I’m in the same boat as you, completely forgot about all of this until randomly coming to check here today. I’ve been using an odroid n2+ since they came out and have since moved from worrying about hdr on intel/Linux to what devices I need to playback (mkv) dolby vision now 
If I have time I might dig out my nuc and give it a go though.
Looks like Windows v19 nightlies now include patches to make it work without having to use external players. Still would prefer to have a *nix based solution.
Yeah it works well, I had been using the builds before it got merged into the nightlies but eventually I gave up with windows update breaking dual boot etc
I’ll go back to my NUC when/if HDR is sorted but for now I’m happy using the N2+.
Yeah, it forces the output to 8-bit.
Did you ever try Windows on your NUC? I wonder if Windows driver also force 8-bit.
I have used hdr quite a bit on Windows.
Funnily enough with my old Samsung tv I was getting constant white flickering - so a while ago I contacted Intel support about it, and after a lot of back and forth they eventually came back and said that the NUC did not support 8 bit, only 10 bit and the reason the flickering was occurring is to due to the tv panel being 8 bit. Can confirm on my new 10bit tv it doesn’t occur so not sure whether it was true or not.
At any rate - that’s why I was curious about this patch forcing 8bit when the support people told me it could only output 10 bit - maybe that’s a Windows ‘hdr mode’ thing?
Edit: this is the reply I got, maybe at the time I just took that to mean it only outputted 10bit...
Of course, I’m sure the devs know a lot more than the support 
In the Technical White Paper for HDR on Intel Graphics (HDR_Intel_Graphics_TechWhitePaper.pdf) it is specified that Intel Graphics only supports HDR10 - would you be able to confirm with the TV manufacturer that their specific model supports HDR10?
Thanks smp.
Curious - does that patch read to you as if the NUC will output only 8bit?
Same result as previously for me unfortunately. Just black screen.
I used the AVR key I have lying around to try and get a little more info behind the scenes, screenshot attached. On the left is Odroid N2+ and the right is the NUC8i5 running this build. Same file.
I’ve been keeping an eye on the intel patches, seems like it’s gone quiet for anything HDR related for about two months now?
Hopefully that’s just holidays etc and not a bad sign 
those who testing and getting blank screen are you on samsung tvs?
LG Oled CX for me
Some new patches for LSPCON HDR just showed up.
[v5,08/11] drm/i915/lspcon: Create separate infoframe_enabled helper - Patchwork
[v5,09/11] drm/i915/lspcon: Do not send infoframes to non-HDMI sinks - Patchwork
[v5,10/11] drm/i915/lspcon: Do not send DRM infoframes to non-HDMI sinks - Patchwork
If you feel like trying them here's an image.
Thanks for posting this!
Pretty much same result as last time, no video but have sound and tv switching to hdr.
This time I also got no UI/playback menu as well so something has changed at least
Happy to keep testing and waiting 
No I just meant the patch to fix the audio issue was included in 9.2.2 hotfix release.
Those with no video on HDR files, you are not using Gemini Lake correct?
Correct, not using Gemini lake.
The build we just tried had patches for LPSCON controller which Gemini lake doesn’t have either so shouldn’t effect Gemini lake.
Does it play non-HDR video (with drmprime hw decoder enabled)?
Good shout, sorry didn’t even think of that as all my HDR stuff is on a separate disk.
Yes, non hdr videos play fine with drmprime.
I’d still like to wait for someone else to test just to rule out my setup 
- or me doing something silly 
Downloaded but too tired tonight to test it out. Prolly won't have time to try it out till this weekend. PlatypusW any luck?
Thanks for the image smp.
I had the same as before - no video. That said, this time the tv did switch into HDR mode so that is (big) progress on what happened last time for me.
Not sure if the video is audio related, I tried both plugged into avr with passthrough and plugged straight into tv with no passthrough.
Let’s see how others get on.
I was wondering if anyone was able to reliably get HD Audio passthrough using the thunderbolt 3 port on a NUC (8,9,10) running libreelec?
