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#pragma once
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#define _USE_MATH_DEFINES
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#include <cmath>
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namespace ReverbHallRoom
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{
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class Lp1
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{
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private:
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float fs;
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float b0, a1;
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float cutoffHz;
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public:
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float Output;
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Lp1()
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{
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fs = 48000;
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b0 = 1;
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a1 = 0;
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cutoffHz = 1000;
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}
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float GetSamplerate()
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{
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return fs;
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}
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void SetSamplerate(float samplerate)
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{
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fs = samplerate;
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}
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float GetCutoffHz()
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{
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return cutoffHz;
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}
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void SetCutoffHz(float hz)
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{
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cutoffHz = hz;
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Update();
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}
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void ClearBuffers()
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{
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Output = 0;
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}
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void Update()
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{
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// Prevent going over the Nyquist frequency
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if (cutoffHz >= fs * 0.5f)
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cutoffHz = fs * 0.499f;
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auto x = 2.0f * M_PI * cutoffHz / fs;
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auto nn = (2.0f - cosf(x));
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auto alpha = nn - sqrtf(nn * nn - 1);
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a1 = alpha;
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b0 = 1 - alpha;
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}
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float Process(float input)
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{
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if (input == 0 && Output < 0.0000001f)
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{
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Output = 0;
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}
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else
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{
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Output = b0 * input + a1 * Output;
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}
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return Output;
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}
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void Process(float* input, float* output, int len)
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{
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for (int i = 0; i < len; i++)
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output[i] = Process(input[i]);
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}
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};
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}
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