Vero 4K flat colours when sending to 709 4k projector

[dhts]

Hi, I’ve ripped my bluray and UHD bluray versions of Blade Runner 2049, but the UHD version colours look flat.

I’ve uploaded a log to https://paste.osmc.tv/ujomukipoq but new to all this so apologies if I’ve missed some information out or done something stupid.

Thanks.

[Chillbo]

Please use the search function of the forum…

This has been discussed at large: 4K content mastered with bt.2020 color space has to be converted to bt.709 as well as there has to be a conversion of HDR → SDR (as most 4K rips are in HDR), if the screen/projector can’t handle bt.2020 and/or HDR. There’s no standard for doing all of this and therefore not all results might be pleasing/perfect.

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[dhts]

Yes I read all those posts before posting.

The first is referring to 2160/59.94p 8-bit 4:2:0 Rec 2020 video, and a 2160/50p 10-bit 4:2:0 Rec 709 video not presumably standard 10-bit UHD bluray rec2020.

The second is about the HDR to SDR conversion being too dark, i.e. Not colourspace

The fourth says colour is OK.

The third might be relevant though it isn’t clear.

For sure HDR to SDR is challenging but I don’t see why colourspace conversion should be off.

Are responding as the official Vero 4k 5 year support ?

[Chillbo]

Just to have some more information:

Your projector supports 4K resolution, but only bt.709 SDR 8-bit video. Correct?

[dhts]

Yes to 4k, yes to only supporting bt.709, I believe it might support 10-bit.

[Chillbo]

@dhts

Yes to 4k, yes to only supporting bt.709, I believe it might support 10-bit.

Ok… And no HDR. So, there is no resolution downscaling happening like mentioned in some of the above threads, but the rest is more or less relevant (HDR → SDR/bt.2020 → bt.709 conversion and bitdepth conversion).

This is one thing related to bitdepth:

@sam_nazarko

We need to decouple colourspace from bit-depth in the future.

This means that any video that is a 4K UHD rip with bt.2020 colorspace and 10-bit HDR would be converted to 4K bt.709 SDR 8-bit, if the TV/projector can’t handle either bt.2020 or 10-bit.
So, there’s a conversion of HDR → SDR (bt.2020 → bt.709) happening as well as 10-bit → 8-bit. Sam is aware that bt.2020/10-bit and bt.709/8-bit are two sets linked together atm. That might change with some work in a future update (and might resolve some issues: e.g. bt.2020 8-bit or bt.709 10-bit output would be possible then).

Conversion of bt.2020 to bt.709 isn’t standardized and therefore not always perfect:

@sam_nazarko

There’s no official specification for dithering HDR (BT2020) to SDR (Rec 709).

So, obviously the way conversion of HDR (bt.2020) → SDR (bt.709) can be done is limited and not something that has been standardized. All conversion has to rely on trial and error/a compromise and the results may vary from source to source.

Conversion will happen as soon as your TV/projector can’t handle HDR/bt.2020/10-bit atm:

@sam_nazarko

Conversion should take place by default now.

There isn’t an exact science to conversion unfortunately, but there is room for improvement.

So, what you experience should be exactly what has been discussed before as this conversion isn’t standardized nor is it always perfect with any given source file. There might be some improvements coming some time in the future though (so you can tweak the conversion a bit to your liking):

@sam_nazarko

We can add some presets but from my perspective there will be limited support of HDR on SDR displays.

@sam_nazarko

In the future we may have some presets that can be chosen via the GUI.

[dhts]

As I asked before, are you replying on behalf of the official Vero 4K support ?

[Chillbo]

The quotes are all from @sam_nazarko. He’s the dev of OSMC and founder/boss I’m “just” a user like most here who are helping others out as well as they can…

@dhts

are you replying on behalf of the official Vero 4K support ?

Why so specific about this?

[dhts]

Because it’s a purchased product and part of the benefits promoted is 5 year software support. That’s why I went for this box.

It’s a little curious having to seek official support through an open forum but it’s a somewhat unique proposition all around.

Didn’t mean to seem ungrateful but at some point I’ll either need to fix the problem or I’ll need to return the box.

I’m sure Sam will be along at some point.

All the best.

[sam_nazarko]

You can get official support on the contact page as well.

We are far from finished with HDR and BT2020-BT709.

Sam

[Chillbo]

@dhts

Didn’t mean to seem ungrateful but at some point I’ll either need to fix the problem or I’ll need to return the box.

I’m sure Sam will be along at some point.

Sam is nearly always around and gives great support as soon as he can. Be sure of that! The support is definitely one of the best you’ll find for any piece of hardware.

BTW: 4K and HDR are working as advertised, conversion to SDR/different color space isn’t something advertised or standardised. Many are waiting for this and hoping for improvements, but we’re not demanding it. For most of us, the Vero 4k is an outstanding piece of hardware with great software support already as it is. And be sure that eventually, if @sam_nazarko promises something or says he’ll look into it, there will mostly be a fix/workaround or improvements.

[dhts]

Hi Sam, apologies if I’ve used the wrong mechanism for support. Do you want me to use that instead ?

Wasn’t sure if you were saying it is what it is for now?

It just seems odd it was so out that I noticed it without doing a comparison directly. Would you expect it to be like that or is there something about my setup which is highlighting a problem?

[Koldur]

HDR to SDR conversion doesn’t even work well on most UHD Blu-ray players. My Samsung player cannot do it. So, expecting the Vero to do this would be a bit strange. This is all very new ground to break and we are early adopters and these kind of things unfortunately are to be expected and no media player on the market today provides good HDR to SDR conversion.

I received mine yesterday, glad I did, glad I returned the Shield, it doesn’t even come close to the Vero when talking about 4K HDR playback!

[dhts]

…but we’re not talking about HDR to SDR, we are talking about 2020 to 709 colour conversion.

I’m not saying the screen looks dark.

[ActionA]

@dhts

It’s a little curious having to seek official support through an open forum but it’s a somewhat unique proposition all around.

Welcome to open source software my friend!

[sam_nazarko]

@dhts

Hi Sam, apologies if I’ve used the wrong mechanism for support. Do you want me to use that instead ?

No – you’re welcome to use either the forums or our direct contact (support@osmc.tv or sales@osmc.tv) if you prefer to avoid forums.

Most of our users utilise these forums because they will get very timely responses and support from other users as well. It’s of course optional.

We have some conversion matrices. I believe the SoC vendor are also making some improvements to this scenario.

Sam

[Koldur]

The same applies to that as well, you don’t seem to want to understand these kind of things and seem to be out on complaining.

[sam_nazarko]

Can you take a photo of your screen, and describe the problem in some more detail?

Sam

[dhts]

Picture emailed. Thanks Sam.

[nabsltd]

@Chillbo

BTW: 4K and HDR are working as advertised, conversion to SDR/different color space isn’t something advertised or standardised. Many are waiting for this and hoping for improvements, but we’re not demanding it. For most of us, the Vero 4k is an outstanding piece of hardware with great software support already as it is.

Agreed. I’m one who’d like to have this fixed, but it’s not critical in any way, because if you have a 4K-display, almost all of them handle HDR, and all should handle Rec.2020. The OP is one of the very few with a 4K display, no HDR and no Rec.2020.

Based on the output I see to a SDR, Rec.709 1080p display, I could have one of the display inputs re-calibrated to handle HDR sources from the Vero 4K, so it’s very close right now. It just needs a few tweaks