NoiseGate.h File Reference

Noise gate with hysteresis, hold time, and duck mode. More...

#include "../Core/DspMath.h"
#include "../Core/AudioSpec.h"
#include "../Core/AudioBuffer.h"
#include "../Core/DenormalGuard.h"
#include "../Core/StateBlob.h"
#include <algorithm>
#include <array>
#include <atomic>
#include <cmath>
#include <cstddef>
#include <cstdint>
#include <numbers>
#include <utility>
#include <vector>

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Classes
class	dspark::NoiseGate< T >
	High-performance noise gate with state machine, hysteresis, and zero-allocation processing. More...

Namespaces
namespace	dspark
	Main namespace for the DSPark framework.

Detailed Description

Noise gate with hysteresis, hold time, and duck mode.

A professional noise gate that attenuates audio below a threshold. Uses a state machine (Open/Hold/Close) with hysteresis to prevent chattering. Includes an internal peak envelope detector for distortion-free low-frequency tracking. Thresholds are precomputed in the linear domain, so the per-sample path is branch-light and free of log/pow calls (the envelope recursion itself is serial and does not vectorize).

Features:

• State machine: Open -> Hold -> Close (with hysteresis)
• True envelope peak detection (prevents audio-rate chatter)
• Open/close threshold hysteresis
• Configurable hold time before closing
• Range: -inf to 0 dB (allows partial attenuation)
• Sidechain: internal or external with optional HPF
• Duck mode (attenuate when above threshold, for ducking music under voice)
• Stereo linked detection
• Smooth attack/release transitions
• Adaptive hold (holds at least one estimated signal period)

Threading: prepare() belongs to the setup thread; processBlock(), processSample() and reset() belong to the audio thread. All setters are lock-free atomic publications, safe from any thread; they are consumed at the start of the next block (or the next processSample() call). Non-finite setter arguments are ignored.

Dependencies: DspMath.h, AudioSpec.h, AudioBuffer.h, DenormalGuard.h, StateBlob.h.

dspark::NoiseGate<float> gate;
gate.prepare(48000.0);
gate.setThreshold(-40.0f);  // open at -40 dB
gate.setHysteresis(4.0f);   // close at -44 dB
gate.setAttack(0.5f);       // 0.5 ms attack
gate.setHold(50.0f);        // 50 ms hold
gate.setRelease(100.0f);    // 100 ms release
 
for (int i = 0; i < numSamples; ++i)
    output[i] = gate.processSample(input[i]);

Definition in file NoiseGate.h.