calculateCompression.js

export function calculateCompression(audioData){

    // Convert the linear values to dB
    let audioDataInDb = audioData.map(x => -20 * Math.log10(x || 1e-9)); // Avoid log(0) by replacing 0 with a very small number

    // Compute the peak value
    let peak = Math.max(...audioDataInDb);

    // Compute the RMS value
    let sumOfSquares = 0;
    for (let i = 0; i < audioDataInDb.length; i++) {
        sumOfSquares += audioDataInDb[i] * audioDataInDb[i];
    }
    let rms = Math.sqrt(sumOfSquares / audioDataInDb.length);

    // Calculate the difference between the peak and the RMS level
    let compression = peak - rms;

    return compression;
}

calculateSNR.js

export function calculateSNR(audioData){

    // Convert the linear values to dB
    let ad = audioData.filter(x => (x>=0));
    let audioDataInDb = ad.map(x => -20 * Math.log10(x || 1e-9)); // Avoid log(0) by replacing 0 with a very small number

    // Compute the mean value (signal power)
    let signalPower = 0;
    for (let i = 0; i < audioDataInDb.length; i++) {
        signalPower += audioDataInDb[i] * audioDataInDb[i];
    }
    signalPower /= audioDataInDb.length;

    // Compute the variance (noise power)
    let noisePower = 0;
    let mean = signalPower / audioDataInDb.length;
    for (let i = 0; i < audioDataInDb.length; i++) {
        noisePower += Math.pow(audioDataInDb[i] - mean, 2);
    }
    noisePower /= audioDataInDb.length;

    // Make sure we don't divide by zero
    if (noisePower === 0) {
        return Infinity;
    }

    // Compute the SNR in decibels
    let snrDb = 10 * Math.log10(signalPower / noisePower);
    return snrDb;
}