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/* Linear Predictive Coding - PARCOR and residual generation
* Copyright (C) 2005 Nicolas Chetry <okin@altern.org>
* and Edward Kelly <morph_2016@yahoo.co.uk>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "m_pd.h"
#include <math.h>
#define MAXPOLES 100
static t_class *lpc_tilde_class;
typedef struct _lpc_schur
{
t_float *c_input, *c_residual;
/* just so we don't get clicks */
t_atom x_last_parcors[MAXPOLES];
t_atom x_parcors[MAXPOLES];
} t_lpc_schur;
typedef struct _lpc_tilde
{
t_object x_obj;
t_float f_dummy;
t_float x_order, x_lastorder;
t_outlet *parcor_list;
t_lpc_schur x_schur;
} t_lpc_tilde;
t_int *lpc_tilde_perform(t_int *w)
{
t_lpc_tilde *x = (t_lpc_tilde *)(w[1]);
t_lpc_schur *schur = (t_lpc_schur *)(w[2]);
int n = (int)(w[3]);
t_float *in = schur->c_input;
t_float *res = schur->c_residual;
// t_float *parcors = schur->PARCORS;
// t_float *acf = schur->ACF;
// t_float *k = schur->K;
// t_float *p = schur->P;
// t_float *r = schur->r;
t_int ord = (int)x->x_order;
t_int l_ord = (int)x->x_lastorder;
// t_float parcors[ord];
float acf[ord+1];
float k[ord+1];
float p[ord+1];
float r[ord+1];
float mem[ord];
int i, j, bid, y, z;
int g, h;
float tmp, temp, sav, di;
float parcor_1;
for (i=0; i<ord; i++)
{
SETFLOAT (&schur->x_parcors[i],0);
mem[i] = 0.0;
}
for (j=0; j<=ord; j++)
{
acf[j] = 0;
for (i=j; i<n; i++)
{
acf[j] += in[i]*in[i-j];
}
}
if (acf[0] == 0)
{
for (i=0; i<ord; i++)
{
SETFLOAT (&schur->x_parcors[i],0);
}
}
for (i=0; i<=ord; i++)
{
p[i]=acf[i];
if (i > 0 && i < ord)
{
k[ord+1-i] = acf[i];
}
}
/* Schurr recursion */
for (y=1; y<=ord; y++)
{
if (p[0] < fabs (p[1]))
{
for (i=y; i<=ord; i++)
{
r[i] = 0;
}
for (bid=1; bid <=ord; bid++)
{
SETFLOAT (&schur->x_parcors[bid-1],r[bid]);
// x->x_parcors[bid-1] = r[bid];
}
}
r[y] = fabs(p[1])/p[0];
if (p[1] >0)
{
r[y] = -1.*r[y];
}
if (y==ord)
{
for (bid=1; bid <=ord; bid++)
{
SETFLOAT (&schur->x_parcors[bid-1],r[bid]);
// x->x_parcors[bid-1] = r[bid];
}
}
p[0] += p[1]*r[y];
for (z=1; z <=ord-y; z++)
{
p[z] = p[z+1] + k[ord+1-z]*r[y];
k[ord+1-z] += p[z+1] * r[y];
}
}
for (bid=1; bid <=ord; bid++)
{
SETFLOAT (&schur->x_parcors[bid-1],r[bid]);
}
parcor_1 = atom_getfloatarg(0,ord,schur->x_parcors); /* in order to avoid nil coefficients */
if (parcor_1 > 1e-5 || parcor_1 < -1e-5)
{
outlet_list(x->parcor_list,gensym("list"),ord,schur->x_parcors);
/* Analysis FIR lattice filtering */
for (g=0; g<n; g++)
{
/* Analysis - Lattice structure */
sav = di = in[g];
for (i=0; i<ord; i++)
{
t_float parcor = atom_getfloatarg (i,ord,schur->x_parcors);
SETFLOAT (&schur->x_last_parcors[i],parcor);
x->x_lastorder = ord;
temp = mem[i] + parcor*di;
di += parcor*mem[i];
mem[i] = sav;
sav = temp;
}
res[g] = di;
} /* next g */
}
else
{
outlet_list(x->parcor_list,gensym("list"),l_ord,schur->x_last_parcors);
for (g=0; g<n; g++)
{
res[g] = 0;
}
}
return(w+4);
}
void *lpc_tilde_dsp(t_lpc_tilde *x, t_signal **sp)
{
x->x_schur.c_input = sp[0]->s_vec;
x->x_schur.c_residual = sp[1]->s_vec;
dsp_add(lpc_tilde_perform, 3, x, &x->x_schur, sp[0]->s_n);
return (void *)x;
}
void *lpc_tilde_new(t_floatarg f)
{
t_lpc_tilde *x = (t_lpc_tilde *)pd_new(lpc_tilde_class);
x->x_order = f >= 1 ? (int)f : 5;
floatinlet_new(&x->x_obj,&x->x_order);
outlet_new(&x->x_obj, &s_signal);
x->parcor_list = outlet_new(&x->x_obj, &s_list);
return (void *)x;
}
void lpc_tilde_setup(void)
{
lpc_tilde_class = class_new(gensym("lpc~"), (t_newmethod)lpc_tilde_new, 0, sizeof(t_lpc_tilde), CLASS_DEFAULT, A_DEFFLOAT, 0);
post("\n. . Linear Predictive Coding. . . . . . . .");
post(". . PARCOR coefficients from input. . . . .");
post(". . by Nicolas Chetry <okin@altern.org> . .");
post(". & Edward Kelly <morph_2016@yahoo.co.uk> .");
class_addmethod(lpc_tilde_class, (t_method)lpc_tilde_dsp, gensym("dsp"), 0);
CLASS_MAINSIGNALIN(lpc_tilde_class, t_lpc_tilde, f_dummy);
}
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