Line data    Source code

       1              : #include "audio/effects/dynamics/noise_gate.h"
       2              : 
       3              : #include "audio/effects/core/effect_factory.h"
       4              : 
       5              : namespace Amplitron {
       6              : 
       7            2 : static EffectRegistrar<NoiseGate> reg("Noise Gate");
       8              : 
       9          120 : NoiseGate::NoiseGate() {
      10          270 :     params_ = {
      11           90 :         {"Threshold", -55.0f, -80.0f, 0.0f, -55.0f, "dB",
      12           30 :          "Signal level below which the gate closes and mutes the audio. Set just above background "
      13              :          "noise level."},
      14           30 :         {"Attack", 0.5f, 0.1f, 10.0f, 0.5f, "ms",
      15           30 :          "How quickly the gate opens when the signal exceeds the threshold. Fast attack preserves "
      16              :          "pick transients."},
      17           30 :         {"Release", 50.0f, 5.0f, 500.0f, 50.0f, "ms",
      18           30 :          "How quickly the gate closes after the signal falls below threshold. Longer release "
      19              :          "preserves sustained notes."},
      20          270 :     };
      21          180 : }
      22              : 
      23           87 : void NoiseGate::process(float* buffer, int num_samples) {
      24           87 :     if (!enabled_) return;
      25              : 
      26           87 :     float threshold = db_to_linear(params_[0].value);
      27           87 :     float attack_coeff = EnvelopeFollower::time_to_coeff(params_[1].value, sample_rate_);
      28           87 :     float release_coeff = EnvelopeFollower::time_to_coeff(params_[2].value, sample_rate_);
      29              : 
      30        21015 :     for (int i = 0; i < num_samples; ++i) {
      31        20928 :         float envelope = env_.process(buffer[i], attack_coeff, release_coeff);
      32              : 
      33        20928 :         float target_gain = (envelope > threshold) ? 1.0f : 0.0f;
      34        20928 :         float gain_coeff = (target_gain > gain_) ? attack_coeff : release_coeff;
      35        20928 :         gain_ += (target_gain - gain_) * (1.0f - gain_coeff);
      36        20928 :         buffer[i] *= gain_;
      37         6976 :     }
      38           29 : }
      39              : 
      40           78 : void NoiseGate::reset() {
      41           78 :     env_.reset();
      42           78 :     gain_ = 0.0f;
      43           78 : }
      44              : 
      45              : }  // namespace Amplitron