Line data    Source code

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