ShortTimeFourierTransform.h

Go to the documentation of this file.

namespace krotos
{
    //==============================================================================
    class ShortTimeFourierTransform
    {
      public:
        enum fftMode
        {
            freqMagOnly = 0,
            realOnly,
            complex,
            modeNUM_MODES
        } m_mode;
 
        enum class FrequencyRange
        {
            Whole,
            Half,
            // TODO: Add more in the future if necessary
        };
 
        struct DFTParams
        {
            // TODO:: Check to convert to const
            int winSize;
            int fftSize;
            int hopSize;
            int nOverlap;
            int sampleRate;
            // TODO:: Rename to m_ after stl removal
            Eigen::VectorXf window;
        } dftParams;
 
        ShortTimeFourierTransform(int winSizeSamples, int fftSizeSamples, int hopSize, WindowType winMethod,
                                  fftMode mode, int sampleRate);
 
        std::vector<std::vector<float>> stft(const AudioSampleBuffer& inputSignal);
        Eigen::MatrixXf processSignal(const Eigen::VectorXf inputSignal);
 
        std::vector<float> istft(std::vector<std::vector<float>> stftMatrix);
 
        void drawSpectrogram(juce::Image& image, const std::vector<std::vector<float>>& stftMatrix);
 
        // TODO::stl removal- there is copy of data happening here !!!!
        std::vector<float> getBinsSTL(ShortTimeFourierTransform::FrequencyRange freqRange);
        Eigen::VectorXf getBins(ShortTimeFourierTransform::FrequencyRange freqRange);
 
        // TODO::stl removal- there is copy of data happening here !!!!
        std::vector<float> getColumnsSTL();
        Eigen::VectorXf getColumns();
 
        float getFFTBinSize() const;
 
      private:
        struct BinParams
        {
            bool isNPTSodd;
            int halfNPTS{-1};
            bool isHalfNPTSodd;
            int quarterNPTS{-1};
            float binSize{-1.0f};
        } binParams;
 
        void NPTSinfo(float NPTS);
        Eigen::VectorXf finalGrid(const Eigen::VectorXf& w1, float Nyq, bool centerDC,
                                  ShortTimeFourierTransform::FrequencyRange freqRange);
 
        // the fft Object
        juce::dsp::FFT m_fft;
        // Window function
        std::vector<float> m_window;
 
        // used in stft
        std::vector<float> m_sigFrame;
        // TODO:: Rename to m_ after stl removal
        Eigen::VectorXf sigFrame;
 
        // number of total frames, needed for spectrogram
        int m_numFrames{0};
 
        // scaling constant for spectrogram y frequency scaling
        const float m_scalingConstant = 0.1f;
 
        int m_inputSize{0};
    };
} // namespace krotos