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<?xml version="1.0" ?>
<!DOCTYPE ladspa SYSTEM "ladspa-swh.dtd">
<?xml-stylesheet href="ladspa.css" type="text/css" ?>
<ladspa>
<global>
<meta name="maker" value="Steve Harris <steve@plugin.org.uk>"/>
<meta name="copyright" value="GPL"/>
<meta name="properties" value="HARD_RT_CAPABLE"/>
<code><![CDATA[
#include "ladspa-util.h"
// Constants to match filter types
#define F_LP 1
#define F_HP 2
#define F_BP 3
#define F_BR 4
#define F_AP 5
// Number of filter oversamples
#define F_R 3
/* Structure to hold parameters for SV filter */
typedef struct {
float f; // 2.0*sin(PI*fs/(fc*r));
float q; // 2.0*cos(pow(q, 0.1)*PI*0.5);
float qnrm; // sqrt(m/2.0f+0.01f);
float h; // high pass output
float b; // band pass output
float l; // low pass output
float p; // peaking output (allpass with resonance)
float n; // notch output
float *op; // pointer to output value
} sv_filter;
/* Store data in SVF struct, takes the sampling frequency, cutoff frequency
and Q, and fills in the structure passed */
static inline void setup_svf(sv_filter *sv, float fs, float fc, float q, int t) {
sv->f = 2.0f * sin(M_PI * fc / (float)(fs * F_R));
sv->q = 2.0f * cos(pow(q, 0.1f) * M_PI * 0.5f);
sv->qnrm = sqrt(sv->q/2.0+0.01);
switch(t) {
case F_LP:
sv->op = &(sv->l);
break;
case F_HP:
sv->op = &(sv->h);
break;
case F_BP:
sv->op = &(sv->b);
break;
case F_BR:
sv->op = &(sv->n);
break;
default:
sv->op = &(sv->p);
}
}
/* Run one sample through the SV filter. Filter is by andy@vellocet */
static inline float run_svf(sv_filter *sv, float in) {
float out;
int i;
in = sv->qnrm * in ;
for (i=0; i < F_R; i++) {
// only needed for pentium chips
in = flush_to_zero(in);
sv->l = flush_to_zero(sv->l);
// very slight waveshape for extra stability
sv->b = sv->b - sv->b * sv->b * sv->b * 0.001f;
// regular state variable code here
// the notch and peaking outputs are optional
sv->h = in - sv->l - sv->q * sv->b;
sv->b = sv->b + sv->f * sv->h;
sv->l = sv->l + sv->f * sv->b;
sv->n = sv->l + sv->h;
sv->p = sv->l - sv->h;
out = *(sv->op);
in = out;
}
return out;
}
]]></code>
</global>
<plugin label="svf" id="1214" class="FilterPlugin">
<name>State Variable Filter</name>
<p>An oversampled state variable filter with a few tweaks</p>
<p>Quite a nice State Variable Filter, tends to be unstable with high resonance and Q values, but good when kept under control.</p>
<callback event="instantiate">
sample_rate = s_rate;
svf = calloc(1, sizeof(sv_filter));
</callback>
<callback event="activate">
setup_svf(svf, 0, 0, 0, 0);
</callback>
<callback event="cleanup">
free(plugin_data->svf);
</callback>
<callback event="run"><![CDATA[
long int pos;
setup_svf(svf, sample_rate, filt_freq, filt_q, f_round(filt_type));
for (pos = 0; pos < sample_count; pos++) {
buffer_write(output[pos], run_svf(svf, input[pos] + (svf->b * filt_res)));
}
]]></callback>
<port label="input" dir="input" type="audio">
<name>Input</name>
<range min="-1" max="1"/>
</port>
<port label="output" dir="output" type="audio">
<name>Output</name>
<range min="-1" max="1"/>
</port>
<port label="filt_type" dir="input" type="control" hint="integer,default_0">
<name>Filter type (0=none, 1=LP, 2=HP, 3=BP, 4=BR, 5=AP)</name>
<range min="0" max="5"/>
<p>Select between no filtering, low-pass, high-pass, band-pass, band-reject and all-pass.</p>
</port>
<port label="filt_freq" dir="input" type="control" hint="default_440">
<name>Filter freq</name>
<range min="0" max="6000"/>
<p>Cutoff frequency, beware of high values with low sample rates.</p>
</port>
<port label="filt_q" dir="input" type="control" hint="default_low">
<name>Filter Q</name>
<range min="0" max="1"/>
<p>The filters Q, or cutoff slope.</p>
</port>
<port label="filt_res" dir="input" type="control" hint="default_0">
<name>Filter resonance</name>
<range min="0" max="1"/>
<p>The filter's resonance, sort of separate from Q but very related (implemented with feedback).</p>
<p>Do not use with the bandpass mode.</p>
</port>
<instance-data label="sample_rate" type="int"/>
<instance-data label="svf" type="sv_filter *"/>
</plugin>
</ladspa>
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