[wrxtasy]

@wrxtasy 

Thank you for the very detailed reply, I am slowly understanding more and more.

So confirmed by HDMI analysis

1.  Odroid N2 (s922) running CoreELEC outputs MaxFALL/MaxCLL metadata
2.  Vero 4k+ (s905d) running the OSMC "new stack" (whatever that is) outputs MaxFALL/MaxCLL metadata

No the Vero 4K's need a new Kernel first. And then testing has to happen, and likely further bug busting.

Kernel

1.  The 3.14 kernel does not support outputting metadata like MaxFALL/MaxCLL

Correct for AML devices running LE, OSMC or CE.

2.  The 4.9 kernel is a propriety kernel made by AMLOGIC just for their s905 and s922 devices. And they did not make it for the s912.

If you look in this AML Mbox table (click), devices that can run Android 8.0 and above are able to run the v4.9 AML Linux Kernel.
The S905D, is a S905X with DVB extras added.
Any other S9xx chipset would need a Kernel backport or wait for Mainline Linux to catchup up for full HDR metadata support.

3.  The 3.14 and 4.19/4.1x kernels are standard linux kernels ?

Yes in mainstream Linux land.
Vendors like AMLogic can add their own patches to any Kernel to support chipset specific functionality if they want, like HDR Metadata output.

4.  The 4.19/4.1x kernel "does" support outputting metadata like MaxFALL/MaxCLL

Such support is being added slowly to Linux Mainline, see HERE (click) - You will also need driver and Software support, like Linux HDR Kodi v19 M.

5.  The 4.9 kernel used by CoreELEC on the Odroid N2 has been modified by either CoreELEC or Hard Kernel to better support colour space autoswitching and other things.

AML did or paid for most of the custom v4.9 Kernel work, mainly for Android TV Oreo / Pie devices. HK and CE do bug busting and optimising for S922X AML Linux Kodi.

6.  The s912 "may" or "may not" be able to output HDR metadata like MaxFALL/MaxCLL when or if someone gets the 4.19/4.1x kernel working on it next year.

If all the starts align - Maybe.

Mainline unified Linux Kernels, drivers and Linux HDR Kodi v19 M support is where it will all hopefully come together for all ARM based - HDR - Rockchip, Allwinner, AMLogic & more , plus HDR capable Intel / AMD Linux devices. Uniting them all under a single HDR Linux Kodi v19 M release umbrella.

A lot of water has to go under the bridge before that happens yet.

In the meantime there will continue to be custom Linux Kodi Leia HDR releases - or you use auto switching - Android TV or FireTV 4K - HDR capable Kodi devices from this list: https://forum.kodi.tv/showthread.php?pid...pid2823690