Sorry, I meant the above is the limit of HDMI 2.1. The DisplayPort 1.4 output on current GPUs without DSC can do 4K 120 Hz HDR 8-bit with dithering YCbCr444 / RGB, or 4K 120 Hz / 144 Hz HDR 10-bit YCbCr422.

No i have a 2080ti, so it will be using DSC, can the CAC-1085 transport 4K@120 4:4:4?

No i have a 2080ti, so it will be using DSC, can the CAC-1085 transport 4K@120 4:4:4?From Pittyh

I don’t see why not. Current DisplayPort 1.4 4K HDR monitors without DSC can already do 4K 120 Hz HDR at 8-bit with dithering YCbCr444 / RGB.

I don’t see why not. Current DisplayPort 1.4 4K HDR monitors without DSC can already do 4K 120 Hz HDR at 8-bit  YCbCr444 / RGB.From Monstieur

With DSC, the adapter may be able to do 10-bit.

No i have a 2080ti, so it will be using DSC, can the CAC-1085 transport 4K@120 4:4:4?

From Pittyh

With DSC, the 2080ti should be able to output 4k@120hz 4:4:4 (and more), but you need to make sure your display device also supports DSC. For example, the 2020 LGs don’t support DSC, while the 2020 Samsung TVs with HDMI 2.1 do.

Pretty sure any tv with a hdmi 2.1 port would support DSC, i have a LG C9

Nope, DSC is an optional feature in HDMI 2.1. Vincent Teoh did a video where he looked at the EDID of a C9, and it had no mention of inputs taking DSC, where as a Samsung Q80T did. Scroll to ~15:15.

With DSC, the 2080ti should be able to output 4k@120hz 4:4:4 (and more), but you need to make sure your display device also supports DSC. For example, the 2020 LGs don’t support DSC, while the 2020 Samsung TVs with HDMI 2.1 do.

From frisbfreek

It does not need DSC to output 4K 120 Hz HDR 8-bit with dithering RGB / YCbCr444. There’s no need for 10-bit and DSC for HDR.

HDR requires 10 bit.

HDR requires 10 bit.

From Pittyh

No it doesn’t. Consoles and Blu-ray players which output subsampled YCbCr420 need 10-bit to prevent banding. A YCbCr444 / RGB source with full colour sampling can perform dithering at 8-bit and surpass the perceived banding of even 10-bit. That’s why you can run HDR 8-bit RGB / YCbCr444 on a PC which is vastly superior to subsampled 10-bit in games and text.

Correct me if I am wrong, but shouldn’t DSC be only required between GPU and adapter?

The way I see it, to convert DP 1.4 to HDMI 2.1 signal you need more bandwidth than DP 1.4 can deliver in some cases, hence the need for DSC. From adapter to TV HDMI 2.1 should have enough bandwidth.

I don’t think the adapter is acting as a converter but rather a passthrough of DSC-compressed signal. Otherwise it wouldn’t be able to obtain 8k @ 60hz, as that resolution and framerate can’t be obtained with an uncompressed signal over HDMI 2.1.

Good point, but LG CX  with 40 gb, should be sufficient to get 4k 120 8 bits 4.4.4    though ?

at 8Bits thats correct but running with HDR will need 10Bits

Thanks, good to know the 2080ti and LG C9 will work 😀

So i can expect to leave my desktop on 4K@120 4:4:4 10 bit HDR  And should not get a lot of switching like this guy?

What do you set your NVidia CPanel to? RGB or 4:4:4 ?

Is 4K@120 and 4:4:4 option even available on nvidia cpanel?

Now answer my PM Please i need one !!!!

Haha can’t get one anywhere.

40 Gbps is enough to do 4K 120 Hz HDR 10-bit RGB / YCbCr444, which is a resolution supported by the C9 / CX according to LG. 8-bit should definitely work. Only 12-bit is not supported.

HDR requires 10 bit colour

HDR requires 10 bit colour

From Pittyh

No it doesn’t. Consoles and Blu-ray players which output subsampled YCbCr420 need 10-bit to prevent banding. A YCbCr444 / RGB source with full colour sampling can perform dithering at 8-bit and surpass the perceived banding of even 10-bit. That’s why you can run HDR 8-bit RGB / YCbCr444 on a PC which is vastly superior to subsampled 10-bit in games and text.

