How exactly does the MaxCLL/MaxFALL toggle work?

Also, according to mediainfo, the MaxDML and MaxCLL of the 4000 pattern are BOTH 4000. Apparently the LG OLEDs will always use the LESS of the two values. But I'm seeing both at 4000. Are you seeing differently in the file metadata?

I"m using the patterns from this link:

https://www.avsforum.com/threads/hdr10-test-patterns-set.2943380/

 

Whatever it's doing when the Zidoo toggle is off, it's not reading any metadata coming from the Zidoo because there isn't any.

Well, there is, but it's only Min/Max Master Display Luminance and that's 0.0005/1000 nits.

 

Ok - that would make sense - in the absence of MaxCLL/FALL it could be using MaxDML.

My files must be older - mine are MaxDML at 1000nits.

 

I think you just hit the nail on the head. The Zidoo isn't passing through MaxCLL/MaxFALL but the Zidoo IS still passing through mastering display luminance, right? So if the LG OLED uses the LESS of the two, then this happens:

- 1000 nit test pattern: MaxCLL is blank so TV would use 4000 nits, but since DML is 1000 nits, TV uses the lesser value and correctly chooses a tone curve of 1000 nits

- 4000 nits test pattern: MaxCLL is blank so TV would use 4000 nits, which is actually correct for this test pattern. Also DML is 4000 nits so TV uses 4000 nits

- 10000 nits test pattern - this is the only one that doesn't make sense to me: MaxCLL is blank so TV would use 4000 nits, and MaxDML is 10,000 nits. It SHOULD use the lesser of the two and use 4000 nits since that's the fallback for MaxCLL but it seems to still choose a 10000 nit tone curve correctly, so perhaps if MaxCLL is blank, it just defaults to MaxDML?

What do you think? Am i close? Ha. Maybe the TV just simply uses MaxDML whenever MaxCLL is blank. I am really not sure. Either way it seems like the TV is actually reading metadata!

 

Yeah - very close!

I think it's just using MaxDML in the absence of MaxCLL rather than the in-built default.

 

Nice! Yea, I'll have to read more about it, but I THINK that matches what is being talked about in the below thread, if you're interested. I think that is the 2022 LGs, so the C2/G2, but I assume it acts the same as the C1/G1.

https://www.avsforum.com/threads/20...gs-no-price-talk.3242257/page-5#post-61706365

 

@Markswift2003 Hey I wanted to get your opinion on something, since it is related to this.

I bought a 27GR95QE-B which is LG's new 27" OLED 240hz gaming monitor. I took a look in the service menu (used the service remote that works on the C1) and found some interesting results to say the least.....this is related to the maxcll and tone mapping discussion we're having. If you dont' mind, would you let me know your thoughts? I'm particular interested in why Cyberpunk locks the monitor to a 500 nit tone curve. Very weird indeed! What is most interesting is that the monitor will show you the REAL TIME tone curve/maxcll being read/used! The C1 does NOT show this information. I did not expect this monitor to actually communicate metadata with Windows.

https://www.avsforum.com/threads/i-...e-menu-of-a-27gr95qe-b.3273378/#post-62498695

 

You'd only want to lock to 500nits if the source wasn't going to go above than or you didn't care about any content above that.

But it also depends on the display - if the display is capable of going above 500nits there's absolutely no point at all in doing that.

For example, with your display, according to the Dolby Block, it's capable of 775nits, so anything up to 775nits doesn't need any tone mapping at all, so you certainly wouldn't want set it to start to tone map at 500nits.

But people do like to fiddle about with things...

 

The thing is that I don't have control over the tone curve, or at least I don't think so? What I am seeing is simply displaying the current tone curve that the panel uses. So for AutoHDR games and games that respect system level calibration, it shows a tone curve of 603. Cyberpunk shows 500. Doom eternal shows 1000. RE7 shows 10000, but HDR is completely screwed up in that game so I'm ignoring this one.

It is adapting the tone curve based on maxcll metadata, which Vincent from HDTVTest mentioned when he reviewed this panel. What is freaking weird is why it chooses 500 for cyberpunk. But then again, if a game was going to have weird ass things going on in HDR, it would be Cyberpunk. That game is the most buggy mess of programming I've ever seen in my entire life.

EDIT: Gamer 1 in HDR has a peak brightness of around 650 btw. Gamer 2 can hit 900ish post-firmware update but colors are super wacky. Gamer 1 is the most accurate mode.

https://www.rtings.com/monitor/reviews/lg/45gr95qe-b

 

It is also possible that it's just a bug with the OSD and a tone curve of 500 actually means 600. Maybe 603 means 650. Idk. The reported maxcll nits are slightly different from what I measured doing other methods. So it's hard to tell if maybe 500 is "right".

 

You might be over thinking this

 

Sir, I overthink everything, so yes, I am definitely overthinking this. I just figured understanding how tone mapping works will be helpful for other things down the road . I just wish all monitors had HGIG....considering this is an LG monitor, the lack of HGIG is very very stupid. All of their TVs have it!

 

You're absolutely right - understanding how this stuff works is incredibly helpful and incredibly useful.

This page is well worth a read - it's probably the best explanation of what HDR is (and isn't!) that I've seen:

https://www.lightillusion.com/what_is_hdr.html

You'll be buying an HDFury soon LOL.

 

I actually have the HDFury AVR Key. I just use it to split audio/video from the Zidoo since my receiver is 1080p and from 2009 lol. So audio goes to AVR, and video goes to the TV. I looked into their other devices but they are very expensive! Btw, I am going to test your older 4000 maxcll 1000 nit MaxDML file since I thnk that should basically confirm what's going on. Will report back when I have an update!

 

They are very expensive. But they are very cool

 

@Markswift2003

Ok I got to the bottom of it. Below are my findings for LG OLED TVs (at least as of the C1)



MaxCLL/MaxFALL toggle OFF in Ziddo: Only MaxDML matters. TV ignores any ovverrides I put in for the MaxCLL and only cares about MaxDML



MaxCLL/MaxFALL toggle ON in Ziddo: Both MaxCLL and MaxDML matter in this scenario. The TV will choose the LESSER of the two values.



So basically if the TV has NULL for MaxCLL for whatever reason, it only cares about MaxDML. If it has a value for MaxCLL, it will use whichever is LOWER.



I can finally close this mystery! Hopefully this helps anyone else who was curious and searches for an answer to this here.

 

I'd hope that wasn't the case!

MaxMDL is just the spec of the mastering monitor, nothing to do with content, and ok, in the absence of HDR metadata there is a tiny bit of logic in using it as a max luminance value, but if MaxCLL/FALL are present, these are the actual values calculated from the content pixel levels and there's no way MaxMDL should have any impact on those figures whatsoever.

Unfortunately in the early days, HDR and HDR metadata as defined by the IEEE was very misunderstood and all sorts of assumptions were made - hence my old Samsung (very incorrectly) only uses MaxMDL for tone mapping and you even saw titles with MaxMDL set to 10,000nits which even these days is not possible!

I'd hope that a display such as the C1 (and remembering that Dolby only recommend LG displays to test DV in a domestic scenario) would behave themselves!

 

HDR is am absolute cluster____, to say the least, lol. I think 99% of people see the HDR logo and think "nice i'm good" but actually have settings completely wrong or aren't getting the correct image.

 

Does the metadata passthrough option have anything to do with dolby vision?

 

No, nothing at all.