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rbj_highpass.c
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rbj_highpass.c
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#include <ladspa.h>
#define _GNU_SOURCE
#include <math.h>
#include <stdlib.h>
/* (b0/a0) + (b1/a0)*z^-1 + (b2/a0)*z^-2
* H(z) = ---------------------------------------
* 1 + (a1/a0)*z^-1 + (a2/a0)*z^-2
*
* b0 = (1 + cos(omega))/2
* b1 =-(1 + cos(omega))
* b2 = (1 + cos(omega))/2
* a0 = 1 + alpha
* a1 = -2 cos(omega)
* a2 = 1 - alpha
*
* omega = 2 * pi * fc / fs
* alpha = sin(omega) * sinh( log(2)/2 * bw * omega / sin(omega) )
* = sin(omega) / (2*Q)
*/
enum {
PORT_IN,
PORT_OUT,
PORT_FREQUENCY,
PORT_Q,
PORT_GAIN,
PORT_NPORTS
};
typedef struct {
unsigned long m_sample_rate;
LADSPA_Data *m_pport[PORT_NPORTS];
LADSPA_Data m_z1;
LADSPA_Data m_z2;
LADSPA_Data m_log2d2;
} Highpass_Data;
static LADSPA_Handle Highpass_instantiate(
const struct _LADSPA_Descriptor *p_pDescriptor,
unsigned long p_sample_rate ){
Highpass_Data *l_pHighpass = malloc( sizeof(Highpass_Data) );
if( l_pHighpass ){
l_pHighpass->m_sample_rate = p_sample_rate;
l_pHighpass->m_z1 = 0.0;
l_pHighpass->m_z2 = 0.0;
l_pHighpass->m_log2d2 = logf(2.0)/2.0;
}
return (LADSPA_Handle)l_pHighpass;
}
static void Highpass_connect_port(
LADSPA_Handle p_pInstance,
unsigned long p_port,
LADSPA_Data *p_pdata)
{
Highpass_Data *l_pHighpass = (Highpass_Data*)p_pInstance;
l_pHighpass->m_pport[p_port] = p_pdata;
}
static void Highpass_run(
LADSPA_Handle p_pInstance,
unsigned long p_sample_count )
{
Highpass_Data *l_pHighpass = (Highpass_Data*)p_pInstance;
unsigned long l_sample;
LADSPA_Data *l_psrc = l_pHighpass->m_pport[PORT_IN];
LADSPA_Data *l_pdst = l_pHighpass->m_pport[PORT_OUT];
LADSPA_Data l_omega = 2.0f*(float)M_PI* *l_pHighpass->m_pport[PORT_FREQUENCY] /
l_pHighpass->m_sample_rate;
LADSPA_Data l_sin_omega;// = sinf( l_omega );
LADSPA_Data l_cos_omega;// = cosf( l_omega );
sincosf(l_omega, &l_sin_omega, &l_cos_omega);
LADSPA_Data l_alpha = l_sin_omega /( 2.0F * *l_pHighpass->m_pport[PORT_Q]);
LADSPA_Data l_a0 = 1.0f + l_alpha;
LADSPA_Data l_a1 =-2.0f * l_cos_omega / l_a0;
LADSPA_Data l_a2 = (1.0f - l_alpha) / l_a0;
LADSPA_Data l_temp = (1.0f + l_cos_omega)/l_a0;
LADSPA_Data l_b0 = l_temp/2.0f;
LADSPA_Data l_b1 =-l_temp;
LADSPA_Data l_b2 = l_b0;
LADSPA_Data l_G = powf(10.0F, *l_pHighpass->m_pport[PORT_GAIN] / 20.0f );
l_sample = p_sample_count;
while(l_sample){
LADSPA_Data l_m = *(l_psrc++) - l_a1*l_pHighpass->m_z1 - l_a2*l_pHighpass->m_z2;
*(l_pdst++) = l_G*(l_m*l_b0 + l_pHighpass->m_z1*l_b1 + l_pHighpass->m_z2*l_b2);
l_pHighpass->m_z2 = l_pHighpass->m_z1;
l_pHighpass->m_z1 = l_m;
l_sample--;
}
}
static void Highpass_cleanup( LADSPA_Handle p_pInstance )
{
free( p_pInstance );
}
static LADSPA_PortDescriptor Highpass_PortDescriptors[]=
{
LADSPA_PORT_INPUT|LADSPA_PORT_AUDIO,
LADSPA_PORT_OUTPUT|LADSPA_PORT_AUDIO,
LADSPA_PORT_INPUT|LADSPA_PORT_CONTROL,
LADSPA_PORT_INPUT|LADSPA_PORT_CONTROL,
LADSPA_PORT_INPUT|LADSPA_PORT_CONTROL
};
static const char *Highpass_PortNames[]=
{
"Input",
"Output",
"Frequency",
"Q",
"Gain"
};
static LADSPA_PortRangeHint Highpass_PortRangeHints[]=
{
{0,0,0},
{0,0,0},
{LADSPA_HINT_BOUNDED_BELOW|LADSPA_HINT_BOUNDED_ABOVE|
LADSPA_HINT_LOGARITHMIC|LADSPA_HINT_DEFAULT_MIDDLE,
10,15000},
{LADSPA_HINT_BOUNDED_BELOW|LADSPA_HINT_BOUNDED_ABOVE|
LADSPA_HINT_DEFAULT_MIDDLE,
0.707,100},
{LADSPA_HINT_BOUNDED_BELOW|LADSPA_HINT_BOUNDED_ABOVE|
LADSPA_HINT_DEFAULT_0,
-60,24}
};
LADSPA_Descriptor RBJHighpassQ_Descriptor=
{
5817,
"RBJ_highpass_Q",
LADSPA_PROPERTY_HARD_RT_CAPABLE,
"Highpass RBJ(Q)",
"Timothy William Krause",
"None",
PORT_NPORTS,
Highpass_PortDescriptors,
Highpass_PortNames,
Highpass_PortRangeHints,
NULL,
Highpass_instantiate,
Highpass_connect_port,
NULL,
Highpass_run,
NULL,
NULL,
NULL,
Highpass_cleanup
};