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 +1,92 @@
+using ytLive.Services;
+
+namespace ytLive.Services.Audio;
+
+/// <summary>
+/// Owns the mic + desktop/game capture sources (TASK 4 ship step 4) and drives
+/// the live mic meter. Runs only while live: started when go-live succeeds,
+/// stopped on end-stream. Mic samples are level-metered and forwarded; loopback
+/// samples are currently dropped (consumed by the encoder mix in a later step).
+/// </summary>
+public sealed class AudioMixer : IDisposable
+{
+    private readonly IAudioSource _mic;
+    private readonly IAudioSource _loopback;
+    private readonly AudioLevelMeter _meter;
+    private readonly Action<string>? _log;
+    private bool _started;
+
+    public AudioMixer(IAudioSource mic, IAudioSource loopback, Action<string>? log = null)
+    {
+        _mic = mic;
+        _loopback = loopback;
+        _meter = new AudioLevelMeter();
+        _log = log;
+
+        _mic.SampleReady += OnMicSample;
+        _loopback.SampleReady += OnLoopbackSample;
+        _mic.Failed += OnMicFailed;
+        _loopback.Failed += OnLoopbackFailed;
+    }
+
+    /// <summary>Current smoothed mic level (0..1).</summary>
+    public float MicLevel => _meter.Level;
+
+    /// <summary>Raised whenever the smoothed mic level changes.</summary>
+    public event Action<float>? MicLevelChanged;
+
+    public void Start()
+    {
+        if (_started)
+            return;
+
+        _started = true;
+        _meter.Reset();
+        _loopback.Start();
+        _mic.Start();
+    }
+
+    public void Stop()
+    {
+        if (!_started)
+            return;
+
+        _started = false;
+        _mic.Stop();
+        _loopback.Stop();
+        _meter.Reset();
+        MicLevelChanged?.Invoke(0);
+    }
+
+    public void Dispose()
+    {
+        Stop();
+        _mic.SampleReady -= OnMicSample;
+        _loopback.SampleReady -= OnLoopbackSample;
+        _mic.Failed -= OnMicFailed;
+        _loopback.Failed -= OnLoopbackFailed;
+        _mic.Dispose();
+        _loopback.Dispose();
+    }
+
+    private void OnMicSample(AudioSample sample)
+    {
+        MicLevelChanged?.Invoke(_meter.Push(sample));
+    }
+
+    private void OnLoopbackSample(AudioSample sample)
+    {
+        // Desktop/game audio: captured for the future encoder mix; no UI yet.
+    }
+
+    private void OnMicFailed(Exception ex)
+    {
+        _log?.Invoke($"Mic capture failed: {ex.Message}");
+        MicLevelChanged?.Invoke(0);
+    }
+
+    private void OnLoopbackFailed(Exception ex)
+    {
+        _log?.Invoke($"Desktop audio capture failed: {ex.Message}");
+    }
+}