fix: stereo sample downmix in track panners which causes the sampled sounds (both MIDI and audio tracks) are quieter than it should be

.gitignore

@@ -28,3 +28,5 @@ DEPLOYMENT.md
 *.sln
 *.sw?
 *.psd
+audio-debug.html
+src/audio-debug.ts

src/components/piano-roll/PianoKeys.tsx

@@ -243,4 +243,4 @@ const PianoKeys: React.FC<PianoKeysProps> = ({ activeRegion }) => {
   );
 };
 
-export default PianoKeys; 
+export default PianoKeys;

src/core/audio-interface/KGAudioBus.ts

@@ -4,6 +4,7 @@ import { FLUIDR3_INSTRUMENT_MAP } from '../../constants/generalMidiConstants';
 import type { InstrumentType } from '../track/KGMidiTrack';
 import { KGToneBuffersPool } from './KGToneBuffersPool';
 import { KGToneSamplerFactory } from './KGToneSamplerFactory';
+import { createStereoTrackPanner } from './createStereoTrackPanner';
 
 // InstrumentType is defined in KGMidiTrack and re-used here
 
@@ -100,7 +101,7 @@ export class KGAudioBus {
       ]);
       
       // Create the audio bus instance
-      const panner = new Tone.Panner(pan);
+      const panner = createStereoTrackPanner(pan);
       sampler.connect(panner);
       const audioBus = new KGAudioBus(sampler, audioBuffers, instrument, panner, volume, pan, muted, solo);
       

src/core/audio-interface/KGAudioInterface.ts

@@ -953,7 +953,7 @@ export class KGAudioInterface {
       const normalizedVelocity = velocity / 127; // Normalize to 0-1
       const triggerTime = time ?? Tone.now();
       this.applyTrackAutomationForCurrentBeat(trackId);
-      
+
       // Check if track should play considering solo logic
       const hasSoloedTracks = this.hasSoloedTracks();
       if (audioBus.shouldPlayWithSolo(hasSoloedTracks)) {

src/core/audio-interface/KGAudioPlayerBus.ts

@@ -1,5 +1,6 @@
 import * as Tone from 'tone';
 import { AUDIO_INTERFACE_CONSTANTS } from '../../constants/coreConstants';
+import { createStereoTrackPanner } from './createStereoTrackPanner';
 
 /**
  * KGAudioPlayerBus - Represents an audio playback bus for a track.
@@ -61,7 +62,7 @@ export class KGAudioPlayerBus {
   ): Promise<KGAudioPlayerBus> {
     try {
       const gainNode = new Tone.Gain(1);
-      const pannerNode = new Tone.Panner(pan);
+      const pannerNode = createStereoTrackPanner(pan);
       gainNode.connect(pannerNode);
       const bus = new KGAudioPlayerBus(gainNode, pannerNode, volume, pan, muted, solo);
       console.log('KGAudioPlayerBus created successfully');

src/core/audio-interface/KGOfflineRenderer.ts

@@ -29,6 +29,7 @@ import { beatRangeToSeconds, beatToSeconds, findGlobalTrackByType, getEffectiveB
 import { GlobalTrackType } from '../global-track';
 import { ConfigManager } from '../config/ConfigManager';
 import { Mp3Encoder } from '@breezystack/lamejs';
+import { createStereoTrackPanner } from './createStereoTrackPanner';
 
 export interface RenderOptions {
   sampleRate?: number;  // default 44100
@@ -332,7 +333,7 @@ export class KGOfflineRenderer {
             // Track volumes are stored in dB across the app, with 0 meaning unity gain.
             sampler.volume.value = 0;
             const trackGain = new Tone.Gain(getOfflineTrackGain(trackInfo.volume, trackInfo.muted));
-            const trackPanner = new Tone.Panner(0);
+            const trackPanner = createStereoTrackPanner(0);
             sampler.connect(trackGain);
             trackGain.connect(trackPanner);
             trackPanner.connect(masterGain);
@@ -439,7 +440,7 @@ export class KGOfflineRenderer {
         if (!shouldPlay(trackInfo, hasSoloedTracks)) continue;
 
         const trackGain = new Tone.Gain(getOfflineTrackGain(trackInfo.volume, trackInfo.muted));
-        const trackPanner = new Tone.Panner(0);
+        const trackPanner = createStereoTrackPanner(0);
         trackGain.connect(trackPanner);
         trackPanner.connect(masterGain);
         applyOfflineTrackAutomation(

src/core/audio-interface/createStereoTrackPanner.ts

@@ -0,0 +1,8 @@
+import * as Tone from 'tone';
+
+export function createStereoTrackPanner(pan: number = 0): Tone.Panner {
+  return new Tone.Panner({
+    pan,
+    channelCount: 2,
+  });
+}