fix: recover from microphone disconnects

MeetingAssistant/Recording/IMicrophoneCaptureSourceFactory.cs

@@ -0,0 +1,6 @@
+namespace MeetingAssistant.Recording;
+
+public interface IMicrophoneCaptureSourceFactory
+{
+    IMeetingAudioSource CreateCapture(MeetingAssistantOptions options);
+}

MeetingAssistant/Recording/IMicrophoneDeviceProvider.cs

@@ -1,5 +1,3 @@
-using NAudio.Wave;
-
 namespace MeetingAssistant.Recording;
 
 public interface IMicrophoneDeviceProvider
@@ -7,6 +5,4 @@ public interface IMicrophoneDeviceProvider
     IReadOnlyList<MicrophoneDevice> GetAvailableMicrophones();
 
     MicrophoneDeviceSnapshot GetMicrophoneSnapshot(MeetingAssistantOptions options);
-
-    IWaveIn CreateCapture(MeetingAssistantOptions options);
 }

MeetingAssistant/Recording/MicrophoneAudioSource.cs

@@ -0,0 +1,145 @@
+using System.Runtime.CompilerServices;
+
+namespace MeetingAssistant.Recording;
+
+public sealed class MicrophoneAudioSource : IMeetingAudioSource
+{
+    private static readonly TimeSpan DefaultRecoveryDelay = TimeSpan.FromSeconds(1);
+    private readonly IMicrophoneCaptureSourceFactory captureSources;
+    private readonly ILogger<MicrophoneAudioSource> logger;
+    private readonly TimeSpan recoveryDelay;
+
+    public MicrophoneAudioSource(
+        IMicrophoneCaptureSourceFactory captureSources,
+        ILogger<MicrophoneAudioSource> logger)
+        : this(captureSources, logger, DefaultRecoveryDelay)
+    {
+    }
+
+    internal MicrophoneAudioSource(
+        IMicrophoneCaptureSourceFactory captureSources,
+        ILogger<MicrophoneAudioSource> logger,
+        TimeSpan recoveryDelay)
+    {
+        this.captureSources = captureSources;
+        this.logger = logger;
+        this.recoveryDelay = recoveryDelay;
+    }
+
+    public IAsyncEnumerable<AudioChunk> CaptureAsync(CancellationToken cancellationToken)
+    {
+        return CaptureAsync(new MeetingAssistantOptions(), cancellationToken);
+    }
+
+    public async IAsyncEnumerable<AudioChunk> CaptureAsync(
+        MeetingAssistantOptions options,
+        [EnumeratorCancellation] CancellationToken cancellationToken)
+    {
+        var failedAttempts = 0;
+        while (!cancellationToken.IsCancellationRequested)
+        {
+            IAsyncEnumerator<AudioChunk>? capture = null;
+            Exception? failure = null;
+
+            try
+            {
+                capture = captureSources
+                    .CreateCapture(options)
+                    .CaptureAsync(options, cancellationToken)
+                    .GetAsyncEnumerator(cancellationToken);
+            }
+            catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested)
+            {
+            }
+            catch (Exception exception)
+            {
+                failure = exception;
+            }
+
+            if (cancellationToken.IsCancellationRequested)
+            {
+                yield break;
+            }
+
+            if (capture is not null)
+            {
+                try
+                {
+                    while (!cancellationToken.IsCancellationRequested)
+                    {
+                        var hasNext = false;
+                        try
+                        {
+                            hasNext = await capture.MoveNextAsync();
+                        }
+                        catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested)
+                        {
+                        }
+                        catch (Exception exception)
+                        {
+                            failure = exception;
+                        }
+
+                        if (cancellationToken.IsCancellationRequested || failure is not null || !hasNext)
+                        {
+                            break;
+                        }
+
+                        if (failedAttempts > 0)
+                        {
+                            logger.LogInformation(
+                                "Microphone capture recovered after {FailedAttemptCount} failed attempt(s)",
+                                failedAttempts);
+                            failedAttempts = 0;
+                        }
+
+                        yield return capture.Current;
+                    }
+                }
+                finally
+                {
+                    try
+                    {
+                        await capture.DisposeAsync();
+                    }
+                    catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested)
+                    {
+                    }
+                    catch (Exception exception)
+                    {
+                        failure ??= exception;
+                    }
+                }
+            }
+
+            if (cancellationToken.IsCancellationRequested)
+            {
+                yield break;
+            }
+
+            failedAttempts++;
+            logger.LogWarning(
+                failure,
+                "Microphone capture stopped unexpectedly; re-resolving an available microphone in {RecoveryDelay}",
+                recoveryDelay);
+
+            if (!await WaitForRecoveryAsync(cancellationToken))
+            {
+                yield break;
+            }
+        }
+    }
+
+    private async Task<bool> WaitForRecoveryAsync(CancellationToken cancellationToken)
+    {
+        try
+        {
+            await Task.Delay(recoveryDelay, cancellationToken);
+            return true;
+        }
+        catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested)
+        {
+            return false;
+        }
+    }
+}

