feat: add AudioRecorder (16 kHz mono) and record probe

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
2026-10-01 09:46:15 +02:00
parent 1c581e8eae
commit 28515d9c87
3 changed files with 94 additions and 1 deletions
@@ -0,0 +1,67 @@
+import AVFoundation
+
+public final class AudioRecorder: AudioRecording {
+    public enum RecorderError: Error, LocalizedError {
+        case converterUnavailable
+
+        public var errorDescription: String? {
+            "Kon de microfoon niet omzetten naar 16 kHz mono."
+        }
+    }
+
+    private let engine = AVAudioEngine()
+    private let lock = NSLock()
+    private var buffer: [Float] = []
+    private let targetFormat = AVAudioFormat(
+        commonFormat: .pcmFormatFloat32,
+        sampleRate: 16_000,
+        channels: 1,
+        interleaved: false
+    )!
+
+    public init() {}
+
+    public func start() throws {
+        lock.withLock { buffer.removeAll(keepingCapacity: true) }
+
+        let input = engine.inputNode
+        let inputFormat = input.outputFormat(forBus: 0)
+        guard let converter = AVAudioConverter(from: inputFormat, to: targetFormat) else {
+            throw RecorderError.converterUnavailable
+        }
+        let ratio = targetFormat.sampleRate / inputFormat.sampleRate
+
+        input.installTap(onBus: 0, bufferSize: 4096, format: inputFormat) { [weak self] pcm, _ in
+            guard let self else { return }
+            let capacity = AVAudioFrameCount(Double(pcm.frameLength) * ratio) + 1
+            guard let out = AVAudioPCMBuffer(pcmFormat: self.targetFormat, frameCapacity: capacity) else { return }
+
+            var consumed = false
+            var error: NSError?
+            converter.convert(to: out, error: &error) { _, status in
+                if consumed {
+                    status.pointee = .noDataNow
+                    return nil
+                }
+                consumed = true
+                status.pointee = .haveData
+                return pcm
+            }
+            guard error == nil, let channel = out.floatChannelData?[0] else { return }
+            let samples = Array(UnsafeBufferPointer(start: channel, count: Int(out.frameLength)))
+            self.lock.withLock { self.buffer.append(contentsOf: samples) }
+        }
+        engine.prepare()
+        try engine.start()
+    }
+
+    public func stop() -> [Float] {
+        engine.inputNode.removeTap(onBus: 0)
+        engine.stop()
+        return lock.withLock {
+            let samples = buffer
+            buffer = []
+            return samples
+        }
+    }
+}