fix(audio): keep built-in mic capture alive on Apple Silicon by Defake · Pull Request #912 · altic-dev/FluidVoice

Defake · 2026-08-28T14:48:23Z

Description

Direct Core Audio capture from the built-in microphone can become silent a few seconds after dictation starts on Apple Silicon, which truncates the transcription.

This change uses AVAudioEngine for the built-in microphone on Apple Silicon.

Type of Change

Related Issue or Discussion

Closes #852

Testing

Tested on Intel Mac
Tested on Apple Silicon Mac
Tested on macOS version: 26.6.2
Ran linter locally: swiftlint --strict --config .swiftlint.yml Sources
Ran formatter locally: swiftformat --config .swiftformat Sources
Ran tests locally: 334/335 passed on Apple Silicon; The Whisper Tiny E2E test failed because its Hugging Face model download timed out after three attempts (no access to internet during testing – was intended).

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No UI/visual changes; screenshots/video are not applicable.

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greptile-apps · 2026-08-28T14:51:55Z

Greptile Summary

The PR adds a silent built-in-output keep-alive while direct Core Audio captures from the internal microphone on Apple Silicon.

Selects the single live built-in output for eligible internal-microphone sessions.
Starts and synchronizes the output keep-alive before input capture, then tears both down together.
Adds output-liveness querying and policy-focused reliability tests.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains.

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chatgpt-codex-connector · 2026-08-28T15:45:34Z

+            isInternalMicrophone &&
+            selectedInputUID != nil &&
+            selectedInputUID == defaultInputUID


Keep non-default built-in microphones off direct capture

When the user prioritizes the built-in microphone in FluidVoice while macOS has an external input as its default, this equality makes the compatibility policy return false, so startConfiguredAudioCapture falls through to DirectCoreAudioLifecycleController for the built-in device. That is precisely the backend this change identifies as becoming silent after a few seconds on Apple Silicon, so dictation can still be truncated in this supported independent-routing configuration. The new UID-equality guard avoids the previously reported misrouting, but the fresh behavior is that it routes the selected built-in microphone back through the known-silent backend; the compatibility solution needs to preserve the selected endpoint rather than opting out.

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That's intended. Otherwise the app would ignore the selected user choice.

altic-dev · 2026-08-29T00:57:00Z

Hi, what is this PR supposed to do again? You have an issue?

Microphone is a very sensitive area and the issues that come up are very large. So I'd be very careful before merging this. But if you want to have a discussion on this, we are happy to take a look at it.

@grohith327 for viz

Defake · 2026-08-29T06:10:13Z

@altic-dev yes, FluidVoice is not usable for me since 1.6.7.

The issue I had created: #852

This PR fixes that built-in microphone stops capturing input after 3 seconds of dictation on Apple M1.

It switches built-in microphone capture to AVAudioEngine instead of using direct Core Audio. Only switches if both selected and default microphone are built-in and it's Apple Silicon.

altic-dev · 2026-08-29T06:13:40Z

@altic-dev yes, FluidVoice is not usable for me since 1.6.7.

The issue I had created: #852

This PR fixes that built-in microphone stops capturing input after 3 seconds of dictation on Apple M1.

It switches built-in microphone capture to AVAudioEngine instead of using direct Core Audio. Only switches if both selected and default microphone are built-in and it's Apple Silicon.

We're trying to move away from AvAudio and w e need to find a bette way for this. @grohith327 wdyt?

Not sure how to fix this in a bette way

grohith327 · 2026-08-30T01:20:28Z

@Defake The AVAudioEngine flow that exists right now will simply be removed in future commits as we have fully committed to the CoreAudio flow.

The equivalent fix for this in CoreAudio flow is there in this commit - 6fe6143

Can you try building this and let us know if it works. Thank you for trying really hard to get FV work!

Defake · 2026-08-30T05:22:56Z

@grohith327 thanks, I tried it 2 weeks ago, it didn't fix the issue: #852 (comment)

The problem is not zero-PCM. Capture starts normally and works for 3.5 seconds. Then corespeechd mutes the built-in microphone.

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chatgpt-codex-connector · 2026-08-30T09:28:32Z

+    status = fv_start_output_keep_alive(capture);
+    if (status != noErr) {
+        (void) fv_stop_and_destroy_output_keep_alive(capture);
+        return status;


Allow capture when the output keep-alive cannot start

When the built-in output is alive but cannot start this IOProc—for example, while held in exclusive/hog mode or when its first callback exceeds the fixed one-second timeout—this path aborts startup even though the selected microphone remains independently usable. startConfiguredAudioCapture propagates direct-capture failures, and the direct backend is mandatory, so after retrying or switching inputs the recording ultimately fails; treat a keep-alive failure as a degraded capture mode or fall back to another backend instead of making output availability a prerequisite for dictation.

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Defake · 2026-08-30T10:19:03Z

I reworked this PR so it works with Core Audio now.
On my Mac, direct Core Audio capture starts normally, but corespeechd mutes the built-in microphone after 3.5 seconds when no output stream is active. The PR now runs a silent Core Audio output callback on the built-in output while dictation is active.
@altic-dev @grohith327 please take a look.

Defake added 2 commits August 28, 2026 20:21

fix(audio): keep built-in mic capture alive on Apple Silicon

1526396

style(audio): satisfy SwiftLint

b79d729

chatgpt-codex-connector Bot reviewed Aug 28, 2026

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Comment thread Sources/Fluid/Services/ASRService.swift Outdated

greptile-apps Bot reviewed Aug 28, 2026

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Defake marked this pull request as draft August 28, 2026 15:28

fix(audio): preserve selected microphone routing

02aa444

Defake marked this pull request as ready for review August 28, 2026 15:42

greptile-apps Bot reviewed Aug 28, 2026

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Defake mentioned this pull request Aug 28, 2026

[BUG] Dictation stops detecting microphone input after 3 seconds #852

Open

revert: remove AVAudioEngine built-in mic workaround

b3f54a1

fix(audio): keep built-in output active during capture

95b08c3

chatgpt-codex-connector Bot reviewed Aug 30, 2026

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Defake commented Aug 28, 2026

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altic-dev commented Aug 29, 2026

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