EnvelopeDetector.h

/*
==============================================================================

EnvelopeDetector.h
Created: 16 Dec 2017 9:49:56pm
Author:  Toby

==============================================================================
*/
#pragma once
// turn off non-critical warnings
#pragma warning(disable : 4244)//double to float
#pragma warning(disable : 4996)//strncpy
#pragma warning(disable : 4305)//double float truncation

#include <stdio.h>
#include <stdlib.h>
#include <string.h>


// For WIN vs MacOS
// XCode requires these be defined for compatibility
#if defined _WINDOWS || defined _WINDLL
#include <windows.h>
#else // MacOS
typedef unsigned int        UINT;
typedef unsigned long       DWORD;
typedef unsigned char		UCHAR;
typedef unsigned char       BYTE;
#endif

#include <math.h>



// constants for dealing with overflow or underflow
#define FLT_EPSILON_PLUS      1.192092896e-07         /* smallest such that 1.0+FLT_EPSILON != 1.0 */
#define FLT_EPSILON_MINUS    -1.192092896e-07         /* smallest such that 1.0-FLT_EPSILON != 1.0 */
#define FLT_MIN_PLUS          1.175494351e-38         /* min positive value */
#define FLT_MIN_MINUS        -1.175494351e-38         /* min negative value */

const float DIGITAL_TC = -2.0; // log(1%)
const float ANALOG_TC = -0.43533393574791066201247090699309; // (log(36.7%)
const float METER_UPDATE_INTERVAL_MSEC = 15.0;
const float METER_MIN_DB = -60.0;

class CEnvelopeDetector
{
public:
	CEnvelopeDetector(void);
	~CEnvelopeDetector(void);

public:

	// Call the Init Function to initialize and setup all at once; this can be called as many times
	// as you want
	void init(float samplerate, float attack_in_ms, float release_in_ms, bool bAnalogTC, UINT uDetect, bool bLogDetector);

	// these functions allow you to change modes and attack/release one at a time during
	// realtime operation
	void setTCModeAnalog(bool bAnalogTC); // {m_bAnalogTC = bAnalogTC;}

										  // THEN do these after init
	void setAttackTime(float attack_in_ms);
	void setReleaseTime(float release_in_ms);

	// Use these "codes"
	// DETECT PEAK   = 0
	// DETECT MS	 = 1
	// DETECT RMS	 = 2
	//
	void setDetectMode(UINT uDetect) { m_uDetectMode = uDetect; }

	void setSampleRate(float f) { m_fSampleRate = f; }

	void setLogDetect(bool b) { m_bLogDetector = b; }

	// call this to detect; it returns the peak ms or rms value at that instant
	float detect(float fInput);

	// call this from your prepareForPlay() function each time to reset the detector
	void prepareForPlay();

protected:
	int  m_nSample;
	float m_fAttackTime;
	float m_fReleaseTime;
	float m_fAttackTime_mSec;
	float m_fReleaseTime_mSec;
	float m_fSampleRate;
	float m_fEnvelope;
	UINT  m_uDetectMode;
	bool  m_bAnalogTC;
	bool  m_bLogDetector;
};

inline double lagrpol(double* x, double* y, int n, double xbar)
{
	int i, j;
	double fx = 0.0;
	double l = 1.0;
	for (i = 0; i<n; i++)
	{
		l = 1.0;
		for (j = 0; j<n; j++)
		{
			if (j != i)
				l *= (xbar - x[j]) / (x[i] - x[j]);
		}
		fx += l * y[i];
	}
	return (fx);
}