Attack Decay Sustain Release

Envelope of sound

You're already there? Holly molly you were fast! We're still ironing out the part of this workshop (read: it was too sunny outside to stay inside...). Some code will come up soon, and explanations will shortly follow.

struct note {

    enum { ATTACK, DECAY, SUSTAIN, RELEASE, SLEEP} state = ATTACK; 
    float freq;
    int i_start;
    // Attack Decay Sustain Release
    float t_a = 1.2;
    float t_d = 0.3;
    float a_s = 0.7;
    float t_r = 0.1;

    note(float _freq, int _i) { freq = _freq; i_start =_i; }

    //Attack Decay Sustain Release
    float ADSR( int _i) {

        float tps = 1.0/4410;
        switch(state) {
        case ATTACK:
//          std::cout << "A " << (_i - i_start)*tps << " " << (_i - i_start)*tps/t_a<< std::endl;
            if( (_i - i_start)*tps > t_a) {
            i_start = _i;
            state=DECAY;
            }
            return (_i - i_start)*tps/t_a;
            break;

        case DECAY:
//          std::cout << "D " << (_i - i_start)*tps << std::endl;
            if( (_i - i_start)*tps > t_d) {
            i_start = _i;
            state=SUSTAIN;
            }
            return 1-(1-a_s)*(_i - i_start)*tps/t_d;
            break;

        case SUSTAIN:
//          std::cout << "S " << std::endl;
            return a_s;
            break;

        case RELEASE:
//          std::cout << "R " << (_i - i_start)*tps << std::endl;
            if( (_i - i_start)*tps > t_r)
            state=SLEEP;
            return a_s*(1-(_i - i_start)*tps/t_r);
            break;

        }

        return 1;
    }

};

And add in the callback: