86 lines
2.2 KiB
C++
86 lines
2.2 KiB
C++
/**
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* @file sampling.h
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* @author 9exa
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* @brief Objects that resamples signal frames
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* @version 0.1
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* @date 2023-05-08
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*
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* @copyright Copyright (c) 2023
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*
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*/
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#ifndef MENGA_SAMPLING
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#define MENGA_SAMPLING
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#include "miniaudio.h"
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#include "mengumath.h"
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#include "common.h"
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#include <cstdint>
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#include <vector>
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namespace Mengu {
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namespace dsp {
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// Performs linear resampling without any filtering. Useful for resampling frequency domain directly
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template<class T>
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inline void linear_resample_no_filter(const T *input,
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T *output,
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uint32_t size,
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float shift_factor,
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T interp(T a, T b, float w) = &lerp,
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T def_val = T()) {
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float shift_rep = 1 / shift_factor;
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// interpelate the positiobs in the input
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if (shift_factor > 1.0f) {
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// iterate from the back of the array to make the resample work in-place
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for (uint32_t j = 0; j < size; j++) {
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float inp_index = j * shift_rep;
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uint32_t lower = uint32_t(inp_index);
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float remainder = inp_index - lower;
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output[j] = interp(input[lower], input[lower + 1], remainder);
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}
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}
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else {
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int j = size - 1;
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int resample_start = (int) (size * shift_factor);
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while (j >= resample_start) {
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output[j] = def_val;
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j -= 1;
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}
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while (j >= 0) {
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int inp_index = j * shift_rep;
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int lower = int(inp_index);
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float remainder = inp_index - lower;
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output[j] = interp(input[lower], input[lower + 1], remainder);
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j -= 1;
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}
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}
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}
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// Just a wrapper around miniaudios resampler API, which uses linear resampling
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// with a 4th order lowpass filter by default
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class LinearResampler {
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public:
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LinearResampler(uint32_t nchannels, float stretch_factor);
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~LinearResampler();
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void set_stretch_factor(float stretch_factor);
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std::vector<Complex> resample(const std::vector<Complex> &samples);
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private:
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ma_linear_resampler _resampler;
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float _stretch_factor;
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uint32_t _nchannels;
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};
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}
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}
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#endif
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