Thanks for the reply, am I missing something obvious there? My NUC is definitely 8th gen and is listed as having:
Thunderbolt™ 3 USB-C port providing DisplayPort 1.2 or USB 3.1 gen 2
I would understand if it shouldn’t work and in fact never worked. That would be great actually.
But what actually happens is that HD Audio works, but only about 5% of the time. The only thing I have to do is stop and start the video again and it might just decide to work.
It’s enough that it annoyingly doesn’t just flat out ‘not work’ but doesn’t work enough that it’s actually usable.
At this point, I’d love to just know why if nothing else. As I said, am I missing something obvious?
New Linux patches just showed up which add HDR support for Parade Technologies LSPCON controller as well as MCA LSPCON controller. If anyone wanna try them I can build an image.
Definitely up for trying it on my NUC8i5 if you don’t mind building an image!
Is anybody able to explain why this seems to be so flaky?
I tried starting and stopping a dts-hd file 20 times to see how often I got passthrough sound, results:
Club adaptor: 0%
Anker cable: 5%
Apple adaptor: 40%
Why is it like this? Drivers? EDID?
I somehow don’t think getting a specific adaptor is going to help is it?
Is this an intel problem? It works 100% of the time with all adaptors in windows.
Is it even worth me trying a different build, e.g a Milhouse build?
Does anyone have any recommendations for a Thunderbolt 3 (USB C) -> HDMI cable/adaptor that supports HD audio passthrough in Linux/Libreelec?
For a while I couldn't understand why I was only able to get HD audio out of the NUC's thunderbolt 3 port within Windows until I stumbled upon this thread: Intel NUC8i3BEH Audio Issue
Unfortunately the product link in that thread no longer work, does anyone have any others they know that work?
I have tried Anker USB C -> HDMI (Only works in windows), and recently tried the Club 3D adapator which annoyingly also doesn't work (I don't know if I should be reaching out to them to see if theres a firmware update?).
Surprising, I randomly tried my iPad's USB C to HDMI adapator and that kind of worked, but the audio had slight interference.
Potentially this might work?
Limited Display Modes/No Sound
Amazon.com: Cable Matters USB C to HDMI Adapter (USB-C to HDMI Adapter) Supporting 4K 60Hz in Black - Thunderbolt 3 Port Compatible for MacBook Pro, Dell XPS 13, 15 and More: Computers & Accessories
No go for me 
Made sure prime hw decode was on (can see it’s using ff-hevc-drm_prime(HW)).
Anyway, all I get is blank screen. Can see it’s playing though. No hdr switch not that it would help with no video
Something is going funny with audio too as it isn’t picking up any device and is greyed out on Bluetooth, that may or may not be related.
For the record this is clean install on an empty m2 so happy to try again in the future if needs be.
Tv is Samsung UE40MU6400
I can get you logs if you think it would help, but I’m by no means expecting you to support anything, just trying to help out test, which I feel may be a little too early to do yet.
I would be up for testing too, but I also have an 8th gen NUC (i5), and the patches seem to specify just the 9th gen? Is it too early for 8th gen at the moment?
HDR in some degree obviously works with it as I have a windows partition purely for watching HDR content.
I followed this for my nuc. It was to dual boot windows but hopefully helps with Ubuntu too?
Any chance I can pick your brain PlatypusW? I have an 8th gen NUC and its not working out for me I feel. When I enable HDR in windows it looks horrible, so washed out and gray. Your not having this issue?
It was a while ago that I sorted my windows setup now, pretty much got the NUC at launch. I didn’t note much down as I didn’t plan on having a windows OS for very long as I was hoping Linux would be sorted out by now but clearly not (though it sounds like it’s getting closer).
I’ll admit I had a few hiccups with setup - but at the time I felt that was down to the tv model I was using - there seemed to be a few issues that were different depending on the tv model.
At any rate - what software are you using for playback? I did find that certain software wasn’t outputting hdr (properly).
My current setup is kodi frontend with mpc-hc and madvr in backend. It seemed to be the easiest way to get hdr to work for me - but I’m fairly certain that was down to my tv and the drivers at the time, I don’t know if things have improved (or got worse). As far as I can tell I don’t have greyed out colours, I have done a few comparisons between it and my uhd player.
