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/*
* Copyright (c) 2020-2021 Vasile Vilvoiu <vasi.vilvoiu@gmail.com>
*
* specgram is free software; you can redistribute it and/or modify
* it under the terms of the MIT license. See LICENSE for details.
*/
#ifndef _FFT_HPP_
#define _FFT_HPP_
#include "window-function.hpp"
#include <fftw3.h>
class FFT {
private:
/* FFT window width */
const std::size_t window_width_;
/* fftw buffers */
fftw_complex *in_;
fftw_complex *out_;
/* fftw plan */
fftw_plan plan_;
/* window function */
std::unique_ptr<WindowFunction> window_function_;
public:
FFT() = delete;
FFT(const FFT &c) = delete;
FFT(FFT &&) = delete;
FFT & operator=(const FFT&) = delete;
FFT(std::size_t win_width, std::unique_ptr<WindowFunction>& win_func);
virtual ~FFT();
ComplexWindow Compute(const ComplexWindow& input);
static RealWindow GetMagnitude(const ComplexWindow& input, bool alias);
static std::tuple<double, double> GetFrequencyLimits(double rate, std::size_t width);
static double GetFrequencyIndex(double rate, std::size_t width, double f);
static RealWindow Resample(const RealWindow& input, double rate, std::size_t width, double fmin, double fmax);
static RealWindow Crop(const RealWindow& input, double rate, double fmin, double fmax);
};
#endif
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