From 7ee3c8f8bde4f9a9b2a0c6ebab1bd640cacaf9b5 Mon Sep 17 00:00:00 2001 From: Connor Olding Date: Tue, 10 Sep 2013 02:54:14 -0700 Subject: [PATCH] rewrite filter calculations using plane conversion this changes everything --- crap_util.c | 107 ++++++++++++---------------------------------------- crap_util.h | 27 ++++++++----- 2 files changed, 43 insertions(+), 91 deletions(-) diff --git a/crap_util.c b/crap_util.c index 287e039..2c2fd6a 100644 --- a/crap_util.c +++ b/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; diff --git a/crap_util.h b/crap_util.h index fe13c2c..9996589 100644 --- a/crap_util.h +++ b/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);