moog filter
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2
Makefile
2
Makefile
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@ -5,7 +5,7 @@ FULLNAME = $(DISTNAME)-$(VERSION)
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BIN ?= ./bin
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VST_SDK_DIR ?= .
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BOTH = eq eq_const eq_const_T420 eq_const_T420_svf noise tube
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BOTH = eq eq_const eq_const_T420 eq_const_T420_svf mugi4 noise tube
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LADSPA = $(BOTH)
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VST = $(BOTH) delay_test
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208
crap/mugi4.h
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208
crap/mugi4.h
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@ -0,0 +1,208 @@
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#define ID (0xD8D0D8D0)
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#define LABEL "crap_mugi4"
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#define NAME "crap mugi4 (moog-like)"
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#define AUTHOR "Connor Olding"
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#define COPYRIGHT "MIT"
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#define PARAMETERS 3
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/*
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an implementation of:
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S. D Angelo and V. Välimäki. Generalized Moog Ladder Filter: Part II
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Explicit Nonlinear Model through a Novel Delay-Free Loop Implementation Method.
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IEEE Trans. Audio, Speech, and Lang. Process.,
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vol. 22, no. 12, pp. 1873 1883, December 2014.
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https://aaltodoc.aalto.fi/bitstream/handle/123456789/14420/article6.pdf
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*/
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#define OVERSAMPLING 2
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#define BLOCK_SIZE 256
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#define FULL_SIZE (BLOCK_SIZE*OVERSAMPLING)
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#include <stdio.h>
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#include <string.h>
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#include "util.h"
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#include "param.h"
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#include "os2piir_stereo.h"
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#define VT 0.026
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#define N 4
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#define VT2 V(2.*VT)
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typedef struct {
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v2df sum, sumback, dout;
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} stage;
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typedef struct {
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v2df g;
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v2df p0;
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v2df q0, q1, q2, q3;
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v2df r1, r2, r3, r4;
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v2df L_p0;
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v2df L_q0;
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v2df L_r1;
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} freqdata;
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typedef struct {
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ulong fs;
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halfband_t hb_up, hb_down;
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freqdata fd;
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stage s1, s2, s3, s4;
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v2df sumback1, sumback2, sumback3, sumback4;
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v2df drive, feedback;
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} personal;
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INNER PURE v2df
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tanh2(v2df x)
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{
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//return (v2df){tanh(x[0]), tanh(x[1])};
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v2df xx = x*x;
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v2df a = ((xx + V(378.))*xx + V(17325.))*xx + V(135135.);
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v2df b = ((V(28.)*xx + V(3150.))*xx + V(62370.))*xx + V(135135.);
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return x*a/b;
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}
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INNER v2df
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process_stage(stage *s, freqdata fd, v2df in)
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{
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v2df temp = (in + s->sumback)*VT2*fd.L_p0*fd.g;
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v2df out = temp + s->sum;
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s->sum += V(2.)*temp;
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s->dout = tanh2(out/VT2);
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s->sumback = in*fd.L_r1 - s->dout*fd.L_q0;
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return out;
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}
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INNER v2df
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process_one(v2df in, personal *data)
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{
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const freqdata fd = data->fd;
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in *= data->drive;
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v2df sum = in + data->sumback1;
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v2df pre = -fd.p0*sum;
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process_stage(&data->s1, fd, tanh2(pre/VT2));
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process_stage(&data->s2, fd, data->s1.dout);
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process_stage(&data->s3, fd, data->s2.dout);
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v2df out = process_stage(&data->s4, fd, data->s3.dout);
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v2df back = data->feedback*out;
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data->sumback1 = fd.r1*in + fd.q0*back + data->sumback2;
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data->sumback2 = fd.r2*in + fd.q1*back + data->sumback3;
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data->sumback3 = fd.r3*in + fd.q2*back + data->sumback4;
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data->sumback4 = fd.r4*in + fd.q3*back;
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v2df compensate = -(data->feedback + V(1.));
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return out/data->drive*compensate;
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}
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static void
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process_double(personal *data,
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double *in_L, double *in_R,
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double *out_L, double *out_R,
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unsigned long count)
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#include "process_mugi4.h"
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static void
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process(personal *data,
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float *in_L, float *in_R,
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float *out_L, float *out_R,
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ulong count)
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#include "process_mugi4.h"
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INNER void
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construct(personal *data)
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{
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memset(data, 0, sizeof(personal));
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}
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INNER void
