Line data    Source code

       1              : #pragma once
       2              : 
       3              : // Algorithmic reverb for adding room and tail reflections.
       4              : // Uses a Schroeder-style network: parallel feedback combs y_i[n]=x[n]+g_i*y_i[n-d_i]
       5              : // build the decay tail, followed by all-pass filters that diffuse echoes while
       6              : // keeping magnitude roughly flat.
       7              : 
       8              : #include "audio/effects/effect.h"
       9              : 
      10              : namespace Amplitron {
      11              : 
      12              : class Reverb : public Effect {
      13              : public:
      14              :     Reverb();
      15              :     void process(float* buffer, int num_samples) override;
      16              :     void process_stereo(float* left, float* right, int num_samples) override;
      17              :     void set_sample_rate(int sample_rate) override;
      18              :     void reset() override;
      19          320 :     const char* name() const override { return "Reverb"; }
      20            3 :     const char* type_id() const override { return "Reverb"; }
      21          212 :     std::vector<EffectParam>& params() override { return params_; }
      22              : 
      23              : private:
      24              :     std::vector<EffectParam> params_;
      25              : 
      26              :     // Schroeder reverb: 4 comb filters + 2 allpass filters
      27              :     static constexpr int NUM_COMBS = 4;
      28              :     static constexpr int NUM_ALLPASS = 2;
      29              : 
      30          392 :     struct CombFilter {
      31              :         std::vector<float> buffer;
      32          392 :         int write_pos = 0;
      33          392 :         float feedback = 0.0f;
      34          392 :         float lp_state = 0.0f;
      35          392 :         float damp = 0.5f;
      36              :     };
      37              : 
      38          196 :     struct AllpassFilter {
      39              :         std::vector<float> buffer;
      40          196 :         int write_pos = 0;
      41          196 :         float feedback = 0.5f;
      42              :     };
      43              : 
      44              :     std::array<CombFilter, NUM_COMBS> combs_;
      45              :     std::array<AllpassFilter, NUM_ALLPASS> allpasses_;
      46              :     // Right-channel filter banks — slightly longer delays for decorrelation
      47              :     std::array<CombFilter, NUM_COMBS> combs_r_;
      48              :     std::array<AllpassFilter, NUM_ALLPASS> allpasses_r_;
      49              : 
      50              :     void init_filters();
      51              : };
      52              : 
      53              : } // namespace Amplitron