CAC-1335 Problem

Updated on 14-09-2022 in Adapters and Cables.

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10 0 on 06-09-2022

Jim

I received a CAC-1335 yesterday from Amazon. I want to use it connect a HP Reverb G2 VR Headset to an Aorus 17X YD with an HDMI 2.1 connection to its RTX 3080 discrete graphics cards. The HR Reverb G2 has a DisplayPort 1.4 cable to connect to a PC. This adapter does not enable the connection. I plugged in the USB power first, then the adapter into the HDMI port on the laptop, then connect the DisplayPort to the adapter. The laptop recognizes that the headset is there and then the Windows Mixer Reality Program throws an error code 1-4. What am I doing wrong? The resolution of each eye of the headset is 2160 X 2160 and it runs at a maximum speed of 90 hz. Why does it not work? The same cable will connect to an older laptop with a mini-displayport connection to the discrete graphic card, so the cable it good.

1 0 on 06-09-2022

joevt

Does the headset appear as a display when used with the CAC-1335?

When connected to DisplayPort without the CAC-1335, does the headset present itself as a 4320 x 2160 display or as two 2160 x 2160 displays? Or the operating system might not show it as a display. I’ve never tried VR before so I’m not sure.

Can you extract the EDID(s) from the headset? Using AMD or Nvidia software? Or using CRU?

If it’s two 2160 x 2160 displays then it won’t work since that would require DisplayPort MST which cannot originate from HDMI.

I’m not sure the adapter was tested with any resolutions other than 3840×2160 or 7680×4320, so you should do your own tests if possible.

Do you have a normal display that you can test the CAC-1335 with? Can you create a 4320×2160 custom resolution for that display using AMD or Nvidia or CRU and test it without the adapter? I have a 4K display that can accept resolutions up to 4K120 or 5K60 or 6K50 or 8K30 as long as the pixel clock does not exceed ≈1080 MHz. Once you know you have a display that can support 4320×2160, you can test the adapter with that mode. You may need to recreate the custom resolution when you switch the connection from DisplayPort to HDMI port.

You said “The same cable will connect to an older laptop with a mini-displayport connection to the discrete graphic card, so the cable it good.” The CAC-1335 has DisplayPort, not Mini DisplayPort. Please explain exactly what is connected to the laptop (adapters, cables, display).

I would try this connection order: USB power, DisplayPort connection to display, HDMI connection to computer.

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Does the headset appear as a display when used with the CAC-1335?
When connected to DisplayPort without the CAC-1335, does the headset present itself as a 4320 x 2160 display or as two 2160 x 2160 displays? Or the operating system might not show it as a display. I've never tried VR before so I'm not sure.
Can you extract the EDID(s) from the headset? Using AMD or Nvidia software? Or using CRU?
If it's two 2160 x 2160 displays then it won't work since that would require DisplayPort MST which cannot originate from HDMI.
I'm not sure the adapter was tested with any resolutions other than 3840x2160 or 7680x4320, so you should do your own tests if possible.
Do you have a normal display that you can test the CAC-1335 with? Can you create a 4320x2160 custom resolution for that display using AMD or Nvidia or CRU and test it without the adapter? I have a 4K display that can accept resolutions up to 4K120 or 5K60 or 6K50 or 8K30 as long as the pixel clock does not exceed ≈1080 MHz. Once you know you have a display that can support 4320x2160, you can test the adapter with that mode. You may need to recreate the custom resolution when you switch the connection from DisplayPort to HDMI port.
You said "The same cable will connect to an older laptop with a mini-displayport connection to the discrete graphic card, so the cable it good." The CAC-1335 has DisplayPort, not Mini DisplayPort. Please explain exactly what is connected to the laptop (adapters, cables, display).
I would try this connection order: USB power, DisplayPort connection to display, HDMI connection to computer.

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Jim

JoeVT,

I tried to use the Nvidia Control Panel to view the EDID. I couldn’t find the information. So I download CRU. The details for the Windows Mixer Reality device, which is the HP Reverb G2, Is below. I am not sure what it means, but I hope you can understand it.

1 0 on 07-09-2022

joevt

Click the Export button and post the result. A copy of the hex bytes as text is sufficient. The info for the display modes is probably hidden in the CTA-861 or DisplayID extension blocks.

Is there only one HPN36C1 in the menu? That may indicate that it’s only one display device (SST instead of MST)

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Jim

Joevt,

There is only one HPN36C1 in the CRU listing of devices. I even deleted it with the device unplugged and connected it again so that it would refresh the EDID. I will put the Export file to this message. At full resolution i have read that the HP Reverb G2 should be 6048 X 3024. HP Inflates the resolution to make up for the corrections of barrel and pincushion distortion. There are settings where you can rescale the resolution but the above it the maximum. When I mentioned I had tested the displayport cable to be sure it was not a problem I was trying to convey that I know that cable and headset are working fine when connected to a mini-displayport on another other machine. They work fine, but it is a very slow frame rate.

00 FF FF FF FF FF FF 00 22 0E C1 36 67 54 E9 7F
08 1F 01 04 80 0B 05 78 0E CB A0 A3 55 4D 99 27
0E 50 54 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 6A A7 40 64 B0 A0 9E 50 32 04
22 04 6E 32 00 00 00 1E 00 00 00 10 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 10 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 10
00 00 00 00 00 00 00 00 00 00 00 00 00 00 02 19
02 03 1A 00 75 5C 12 CA 01 07 9D D6 23 E3 5C 6D
56 0C 9B 9C 6B 79 A9 F1 E5 9E 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 50
70 12 79 00 00 03 00 28 AB 61 01 88 DF 10 63 00
31 80 03 00 6F 08 73 00 0F 80 01 00 02 15 01 08
DF 10 63 00 31 80 03 00 6F 08 01 02 0D 80 01 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00 00 00 07 90

Thanks,

Jim

0 0 on 12-09-2022

Jim

JoeVT,

Does the EDID data from above give you any indication of the problem? When I closely read the specifications for the HP Reverb G2 it states that only DisplayPort 1.3 is required. Since this adapter supports DisplayPort 1.4 it should work properly. What are we missing?

