add stereo recording option

Sources/CLI/AudioTee.swift

@@ -5,6 +5,7 @@ struct AudioTee {
   var includeProcesses: [Int32] = []
   var excludeProcesses: [Int32] = []
   var mute: Bool = false
+  var stereo: Bool = false
   var sampleRate: Double?
   var chunkDuration: Double = 0.2
 
@@ -40,6 +41,7 @@ struct AudioTee {
     parser.addArrayOption(
       name: "exclude-processes", help: "Process IDs to exclude (space-separated)")
     parser.addFlag(name: "mute", help: "Mute processes being tapped")
+    parser.addFlag(name: "stereo", help: "Records in stereo")
     parser.addOption(
       name: "sample-rate",
       help: "Target sample rate (8000, 16000, 22050, 24000, 32000, 44100, 48000)")
@@ -56,6 +58,7 @@ struct AudioTee {
       audioTee.includeProcesses = try parser.getArrayValue("include-processes", as: Int32.self)
       audioTee.excludeProcesses = try parser.getArrayValue("exclude-processes", as: Int32.self)
       audioTee.mute = parser.getFlag("mute")
+      audioTee.stereo = parser.getFlag("stereo")
       audioTee.sampleRate = try parser.getOptionalValue("sample-rate", as: Double.self)
       audioTee.chunkDuration = try parser.getValue("chunk-duration", as: Double.self)
 
@@ -107,7 +110,8 @@ struct AudioTee {
     let tapConfig = TapConfiguration(
       processes: processes,
       muteBehavior: mute ? .muted : .unmuted,
-      isExclusive: isExclusive
+      isExclusive: isExclusive,
+      isMono: !stereo
     )
 
     let audioTapManager = AudioTapManager()

Sources/CLI/TapConfiguration.swift

@@ -2,10 +2,12 @@ public struct TapConfiguration {
   public let processes: [Int32]
   public let muteBehavior: TapMuteBehavior
   public let isExclusive: Bool
+  public let isMono: Bool
 
-  public init(processes: [Int32], muteBehavior: TapMuteBehavior, isExclusive: Bool) {
+  public init(processes: [Int32], muteBehavior: TapMuteBehavior, isExclusive: Bool, isMono: Bool) {
     self.processes = processes
     self.muteBehavior = muteBehavior
     self.isExclusive = isExclusive
+    self.isMono = isMono
   }
 }

Sources/Core/AudioFormatConverter.swift

@@ -130,11 +130,11 @@ public class AudioFormatConverter {
     targetFormat.mSampleRate = sampleRate
     targetFormat.mFormatID = kAudioFormatLinearPCM
     targetFormat.mFormatFlags = kAudioFormatFlagIsPacked | kAudioFormatFlagIsSignedInteger
-    targetFormat.mBytesPerPacket = 2
     targetFormat.mFramesPerPacket = 1
-    targetFormat.mBytesPerFrame = 2
-    targetFormat.mChannelsPerFrame = 1  // Always mono since tap handles this
     targetFormat.mBitsPerChannel = 16
+    targetFormat.mChannelsPerFrame = sourceFormat.mChannelsPerFrame
+    targetFormat.mBytesPerFrame = (targetFormat.mBitsPerChannel / 8) * sourceFormat.mChannelsPerFrame
+    targetFormat.mBytesPerPacket = targetFormat.mFramesPerPacket * targetFormat.mBytesPerFrame
 
     return try AudioFormatConverter(sourceFormat: sourceFormat, targetFormat: targetFormat)
   }

Sources/Core/AudioTapManager.swift

@@ -57,7 +57,7 @@ class AudioTapManager {
     description.isPrivate = true
     description.muteBehavior = config.muteBehavior.coreAudioValue
     description.isMixdown = true
-    description.isMono = true
+    description.isMono = config.isMono
     description.isExclusive = config.isExclusive
     description.deviceUID = nil  // system default
     description.stream = 0  // first stream of output device