Why 24fps is not enough for HDR movies

[Rasmus Larsen]

Our review of LG CX is online. LG CX is the 020 successor to the 2019 LG C9. In addition to 4K, HDMI 2.1, and webOS, LG CX features Filmmaker Mode, HGiG Mode, three VRR systems, and more.
Link: https://www.flatpanelshd.com/review.php ... 1585020920

If you have questions please use this thread.

Enjoy.

[Ben Ong]

Hi,

I saw that you are saying Dolby Vision IQ was implemented in C9, may i know which function is that? does c9 has ambient light sensor?

[rons23]

So is the LG CX worth the $700 increase over the C9, or should I just go with the C9

[jubuttib]

Could you confirm whether the TV does or doesn't support 4K @ 120Hz over HDMI 2.0 by using 4:2:0 chroma subsampling on the PC, like Samsung does? An LG representative (Neil Robinson, senior director, strategic projects, LG USA) said in an interview, that the CX would support 4K@120Hz over HDMI 2.0, while the C9 would only ever support it over HDMI 2.1.

[Tabris]

Are you sure about no HDR support via G-Sync? Because Nvidia lists both the 2019 as well as 2020 models as HDR compatible and at least from what I've seen on multiple forums the 2019 models do work with G-Sync and HDR simultaneously. Of course you need an HDMI VRR compatible Nvidia GPU (RTX 20xx or GTX 16xx), anything else won't work before HDMI 2.1 cards arrive.

https://www.nvidia.com/en-us/geforce/pr ... ors/specs/

[Rasmus Larsen]

Hi,

I saw that you are saying Dolby Vision IQ was implemented in C9, may i know which function is that? does c9 has ambient light sensor?

We don't have access to an LG C9 at this time but as far as I recall it's part of the "AI Brightness" system.

Most mid-range and high-end TV from the past 10-15 years has a built-in ambient light sensor. In the past, it's been used for SDR. The new development is that it's now used for HDR, too. The next step (for future TVs) will be more advanced sensors (and multiple sensors) that can also determine ambient "color temperature" and more.

[Rasmus Larsen]

So is the LG CX worth the $700 increase over the C9, or should I just go with the C9

The worst time to buy a new TV is usually at launch - unless you buy last year's model. Prices for new TVs are artificially high.

I think C9 is a great choice if you need a new TV right here and now. If you can wait and you really wan CX then wait a couple of months. The price will come down considerably.

[Rasmus Larsen]

Could you confirm whether the TV does or doesn't support 4K @ 120Hz over HDMI 2.0 by using 4:2:0 chroma subsampling on the PC, like Samsung does? An LG representative (Neil Robinson, senior director, strategic projects, LG USA) said in an interview, that the CX would support 4K@120Hz over HDMI 2.0, while the C9 would only ever support it over HDMI 2.1.

We saw it demonstrated at CES 2020. At this time, we don't have the PC hardware to check (since we stopped doing PC monitor reviews we haven't invested much in our PC test suite).

But I'm not sure how much practical value it adds? 4K120 8-bit 4:2:0 over HDMI's TMDS signaling system is out of spec. It's not fit for the PC ecosystem (8-bit RGB levels) and not fit for the video ecosystem (10-bit HDR).

[Rasmus Larsen]

Are you sure about no HDR support via G-Sync? Because Nvidia lists both the 2019 as well as 2020 models as HDR compatible and at least from what I've seen on multiple forums the 2019 models do work with G-Sync and HDR simultaneously. Of course you need an HDMI VRR compatible Nvidia GPU (RTX 20xx or GTX 16xx), anything else won't work before HDMI 2.1 cards arrive.

https://www.nvidia.com/en-us/geforce/pr ... ors/specs/

Isn't that over HDMI VRR? There are 3 VRR systems for TVs at this time (HDMI VRR, G-Sync and FreeSync). Many similarities but also some differences.

Here's the officiel statement from LG that we received in regards to G-Sync a while back:
- "We use the G-Synch compatibility and at this time NVidia does not support HDR using this mode. "

Do you have a link to a forum discussion?

[jubuttib]

We saw it demonstrated at CES 2020. At this time, we don't have the PC hardware to check (since we stopped doing PC monitor reviews we haven't invested much in our PC test suite).

But I'm not sure how much practical value it adds? 4K120 8-bit 4:2:0 over HDMI's TMDS signaling system is out of spec. It's not fit for the PC ecosystem (8-bit RGB levels) and not fit for the video ecosystem (10-bit HDR).

Ah, so you did see it demonstrated, awesome!

And it does add a significant value to gaming, going from 60Hz on something like my B7 to 120Hz is a huge improvement (I had a Samsung Q950 for a week before returning it, and have tested a Q90 as well, and while they were absolutely horrible for computer use in many ways, the 4K 120Hz gaming experience was great). 8-bit color depth is still common in high refresh rate gaming, so it's not really a big difference compared to the norm, and the graphical quality losses of 4:2:0, while not insignificant, often aren't that much of an issue in gaming.

The biggest part of it is that you can enjoy the 120Hz right away, without waiting for and having to buy a new GPU as well (whenever those eventually come out), and since they do support HDMI 2.1 you'll be ready to move to that when you eventually do update your GPU. For someone like me, the C9 wasn't really a compelling upgrade, because I'd essentially only be getting G-sync (which, while great, isn't something I'm super concerned about), and would be stuck on 60Hz until new GPUs land and I could afford to get one of those too (1440p120Hz isn't really an interesting upgrade over 1080p120Hz of the B7). OK, the input lag is also better, but still.

The CX however really interests me, being able to run 120Hz at the TVs native resolution without other system changes would be a great upgrade to my B7. If C9 had supported it I would have bought one ages ago.

