<!-- Converted to DocBook/SGML by Kevin Conder -->
<refentry id="follow">
  <refmeta>
    <refentrytitle>follow</refentrytitle>
  </refmeta>
 
  <refnamediv>
    <refname>follow</refname>

    <refpurpose>
      Envelope follower unit generator.
      <indexterm id="IndexFollow"><primary>follow</primary></indexterm>
    </refpurpose>
  </refnamediv>
 
  <refsect1>
    <title>Description</title>
    <para>
      Envelope follower unit generator.
    </para>
  </refsect1>
 
  <refsect1>
    <title>Syntax</title>
    <synopsis>ar <command>follow</command> asig, idt</synopsis>
  </refsect1>
 
  <refsect1>
    <title>Initialization</title>
    <para>
<emphasis>idt</emphasis> -- This is the period, in seconds, that the average amplitude of <emphasis>asig</emphasis> is reported. If the frequency of <emphasis>asig</emphasis> is low then <emphasis>idt</emphasis> must be large (more than half the period of <emphasis>asig</emphasis> )
    </para>
  </refsect1>
 
  <refsect1>
    <title>Performance</title>
    <para>
      <emphasis>asig</emphasis> -- This is the signal from which to extract the envelope.
    </para>
  </refsect1>
 
  <refsect1>
    <title>Examples</title>
    <para>
      Here is an example of the follow opcode. It uses the files <ulink url="examples/follow.orc"><citetitle>follow.orc</citetitle></ulink>, <ulink url="examples/follow.sco"><citetitle>follow.sco</citetitle></ulink>, and <ulink url="examples/beats.wav"><citetitle>beats.wav</citetitle></ulink>.

      <example>
        <title>Example of the follow opcode.</title>

        <programlisting>
<inlinemediaobject>
            <imageobject>
              <imagedata fileref="examples/follow.orc" format="linespecific">
            </imageobject>
          </inlinemediaobject>
        </programlisting>

        <programlisting>
<inlinemediaobject>
            <imageobject>
              <imagedata fileref="examples/follow.sco" format="linespecific">
            </imageobject>
          </inlinemediaobject>
        </programlisting>
      </example>
    </para>

    <para>
      To avoid zipper noise, by discontinuities produced from complex envelope tracking, a lowpass filter could be used, to smooth the estimated envelope.
    </para>
  </refsect1>
 
  <refsect1>
    <title>Credits</title>
    <para>
      <simplelist>
        <member>Author: &nameparis;</member>
        <member>MIT, Cambridge</member>
        <member>1995</member>
      </simplelist>
    </para>
  </refsect1>
</refentry>
