HDR Passthrough option
#1
Lightbulb 
I got KODI 19.3 running on a QNAP and it's working amazing in general.
Just one thing that is also very important to me and I guess many others having a HDR capable TV is the option of HDR passthrough.
Is this currently in (beta)testing or any idea about the timeline of making this available too?
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#2
(2022-01-11, 22:19)jdunbar8 Wrote: I got KODI 19.3 running on a QNAP and it's working amazing in general.

When you are running Kodi directly on a QNAP Nas, then you will need to ask the QNAP developers what the current status on HDR and/or passthrough is.
QNAP creates its own Kodi package for their NAS(es) with their own hardware tweaks, TeamKodi is not involved on such specific hardware builds/forks.
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#3
I see. But in general is there a HDR passthrough option available by KODI (on Linux), so that the QNAP developers can activate that setting in their build/release?
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#4
Passthrough is possible, but it also depends on the hardware (aka NAS) graphics/audio possibilities. Ask QNAP.
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#5
I guess currently we are mixing up "passthrough" (audio wise) and "HDR Passthrough" (video wise)

The first means, that you are able to use digital audio formats like DD, DTS, DTS-HDMA, DolbyTrueHD with Kodi connected to some AVR if it's capable of decoding such formats. 

The 2nd means, that the AVR passes the HDR signal through to the TV which is connected to the AVR if the playback device supports HDR playback and is connected to the AVR. AFAIK (and I might be wrong on that), HDR is currently not yet working with Kodi on Linux. Therefore it's also not available for Kodi on QNAP.

In the end it's all graphic drivers related and I guess a QNAP NAS might not support that in the very near future. A NAS should stay a NAS and not a playback device. But that's just my personal opinion
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#6
Hi @DaVu, thank you for making this more clear what I had in mind :-D
It's absolutely how you described. Currently audio passthrough works perfectly for all formats with KODI.
The other thing which is a really important as most movies, especially recent ones, are available in HDR and of course for all users having a HDR compatible TV.

Just for my understanding: isn't it actually less graphic driver dependent and demanding to have the NAS just pass the video / HDR signal through to the AVR/TV via HDMI?
(also it's already doing with the audio signal via passthrough) ?
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#7
(2022-01-12, 17:05)jdunbar8 Wrote: Just for my understanding: isn't it actually less graphic driver dependent and demanding to have the NAS just pass the video / HDR signal through to the AVR/TV via HDMI?

If you think twice about that question, I guess it's somewhat clear that everything video related is related to the graphics card, no? Wink At least in a bit. As said, I'm not too sure about the current situation of HDR support under Linux. But I'm at least 75% sure that it's graphics related. The rest might also be related to the kernel in use. You WILL need some kind of GPU to output anything. Even on the current Intel devices which do not have a dedicated graphics card, some GPU is build in. 

So if your NAS has a HDMI out, it also will have some kind of GPU. Otherwise a HDMI output doesn't make much sense Wink. If that GPU doesn't support HDR or if the driver in use which QNAP provides doesn't support it, your NAS won't be able to push those signals to the connected devices. 

I highly guess you have think different from the audio-passthrough option, where Kodi doesn't touch the audio at all and pushes that to the AVR. That said....there are still devices out there which do have a HDMI out, but can't do HD-audio (Raspberry Pi for example). 

Maybe @lrusak is able to tell more about the current HDR state on Linux in general. But as said. Even if it is supported on some specific hardware, that doesn't mean QNAP will ever support it. QNAPs goals are to build NASs. The video option is just a niche-thing. I, personally, would never place a NAS next to my amp and use it as a daily driver for playing videos. But that's your decision Wink
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#8
Lightbulb 
I do hope @lrusak can provide some insights into this
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#9
I am doing something along the lines of "HDR Passthrough" via regular 8bit RGB HDMI 1.4 by "faking" the color_primaries and color_trc metadata. This approach assumes that you set the color_primaries and color_trc in the display device manually to bt.2020/PQ, while kodi still assumes it is driving a regular bt709 display. In that situation by patching the media files metadata to bt709 (except color matrix), kodi will output the "unchanged" RGB data (although dithered down to 8 bit). This works quite well for me (using an Epson EH-TW7100 projector that I can manually set to bt2020 primaries and HDR10 dynamic range mode).

I have recently made a post about this: https://forum.kodi.tv/showthread.php?tid=366663. Unfortunately currently this requires patching all media files before playback, as there is afaik no way to disable the color space conversion of the RGB values from bt2020 to bt709 that kodi otherwise automatically does.

Maybe it would be worthwile to add a configurable setting into Kodi that disables the automatic conversion of the primaries, similarly to how it is already possible to disable the tonemapping from PQ to bt709.
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