allpole.xml

<refentry id="allpole">
<indexterm id="IndexAllpole"><primary>allpole</primary></indexterm>
  <refentryinfo><title>Spectral Processing:LPC</title></refentryinfo>
  <refmeta>
    <refentrytitle>allpole</refentrytitle>
  </refmeta>

  <refnamediv>
    <refname>allpole</refname>
    <refpurpose>
    Allpole filter implementation using direct convolution.
    </refpurpose>
  </refnamediv>
 
  <refsect1>
    <title>Description</title>
    <para>
     This opcode implements an allpole filter using direct
     convolution.
    </para>
  </refsect1>
 
  <refsect1>
    <title>Syntax</title>
    <synopsis>ares <command>allpole</command> asig, kCoef[]</synopsis>

  </refsect1>
  
  <refsect1>
    <title>Performance</title>
    <para>
      <emphasis>kCoef[]</emphasis> -- all-pole filter coefficients
      (iord-size array)
    </para>
        <para>
      <emphasis>asig</emphasis> -- audio input
        </para>

     <para>
      <emphasis>ares</emphasis> -- audio output
    </para>

  </refsect1>

    <refsect1>
   <para>
        This opcode is part of a suite of streaming linear prediction
        opcodes. It implements an allpole filter using coefficients
        passed to it via a k-rate array. The filter length is
        determined by the array size
    </para>
    
    <para>
      The typical application is compute the coefficients via some
      method and then pass these to the opcode. The set of
      coefficients passed to allpole need to implement a stable
      filter, since this is an IIR filter and stability is not
      guaranteed by default.
    </para>

        <para>
      The most common method of coefficient derivation is linear
      prediction analysis, produced for instance  by lpcanal. Other
      methods may be employed, including direct calculation of
      coefficients from a known filter recipe (e.g. resonators etc).
    </para>
   
      
  </refsect1>

  <refsect1>
    <title>Examples</title>
    <para>
      Here is an example of the allpole opcode using an audio input
      signal as lpc source. It uses the file <ulink url="examples/allpole.csd"><citetitle>allpole.csd</citetitle></ulink>.
      <example>
        <title>Example of the allpole 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/allpole.csd.xml" xmlns:xi="http://www.w3.org/2001/XInclude"/>
      </example>
    </para>
       <para>
      Here is another example of the allpole opcode, now using a
      function table as lpc source. It uses the file <ulink url="examples/allpole-2.csd"><citetitle>allpole-2.csd</citetitle></ulink>.
      <example>
        <title>Another example of the allpole 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/allpole-2.csd.xml" xmlns:xi="http://www.w3.org/2001/XInclude"/>
      </example>
    </para>
  </refsect1>
   
     <refsect1>
        <title>See also</title>
        <para><link linkend="SpectralLpcresyn"><citetitle>Streaming Linear Predictive Coding (SLPC) Resynthesis</citetitle></link></para>
    </refsect1>

</refentry>