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

[Pekka Paalanen]

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-v1.xml b/unstable/hdr-mastering-metadata/hdr-mastering-metadata-unstable-v1.xml
> >> new file mode 100644
> >> index 0000000..aeddf39
> >> --- /dev/null
> >> +++ b/unstable/hdr-mastering-metadata/hdr-mastering-metadata-unstable-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?


Thanks,
pq
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