Also in the specifications it says that resolution is 2160 X 2160 per eye so it makes a display of 4320 X 2160.

Please let me know what else we can check or debug.

Thanks,

Jim

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1 0 on 12-09-2022

joevt

The EDID has a 4320×2160 60Hz mode for HBR2 8bpc RGB/4:4:4 and a 90Hz mode for HBR3 8bpc RGB/4:4:4. There’s no 4:2:2 or 4:2:0 or DSC support. Both of those modes are in the DisplayID 1.3 extension block. The CTA-861 extension block only contains a Microsoft Vendor-Specific Data Block which identifies the device as a Virtual reality headset and assigns a UUID which I suppose can be matched with a UUID of a corresponding USB device for position tracking purposes. Does the headset have a USB connection?

Was the EDID from direct DisplayPort connection or was the CAC-1335 involved? Can you get an EDID with the headset connected to the CAC-1335? It will be interesting to see how the CAC-1335 affects the EDID. I think it might try to add a HDMI 2.1 Vendor-Specific Data Block.

For both connection types (from HDMI and DisplayPort) can you open Device Manager, view by connection, find the headset, and see if it’s attached to Nvidia or Intel GPU?

The EDID has 2880×1440 90Hz mode (428MHz) which is doable by HDMI 2.0 (limit 600 MHz). Did you try this mode?

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The EDID has a 4320x2160 60Hz mode for HBR2 8bpc RGB/4:4:4 and a 90Hz mode for HBR3 8bpc RGB/4:4:4. There's no 4:2:2 or 4:2:0 or DSC support. Both of those modes are in the DisplayID 1.3 extension block. The CTA-861 extension block only contains a Microsoft Vendor-Specific Data Block which identifies the device as a Virtual reality headset and assigns a UUID which I suppose can be matched with a UUID of a corresponding USB device for position tracking purposes. Does the headset have a USB connection?
Was the EDID from direct DisplayPort connection or was the CAC-1335 involved? Can you get an EDID with the headset connected to the CAC-1335? It will be interesting to see how the CAC-1335 affects the EDID. I think it might try to add a HDMI 2.1 Vendor-Specific Data Block.
For both connection types (from HDMI and DisplayPort) can you open Device Manager, view by connection, find the headset, and see if it's attached to Nvidia or Intel GPU?
The EDID has 2880x1440 90Hz mode (428MHz) which is doable by HDMI 2.0 (limit 600 MHz). Did you try this mode?

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Jim

Joe,

Thanks for replying again. Let me try and answer you latest questions. The Virtual Reality Headset does have a USB connection to pass audio and to supply power to it from PC. I can only get a readiing from CRU when the VR Headset is connected to the mini-displayport on the older laptop. If I try to use the HDMI port and the CAC-1335 it is not recognized. It does not detect the video connection to the headset only the USB connection when I use the CAC-1335.

Both the HDMI and the Mini-DisplayPort connection on the laptop connect directly to the RTX3080 Graphics Card. I cannot try the 2880 X 1440 mode with the headset because it is not even recognized through the adapter. I can plug a 3440 X 1440 monitor into the direct HDMI slot or even connect it through the CAC-1335 with a DisplayPort Cable. But it doesn’t work on the VR Headset. What do we try next?

Thanks,

Jim

1 0 on 13-09-2022

joevt

Seems strange that the CAC-1335 works with other displays but not the headset. What kind of cable is between the headset and the CAC-1335? Can it be replaced? The cable should not include any other adapters if possible.

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Jim

Joe,

It is a cable that has a power adapter plugged into it with a switch, this adapter with the switch has a USB and a DisplayPort cable that goes to the VR Headset on one side and a DisplayPort coming into it on the other side. It is a very finnicky cable. HP came out with a revised version that had the switch about a year ago. I have that version. That very same cable does work perfectly when plugged into a DisplayPort to Mini-DisplayPort adapter and then the Mini-DisplayPort plugs into the laptop.

My motivation to get an HDMI 2.1 to DisplayPort connection is because my newer, more powerful laptop does not have a Mini-DisplayPort connected to the Discrete Graphic Card, only the HDMI port is connected to the Graphics Card. It has a Thunderbolt Port also, but that is connected to the Integrated Graphics.

I appreciate your continued help in trying to get this to work. I did try an HMDI repeater between the laptop and the CAC-1335. That made no difference. I have also ordered a DisplayPort 1.4 repeater to try between the CAC-1335 and the VR Headset. But I am thinking there is some configuration that we have not found right for the CAC-1335.

Thanks,

Jim

0 0 on 14-09-2022

joevt

I am thinking the CAC-1335 and CAC-1336 are more finicky then they should be. Read my post on the CAC-1336. CAC-1336 operation

The fact that you can’t use adapters with them is bad especially the CAC-1336 – not being able to use a USB-C to DisplayPort cable or adapter is just wrong for a USB-C port…

Maybe you would have more luck if you put a Thunderbolt 4 hub between a CAC-1336 and your displayPort cable/adapters. The Thunderbolt controller might act like a DisplayPort repeater. It’s an awfully expensive solution, if it even works.

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