From 89dc5db53c73a6fe73c3207e7daca5c9de0b6054 Mon Sep 17 00:00:00 2001
From: Dejvino <dejvino@gmail.com>
Date: Sun, 4 Jan 2026 22:17:41 +0000
Subject: [PATCH] Feature: complex BPM detection via multiple approaches

---
 party-stage/src/scene/music-visualizer.js | 102 ++++++++++++++++------
 1 file changed, 75 insertions(+), 27 deletions(-)

diff --git a/party-stage/src/scene/music-visualizer.js b/party-stage/src/scene/music-visualizer.js
index df3002d..84b1e27 100644
--- a/party-stage/src/scene/music-visualizer.js
+++ b/party-stage/src/scene/music-visualizer.js
@@ -38,6 +38,17 @@ export class MusicVisualizer extends SceneFeature {
         this.beatPhase = 0;
         this.measurePhase = 0;
         this.averageLoudness = 0;
+        this.prevLoudness = 0;
+        this.prevLoudnessLows = 0;
+        this.prevLoudnessHighs = 0;
+        this.beatSignalAvg = 0;
+
+        // 3 Detectors: Lows (Bass), Highs (Snare/Hats), Flux (All)
+        this.detectors = [
+            { name: 'low', lastTime: 0, threshold: 0.3, intervals: [], bpm: 120, weight: 1.0 },
+            { name: 'high', lastTime: 0, threshold: 0.3, intervals: [], bpm: 120, weight: 0.5 },
+            { name: 'flux', lastTime: 0, threshold: 0.3, intervals: [], bpm: 120, weight: 0.8 }
+        ];
     }
 
     update(deltaTime) {
@@ -95,40 +106,77 @@ export class MusicVisualizer extends SceneFeature {
         state.music.averageLoudness = this.averageLoudness;
 
         // --- Beat Detection & Auto-BPM ---
-        // Use Lows (Bass) for clearer beat detection
-        const beatSignal = state.music.loudnessLows || 0;
-        const beatAvg = state.music.loudnessLowsAverage || 0;
-
-        // Decay threshold based on time
-        this.beatThreshold -= deltaTime * 0.5;
-        const thresholdFloor = Math.max(0.15, beatAvg * 1.1);
-        if (this.beatThreshold < thresholdFloor) this.beatThreshold = thresholdFloor;
-
-        state.music.beatThreshold = this.beatThreshold;
+        // 1. Calculate derivatives for 3 bands
+        const dLows = Math.max(0, state.music.loudnessLows - this.prevLoudnessLows);
+        const dHighs = Math.max(0, state.music.loudnessHighs - this.prevLoudnessHighs);
+        const dAll = Math.max(0, state.music.loudness - this.prevLoudness);
+        
+        this.prevLoudnessLows = state.music.loudnessLows;
+        this.prevLoudnessHighs = state.music.loudnessHighs;
+        this.prevLoudness = state.music.loudness;
 
+        const signals = [dLows * 10.0, dHighs * 10.0, dAll * 10.0];
         const now = time;
-        const lastBeatInterval = now - this.lastBeatTime;
-        if (beatSignal > this.beatThreshold) {
-            if (lastBeatInterval > 0.25) { // Min interval (~240 BPM)
-                this.lastBeatTime = now;
-                this.beatThreshold = beatSignal * 1.2; // Bump threshold
+        let mainTrigger = false;
 
-                // Add only valid BPM range into history of beats
-                if (lastBeatInterval >= 0.2 && lastBeatInterval <= 1.5) {
-                    this.beatIntervals.push(lastBeatInterval);
-                    if (this.beatIntervals.length > 8) this.beatIntervals.shift();
+        // 2. Update Detectors
+        this.detectors.forEach((d, i) => {
+            const signal = signals[i];
+            
+            // Decay threshold
+            d.threshold -= deltaTime * 1.5;
+            const floor = 0.15;
+            if (d.threshold < floor) d.threshold = floor;
 
-                    const avgInterval = this.beatIntervals.reduce((a, b) => a + b, 0) / this.beatIntervals.length;
+            if (signal > d.threshold) {
+                const interval = now - d.lastTime;
+                // Debounce (Max 240 BPM)
+                if (interval > 0.25) {
+                    d.lastTime = now;
+                    d.threshold = signal * 1.2;
+
+                    // Valid interval (30 - 300 BPM)
+                    if (interval < 2.0) {
+                        d.intervals.push(interval);
+                        if (d.intervals.length > 8) d.intervals.shift();
+                        
+                        const avgInterval = d.intervals.reduce((a, b) => a + b, 0) / d.intervals.length;
+                        d.bpm = 60 / avgInterval;
+                    }
                     
-                    // Smoothly adjust beat duration
-                    state.music.beatDuration = THREE.MathUtils.lerp(state.music.beatDuration, avgInterval, 0.1);
-                    state.music.measureDuration = state.music.beatDuration * 4;
-                    state.music.bpm = Math.round(60 / state.music.beatDuration);
+                    if (i === 0) mainTrigger = true; // Bass triggers visual beat
                 }
-                
-                // Sync phase on beat
-                this.beatPhase = 0;
             }
+        });
+
+        // 3. Combine Results
+        let bpmSum = 0;
+        let weightSum = 0;
+        this.detectors.forEach(d => {
+            let bpm = d.bpm;
+            // Normalize to 90-180 range for consensus
+            if (bpm > 0) {
+                while (bpm < 90) bpm *= 2;
+                while (bpm > 180) bpm /= 2;
+                bpmSum += bpm * d.weight;
+                weightSum += d.weight;
+            }
+        });
+        
+        if (weightSum > 0) {
+            const targetBPM = bpmSum / weightSum;
+            const targetDuration = 60 / targetBPM;
+            state.music.beatDuration = THREE.MathUtils.lerp(state.music.beatDuration, targetDuration, deltaTime * 0.5);
+            state.music.measureDuration = state.music.beatDuration * 4;
+            state.music.bpm = Math.round(60 / state.music.beatDuration);
+        }
+
+        // Visuals use the Bass detector for immediate feedback
+        state.music.beatThreshold = this.detectors[0].threshold;
+        const lastBeatInterval = now - this.detectors[0].lastTime;
+        
+        if (mainTrigger) {
+            this.beatPhase = 0;
         }
 
         // --- Phase Accumulation ---