soothe2-re/dsp/detect.cpp

#include "detect.hpp"
#include <cmath>

Detector::Detector() : sharpness_(10), selectivity_(10), depth_(0.864) {
}

void Detector::setParams(float sharpness, float selectivity, float depth) {
    sharpness_ = sharpness;
    selectivity_ = selectivity;
    depth_ = depth;
}

float Detector::computeReduction(float magnitude, float freq) {
    float level_db = 20 * std::log10(std::max(magnitude, 1e-12f));
    float base_red = std::min(std::max(level_db + 10, 0.0f), 60.0f);
    float amount = base_red * depth_;
    return std::min(amount, 60.0f);
}

size_t Detector::detectPeaks(const std::complex<double>* spectrum, size_t n,
                             float sample_rate, Peak* peaks, size_t max_peaks) {
    float spacing_bins = std::max(2.0f, selectivity_ * 0.5f);
    
    size_t count = 0;
    for (size_t k = 1; k < n - 1; k++) {
        double mag = std::abs(spectrum[k]);
        double mag_prev = std::abs(spectrum[k - 1]);
        double mag_next = std::abs(spectrum[k + 1]);
        
        if (mag > mag_prev && mag > mag_next) {
            float freq = k * sample_rate / (2 * n);
            float red = computeReduction(static_cast<float>(mag), freq);
            
            if (red > 3.0f) {
                bool is_peak = true;
                for (size_t i = 0; i < count; i++) {
                    if (std::abs(peaks[i].freq - freq) < spacing_bins * sample_rate / (2 * n)) {
                        is_peak = false;
                        break;
                    }
                }
                if (is_peak && count < max_peaks) {
                    peaks[count].bin = k;
                    peaks[count].freq = freq;
                    peaks[count].magnitude = static_cast<float>(mag);
                    peaks[count].reduction = red;
                    count++;
                }
            }
        }
    }
    return count;
}