[PATCH] color-management: Add HDR-metadata support

[Harish Krupo]

Hi Ankit,

Nautiyal, Ankit K <ankit.k.nautiyal at intel.com> writes:

> From: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
>
> This patch adds HDR-metadata support in the color-management-protocol.
> It enables a client to:
> - know if an output is HDR capable.
> - set HDR-metadata values, received from an HDR content, for a surface.
>
> The HDR-metadata values : MAX_CLL, MAX_FALL, MAX_LUMINANCE,
> MIN LUMINANCE can be sent from the client to compositor, which can
> inturn send these to kernel. Kernel can finally send these values in

typo: in turn :)

> AVI-INFOFRAMES to the HDR display to provide an idea of the brightness
> of the content. The display can use this information to adapt itself
> for a better viewing experience.

You can also add that this information could be used for tone mapping
when composing along with other buffers.

>
> Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
> ---
>  .../color-management-unstable-v1.xml               | 48 +++++++++++++++++++++-
>  1 file changed, 46 insertions(+), 2 deletions(-)
>
> diff --git a/unstable/color-management/color-management-unstable-v1.xml b/unstable/color-management/color-management-unstable-v1.xml
> index 7b4d08e..58a41a1 100644
> --- a/unstable/color-management/color-management-unstable-v1.xml
> +++ b/unstable/color-management/color-management-unstable-v1.xml
> @@ -119,7 +119,15 @@
>        <arg name="id" type="new_id" interface="zwp_color_space_v1"/>
>      </request>
>  
> -    <!-- TODO: HDR capabilities event -->
> +    <event name="hdr_capability">
> +      <description summary="HDR Capability">
> +	This event is sent after creating a zwp_color_management_output
> +	(see zwp_color_manager.get_color_management_output) and tells about the
> +	HDR capability of an output. A value of '1' indicates that the output
> +	is HDR capable, and '0' indicates a non-HDR output.

Can the client span across outputs? If so what will the client receive?
1 or 0?

> +      </description>
> +      <arg name="hdr_support" type="uint"/>
> +    </event>
>  
>      <request name="destroy" type="destructor">
>        <description summary="destroy the color management output">
> @@ -171,7 +179,43 @@
>        <arg name="render_intent" type="uint" enum="render_intent"/>
>      </request>
>  
> -    <!-- TODO: HDR metadata request -->
> +    <request name="set_hdr_metadata">
> +      <description summary="set the hdr metadata for the surface">
> +	Set the HDR-metadata for the underlying surface. The HDR-metadata is
> +	double buffered, and will be applied at the time wl_surface.commit of
> +	the corresponding wl_surface is called.
> +	The HDR-metadata constitutes of MAX-CLL, MAX-FALL, Max Luminance and
> +	Min Luminance as defined by SMPTE ST.2086. The clients get these values
> +	for an HDR video via ffmpeg 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. All except for Minimum Luminace, can be represented by integer,
> +	as they take values of the order of hundreds of nits.
> +	For Minimum Luminance, fixed type is used so that it can take smaller
> +	decimal values, which can be converted to and from double.
> +
> +	For setting color-primaries as part of HDR-metadata, the client should
> +	manufacture the icc profile and then use the zwp_color_manager interface
> +	to get the color-space, (see zwp_color_manager.create_color_space).
> +	The request set_color_space can then be used to set the color-space.
> +
> +	A client may request for setting the HDR-metadata for a surface, even if
> +	there is no HDR-capable output, compositor should handle such cases.
> +

"Should" sounds a bit assertive. Maybe drop the sentence?

> +	The HDR-metadata should be initialized with '-1' for a surface,
> +	signifying that the values are invalid. So, If a client does not set
> +	hdr-metadata values for a surface, i.e. does not request
> +	set_hdr_metadata default value of '-1' will be there, telling the
> +	compositor that there is no HDR-metadata for that surface.
> +      </description>
> +      <arg name="max_cll" type="uint"/>
> +      <arg name="max_fall" type="uint"/>
> +      <arg name="max_luminance" type="uint"/>

max_cll and max_fall are uints but max_luminance is of fixed type.
Also, what happens when the clients wants to reset the hdr metadata?
Would it set -1 to all the values to notify of this change?
I think all of them should be of fixed types to be able to send -1.

> +      <arg name="min_luminance" type="fixed"/>
> +    </request>
>  
>      <event name="preferred_color_space">
>        <description summary="preferred color space">

Thank you
Regards
Harish Krupo