crossover_dist_1404.xml

<?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 &lt;steve@plugin.org.uk&gt;"/>
    <meta name="copyright" value="GPL"/>
    <meta name="properties" value="HARD_RT_CAPABLE"/>
    <code><![CDATA[
      #include "ladspa-util.h"
    ]]></code>
  </global>

  <plugin label="crossoverDist" id="1404" class="DistortionPlugin">
    <name>Crossover distortion</name>
    <p>This is a simulation of the distortion that happens in class B and AB power amps when the signal crosses 0.</p>
    <p>For class B simulations the smooth value should be set to about 0.3 +/- 0.2 and for AB it should be set to near 1.0.</p>

    <callback event="run"><![CDATA[
      unsigned long pos;
      float sig;
      const float fade = fabs(amp * smooth) + 0.0001;

      for (pos = 0; pos < sample_count; pos++) {
	sig = fabs(input[pos]) - amp;

        if (sig < 0.0f) {
          sig *= (1.0f + sig/fade) * smooth;
        }

	if (input[pos] < 0.0f) {
	  buffer_write(output[pos], -sig);
        } else {
	  buffer_write(output[pos], sig);
        }
      }
    ]]></callback>

    <port label="amp" dir="input" type="control" hint="default_minimum">
      <name>Crossover amplitude</name>
      <p>Controls the point at which the output signal becomes linear.</p>
      <range min="0" max="0.1"/>
    </port>

    <port label="smooth" dir="input" type="control" hint="default_maximum">
      <name>Smoothing</name>
      <p>Controls degree of smoothing of the crossover point.</p>
      <range min="0" max="1"/>
    </port>

    <port label="input" dir="input" type="audio">
      <name>Input</name>
    </port>

    <port label="output" dir="output" type="audio">
      <name>Output</name>
    </port>
  </plugin>
</ladspa>