echogarden/dist/dsp/LoudnessEstimator.js

An easy-to-use speech toolset. Includes tools for synthesis, recognition, alignment, speech translation, language detection, source separation and more.

import { decibelsToGainFactor, gainFactorToDecibels } from '../audio/AudioUtilities.js';
import { SmoothEstimator } from '../utilities/SmoothEstimator.js';
import { KWeightingFilter } from './KWeightingFilter.js';
export class LoudnessEstimator {
    options;
    channelFilters = [];
    channelMeanSquares = [];
    minPower;
    constructor(options) {
        this.options = options;
        const initialMeanSquares = decibelsToGainFactor(options.initialEstimate) ** 2;
        const ticksPerSecond = this.options.sampleRate * this.options.channelCount;
        for (let i = 0; i < options.channelCount; i++) {
            const weightingFilter = new KWeightingFilter(options.sampleRate);
            const channelMeanSquares = new SmoothEstimator(options.positiveAdaptationRate / ticksPerSecond, options.negativeAdaptationRate / ticksPerSecond, initialMeanSquares);
            this.channelFilters.push(weightingFilter);
            this.channelMeanSquares.push(channelMeanSquares);
        }
        this.minPower = decibelsToGainFactor(options.minimumLoudness) ** 2;
    }
    process(sample, channel) {
        let filteredSample;
        if (this.options.applyKWeighting) {
            filteredSample = this.channelFilters[channel].process(sample);
        }
        else {
            filteredSample = sample;
        }
        const filteredSampleSquared = filteredSample ** 2;
        const channelMeanSquares = this.channelMeanSquares[channel];
        channelMeanSquares.update(filteredSampleSquared);
        channelMeanSquares.estimate = Math.max(channelMeanSquares.estimate, this.minPower);
    }
    get currentLoudness() {
        let totalMeanSquares = 0;
        for (let i = 0; i < this.options.channelCount; i++) {
            totalMeanSquares += this.channelMeanSquares[i].estimate;
        }
        const rms = Math.sqrt(totalMeanSquares / this.options.channelCount);
        const rmsDecibels = gainFactorToDecibels(rms);
        return rmsDecibels;
    }
    getCurrentRMSForChannel(channel) {
        return Math.sqrt(this.channelMeanSquares[channel].estimate);
    }
}
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