This was all a waste of money. - HDR on YouTube Rant

[perrinpages]

On 6/11/2022 at 11:54 AM, wswartzendruber said:

It looks like Google is doing interesting things with BT.2020->BT.709 colorspace conversion.

 

On the left side of the attached image is YouTube's automatic mapping from HLG (BT.2020 color with BT.2408 brightness levels) to BT.709 SDR. On the right side is native BT.709 SDR taken from the retail Blu-ray (in a blue case).

 

YouTube's interpretation of things seems to be making skin tones red.

 

hlg is an inferior hdr transfer function and was designed for broadcast, not streaming. it wasn't designed with a backward compatible color space either, so no point fussing about the colors not being dead on. there is no real reason why youtube can't serve pq hdr and sdr streams separately. 

[Brian McKee]

I have no doubt that HDR will just be "the" standard in the future, but as it matures and implementations become better it'll be a lot more mundane than people think. I think in 20 years a lot of the masters today will look insanely bad because of how overbaked they are. Not to mention with creative direction you might want to lose detail in highlights or shadows in your project, something people obsessed with HDR want to save.

 

Another thing to consider as tvs become better and brighter is just because you can make it painfully bright to look at doesn't mean I want to actually look at something painfully bright.

[dogwitch]

6 hours ago, Brian McKee said:

I have no doubt that HDR will just be "the" standard in the future, but as it matures and implementations become better it'll be a lot more mundane than people think. I think in 20 years a lot of the masters today will look insanely bad because of how overbaked they are. Not to mention with creative direction you might want to lose detail in highlights or shadows in your project, something people obsessed with HDR want to save.

 

Another thing to consider as tvs become better and brighter is just because you can make it painfully bright to look at doesn't mean I want to actually look at something painfully bright.

hdr was always the gold standard. (its over 100 years old) the issue has become the tech . it cost to show color correctly. every cog in the chain has to do it correctly is massive.

 

[Brian McKee]

17 minutes ago, dogwitch said:

hdr was always the gold standard. (its over 100 years old) the issue has become the tech . it cost to show color correctly. every cog in the chain has to do it correctly is massive.

 

I'm not sure what you're referencing here. Negative film stock has always had pretty good/excellent exposure latitude in the highlights (depending on the stock of course). But I've never heard anyone refer to it as HDR... Unless I'm missing something? I'm not well versed in cinematography history like I am with stills photography.

[dogwitch]

6 hours ago, Brian McKee said:

I'm not sure what you're referencing here. Negative film stock has always had pretty good/excellent exposure latitude in the highlights (depending on the stock of course). But I've never heard anyone refer to it as HDR... Unless I'm missing something? I'm not well versed in cinematography history like I am with stills photography.

both still photography and movie making. hdr has been the term to correctly take the image your seeing at that moment.

to do it correctly. it  has been a on going thing for over 100 years now .

[wswartzendruber]

On 7/2/2022 at 9:07 PM, perrinpages said:

hlg is an inferior hdr transfer function and was designed for broadcast, not streaming. it wasn't designed with a backward compatible color space either, so no point fussing about the colors not being dead on. there is no real reason why youtube can't serve pq hdr and sdr streams separately. 

That's sensible if you want them to grade twice. But HLG will let them grade once and have a consistent SDR representation automatically generated.

 

For all of the negative press HLG gets, it has one advantage PQ will never know: Being simple.

[wswartzendruber]

And to weigh in on the topic of film being HDR, we can compare mediums by listing their typical maximum white to reference white ratios in terms of perceivable brightness:

 

BT.709 SDR: 1.05x

Cinema: 1.22x

BT.2100 HLG: 1.29x

BT.2100 PQ: 1.72x

ST.2086 PQ: 1.97x

 

Note that I am using the PQ curve to model apparent brightness ranges for each medium.

 

With that said, Cinema is indeed superior to SDR while also being inferior to HLG.

[perrinpages]

On 7/6/2022 at 11:13 PM, wswartzendruber said:

That's sensible if you want them to grade twice. But HLG will let them grade once and have a consistent SDR representation automatically generated.

 

For all of the negative press HLG gets, it has one advantage PQ will never know: Being simple.

HLG color space is not backwards compatible with SDR, and YouTube will probably never implement a proper color space down convert. Why bother going through the hassle of an HLG workflow when HDR10+ is right there? PQ is the superior transfer function. YouTube implementing SDR down conversion using HDR10+ metadata would certainly yield better results than HLG.

[wswartzendruber]

13 hours ago, perrinpages said:

HLG color space is not backwards compatible with SDR, and YouTube will probably never implement a proper color space down convert. Why bother going through the hassle of an HLG workflow when HDR10+ is right there? PQ is the superior transfer function. YouTube implementing SDR down conversion using HDR10+ metadata would certainly yield better results than HLG.

