4k Screen in my future

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subeveant
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4k Screen in my future

Post by subeveant » Wed Jun 10, 2020 10:06 pm

Our HD / 2K plasma is dyeing so I've started to research replacements which will be, of course, 4k and with HDR10 support (currently leaning towards the Vizio PX75-G1 if it makes a difference). My current front end is a small form factor pc (I don't even remember the cpu / gpu) running 0.29.1+fixes; I've customized it to have integrated Netflix / Amazon Prime Video / Disney+ through the chrome kiosk and hacking some of the files. I also have Kodi installed on the box as it does playback better in some situations (such as imperfect cable card captures with audio drops).

Kodi as a mythtv frontend has had problems and seems to be high maintenance, but then I'm not current on Kodi either.

SOOO ... what should I be looking at to replace the SFF hardware? The Vero 4K+ looks very nice but it seems I wouldn't be able to install mythtv frontend on it, or chrome etc. And would be limited to vanilla Kodi.

Some NUC or the like would presumably work, though it seems that for both MythTV and Kodi "full" 4K support is at least a major revision away, especially for a linux host.

Any specific thoughts or recommendations would be greatly appreciated. And yes, I (already) have 4K sources.

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mark_k
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Re: 4k Screen in my future

Post by mark_k » Thu Jun 11, 2020 11:21 am

So the holy grail of full 4k HDR support and small form factor:)

Some technical detail below but If you want to future proof yourself against future developments, I would recommend a newer NUC or Intel/AMD based mini-itx system. If you're feeling brave - maybe one of the Android TV boxes running linux.

The honest truth is no MythTV build will currently give full/true HDR support - though it is a target for 0.32; and if we get there, it will likely be limited to certain vendors/chipsets/OSs.

In terms of hardware choice, it will be dictated by support for the various elements that need to be in place for 'proper' 4k HDR. I work on the basis that the following are needed:-

Display frame rate switching
4K resolution support
Colourspace handling
10 bit display
HDR signalling to the display

Ideally HEVC (with 10bit support) hardware decoding would be available - but software decoding will work if the CPUs have enough grunt.

Another thing to be wary of is 4k@60Hz support - my main development machine for VAAPI is a Coffeelake based system. This currently handles everything I can throw at it - BUT it will only support 4k@30Hz - which is disappointing. There are some motherboards that have an internal HDMI to display port adapter that will support 60Hz (google is your friend). I believe this is better for the newer Icelake chipset - but those don't seem to be readily available yet. Not sure about NUCs and/or AMD.

Display frame rate switching - this is currently fully supported on linux desktop and macos. It currently does not work on Android (though I have a patch to add it) and on linux without X (DRM) there are limitations (can only change the frame rate - not the resolution).

4k resolution - this is the easiest. Currently supported everywhere but Android. Qt's Android code 'virtuallises' the display so will currently always use a 2k resolution even if the display is running at 4k. Again, I think there is a fix but haven't had a chance to test.

Colourspace handling - This should be handled in 0.31 where possible. That includes software decoding, VAAPI (with DRM support), NVDEC, Videotoolbox (macos) and some of the more experimental linux hardware decoders. It does not work with VDPAU and some older OpenGL implementations and *probably* works with Android (Android tends to do its own thing - and it will vary depending on the hardware).

10 bit display - this is notionally supported on the linux desktop though it's been a while since I've tested it. It is still reported as breaking various desktop applications. MythTV should seemlessly render to a 10bit display if available. Android is again a bit of an unknown, as is macos. Linux without X won't currently work due to Qt limitations.

HDR signalling - this is the deal breaker everywhere. I'm not up to date on Linux kernel support. The two possible solutions are Linux with DRM and a re-write of the Android rendering code -- see below

So the possible routes to full HDR support in 0.32 are:-

- writing a custom Qt platform plugin for linux DRM support. This would give us full control of display resolutions, frame rates, colourspaces, depth and the ability to signal the correct HDR metadata to the display. It's not a simple undertaking though. That would likely work with most linux GPUs that have open source drivers - so I doubt it would work in Nvidia - but opens up some nice possibilities with Intel NUCs, Intel/AMD min-itx systems and probably some of the small, cheap SoCs that are around (see minimyth2 for some bleeding edge support for these devices). Given that this route uses linux without X/desktop, it will limit the ability to use other applications like Chrome etc.

- re-write the Android video rendering to use 'protected path'. Android only supports displaying HDR when using the copy-protected rendering pathway. I'm not entirely sure how feasible that is for MythTV - it is a very different approach to the current code and would require significant work.

It's also worth mentioning that there is work in progress to add tonemapping support for HDR material - which allows a reasonable rendering of HDR material on non-HDR displays (or displays where HDR has not been signalled).

Lost Dog
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Re: 4k Screen in my future

Post by Lost Dog » Thu Jun 11, 2020 2:53 pm

mark_k wrote:
Thu Jun 11, 2020 11:21 am
So the holy grail of full 4k HDR support and small form factor:)

Some technical detail below but If you want to future proof yourself against future developments, I would recommend a newer NUC or Intel/AMD based mini-itx system. If you're feeling brave - maybe one of the Android TV boxes running linux.

