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Playing HDR in Theater desktop

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#1 Doofus OFFLINE  

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Posted 06 October 2018 - 12:14 AM

I thought I'd take the time to explain and possibly answer some questions on playing HDR content with Emby Theater desktop.

 

Can you play HDR movies with Theater desktop? Yes, you can.

 

This app uses mpv as it's player. It is a very capable player. The first thing to address, is that it doesn't play HDR content in the same way that many people are familiar with. Those using Windows to play HDR are familiar with the tight restrictions that are required to enable HDR in windows. Only in fullscreen, HDMI 2.0 or DP 1.4 etc This then allows the HDR metadata to be sent to the display, which then applies it to the output. You then see the display notify you that it's HDR10.

 

mpv doesn't send the metadata to the display. This loosens the restrictions in which you can play HDR content. You don't need to be in full-screen, and as long as the connection from the computer to the display has enough bandwidth, you'll be able to have the 10 bit color depth.

 

mpv uses algorithms to read the metadata and then render it to the video output. By using this, the metadata isn't required to be sent to the display. So you will not see the HDR10 notification on your display. 

 

Here is a link to what the HDR standards, are.

 

If you were to look at the details in Mediainfo, you would see something like this.

 

5bb8327a758fd_Snapshot_52.jpg

 

mpv has a default configuration for this. If it doesn't suit for viewing pleasure, there are a number of ways to adjust the output.

 

Here is some information from one of the mpv developers on why they use this approach.

 

5bb835a91ccb7_Snapshot_53.jpg


Edited by Doofus, 22 October 2018 - 09:40 PM.

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#2 Luke OFFLINE  

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Posted 06 October 2018 - 12:30 AM

Great info, thanks !



#3 PrincessClevage OFFLINE  

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Posted 06 October 2018 - 05:23 AM

I thought I'd take the time to explain and possibly answer some questions on playing HDR content with Emby Theater desktop.

Can you play HDR movies with Theater desktop? Yes, you can.

This app uses mpv as it's player. It is a very capable player. The first thing to address, is that it doesn't play HDR content in the same way that many people are familiar with. Those using Windows to play HDR are familiar with the tight restrictions that are required to enable HDR in windows. Only in fullscreen, HDMI 2.0 or DP 1.4 etc This then allows the HDR metadata to be sent to the display, which then applies it to the output. You then see the display notify you that it's HDR10.

mpv doesn't send the metadata to the display. This loosens the restrictions in which you can play HDR content. You don't need to be in full-screen, and as long as the connection from the computer to the display has enough bandwidth, you'll be able to have the 10 bit color depth.

mpv uses algorithms to read the metadata and then render it to the video output. Perceptual Quantization (PQ) is what is primarily used for this. By using this, the metadata isn't required to be sent to the display. So you will not see the HDR10 notification on your display.

Here is a link to what PQ is, along with the other standards.

PQ is part of the metadata in the HDR content. If you were to look at the details in Mediainfo, you would see something like this.

5bb8327a758fd_Snapshot_52.jpg

mpv has a default configuration for this. If it doesn't suit for viewing pleasure, there are a number of ways to adjust the output.

Here is some information from one of the mpv developers on why they use this approach.

5bb835a91ccb7_Snapshot_53.jpg

does this mean mpv can not play Dolby. Vision ? As I understand the benefit of Dolby vision is gained through the sending of metadata

#4 Doofus OFFLINE  

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Posted 06 October 2018 - 11:04 AM

DV comes with it's own set of troubles. It will play them, but mapped to 8bit. There are very few devices that support DV. And only a few video containers. Last I read, DV needs to be dual layered. I have a DV file, and while my display supports it, I have no way to play it, directly. Not even the display's own app, will play it. I think DV will go the same way as betamax, and never be widely used. With HLG and HDR10+ on their way, they are more likely to be widely implemented.

 

UPDATE

 

I hadn't tested DV in a while, but improvements have been made. mpv played my test file with 10 bit color depth.


Edited by Doofus, 06 October 2018 - 12:38 PM.


#5 Doofus OFFLINE  

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Posted 06 October 2018 - 01:26 PM

It looks like jeeb is working on HDR passthrough for windows.

 

https://github.com/m...r/mpv/pull/5804



#6 stettler OFFLINE  

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Posted 16 October 2018 - 09:08 AM

Maybe I am wrong but it really mean that mpv can play HDR content but it kinda downsample it (or whatever you want to call it) to send a SDR signal to the TV/monitor. Yes, it's "supposed" to be optimized to emulate HDR but it still a lose of information. If it wasn't, then there would be no need of HDR in the first place: everything could just be released in optimized SDR for the same result.

