percussion_detector.h

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#pragma once
 
#include "fl/stl/function.h"
#include "fl/stl/noexcept.h"
 
namespace fl {
namespace audio {
namespace detector {
 
class Percussion {
public:
    Percussion() FL_NOEXCEPT;
    ~Percussion() FL_NOEXCEPT;
 
    void update(shared_ptr<Context> context);
    void reset();
 
    // Cooldown periods to prevent double-triggering (in milliseconds)
    static constexpr u32 KICK_COOLDOWN_MS = 50;
    static constexpr u32 SNARE_COOLDOWN_MS = 50;
    static constexpr u32 HIHAT_COOLDOWN_MS = 30;
 
    // Percussion detection callbacks (multiple listeners supported)
    function_list<void()> onKick;
    function_list<void()> onSnare;
    function_list<void()> onHiHat;
    function_list<void()> onTom;
    function_list<void(const char* type)> onPercussionHit;
 
    // Configuration methods
    void setKickThreshold(float threshold) { mKickThreshold = threshold; }
    void setSnareThreshold(float threshold) { mSnareThreshold = threshold; }
    void setHiHatThreshold(float threshold) { mHiHatThreshold = threshold; }
 
private:
    // Detection thresholds
    float mKickThreshold;
    float mSnareThreshold;
    float mHiHatThreshold;
 
    // Previous energy tracking
    float mPrevBassEnergy;
    float mPrevMidEnergy;
    float mPrevTrebleEnergy;
 
    // Timestamp tracking to prevent double-triggering
    u32 mLastKickTime;
    u32 mLastSnareTime;
    u32 mLastHiHatTime;
 
    // Energy band calculations
    float getBassEnergy(const fft::Bins& fft);
    float getMidEnergy(const fft::Bins& fft);
    float getTrebleEnergy(const fft::Bins& fft);
 
    // Percussion type detection
    bool detectKick(float bassEnergy, float bassFlux, u32 timestamp);
    bool detectSnare(float midEnergy, float midFlux, u32 timestamp);
    bool detectHiHat(float trebleEnergy, float trebleFlux, u32 timestamp);
};
 
} // namespace detector
} // namespace audio
} // namespace fl