This adapter should allow 4K 120 Hz HDR 8-bit with dithering RGB / YCbCr444 on Windows which is satisfactory. Ideally it would allow 10-bit RGB / YCbCr444 so you don’t need to use 8-bit with dithering, but it’s not confirmed yet whether this works on the CX.

Yes HDR requires 10 bit colourspace.

Were talking 16 million colours vs 1 billion colours, you can’t call it HDR if it’s 8bit lol

Bottom line —8-bit video is completely incapable of delivering HDR as it is by default of limited dynamic range, regardless of what special metadata accompanies it. Claiming 8-bit HDR is like boasting 5.1 channel is Atmos Audio. A 10-bit signal is an essential minimum for HDR video, whereas 12-bit buys a ton of headroom and an even greater dynamic range.

Yes HDR requires 10 bit colourspace.

Were talking 16 million colours vs 1 billion colours, you can’t call it HDR if it’s 8bit lol

Bottom line —8-bit video is completely incapable of delivering HDR as it is by default of limited dynamic range, regardless of what special metadata accompanies it. Claiming 8-bit HDR is like boasting 5.1 channel is Atmos Audio. A 10-bit signal is an essential minimum for HDR video, whereas 12-bit buys a ton of headroom and an even greater dynamic range.

From Pittyh

You’ve been misinformed by marketing. All the points you listed are false. They’re “true” only for low quality 4:2:2 or 4:2:0 subsampled signals that Blu-ray players use. You cannot apply dithering to a subsampled signal. A dithered 8-bit signal is visibly superior to a subsampled 10-bit signal – no contest. Banding is equal or superior depending on the dithering quality. Colour resolution is superior, objectively and visibly, in text and graphics.

Displayport 1.4 has a bandwidth of 26Gb, why would this matter at all?

Ahaha, i think i’ll take his word over some random poster 😛 Sorry.

From Pittyh

He’s talking about 8-bit vs 10-bit in the industry i.e. 8-bit (typically 4:2:0) used for SDR vs 10-bit (4:2:0) used for HDR. This is the context in which those statements are true.

There’s no mention of RGB / YCbCr444 or dithering. An 8-bit RGB / YCbCr444 signal with dithering is superior to any subsampled (4:2:2 or 4:2:0) 10-bit image.

The range of values in a 10-bit signal is irrelevant. Talking about “stops” like a camera is meaningless. How values map to brightness is determined by the PQ EOTF and it’s irrelevant whether it came from a “big number” 10-bit value or a dithered 8-bit signal with alternating “small numbers”.

Number of colours (millions vs billions) is irrelevant. The colour perceived by the eye depends on the effective wavelength emitted by the display. The same wavelength corresponding to a discrete 10-bit value is achieved by a 10-bit signal on a 10-bit panel, a 10-bit signal on an 8-bit + FRC panel, or 8-bit with dithering RGB / YCbCr444 signal on a plain 8-bit panel. The downside to dithering / FRC is the temporal colour resolution is reduced in half, which is 60 Hz on a 120 Hz panel. Movies are 24 Hz, so there is no loss. On the desktop and in games, the eye cannot detect temporal colour change even at 60 Hz. It still displays 120 unique frames per second.

No worries mate, i don’t mean to be rude, but i don’t really care, all i want is windows 10 on my LG C9 running at 4K@120 in 4:4:4 or RGB, with HDR on. That’s all i want, it’s not much to ask  is it ? 😛

No worries mate, i don’t mean to be rude, but i don’t really care, all i want is windows 10 on my LG C9 running at 4K@120 in 4:4:4 or RGB, with HDR on. That’s all i want, it’s not much to ask  is it ? 😛

From Pittyh

You get HDR on Windows with 4K 120 Hz HDR 8-bit with dithering RGB, which is supported by the adapter, C9, and CX.