<snip>
Wow.... that was a fantastic post! Thank you for all the info!

I've not taken the jump to 4k / HDR yet but I'm needing to update my current video card (GT430) as it's not supported by recent drivers and it does not support h.265. The area I live in will have ATSC3.0 going live next month and I have the new ATSC3.0 HDHomerun on order. All the h.265 samples I've played looked like a slideshow due to the 10 year old AMD CPU in my HTPC.

I'd like to (somewhat) future proof my setup so when I do go 4k / HDR I'll be set. It seems from your post that MythTV has a tentative roadmap to support 4k HDR but it's a way out... That's fine, a new TV purchase is a way out too :D

Thanks again for taking the time to write all that!

subeveant
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Re: 4k Screen in my future

Post by subeveant » Fri Jun 12, 2020 3:08 am

Thank you so much mark_k, and all the others that have contributed (back when it was on gossamer threads) and the ffmepeg people and the kernel people and more. I love mythtv; more so as I have young ones to raise and want to curate screens to the extent possible.

It is gratifying to know that what I chase is in fact, the (current) holy grail. I've been at this for quite a while and less active than I used to be :)

It occurs to me that I probably want something that will (eventually) support hardware AV1 decoding which might be ... the next Intel "lake" or other.l +1 On lost Dog, your response was/is very helpful!

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mark_k
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Re: 4k Screen in my future

Post by mark_k » Sat Jun 13, 2020 10:54 am

Lost Dog wrote:
Thu Jun 11, 2020 2:53 pm
mark_k wrote:
Thu Jun 11, 2020 11:21 am
So the holy grail of full 4k HDR support and small form factor:)

Some technical detail below but If you want to future proof yourself against future developments, I would recommend a newer NUC or Intel/AMD based mini-itx system. If you're feeling brave - maybe one of the Android TV boxes running linux.

<snip>
Wow.... that was a fantastic post! Thank you for all the info!

I've not taken the jump to 4k / HDR yet but I'm needing to update my current video card (GT430) as it's not supported by recent drivers and it does not support h.265. The area I live in will have ATSC3.0 going live next month and I have the new ATSC3.0 HDHomerun on order. All the h.265 samples I've played looked like a slideshow due to the 10 year old AMD CPU in my HTPC.

I'd like to (somewhat) future proof my setup so when I do go 4k / HDR I'll be set. It seems from your post that MythTV has a tentative roadmap to support 4k HDR but it's a way out... That's fine, a new TV purchase is a way out too :D

Thanks again for taking the time to write all that!
Your welcome.

I should probably just clarify for anyone who stumbles upon this thread - MythTV is perfectly capable of decoding and playing 4K content already (including 10bit), either through software decoding or hardware assisted (vaapi, nvdec, vdpau, videotoolbox, mediacodec, v2l2_m2m etc). Likewise it will handle frame rate matching, colourspace conversions etc etc.

The only significant problem is the HDR element - and more specifically signalling of the HDR metadata to the display.

Regards
Mark

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mark_k
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Re: 4k Screen in my future

Post by mark_k » Sat Jun 13, 2020 10:58 am

subeveant wrote:
Fri Jun 12, 2020 3:08 am
It occurs to me that I probably want something that will (eventually) support hardware AV1 decoding which might be ... the next Intel "lake" or other.l +1 On lost Dog, your response was/is very helpful!
I think you may be waiting a while yet for hardware AV1 decoding - I don't see any reference to other than SoCs.

Thanks and regards
Mark

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Re: 4k Screen in my future

Post by bobmyth » Fri Jul 03, 2020 12:22 am

@mark_k: I stumbled upon your thread. This may be a silly question: If broadcast contains HDR will mythtv still play the stream without the HDR information?

My current system is an i3-2100T with an Nvidia GT730. I am preparing for 4k/UHD broadcasts as well. Does anyone have know where we can get some demo clips to evaluate my current system or do I need to order my 10th generation NUC now?

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mark_k
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Re: 4k Screen in my future

Post by mark_k » Wed Jul 08, 2020 9:36 pm

bobmyth wrote:
Fri Jul 03, 2020 12:22 am
@mark_k: I stumbled upon your thread. This may be a silly question: If broadcast contains HDR will mythtv still play the stream without the HDR information?
Yes - streams will still play even if HDR is not fully supported. The results may not be the best however - depending on the content. There is a little in the release notes:-

https://www.mythtv.org/wiki/Release_Not ... R.29_Video

The only progress on that front since 31 was released is some initial tonemapping support - though it is far from complete.
My current system is an i3-2100T with an Nvidia GT730. I am preparing for 4k/UHD broadcasts as well. Does anyone have know where we can get some demo clips to evaluate my current system or do I need to order my 10th generation NUC now?
I suspect that system will struggle - as I don't *think* the GT730 supports HEVC or HEVC Main 10 decoding - which is the 'standard' HDR broadcast codec (though some samples are VP9).

Probably the best site for clips is:-

https://kodi.wiki/view/Samples

For HDR material, you'll probably need to follow some of the links.

Hope that helps,

Regards
Mark

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