Line data    Source code

       1              : #pragma once
       2              : 
       3              : // Cascaded all-pass phaser with LFO modulation.
       4              : // Each all-pass stage has near-unity magnitude and phase shift A(z); mixing
       5              : // dry + wet creates notches where phase cancellation occurs. The LFO modulates
       6              : // the all-pass coefficient so notch frequencies sweep over time.
       7              : 
       8              : #include <array>
       9              : 
      10              : #include "audio/effects/core/effect.h"
      11              : 
      12              : namespace Amplitron {
      13              : 
      14              : /**
      15              :  * Phaser effect — cascaded 1st-order all-pass filters with LFO modulation.
      16              :  * Supports 4, 6, 8, or 12 stages (classic MXR Phase 90 to studio phasers).
      17              :  */
      18            6 : class Phaser : public Effect {
      19              :    public:
      20              :     Phaser();
      21              :     void process(float* buffer, int num_samples) override;
      22              :     void process_stereo(float* left, float* right, int num_samples) override;
      23              :     void set_sample_rate(int sample_rate) override;
      24              :     void reset() override;
      25           65 :     const char* name() const override { return "Phaser"; }
      26            3 :     const char* type_id() const override { return "Phaser"; }
      27           97 :     std::vector<EffectParam>& params() override { return params_; }
      28            0 :     const std::vector<EffectParam>& params() const override { return params_; }
      29              : 
      30              :    private:
      31              :     std::vector<EffectParam> params_;
      32              : 
      33              :     float lfo_phase_ = 0.0f;
      34              :     float feedback_state_ = 0.0f;
      35              :     float feedback_state_r_ = 0.0f;  // right-channel APF feedback
      36              : 
      37              :     static constexpr int MAX_STAGES = 12;
      38              :     std::array<float, MAX_STAGES> apf_xprev_{};
      39              :     std::array<float, MAX_STAGES> apf_yprev_{};
      40              :     // Right-channel APF state — LFO is 180° out of phase for stereo sweep
      41              :     std::array<float, MAX_STAGES> apf_xprev_r_{};
      42              :     std::array<float, MAX_STAGES> apf_yprev_r_{};
      43              : };
      44              : 
      45              : }  // namespace Amplitron