1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
|
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8"/>
<meta content="width=device-width, initial-scale=1.0" name="viewport"/><meta content="Docutils 0.17.1: http://docutils.sourceforge.net/" name="generator"/>
<title>State variable inside an expression — Pyo 1.0.5 documentation</title>
<link href="../../_static/pygments.css" rel="stylesheet" type="text/css"/>
<link href="../../_static/agogo.css" rel="stylesheet" type="text/css"/>
<link href="../../_static/sphinx-codeautolink.css" rel="stylesheet" type="text/css"/>
<link href="../../_static/autoclasstoc.css" rel="stylesheet" type="text/css"/>
<script data-url_root="../../" id="documentation_options" src="../../_static/documentation_options.js"></script>
<script src="../../_static/jquery.js"></script>
<script src="../../_static/underscore.js"></script>
<script src="../../_static/_sphinx_javascript_frameworks_compat.js"></script>
<script src="../../_static/doctools.js"></script>
<script src="../../_static/sphinx_highlight.js"></script>
<link href="../../_static/E-PyoIcon.ico" rel="shortcut icon"/>
<link href="../../about.html" rel="author" title="About these documents"/>
<link href="../../genindex.html" rel="index" title="Index"/>
<link href="../../search.html" rel="search" title="Search"/>
<link href="05-define-function.html" rel="next" title="Creating our own functions"/>
<link href="03-multiple-inputs.html" rel="prev" title="Using more than one input signal in a single expression"/>
</head><body>
<div class="header-wrapper" role="banner">
<div class="header">
<div class="headertitle"><a href="../../index.html">Pyo 1.0.5 documentation</a></div>
<div aria-label="related navigation" class="rel" role="navigation">
<a accesskey="P" href="03-multiple-inputs.html" title="Using more than one input signal in a single expression">previous</a> |
<a accesskey="N" href="05-define-function.html" title="Creating our own functions">next</a> |
<a accesskey="I" href="../../genindex.html" title="General Index">index</a>
</div>
</div>
</div>
<div class="content-wrapper">
<div class="content">
<div class="sidebar">
<h3>Table of Contents</h3>
<ul>
<li class="toctree-l1"><a class="reference internal" href="../../about.html">About pyo</a></li>
<li class="toctree-l1"><a class="reference internal" href="../../download.html">Installing pyo with pip</a></li>
<li class="toctree-l1"><a class="reference internal" href="../../compiling.html">Compiling pyo from sources</a></li>
<li class="toctree-l1"><a class="reference internal" href="../../structure.html">Structure of the library</a></li>
<li class="toctree-l1"><a class="reference internal" href="../../gettingstarted.html">Getting started</a></li>
<li class="toctree-l1"><a class="reference internal" href="../../winaudioinspect.html">Configuring the audio output (Windows)</a></li>
<li class="toctree-l1"><a class="reference internal" href="../../perftips.html">Improve performance of pyo programs</a></li>
</ul>
<ul class="current">
<li class="toctree-l1"><a class="reference internal" href="../../api/index.html">API documentation</a></li>
<li class="toctree-l1 current"><a class="reference internal" href="../index.html">Examples</a><ul class="current">
<li class="toctree-l2"><a class="reference internal" href="../01-intro/index.html">First steps</a></li>
<li class="toctree-l2"><a class="reference internal" href="../02-controls/index.html">Parameter control</a></li>
<li class="toctree-l2"><a class="reference internal" href="../03-generators/index.html">Synthesis generators</a></li>
<li class="toctree-l2"><a class="reference internal" href="../04-soundfiles/index.html">Playing with soundfiles</a></li>
<li class="toctree-l2"><a class="reference internal" href="../05-envelopes/index.html">Amplitude envelopes</a></li>
<li class="toctree-l2"><a class="reference internal" href="../06-filters/index.html">Filtering</a></li>
<li class="toctree-l2"><a class="reference internal" href="../07-effects/index.html">Creating sound effects</a></li>
