[FFmpeg-devel] [PATCH 5/5] libavcodec/ffv1: Support storing LSB raw

[Michael Niedermayer]

On Tue, Oct 22, 2024 at 04:22:06PM +0200, Lynne via ffmpeg-devel wrote:
> On 16/10/2024 15:26, Michael Niedermayer wrote:
> > This makes a 16bit RGB raw sample 25% faster at a 2% loss of compression with rawlsb=4
> > 
> > Please test and comment
> > 
> > This stores the LSB through non binary range coding, this is simpler than using a
> > separate coder
> > For cases where range coding is not wanted its probably best to use golomb rice
> > for everything.
> > 
> > We also pass the LSB through the decorrelation and context stages (which is basically free)
> > this leads to slightly better compression than separating them earlier.
> > 
> > Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
[...]
>
> TBH I'm still not a fan of this and I don't think it should be part of
> version 4. It seems like it'll be a very niche coding feature that's better
> served by Golomb-Rice coding, which is many times faster as you can
> *parallelize* it.
> It could potentially help improve compression of noisy images as the noise
> wouldn't affect EC state, but without a search mechanism, leaving it in the
> hands of users is bound to lead to a misuse.

32bit float support will likely be in v4, and i imagine from 32bit some will
be random. So some kind of raw lsb support seems important, at least for some
content.

In that sense, if someone has 32bit float material, i would be interrested
in having a copy for developing/testing future 32bit float support

thx

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Those who would give up essential Liberty, to purchase a little
temporary Safety, deserve neither Liberty nor Safety -- Benjamin Franklin
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