Big Sur Audio keeps switching to HDP codec from AADP when input and output is being used at same time [duplicate]
Ever since I purchased the AirPods (1st Generation), they demonstrate extremely poor quality while activating the AirPod mic, whilst they are connected to a Mac. When activating the mic to record audio, it seems that both the recording quality AND audio playback quality severely drops to a substandard level (Mono 8.0 kHz).
For example, if I invoke Siri on the Mac, whatever is being said and recorded by me, AND the Siri/Mac/AirPod audio response will be in poor quality. After the recording is done, audio playback quality usually goes back to normal1. Any mic audio recorded to a file will however be in the poor quality; which is why I interpret the issue to affect both recording and playback qualities.
The issue appears to be identical to the one discussed in this Apple Support Forum thread. The thread offers possible explanations but no definitive solution or suggested course of action.
I have this issue with several Macs of various recent models. I don't have this problem when using the AirPods with an iPhone. I have tried resetting the Mac Bluetooth interface, tried resetting the AirPods, and so forth.
FYI: Using the macOS native application Audio MIDI Setup, I attempted to observe what's happening when AirPod recording is activated. Output quality drops from the standard 2 ch 24-bit Integer 44.1 kHz → 1 ch 16-bit Integer 8.0 kHz.
1It has happened that the Mac got permanently stuck in low quality until system reboot, or even whenever the AirPods were connected afterwards. I had to attempt AirPod unpair/re-pair, and even a charging case reset to fix the latter situation.
OP here – I'd just like to add to the answer below, that I've been in contact with Apple Support.
Explanation
Apple claims that the poor Mono 8kHz quality which affects recording and indeed simultaneously playback on Mac when the AirPod microphones are activated, is because the SCO codec then gets employed over the entire Mac audio system. This is supposedly "expected behaviour" when trying to use the AirPods and other Bluetooth headsets together with a computer, according to Apple.
The AAC codec is normally used when just listening to playback on the AirPods. It's just very unfortunate that SCO – low-quality as it may be – upon AirPod microphone activation is not only limited to doing recording, but also displaces AAC and audio playback.
Apple Support claims that Apple is looking at this issue, and that improvements might be coming in future firmware updates, but I did not interpret that as a promise to be honest. But for the time being, I'd say that the benefits of making calls and so forth with AirPods on Macs are quite limited.
Current best practice
Current best practice is to use the Internal Microphone for Recording, and the AirPods for playback when conducting calls. Input and Output devices can be selected in System Settings > Sound or by ⌥-clicking the Volume icon in the macOS Menu Bar, and selecting devices there.
See the screenshots below:
I found this on the Apple Discussion boards:
... they are aware of the issues and a temporary workaround is to switch the mic from the AirPods mic to the internal microphone.
On the discussion post you referenced, there was 217 other people reporting that they too had this issue.
Also from a May 6th Apple Tool Box article:
Many of our readers are letting us know that their AirPods are experiencing a lot of challenges while using them with macOS. In particular, when the mic is used, the AirPods’ audio is very low fidelity and sound quality. Some iFolks claim that they cannot even understand the other person when video-chatting with apps like FaceTime, Hangouts, and Skype. And your callers also report that your voice sounds muddy or that they barely hear you at all.
Is there a fix?
Other than the workaround to use your internal mic, no. My advice is to return the unit to Apple. There may be a fix in a future update to macOS or the AirPod firmware, but only Apple knows when they will issue an update. Given that Apple "silently" released the last update, don't expect too much fanfare with the next one.
Personally, I would have returned them and/or opened a support case with Apple as they are the best ones to solve this issue.
This is not an issue with your "bluetooth chip" as per the comments. This would be easy to diagnose - test you MBP with other BT headsets. If the problem goes away, it's the AirPods.
As the answer already states, it's because the AirPods change to the SCO codec. The bad news is, there is no way to permanently change this in macOS High Sierra¹ - there was a way to fix it in macOS Sierra, so if anyone reads this and hasn't yet updated, try this:
Use Apple's developer tool Bluetooth Explorer. Then you can use Audio Options (under Tools in the menu bar) to force them to use the alternative codec aptX.
- Official download, if you're a member of Apple Developer:
https://developer.apple.com/download/more/ (search for Additional Tools)
That's also where it states that it requires macOS Sierra. - Inofficial download, plus description with screenshots:
http://www.theghostbit.com/2015/03/force-mac-os-x-to-use-aptx-with-your.html
Full disclosure: Unfortunately I can't try it myself. (This is the first time I regret updating to the newest Apple OS...)
¹ the temporary workaround from the other answer works, obviously, you just have to do it every time.