[joevt]

Did you get the HDCP-ON version or the HDCP-OFF version? You should have the HDCP-OFF version.

[joevt]

CAC-1115 has a male Mini DisplayPort connector. It is certified by VESA DisplayPort. It should be able to connect directly between your computer and display.

CAC-1120 has a female Mini DisplayPort connector. It is not certified but the quality is probably good enough. It requires a Mini DisplayPort cable to connect between this cable and the display – having two cables chained together can lower quality.

Get the CAC-1115 unless you have a special use case for the CAC-1120.

[joevt]

I did some tests with the CAC-1331 using 4096×2304 resolution. There were some issues with some timings. I suppose I could expect similar issues with 3840×2160 timings (I should do more tests and note the pixel clocks)

https://forums.macrumors.com/threads/m1-mini-22md4ka.2272647/post-29336435
https://forums.macrumors.com/threads/m1-mini-22md4ka.2272647/post-29342101
https://forums.macrumors.com/threads/mac-mini-hdmi-out-to-display-port-do-the-adapters-work.2274641/post-29378347

The disappointment here is that it can’t handle arbitrary pixel clocks.

[joevt]

macOS doesn’t support MST hubs for multiple displays. It will send out a signal which is used by all attached displays of the MST Hub. This duplication of the signal seems to be a feature of MST hubs: consider a basic DisplayPort 1.2 MST Hub with three outputs – macOS can output 4K 60Hz to that and get the image sent to three displays – There’s no way macOS can send three 4K 60Hz signals through DisplayPort 1.2, therefore it must be the hub that is doing the duplication (maybe with some prompting by macOS).

Now, with Windows, mirroring on an MST Hub is not the default. But if you enable mirroring, then maybe you get the same result as macOS – where the MST Hub is doing the duplication? You can test this using a similar setup described for the macOS case. If the output pixels per second is greater than the possible input pixels per second then you know the MST Hub is doing the duplication. The setup will be more difficult with the CSV-7300 because it support DisplayPort 1.4 and DSC so the input needs to have a higher pixel clock than the DisplayPort 1.2 case.

[joevt]

The CAC-1085 also works with HDMI 2.0 displays.

Is there any feature difference between the CAC-1080 and CAC-1085 in regards to HDMI 2.0b support? We can ignore DSC because DisplayPort 1.4 has more bandwidth than HDMI 2.0.

Maybe the CAC-1085 doesn’t do horizontal expansion (whatever that’s good for?) or some color transformations (like 4:2:2 to 4:2:0 which might be useful if your source is DisplayPort 1.2 which does not support 4:2:0 and the TV doesn’t support 4:2:2)?

[joevt]

The CAC-1080 uses four lanes of HBR2 to do 4K 60Hz. DisplayPort 1.2 supports HBR2.

DisplayPort 1.4 is required for HDR (but macOS can do HDR from DisplayPort 1.2 with some adapters? I can’t get HDR with Club-3D’s adapters from macOS whether I’m using DisplayPort 1.2 or 1.4)

DisplayPort 1.4 is required for 4:2:0 pass through.

DisplayPort 1.2 can do 4:2:2 pass through but not 4:2:0. But the adapter can do conversion from RGB to 4:2:0 so that shouldn’t matter if you need 4:2:0.

The CAC-1080 has this “In addition HDR with deep color up to 12Bpc at 4K 60Hz is supported through the conversion of RGB/YCbCr 4:2:2 over DP link to YCbCr 4:2:0 on the HDMI™ output with a horizontal expansion to CEA timings.” I don’t understand “horizontal expansion to CEA timings”. I understand that a timing involves a pixel clock, horizontal pixels, vertical pixels, horizontal blanking pixels, and vertical blanking pixels. Horizontal expansion seems (I am guessing) to mean that the pixel clock is increased to have more total horizontal pixels per line (the number of horizontal blanking pixels must be increased so that the horizontal scan rate remains the same). It would be nice to have some example numbers to explain what it’s doing. This horizontal expansion may cause a couple issues:

1) horizontal expansion may require a scan line buffer which may be limited to a certain number of pixels, so for example, maybe it can’t do more than 4096 pixels wide for wide screen displays (the product page says 4096 is the max so maybe this is why).

2) If it’s changing pixel clock for horizontal expansion, how does it decide when to do that? What if I want to do some arbitrary timing? How will it choose when to change my timing?

I may be totally wrong here. The other part of the context for horizontal expansion is the conversion from 4:2:2 to 4:2:0. But that is just removing chroma from every second line or averaging chroma between every two scan lines – I don’t see how “horizontal expansion” describes that are why it’s needed.

