CarPlay: Is vehicle microphone capture without entering communications audio mode supported for third-party apps?

App & System Services CarPlay
Hearsave OP
Created 2w
Replies 7
Boosts 0
Views 622
Participants 2

Hello,

I am developing a native CarPlay application and would appreciate some clarification regarding AVAudioSession behaviour when using the vehicle microphone.

The application is intentionally simple and designed to minimise driver distraction.

The user presses a single button on the CarPlay screen, the application performs a brief (approximately five second) audio capture, performs application-specific processing on the captured audio, displays a simple confirmation to the user, and immediately releases the audio session.

The goal is to allow the driver to continue their journey with as little interaction as possible.

Because the audio being captured is often originating from the vehicle’s native DAB/FM radio rather than from the iPhone itself, preserving the existing listening experience during the brief capture is fundamental to the intended design.

To better understand what is supported by CarPlay, I have carried out a number of controlled experiments.

Test Environment

  • Native CarPlay application
  • Swift
  • AVFoundation
  • AVAudioSession
  • AVAudioRecorder
  • Vehicle connected via CarPlay
  • Vehicle playing its native DAB radio

Experiment 1

Configuration

Category: AVAudioSession.Category.playAndRecord

Mode: AVAudioSession.Mode.default

Observed Route

Input: CarPlay — CarAudio

Output: CarPlay — CarAudio

Result

  • Recording succeeds using the vehicle microphone.
  • Native DAB audio is muted during recording.
  • The vehicle changes from “Audio Volume” to “Voice Volume”.
  • When recording finishes and the AVAudioSession is deactivated, DAB resumes normally.

Experiment 2

Changed only the session mode to:

AVAudioSession.Mode.measurement

Result

Behaviour was identical to Experiment 1.

Experiment 3

Changed only the session mode to:

AVAudioSession.Mode.videoRecording

Observed Route

Input: iPhone microphone

Output: CarPlay — CarAudio

Result

  • Input automatically switched from the vehicle microphone to the iPhone microphone.
  • The vehicle remained in normal “Audio Volume”.
  • However, the head unit switched away from its native DAB source to the CarPlay media source.

Observation

These experiments appear to suggest that the behaviour is specifically related to using the CarPlay “CarAudio” microphone route, rather than audio recording itself.

Question

Is this the expected behaviour for third-party CarPlay applications?

More specifically:

Is there any supported AVAudioSession configuration or CarPlay API that allows a third-party CarPlay application to perform a brief, user-initiated audio capture using the vehicle microphone without causing the head unit to enter its communications/voice audio mode or interrupt the vehicle’s native radio playback?

If this behaviour is by design and no supported mechanism exists to achieve this, confirmation of that would be extremely valuable, as it would allow us to design the application accordingly.

If additional information, sample code, AVAudioSession logs or detailed reproduction steps would be helpful, I would be more than happy to provide them.

Thank you very much for your time.

Kind regards,

Neil Jenner Developer, HearSave

Replies  7
Boosts  0
Views  622
Participants  2
DTS Engineer OP
Apple
2w

Thanks for the post, extremely interesting.

There is no supported AVAudioSession configuration or CarPlay API that allows a third-party application to capture audio using the vehicle’s microphone without interrupting audio and also should be against the privacy concerns. When your app activates an AVAudioSession that requires the vehicle's microphone must switch its active audio context to Speech. When the Head Unit switches to a Speech/Telephony context to activate the microphone, that native media sources must be muted or paused.

Take a look at AVAudioSession https://developer.apple.com/documentation/avfaudio/avaudiosession

and

https://developer.apple.com/documentation/avfaudio/handling-audio-interruptions

Looking forward to CarPlay team to jump into the thread as if seems like your workflow is not supported at this time. However other engineers can confirmed that.

Albert  WWDR
Hearsave OP
2w

Thank you very much for the detailed response and for taking the time to explain the current behaviour.

That aligns closely with the results of my own experiments, where requesting the CarPlay vehicle microphone consistently causes the head unit to switch to its speech audio context (Voice Volume) and interrupt native DAB playback.

I appreciate your clarification that there is currently no supported AVAudioSession configuration to avoid this.

As you mentioned, I would also be very interested to hear from the CarPlay team whether this behaviour is an intentional platform limitation, or whether there are any supported approaches for applications with this workflow.

If additional information, AVAudioSession logs or a small reproducible sample project would be useful, I would be happy to provide them.

many thanks Neil

DTS Engineer OP
Apple
2w

Neil,

It think the best approach is to file an enhancement request for that team to provide you that capabilities you are looking for.

If you'd like us to consider adding the necessary functionality, please file an enhancement request using Feedback Assistant. Once you file the request, please post the FB number here.

If you're not familiar with how to file enhancement requests, take a look at Bug Reporting: How and Why?

Albert  WWDR
Hearsave OP
2w

Hi Albert,

Thank you again for your guidance throughout this discussion.

As suggested, I have now submitted an enhancement request.

Feedback ID: FB24019676

I appreciate you taking the time to review the original question and point me in the right direction.

Kind regards, Neil

DTS Engineer OP
Apple
2w

Thank you so much for the number, looks like already got routed to the correct team. Let's give them sometime to look at it and they'll contact you on the Feedback Assistant app.

You can see the status of your feedback in Feedback Assistant. There, you can track if the report is still being investigated, has a potential identifiable fix, or has been resolved in another way. The status appears beside the label "Resolution." We're unable to share any updates on specific reports on the forums.

For more details on when you'll see updates to your report, please see What to expect after submission.

Albert  WWDR
Hearsave OP
2w

Hi Albert,

Thank you again for all your help and guidance throughout this discussion. I really appreciate you taking the time to review the question and point me in the right direction.

Kind regards,

Neil

DTS Engineer OP
Apple
2w

@Hearsave Very happy to help. I'll keep an eye out on that bug and hope for a quick resolution.

Thanks again

Albert  WWDR

CarPlay: Is vehicle microphone capture without entering communications audio mode supported for third-party apps?
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