pitch.h

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#pragma once
 
#include "fl/audio/audio_detector.h"
#include "fl/math/filter/filter.h"
#include "fl/stl/function.h"
#include "fl/stl/vector.h"
#include "fl/stl/noexcept.h"
 
namespace fl {
namespace audio {
namespace detector {

class Pitch : public Detector {
public:
    Pitch() FL_NOEXCEPT;
    ~Pitch() FL_NOEXCEPT override;
 
    void update(shared_ptr<Context> context) override;
    void fireCallbacks() override;
    bool needsFFT() const override { return false; }  // Uses PCM data directly
    const char* getName() const override { return "Pitch"; }
    void reset() override;
 
    // Callbacks (multiple listeners supported)
    function_list<void(float hz)> onPitch;  // Continuous pitch updates
    function_list<void(float hz, float confidence)> onPitchWithConfidence;
    function_list<void(float hz)> onPitchChange;  // Fires when pitch changes significantly
    function_list<void(u8 voiced)> onVoiced;  // Fires when voiced/unvoiced state changes
 
    // State access
    float getPitch() const { return mCurrentPitch; }
    float getConfidence() const { return mConfidence; }
    bool isVoiced() const { return mIsVoiced; }  // True if pitched sound detected
    float getSmoothedPitch() const { return mSmoothedPitch; }
 
    // Configuration
    void setMinFrequency(float hz) { mMinFrequency = hz; updatePeriodRange(); }
    void setMaxFrequency(float hz) { mMaxFrequency = hz; updatePeriodRange(); }
    void setConfidenceThreshold(float threshold) { mConfidenceThreshold = threshold; }
    void setSmoothingFactor(float) { /* OneEuroFilter adapts automatically */ }
    void setPitchChangeSensitivity(float sensitivity) { mPitchChangeSensitivity = sensitivity; }
 
private:
    // Current state
    float mCurrentPitch;      // Current detected pitch in Hz
    float mSmoothedPitch;     // Exponentially smoothed pitch
    float mConfidence;        // Detection confidence (0-1)
    bool mIsVoiced;           // True if currently detecting pitched sound
    bool mPreviousVoiced;     // Previous voiced state for change detection
    float mPreviousPitch;     // Previous pitch for change detection
    bool mFirePitch = false;
    bool mFirePitchChange = false;
    bool mVoicedStateChanged = false;
 
    // Configuration
    float mMinFrequency;      // Minimum detectable frequency (Hz)
    float mMaxFrequency;      // Maximum detectable frequency (Hz)
    float mConfidenceThreshold;  // Minimum confidence to report pitch
    float mPitchChangeSensitivity;  // Sensitivity for pitch change detection (Hz)
 
    // Adaptive pitch smoothing: low jitter when stable, low lag on changes
    OneEuroFilter<float> mPitchSmoother{1.0f, 0.5f};
    float mLastDt = 0.023f; // Computed from pcmSize / sampleRate each frame
 
    // Autocorrelation parameters
    int mMinPeriod;           // Minimum period in samples
    int mMaxPeriod;           // Maximum period in samples
    float mSampleRate;        // Audio sample rate (Hz)
 
    // Autocorrelation buffer
    vector<float> mAutocorrelation;
 
    // Helper methods
    void updatePeriodRange();
    float calculateAutocorrelation(const i16* pcm, size numSamples);
    float periodToFrequency(int period) const;
    int frequencyToPeriod(float frequency) const;
    float calculateConfidence(const vector<float>& autocorr, int peakLag) const;
    int findBestPeakLag(const vector<float>& autocorr) const;
    void updatePitchSmoothing(float newPitch);
    bool shouldReportPitchChange(float newPitch) const;
};
 
} // namespace detector
} // namespace audio
} // namespace fl