2018 Mac mini thinks HDMI is DisplayPort - no 5.1 sound

[house13um]

This is a strange one, to me at least.

I have a 2018 Mac mini connected via HDMI to a Yamaha RX-V385, which is connected to an Acer XF270HUA. This was the arrangement I had when I bought the Mac and set it up for the first time; didn't have any issues and it recognized 5.1 surround sound, which worked perfectly.

Fast forward to yesterday, I turn the Mac off, disconnect the HDMI, connect the Mac straight up to the Acer monitor via DisplayPort in order to test out a USB-C to DisplayPort cord I recently got, and turned it back on. That worked fine. Once done, I turned it back off and switched back to HDMI. Now, the Mac doesn't recognize the 5.1 surround sound, and it lists the audio output device as DisplayPort in the sound settings.

Clearly I have confused my little Mac. What do I need to do?

 

[joevt]

This is a strange one, to me at least.

I have a 2018 Mac mini connected via HDMI to a Yamaha RX-V385, which is connected to an Acer XF270HUA. This was the arrangement I had when I bought the Mac and set it up for the first time; didn't have any issues and it recognized 5.1 surround sound, which worked perfectly.

Fast forward to yesterday, I turn the Mac off, disconnect the HDMI, connect the Mac straight up to the Acer monitor via DisplayPort in order to test out a USB-C to DisplayPort cord I recently got, and turned it back on. That worked fine. Once done, I turned it back off and switched back to HDMI. Now, the Mac doesn't recognize the 5.1 surround sound, and it lists the audio output device as DisplayPort in the sound settings.

Clearly I have confused my little Mac. What do I need to do?

The Mac mini 2018 can do digital audio to DisplayPort or HDMI.

The Mac mini 2018 reports the audio output device of a HDMI connected display as DisplayPort because the Mac mini 2018 uses a built-in DisplayPort to HDMI 2.0 adapter. That's because DisplayPort Dual Mode (DP++) (which would be direct HDMI from the iGPU) only supports HDMI 1.4.

I noticed recently that my DisplayPort connected display stopped appearing as a audio output device. I use SwitchResX to add custom resolutions. It's possible SwitchResX may have overridden the EDID in such a way that caused macOS to think the display does not have audio so I clicked the "Restore factory settings" button, then clicked "Activate immediately". Then the audio device appeared again.

 

[joevt]

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