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construct_params(param *params)
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{
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sprintf(params[0].name, "Frequency");
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params[0].min = 20;
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params[0].max = 20000;
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params[0].scale = SCALE_HZ;
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params[0].def = DEFAULT_MAX;
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sprintf(params[1].name, "Drive");
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params[1].min = -40;
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params[1].max = 0;
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params[1].scale = SCALE_DB;
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params[1].def = DEFAULT_MIN;
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sprintf(params[2].name, "Feedback");
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params[2].min = 0;
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params[2].max = 1;
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params[2].scale = SCALE_FLOAT;
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params[2].def = DEFAULT_MIN;
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param_reset(¶ms[0]);
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param_reset(¶ms[1]);
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param_reset(¶ms[2]);
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}
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INNER void
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destruct(personal *data)
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{}
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INNER void
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resume(personal *data)
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{
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memset(&data->hb_up, 0, sizeof(halfband_t));
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memset(&data->hb_down, 0, sizeof(halfband_t));
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}
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INNER void
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pause(personal *data)
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{}
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INNER void
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adjust(personal *data, param *params, ulong fs_long)
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{
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double fs = fs_long;
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data->fs = fs_long;
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double f = params[0].value;
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if (f < 20) f = 20;
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if (f > fs/6*OVERSAMPLING) f = fs/6*OVERSAMPLING;
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double drive = DB2LIN(params[1].value);
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double k = params[2].value*N;
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data->drive = (v2df){drive, drive};
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data->feedback = (v2df){k, k};
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double bc1 = -4; //-binomial(N, 1);
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double bc2 = -6; //-binomial(N, 2);
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double bc3 = -4; //-binomial(N, 3);
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double bc4 = -1; //-binomial(N, 4);
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freqdata fd;
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#define fd_set(L, R) double L = R; fd.L = (v2df){L, L}
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fd_set(g, tan(M_PI*f/fs/OVERSAMPLING));
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double gg1 = g/(g + 1);
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double gg1Nk = k*gg1*gg1*gg1*gg1;
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double g1g1 = (g - 1)/(g + 1);
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fd_set(p0, 1/(1 + gg1Nk));
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fd_set(r1, bc1*gg1Nk);
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fd_set(r2, bc2*gg1Nk);
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fd_set(r3, bc3*gg1Nk);
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fd_set(r4, bc4*gg1Nk);
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fd_set(q0, r1 + bc1*g1g1);
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fd_set(q1, r2 + bc2*g1g1*g1g1);
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fd_set(q2, r3 + bc3*g1g1*g1g1*g1g1);
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fd_set(q3, r4 + bc4*g1g1*g1g1*g1g1*g1g1);
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fd_set(L_p0, 1/(1 + g));
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fd_set(L_q0, 1 - g);
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fd_set(L_r1, -g);
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#undef fd_set
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data->fd = fd;
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}
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INNER void
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adjust_one(personal *data, param *params, unsigned int index)
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{
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adjust(data, params, data->fs);
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}
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45
include/process_mugi4.h
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45
include/process_mugi4.h
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@ -0,0 +1,45 @@
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{
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disable_denormals();
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v2df buf[BLOCK_SIZE];
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v2df over[FULL_SIZE];
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halfband_t *hb_up = &data->hb_up;
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halfband_t *hb_down = &data->hb_down;
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for (ulong pos = 0; pos < count; pos += BLOCK_SIZE) {
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ulong rem = BLOCK_SIZE;
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if (pos + BLOCK_SIZE > count)
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rem = count - pos;
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ulong rem2 = rem*OVERSAMPLING;
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for (ulong i = 0; i < rem; i++) {
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buf[i][0] = in_L[i];
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buf[i][1] = in_R[i];
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}
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for (ulong i = 0; i < rem; i++) {
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over[i*2+0] = interpolate_a(hb_up, buf[i]);
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over[i*2+1] = interpolate_b(hb_up, buf[i]);
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}
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for (ulong i = 0; i < rem2; i++) {
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over[i] = process_one(over[i], data);
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}
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for (ulong i = 0; i < rem; i++) {
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decimate_a(hb_down, over[i*2+0]);
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buf[i] = decimate_b(hb_down, over[i*2+1]);
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}
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for (ulong i = 0; i < rem; i++) {
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out_L[i] = buf[i][0];
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out_R[i] = buf[i][1];
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}
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in_L += BLOCK_SIZE;
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in_R += BLOCK_SIZE;
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out_L += BLOCK_SIZE;
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out_R += BLOCK_SIZE;
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}
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}
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