Bug Kodi Setting RGB Limited/Full not respected for videos when using DRM Prime? Bug?
Hi everyone,

I think there is a bug making Kodi ignore the Limited/Full range setting when DRM Prime decoder is enabled, making Kodi always output in Full range.

But from the beginning:
I recently installed LibreELEC (11.0.3 (RPi4.arm)) to my RPi4 and I tried to set up video levels correctly. I read this page:

What I have learned is that the best setting is:
Kodi: Limited
GPU: Full
TV: Limited

The GPU was set to "auto" by default, and I was unsure if this actually works with my >15 years old LCD, so I set GPU to "Full" via modetest in autostart.sh. (EDIT: Before, I wrote I set GPU to "Limited" which was wrong!)

Anyway, the problem:

Regardless if I configure Kodi to "Limited" or "Full", when playing video, it always looks the same. The actual Kodi menus and when viewing images change as expected.
So I think the video level settings in Kodi are ignored when playing video files using RPi4.

I could get it to work by disabling DRM Prime Decoding in the Kodi settings. When I do that, then the video looks (and changes) as expected in regard to the video level setting.
When enabling DRM Prime, then I get the same looks as when putting Kodi to "Full".
So, I think when DRM Prime is enabled, then Kodi always outputs video as "Full" even when Kodi is configured to "Limited". I hope, I could make myself clear Smile

When doing the same on my Intel NUC, then the Kodi Full/Limited setting has an effect when showing videos. So I think this bug (if it is a bug) is RPi specific.
Not a bug. The limited/full setting only affects GL rendering.

DRM uses a different path and this shouldn't be required.
The decoded video plane includes a colourspace attribute which describes full/limited encoding.
And this gets through to the (kernel) DRM display driver which will handle signalling full/limited range
over hdmi. And if not supported, it will convert to the range supported by display.
Hm, ok, so what you say is that when watching videos with DRM, then the Kodi limited/full setting is irrelevant and stuff should automatically be "correct"?

So either:
* If the TV supports it: Kernel will tell the TV to use limited or full and the TV will ignore what is configured in its own settings
* Otherwise, the kernel will detect what is configured on the TV (so, if TV expects limited or full) and converts the video accordingly

But the problem still is as described: When having DRM enabled on Kodi, then I am quite sure the video reference levels are reaching the TV as "full" (even when TV is configured to "limited"). Setting the video level setting on the TV clearly makes a difference (so not overridden by HDMI) and it is only correct when setting it to "Full" on the TV.

And another sign of the problem: The video levels between watching video and Kodi UI or watching images are different. They should be same right? So, either I manually misconfigured the GL-path or the DRM-path did something wrong with the auto-detection, right? As said, for the GL-path I set Kodi to "limited", GPU to "full" and TV to "limited", so I am quite sure this is correct?

I was wrong when I said the problem only happens on my Pi but not on my NUC: It seems DRM on my NUC defaulted to "off". When I enable it manually then I am having the exact same behavior that the video seems to be always sent as "full" to the TV (while the TV is configured to "limited").
Related question: Should I enable DRM on the NUC or should it let it off?

My two setups:
2. Rpi4 + LE40M86BD (stone age)
Is there a way to manually force the DRM path to output as "limited"? I could then at least confirm if the behavior I am observing is correct or not. When I could force it to "limited" then the picture should not change on my TVs because DRM is currently supposed to output "limited" anyway.
It shouldn't be necessary unless the display is not respecting the full/limited signalling in the AV Infoframe.
But see here for how to manually set it.

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