[Rasmus Larsen]

Great points! Thanks.

[lors]

Are you sure about no HDR support via G-Sync? Because Nvidia lists both the 2019 as well as 2020 models as HDR compatible and at least from what I've seen on multiple forums the 2019 models do work with G-Sync and HDR simultaneously. Of course you need an HDMI VRR compatible Nvidia GPU (RTX 20xx or GTX 16xx), anything else won't work before HDMI 2.1 cards arrive.

https://www.nvidia.com/en-us/geforce/pr ... ors/specs/

Isn't that over HDMI VRR? There are 3 VRR systems for TVs at this time (HDMI VRR, G-Sync and FreeSync). Many similarities but also some differences.

Here's the officiel statement from LG that we received in regards to G-Sync a while back:
- "We use the G-Synch compatibility and at this time NVidia does not support HDR using this mode. "

Do you have a link to a forum discussion?

This is NOT true. I'm playing with my 65C9 for five months now with HDR and VRR on PC with 2080ti. This was never a problem at all.

The review should be edited!

[Tabris]

Are you sure about no HDR support via G-Sync? Because Nvidia lists both the 2019 as well as 2020 models as HDR compatible and at least from what I've seen on multiple forums the 2019 models do work with G-Sync and HDR simultaneously. Of course you need an HDMI VRR compatible Nvidia GPU (RTX 20xx or GTX 16xx), anything else won't work before HDMI 2.1 cards arrive.

https://www.nvidia.com/en-us/geforce/pr ... ors/specs/

Isn't that over HDMI VRR? There are 3 VRR systems for TVs at this time (HDMI VRR, G-Sync and FreeSync). Many similarities but also some differences.

Here's the officiel statement from LG that we received in regards to G-Sync a while back:
- "We use the G-Synch compatibility and at this time NVidia does not support HDR using this mode. "

Do you have a link to a forum discussion?

These for example: https://www.avforums.com/threads/c9-e9- ... r.2259643/
https://www.reddit.com/r/OLED/comments/ ... s_working/
https://www.reddit.com/r/OLED/comments/ ... available/

Also, isn't G-Sync over HDMI basically just the standard HDMI VRR implementation and "G-Sync compatible" only means that Nvidia certified these displays to match their quality criteria like supported frequency range etc.?

I'm currently waiting for the 48" CX to use it as my dedicated gaming display for PC and consoles, so not having HDR supported while using G-Sync would be a huge bummer for me. Though I'm probably waiting for some actual tests with an HDMI 2.1 compatible GPU anyway.

[edit] Nvidia talks about HDR support for the 2019 models here too:

https://www.nvidia.com/en-us/geforce/ne ... lable-now/

[lors]

Are you sure about no HDR support via G-Sync? Because Nvidia lists both the 2019 as well as 2020 models as HDR compatible and at least from what I've seen on multiple forums the 2019 models do work with G-Sync and HDR simultaneously. Of course you need an HDMI VRR compatible Nvidia GPU (RTX 20xx or GTX 16xx), anything else won't work before HDMI 2.1 cards arrive.

https://www.nvidia.com/en-us/geforce/pr ... ors/specs/

Isn't that over HDMI VRR? There are 3 VRR systems for TVs at this time (HDMI VRR, G-Sync and FreeSync). Many similarities but also some differences.

Here's the officiel statement from LG that we received in regards to G-Sync a while back:
- "We use the G-Synch compatibility and at this time NVidia does not support HDR using this mode. "

Do you have a link to a forum discussion?

These for example: https://www.avforums.com/threads/c9-e9- ... r.2259643/
https://www.reddit.com/r/OLED/comments/ ... s_working/
https://www.reddit.com/r/OLED/comments/ ... available/

Also, isn't G-Sync over HDMI basically just the standard HDMI VRR implementation and "G-Sync compatible" only means that Nvidia certified these displays to match their quality criteria like supported frequency range etc.?

I'm currently waiting for the 48" CX to use it as my dedicated gaming display for PC and consoles, so not having HDR supported while using G-Sync would be a huge bummer for me. Though I'm probably waiting for some actual tests with an HDMI 2.1 compatible GPU anyway.

[edit] Nvidia talks about HDR support for the 2019 models here too:

https://www.nvidia.com/en-us/geforce/ne ... lable-now/

Don't worry, HDR with VRR is possible of course.

[Rasmus Larsen]

Are you sure about no HDR support via G-Sync? Because Nvidia lists both the 2019 as well as 2020 models as HDR compatible and at least from what I've seen on multiple forums the 2019 models do work with G-Sync and HDR simultaneously. Of course you need an HDMI VRR compatible Nvidia GPU (RTX 20xx or GTX 16xx), anything else won't work before HDMI 2.1 cards arrive.

https://www.nvidia.com/en-us/geforce/pr ... ors/specs/

Isn't that over HDMI VRR? There are 3 VRR systems for TVs at this time (HDMI VRR, G-Sync and FreeSync). Many similarities but also some differences.

Here's the officiel statement from LG that we received in regards to G-Sync a while back:
- "We use the G-Synch compatibility and at this time NVidia does not support HDR using this mode. "

Do you have a link to a forum discussion?

This is NOT true. I'm playing with my 65C9 for five months now with HDR and VRR on PC with 2080ti. This was never a problem at all.

The review should be edited!

So that’s HDMI VRR, right? Not G-sync? HDMI VRR supports HDR, yes.

The “unknown” that we are raising in the review in regards to HDMI VRR + HDR is compatibility with HDMI 2.1 (and the new FRL signaling system). We can’t explore that yet.