analogue_osc_1416.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 <math.h>

      #include "ladspa-util.h"
      #include "util/blo.h"
    ]]></code>
  </global>

  <plugin label="analogueOsc" id="1416" class="OscillatorPlugin">
    <name>Analogue Oscillator</name>
    <p>This plugin simulates the output you get from an analogue synth's oscillators.</p>
    <p>You can get a reasonable emulation of a 303's square (for example) if you set the warmth to about 0.4 and the instability to about 0.05.</p>
    <p>The frequency is currently a control input, and there is no interpolation, so if your host is using large block size it will sound steppy.</p>
    <p>I'm unsure whether to convert this to an audio input or interpolate the control in.</p>

    <callback event="instantiate"><![CDATA[
      tables = blo_h_tables_new(512);
      osc = blo_h_new(tables, BLO_SINE, (float)s_rate);
      fs = (float)s_rate;
      itm1 = 0.0f;
      otm1 = 0.0f;
      otm2 = 0.0f;
      rnda = 43437;
      rndb = 111145;
    ]]></callback>

    <callback event="cleanup"><![CDATA[
      blo_h_tables_free(plugin_data->tables);
      blo_h_free(plugin_data->osc);
    ]]></callback>

    <callback event="run" unused-vars="tables"><![CDATA[
      unsigned long pos;
      LADSPA_Data x, y;
      const float q = warm - 0.999f;
      const float leak = 1.0f - warm * 0.02f;
      const unsigned int max_jump = (unsigned int)f_round(instab * 30000.0f) + 1;

      osc->wave = LIMIT(f_round(wave) - 1, 0, BLO_N_WAVES-1);
      osc->nyquist = fs * (0.47f - f_clamp(warm, 0.0f, 1.0f) * 0.41f);
      blo_hd_set_freq(osc, freq);

      for (pos = 0; pos < sample_count; pos++) {
	x = blo_hd_run_cub(osc);
        rnda += 432577;
        rnda *= 47;
	rndb += 7643113;
        rnda *= 59;
        osc->ph.all += (((rnda + rndb)/2) % max_jump) - max_jump/2;
        osc->ph.all &= osc->ph_mask;
	y = (x - q) / (1.0f - f_exp(-1.2f * (x - q))) +
              q / (1.0f - f_exp(1.2f * q));
	/* Catch the case where x ~= q */
	if (isnan(y) || fabs(y) > 1.0f) {
		y = 0.83333f + q / (1.0f - f_exp(1.2f * q));
	}
	otm2 = otm1;
        otm1 = leak * otm1 + y - itm1;
        itm1 = y;

        buffer_write(output[pos], (otm1 + otm2) * 0.5f);
      }

      plugin_data->itm1 = itm1;
      plugin_data->otm1 = otm1;
      plugin_data->otm2 = otm2;
      plugin_data->rnda = rnda;
      plugin_data->rndb = rndb;
    ]]></callback>

    <port label="wave" dir="input" type="control" hint="integer,default_1">
      <name>Waveform (1=sin, 2=tri, 3=squ, 4=saw)</name>
      <p><![CDATA[
	The basic shape of the waveform is selected using this control:

	\begin{tabular}{|r|l|}
	\hline
	Value & Waveform \\
	\hline \hline
	1 & Sine \\
	2 & Triangle \\
	3 & Square \\
	4 & Saw \\
        \hline
	\end{tabular}
      ]]></p>
      <range min="1" max="BLO_N_WAVES"/>
    </port>

    <port label="freq" dir="input" type="control" hint="sample_rate,default_440,logarithmic">
      <name>Frequency (Hz)</name>
      <p>The frequency of the output (Hz).</p>
      <range min="0.000001" max="0.499"/>
    </port>

    <port label="warm" dir="input" type="control" hint="default_0">
      <name>Warmth</name>
      <p>The degree of softening that is applied to the generated waveform, reduces the number of harmonics in the output.</p>
      <range min="0" max="1"/>
    </port>

    <port label="instab" dir="input" type="control" hint="default_0">
      <name>Instability</name>
      <p>The degree of pitch instability of the output. Turning this too high with square and saw waves will produce an annoying jittery sound, I want to fix this but it is tricky.</p>
      <range min="0" max="1"/>
    </port>

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

    <instance-data label="tables" type="blo_h_tables *" />
    <instance-data label="osc" type="blo_h_osc *" />
    <instance-data label="fs" type="float" />
    <instance-data label="itm1" type="float" />
    <instance-data label="otm1" type="float" />
    <instance-data label="otm2" type="float" />
    <instance-data label="rnda" type="unsigned int" />
    <instance-data label="rndb" type="unsigned int" />
  </plugin>
</ladspa>