TASK 4 ship step 4: WASAPI audio capture — NAudio loopback + mic behind an IAudioSource seam, AudioMixer driving AudioLevel while live, pure level meter + WaveToFloat, NAudio.Wasapi 2.2.1 (MIT, notices item 9) — 139 tests passing, 0 warnings

2026-08-12 21:18:07 -07:00
parent ba427e85e1
commit 58c0f8e8c4
16 changed files with 814 additions and 34 deletions
@@ -0,0 +1,102 @@
+using NAudio.CoreAudioApi;
+using NAudio.Wave;
+
+namespace ytLive.Services.Audio;
+
+/// <summary>
+/// Captures the selected microphone (TASK 4 ship step 4) via WASAPI. Resolves
+/// the NAudio device by FriendlyName matching <c>MicSourceName</c> (the app only
+/// persists DisplayName), falling back to the default capture endpoint.
+/// </summary>
+public sealed class WasapiMicAudioSource : IAudioSource
+{
+    private readonly Func<string?> _micNameProvider;
+    private WasapiCapture? _capture;
+
+    /// <param name="micNameProvider">Returns the current mic DisplayName; read
+    /// at each Start so a device picked mid-session takes effect next go-live.</param>
+    public WasapiMicAudioSource(Func<string?> micNameProvider)
+    {
+        _micNameProvider = micNameProvider;
+    }
+
+    public event Action<AudioSample>? SampleReady;
+    public event Action<Exception>? Failed;
+
+    public void Start()
+    {
+        if (_capture != null)
+            throw new InvalidOperationException("Already started.");
+
+        try
+        {
+            var device = ResolveDevice();
+            _capture = device != null ? new WasapiCapture(device) : new WasapiCapture();
+            _capture.DataAvailable += OnDataAvailable;
+            _capture.RecordingStopped += OnRecordingStopped;
+            _capture.StartRecording();
+        }
+        catch (Exception ex)
+        {
+            Stop();
+            Failed?.Invoke(ex);
+        }
+    }
+
+    public void Stop()
+    {
+        if (_capture == null)
+            return;
+
+        try
+        {
+            _capture.StopRecording();
+        }
+        catch
+        {
+        }
+        _capture.Dispose();
+        _capture = null;
+    }
+
+    public void Dispose() => Stop();
+
+    private MMDevice? ResolveDevice()
+    {
+        var micName = _micNameProvider();
+        if (string.IsNullOrWhiteSpace(micName))
+            return null;
+
+        try
+        {
+            using var enumerator = new MMDeviceEnumerator();
+            foreach (var endpoint in enumerator.EnumerateAudioEndPoints(DataFlow.Capture, DeviceState.Active))
+            {
+                if (string.Equals(endpoint.FriendlyName, micName, StringComparison.OrdinalIgnoreCase))
+                    return endpoint;
+            }
+        }
+        catch
+        {
+        }
+
+        return null;
+    }
+
+    private void OnDataAvailable(object? sender, WaveInEventArgs e)
+    {
+        if (e.BytesRecorded <= 0)
+            return;
+
+        var format = _capture?.WaveFormat ?? WaveFormat.CreateIeeeFloatWaveFormat(48000, 1);
+        var samples = WaveToFloat.Convert(e.Buffer, e.BytesRecorded, format);
+        if (samples.Length > 0)
+            SampleReady?.Invoke(new AudioSample(samples, format.SampleRate, format.Channels));
+    }
+
+    private void OnRecordingStopped(object? sender, StoppedEventArgs e)
+    {
+        if (e.Exception != null)
+            Failed?.Invoke(e.Exception);
+    }
+}