165 lines
5.5 KiB
HTML
165 lines
5.5 KiB
HTML
<!DOCTYPE html>
|
|
|
|
<!--Converted with LaTeX2HTML 2002-2-1 (1.71)
|
|
original version by: Nikos Drakos, CBLU, University of Leeds
|
|
* revised and updated by: Marcus Hennecke, Ross Moore, Herb Swan
|
|
* with significant contributions from:
|
|
Jens Lippmann, Marek Rouchal, Martin Wilck and others -->
|
|
<HTML>
|
|
<HEAD>
|
|
|
|
<meta name="viewport" content="width=device-width, initial-scale=1.0">
|
|
|
|
|
|
<TITLE>Continuous and discontinuous control changes</TITLE>
|
|
<META NAME="description" CONTENT="Continuous and discontinuous control changes">
|
|
<META NAME="keywords" CONTENT="book">
|
|
<META NAME="resource-type" CONTENT="document">
|
|
<META NAME="distribution" CONTENT="global">
|
|
|
|
<META NAME="Generator" CONTENT="LaTeX2HTML v2002-2-1">
|
|
<META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css">
|
|
|
|
<LINK REL="STYLESHEET" HREF="book.css">
|
|
|
|
<LINK REL="next" HREF="node64.html">
|
|
<LINK REL="previous" HREF="node60.html">
|
|
<LINK REL="up" HREF="node58.html">
|
|
<LINK REL="next" HREF="node62.html">
|
|
</HEAD>
|
|
|
|
<BODY >
|
|
<!--Navigation Panel-->
|
|
<A ID="tex2html1459"
|
|
HREF="node62.html">
|
|
<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next"
|
|
SRC="next.png"></A>
|
|
<A ID="tex2html1453"
|
|
HREF="node58.html">
|
|
<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up"
|
|
SRC="up.png"></A>
|
|
<A ID="tex2html1447"
|
|
HREF="node60.html">
|
|
<IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous"
|
|
SRC="prev.png"></A>
|
|
<A ID="tex2html1455"
|
|
HREF="node4.html">
|
|
<IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents"
|
|
SRC="contents.png"></A>
|
|
<A ID="tex2html1457"
|
|
HREF="node201.html">
|
|
<IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index"
|
|
SRC="index.png"></A>
|
|
<BR>
|
|
<B> Next:</B> <A ID="tex2html1460"
|
|
HREF="node62.html">Muting</A>
|
|
<B> Up:</B> <A ID="tex2html1454"
|
|
HREF="node58.html">Automation and voice management</A>
|
|
<B> Previous:</B> <A ID="tex2html1448"
|
|
HREF="node60.html">Linear and Curved Amplitude</A>
|
|
<B> <A ID="tex2html1456"
|
|
HREF="node4.html">Contents</A></B>
|
|
<B> <A ID="tex2html1458"
|
|
HREF="node201.html">Index</A></B>
|
|
<BR>
|
|
<BR>
|
|
<!--End of Navigation Panel-->
|
|
|
|
<H1><A ID="SECTION00830000000000000000"></A>
|
|
<A ID="sect4.declick"></A>
|
|
<BR>
|
|
Continuous and discontinuous control changes
|
|
</H1>
|
|
|
|
<P>
|
|
Synthesis algorithms vary widely in their ability to deal with discontinuously
|
|
changing controls. Until now in this chapter we have assumed that controls
|
|
must change continuously, and the ADSR envelope generator turns out
|
|
to be ideally suited for such controls. It may even happen that
|
|
the maximum amplitude of a note is less than the current value of the amplitude
|
|
of its predecessor (using the same generator) and the ADSR envelope will simply
|
|
ramp down (instead of up) to the new value for an attack.
|
|
|
|
<P>
|
|
This isn't necessarily desirable, however, in situations where an envelope
|
|
generator is in charge of some aspect of timbre: perhaps, for example, we don't
|
|
want the sharpness of a note to decrease during the attack to a milder one, but
|
|
rather to jump to a much lower value so as always to be able to rise during the
|
|
attack.
|
|
|
|
<P>
|
|
This situation also can arise with pitch envelopes: it may be desirable to
|
|
slide pitch from one note to the next, or it may be desirable that the pitch
|
|
trajectory of each note start anew at a point independent of the previous
|
|
sound.
|
|
|
|
<P>
|
|
Two situations arise when we wish to make discontinuous changes to synthesis
|
|
parameters: either we can simply make them without disruption (for instance,
|
|
making a discontinuous change in pitch); or else we can't, such as a change in
|
|
a wavetable index (which makes a discontinuous change in the output). There
|
|
are even parameters that can't <I>possibly</I> be changed continuously; for
|
|
example, a selection among a collection of wavetables. In general,
|
|
discontinuously changing the phase of an oscillator or the amplitude of a
|
|
signal will cause an audible artifact, but phase increments (such as pitches)
|
|
may jump without bad results.
|
|
|
|
<P>
|
|
In those cases where a parameter change can't be made continuously for one
|
|
reason or another, there are at least two strategies for making the change
|
|
cleanly:
|
|
<I>muting</I> and <I>switch-and-ramp</I>.
|
|
|
|
<P>
|
|
<BR><HR>
|
|
<!--Table of Child-Links-->
|
|
<A ID="CHILD_LINKS"><STRONG>Subsections</STRONG></A>
|
|
|
|
<UL>
|
|
<LI><A ID="tex2html1461"
|
|
HREF="node62.html">Muting</A>
|
|
<LI><A ID="tex2html1462"
|
|
HREF="node63.html">Switch-and-ramp</A>
|
|
</UL>
|
|
<!--End of Table of Child-Links-->
|
|
<HR>
|
|
<!--Navigation Panel-->
|
|
<A ID="tex2html1459"
|
|
HREF="node62.html">
|
|
<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next"
|
|
SRC="next.png"></A>
|
|
<A ID="tex2html1453"
|
|
HREF="node58.html">
|
|
<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up"
|
|
SRC="up.png"></A>
|
|
<A ID="tex2html1447"
|
|
HREF="node60.html">
|
|
<IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous"
|
|
SRC="prev.png"></A>
|
|
<A ID="tex2html1455"
|
|
HREF="node4.html">
|
|
<IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents"
|
|
SRC="contents.png"></A>
|
|
<A ID="tex2html1457"
|
|
HREF="node201.html">
|
|
<IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index"
|
|
SRC="index.png"></A>
|
|
<BR>
|
|
<B> Next:</B> <A ID="tex2html1460"
|
|
HREF="node62.html">Muting</A>
|
|
<B> Up:</B> <A ID="tex2html1454"
|
|
HREF="node58.html">Automation and voice management</A>
|
|
<B> Previous:</B> <A ID="tex2html1448"
|
|
HREF="node60.html">Linear and Curved Amplitude</A>
|
|
<B> <A ID="tex2html1456"
|
|
HREF="node4.html">Contents</A></B>
|
|
<B> <A ID="tex2html1458"
|
|
HREF="node201.html">Index</A></B>
|
|
<!--End of Navigation Panel-->
|
|
<ADDRESS>
|
|
Miller Puckette
|
|
2006-12-30
|
|
</ADDRESS>
|
|
</BODY>
|
|
</HTML>
|