How do I check the active audio codec for a bluetooth connection in Big Sur?

Question

How do I check the active audio codec for a bluetooth connection in Bug Sur?

In Catalina, you used to be able to option-click on the Bluetooth item in the menubar, and then it would show more detail about every item including the codecs for audio devices. Now it still shows the additional detail but not the audio codec.

How do I see the audio codec being used now -- for instance, to ensure that my headphones are using AAC and not SBC?

Answer 1

Download Bluetooth Explorer, open it, then navigate to Tools > Audio Graphs. You can see at the bottom the active codec - in this example I'm using AAC.

Note that Bluetooth Explorer is no longer included in the latest Xcode Additional Tools bundle. The last version I could find was for Xcode 11, and it now crashes sometimes on Big Sur, but still does the trick. Download it here: https://developer.apple.com/download/more/?=additional%20tools

Answer 2

Pasting a solution I found from a GitHub gist comment. This works from me on Monterey.

1. Disconnect your headphones.
2. Open the "Console" app (Under "Applications/Utilities").
3. In the "Search" field, in the upper-right corner, type "Codec", and hit "Enter".
4. Hit the "Start" button.
5. Re-connect your headphones while looking at the Console output.
6. After a few seconds, you should see a bunch of lines appear, including one starting with "A2DP", like this:

00:48:15.750396-0400 bluetoothd A2DP configured at 44.1 KHz. Codec: AAC-LC, VBR max: 256 kbps. 1 frames * (12+744) bytes = 756 per RTP (max=879) every 23.22 ms