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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 "util/db.h"
#include "util/rms.h"
#define A_TBL 256
]]></code>
</global>
<plugin label="sc1" id="1425" class="CompressorPlugin">
<name>SC1</name>
<p>An high quality, reasonably low CPU cost RMS compressor designed for musical work.</p>
<p>It has controls for the compression point, compression ratio and knee softness.</p>
<callback event="instantiate"><![CDATA[
unsigned int i;
float sample_rate = (float)s_rate;
rms = rms_env_new();
sum = 0.0f;
amp = 0.0f;
gain = 0.0f;
gain_t = 0.0f;
env = 0.0f;
count = 0;
as = malloc(A_TBL * sizeof(float));
as[0] = 1.0f;
for (i=1; i<A_TBL; i++) {
as[i] = expf(-1.0f / (sample_rate * (float)i / (float)A_TBL));
}
db_init();
]]></callback>
<callback event="cleanup"><![CDATA[
rms_env_free(plugin_data->rms);
free(plugin_data->as);
]]></callback>
<callback event="run"><![CDATA[
unsigned long pos;
const float ga = as[f_round(attack * 0.001f * (float)(A_TBL-1))];
const float gr = as[f_round(release * 0.001f * (float)(A_TBL-1))];
const float rs = (ratio - 1.0f) / ratio;
const float mug = db2lin(makeup_gain);
const float knee_min = db2lin(threshold - knee);
const float knee_max = db2lin(threshold + knee);
const float ef_a = ga * 0.25f;
const float ef_ai = 1.0f - ef_a;
for (pos = 0; pos < sample_count; pos++) {
sum += input[pos] * input[pos];
if (amp > env) {
env = env * ga + amp * (1.0f - ga);
} else {
env = env * gr + amp * (1.0f - gr);
}
if (count++ % 4 == 3) {
amp = rms_env_process(rms, sum * 0.25f);
sum = 0.0f;
if (env <= knee_min) {
gain_t = 1.0f;
} else if (env < knee_max) {
const float x = -(threshold - knee - lin2db(env)) / knee;
gain_t = db2lin(-knee * rs * x * x * 0.25f);
} else {
gain_t = db2lin((threshold - lin2db(env)) * rs);
}
}
gain = gain * ef_a + gain_t * ef_ai;
buffer_write(output[pos], input[pos] * gain * mug);
}
plugin_data->sum = sum;
plugin_data->amp = amp;
plugin_data->gain = gain;
plugin_data->gain_t = gain_t;
plugin_data->env = env;
plugin_data->count = count;
]]></callback>
<port label="attack" dir="input" type="control" hint="default_low">
<name>Attack time (ms)</name>
<p>The attack time in milliseconds.</p>
<range min="2" max="400"/>
</port>
<port label="release" dir="input" type="control" hint="default_middle">
<name>Release time (ms)</name>
<p>The release time in milliseconds.</p>
<range min="2" max="800"/>
</port>
<port label="threshold" dir="input" type="control" hint="default_maximum">
<name>Threshold level (dB)</name>
<p>The point at which the compressor will start to kick in.</p>
<range min="-30" max="0"/>
</port>
<port label="ratio" dir="input" type="control" hint="default_1">
<name>Ratio (1:n)</name>
<p>The gain reduction ratio used when the signal level exceeds the threshold.</p>
<range min="1" max="10"/>
</port>
<port label="knee" dir="input" type="control" hint="default_low">
<name>Knee radius (dB)</name>
<p>The distance from the threshold where the knee curve starts.</p>
<range min="1" max="10"/>
</port>
<port label="makeup_gain" dir="input" type="control" hint="default_0">
<name>Makeup gain (dB)</name>
<p>Controls the gain of the makeup input signal in dB's.</p>
<range min="0" max="+24"/>
</port>
<port label="input" dir="input" type="audio">
<name>Input</name>
</port>
<port label="output" dir="output" type="audio">
<name>Output</name>
</port>
<instance-data label="rms" type="rms_env *" />
<instance-data label="as" type="float *" />
<instance-data label="sum" type="float" />
<instance-data label="amp" type="float" />
<instance-data label="gain" type="float" />
<instance-data label="gain_t" type="float" />
<instance-data label="env" type="float" />
<instance-data label="count" type="unsigned int" />
</plugin>
</ladspa>
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