[PATCH] unstable: add HDR Mastering Meta-data Protocol

[Kps, Harish Krupo]

> From: Pekka Paalanen [mailto:ppaalanen at gmail.com]
> Sent: Friday, March 1, 2019 7:49 PM
> To: Nautiyal, Ankit K <ankit.k.nautiyal at intel.com>
> Cc: wayland-devel at lists.freedesktop.org; sebastian at sebastianwick.net;
> Sharma, Shashank <shashank.sharma at intel.com>; e.burema at gmail.com;
> niels_ole at salscheider-online.de; Kps, Harish Krupo
> <harish.krupo.kps at intel.com>
> Subject: Re: [PATCH] unstable: add HDR Mastering Meta-data Protocol
> 
> On Fri, 1 Mar 2019 14:40:16 +0530
> "Nautiyal, Ankit K" <ankit.k.nautiyal at intel.com> wrote:
> 
> > Hi Pekka,
> >
> > Thanks for the comments and suggestions.
> >
> > Please my responses inline:
> >
> > On 2/28/2019 7:51 PM, Pekka Paalanen wrote:
> > > On Wed, 27 Feb 2019 10:27:16 +0530
> > > "Nautiyal, Ankit K"<ankit.k.nautiyal at intel.com>  wrote:
> > >
> > >> From: Ankit Nautiyal<ankit.k.nautiyal at intel.com>
> > >>
> > >> This protcol enables a client to send the hdr meta-data:
> > >> MAX-CLL, MAX-FALL, Max Luminance and Min Luminance as defined by
> > >> SMPTE ST.2086.
> > >> The clients get these values for an HDR video, encoded for a video
> > >> stream/file. MAX-CLL (Maximum Content Light Level) tells the
> > >> brightest pixel in the entire stream/file in nits.
> > >> MAX-FALL (Maximum Frame Average Light Level) tells the highest
> > >> frame average brightness in nits for a single frame. Max and Min
> > >> Luminance tells the max/min Luminance for the mastering display.
> > >> These values give an idea of the brightness of the video which can
> > >> be used by displays, so that they can adjust themselves for a
> > >> better viewing experience.
> > >>
> > >> The protocol depends on the Color Management Protocol which is
> > >> still under review. There are couple of propsed protocols by Neils
> > >> Ole [1], and Sebastian Wick [2], which allow a client to select a
> > >> color-space for a surface, via ICC color profile files.
> > >> The client is expected to set the color space using the icc files
> > >> and the color-management protocol.
> > >>
> > >> [1]https://patchwork.freedesktop.org/patch/134570/
> > >> [2]https://patchwork.freedesktop.org/patch/286062/
> > >>
> > >> Co-authored-by: Harish Krupo<harish.krupo.kps at intel.com>
> > >> Signed-off-by: Ankit Nautiyal<ankit.k.nautiyal at intel.com>
> 
> > >> diff --git
> > >> a/unstable/hdr-mastering-metadata/hdr-mastering-metadata-unstable-v
> > >> 1.xml
> > >> b/unstable/hdr-mastering-metadata/hdr-mastering-metadata-unstable-v
> > >> 1.xml
> > >> new file mode 100644
> > >> index 0000000..aeddf39
> > >> --- /dev/null
> > >> +++ b/unstable/hdr-mastering-metadata/hdr-mastering-metadata-unstab
> > >> +++ le-v1.xml
> > > Could it be named hdr-mastering rather than hdr-mastering-metadata?
> > > Shorter C function names wouldn't hurt.
> > Yes I guess, thanks for the suggestion, or perhaps "hdr-metadata" ?
> 
> Hi Ankit,
> 
> to me, the word "metadata" is the redundant one. "HDR" is significant,
> "mastering" is probably significant as well, but since we are talking about
> Wayland, half of the protocol is essentially metadata.
> 
> But "hdr-metadata" is not bad either.
> 
> Then we have hdr_surface.set_hdr_mastering_metadata. That could be simply
> hdr_surface.set_metadata... or hdr_surface.set_luminance since all the
> arguments are about luminance somehow.
> 
> Does mastering metadata include more than just luminance parameters?
> The primaries and white point maybe?
> 

Yes, it does. It contains the primaries and white point along with luminance 
of the display used for mastering the content.