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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="Joern Nettingsmeier <nettings@folkwang-hochschule.de>"/>
<meta name="copyright" value="GPL"/>
<meta name="properties" value="HARD_RT_CAPABLE"/>
<code><![CDATA[
/*
thanks to Steve Harris for walking me through my first plugin !
*/
#include "ladspa-util.h"
/* we use sin/cos panning and start at pi/4. this is the correction factor
to bring the signal back to unity gain in neutral position.
it should be 1/x : sin(x) = cos(x) (~1.41421...). but since we are using an
approximation of sin/cos, we take its equal gain point, which leads to 1.3333...
*/
#define EQUALGAINPOINT_OFFSET 128.0f
#define EQUALGAINPOINT_TO_UNITY 4.0f / 3.0f
#define BITSPERCYCLE 10 /* resolution of the width parameter for */
#define BITSPERQUARTER (BITSPERCYCLE-2) /* one cycle (0-2pi) */
/* borrowed code: http://www.dspguru.com/comp.dsp/tricks/alg/sincos.htm
i'm using a constant of 0.75, which makes the calculations simpler and does
not yield discontinuities.
author: Olli Niemitalo (oniemita@mail.student.oulu.fi)
*/
static inline void sin_cos_approx(int phasein, float *vsin, float *vcos) {
// Modulo phase into quarter, convert to float 0..1
float modphase = (phasein & ((1<<BITSPERQUARTER) - 1))
* 1.0f / (1<<BITSPERQUARTER);
// Extract quarter bits
int quarter = phasein & (3<<BITSPERQUARTER);
// Recognize quarter
if (!quarter) {
// First quarter, angle = 0 .. pi/2
float x = modphase - 0.5f;
float temp = 0.75f - x * x;
*vsin = temp + x;
*vcos = temp - x;
} else if (quarter == 1<<BITSPERQUARTER) {
// Second quarter, angle = pi/2 .. pi
float x = 0.5f - modphase;
float temp = 0.75f - x*x;
*vsin = x + temp;
*vcos = x - temp;
} else if (quarter == 2<<BITSPERQUARTER) {
// Third quarter, angle = pi .. 1.5pi
float x = modphase - 0.5f;
float temp = x*x - 0.75f;
*vsin = temp - x;
*vcos = temp + x;
} else {
// Fourth quarter, angle = 1.5pi..2pi
float x = modphase - 0.5f;
float temp = 0.75f - x*x;
*vsin = x - temp;
*vcos = x + temp;
}
}
]]></code>
</global>
<plugin label="matrixSpatialiser" id="1422" class="UtilityPlugin">
<name>Matrix Spatialiser</name>
<p><![CDATA[
A simple spatializer that lets you control the width of a stereo signal.
We convert it into a MS (mid/side) signal, manipulate the gain coefficients
with a constant-power panning function, and reconvert to left/right stereo.
$mid = (i_left + i_right) / 2$
$side = (i_left - i_right) / 2$
$width = (-pi/4)..0..(pi/4)$
$o_left = mid * cos(width + pi/4)$
$o_right = side * sin(width + pi/4)$
{\small shifted by pi/4, so that 0 is neutral.}
]]></p>
<callback event="instantiate"><![CDATA[
current_m_gain = 0.0f;
current_s_gain = 0.0f;
]]></callback>
<callback event="activate"><![CDATA[
sin_cos_approx(EQUALGAINPOINT_OFFSET, ¤t_s_gain, ¤t_m_gain);
current_m_gain *= EQUALGAINPOINT_TO_UNITY; /* normalize the neutral */
current_s_gain *= EQUALGAINPOINT_TO_UNITY; /* setting to unity gain. */
]]></callback>
<callback event="run"><![CDATA[
unsigned long pos;
LADSPA_Data mid, side;
LADSPA_Data m_gain, s_gain;
int width_ = f_round(width + EQUALGAINPOINT_OFFSET);
/* smoothen the gain changes. to spread the curve over the entire
buffer length (i.e.#sample_count samples), make lp dependent on
sample_count.
*/
const float lp = 7.0f / (float) sample_count; /* value found by experiment */
const float lp_i = 1.0f - lp;
/* do approximately the same as
s_gain = sin(width); m_gain = cos(width);
but a lot faster:
*/
sin_cos_approx(width_, &s_gain, &m_gain);
m_gain *= EQUALGAINPOINT_TO_UNITY; /* normalize the neutral */
s_gain *= EQUALGAINPOINT_TO_UNITY; /* setting to unity gain. */
#ifdef DEBUG
/* do a "hardware bypass" if width == 0 */
/* no smoothing here */
if (width_ == 128) {
for (pos = 0; pos < sample_count; pos++) {
buffer_write(o_left[pos], i_left[pos]);
buffer_write(o_right[pos], i_right[pos]);
}
} else
#endif
for (pos = 0; pos < sample_count; pos++) {
current_m_gain = current_m_gain * lp_i + m_gain * lp;
current_s_gain = current_s_gain * lp_i + s_gain * lp;
mid = (i_left[pos] + i_right[pos]) * 0.5f * current_m_gain;
side = (i_left[pos] - i_right[pos]) * 0.5f * current_s_gain;
buffer_write(o_left[pos], mid + side);
buffer_write(o_right[pos], mid - side);
}
plugin_data->current_m_gain = current_m_gain;
plugin_data->current_s_gain = current_s_gain;
]]></callback>
<port label="i_left" dir="input" type="audio">
<name>Input L</name>
</port>
<port label="i_right" dir="input" type="audio">
<name>Input R</name>
</port>
<port label="width" dir="input" type="control" hint="integer,default_0">
<name>Width</name>
<range min="-512" max="512"/>
<p><![CDATA[
0 is neutral (unmodified signal)
+ 128 is side only (=very wide)
- 128 is mid only (=mono)
]]></p>
</port>
<port label="o_left" dir="output" type="audio">
<name>Output L</name>
</port>
<port label="o_right" dir="output" type="audio">
<name>Output R</name>
</port>
<instance-data label="current_m_gain" type="LADSPA_Data" />
<instance-data label="current_s_gain" type="LADSPA_Data" />
</plugin>
</ladspa>
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