I want to be able to play a video using the AppleTV app with the output going out the USB3/Thunderbolt port where I plugged in a HDMI adapter connected to my A/V receiver driving my TV. I do not have an AppleTV box. I'm using a MacBook Air M1 running the latest Big Sur.

I can "mirror" the display via the port/HDMI adapter to the receiver/TV, but this is not ideal as it lowers the resolution, requires me to use AirPlay to get the audio to the receiver, and I have to leave the laptop open, driving the internal display.


You need to open System Preferences, click Displays, select the Arrangement tab and then ensure "Mirror Displays" is unchecked.

In order to be able to close the laptop while keeping the external display output working, you will need to ensure the MacBook Air has the charger plugged in.

  • Attaching the MBA to the charger is the key step. It seems strange to me that the desktop background image is sent to the HDMI adapter, but only "active" content is sent once the laptop is closed. Plus, I would have thought closing the lid, and thus covering the speakers, would trigger sending audio, too, but I still have to change the speaker preference. Also the HDMI connection is finicky. I have to follow these steps in section 2 every time: support.apple.com/en-us/HT204388 Aug 4 at 13:01

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