MeetingAssistant/Recording/MicrophoneDeviceSelection.cs

@@ -34,6 +34,8 @@ public sealed class MicrophoneDeviceSelection
         var selected = SelectedDeviceId;
         return FindById(availableDevices, selected) ??
             FindById(availableDevices, configuredDeviceId) ??
+            FindById(availableDevices, defaultDevice?.Id) ??
+            availableDevices.FirstOrDefault() ??
             defaultDevice;
     }
 

MeetingAssistant/Recording/NaudioCaptureSource.cs

@@ -4,41 +4,28 @@ using NAudio.Wave;
 
 namespace MeetingAssistant.Recording;
 
-public sealed class MicrophoneAudioSource : IMeetingAudioSource
+internal sealed class NaudioCaptureAudioSource : IMeetingAudioSource
 {
-    private readonly IMicrophoneDeviceProvider microphones;
-    private readonly ILogger<MicrophoneAudioSource> logger;
+    private readonly IWaveIn capture;
+    private readonly string sourceName;
+    private readonly ILogger logger;
 
-    public MicrophoneAudioSource(
-        IMicrophoneDeviceProvider microphones,
-        ILogger<MicrophoneAudioSource> logger)
+    public NaudioCaptureAudioSource(
+        IWaveIn capture,
+        string sourceName,
+        ILogger logger)
     {
-        this.microphones = microphones;
+        this.capture = capture;
+        this.sourceName = sourceName;
         this.logger = logger;
     }
 
     public IAsyncEnumerable<AudioChunk> CaptureAsync(CancellationToken cancellationToken)
     {
-        return CaptureAsync(new MeetingAssistantOptions(), cancellationToken);
+        return CaptureWith(capture, sourceName, logger, cancellationToken);
     }
 
-    public IAsyncEnumerable<AudioChunk> CaptureAsync(
-        MeetingAssistantOptions options,
-        CancellationToken cancellationToken)
-    {
-        return CaptureAsync(microphones.CreateCapture(options), options, cancellationToken);
-    }
-
-    private IAsyncEnumerable<AudioChunk> CaptureAsync(
-        IWaveIn capture,
-        MeetingAssistantOptions options,
-        CancellationToken cancellationToken)
-    {
-        capture.WaveFormat = new WaveFormat(options.Recording.SampleRate, 16, options.Recording.Channels);
-        return CaptureWith(capture, "microphone", logger, cancellationToken);
-    }
-
-    internal static async IAsyncEnumerable<AudioChunk> CaptureWith(
+    private static async IAsyncEnumerable<AudioChunk> CaptureWith(
         IWaveIn capture,
         string sourceName,
         ILogger logger,
@@ -124,6 +111,6 @@ public sealed class SystemAudioSource : IMeetingAudioSource
             WaveFormat = new WaveFormat(options.Recording.SampleRate, 16, options.Recording.Channels)
         };
 
-        return MicrophoneAudioSource.CaptureWith(capture, "system", logger, cancellationToken);
+        return new NaudioCaptureAudioSource(capture, "system", logger).CaptureAsync(cancellationToken);
     }
 }

MeetingAssistant/Recording/WindowsMicrophoneDeviceProvider.cs

@@ -3,7 +3,7 @@ using NAudio.Wave;
 
 namespace MeetingAssistant.Recording;
 
-public sealed class WindowsMicrophoneDeviceProvider : IMicrophoneDeviceProvider
+public sealed class WindowsMicrophoneDeviceProvider : IMicrophoneDeviceProvider, IMicrophoneCaptureSourceFactory
 {
     private readonly MicrophoneDeviceSelection selection;
     private readonly ILogger<WindowsMicrophoneDeviceProvider> logger;
@@ -42,21 +42,38 @@ public sealed class WindowsMicrophoneDeviceProvider : IMicrophoneDeviceProvider
             selection.Resolve(options.Recording.MicrophoneDeviceId, GetDefaultMicrophone(), devices));
     }
 
-    public IWaveIn CreateCapture(MeetingAssistantOptions options)
+    public IMeetingAudioSource CreateCapture(MeetingAssistantOptions options)
     {
         var current = GetMicrophoneSnapshot(options).Current;
+        IWaveIn capture;
         if (current is null)
         {
             logger.LogInformation("Starting microphone capture from Windows default capture endpoint");
-            return new WasapiCapture();
+            capture = new WasapiCapture();
+        }
+        else
+        {
+            logger.LogInformation(
+                "Starting microphone capture from {MicrophoneName} ({MicrophoneDeviceId})",
+                current.Name,
+                current.Id);
+            using var enumerator = new MMDeviceEnumerator();
+            capture = new WasapiCapture(enumerator.GetDevice(current.Id));
         }
 
-        logger.LogInformation(
-            "Starting microphone capture from {MicrophoneName} ({MicrophoneDeviceId})",
-            current.Name,
-            current.Id);
-        using var enumerator = new MMDeviceEnumerator();
-        return new WasapiCapture(enumerator.GetDevice(current.Id));
+        try
+        {
+            capture.WaveFormat = new WaveFormat(
+                options.Recording.SampleRate,
+                16,
+                options.Recording.Channels);
+            return new NaudioCaptureAudioSource(capture, "microphone", logger);
+        }
+        catch
+        {
+            capture.Dispose();
+            throw;
+        }
     }
 
     private static MicrophoneDevice? GetDefaultMicrophone()