Method calculateBandEnergy

src/fl/audio/detector/frequency_bands.cpp.hpp:109–152

}

float FrequencyBands::calculateBandEnergy(const fft::Bins& fft, float minFreq, float maxFreq,
                                           float fftMinFreq, float fftMaxFreq) {
    const int numBins = static_cast<int>(fft.raw().size());
    if (numBins <= 1) {
        return 0.0f;
    }

    float totalEnergy = 0.0f;
    float totalWeight = 0.0f;

    for (int i = 0; i < numBins; i++) {
        // Compute the frequency range for this CQ bin using log-spaced
        // boundaries that match the CQ kernel's actual frequency layout.
        float binLow;
        float binHigh;
        if (i == 0) {
            binLow = fftMinFreq;
        } else {
            binLow = fft.binBoundary(i - 1);
        }
        if (i == numBins - 1) {
            binHigh = fftMaxFreq;
        } else {
            binHigh = fft.binBoundary(i);
        }

        // Calculate fractional overlap between this bin and the target band
        float overlapMin = fl::max(binLow, minFreq);
        float overlapMax = fl::min(binHigh, maxFreq);

        if (overlapMax <= overlapMin) {
            continue; // No overlap
        }

        float binWidth = binHigh - binLow;
        float overlapFraction = (overlapMax - overlapMin) / binWidth;

        totalEnergy += fft.raw()[i] * overlapFraction;
        totalWeight += overlapFraction;
    }

    // Normalize by total fractional weight to make bands comparable
    return (totalWeight > 0.0f) ? totalEnergy / totalWeight : 0.0f;
}

} // namespace detector
} // namespace audio