 

Also, what isn't writen in that quote from the mpv developers is that the result is very near HDR if you provide the correct propriety of your display to mpv which nearly nobody is going to do as you need to be able to measure the brightness (mostly) of your display.

 

Imho, it's like saying a FHD TV can play 4K content just because it can downscale a 4K signal to 1080p. Yes, you are going to be able to watch a 4K movie on it. Yes, it may even be pretty good. But that won't be 4K.

 

The mpv developers explanation why they don't pass true HDR to the display device is that 1) Only D3D11 can do it so it's not cross platform compatible 2) They think that their resampling is good enough

 

If you want HDR, use VLC or MadVR as external player. They both use D3D11 to pass the information.



#7 Doofus OFFLINE  

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Posted 16 October 2018 - 10:36 AM

It's full 10 bit gamut. It isn't SDR. The only difference is as haasn explains, PQ is better suited for human visual system. If you force an 8 bit suface in MPV and play an HDR title, it looks like crap.

#8 stettler OFFLINE  

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Posted 16 October 2018 - 04:06 PM

Hmm, I don't know. PQ is not an alternative to HDR: It's one part of the HDR standard. HDR10 profile is PQ + 4:2:0 sampling + 10 bits color depth + Rec 2020 color space + metadata. You can't say that one replace the other.

 

As one of the mpv developers explained (dunno if it was haasn), to do HDR properly, you need to know the caracteristic of the device. The manufacturer knows them so they can render HDR correctly. mpv doesn't know them so you have to specify them to it to achieve the same kind of result.

 

Anyway, so what do you configure with mpv? You set Windows display to RGB, 12 bits, range 0-255. ET output range 0-255. And on the TV, 0-255 range and force the Rec 2020 color space? (at least for me, the color space stay on Rec 709 if I don't force it)



#9 Doofus OFFLINE  

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Posted 16 October 2018 - 04:18 PM

You don't have to configure mpv at all. All of those elements you're referring to, all get used by default. Have you never tried it? The stats reports all of that. PQ is just the transfer. Basically the same thing the display does, just slightly different tone mapping. That's the only difference. And you can change pretty much all of it, almost any way you want. If you don't want to use PQ, you don't have to. It's all configurable.

I adjusted my display the way I like it, then I do everything else through mpv.

Edited by Doofus, 16 October 2018 - 04:19 PM.


#10 Jdiesel OFFLINE  

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Posted 16 October 2018 - 04:27 PM

As one of the mpv developers explained (dunno if it was haasn), to do HDR properly, you need to know the caracteristic of the device. The manufacturer knows them so they can render HDR correctly. mpv doesn't know them so you have to specify them to it to achieve the same kind of result.

 

 

 

For example you need to know the displays brightness capability. If the target nits don't match the actual nits of the display you can get clipping or too dark of a picture. So either you need a calibration meter to determine the displays actual max brightness, adjust the target nits by trial and error, or pass the HDR metadata to the display and let the display determine how to process things based on how it was designed for. I prefer to pass the metadata personally.



#11 Doofus OFFLINE  

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Posted 16 October 2018 - 04:30 PM

And that is also configurable. In multiple ways.

#12 Doofus OFFLINE  

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Posted 16 October 2018 - 04:34 PM

For me, passing the metadata is a royal pain in the ass. I can't use it. And I prefer the picture that mpv puts out. I can control it, and still have HDR in a window. Which I have to be able to do.

#13 PrincessClevage OFFLINE  

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Posted 16 October 2018 - 04:35 PM

I’m not sure that the majority of end users will want to tweek and configure mpv to get the visual output accurate for their display, more like they will expect this to just accurately output HDR which sounds like HDR passthrough will achieve but not yet available in mpv

Edited by PrincessClevage, 16 October 2018 - 04:35 PM.


#14 Jdiesel OFFLINE  

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Posted 16 October 2018 - 04:39 PM

Also worth mentioning that some displays have their own features that require the HDR metadata. For example the LG OLED displays with "Active HDR" which: 

*LG’s ‘Active HDR’ function analyses content on a frame by frame basis in real time, to
determine metadata for the scene. This information is then used to adjust the HDR tone-curve
to match the content, on a frame by frame basis.

I don't have an LG display but I've heard that this feature really helps out with scenes that are too dark



#15 stettler OFFLINE  

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Posted 16 October 2018 - 04:47 PM

You don't have to configure mpv at all.

 

I didn't asked how to configure mpv. I asked how to configure Windows, ET and the display.

