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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:



Success on built in HDMI:



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

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Super User

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


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