feat: mono audio

index.html

@@ -2896,6 +2896,16 @@
                                         style="width: 80px"
                                     />
                                 </div>
+                                <div class="setting-item">
+                                    <div class="info">
+                                        <span class="label">Mono Audio</span>
+                                        <span class="description">Combine left and right channels into mono</span>
+                                    </div>
+                                    <label class="toggle-switch">
+                                        <input type="checkbox" id="mono-audio-toggle" />
+                                        <span class="slider"></span>
+                                    </label>
+                                </div>
 
                                 <!-- 16-Band Equalizer -->
                                 <div class="setting-item">

js/audio-context.js

@@ -1,7 +1,7 @@
 // js/audio-context.js
 // Shared Audio Context Manager - handles EQ and provides context for visualizer
 
-import { equalizerSettings } from './storage.js';
+import { equalizerSettings, monoAudioSettings } from './storage.js';
 
 // Standard 16-band ISO center frequencies (Hz)
 const EQ_FREQUENCIES = [25, 40, 63, 100, 160, 250, 400, 630, 1000, 1600, 2500, 4000, 6300, 10000, 16000, 20000];
@@ -83,6 +83,8 @@ class AudioContextManager {
         this.outputNode = null;
         this.isInitialized = false;
         this.isEQEnabled = false;
+        this.isMonoAudioEnabled = false;
+        this.monoMergerNode = null;
         this.currentGains = new Array(16).fill(0);
         this.audio = null;
 
@@ -168,13 +170,16 @@ class AudioContextManager {
             this.outputNode = this.audioContext.createGain();
             this.outputNode.gain.value = 1;
 
+            // Create mono audio merger node
+            this.monoMergerNode = this.audioContext.createChannelMerger(2);
+
             // Connect filter chain: filter[0] -> filter[1] -> ... -> filter[15] -> outputNode
             for (let i = 0; i < this.filters.length - 1; i++) {
                 this.filters[i].connect(this.filters[i + 1]);
             }
             this.filters[this.filters.length - 1].connect(this.outputNode);
 
-            // Connect the audio graph based on EQ state
+            // Connect the audio graph based on EQ and mono state
             this._connectGraph();
 
             this.isInitialized = true;
@@ -185,7 +190,7 @@ class AudioContextManager {
     }
 
     /**
-     * Connect the audio graph based on EQ enabled state
+     * Connect the audio graph based on EQ and mono audio state
      */
     _connectGraph() {
         if (!this.source || !this.audioContext) return;
@@ -194,6 +199,13 @@ class AudioContextManager {
             // Disconnect everything first
             this.source.disconnect();
             this.outputNode.disconnect();
+            if (this.monoMergerNode) {
+                try {
+                    this.monoMergerNode.disconnect();
+                } catch (e) {
+                    // Ignore if not connected
+                }
+            }
 
             // Only disconnect destination from analyser to preserve other taps (like Butterchurn)
             try {
@@ -202,15 +214,34 @@ class AudioContextManager {
                 // Ignore if not connected
             }
 
+            let lastNode = this.source;
+
+            // Apply mono audio if enabled
+            if (this.isMonoAudioEnabled && this.monoMergerNode) {
+                // Create a gain node to mix channels before the merger
+                const monoGain = this.audioContext.createGain();
+                monoGain.gain.value = 0.5; // Reduce volume to prevent clipping when mixing
+
+                // Connect source to mono gain
+                this.source.connect(monoGain);
+
+                // Connect mono gain to both inputs of the merger
+                monoGain.connect(this.monoMergerNode, 0, 0);
+                monoGain.connect(this.monoMergerNode, 0, 1);
+
+                lastNode = this.monoMergerNode;
+                console.log('[AudioContext] Mono audio enabled');
+            }
+
             if (this.isEQEnabled && this.filters.length > 0) {
-                // EQ enabled: source -> EQ filters -> output -> analyser -> destination
+                // EQ enabled: lastNode -> EQ filters -> output -> analyser -> destination
-                this.source.connect(this.filters[0]);
+                lastNode.connect(this.filters[0]);
                 this.outputNode.connect(this.analyser);
                 this.analyser.connect(this.audioContext.destination);
                 console.log('[AudioContext] EQ connected');
             } else {
-                // EQ disabled: source -> analyser -> destination
+                // EQ disabled: lastNode -> analyser -> destination
-                this.source.connect(this.analyser);
+                lastNode.connect(this.analyser);
                 this.analyser.connect(this.audioContext.destination);
                 console.log('[AudioContext] EQ bypassed');
             }
@@ -303,6 +334,27 @@ class AudioContextManager {
         return this.isInitialized && this.isEQEnabled;
     }
 
+    /**
+     * Toggle mono audio on/off
+     */
+    toggleMonoAudio(enabled) {
+        this.isMonoAudioEnabled = enabled;
+        monoAudioSettings.setEnabled(enabled);
+
+        if (this.isInitialized) {
+            this._connectGraph();
+        }
+
+        return this.isMonoAudioEnabled;
+    }
+
+    /**
+     * Check if mono audio is active
+     */
+    isMonoAudioActive() {
+        return this.isInitialized && this.isMonoAudioEnabled;
+    }
+
     /**
      * Set gain for a specific band
      */
@@ -372,6 +424,7 @@ class AudioContextManager {
     _loadSettings() {
         this.isEQEnabled = equalizerSettings.isEnabled();
         this.currentGains = equalizerSettings.getGains();
+        this.isMonoAudioEnabled = monoAudioSettings.isEnabled();
     }
 }
 

js/settings.js

@@ -24,6 +24,7 @@ import {
     homePageSettings,
     sidebarSectionSettings,
     fontSettings,
+    monoAudioSettings,
 } from './storage.js';
 import { audioContextManager, EQ_PRESETS } from './audio-context.js';
 import { getButterchurnPresets } from './visualizers/butterchurn.js';
@@ -690,6 +691,17 @@ export function initializeSettings(scrobbler, player, api, ui) {
         });
     }
 
+    // Mono Audio Toggle
+    const monoAudioToggle = document.getElementById('mono-audio-toggle');
+    if (monoAudioToggle) {
+        monoAudioToggle.checked = monoAudioSettings.isEnabled();
+        monoAudioToggle.addEventListener('change', (e) => {
+            const enabled = e.target.checked;
+            monoAudioSettings.setEnabled(enabled);
+            audioContextManager.toggleMonoAudio(enabled);
+        });
+    }
+
     // ========================================
     // 16-Band Equalizer Settings
     // ========================================

js/storage.js

@@ -844,6 +844,22 @@ export const equalizerSettings = {
     },
 };
 
+export const monoAudioSettings = {
+    STORAGE_KEY: 'mono-audio-enabled',
+
+    isEnabled() {
+        try {
+            return localStorage.getItem(this.STORAGE_KEY) === 'true';
+        } catch {
+            return false;
+        }
+    },
+
+    setEnabled(enabled) {
+        localStorage.setItem(this.STORAGE_KEY, enabled ? 'true' : 'false');
+    },
+};
+
 export const sidebarSettings = {
     STORAGE_KEY: 'monochrome-sidebar-collapsed',