envelope_detector.h

/*
 * EasyListener for Teensy Audio Library
 * 
 * (c) 2020 Clemens Wegener 
 * Bauhaus-Universität Weimar
 * Department Interface Design
 *
 * This library uses machine learning to detect previously 
 * presented audio signals on the Teensy board. 
 *
 * BSD license
 */
#ifndef envelope_detector_h_
#define envelope_detector_h_

#include "core_pins.h"
#include "AudioStream.h"
#include "event_detector.h"
#include "Arduino.h"


class EnvelopeDetector : public EventDetector 
{
  public:
    EnvelopeDetector(float threshold_db, float decay, int16_t min_number_of_blocks):
    _envelope(0),
    _peak(0),
    _new_env_available(false),
    _decay(decay),
    _threshold(dbToa(threshold_db)*(float)32767.0), // convert from db to 16bit fixed point amplitude
    _threshold_crossed(false),
    _new_threshold_crossed_available(false),
    _sound_is_long_enough(false),
    _new_sound_detected(false),
    _block_count(0),
    _min_number_of_blocks(min_number_of_blocks),
    _frame_num(0)
    { };
      
    void process(const int16_t *data, uint16_t frame_num);
    void setDecayRate(float decay);
    void setThreshold(float threshold);
    
    // don't call this function internally
    // it is meant to be used to limit data 
    // when streaming to serial port
    bool eventOngoingAvailable() {
        bool flag = _new_threshold_crossed_available;
        _new_threshold_crossed_available = false;
        return flag;
    }
    
    bool eventOngoing() {
        return _threshold_crossed;
    }
    
    bool envelopeAvailable() {
        bool flag = _new_env_available;
        _new_env_available = false;
        return flag;
    }

    int16_t getEnvelope() {
        return _peak;
    }
    
    float getEnvelopeDB() {
        return aTodb((float)_peak/(float)32767.0);
    }

    bool eventValid() {
        bool flag = _new_sound_detected;
        _new_sound_detected = false;
        return flag;
    }

    uint16_t getFrameNum() {return _frame_num;}
    
    static float aTodb(const float a) {
        return 20.0*log10f(a);
    }

    static float dbToa(const float db) {
        return powf(10,(db/20.0));
    }
    

    ~EnvelopeDetector(){}
          
  private:
    int16_t *data;
    int _envelope;
    int _peak;
    bool _new_env_available;
    float _decay;
    float _threshold;
    bool _threshold_crossed;
    bool _new_threshold_crossed_available;
    bool _sound_is_long_enough;
    bool _new_sound_detected;
    int16_t _block_count;
    int16_t _min_number_of_blocks;
    uint16_t _frame_num;
};

#endif