adsr_gen.m

function a = adsr_gen(target, gain, duration)
% Input %   target - vector of attack, sustain, release target values
%   gain - vector of attack, sustain, release gain values
%   duration - vector of attack, sustain, release durations in ms
% Output
%   a - vector of adsr envelope values
%fs =16000;
%a = zeros(duration(1)+duration(2)+duration(3)+1);  % assume 1 second duration ADSR envelope
%duration = round(duration.*fs); % envelope duration in samp
% Attack phase
start = 2;
stop = duration(1);
a(1)=0;
for n = start:stop
    a(n) = target(1)*gain(1) + (1.0 - gain(1))*a(n - 1);
end
% Sustain phase
start = stop + 1;
stop = start -1 + duration(2);
for n = start:stop
    a(n) = target(2)*gain(2) + (1.0 - gain(2))*a(n - 1);
end
% Release phase
start = stop + 1;
stop =start -1 + duration(3);
for n = start:stop
    a(n) = target(3)*gain(3) + (1.0 - gain(3))*a(n - 1);
end;