1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
|
/*
ZynAddSubFX - a software synthesizer
SVFilter.C - Several state-variable filters
Copyright (C) 2002-2005 Nasca Octavian Paul
Author: Nasca Octavian Paul
This program is free software; you can redistribute it and/or modify
it under the terms of version 2 of the GNU General Public License
as published by the Free Software Foundation.
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 (version 2) for more details.
You should have received a copy of the GNU General Public License (version 2)
along with this program; if not, write to the Free Software Foundation,
Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <math.h>
#include <stdio.h>
#include "SVFilter.h"
SVFilter::SVFilter(unsigned char Ftype,REALTYPE Ffreq, REALTYPE Fq,unsigned char Fstages){
stages=Fstages;
type=Ftype;
freq=Ffreq;
q=Fq;
gain=1.0;
outgain=1.0;
needsinterpolation=0;
firsttime=1;
if (stages>=MAX_FILTER_STAGES) stages=MAX_FILTER_STAGES;
cleanup();
setfreq_and_q(Ffreq,Fq);
};
SVFilter::~SVFilter(){
};
void SVFilter::cleanup(){
for (int i=0;i<MAX_FILTER_STAGES+1;i++){
st[i].low=0.0;st[i].high=0.0;
st[i].band=0.0;st[i].notch=0.0;
};
oldabovenq=0;
abovenq=0;
};
void SVFilter::computefiltercoefs(){
par.f=freq / SAMPLE_RATE*4.0;
if (par.f>0.99999) par.f=0.99999;
par.q=1.0-atan(sqrt(q))*2.0/PI;
par.q=pow(par.q,1.0/(stages+1));
par.q_sqrt=sqrt(par.q);
};
void SVFilter::setfreq(REALTYPE frequency){
if (frequency<0.1) frequency=0.1;
REALTYPE rap=freq/frequency;if (rap<1.0) rap=1.0/rap;
oldabovenq=abovenq;abovenq=frequency>(SAMPLE_RATE/2-500.0);
int nyquistthresh=(abovenq^oldabovenq);
if ((rap>3.0)||(nyquistthresh!=0)){//if the frequency is changed fast, it needs interpolation (now, filter and coeficients backup)
if (firsttime==0) needsinterpolation=1;
ipar=par;
};
freq=frequency;
computefiltercoefs();
firsttime=0;
};
void SVFilter::setfreq_and_q(REALTYPE frequency,REALTYPE q_){
q=q_;
setfreq(frequency);
};
void SVFilter::setq(REALTYPE q_){
q=q_;
computefiltercoefs();
};
void SVFilter::settype(int type_){
type=type_;
computefiltercoefs();
};
void SVFilter::setgain(REALTYPE dBgain){
gain=dB2rap(dBgain);
computefiltercoefs();
};
void SVFilter::setstages(int stages_){
if (stages_>=MAX_FILTER_STAGES) stages_=MAX_FILTER_STAGES-1;
stages=stages_;
cleanup();
computefiltercoefs();
};
void SVFilter::singlefilterout(REALTYPE *smp,fstage &x,parameters &par){
int i;
REALTYPE *out=NULL;
switch(type){
case 0: out=&x.low;break;
case 1: out=&x.high;break;
case 2: out=&x.band;break;
case 3: out=&x.notch;break;
};
for (i=0;i<SOUND_BUFFER_SIZE;i++){
x.low = x.low + par.f * x.band;
x.high = par.q_sqrt * smp[i] - x.low - par.q*x.band;
x.band = par.f * x.high + x.band;
x.notch = x.high + x.low;
smp[i]= *out;
};
};
void SVFilter::filterout(REALTYPE *smp){
int i;
REALTYPE *ismp=NULL;
if (needsinterpolation!=0){
ismp=new REALTYPE[SOUND_BUFFER_SIZE];
for (i=0;i<SOUND_BUFFER_SIZE;i++) ismp[i]=smp[i];
for (i=0;i<stages+1;i++) singlefilterout(ismp,st[i],ipar);
};
for (i=0;i<stages+1;i++) singlefilterout(smp,st[i],par);
if (needsinterpolation!=0){
for (i=0;i<SOUND_BUFFER_SIZE;i++) {
REALTYPE x=i/(REALTYPE) SOUND_BUFFER_SIZE;
smp[i]=ismp[i]*(1.0-x)+smp[i]*x;
};
delete (ismp);
needsinterpolation=0;
};
for (i=0;i<SOUND_BUFFER_SIZE;i++) smp[i]*=outgain;
};
|
