foldover_1213.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"/>
  </global>

  <plugin label="foldover" id="1213" class="DistortionPlugin">
    <name>Foldover distortion</name>
    <p>Uses a sinwave approximation to simulate valve style foldover distortion.</p>
    <p>Probably should have a DC offset remover on the output, but it's not always necessary.</p>

    <callback event="run"><![CDATA[
      unsigned long pos;
      float x;
      const float drive = drive_p + 1.0f;

      for (pos = 0; pos < sample_count; pos++) {
	x = input[pos] * drive + push;
        buffer_write(output[pos], 1.5f * x - 0.5f * x * x * x);
      }
    ]]></callback>

    <port label="drive_p" dir="input" type="control" hint="default_0">
      <name>Drive</name>
      <range min="0" max="1"/>
      <p>Controls the degree of distortion.</p>
    </port>

    <port label="push" dir="input" type="control" hint="default_0">
      <name>Skew</name>
      <range min="0" max="1"/>
      <p>Controls the asymmetry of the waveform.</p>
    </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>