no need for buffer overflow error

Wait for aggregate device ID to be valid

Sources/CLI/AudioTee.swift

@@ -200,7 +200,7 @@ struct AudioTee {
 // Helper for stderr output
 var standardError = FileHandle.standardError
 
-extension FileHandle: @retroactive TextOutputStream {
+extension FileHandle: TextOutputStream {
   public func write(_ string: String) {
     let data = Data(string.utf8)
     self.write(data)

Sources/Core/AudioBuffer.swift

@@ -2,17 +2,62 @@ import CoreAudio
 import Foundation
 
 public class AudioBuffer {
-  private var buffer = Data()
-  private let targetChunkDuration: Double
-  private let streamFormat: AudioStreamBasicDescription
+  private var buffer: [UInt8]
+  private var writeIndex: Int = 0
+  private var readIndex: Int = 0
+  private var availableBytes: Int = 0
+  private let maxBufferSize: Int
+  
+  private let bytesPerChunk: Int
+  private let chunkDuration: Double
 
   public init(format: AudioStreamBasicDescription, chunkDuration: Double = 0.2) {
-    self.streamFormat = format
-    self.targetChunkDuration = chunkDuration
+    
+    // Pre-calculate chunk parameters
+    let bytesPerFrame = Int(format.mBytesPerFrame)
+    let samplesPerChunk = Int(format.mSampleRate * chunkDuration)
+    self.bytesPerChunk = samplesPerChunk * bytesPerFrame
+    self.chunkDuration = Double(samplesPerChunk) / format.mSampleRate
+
+    // Calculate max buffer size to hold ~10 seconds of audio, way more than the maximum we allow
+    let bytesPerSecond = Int(format.mSampleRate) * bytesPerFrame
+    self.maxBufferSize = bytesPerSecond * 10
+    
+    // Pre-allocated ring buffer
+    self.buffer = Array(repeating: 0, count: maxBufferSize)
   }
 
   public func append(_ data: Data) {
-    buffer.append(data)
+    guard availableBytes + data.count <= maxBufferSize else {
+      Logger.error("Audio buffer overflow", context: [
+        "requested": String(data.count),
+        "available": String(maxBufferSize - availableBytes)
+      ])
+      return
+    }
+    
+    data.withUnsafeBytes { bytes in
+      let sourceBytes = bytes.bindMemory(to: UInt8.self)
+      let dataSize = sourceBytes.count
+      
+      // Check if we can copy in one block (no wrap-around)
+      if writeIndex + dataSize <= maxBufferSize {
+        // only one write needed
+        buffer.replaceSubrange(writeIndex..<writeIndex + dataSize, with: sourceBytes)
+        writeIndex = (writeIndex + dataSize) % maxBufferSize
+      } else {
+        // two writes needed due to wrap-around
+        let firstChunkSize = maxBufferSize - writeIndex
+        let secondChunkSize = dataSize - firstChunkSize
+        
+        buffer.replaceSubrange(writeIndex..<maxBufferSize, with: sourceBytes.prefix(firstChunkSize))
+        buffer.replaceSubrange(0..<secondChunkSize, with: sourceBytes.suffix(secondChunkSize))
+        
+        writeIndex = secondChunkSize
+      }
+    }
+    
+    availableBytes += data.count
   }
 
   public func processChunks() -> [AudioPacket] {
@@ -25,37 +70,37 @@ public class AudioBuffer {
     return packets
   }
 
-  public func flushRemaining() -> AudioPacket? {
-    guard !buffer.isEmpty else { return nil }
+  private func nextChunk() -> AudioPacket? {
+    // Check if we have enough data for a complete chunk
+    guard availableBytes >= bytesPerChunk else { return nil }
 
-    let packet = AudioPacket(
-      timestamp: Date(),
-      duration: 0.0,  // Unknown duration for final chunk
-      peakAmplitude: 0.0,
-      rawAudioData: buffer
-    )
+    var chunkData = Data(capacity: bytesPerChunk)
     
-    buffer.removeAll()
-    return packet
+    // Check if we can copy in one block (no wrap-around)
+    if readIndex + bytesPerChunk <= maxBufferSize {
+      // one copy needed
+      chunkData.append(contentsOf: buffer[readIndex..<readIndex + bytesPerChunk])
+      readIndex = (readIndex + bytesPerChunk) % maxBufferSize
+    } else {
+      // two copies needed due to wrap-around
+      let firstChunkSize = maxBufferSize - readIndex
+      let secondChunkSize = bytesPerChunk - firstChunkSize
+      
+      chunkData.append(contentsOf: buffer[readIndex..<maxBufferSize])
+      chunkData.append(contentsOf: buffer[0..<secondChunkSize])
+      
+      readIndex = secondChunkSize
     }
     
-  private func nextChunk() -> AudioPacket? {
-    let bytesPerFrame = Int(streamFormat.mBytesPerFrame)
-    let samplesPerChunk = Int(streamFormat.mSampleRate * targetChunkDuration)
-    let bytesPerChunk = samplesPerChunk * bytesPerFrame
-
-    guard buffer.count >= bytesPerChunk else { return nil }
-
-    let chunkData = buffer.prefix(bytesPerChunk)
+    availableBytes -= bytesPerChunk
 
     let packet = AudioPacket(
       timestamp: Date(),
-      duration: Double(samplesPerChunk) / streamFormat.mSampleRate,
-      peakAmplitude: 0.0,  // No analysis in raw mode
-      rawAudioData: Data(chunkData)
+      duration: chunkDuration,
+      peakAmplitude: 0.0,
+      rawAudioData: chunkData
     )
 
-    buffer.removeFirst(bytesPerChunk)
     return packet
   }
 }

Sources/Core/AudioRecorder.swift

@@ -74,7 +74,8 @@ public class AudioRecorder {
     Logger.info("Audio device started successfully")
   }
 
-  // FIXME: note to self, what about installTap? Would require audio engine and a node?
+  // Note to self, what about installTap? Would require audio engine and a node?
+  // No; AudioEngine.installTap() can only fire as often as 100ms. too slow for us
   private func setupAndStartIOProc() {
     Logger.debug("Creating IO proc")
     var status = AudioDeviceCreateIOProcID(
@@ -126,8 +127,8 @@ public class AudioRecorder {
 
   func stopRecording() {
     // Send any remaining buffered audio, applying conversion if needed
-    if let finalPacket = audioBuffer?.flushRemaining() {
-      let processedPacket = converter?.transform(finalPacket) ?? finalPacket
+    audioBuffer?.processChunks().forEach { packet in
+      let processedPacket = converter?.transform(packet) ?? packet
       outputHandler.handleAudioPacket(processedPacket)
     }