We don’t know if 4K 120 Hz HDR 10-bit 4:4:4 / RGB is supported by the adapter / CX at 40 Gbps / C9 at 48 Gbps, because it needs DSC at the DisplayPort 1.4 end, but it is indistinguishable from 8-bit with dithering so it doesn’t matter.

The concept of using dithering to convert an 8-bit signal to something that looks like 10-bit is interesting. However, I don’t think 8-bit + dithering is implemented by any current or planned sources, so isn’t it all of this moot? A better solution, especially now since HDMI 2.1 and DisplayPort 2.0 are around the corner, is to just increase your bitrate by 20% and go 10-bit. I doubt anyone would implement this dithering solution just to work within some old bandwidth constraints.

You get HDR on Windows with 4K 120 Hz HDR 8-bit with dithering RGB, which is supported by the adapter, C9, and CX.

We don’t know if 4K 120 Hz HDR 10-bit 4:4:4 / RGB is supported by the adapter / CX at 40 Gbps / C9 at 48 Gbps, because it needs DSC at the DisplayPort 1.4 end, but it is indistinguishable from 8-bit with dithering so it doesn’t matter.

From Monstieur

Think about this Adapter, it is Displayport 1.4 to HDMI 2.1. Displayport 1.4 is 32Gbps max bandwidth. HDMI 2.1 is 48Gbps max bandwidth. Therefore, the Adapter will always drop down the lowest common denominator to function. Which means it can only do 32Gbps max bandwidth (capped by the Displayport 1.4 spec). 

But still, 32Gbps is enough bandwidth to do 4k 144hz 10-bit 4:4:4 chroma with DSC. Or 4k 120hz 8-bit RGB without DSC. 

The concept of using dithering to convert an 8-bit signal to something that looks like 10-bit is interesting. However, I don’t think 8-bit + dithering is implemented by any current or planned sources, so isn’t it all of this moot? A better solution, especially now since HDMI 2.1 and DisplayPort 2.0 are around the corner, is to just increase your bitrate by 20% and go 10-bit. I doubt anyone would implement this dithering solution just to work within some old bandwidth constraints.

From frisbfreek

Windows 10 has supported 8-bit RGB / YCbCr444 with dithering for HDR since the beginning. It automatically uses dithering when running in a full colour sampling mode like RGB / YCbCr444. This is the ideal mode for HDR monitors over DisplayPort 1.4. The banding and colour gamut is indistinguishable from 10-bit YCbCr422, and you get full colour sampling with desktop quality text and graphics. Subsampling looks terrible on the desktop with fringing on everything.

It’s only consoles and Blu-ray players which force you to use 10-bit YCbCr420 for HDR.

Dithering cannot be applied to a colour sub-sampled signal, which is why you can’t get HDR at 4K 120 Hz 8-bit with dithering YCbCr420 on HDMI 2.0 on the CX. However you can do HDR at 4K 60 Hz 8-bit with dithering RGB instead of dropping down to 10-bit YCbCr422.

Max of what? the CX or the C9?

This is all very confusing, even the Club3d guys can’t give a  straight answer.

Can i do 4K@120 Hz with 4:4:4 HDR/10Bit on my 2080ti and lg C9 with the cac-1085?

It’s a pretty straightforward question, but everyone seems to give different answers.

If you want 10 bit 444, it’s going to be 98hz. 4k 120 will be 8 bit.

@Pittyh assuming your C9 doesn’t have DSC, you cannot do 4K @ 120hz 4:4:4 10-bit because that is beyond the bandwidth of DisplayPort 1.4. From what @Monstieur said, your best option within your bandwidth constraints is to use 8-bit + dithering, as this has the least impact on perceived quality (although I don’t know how to enable it exactly).

If your C9 has DSC then great you should be good to go, but the research so far suggests that it doesn’t. You might want to reach out to LG if you want a definitive answer.

Ok Cheers

Guess i will have to wait til the 3080 to unlock the full potential of the tv. I will still get the club3d cable though, because 8bit 4k@120 will still be good. 😀

For me 98hz is worth it, trust.

