feat: true RMS dBFS level measurement for LevelMeterFab via getFloatTimeDomainData

DeepDrftPublic/Interop/audio/SpectrumAnalyzer.ts

@@ -16,6 +16,7 @@ export class SpectrumAnalyzer {
     private audioContext: AudioContext | null = null;
     private fftSize: number = 2048;
     private dataArray: Float32Array<ArrayBuffer> | null = null;
+    private timeDomainArray: Float32Array<ArrayBuffer> | null = null;
 
     // Configuration
     private bucketCount: number = 32;
@@ -26,6 +27,7 @@ export class SpectrumAnalyzer {
     // Animation state - supports multiple callbacks per player
     private animationId: number | null = null;
     private callbacks = new Map<string, (data: number[]) => void>();
+    private levelCallbacks = new Map<string, (db: number) => void>();
     private lastFrameTime: number = 0;
     private targetFrameInterval: number = 1000 / 30; // ~30fps for smooth visuals without excessive interop
 
@@ -35,6 +37,7 @@ export class SpectrumAnalyzer {
         this.analyser.fftSize = this.fftSize;
         this.analyser.smoothingTimeConstant = 0.8;
         this.dataArray = new Float32Array(this.analyser.frequencyBinCount);
+        this.timeDomainArray = new Float32Array(this.analyser.fftSize);
 
         return this.analyser;
     }
@@ -121,6 +124,22 @@ export class SpectrumAnalyzer {
         return buckets;
     }
 
+    /**
+     * Get the true RMS signal level in dBFS from the time-domain waveform.
+     * Unlike getFrequencyData (FFT peaks), this reflects the actual signal level
+     * and calibrates against commercial loudness targets. Returns -Infinity on silence.
+     */
+    getLevelDb(): number {
+        if (!this.analyser || !this.timeDomainArray) return -Infinity;
+        this.analyser.getFloatTimeDomainData(this.timeDomainArray);
+        let sum = 0;
+        for (let i = 0; i < this.timeDomainArray.length; i++) {
+            sum += this.timeDomainArray[i] * this.timeDomainArray[i];
+        }
+        const rms = Math.sqrt(sum / this.timeDomainArray.length);
+        return rms > 0 ? 20 * Math.log10(rms) : -Infinity;
+    }
+
     /**
      * Apply high-pass, low-pass, and slope correction filters
      */
@@ -157,7 +176,7 @@ export class SpectrumAnalyzer {
      * Add a callback for spectrum data. Starts animation loop on first subscriber.
      */
     addCallback(id: string, callback: (data: number[]) => void): void {
-        const wasEmpty = this.callbacks.size === 0;
+        const wasEmpty = this.callbacks.size === 0 && this.levelCallbacks.size === 0;
         this.callbacks.set(id, callback);
         if (wasEmpty) {
             this.lastFrameTime = 0;
@@ -170,7 +189,30 @@ export class SpectrumAnalyzer {
      */
     removeCallback(id: string): void {
         this.callbacks.delete(id);
-        if (this.callbacks.size === 0) {
+        if (this.callbacks.size === 0 && this.levelCallbacks.size === 0) {
+            this.stopAnimation();
+        }
+    }
+
+    /**
+     * Add a callback for true RMS level data (dBFS). Shares the spectrum animation
+     * loop; starts it only if both callback maps were previously empty.
+     */
+    addLevelCallback(id: string, callback: (db: number) => void): void {
+        const wasEmpty = this.callbacks.size === 0 && this.levelCallbacks.size === 0;
+        this.levelCallbacks.set(id, callback);
+        if (wasEmpty) {
+            this.lastFrameTime = 0;
+            this.animationId = requestAnimationFrame(this.animate);
+        }
+    }
+
+    /**
+     * Remove a level callback by ID. Stops the shared loop only when both maps are empty.
+     */
+    removeLevelCallback(id: string): void {
+        this.levelCallbacks.delete(id);
+        if (this.callbacks.size === 0 && this.levelCallbacks.size === 0) {
             this.stopAnimation();
         }
     }
@@ -186,16 +228,21 @@ export class SpectrumAnalyzer {
     }
 
     private animate = (timestamp: number): void => {
-        if (this.callbacks.size === 0) return;
+        if (this.callbacks.size === 0 && this.levelCallbacks.size === 0) return;
 
         // Throttle to target frame rate
         const elapsed = timestamp - this.lastFrameTime;
         if (elapsed >= this.targetFrameInterval) {
             this.lastFrameTime = timestamp - (elapsed % this.targetFrameInterval);
-            const data = this.getFrequencyData();
-            // Broadcast to all callbacks
-            for (const cb of this.callbacks.values()) {
-                cb(data);
+
+            if (this.callbacks.size > 0) {
+                const data = this.getFrequencyData();
+                for (const cb of this.callbacks.values()) cb(data);
+            }
+
+            if (this.levelCallbacks.size > 0) {
+                const db = this.getLevelDb();
+                for (const cb of this.levelCallbacks.values()) cb(db);
             }
         }
 
@@ -205,8 +252,10 @@ export class SpectrumAnalyzer {
     dispose(): void {
         this.stopAnimation();
         this.callbacks.clear();
+        this.levelCallbacks.clear();
         this.analyser = null;
         this.audioContext = null;
         this.dataArray = null;
+        this.timeDomainArray = null;
     }
 }