Why Is ScreenCaptureKit Ignoring the Built-In Microphone on macOS 15+?

Below is a summary of the current state and some suggestions based on the developer documentation and known community experiences:

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What’s Happening

Although ScreenCaptureKit provides a flag (captureMicrophone) and even lets you supply a device ID (or use nil for the default built‑in microphone), many developers have found that—even when all required privacy settings (Info.plist keys and Audio Input Resource Access) are in place—the microphone input isn’t delivered, whereas video capture (and even system audio capture) works as expected.

Apple’s own sample app (and documentation such as “Capturing screen content in macOS”) similarly does not demonstrate microphone capture functionality. This seems to be a limitation (or current bug) in macOS 15+ rather than an issue in your code.

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Suggestions & Workarounds

1. Double‑Check App Permissions:
   Although you mentioned that both Info.plist privacy settings and Resource Access have been set, try temporarily logging the authorization status for microphone access or re‑triggering the permission prompt to ensure no issues here.

2. Avoid Stream Output Conflicts:
   Although adding multiple stream outputs (for .screen, .audio, and .microphone) is expected, try testing with only the microphone output to verify that nothing about the combined configuration causes conflicts. For example, comment out the .audio output and confirm if any microphone samples arrive:

   SWIFTCopied
   do {
       try stream.addStreamOutput(streamOutput, type: .screen, sampleHandlerQueue: videoSamplesQueue)
       // Uncomment only the microphone output below for testing
       try stream.addStreamOutput(streamOutput, type: .microphone, sampleHandlerQueue: microphoneSamplesQueue)
       
       stream.startCapture()
       logger.info("Started capturing...")
   } catch {
       logger.error("Unable to start capturing.")
   }

3. Monitor Developer Forums and Updates:
   Several developers (including those on StackOverflow) have reported similar issues, and Apple may address this in a future update. Keep an eye on Apple Developer Forums and WWDC sessions for any announcement regarding microphone capture with ScreenCaptureKit.

4. Alternate Approaches:
   When system‑provided microphone capture via ScreenCaptureKit isn’t working, some have investigated alternatives such as using lower‑level Core Audio APIs. Unfortunately, many AVAudio* APIs for capturing mic input are designed for iOS and don’t offer a seamless solution on macOS. The lack of a built‑in alternative in macOS leaves you with fewer options until this limitation is resolved at the framework level.

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Conclusion

Your sample code appears to follow the recommended approach—setting captureMicrophone to true and (by passing nil) opting for the built‑in device—but this is a known issue with ScreenCaptureKit on macOS (15+), not a mistake in your app’s configuration. At the moment, if you need microphone capture, the only workarounds are to simplify your configuration to isolate microphone input or wait for Apple’s next update to address the problem.

If you continue to encounter problems, consider filing a bug report with Apple so they can further investigate this behavior.

Remember to monitor Apple’s documentation updates and developer forums for any news regarding improvements or fixes in future macOS versions.