146 lines
4.7 KiB
HTML
146 lines
4.7 KiB
HTML
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original version by: Nikos Drakos, CBLU, University of Leeds
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* revised and updated by: Marcus Hennecke, Ross Moore, Herb Swan
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* with significant contributions from:
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<H2><A ID="SECTION007105000000000000000">
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Analog-style sequencer</A>
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</H2>
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<P>
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Example C08.analog.sequencer.pd (Figure <A HREF="#fig03.15">3.15</A>) realizes the analog sequencer and envelope
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generation described in Section <A HREF="node47.html#sect3.analog">3.7</A>. The "sequence" table,
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with nine elements, holds a sequence of frequencies. The <TT>phasor~</TT> object at top cycles through the sequence table at 0.6 Hertz. Non-interpolating
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table lookup (<TT>tabread~</TT> instead of <TT>tabread4~</TT>) is
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used to read the frequencies in discrete steps. (Such situations, in
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which we prefer non-interpolating table lookup, are rare.)
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<P>
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<DIV ALIGN="CENTER"><A ID="fig03.15"></A><A ID="3777"></A>
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<TABLE>
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<CAPTION ALIGN="BOTTOM"><STRONG>Figure 3.15:</STRONG>
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An analog-synthesizer-style sequencer.</CAPTION>
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<TR><TD><IMG
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WIDTH="463" HEIGHT="692" BORDER="0"
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ALT="\begin{figure}\psfig{file=figs/fig03.15.ps}\end{figure}"></TD></TR>
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</TABLE>
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</DIV>
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<P>
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The <TT>wrap~</TT> object converts the amplitude-9 sawtooth to a unit-amplitude
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one as described earlier in Figure <A HREF="node47.html#fig03.08">3.8</A>, which is then used to obtain
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an envelope function from a second wavetable. This is used to control grain
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size in a looping sampler (from Section <A HREF="node36.html#sect2.example.loop">2.6</A>). Here the
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wavetable consists of six periods of a sinusoid. The grains are smoothed by
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multiplying by a raised cosine function (<TT>cos~</TT> and <TT>+ 1</TT>).
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<P>
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Example C09.sample.hold.pd (not pictured here) shows a sample-and-hold unit, another
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useful device for doing control tasks in the audio signal domain.
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<B> Next:</B> <A ID="tex2html1364"
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HREF="node56.html">MIDI-style synthesizer</A>
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HREF="node50.html">Examples</A>
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HREF="node54.html">Signals to controls</A>
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<ADDRESS>
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Miller Puckette
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2006-12-30
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