Reading the features section, it says “Horizontal expansion of Vesa CVT to CEA Timings (as per DP 1.4 spec)”. The DisplayPort 1.4 spec isn’t available online so I guess I’ll never know what this means. CVT timings (replaces GTF timings) are usually used by CRTs.

[joevt]

The CAC-1510 does contain a chip from Synaptics according to the DPCD info but I don’t know which chip. The older Startech DisplayPort 1.2 to DVI Dual Link adapter  also uses a Synaptics chip but it may be an older chip or it has an older firmware.

[joevt]

Why would the CAC-1510 have a MST DisplayPort Hub?

[joevt]

There aren’t any DisplayPort to HDMI adapters that support FreeSync or G-Sync or Variable Refresh Rate, is there? Only HDMI 2.1 displays can support that? No-one makes a DisplayPort to HDMI 2.1 adapter that support Variable Refresh Rate.

 

[joevt]

Even if the displays don’t have DSC (they are DisplayPort 1.2), the MST hub should be able to take a DSC input and decompress it for the DisplayPort 1.2 displays.

DP 1.2 is 17.28 Gbps.
DP 1.4 is 25.92 Gbps.

Adding an MST Hub does not increase the number of displays a GPU can support. NVIDIA GPUs are usually limited to 4 displays. AMD GPUs are usually limited to 6 displays.

For the refresh rate calculator, the Resolution is supposed to be width x height, not pixels x displays. To calculate what you want, you have to determine the max data rate for a display (DisplayPort 1.4 with DSC = 25.92 Gbps x 2 compression factor / 3 displays = 17.28 Gbps) which in this case is similar to DisplayPort 1.2. So use the refresh rate calculator to get the max refresh rate for 17.28 Gbps = 174.2 Hz which is very close to what you calculated.

The delay for the CSV 7300 should be small because it doesn’t need an entire frame to do DSC decompression.

[joevt]

The CAC-1332 was tested at  #212 

Apparently, it does transmit USB 2.0 data.

Seems kind of silly that Club-3D doesn’t know the capabilities of its own adapters…

[joevt]

I have one HDCP ON adapter marked “CAC-1510”. I have two of the HDCP OFF adapters – one is marked “CAC-1510” and the other has an updated label marked “CAC-1510 HDCP OFF”. My Apple Cinema 30″ display only works for a couple seconds with the HDCP ON adapter from a Mac mini 2018. Maybe different GPUs or macOS versions have different results?

[joevt]

Without DSC, DisplayPort 1.4 supports 4K 120Hz 10bpc 4:2:2.
If HDMI 2.1 doesn’t work, HDMI 2.0 supports 4K 120Hz 8bpc 4:2:0 (10bpc is required for HDR).

Does the CAC-1085 support 4:2:2 and 4:2:0? It doesn’t say on the product page.

The GTX 1070 doesn’t support DSC but the LG CX does support HDMI 2.1, so if 4:2:2 works, then you should be able to get 4K 120Hz 10bpc 4:2:2.

The 4K120Hz problem with Nvidia drivers – is that because of DSC (which the GTX 1070 doesn’t have) or the timing itself?

[joevt]

Good question. I looked at https://en.wikipedia.org/wiki/HDMI#Version_1.4
I guess the point is that it doesn’t require HDMI 2.0 which many laptops/desktops don’t have. I don’t know of any laptop/desktop with HDMI that has a version that is not at least HDMI 1.4.

HDMI 1.0 was limited to 165 MHz.
HDMI 1.1 added DVD-Audio but I think the CAC-1302 uses LPCM audio.
HDMI 1.2 adds support for arbitrary resolutions and refresh rates – this is important for displays that don’t use the HDMI 1.0 modes.
HDMI 1.3 adds support for 340 MHz. This is important for higher resolutions and refresh rates.
HDMI 1.4 adds 4K but these club-3d adapters can’t do that. It also adds new color spaces and 3D which I don’t think are important for VGA output.

[joevt]

Club-3d can’t fix this. The adapter reports support for DSC but the driver doesn’t support DSC? Talk to the people that created the driver. Does the Linux Nvidia driver support DSC? AMD added DSC support for Linux last year.

I have a question about the functioning of the CAC-1085 and HDMI 2.1. Is there a difference between HDMI 2.0 and 2.1 cables that the adapter can detect or does it have to test the four lanes for signal quality? Does the CAC-1085 change any info (DPCD or EDID) reported to the host depending on the connection or is all info expected to be in the EDID?

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