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<refentry id="deltapn">
<indexterm id="IndexDeltapn"><primary>deltapn</primary></indexterm>
<refentryinfo><title>Signal Modifiers:Delay</title></refentryinfo>
<refmeta>
<refentrytitle>deltapn</refentrytitle>
</refmeta>
<refnamediv>
<refname>deltapn</refname>
<refpurpose>
Taps a delay line at variable offset times.
</refpurpose>
</refnamediv>
<refsect1>
<title>Description</title>
<para>
Tap a delay line at variable offset times.
</para>
</refsect1>
<refsect1>
<title>Syntax</title>
<synopsis>ares <command>deltapn</command> xnumsamps</synopsis>
</refsect1>
<refsect1>
<title>Performance</title>
<para>
<emphasis>xnumsamps</emphasis> -- specifies the tapped delay time in number of samples. Each can range from 1 control period to the full delay time of the read/write pair; however, since there is no internal check for adherence to this range, the user is wholly responsible. Each argument can be a constant, a variable, or a time-varying signal.
</para>
<para>
<emphasis>deltapn</emphasis> is identical to <link linkend="deltapi"><citetitle>deltapi</citetitle></link>, except delay time is specified in number of samples, instead of seconds (&namehans;).
</para>
<para>
This opcode can tap into a <emphasis>delayr</emphasis>/<emphasis>delayw</emphasis> pair, extracting delayed audio from the <emphasis>idlt</emphasis> seconds of stored sound. There can be any number of <emphasis>deltap</emphasis> and/or <emphasis>deltapi</emphasis> units between a read/write pair. Each receives an audio tap with no change of original amplitude.
</para>
<para>
This opcode can provide multiple delay taps for arbitrary delay path and feedback networks. They can deliver either constant-time or time-varying taps, and are useful for building chorus effects, harmonizers, and Doppler shifts. Constant-time delay taps (and some slowly changing ones) do not need interpolated readout; they are well served by <emphasis>deltap</emphasis>. Medium-paced or fast varying dlt's, however, will need the extra services of <emphasis>deltapi</emphasis>.
</para>
<para>
<emphasis>delayr</emphasis>/<emphasis>delayw</emphasis> pairs may be interleaved. To associate a delay tap unit with a specific <emphasis>delayr</emphasis> unit, it not only has to be located between that <emphasis>delayr</emphasis> and the appropriate <emphasis>delayw</emphasis> unit, but must also precede any following <emphasis>delayr</emphasis> units. See Example 2. (This feature added in Csound version 3.57 by Jens Groh and &namejohn;).
</para>
<para>
<emphasis>N.B.</emphasis> k-rate delay times are not internally interpolated, but rather lay down stepped time-shifts of audio samples; this will be found quite adequate for slowly changing tap times. For medium to fast-paced changes, however, one should provide a higher resolution audio-rate timeshift as input.
</para>
</refsect1>
<refsect1>
<title>Examples</title>
<para>
<example>
<title>deltap example #1</title>
<programlisting>
asource <emphasis>buzz</emphasis> 1, 440, 20, 1
atime <emphasis>linseg</emphasis> 1, p3/2,.01, p3/2,1 ; trace a distance in secs
ampfac <emphasis>=</emphasis> 1/atime/atime ; and calc an amp factor
adump <emphasis>delayr</emphasis> 1 ; set maximum distance
amove <emphasis>deltapi</emphasis> atime ; move sound source past
<emphasis>delayw</emphasis> asource ; the listener
<emphasis>out</emphasis> amove * ampfac
</programlisting>
</example>
</para>
<para>
<example>
<title>deltap example #2</title>
<programlisting>
ainput1 = .....
ainput2 = .....
kdlyt1 = .....
kdlyt2 = .....
;Read delayed signal, first delayr instance:
adump <emphasis>delayr</emphasis> 4.0
adly1 <emphasis>deltap</emphasis> kdlyt1 ;associated with first delayr instance
;Read delayed signal, second delayr instance:
adump <emphasis>delayr</emphasis> 4.0
adly2 <emphasis>deltap</emphasis> kdlyt2 ; associated with second delayr instance
;Do some cross-coupled manipulation:
afdbk1 = 0.7 * adly1 + 0.7 * adly2 + ainput1
afdbk2 = -0.7 * adly1 + 0.7 * adly2 + ainput2
;Feed back signal, associated with first delayr instance:
<emphasis>delayw</emphasis> afdbk1
;Feed back signal, associated with second delayr instance:
<emphasis>delayw</emphasis> afdbk2
<emphasis>outs</emphasis> adly1, adly2
</programlisting>
</example>
</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<link linkend="deltap"><citetitle>deltap</citetitle></link>,
<link linkend="deltap3"><citetitle>deltap3</citetitle></link>,
<link linkend="deltapi"><citetitle>deltapi</citetitle></link>
</para>
</refsect1>
</refentry>
|
