alpass.xml


<refentry id="alpass">
<indexterm id="IndexAlpass"><primary>alpass</primary></indexterm>
  <refentryinfo><title>Signal Modifiers:Reverberation</title></refentryinfo>
  <refmeta>
    <refentrytitle>alpass</refentrytitle>
  </refmeta>


 
  <refnamediv>
    <refname>alpass</refname>
    <refpurpose>
      Reverberates an input signal with a flat frequency response.
          </refpurpose>
  </refnamediv>
 
  <refsect1>
    <title>Description</title>
    <para>
      Reverberates an input signal with a flat frequency response.
    </para>
  </refsect1>
 
  <refsect1>
    <title>Syntax</title>
    <synopsis>ares <command>alpass</command> asig, xrvt, ilpt [, iskip] [, insmps]</synopsis>
  </refsect1>
 
  <refsect1>
    <title>Initialization</title>
    <para>
      <emphasis>ilpt</emphasis> -- loop time in seconds, which determines the <quote>echo density</quote> of the reverberation. This in turn characterizes the <quote>color</quote> of the filter whose frequency response curve will contain <emphasis>ilpt</emphasis> * <emphasis>sr</emphasis>/2 peaks spaced evenly between 0 and <emphasis>sr</emphasis>/2 (the Nyquist frequency). Loop time can be as large as available memory will permit. The space required for an <emphasis>n</emphasis> second loop is 4<emphasis>n</emphasis>*<emphasis>sr</emphasis> bytes. The delay space is allocated and returned as in <link linkend="delay"><citetitle>delay</citetitle></link>.
    </para>

    <para>
      <emphasis>iskip</emphasis> (optional, default=0) -- initial disposition of delay-loop data space (cf. <link linkend="reson"><citetitle>reson</citetitle></link>). The default value is 0.
    </para>

    <para>
      <emphasis>insmps</emphasis> (optional, default=0) -- delay amount, as a number of samples.
    </para>
  </refsect1>
 
  <refsect1>
    <title>Performance</title>
    <para>
      <emphasis>xrvt</emphasis> -- the reverberation time (defined as the time in seconds for a signal to decay to 1/1000, or 60dB down from its original amplitude).
    </para>

    <para>
      This filter reiterates the input with an echo density determined by loop time <emphasis>ilpt</emphasis>. The attenuation rate is independent and is determined by <emphasis>xrvt</emphasis>, the reverberation time (defined as the time in seconds for a signal to decay to 1/1000, or 60dB down from its original amplitude). Output will begin to appear immediately.
    </para>
  </refsect1>
 
  <refsect1>
    <title>Examples</title>
    <para>
      Here is an example of the alpass opcode. It uses the file <ulink url="examples/alpass.csd"><citetitle>alpass.csd</citetitle></ulink>.

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

        

        <para>See the sections <link linkend="UsingRealTime"><citetitle>Real-time Audio</citetitle></link> and <link linkend="CommandFlags"><citetitle>Command Line Flags</citetitle></link> for more information on using command line flags.</para>
          <xi:include href="examples-xml/alpass.csd.xml" xmlns:xi="http://www.w3.org/2001/XInclude"/>
      </example>
    </para>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para>
      <link linkend="comb"><citetitle>comb</citetitle></link>, 
      <link linkend="reverb"><citetitle>reverb</citetitle></link>, 
      <link linkend="valpass"><citetitle>valpass</citetitle></link>, 
      <link linkend="vcomb"><citetitle>vcomb</citetitle></link>
    </para>
  </refsect1>

  <refsect1>
    <title>Credits</title>
    <!-- <para> -->
    <!--   <simplelist> -->
    <!--     <member>Author: William <quote>Pete</quote> Moss (<emphasis>vcomb</emphasis> and <emphasis>valpass</emphasis>)</member> -->
    <!--     <member>University of Texas at Austin</member> -->
    <!--     <member>Austin, Texas USA</member> -->
    <!--     <member>January 2002</member> -->
    <!--   </simplelist> -->
    <!-- </para> -->
    <para>Audio rate parameter introduced in version 6.02</para>
    <para>November 2013.</para>
  </refsect1>
</refentry>