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The promo for Airpods 3 claim to use the AAC-ELD codec for better two-way audio quality with FaceTime. Before I purchase Airpods 3, I'd like to be sure this claim is actually true:

Do Airpods 3 use AAC-ELD on macOS with FaceTime and other audio chat applications?

Thanks for shedding some light on the matter!

Someone who already owns Airpods 3 could figure it out roughly as follows:

On macOS, when the Airpods are connected and sending/receiving, you can see the currently used codec by holding the alt-key and clicking on the Bluetooth menu bar item.

So after pairing the Airpods 3 e.g. with a MacBook, in the audio preferences, set both input and output to use the Airpods. Then open some audio chat app such as Slack, start a conversation and check which codec is in use. (If it sounds like an 80s landline connection, you should most likely see SCO as codec in use.)

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  • You’ve got several question in the middle. Could you perhaps rephrase this so there are assumptions listed and then one specific question at the end with an edit?
    – bmike ♦
    Commented Nov 7, 2021 at 17:56
  • Not sure whether it's much clearer now, but I've rephrased the question.
    – svoop
    Commented Nov 9, 2021 at 18:20
  • Thanks. I’ll vote it up. Good edits!
    – bmike ♦
    Commented Nov 10, 2021 at 4:41

2 Answers 2

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The ALT+Bluetooth menu was removed in MacOS Monterey, which is also the first version to support AirPods 3, so there is now way to check it anymore. Even their Bluetooth Explorer Developer Tool either does not work anymore or does not tell you that specific detail.

However, the Console app (not the Terminal) does log what codec is negotiated. And there you see, even my AirPods Pro's now use AAC-ELD at 24000 Hz. Log messages

The sample rate of 24000 Hz is still not what I would call "HD", but better than the 16000 Hz of the previous mSBC profile. If you want to know more, then I recommend ValdikSS excellent article about bluetooth audio.

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    Thanks for your investigation! Meanwhile, I've updated to Monterey and poked around a little. You might be able to find out more like this: Open the Console, select your device and click on "start streaming". Now connect the Airpods. As messages are flowing in, use the search input above to filter for keywords such as "codec".
    – svoop
    Commented Dec 16, 2021 at 18:46
  • @svoop I didn't know that there is such a log explorer. I tried it and I actually got the line "Setting SCO audio codec to AAC-ELD at sample rate of 24000 for device <private>". So this is more or less a confirmation.
    – Nemo64
    Commented Dec 17, 2021 at 19:37
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    I updated the answer so that anyone searching does not have to read though my investigation and can just get the answer.
    – Nemo64
    Commented Dec 17, 2021 at 19:48
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Nemo64 I just wanted to add a bit of context to your answer, but I'm am not allowed to comment yet.

The sample rate of 24000 Hz is still not what I would call "HD"

AAC-ELD uses Spectral Band Replication (SBR) similar to HE-AAC. HE-AAC encodes one main audio stream and a secondary SBR stream. The main stream is encoded using plain AAC at a reduced sample rate. Typically half. An additional SBR stream encodes the remaining bandwidth by differencing with the main audio stream (à la MP3's Joint Stereo). When you see a HE-AAC or AAC-ELD stream reporting 24000Hz, the codec is reporting the sample rate of the base stream. SBR is a second decode pass that is able to "unfold" the higher frequency portion of the audio. This is also backwards-compatible, since a normal AAC decoder will only "see" the main stream and play it at half bandwidth. A compliant HE-AAC or AAC-ELD decoder will be able to decode the full bandwidth.

tl;dr AAC-ELD reports half of the bandwidth encoded. 24000hz here actually means 48000Hz.

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  • 1
    You can edit existing answers to add details.
    – nohillside ♦
    Commented Dec 30, 2021 at 11:27
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    I don't think a comment or an edit is appropriate here. This bit of context is longer than the answer itself.
    – muskwasis
    Commented Dec 30, 2021 at 20:00
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    Good catch. Although SBR isn't perfect and there is a noticeable quality difference in going from the normal AAC profile to the AAC-ELD profile, so the "not HD" observation is still valid. The 64 kbit/s limit in bluetooths hands free profile probably doesn't help either.
    – Nemo64
    Commented Jan 21, 2022 at 11:10
  • Yeah it sucks more than it should. I think I would be better off with LC3 and pipewire instead. Does your set stutter in AAC-ELD mode? To test go to Perf > Sound > Input. They will stay in AAC-ELD while this window is open. Then listen to some music or watch a movie.
    – muskwasis
    Commented Jan 26, 2022 at 3:10

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