Nope, you’re not factoring in the 8/10 encoding rate in DisplayPort 1.4. This means that it uses 10-bits to transmit 8-bits of data. So your 32.4 Gbps max bandwidth turns into a 25.9 Gbps max *data rate*. This encoding is also separate from any blanking overheads.

I’ve actually worked on a Wasabi mango 4k 120. Those are the limitations.

But also if you look at the product page it states:

This product is SPECIFICALLY designed to work with the latest Graphics Processing Units (GPU’s) which supports DSC 1.2

and

With its DP1.4 DSC video compression technology, this adapter is able to convert DP1.4 video signals to HDMI™2.1, supporting video display resolutions up to 8K (7680 x 4320)@60Hz **

and 

** Please update your Graphic drivers on your PC and make sure that DSC1.2 is supported on your devices to support the these resolutions/refresh rates!

And on the nvidia 20 series wiki:

DisplayPort 1.4a with Display Stream Compression (DSC) 1.2

So 4k@120 with 4:4:4 HDR using DSC fits within the 25.92 limit. So does 4:2:2 

Only 20 series nvidia cards have DisplayPort 1.4a with Display Stream Compression (DSC) 1.2

Yep that’s exactly what happens, i’ve worked it out

Nvidia display port 1.4 HBR3 = 32.27gbit/s but with DSC -> fits in HBR3 25.92Gbit/s -> adapter then converts this 25.92Gbit/s signal to HDMI 2.1

So it’s your choice use 4:2:2 which disables DSC, and you get chroma subsampling (bad for pc text)

Or set 4:4:4/RGB and DSC kicks in and will compress the 32.27 to fit within the 25.92 limit.

They are both the same bandwidth and will fit into 25.92 – the max data output of dp1.4

Look at the dp1.4 HDR Video with Compressions table on wiki https://en.wikipedia.org/wiki/DisplayPort

@Pittyh, I’m not sure what your point is? The adapter will convert a DP 1.4 signal to an HDMI 2.1 signal; this signal can be uncompressed or use DSC. However, DSC won’t be used unless both your source can do DSC compression and your display can do DSC decompression. The adapter does NOT convert a DSC stream into an uncompressed stream.

If either your source or your display can’t do DSC, then you’re limited to 4K @ 120hz 4:4:4 8-bit for an uncompressed signal (and the limitation is on the DP 1.4 side).

If BOTH your source and display can do DSC, then you should be able to get higher resolutions/framerates/color depth, as DSC can do ~3:1 compression ratio. 8K @ 60hz is roughly 2x the data rate of 4K @ 120hz, so that’s possible, but only with DSC.

You stated you have a C9, so your display likely doesn’t support DSC.

The adapter does NOT convert a DSC stream into an uncompressed stream.From frisbfreek

Are you sure about that? product page says “With its DP1.4 DSC video compression technology, this adapter is able to convert DP1.4 video signals to HDMI™2.1”

Sounds to me exactly like what it is doing.

It supports DSC compression in the DP 1.4 stream input and HDMI 2.1 output, but it’s not claiming that it does the decompression.

Think about it: if it were converting DSC to non-DSC, it wouldn’t be able to support 8K @ 60hz. That resolution and framerate requires 49.6 Gbps uncompressed, but HDMI 2.1 only supports a 42.67 Gbps data rate. So how would it be possible?

FYI, here’s a data rate calculator in case you need it:

https://tomverbeure.github.io/video_timings_calculator

Amazon question about product.

Does this require a tv/screen that supports dsc, or is that just required for the source?

No it does not require the screen to support DSC the adapter will work as a decoder or bypass when the source is supporting it .

Interesting, still very vague though 😛

Also i sent an email to club3d and got this response:

Hi can you please clarify some details regarding the CAC-1085?

If I have a 2080ti and a LG C9

Can I enable 4K@120 hz with 4:4:4 Colour and 10bit HDR?

Or is it 8bit?

Does the adapter take the DP1.4a DSC signal and uncompress it to hdmi2.1?

So 25.92 Gbit/s signal from the video card to the adapter, uncompress then convert to 32.27Gbit/s hdmi2.1 from the adapter to the HDMI2.1 port?

