% Linear/Exponentiel Envelope Test
%
% 2025-07-17 mchris
%
% Sampling parameters
Fs = 44100;
T = 2;
t = linspace(0, T, Fs*T);

% Envelope parameters
tau = 0.5;
delay = 0.5;
delaySamples = round(delay * Fs);

% Exponential decay envelope (already implemented)
envelope_exp = zeros(size(t));
envelope_exp(delaySamples+1:end) = exp(-(t(1:end - delaySamples))/tau);

% Linear decay envelope
envelope_lin = zeros(size(t));
decay_length = length(t) - delaySamples; % length after delay
envelope_lin(delaySamples+1:end) = linspace(1,0,decay_length);

% Sine wave
f = 440;
signal = sin(2 * pi * f * t);

% Modulated signals
modulated_signal_exp = signal .* envelope_exp;
modulated_signal_lin = signal .* envelope_lin;

% Normalize for audio
modulated_signal_exp = modulated_signal_exp / max(abs(modulated_signal_exp));
modulated_signal_lin = modulated_signal_lin / max(abs(modulated_signal_lin));

% Play linear decay version
printf("play linear");
sound(modulated_signal_lin, Fs);

printf("play exponentiel");
% Play exponential version
sound(modulated_signal_exp, Fs);

% (Optional) Plot both envelopes
figure;
plot(t, envelope_exp, 'r', t, envelope_lin, 'b--');
legend('Exponential envelope','Linear envelope');
xlabel('Time (s)'); ylabel('Amplitude');
title('Envelope Comparison');