rewrite filter calculations using plane conversion
this changes everything
This commit is contained in:
parent
c4cfb2582d
commit
7ee3c8f8bd
107
crap_util.c
107
crap_util.c
|
|
@ -15,100 +15,43 @@ biquad_init(biquad *bq) {
|
|||
}
|
||||
|
||||
biquad_interim
|
||||
peaking(double cw, double Gf, double g) {
|
||||
double GB = sqrt(Gf);
|
||||
design(double cw, double sw,
|
||||
double num0, double num1, double num2,
|
||||
double den0, double den1, double den2) {
|
||||
return (biquad_interim) {
|
||||
.b0 = 1 + g * GB,
|
||||
.b1 = -2 * cw,
|
||||
.b2 = 1 - g * GB,
|
||||
.a0 = 1 + g / GB,
|
||||
.a1 = -2 * cw,
|
||||
.a2 = 1 - g / GB
|
||||
};
|
||||
}
|
||||
|
||||
biquad_interim
|
||||
highpass(double cw, double g) {
|
||||
return (biquad_interim) {
|
||||
.b0 = (1 + cw)*0.5,
|
||||
.b1 = -cw - 1,
|
||||
.b2 = (1 + cw)*0.5,
|
||||
.a0 = 1 + g,
|
||||
.a1 = -2*cw,
|
||||
.a2 = 1 - g
|
||||
};
|
||||
}
|
||||
|
||||
/* TODO: rename */
|
||||
biquad_interim
|
||||
orfanidi(double w0, double Gf, double g) {
|
||||
/* simplified http://ece.rutgers.edu/~orfanidi/intro2sp/mdir/peq.m */
|
||||
double Dw, GfS, F, G00, F00, term1, term2, num, den;
|
||||
double G1S, G1, G01, G11, F01, F11, W2, DO, coeff, C, D, A, B;
|
||||
double v;
|
||||
|
||||
Dw = atan(g)*2;
|
||||
GfS = SQR(Gf);
|
||||
|
||||
v = (Gf > 1) ? 1 : -1;
|
||||
|
||||
F = v*(GfS - Gf);
|
||||
G00 = v*(GfS - 1);
|
||||
F00 = v*(Gf - 1);
|
||||
|
||||
term1 = SQR(SQR(w0) - SQR(M_PI));
|
||||
term2 = F00 * SQR(M_PI) * SQR(Dw) / F;
|
||||
num = term1 + term2 * GfS;
|
||||
den = term1 + term2;
|
||||
|
||||
G1S = num/den;
|
||||
G1 = sqrt(G1S);
|
||||
|
||||
G01 = v*(GfS - G1);
|
||||
G11 = v*(GfS - G1S);
|
||||
F01 = v*(Gf - G1);
|
||||
F11 = fabs(Gf - G1S);
|
||||
|
||||
/* bandwidth compensation goes nuts
|
||||
* skip |= v*(Gf - G1S) < 0; */
|
||||
|
||||
W2 = sqrt(G11 / G00) * SQR(tan(w0/2));
|
||||
DO = (1 + sqrt(F00 / F11) * W2) * g;
|
||||
|
||||
coeff = 2 * W2 / F;
|
||||
C = F11 * SQR(DO) / F - coeff * (F01 - sqrt(F00 * F11));
|
||||
D = coeff * (G01 - sqrt(G00 * G11));
|
||||
|
||||
A = sqrt( C + D);
|
||||
B = sqrt(GfS * C + Gf * D);
|
||||
|
||||
return (biquad_interim) {
|
||||
.b0 = -(G1 + W2 + B),
|
||||
.b1 = 2*(G1 - W2),
|
||||
.b2 = -(G1 - B + W2),
|
||||
.a0 = -(1 + W2 + A),
|
||||
.a1 = 2*(1 - W2),
|
||||
.a2 = -(1 + W2 - A)
|
||||
.b0 = num0* (1 + cw) + num1*sw + num2* (1 - cw),
|
||||
.b1 = num0*-2*(1 + cw) + num2*2*(1 - cw),
|
||||
.b2 = num0* (1 + cw) - num1*sw + num2* (1 - cw),
|
||||
.a0 = den0* (1 + cw) + den1*sw + den2* (1 - cw),
|
||||
.a1 = den0*-2*(1 + cw) + den2*2*(1 - cw),
|
