TASK 9 audio milestone: real stream audio + voice filters + auto-duck + free TRAX music — the mixer now feeds the encoder real audio (ffmpeg reads a Windows named pipe, -f f32le -ar 48000 -ac 2 -i \.\pipe\ytllive_audio, replacing anullsrc silence; explicit -map 0:v -map 1:a via EncoderOptions.AudioPipeName), with honest gains reaching the stream (MicVolume scales mic, GameAudioVolume + mute scale loopback, Func<double> seams on AudioMixer), an always-on pure-C# voice chain on the mic BEFORE the meter and mix (LowShelfFilter 120Hz +4dB → HighShelfFilter 8kHz +3dB → NoiseGate 0.005/hysteresis 0.5 → Compressor 0.5 4:1, all TDF2), AutoDucker (mic RMS>0.02 → loopback ×0.25, attack 0.05/release 0.005), and TRAX free background music (MusicPlayer = MediaFoundationReader → VolumeWaveProvider16 at fixed 0.20 → WaveOutEvent via the new sibling NAudio.WinMM 2.2.1 package; plays to the default device so the existing loopback carries it, ducked with game; footer TRAX button with red/yellow/green status dot, left-click toggles/picks, right-click opens the OpenFileDialog picker, tooltip shows the track name; persisted via schema v9 single-row Music). Build-time deviations from the plan (recorded in ai.md + TASKS.md): WasapiCapture in NAudio 2.2.1 exposes no overridable GetDefaultMixFormat so sources run device mix format and the mixer's TinyResampler normalizes any rate to 48kHz (resampler IS the design); FfmpegEncoder.cs untouched — MainViewModel.StopStream calls _audioMixer.StopLive() (pipe EOF) before the frame pump stops; sound-bar relabelled 'Desktop Audio', IsGameAudioBarVisible = game sound OR music playing. Tests: new AudioPipelineTests (DSP/ring-buffer/ducker/resampler units + the ONE integration test Mix_WithFiltersDuckAndGain_Lands_On_AudioPipe reading real pipe bytes; ring-buffer overwrite bug found + fixed), FfmpegEncoderTests/LayoutStorePersistenceTests updated — 196 tests passing, 0 warnings

Services/Encoder/EncoderOptions.cs

@@ -4,11 +4,15 @@ namespace ytLive.Services.Encoder;
 /// Everything the FFmpeg subprocess encoder needs for one go-live (TASK 4 ship
 /// step 3). <see cref="RtmpUrl"/> is the FULL ingestion URL — the reusable
 /// stream's ingest address plus its stream key (<c>rtmp://a.rtmp.youtube.com/live2/&lt;key&gt;</c>).
-/// Resolution/FPS/bitrate come from the active quality tier; audio is a silent
-/// placeholder track until the WASAPI capture step replaces the input.
+/// Resolution/FPS/bitrate come from the active quality tier; audio (TASK 9)
+/// streams from the mixer through the named pipe <see cref="AudioPipeName"/>.
 /// </summary>
 public sealed class EncoderOptions
 {
+    /// <summary>The audio pipe the mixer streams into; the args reference the
+    /// same name for ffmpeg's <c>-i</c>.</summary>
+    public const string DefaultAudioPipeName = "ytllive_audio";
+
     public string RtmpUrl { get; init; } = string.Empty;
     public int Width { get; init; } = 1920;
     public int Height { get; init; } = 1080;
@@ -22,6 +26,9 @@ public sealed class EncoderOptions
     public int AudioSampleRate { get; init; } = 48000;
     public int AudioChannels { get; init; } = 2;
 
+    /// <summary>Name of the mixer's audio pipe (default <see cref="DefaultAudioPipeName"/>).</summary>
+    public string AudioPipeName { get; init; } = DefaultAudioPipeName;
+
     /// <summary>GOP in frames = Fps × 4s — the YouTube keyframe ≤ 4s compliance bound.</summary>
     public int GopSize => Fps * 4;
 }

Services/Encoder/FfmpegArgs.cs

@@ -2,10 +2,11 @@ namespace ytLive.Services.Encoder;
 
 /// <summary>
 /// Builds the FFmpeg command line for a live RTMP push (TASK 4 ship step 3):
-/// raw BGRA frames via stdin (paced <c>-re</c>), silent placeholder audio via lavfi
-/// <c>anullsrc</c> (the WASAPI step replaces this input), H.264 + AAC encoding, FLV
-/// muxing to the ingestion URL. Pure — the encoder just starts
-/// <c>ffmpeg.exe [Build(...)]</c>.
+/// raw BGRA frames via stdin (paced <c>-re</c>), real audio via the named pipe
+/// (TASK 9 — the mixer streams f32le at 48 kHz stereo into <c>\\.\pipe\&lt;name&gt;</c>;
+/// WASAPI loopback + the mic ride the pipe instead of the old anullsrc silence),
+/// H.264 + AAC encoding, FLV muxing to the ingestion URL. Pure — the encoder
+/// just starts <c>ffmpeg.exe [Build(...)]</c>.
 /// </summary>
 public static class FfmpegArgs
 {
@@ -24,8 +25,12 @@ public static class FfmpegArgs
             "-video_size", $"{options.Width}x{options.Height}",
             "-framerate", options.Fps.ToString(),
             "-i", "pipe:0",
-            "-f", "lavfi",
-            "-i", $"anullsrc=channel_layout=stereo:sample_rate={options.AudioSampleRate}",
+            "-f", "f32le",
+            "-ar", options.AudioSampleRate.ToString(),
+            "-ac", options.AudioChannels.ToString(),
+            "-i", $@"\\.\pipe\{options.AudioPipeName}",
+            "-map", "0:v",
+            "-map", "1:a",
             "-c:v", videoEncoder,
             "-b:v", $"{options.BitrateKbps}k",
             "-maxrate", $"{options.BitrateKbps}k",