There is a lot of talk and confusion going around, some clarification would be great 

Regards,

—————————
Hi ****,

Yes the adapter is able to support 4K@120Hz with 444 and 10Bit
The adapter is able to Bypass and Decode
It does note Encode DSC Compression

With the LG C9 the support for 48Gbps full HDMI is there. Please note that newer LG TV from 2020 does not support fully the 48Gbps but only 40Gbps so limitations might be on the supported devices.

We hope this answer your questions.

Best regards

Club3D Support

I was hoping this would convert the DSC and not use it passively (which is useless for us C9/CX owners) Oh well 4k/120Hz/422/10bit/HDR or 4k/120Hz/444/8bit/HDR dithering will have to do for now. Good to know that 422 works though, I’ve been worried it wouldn’t work because at 4k the TV won’t accept 420.

Hmm it’s now unavailable with no planned stock date. Hope they didn’t find a critical flaw!

https://www.amazon.com/gp/product/B08BC8LV3M/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

Finally in stock 🙂 Go ahead!

Why are you switching between HDR and SD? can’t you just turn on HDR in windows and leave it on?

Why are you switching between HDR and SD? can’t you just turn on HDR in windows and leave it on?

 

 

From Pittyh

If i’m in SDR and i turn on HDR in windows 10, the screen goes black. So i have to pull out the adapter’s power cable and put it back in again to get a picture on the screen. If I don’t do that, the screen stays black. The trouble is, many PC games do not support HDR. So then the game will automatically switch to SDR. Then that causes a black screen. And once again i have to unplug the adapter’s power cable and pop it back in again to get the screen to come back on.

The CAC-1085 feels very much like an unfinished prototype. I REALLY hates switching from HDR to SDR or from game to desktop (and vice versa).

How did you get 4k120hz RGB 10Bbit? I assume 444?

How did you get 4k120hz RGB 10Bbit? I assume 444?From net200777

No. The adapter is offering me 4k 120hz Full RGB @ 8-bit, 4K 120hz Full RGB @ 10-bit or 4k 120hz 4:2:2 Limited @ 8-bit/10-bit/12-bit. There is no 4:4:4 option and no 4:2:0 option.

But no matter which of those settings i choose, the damn thing is always losing signal and I am forced pull out the adapter’s USB power cable and plug it back in again to get an image back onto the screen. 

If you can get full rgb, you can also get 4.4.4 . ( this is the same, only that one is converted live )    SDR 10bits 4k 120 full rgb 444 is really good and I cant wait to receive my adapter.

Question for the owners,

Do you notice a difference in mouse lag / input lag switching from 1440p 120Hz   and 4k 120hz ?

Thanks!

Has anyone been successful setting a custom resolution? Specifically 4k 96-98hz 10bit 444?? It won’t accept it for me.

If you can get full rgb, you can also get 4.4.4 . ( this is the same, only that one is converted live )    SDR 10bits 4k 120 full rgb 444 is really good and I cant wait to receive my adapter.

Question for the owners,

Do you notice a difference in mouse lag / input lag switching from 1440p 120Hz   and 4k 120hz ?

Thanks!

From BricoDepot1987

The adapter is absolute garbage. It is constantly losing signal and giving me a black screen whenever i try to change any resolution settings in video game graphics menus. Sometimes I have to restart my PC just to get an image back on the screen. The CAC-1085 is a very flawed device and I wouldn’t be surprised if Club3D has to recall them all.

The adapter is absolute garbage. It is constantly losing signal and giving me a black screen whenever i try to change any resolution settings in video game graphics menus. Sometimes I have to restart my PC just to get an image back on the screen. The CAC-1085 is a very flawed device and I wouldn’t be surprised if Club3D has to recall them all.

From Ravenmaster

1.That has nothing to do with BricoDepot1987´s comment.
2. Club3d is designing Cabels and adapters to bring a signal from A to B, every issue that you have is caused by the software of A and B. The fact that you need to restart your PC instead the adapter is the proof.

3. Wait for software updates of A and B cant be so hard, right? So lets chill…

4. It is summer , so go outside and watch some ti..