[FFmpeg-devel] [PATCH v2 5/6] avutil/csp: add EOTF function definitions

[Niklas Haas]

On Sun, 01 Dec 2024 02:56:31 +0100 Michael Niedermayer <michael at niedermayer.cc> wrote:
> Hi
>
> On Sat, Nov 30, 2024 at 03:27:53PM +0100, Niklas Haas wrote:
> > On Sat, 30 Nov 2024 15:23:50 +0100 Niklas Haas <ffmpeg at haasn.xyz> wrote:
> > > From: Niklas Haas <git at haasn.dev>
> > >
> > > The existing av_csp_trc_func_from_id() mostly implements the OETF, except for
> > > PQ. As such, we are currently missing a precise definition of an ITU-R EOTF.
> > > Introduce the new functions av_csp_itu_eotf() and av_csp_itu_eotf_inv(), to fill
> > > this void. Note that this is not possible in all cases, e.g. AVCOL_TRC_LOG which
> > > has no corresponding EOTF definition in any ITU-R standard.
> > >
> > > Note that we cannot implement the proper HLG and SMPTE 428 OOTFs without access
> > > to all three color channels, because they are not independent per channel. As a
> > > result, we need to define a new type to encapsulate a color triplet. I have
> > > tentatively named this AVColor, in the hopes that it will become useful in other
> > > contexts as well. The choice of an array rather than explicitly named fields is
> > > to greatly simplify per-channel processing, matrix multiplications, and the
> > > like.
> >
> > Forgot to update the commit message. I decided to nuke AVColor in favor of
> > passing a double[3] directly. It only makes the code inside the test framework
> > marginally less pretty, and actually improves the usability of the API in other
> > contexts IMO.
> >
> > > ---
> > >  doc/APIchanges      |   4 +
> > >  libavutil/csp.c     | 205 ++++++++++++++++++++++++++++++++++++++++++++
> > >  libavutil/csp.h     |  33 +++++++
> > >  libavutil/version.h |   2 +-
> > >  4 files changed, 243 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/doc/APIchanges b/doc/APIchanges
> > > index db72121a61..12a2165837 100644
> > > --- a/doc/APIchanges
> > > +++ b/doc/APIchanges
> > > @@ -2,6 +2,10 @@ The last version increases of all libraries were on 2024-03-07
> > >
> > >  API changes, most recent first:
> > >
> > > +2024-11-25 - xxxxxxxxxx - lavu 59.49.100 - csp.h
> > > +  Add struct AVColor, type av_csp_eotf_function, av_csp_itu_eotf() and
>
> This still talks about AVColor

Already fixed locally, alongside the commit message change.

>
> thx
>
> [...]
>
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> Some people wanted to paint the bikeshed green, some blue and some pink.
> People argued and fought, when they finally agreed, only rust was left.
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