seance2

q1 3.m

+t = 0:0.01:3;
+amplitudes = 10.^([77.25 75.91 60.74 63.01 59.83 56.54 55.12 41.16]/20);
+frequences = [220.46 442.12 663.62 885.62 1108.42 1331.54 1556.29 1782.8];
+
+y = zeros(size(t));  % initialiser le signal
+
+for k = 1:length(amplitudes)
+    y = y + amplitudes(k) * sin(2*pi*frequences(k)*t);
+end
+
+figure(1);
+plot(t, y);
+
+xlabel('temps (s)');
+ylabel('Amplitude');
+title('Piano1/superposition');
+grid;

q1 4.m

+fs = 44100;        % frquence d'chantillonnage
+dur = 2;           % dure du signal (en secondes)
+t = 0:(1/fs):dur;  % axe temporel
+
+% Amplitudes et frquences
+amplitudes = 10.^([77.25 75.91 60.74 63.01 59.83 56.54 55.12 41.16]/20);
+frequences = [220.46 442.12 663.62 885.62 1108.42 1331.54 1556.29 1782.8];
+
+% Gnration du signal
+y = zeros(size(t));
+for k = 1:length(amplitudes)
+    y = y + amplitudes(k) * sin(2*pi*frequences(k)*t);
+end
+
+% -- (Optionnel) enveloppe ADSR --
+% Paramtres ADSR
+attack = 0.1; decay = 0.05; sustain = 0.7; sustainTime = 1.4; release = 0.4;
+attackS = round(attack*fs);
+decayS = round(decay*fs);
+sustainS = round(sustainTime*fs);
+releaseS = round(release*fs);
+
+% Cration de l'enveloppe
+env = [linspace(0, 1, attackS), ...
+       linspace(1, sustain, decayS), ...
+       sustain*ones(1, sustainS), ...
+       linspace(sustain, 0, releaseS)];
+env = [env, zeros(1, length(t) - length(env))];  % complter si besoin
+
+% Appliquer l'enveloppe
+yenv = y .* env;
+
+plot(t,y,'b');
+hold on
+plot(t,yenv,'r');
+
+% Lecture ou sauvegarde
+% audiowrite('piano_synthetise.wav', y, fs);  % pour sauvegarder
+

q2 1.m

+Fe = 44100
+T = 1/440;
+t = 0:1/Fe:1;
+x_square = square(2*pi*t/T);
+x_saw = sawtooth(2*pi*t/T);
+disp(x_square)
+plot(t, x_square);
+plot(t, x_saw);
+
+
+X_sq = fftshift(fft(x_square));
+X_sw = fftshift(fft(x_saw));
+
+% Filtrage passe-bas d'ordre 1
+y_lp = filter([0.5, 0.5], 1, x_saw);
+