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Noise gate (#50)
Noise gate with quite a few tweakable settings. I set the defaults to what work best for me/my setup. - Fast attack of 1ms - Hold and release both of 50ms - Fade time of ~100-200ms - And then threshold somewhere in the middle
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‎Software/GuitarPedal/Effect-Modules/noise_gate_module.cpp‎

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#include "noise_gate_module.h"
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#include <q/fx/envelope.hpp>
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using namespace bkshepherd;
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// The threshold knob/parameter will generate a float between 0 and 1 which gets
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// multiplied by this value to be used as the threshold against the audio input
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// signal
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const float maxThreshold = 0.2;
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// These are placeholder values that will get overwritten with the attack and release parameters at initialization
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cycfi::q::ar_envelope_follower env_follower(48000.0, 0.002f, 0.020f);
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static const int s_paramCount = 5;
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static const ParameterMetaData s_metaData[s_paramCount] = {{
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name : "Threshold",
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valueType : ParameterValueType::Float,
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valueBinCount : 0,
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defaultValue : {.float_value = 0.5f},
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knobMapping : 0,
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midiCCMapping : -1
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},
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{
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name : "Atk [ms]",
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valueType : ParameterValueType::Float,
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valueBinCount : 0,
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defaultValue : {.float_value = 1.0f},
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knobMapping : 1,
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midiCCMapping : -1,
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minValue : static_cast<int>(1),
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maxValue : static_cast<int>(20)
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},
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{
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name : "Rel [ms]",
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valueType : ParameterValueType::Float,
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valueBinCount : 0,
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defaultValue : {.float_value = 50.0f},
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knobMapping : 2,
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midiCCMapping : -1,
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minValue : static_cast<int>(1),
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maxValue : static_cast<int>(500)
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},
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{
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name : "Hold [ms]",
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valueType : ParameterValueType::Float,
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valueBinCount : 0,
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defaultValue : {.float_value = 50.0f},
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knobMapping : 3,
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midiCCMapping : -1,
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minValue : static_cast<int>(0),
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maxValue : static_cast<int>(1000)
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},
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{
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name : "Fade [ms]",
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valueType : ParameterValueType::Float,
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valueBinCount : 0,
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defaultValue : {.float_value = 200.0f},
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knobMapping : 4,
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midiCCMapping : -1,
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minValue : static_cast<int>(0),
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maxValue : static_cast<int>(500)
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}};
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// Default Constructor
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NoiseGateModule::NoiseGateModule() : BaseEffectModule() {
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// Set the name of the effect
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m_name = "Noise Gate";
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// Setup the meta data reference for this Effect
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m_paramMetaData = s_metaData;
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// Initialize Parameters for this Effect
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this->InitParams(s_paramCount);
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}
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// Destructor
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NoiseGateModule::~NoiseGateModule() {
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// No Code Needed
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}
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void NoiseGateModule::Init(float sample_rate) {
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BaseEffectModule::Init(sample_rate);
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env_follower.config(GetParameterAsFloat(1) / 1000.f, GetParameterAsFloat(2) / 1000.f, sample_rate);
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}
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void NoiseGateModule::ParameterChanged(int parameter_id) {
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switch (parameter_id) {
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case 1:
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env_follower.attack(GetParameterAsFloat(1) / 1000.f, GetSampleRate());
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break;
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case 2:
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env_follower.release(GetParameterAsFloat(2) / 1000.f, GetSampleRate());
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break;
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}
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}
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void NoiseGateModule::ProcessMono(float in) {
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// Update envelope follower with input signal
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const float raw_env_level = env_follower(std::abs(in));
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// Run a smoothing filter on the envelope to prevent crackling due to rapid adjustments of the envelope state
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const float currentTimeInSeconds = static_cast<float>(daisy::System::GetNow()) / 1000.f;
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const float smoothed_env_level = m_smoothingFilter(raw_env_level, currentTimeInSeconds);
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if (smoothed_env_level > GetParameterAsFloat(0) * maxThreshold) {
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// Signal is above the threshold, open the gate and reset the timer
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m_gateOpen = true;
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m_holdTimer = 0.0f;
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m_currentGain = 1.0f; // Fully open
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} else if (m_gateOpen) {
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// Signal is below the threshold but within hold time
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const float dt = currentTimeInSeconds - m_prevTimeSeconds;
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m_holdTimer += dt;
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if (m_holdTimer >= (GetParameterAsFloat(3) / 1000.0f)) {
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// Gate is closing: start fading out
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const float fadeOutStep = dt / (GetParameterAsFloat(4) / 1000.0f);
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m_currentGain -= fadeOutStep;
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if (m_currentGain <= 0.0f) {
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m_currentGain = 0.0f;
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m_gateOpen = false;
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}
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}
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}
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m_prevTimeSeconds = currentTimeInSeconds;
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// Apply noise gate using the smoothed envelope value and hold time, and
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// also the current gain value (used for fade)
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const float out = m_gateOpen ? in * m_currentGain : 0.0f;
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m_audioLeft = out;
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m_audioRight = m_audioLeft;
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}
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void NoiseGateModule::ProcessStereo(float inL, float inR) {
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// Calculate the mono effect
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ProcessMono(inL);
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}
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float NoiseGateModule::GetBrightnessForLED(int led_id) const {
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float value = BaseEffectModule::GetBrightnessForLED(led_id);
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if (led_id == 1) {
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return m_gateOpen ? 1.0f : 0.0f;
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}
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return value;
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}