||||
.a2 = den0* (1 + cw) - den1*sw + den2* (1 - cw),
|
||||
};
|
||||
}
|
||||
|
||||
biquad
|
||||
biquad_gen(int type, double fc, double gain, double bw, double fs) {
|
||||
/* TODO: use enum for type instead of just int */
|
||||
double w0, cw, sw, Gf, Q, a_peak, a_pass;
|
||||
double w0, cw, sw, A, As, Q;
|
||||
w0 = ANGULAR_LIM(fc, fs);
|
||||
cw = cos(w0);
|
||||
sw = sin(w0);
|
||||
Gf = DB2LIN(gain);
|
||||
Q = 1/(2 * sinh(LN_2_2 * bw * w0/sw));
|
||||
A = DB2LIN(gain/2);
|
||||
As = sqrt(A);
|
||||
Q = 1/(4 * sinh(LN_2_2 * bw * w0/sw));
|
||||
//Q = bw? - (w0/M_PI)^2;
|
||||
/* skip = (fabs(A - 1) <= TINY); */
|
||||
|
||||
a_peak = sw * (2 / Q);
|
||||
a_pass = sw / (1 * Q);
|
||||
/* skip = (fabs(Gf - 1) <= TINY); */
|
||||
biquad_interim bqi;
|
||||
if (type == 0) bqi = peaking(cw, Gf, a_peak);
|
||||
if (type == 1) bqi = orfanidi(w0, Gf, a_peak);
|
||||
if (type == 2) bqi = highpass(cw, a_pass);
|
||||
if (type == 0) bqi = design(cw,sw, 1, A/Q, 1, 1, 1/A/Q, 1);
|
||||
if (type == 1) bqi = design(cw,sw, 1, As/Q, A, 1, 1/As/Q, 1/A);
|
||||
if (type == 2) bqi = design(cw,sw, A, As/Q, 1, 1/A, 1/As/Q, 1);
|
||||
if (type == 3) bqi = design(cw,sw, 0, 0, 1, 1, 1/Q, 1);
|
||||
if (type == 4) bqi = design(cw,sw, 1, 0, 0, 1, 1/Q, 1);
|
||||
if (type == 5) bqi = design(cw,sw, 1, -1/Q, 1, 1, 1/Q, 1);
|
||||
if (type == 6) bqi = design(cw,sw, 0, 1, 0, 1, 1/Q, 1);
|
||||
if (type == 7) bqi = design(cw,sw, 0, 1/Q, 0, 1, 1/Q, 1);
|
||||
if (type == 8) bqi = design(cw,sw, 1, 0, 1, 1, 1/Q, 1);
|
||||
if (type == 9) bqi = design(cw,sw, A, A, A, 1/A, 1/A, 1/A);
|
||||
|
||||
double a0r = 1/bqi.a0;
|
||||
|
||||
|
|
|
|||
27
crap_util.h
27
crap_util.h
|
|
@ -44,18 +44,27 @@ typedef struct {
|
|||
void
|
||||
biquad_init(biquad *bq);
|
||||
|
||||
biquad_interim
|
||||
peaking(double cw, double Gf, double g);
|
||||
|
||||
biquad_interim
|
||||
highpass(double cw, double g);
|
||||
|
||||
biquad_interim
|
||||
orfanidi(double w0, double Gf, double g);
|
||||
|
||||
/* types: TODO: enum
|
||||
0: peaking
|
||||
1: lowshelf
|
||||
2: highshelf
|
||||
3: lowpass
|
||||
4: highpass
|
||||
5: allpass
|
||||
6: bandpass 1
|
||||
7: bandpass 2
|
||||
8: notch
|
||||
9: gain
|
||||
*/
|
||||
biquad
|
||||
biquad_gen(int type, double fc, double gain, double bw, double fs);
|
||||
|
||||
/* s-plane to z-plane */
|
||||
biquad_interim
|
||||
design(double cw, double sw,
|
||||
double num0, double num1, double num2,
|
||||
double den0, double den1, double den2);
|
||||
|
||||
bq_t
|
||||
biquad_run(biquad *bq, bq_t x);
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue
Block a user