 

 

And that is also configurable. In multiple ways.

 

As Jdiesel wrote, yes it's configurable if you have the data but the average user won't have the hardware needed to measure those data in the first place. (and even if you have the hardware, it's awfully hard to get the correct data because HDR TV, and especially OLED, give results that vary depending on what is displayed. Ie, a small patch of color can be a lot brighter for a short time than if the same color is displayed on the whole screen)



#16 Doofus OFFLINE  

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Posted 16 October 2018 - 04:53 PM

That's the point. You don't have to tweak. For the average user, they won't see the difference. They just want to see HDR10 pop up and have no real understanding of what it is. It's only the people with light meters and specific knowledge that will want to make any adjustments. Which everyone does, anyway. But they just configure the display instead software. I've read about people buying displays from people that 'professionally' adjusted before they're delivered. It's a bunch of horses**t. I can do all of that and more with software.

A perfect example is the shield. It has almost no picture settings. The metadata is sent to the display, and you adjust the display to your preference and environment (most people have no clue how to do that). They see the HDR10 and they're done. Even if they did, the display doesn't have any where near the configurability of software.

#17 stettler OFFLINE  

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Posted 16 October 2018 - 05:37 PM

For me, passing the metadata is a royal pain in the ass. I can't use it. And I prefer the picture that mpv puts out. I can control it, and still have HDR in a window. Which I have to be able to do.

 

Understandable. But the HDR passthrough limitations you mentioned are not the result of implementation limitation. If HDMI 2.0 is needed, it's because HDMI 1.4 doesn't have the bandwidth for 4K + 4:2:2 + HDR @60Hz. You need nearly 18Gbps for that. The other reason is copy protection (HDPC). Naturally, if you are playing something that don't have protection, you don't have the same restriction. But Microsoft is assuming you are playing something legit and so have protection.

 

Perhaps I am wrong but I think you can get HDR even if you play a movie in a window. Microsoft only said that on "many" (not all) built-in display (not external display), you need the "streaming" video app to be in full screen. VLC can play HDR in a window.

 

Nvidia made an HDR API that can dynamically switch a TV to HDR or SDR based on the content. It is used by MadVR.



#18 stettler OFFLINE  

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Posted 16 October 2018 - 06:02 PM

It's full 10 bit gamut. It isn't SDR. The only difference is as haasn explains, PQ is better suited for human visual system. If you force an 8 bit suface in MPV and play an HDR title, it looks like crap.

 

Is that really true? On my beamer, it seems that mpv is playing the video in rec 709 color space and not rec 2020: If I force the beamer to rec 2020, the result is way off compared to playing the same movie with VLC or with a UHD bluray player (With VLC or UHD player, the beamer detect HDR and directly use rec 2020)



#19 Doofus OFFLINE  

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Posted 16 October 2018 - 06:19 PM

Understandable. But the HDR passthrough limitations you mentioned are not the result of implementation limitation. If HDMI 2.0 is needed, it's because HDMI 1.4 doesn't have the bandwidth for 4K + 4:2:2 + HDR @60Hz. You need nearly 18Gbps for that. The other reason is copy protection (HDPC). Naturally, if you are playing something that don't have protection, you don't have the same restriction. But Microsoft is assuming you are playing something legit and so have protection.

Perhaps I am wrong but I think you can get HDR even if you play a movie in a window. Microsoft only said that on "many" (not all) built-in display (not external display), you need the "streaming" video app to be in full screen. VLC can play HDR in a window.

Nvidia made an HDR API that can dynamically switch a TV to HDR or SDR based on the content. It is used by MadVR.


No, it's a condition that windows stipulates. It won't allow it unless it's full screen. That's what haasn was saying. I recently wrestled with it to see what it actually took to make HDR to pass through on windows. It was excruciating. If your PC is dedicated to only watching video, then sure. But that isn't my use case.

So all I've needed to do with mpv, is enable UHD 10 bit on my display, adjust the display settings for my environment....press play. All the other stuff is just because I'm a control freak :)

#20 Doofus OFFLINE  

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Posted 16 October 2018 - 06:22 PM

Is that really true? On my beamer, it seems that mpv is playing the video in rec 709 color space and not rec 2020: If I force the beamer to rec 2020, the result is way off compared to playing the same movie with VLC or with a UHD bluray player (With VLC or UHD player, the beamer detect HDR and directly use rec 2020)


I've switched between the shield and my HTPC, to compare the picture. Is there a difference? Of course, because I'm using PQ. But the difference is only really noticable to those who know what to look for and are actually looking for differences.





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