added matlab

2025-08-21 07:27:52 +02:00
parent fd522e1b99
commit 64c6745c76
50 changed files with 2516 additions and 0 deletions
@@ -0,0 +1,116 @@
+function eval_blit()
+Nb = 33;
+Nos = 1000;
+fs = 48000;
+f = 440;
+fcut = 16000;
+P = fs/f
+Pi = floor(P)
+Pf = fix(Nos*(fs/f - Pi))
+
+x = (0:Nb*Nos-1) - (Nb*Nos-1)/2;
+H = sinc(2*fcut/fs.*x/Nos).*Kaiser(Nos*Nb, 8)';
+for ii=0:Nos-1,
+    for jj=0:Nb-1
+        Hs(ii+1,jj+1) = H(Nos-ii+Nos*jj);
+    end
+end;
+
+%Hs = init_steps(Nb, Nos);
+
+k = 1./sum(Hs');
+%k = ones(1, Nb);
+y0 = 0;
+y1 = 0;
+y2 = .5;
+ks = 0.002*f/55
+ii = 0;
+ff = 0;
+nn = 1;
+jj = Nb;
+kk = 1;
+for i = 1:32000,
+    if ii == 0
+        jj = 1;
+        kk = ff + 1;
+        ii = Pi;
+        ff = ff + Pf;
+        if ff > (Nos-1)
+            ff = ff - Nos;
+            ii = ii + 1;
+        end
+    end;
+    ii = ii - 1;
+    if jj <= Nb
+        y0 = y0 + k(kk)*Hs(kk,jj); % - ks*y0;
+        jj = jj + 1;
+    end;
+    y0 = y0 - ks*y0;
+    y1 = 1 - y0;
+    y2 = 0.001*y1 + 0.999*y2;
+    blit(nn) = y1-y2;
+    nn = nn + 1;
+end;
+wavwrite(0.7*blit, fs, 'blit.wav');
+
+for ii = 1:Nos
+    step(ii,:) = k(ii).*filter(Hs(ii,:), 1, [ones(1,Nb)]);
+end
+
+close all
+plot(1:length(blit), blit, '-o'); grid;
+
+figure
+plot(abs(fft(blit))); grid;
+
+figure
+plot(step', '-'); grid;
+
+figure
+plot(Hs(1,:)', '-+'); grid;
+
+function steps = init_steps(step_width, phase_count)
+
+low_pass  = 0.999; % lower values filter more high frequency
+high_pass = 0.990; % lower values filter more low frequency
+
+%phase_count = 32; % number of phase offsets to sample band-limited step at
+%step_width  = 16; % number of samples in each final band-limited step
+
+%steps [phase_count] [step_width]; // would use short for speed in a real program
+
+	% Generate master band-limited step by adding sine components of a square wave
+	master_size = step_width * phase_count;
+	% master [master_size]; // large; might want to malloc() instead
+	for i = 0:master_size-1
+		master(i+1) = 0.5;
+    end;
+    
+    gain = 0.5 / 0.777; % adjust normal square wave's amplitude of ~0.777 to 0.5
+	sine_size = 256 * phase_count + 2;
+	max_harmonic = sine_size / 2 / phase_count;
+	for h = 1:2:max_harmonic
+		amplitude = gain / h;
+		to_angle = 3.14159265358979323846 * 2 / sine_size * h;
+    	for i = 0:master_size-1
+			master(i+1) = master(i+1) + sin( (i - master_size / 2) * to_angle ) * amplitude;
+        end
+		gain = gain * low_pass;
+    end
+	
+	% Sample master step at several phases
+	for phase = 0:phase_count-1
+		error = 1.0;
+		prev = 0.0;
+    	for i = 0:step_width-1
+			cur = master (i * phase_count + (phase_count - 1 - phase)+1);
+			delta = cur - prev;
+			error = error - delta;
+			prev = cur;
+			steps (phase+1, i+1) = delta;
+        end
+		
+		% each delta should total 1.0
+		steps (phase+1, step_width / 2) = steps (phase+1, step_width / 2) + error * 0.5;
+		steps (phase+1, step_width / 2 + 1) = steps (phase+1, step_width / 2 + 1) + error * 0.5;
+    end