Community
cancel
Showing results for 
Search instead for 
Did you mean: 
JSwen1
Beginner
145 Views

DDC/CI Communication Issue over HDMI

I'm having an issue communicating with a display connected over HDMI. I'm on a Macmini8,1 using an Intel iGPU. I'm attempting to use the Windows low-level monitor configuration APIs to list VCP commands. I wrote a quick example program here.

 

When I run my program on the built in HDMI port, the `GetCapabilitiesStringLength` function fails with a somewhat generic error (shown below). However, when I plug in a USBC->HDMI adapter the API responds the way I expect it to (also shown below).

 

I've tried upgrading to the latest driver, downgrading to the oldest driver I can find, completely removing the Intel driver, and a different display entirely. I'm following the steps outlined by Microsoft to list VCP commands. I've also successfully run this program on a PC with a discrete nVidia GPU without issue. I think the issue is with the Intel driver itself.

 

Failure on built in HDMI:

macmini8,1-hdmi.png

 

Success on built in HDMI:

macmini8,1-usbc-hub-with-hdmi.png

 

Depending on the existence of an adapter isn't something that is acceptable for my application. Is there anything else I can try?

0 Kudos
1 Reply
n_scott_pearson
Super User Retired Employee
114 Views

Sorry, Apple has requested that all issues involving their hardware be redirected to their support center.

...S

Reply