calculateVocalPresenceRatio()

float fl::audio::detector::Vocal::calculateVocalPresenceRatio ( const fft::Bins & broadFft )

private

Definition at line 246 of file vocal.cpp.hpp.

                                                           {
    // Vocal presence ratio using LINEAR bins for better high-frequency resolution.
    // CQ bins compress the presence band (2-4 kHz) into few bins; linear bins
    // give uniform frequency resolution across the spectrum.
    //
    // Ratio = mean energy in 2-4 kHz (F3 formant / sibilance) /
    //         mean energy in 80-400 Hz (guitar fundamentals / bass)
    // Voice adds energy in the 2-4 kHz range; guitar energy decays above 2 kHz.
    auto linearBins = fft.linear();
    if (linearBins.size() < 4) return 0.0f;
 
    const int numBins = static_cast<int>(linearBins.size());
    const float fmin = fft.linearFmin();
    const float fmax = fft.linearFmax();
    const float binWidth = (fmax - fmin) / static_cast<float>(numBins);
 
    // Map frequency to linear bin index
    auto freqToLinBin = [&](float freq) -> int {
        if (freq <= fmin) return 0;
        if (freq >= fmax) return numBins - 1;
        return fl::min(numBins - 1, static_cast<int>((freq - fmin) / binWidth));
    };
 
    const int presMinBin = freqToLinBin(2000.0f);
    const int presMaxBin = freqToLinBin(4000.0f);
    const int bassMinBin = freqToLinBin(200.0f);
    const int bassMaxBin = freqToLinBin(500.0f);
 
    float presEnergy = 0.0f;
    int presCount = 0;
    for (int i = presMinBin; i <= presMaxBin && i < numBins; ++i) {
        presEnergy += linearBins[i] * linearBins[i];
        ++presCount;
    }
    if (presCount > 0) presEnergy /= static_cast<float>(presCount);
 
    float bassEnergy = 0.0f;
    int bassCount = 0;
    for (int i = bassMinBin; i <= bassMaxBin && i < numBins; ++i) {
        bassEnergy += linearBins[i] * linearBins[i];
        ++bassCount;
    }
    if (bassCount > 0) bassEnergy /= static_cast<float>(bassCount);
 
    if (bassEnergy < 1e-12f) return 0.0f;
    return presEnergy / bassEnergy;
}

References fl::min().

Referenced by update().

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