SimpleEnvelope.h

/*
 *  Simple Envelope Detectors (header)
 *
 *  File        : SimpleEnvelope.h
 *  Library     : SimpleSource
 *  Version     : 1.12
 *  Class       : EnvelopeDetector, AttRelEnvelope
 *
 *  2006, ChunkWare Music Software, OPEN-SOURCE
 *
 *  Permission is hereby granted, free of charge, to any person obtaining a
 *  copy of this software and associated documentation files (the "Software"),
 *  to deal in the Software without restriction, including without limitation
 *  the rights to use, copy, modify, merge, publish, distribute, sublicense,
 *  and/or sell copies of the Software, and to permit persons to whom the
 *  Software is furnished to do so, subject to the following conditions:
 *
 *  The above copyright notice and this permission notice shall be included in
 *  all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 *  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 *  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 *  THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 *  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 *  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 *  DEALINGS IN THE SOFTWARE.
 */
 
 
#ifndef __SIMPLE_ENVELOPE_H__
#define __SIMPLE_ENVELOPE_H__
 
#include "SimpleHeader.h"   // common header
 
namespace chunkware_simple
{
    //-------------------------------------------------------------
    // DC offset (to prevent denormal)
    //-------------------------------------------------------------
 
    // USE:
    // 1. init envelope state to DC_OFFSET before processing
    // 2. add to input before envelope runtime function
    static constexpr double DC_OFFSET = 1.0E-25;
 
    class EnvelopeDetector
    {
    public:
        EnvelopeDetector(double ms = 1.0, double sampleRate = 44100.0);
 
        virtual ~EnvelopeDetector() {}
 
        virtual void   setTc(double ms);
 
        virtual double getTc(void) const { return ms_; }
 
        virtual void   setSampleRate(double sampleRate);
 
        virtual double getSampleRate(void) const { return sampleRate_; }
 
        INLINE void run(double in, double &state)
        {
            state = in + coef_ * (state - in);
        }
 
    protected:
        virtual void setCoef(void); 
 
        double sampleRate_;         
        double ms_;                 
        double coef_;               
    };  // end SimpleComp class
 
    class AttRelEnvelope
    {
    public:
        AttRelEnvelope(double att_ms = 10.0, double rel_ms = 100.0, double sampleRate = 44100.0);
 
        virtual ~AttRelEnvelope() {}
 
        virtual void   setAttack(double ms);
        virtual double getAttack(void) const { return att_.getTc(); }
 
        virtual void   setRelease(double ms);
        virtual double getRelease(void) const { return rel_.getTc(); }
 
        virtual void   setSampleRate(double sampleRate);
        virtual double getSampleRate(void) const { return att_.getSampleRate(); }
 
        INLINE void run(double in, double &state)
        {
 
            /* assumes that:
            * positive delta = attack
            * negative delta = release
            * good for linear & log values
            */
 
            if (in > state)
                att_.run(in, state);     // attack
            else
                rel_.run(in, state);     // release
        }
 
    private:
        EnvelopeDetector att_;
        EnvelopeDetector rel_;
 
    };  // end AttRelEnvelope class
 
}   // end namespace chunkware_simple
 
#endif  // end __SIMPLE_ENVELOPE_H__