noise_floor_tracker.h

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#pragma once
 
#include "fl/stl/int.h"
#include "fl/stl/noexcept.h"
 
namespace fl {
namespace audio {

struct NoiseFloorTrackerConfig {
    bool enabled = true;

    float decayRate = 0.99f;

    float attackRate = 0.001f;

    float hysteresisMargin = 100.0f;

    float minFloor = 10.0f;

    float maxFloor = 5000.0f;

    float crossDomainWeight = 0.3f;
};

class NoiseFloorTracker {
public:
    NoiseFloorTracker() FL_NO_EXCEPT;
    explicit NoiseFloorTracker(const NoiseFloorTrackerConfig& config) FL_NO_EXCEPT;
    ~NoiseFloorTracker() FL_NO_EXCEPT;

    void configure(const NoiseFloorTrackerConfig& config) FL_NO_EXCEPT;

    void update(float timedomainLevel, float frequencydomainLevel = -1.0f) FL_NO_EXCEPT;

    float getFloor() const FL_NO_EXCEPT { return mCurrentFloor; }

    float normalize(float level) const FL_NO_EXCEPT;

    bool isAboveFloor(float level) const FL_NO_EXCEPT;

    void reset() FL_NO_EXCEPT;

    struct Stats {
        float currentFloor = 0.0f;        // Current noise floor estimate
        float minObserved = 0.0f;         // Minimum level observed (lifetime)
        float maxObserved = 0.0f;         // Maximum level observed (lifetime)
        u32 samplesProcessed = 0;         // Total samples processed
        bool inHysteresis = false;        // Whether hysteresis is active
    };
 
    const Stats& getStats() const FL_NO_EXCEPT { return mStats; }
 
private:
    void updateFloor(float level) FL_NO_EXCEPT;

    float combineDomains(float timeLevel, float freqLevel) const FL_NO_EXCEPT;
 
    NoiseFloorTrackerConfig mConfig;
    Stats mStats;

    float mCurrentFloor = 100.0f;

    float mLastHysteresisFloor = 0.0f;

    u32 mBelowFloorCount = 0;

    static constexpr u32 BELOW_FLOOR_THRESHOLD = 10;
};
 
} // namespace audio
} // namespace fl