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M3: Update AlwaysOnAudioMonitor for 16kHz mono format #8318

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Merged
alex-nork merged 1 commit into from
Feb 24, 2026
Merged

M3: Update AlwaysOnAudioMonitor for 16kHz mono format #8318

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15 changes: 11 additions & 4 deletions clients/macos/vellum-assistant/Features/Voice/WakeWord/AlwaysOnAudioMonitor.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -96,13 +96,20 @@ final class AlwaysOnAudioMonitor: ObservableObject {
throw AudioMonitorError.noInputChannels
}

// Install a tap using the hardware format for low-latency capture.
// The buffer is available for the WakeWordEngine to consume via its
// own internal processing (the engine's start() primes it for detection).
// Porcupine requires 16kHz mono Int16 PCM. Request 16kHz mono Float32 from
// AVAudioEngine (which handles resampling internally); the tap callback
// converts Float32 → Int16 before feeding the wake word engine.
let targetFormat = AVAudioFormat(
commonFormat: .pcmFormatFloat32,
sampleRate: 16000,
channels: 1,
interleaved: false
)!

inputNode.installTap(
onBus: 0,
bufferSize: Self.bufferSize,
format: hwFormat
format: targetFormat
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) { [weak self] buffer, _ in
guard let self else { return }
guard let floatData = buffer.floatChannelData else { return }
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