No sound through HDMI with Mac Mini Connected to Projection TV

Solution 1:

I talked with the company that sold me most of my system (but not the Mac - just everything else) and we couldn't find a solution. I called Metra, the people who make the HDMI switch and one of them suggested something I could get from Amazon. It cost me $22.49 and fixed it.

I don't want to advocate for a particular brand, but what I found seems to not have a clear name yet. Some are listed as HDMI feeders (the one I got that works is listed as an "HDMI feeader" [sic], which makes it easy to find. Some are called HDMI EDID Emulators. If you want to see examples, search for HDMI EDID changer (or emulator or anything close to that).

This is a small device that runs off the power from the HDMI cable. Mine has a small post sticking out that looks like the post on a typical potentiometer. There are 16 different positions and a chart on the back. I picked "4k 5.1CH." (The Sony projector is 4K, so the only thing that changed was the audio - which is, as I indicated, non-existent on the Sony projector.)

When I put the feeder in, between the Mac and the Metra HDMI switcher, the screen went blank for about 10-20 seconds, then the Mac display came back up. Same when I changed the box to the setting I wanted. It went blank for about 10 seconds, then the display returned.

I had a video playing on the Mac. After the display came back on, with 2-3 seconds, the sound changed from being played on the Mac speakers to coming from my Sonos system. (It may have changed with the display - I can't remember.)

So it's working okay. The solution was the HDMI EDID emulator that edits the EDID from the projector to add the audio specs to it.

Solution 2:

I'm wondering if there's a way to override and tell sound, "Just send through the HDMI output."

No. You can’t do this because this is not the way it works. You’re treating this as if it were an analog audio signal that you’re just going put on the wire and it’s just going to be there.

HDMI is a digital signal which encapsulates both audio (compressed and uncompressed) as well as a video signal. Basically, the audio has to be encoded and decoded and to do so, it requires two way communication between the source (Mac mini) and the end device. Since your Metra ethereal device doesn’t have this capability, your Mac doesn’t "see" it as an audio device which means no audio signal will be sent. In other words, there's nothing telling your Mac "hey, I'm an audio device."

HDMI Pin Outs

Notice that there are no audio pins; there's basically, data, grounding, clock sync, the Consumer Electronics Control (CEC), shielding and some +5V power. If you wanted to extract audio, you'd have to pull it out of the data being sent.

You need an HDMI endpoint device

To be clear, the issue is your Metra device. It’s not your projector or your Sonus. The Metra must present itself as an audio device (or at least properly pass the HDMI signal through to another HDMI device). We know it to be a problem because you experienced the same issue with the Sony BD player...

It's worth noting that I had a similar problem with the [Sony] BD Player.

To solve this, you will most likely need a proper HDMI Audio extractor that will not only provide switching capabilities, but will appear as a bona fide audio device to the Mac and/or pass the proper EDID data through to the Mac.