,
but currently high compression settings are mandatory for a new image/video

Many thanks again for your feedback!

2018-03-10 16:57 GMT+01:00 David Willmore <davidwillmore at gmail.com>:

> I enjoy reading your posts and always find them educational.  I don't
> have anything to contribute other than my appreciation.  Thank you!
> On Fri, Mar 9, 2018 at 1:03 PM, Raphael Canut <nhwcodec at gmail.com> wrote:
> > Hello,
> >
> > I have re-tested -l4 high compression setting and it's clear that it
> lacks
> > of precision on degraded, rather blurred images. So I don't know if it
> is a
> > good idea to base the other lower quality settings (-l5,-l6,...) on -l4
> > setting.I have tested the NHW codec against x265, x264, Daala, WebP,
> Rududu,
> > DLI and it's clear that at high compression these very good codecs have
> more
> > precision.But they also tend to blur/decrease neatness-sharpness of image
> > where the NHW codec would enhance image neatness/sharpness.But that's
> right
> > that on degraded, blurred images where there is no neatness to enhance,
> the
> > results start to be not good and lack of precision.So for now, I
> recommend
> > to use -l4 setting on well-defined, good quality images.
> >
> > I have also "simply" increased the wavelet coeff threshold of the
> dead-zone
> > for -l5 setting (to save -5Ko), but the quality drop is too big for
> now.The
> > other codecs (above) don't have that drop in quality from -l4 to -l5
> > compression.So apparently, there needs to be more smartness to pass from
> -l4
> > to -l5 with the NHW codec.I'll try to work on this, but it's extremely
> > complex, for me...For example, Rududu doesn't have this problem, the
> codec
> > source code has been made available recently on GitHub, I have started to
> > study it and it is very powerful: advanced SPIHT tree-like coding,
> advanced
> > variance-based context modeling, advanced range coding, and other
> things...
> >
> > So to sum up, all the very good codecs quoted above have a very good
> > precision at high compression but they tend to decrease
> neatness/sharpness,
> > on the contrary of the NHW codec, but on degraded images where there is
> no
> > neatness/sharpness, the NHW codec then lacks of precision...
> >
> > Last but not least, for now the big advantage of the NHW codec I see, is
> > that it is very fast.The NHW codec is way faster than the codecs above,
> for
> > example it is still now H.264 technology that is used in mobile devices,
> and
> > the NHW codec compared to ultra-optimized x264 is x3 times faster to
> encode
> > and x1.2 times faster to decode, that is to say that with good
> optimization
> > (SIMD, multithreading) the NHW codec will be x12 times faster to encode
> and
> > x5 times faster to decode than x264...
> >
> > Again working on high compression is very complex, and any help would be
> > very welcome.And I know there are experts out there, more skilled than
> me,
> > that could have very good ideas for the NHW Project, if they could find
> the
> > time...
> >
> > Do not hesitate to contact me!
> >
> > Many thanks!
> > Cheers,
> > Raphael
> >
> >
> >
> > _______________________________________________
> > theora mailing list
> > theora at xiph.org
> > http://lists.xiph.org/mailman/listinfo/theora
> >
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