People can yell that HLG isn't transparently compatible with BT.709 until they're blue in the face, but they can't argue with the results that modern players give:

 

Take a look at these JPEG images.

 

The only image there that's really struggling is the VLC output of the 20th Century Fox logo using the Linux OpenGL backend.

 

In any event, if YouTube supports using HDR10+ to provide even better conversion to BT.709, then what is the issue, exactly?

[wswartzendruber]

To be clear, I demonstrate the use of HLG here to get reasonable results, not ideal ones.

 

I maintain that LTT can export their videos to HLG, upload them to YouTube, and have YouTube do a reasonable job of BT.709 downconversion.

[Motifator]

I believe Youtube just compresses the hell out of most content, it also takes really LONG for the conversion and wait to end when you're uploading 4k material to YT. If you're uploading from something like a 4k handycam on a basis, it can be a lot of PITA.

Now I do have a Sony HDR TV I bought couple years back, and it does do HDR relatively well enough for what I paid towards it. It didn't do me anywhere near $2000 like one of the posters mentioned, not even half of it. Though finding content is still not an easy task, Netflix compression is even worse. Plus, CD content is pretty much dead in the water, which kicks my Xbox option out for me. I can't find the movies in UHD blu-rays, even when I do.. they are expensive.

When I first got the TV, I recall opening some HDR video on Vimeo and they had a decent implementation.

[wswartzendruber]

@LinusTech

 

Did you guys get anywhere with this? If anyone has questions about how these HDR formats work in principle, I can probably answer them.

 

I have little knowledge of how proprietary solutions implement them, however.

[LAwLz]

On 8/2/2022 at 5:27 AM, wswartzendruber said:

@LinusTech

 

Did you guys get anywhere with this? If anyone has questions about how these HDR formats work in principle, I can probably answer them.

 

I have little knowledge of how proprietary solutions implement them, however.

I wouldn't hold my breath. 

This is not the first time they get something very wrong, gets called out, says they will look into it, and then never address it again. 

Drumming up controversy gets more clicks than correcting it. 

 

Thanks for your posts though. Very informative. 

[wswartzendruber]

On 8/2/2022 at 11:48 PM, LAwLz said:

I wouldn't hold my breath. 

This is not the first time they get something very wrong, gets called out, says they will look into it, and then never address it again. 

Drumming up controversy gets more clicks than correcting it. 

 

Thanks for your posts though. Very informative. 

Eh, I'm not so much trying to call them out as I am trying to point them in a way that could work well for them.

 

HDR today is mainly dominated by PQ. PQ is objectively superior, but can be a complete pain when it comes to SDR compatibility.

 

Auto-converting BT.2100 HLG into BT.709 SDR is a fairly straight-forward process. Doing the same thing with PQ is...really up in the air and arbitrary. Even commercial 4K discs are mastered with varying brightness levels to the point where standardizing the process is a lost cause. I believe this is why YouTube lets you upload a custom LUT for each video.

 

EDIT: LMG could do PQ by placing reference white at 203 nits (broadcast standard) and MaxCLL wherever they choose, and then using a single LUT that gets uploaded with each video. The LUT would have to be calculated for the video's reference white level and MaxCLL value.

 

NOTE: Anything saying to place reference white at 100 is following the SMPTE standard, which in practice is used by home cinema. The ITU puts it at 203 nits, which is effectively the broadcast standard.

 

NOTE: "Putting" reference white and MaxCLL somewhere is most likely done during grading.

[MeatSafeMurderer]

On 7/3/2022 at 11:09 AM, dogwitch said:

hdr was always the gold standard. (its over 100 years old) the issue has become the tech . it cost to show color correctly. every cog in the chain has to do it correctly is massive.

 

This is a somewhat old thread but I felt it was important to correct this misconception because I saw it numerous times in here. HDR in photography and display HDR are not remotely the same thing.

In modern photography HDR is the process of taking multiple photographs at different exposure levels, then mapping them together in such a way to preserve detail in both light and dark parts of the image when finally outputting what essentially amounts to an SDR file. This is simply emulating something film and your eyes do naturally. Film is not "HDR" in that it has a vast gulf between light and dark values, it just responds to light in such a fashion that detail is often preserved. It's more akin to SDR tonemapping in the display world.

Display HDR describes, on a base level, something about a display's contrast ratio. A (good) HDR display is capable of displaying lots of detail in extremely dark areas that are extremely dark and bright areas that are extremely bright. This requires a display capable of deep inky blacks and bright searing whites simultaneously, along with a bit depth sufficient to maintain detail in both extremes. It does not need to map the dark values to lighter ones or light values to darker ones, as both film and digital HDR photography do, because it can display them natively and your eyes do the "mapping" instead.

[RoseLuck462]

I mean it’s YouTube, don’t gotta get that fancy