‎Software/GuitarPedal/Effect-Modules/noise_gate_module.h‎

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#pragma once
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#ifndef NOISEGATE_MODULE_H
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#define NOISEGATE_MODULE_H
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#include <stdint.h>
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#include "../Util/1efilter.hpp"
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#include "base_effect_module.h"
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#ifdef __cplusplus
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/** @file noisegate_module.h */
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namespace bkshepherd {
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class NoiseGateModule : public BaseEffectModule {
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public:
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NoiseGateModule();
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~NoiseGateModule();
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void Init(float sample_rate) override;
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void ParameterChanged(int parameter_id) override;
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void ProcessMono(float in) override;
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void ProcessStereo(float inL, float inR) override;
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float GetBrightnessForLED(int led_id) const override;
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private:
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// inputs:
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// estimated frequency: overwritten by timestamps at runtime and not used
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// cutoff freq
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// beta: 0.0f disables it entirely, but used for scaling cutoff frequency
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// derivative cutoff freq: used when beta is > 0
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one_euro_filter<float, float> m_smoothingFilter{48000, 0.5f, 0.05f, 1.0f};
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float m_holdTimer; // Timer tracking hold duration
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bool m_gateOpen; // Is the gate currently open?
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float m_prevTimeSeconds;
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float m_currentGain;
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};
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} // namespace bkshepherd
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#endif
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#endif

‎Software/GuitarPedal/guitar_pedal.cpp‎

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#include "Effect-Modules/looper_module.h"
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#include "Effect-Modules/metro_module.h"
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#include "Effect-Modules/multi_delay_module.h"
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#include "Effect-Modules/noise_gate_module.h"
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#include "Effect-Modules/overdrive_module.h"
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#include "Effect-Modules/peq_module.h"
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#include "Effect-Modules/pitch_shifter_module.h"
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crossFaderTransitionTimeInSamples = hardware.GetNumberOfSamplesForTime(crossFaderTransitionTimeInSeconds);
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// Init the Effects Modules
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availableEffectsCount = 14;
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availableEffectsCount = 15;
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availableEffects = new BaseEffectModule *[availableEffectsCount];
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availableEffects[0] = new ModulatedTremoloModule();
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availableEffects[1] = new OverdriveModule();
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availableEffects[11] = new LooperModule();
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availableEffects[12] = new GraphicEQModule();
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availableEffects[13] = new ParametricEQModule();
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availableEffects[14] = new NoiseGateModule();
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for (int i = 0; i < availableEffectsCount; i++) {
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availableEffects[i]->Init(sample_rate);

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