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I have a Macbook Air 2017. My goal is to have an optical output capable of 5.1 audio for my home theatre. My series of connections are, mini display port to hdmi and the hdmi connected towards hdmi to optical output and optical connected to my 5.1 home theatre. My midi setup and audio out setting automatically detected the hdmi out and and the hdmi icon appeared in both settings. But in my midi setup, it is showing 8 channels but, volume level of all of them is shown as disabled.

All of the channel volume sliders are disabled.

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When I go for configuring, it shows 5.1 out. But when I tried to test each channels, only left and right are heard. All other channels are silent. When I played a 6 channel audio, it is missing every surround except from left & right.

I tried everything like soundflower, soundflowerbed app, MonitorControl etc. Nothing worked, still hearing only 2 channels.

Is there any solution for this? I need a 6 channel audio output.

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  • The audio being greyed out is normal; macOS doesn't provide a soft volume control like Windows does, and instead defers control to the HDMI device. This is expected. Can you provide some more details on your home theater setup? I experienced a similar issue when using ARC with a Sony receiver; however, it turned out to be (AFAIK) unrelated to the Mac and instead an issue with the calibration for the setup.
    – JMY1000
    Nov 24 '20 at 9:08
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According to Apple, the 2017 MacBook Air does not support audio over DisplayPort to HDMI devices. It is only supported on models from 2010 through 2015.

Send audio and video to HDMI displays through Mini DisplayPort

It explains what you are seeing/experiencing with the audio settings. It is detecting your HDMI device which is capable of 8.1 audio, but it simply cannot deliver it; thus all the settings are greyed out.

Now, when I have connected DisplayPort (or mDP) to a DisplayPort monitor with audio capabilities, they have always been stereo (left and right), never more than that. This corroborates what you’re experiencing - only left and right channels available. I currently don’t have an MBA to re-verify this, but this appears to be the case.

The 2018 MacBook Air (and on) with Thunderbolt 3 ports fully supports the HDMI 1.4b (minimum) spec with 8.1 audio.

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  • The date on this tech note is August 03, 2017 and clearly states: This article has been archived and is no longer updated by Apple. We have literally over 500 MBAs ranging from 2014, 2015, & 2017 models, all of which support audio out through HDMI. We've been using them in classrooms for years to connect to our projectors. Over time, we found that most 3rd party adapters are pure crap, both in performance, construction, or both, so perhaps the adapter is as fault. Our current MDP > HDMI is the Belkin 4K adapter (the rugged black model) and it just works.
    – IconDaemon
    Jun 9 '20 at 20:57
  • A comment on the first link (which is also linked to from the second page linked to): It was last updated 3rd August 2017, very shortly after the 2017 MBA was announced. And the 2017 MBA is not mentioned in neither the models capable of supplying sound over Mini DisplayPort nor in the models NOT capable. So it looks like the 2017 MBA was simply not included/available when this doc was last updated. I will also note the 2017 MBA is extremely similar in its internals as the 2015 model, insofar as their motherboards are completely interchangable. Jun 9 '20 at 21:05
  • No where did I say “audio” wasn’t supported. I said “Apple said it.” I said *personally” that I’ve had audio support but not 8.1. There’s a HUGE difference there. As far as release dates go, new MacBooks aren’t born spontaneously. They have and know the capabilities of prerelease devices up to a year in advance so saying it was “just released but not included/available” is nonsense.
    – Allan
    Jun 10 '20 at 3:28
  • So in general, I can't make 6 channel output from my macbook right? Is there any solution for it? Jul 16 '20 at 8:15
  • @soorejbabu - that sounds like a different question than what is posted here
    – Allan
    Jul 16 '20 at 16:10

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