a-EQ: Tidy transfer function calculation

diff --git a/libs/plugins/a-eq.lv2/a-eq.c b/libs/plugins/a-eq.lv2/a-eq.c
index dd499092424702652c7ae0758975f96f87efe1b2..fb799d8d8eacc3e11950a2e0aa7589959f41122b 100644 (file)
--- a/libs/plugins/a-eq.lv2/a-eq.c
+++ b/libs/plugins/a-eq.lv2/a-eq.c
@@ -130,7 +130,7 @@ instantiate(const LV2_Descriptor* descriptor,
 {
        Aeq* aeq = (Aeq*)calloc(1, sizeof(Aeq));
        aeq->srate = rate;
-       
+
 #ifdef LV2_EXTENDED
        for (int i=0; features[i]; ++i) {
                if (!strcmp(features[i]->URI, LV2_INLINEDISPLAY__queue_draw)) {
@@ -447,93 +447,146 @@ run(LV2_Handle instance, uint32_t n_samples)
 #endif
 }
 
+static double
+calc_peq(Aeq* self, int i, double omega) {
+       double complex H = 0.0;
+       double complex z = cexp(I * omega);
+       double complex zz = cexp(2. * I * omega);
+       double complex zm = z - 1.0;
+       double complex zp = z + 1.0;
+       double complex zzm = zz - 1.0;
 
-#ifdef LV2_EXTENDED
-static float
-eq_curve (Aeq* self, float f) {
-       float SR = self->srate;
-       double complex H = 1.0;
-       double theta = f * 2. * M_PI / SR;
-       double complex z = cexp(I * theta);
-       double complex zz = cexp(2 * I * theta);
+       double A = pow(10.0, self->v_g[i]/40.0);
+       double g = self->v_filter[i].g;
+       double k = self->v_filter[i].k;
+       double m1 = k * (A * A - 1.0) / A;
+
+       H = (g*k*zzm + A*(g*zp*(m1*zm) + (zm*zm + g*g*zp*zp))) / (g*k*zzm + A*(zm*zm + g*g*zp*zp));
+       return cabs(H);
+}
+
+static double
+calc_lowpass(Aeq* self, double omega) {
+       double complex H = 0.0;
+       double complex z = cexp(I * omega);
+       double complex zz = cexp(2. * I * omega);
        double complex zm = z - 1.0;
        double complex zp = z + 1.0;
        double complex zzm = zz - 1.0;
 
-       double A;
-       double m0, m1, m2, g, k;
+       double g = self->v_filter[5].g;
+       double k = self->v_filter[5].k;
+
+       H = (g*g*zp*zp) / (zm*zm + g*g*zp*zp + g*k*zzm);
+       return cabs(H);
+}
+
+static double
+calc_highpass(Aeq* self, double omega) {
+       double complex H = 0.0;
+       double complex z = cexp(I * omega);
+       double complex zz = cexp(2. * I * omega);
+       double complex zm = z - 1.0;
+       double complex zp = z + 1.0;
+       double complex zzm = zz - 1.0;
+
+       double g = self->v_filter[0].g;
+       double k = self->v_filter[0].k;
+
+       H = zm*zm / (zm*zm + g*g*zp*zp + g*k*zzm);
+       return cabs(H);
+}
+
+static double
+calc_lowshelf(Aeq* self, double omega) {
+       double complex H = 0.0;
+       double complex z = cexp(I * omega);
+       double complex zz = cexp(2. * I * omega);
+       double complex zm = z - 1.0;
+       double complex zp = z + 1.0;
+       double complex zzm = zz - 1.0;
+
+       double A = pow(10.0, self->v_g[0]/40.0);
+       double g = self->v_filter[0].g;
+       double k = self->v_filter[0].k;
+       double m0 = self->v_filter[0].m[0];
+       double m1 = self->v_filter[0].m[1];
+       double m2 = self->v_filter[0].m[2];
+
+       H = (A*m0*zm*zm + g*g*(m0+m2)*zp*zp + sqrt(A)*g*(k*m0+m1) * zzm) / (A*zm*zm + g*g*zp*zp + sqrt(A)*g*k*zzm);
+       return cabs(H);
+}
+
+static double
+calc_highshelf(Aeq* self, double omega) {
+       double complex H = 0.0;
+       double complex z = cexp(I * omega);
+       double complex zz = cexp(2. * I * omega);
+       double complex zm = z - 1.0;
+       double complex zp = z + 1.0;
+       double complex zzm = zz - 1.0;
+
+       double A = pow(10.0, self->v_g[5]/40.0);
+       double g = self->v_filter[5].g;
+       double k = self->v_filter[5].k;
+       double m0 = self->v_filter[5].m[0];
+       double m1 = self->v_filter[5].m[1];
+       double m2 = self->v_filter[5].m[2];
+
+       H = ( sqrt(A) * g * zp * (m1 * zm + sqrt(A)*g*m2*zp) + m0 * ( zm*zm + A*g*g*zp*zp + sqrt(A)*g*k*zzm)) / (zm*zm + A*g*g*zp*zp + sqrt(A)*g*k*zzm);
+       return cabs(H);
+}
+
+#ifdef LV2_EXTENDED
+static float
+eq_curve (Aeq* self, float f) {
+       double complex response = 1.0;
+       double SR = (double)self->srate;
+       double omega = f * 2. * M_PI / SR;
 
