42 lines
1.1 KiB
C++
42 lines
1.1 KiB
C++
#pragma once
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#include "stdafx.h"
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#include <assert.h>
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#include <numeric>
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class LowPassFilter
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{
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private:
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uint8_t _prevSampleCounter = 0;
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int16_t _prevSamplesLeft[10] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
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int16_t _prevSamplesRight[10] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
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void UpdateSample(int16_t* buffer, size_t index, int strength, double volume, int16_t* _prevSamples)
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{
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if (strength > 0)
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{
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int32_t sum = std::accumulate(_prevSamples, _prevSamples + strength, 0);
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buffer[index] = (int16_t)((sum + buffer[index]) / (strength + 1) * volume);
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_prevSamples[_prevSampleCounter] = buffer[index];
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}
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else
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{
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buffer[index] = (int16_t)(buffer[index] * volume);
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}
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}
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public:
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void ApplyFilter(int16_t* buffer, size_t sampleCount, int strength, double volume = 1.0f)
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{
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assert(strength <= 10);
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for (size_t i = 0; i < sampleCount * 2; i += 2)
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{
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UpdateSample(buffer, i, strength, volume, _prevSamplesLeft);
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UpdateSample(buffer, i + 1, strength, volume, _prevSamplesRight);
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if (strength > 0)
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{
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_prevSampleCounter = (_prevSampleCounter + 1) % strength;
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}
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}
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}
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};
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