murmuraba/dist/vad/algorithms/energy-vad.js

Real-time audio noise reduction with advanced chunked processing for web applications

/**
 * Energy-based Voice Activity Detection
 */
export class EnergyVAD {
    constructor() {
        this.noiseFloor = 0;
        this.adaptiveThreshold = 0.01;
        this.smoothingFactor = 0.95;
    }
    /**
     * Calculate RMS energy of audio frame
     */
    calculateEnergy(frame) {
        let sum = 0;
        for (let i = 0; i < frame.length; i++) {
            sum += frame[i] * frame[i];
        }
        return Math.sqrt(sum / frame.length);
    }
    /**
     * Update noise floor estimate
     */
    updateNoiseFloor(energy, isSpeech) {
        if (!isSpeech) {
            // Update noise floor with exponential averaging
            this.noiseFloor = this.smoothingFactor * this.noiseFloor +
                (1 - this.smoothingFactor) * energy;
            // Update adaptive threshold
            this.adaptiveThreshold = Math.max(0.01, this.noiseFloor * 3);
        }
    }
    /**
     * Detect voice activity based on energy
     */
    detect(frame) {
        const energy = this.calculateEnergy(frame);
        // Simple thresholding with adaptive component
        const threshold = Math.max(this.adaptiveThreshold, 0.01);
        const vadScore = Math.min(1, energy / threshold);
        // Update noise floor if likely non-speech
        if (vadScore < 0.5) {
            this.updateNoiseFloor(energy, false);
        }
        return vadScore;
    }
    /**
     * Calculate energy metrics for a frame
     */
    getMetrics(frame) {
        const energy = this.calculateEnergy(frame);
        return {
            energy,
            noiseFloor: this.noiseFloor,
            threshold: this.adaptiveThreshold
        };
    }
    /**
     * Reset the detector state
     */
    reset() {
        this.noiseFloor = 0;
        this.adaptiveThreshold = 0.01;
    }
}