        // low
        if (self->v_filtog[0]) {
-               A = pow(10.0, self->v_g[0]/40.0);
-               m0 = self->v_filter[0].m[0];
-               m1 = self->v_filter[0].m[1];
-               m2 = self->v_filter[0].m[2];
-               g = self->v_filter[0].g;
-               k = self->v_filter[0].k;
                if (self->v_shelftogl) {
                        // lowshelf
-                       H *= (A*m0*zm*zm + g*g*(m0+m2)*zp*zp + sqrt(A)*g*(k*m0+m1) * zzm) / (A*zm*zm + g*g*zp*zp + sqrt(A)*g*k*zzm);
+                       response *= calc_lowshelf(self, omega);
                } else {
                        // hp:
-                       H *= zm*zm / (zm*zm + g*g*zp*zp + g*k*zzm);
+                       response *= calc_highpass(self, omega);
                }
        }
 
        // peq1:
        if (self->v_filtog[1]) {
-               A = pow(10.0, self->v_g[1]/40.0);
-               m1 = self->v_filter[1].m[1] / A;
-               g = self->v_filter[1].g;
-               k = self->v_filter[1].k;
-               H *= (g*k*zzm + A*(g*zp*(m1*zm + g*m2*zp) + (zm*zm + g*g*zp*zp))) / (g*k*zzm + A*(zm*zm + g*g*zp*zp));
+               response *= calc_peq(self, 1, omega);
        }
 
        // peq2:
        if (self->v_filtog[2]) {
-               A = pow(10.0, self->v_g[2]/40.0);
-               m1 = self->v_filter[2].m[1] / A;
-               g = self->v_filter[2].g;
-               k = self->v_filter[2].k;
-               H *= (g*k*zzm + A*(g*zp*(m1*zm + g*m2*zp) + (zm*zm + g*g*zp*zp))) / (g*k*zzm + A*(zm*zm + g*g*zp*zp));
+               response *= calc_peq(self, 2, omega);
        }
 
        // peq3:
        if (self->v_filtog[3]) {
-               A = pow(10.0, self->v_g[3]/40.0);
-               m1 = self->v_filter[3].m[1] / A;
-               g = self->v_filter[3].g;
-               k = self->v_filter[3].k;
-               H *= (g*k*zzm + A*(g*zp*(m1*zm + g*m2*zp) + (zm*zm + g*g*zp*zp))) / (g*k*zzm + A*(zm*zm + g*g*zp*zp));
+               response *= calc_peq(self, 3, omega);
        }
 
        // peq4:
        if (self->v_filtog[4]) {
-               A = pow(10.0, self->v_g[4]/40.0);
-               m1 = self->v_filter[4].m[1] / A;
-               g = self->v_filter[4].g;
-               k = self->v_filter[4].k;
-               H *= (g*k*zzm + A*(g*zp*(m1*zm + g*m2*zp) + (zm*zm + g*g*zp*zp))) / (g*k*zzm + A*(zm*zm + g*g*zp*zp));
+               response *= calc_peq(self, 4, omega);
        }
 
        // high
        if (self->v_filtog[5]) {
-               A = pow(10.0, self->v_g[5]/40.0);
-               m0 = self->v_filter[5].m[0];
-               m1 = self->v_filter[5].m[1];
-               m2 = self->v_filter[5].m[2];
-               g = self->v_filter[5].g;
-               k = self->v_filter[5].k;
                if (self->v_shelftogh) {
                        // highshelf:
-                       H *= ( sqrt(A) * g * zp * (m1 * zm + sqrt(A)*g*m2*zp) + m0 * ( zm*zm + A*g*g*zp*zp + sqrt(A)*g*k*zzm)) / (zm*zm + A*g*g*zp*zp + sqrt(A)*g*k*zzm);
+                       response *= calc_highshelf(self, omega);
                } else {
                        // lp:
-                       H *= (g*g*zp*zp) / (zm*zm + g*g*zp*zp + g*k*zzm);
+                       response *= calc_lowpass(self, omega);
                }
        }
 
-       return cabs(H);
+       return response;
 }
 
 static LV2_Inline_Display_Image_Surface *