ERB_FFTSpectrogram.h

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//=====================================================================================
//=====================================================================================
 
#pragma once
using CoefficientsIIR = juce::dsp::IIR::Coefficients<float>;
using CoefficientsFIR = juce::dsp::FIR::Coefficients<float>;
 
namespace krotos
{
    //==============================================================================
    class ERB_FFTSpectrogram
    {
      public:
        ERB_FFTSpectrogram();
 
        void setSampleRate(float fs);
 
        std::vector<std::vector<float>> filterSpectrum(std::vector<float>& inputSignal);
 
        void drawSpectrogram(juce::Image& image, const std::vector<std::vector<float>>& erbSTFTPowMatrix);
 
        std::vector<float> getERBSpace() { return m_cfArray; };
 
        static std::vector<float> erbs2Hz(const std::vector<float>& erbsVector);
        static Eigen::VectorXf erbs2Hz(const Eigen::VectorXf& erbsVector);
 
        static std::vector<float> hz2Erbs(const std::vector<float>& hzVector);
        static Eigen::VectorXf hz2Erbs(const Eigen::VectorXf& hzVector);
        static float hz2Erbs(const float hz);
 
      private:
        std::vector<float> applyEarFilter(std::vector<float>& inputSignal);
 
        std::vector<float> gtWindow(int numberOfPoints, float bParam, int order);
 
        /* Cambridge equivalent rectangular bandwidth at cf - from Hartmann (1997)
         *  @param cf       Hz - characteristic frequency(multiple versions for
         * float/double and vector)
         *  @returns    equivalent rectangular bandwidth at cf
         */
        std::vector<float> cferb(std::vector<float> cf);
        float cferb(const float cf);
        double cferb(const double cf);
 
        std::vector<float> erbSpace(float low, float hi, int N);
 
        float centroid(const std::vector<float>& x);
 
        float getNextPowerOfTwo(float value);
 
        void buildFilterBank(int startSamplesSize);
 
        std::vector<std::vector<float>> calculatePowerSpectrum(const std::vector<std::vector<float>>& inFrames);
 
        //----------------------------------------------- Private members
        //---------------------------------------------------
        float m_sampleRate{-1.0f};
        std::vector<std::vector<double>> m_wfunct;
        // zero pad signal
        std::vector<float> m_cfArray;
 
        EarFilter m_earFilter;
 
        // hopSize in seconds
        float m_hopSizeSec = 0.0058f;
        int m_hopSizeSamples;
 
        const float m_exponent = 0.25f;
 
        // Parameters for the spectrogram matrix
        // lowest cf
        float m_lo = 30.0f;
        // upper cf
        float m_hi = 16000.0f;
        // number of channles
        int m_numChans = 77;
 
        /*  Window size and shape are based on the envelope of the gammatone
         *   impulse response of the lowest CF channel, with ERB = 24.7 Hz.
         *  The FFT window size is the smallest power of 2 larger than twice the
         *  ERD of this window.
         */
        float m_bw0 = 24.7f;       // Hz - base frequency of ERB formula(= bandwidth of "0Hz" channel)
        float m_b0 = 25.15274949f; // gammatone b parameter(Hartmann, 1997)
        float m_ERD = 0.0196797f;  // based on numerical calculation of ERD
        int m_wSize;
        std::vector<float> m_gtWin; // gammatone window
 
        // scaling constant for spectrogram y frequency scaling
        const float m_scalingConstant = 0.1f;
        int m_fftSize;
 
        void writeMatrixToFile(const std::vector<std::vector<float>>& matrix, const std::string& filename)
        {
            std::ofstream outputFile(filename);
            if (!outputFile.is_open())
            {
                DBG("Failed to open file: ");
                return;
            }
 
            for (const auto& row : matrix)
            {
                for (const auto& value : row)
                {
                    outputFile << value << " ";
                }
                outputFile << '\n';
            }
 
            outputFile.close();
        }
    };
} // namespace krotos