Fix audio clock drift and adaptive jitter buffering

clients/apple/dotnet/VoiceCat.Mac/SettingsWindowController.cs

@@ -26,15 +26,18 @@ internal sealed class SettingsWindowController : NSWindowController
     private readonly NSButton pttSound = NSButton.CreateCheckbox("Push-to-talk cue", () => { });
     private readonly NSButton pttKey = new(new CGRect(220, 12, 200, 32)) { Title = "Change PTT key…" };
     private readonly NSSlider eventVolume = new(new CGRect(160, 505, 260, 24)) { MinValue = 0, MaxValue = 100 };
+    private readonly NSPopUpButton audioBuffer = new(new CGRect(160, 545, 260, 28), false);
 
     internal SettingsWindowController(MainWindowController owner, MacSettings settings, MacAudioBackend audio) : base(
-        new NSWindow(new CGRect(0, 0, 460, 620), NSWindowStyle.Titled | NSWindowStyle.Closable,
+        new NSWindow(new CGRect(0, 0, 460, 660), NSWindowStyle.Titled | NSWindowStyle.Closable,
             NSBackingStore.Buffered, false))
     {
         this.owner = owner; this.settings = settings; this.audio = audio;
         Window!.Title = "VoiceCat Settings"; Window.Center();
         NSView view = Window.ContentView!;
         mode.AddItems(["Voice activation", "Push to talk", "Always on"]);
+        audioBuffer.AddItems(["Low latency (20 ms)", "Balanced (40 ms)", "Stable (60 ms)"]);
+        Add(view, "Audio buffering", audioBuffer, 555);
         Add(view, "Sound volume", eventVolume, 515);
         Add(view, "Input mode", mode, 465); Add(view, "VAD sensitivity", vad, 425); Add(view, "Microphone volume", inputGain, 385);
         noiseReduction.Frame = new CGRect(160, 340, 260, 24); stereo.Frame = new CGRect(160, 315, 260, 24);
@@ -46,7 +49,7 @@ internal sealed class SettingsWindowController : NSWindowController
         selfTalk.Frame = new CGRect(265, 45, 180, 24); pttSound.Frame = new CGRect(25, 18, 180, 24);
         view.AddSubview(sounds); view.AddSubview(speech); view.AddSubview(selfTalk); view.AddSubview(pttSound); view.AddSubview(pttKey);
         foreach (NSControl control in new NSControl[] { mode, vad, inputGain, noiseReduction, stereo, input, output,
-            outputGain, auxiliary, auxiliaryDevice, auxiliaryGain, sounds, speech, selfTalk, pttSound, eventVolume }) control.Activated += Changed;
+            outputGain, auxiliary, auxiliaryDevice, auxiliaryGain, sounds, speech, selfTalk, pttSound, eventVolume, audioBuffer }) control.Activated += Changed;
         pttKey.Activated += CapturePushToTalkKey;
         Populate(input, true, settings.InputDeviceId); Populate(output, false, settings.OutputDeviceId); Populate(auxiliaryDevice, true, settings.AuxiliaryDeviceId);
         LoadValues(); SetAccessibility();
@@ -76,6 +79,7 @@ internal sealed class SettingsWindowController : NSWindowController
         eventVolume.DoubleValue = settings.EventVolume * 100;
         selfTalk.State = State(settings.SelfTalkSounds); pttSound.State = State(settings.PushToTalkSound);
         pttKey.Title = $"PTT key code: {settings.PushToTalkKeyCode}";
+        audioBuffer.SelectItem(settings.AudioBufferMilliseconds switch { 20 => 0, 60 => 2, _ => 1 });
         UpdateEnabled();
     }
 
@@ -102,6 +106,7 @@ internal sealed class SettingsWindowController : NSWindowController
         settings.AuxiliaryGain = (float)auxiliaryGain.DoubleValue / 100; settings.EventSounds = On(sounds);
         settings.EventVolume = (float)eventVolume.DoubleValue / 100; settings.SpokenEvents = On(speech);
         settings.SelfTalkSounds = On(selfTalk); settings.PushToTalkSound = On(pttSound);
+        settings.AudioBufferMilliseconds = audioBuffer.IndexOfSelectedItem switch { 0 => 20, 2 => 60, _ => 40 };
         settings.Save(); UpdateEnabled(); await owner.ApplySettingsAsync();
     }
 
@@ -113,6 +118,7 @@ internal sealed class SettingsWindowController : NSWindowController
         ((INSAccessibility)output).AccessibilityLabel = "Output device"; ((INSAccessibility)outputGain).AccessibilityLabel = "Output volume";
         ((INSAccessibility)auxiliaryDevice).AccessibilityLabel = "Auxiliary input device"; ((INSAccessibility)auxiliaryGain).AccessibilityLabel = "Auxiliary input volume";
         ((INSAccessibility)eventVolume).AccessibilityLabel = "Event sound volume";
+        ((INSAccessibility)audioBuffer).AccessibilityLabel = "Audio buffering";
     }
     private static bool On(NSButton button) => button.State == NSCellStateValue.On;
     private static NSCellStateValue State(bool value) => value ? NSCellStateValue.On : NSCellStateValue.Off;