132 lines
3.5 KiB
C++
132 lines
3.5 KiB
C++
/*
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* oversampler.h
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* Copyright (c) 2025 Christopher Herb
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#pragma once
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#include <array>
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#include <vector>
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#include "../filter/chebyshev.h"
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namespace trnr {
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template <typename sample>
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class oversampler {
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public:
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oversampler()
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{
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buffer[0].reserve(num_samples);
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buffer[1].reserve(num_samples);
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}
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~oversampler() { delete[] ptrs; }
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void init(double _samplerate, int _ratio)
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{
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samplerate = _samplerate * _ratio;
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filter_freq = _samplerate * 0.5 - 4000;
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lowpass_in1.reset(samplerate, filter_freq);
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lowpass_in2.reset(samplerate, filter_freq);
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lowpass_out1.reset(samplerate, filter_freq);
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lowpass_out2.reset(samplerate, filter_freq);
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ratio = _ratio;
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}
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sample** upsample(sample** _inputs, int _blocksize)
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{
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num_samples = _blocksize;
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required_blocksize = _blocksize * ratio;
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if (required_blocksize > current_blocksize) {
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// resize buffer
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buffer[0].resize(required_blocksize);
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buffer[1].resize(required_blocksize);
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current_blocksize = required_blocksize;
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}
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for (int i = 0; i < _blocksize; ++i) {
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const int adjusted_index = i * ratio;
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buffer[0][adjusted_index] = _inputs[0][i];
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buffer[1][adjusted_index] = _inputs[1][i];
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for (int j = 1; j < ratio; ++j) {
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buffer[0][adjusted_index + j] = 0.0f;
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buffer[1][adjusted_index + j] = 0.0f;
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}
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}
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if (ratio > 1) {
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lowpass_in1.process_block(buffer[0].data(), required_blocksize);
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lowpass_in2.process_block(buffer[1].data(), required_blocksize);
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// compensate volume loss
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for (int i = 0; i < required_blocksize; ++i) {
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buffer[0][i] *= ratio;
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buffer[1][i] *= ratio;
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}
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}
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ptrs[0] = buffer[0].data();
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ptrs[1] = buffer[1].data();
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return ptrs;
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}
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void downsample(sample** _outputs)
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{
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if (ratio > 1) {
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lowpass_out1.process_block(buffer[0].data(), required_blocksize);
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lowpass_out2.process_block(buffer[1].data(), required_blocksize);
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}
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for (int i = 0; i < num_samples; ++i) {
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_outputs[0][i] = buffer[0][i * ratio];
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_outputs[1][i] = buffer[1][i * ratio];
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}
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}
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private:
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int ratio = 1;
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double samplerate = 48000;
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int num_samples = 256;
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float filter_freq = 20000.f;
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int current_blocksize = num_samples;
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int required_blocksize = num_samples;
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chebyshev lowpass_in1 {samplerate, 20000};
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chebyshev lowpass_in2 {samplerate, 20000};
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chebyshev lowpass_out1 {samplerate, 20000};
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chebyshev lowpass_out2 {samplerate, 20000};
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std::array<std::vector<sample>, 2> buffer;
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sample** ptrs = new sample*[2];
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};
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} // namespace trnr
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