<li class="toctree-l2"><a class="reference internal" href="../08-dynamics/index.html">Dynamic range of audio signals</a></li>
<li class="toctree-l2"><a class="reference internal" href="../09-callbacks/index.html">Calling python functions from audio objects</a></li>
<li class="toctree-l2"><a class="reference internal" href="../10-tables/index.html">Using tables</a></li>
<li class="toctree-l2"><a class="reference internal" href="../16-midi/index.html">How to use MIDI with pyo</a></li>
<li class="toctree-l2"><a class="reference internal" href="../17-osc/index.html">How to use OSC with pyo</a></li>
<li class="toctree-l2"><a class="reference internal" href="../19-multirate/index.html">Multirate audio processing</a></li>
<li class="toctree-l2"><a class="reference internal" href="../20-multicore/index.html">Multicore audio programming</a></li>
<li class="toctree-l2"><a class="reference internal" href="../21-utilities/index.html">Utilities</a></li>
<li class="toctree-l2"><a class="reference internal" href="../22-events/index.html">Events framework</a></li>
<li class="toctree-l2 current"><a class="reference internal" href="index.html">Evaluating prefix expression</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="../../tutorials/index.html">Advanced tutorials</a></li>
</ul>
<div role="search">
<h3 style="margin-top: 1.5em;">Search</h3>
<form action="../../search.html" class="search" method="get">
<input name="q" type="text"/>
<input type="submit" value="Go"/>
</form>
</div>
</div>
<div class="document">
<div class="documentwrapper">
<div class="bodywrapper">
<div class="body" role="main">
<section id="state-variable-inside-an-expression">
<h1>State variable inside an expression<a class="headerlink" href="#state-variable-inside-an-expression" title="Permalink to this heading">¶</a></h1>
<p><strong>04-let-function.py</strong></p>
<p>User can create state variable with the keyword <cite>let</cite>. This is
useful to set an intermediate state to be used in multiple places
in the processing chain. The syntax is:</p>
<div class="highlight-scheme notranslate"><div class="highlight"><pre><span></span><span class="p">(</span><span class="k">let</span><span class="w"> </span><span class="o">#</span><span class="nv">var</span><span class="w"> </span><span class="p">(</span><span class="nf">body</span><span class="p">))</span><span class="w"></span>
</pre></div>
</div>
<p>The variable name must begin with a <cite>#</cite>.</p>
<p>The prefix expression <a class="reference external" href="http://ajaxsoundstudio.com/pyodoc/api/classes/expression.html">documentation</a> gives common use cases where we
may want to use state variables.</p>
<p>The following example implements a phase-aligned formant (PAF) generator, as
described by Miller Puckette in “The Theory and Technique of Electronic
Music”, p158.</p>
<div class="highlight-python notranslate"><div class="highlight"><pre><span></span><span class="kn">from</span> <a class="sphinx-codeautolink-a" href="../../api/alphabetical.html#module-pyo" title="pyo"><span class="nn">pyo</span></a> <span class="kn">import</span> <span class="o">*</span>
<span class="n">s</span> <span class="o">=</span> <a class="sphinx-codeautolink-a" href="../../api/classes/server.html#pyo.Server" title="pyo.lib.server.Server"><span class="n">Server</span></a><span class="p">()</span><span class="o">.</span><span class="n">boot</span><span class="p">()</span>
<span class="n">expression</span> <span class="o">=</span> <span class="s2">"""// PAF generator (single formant) //</span>
<span class="s2">// User variables</span>
<span class="s2">(let #fund 100) // fundamental frequency</span>
<span class="s2">(let #band 600) // formant bandwidth</span>
<span class="s2">(let #form 600) // formant center frequency</span>
<span class="s2">// Intermediate variables</span>
<span class="s2">(let #bw (/ #band #fund))</span>
<span class="s2">(let #cf (/ #form #fund))</span>
<span class="s2">(let #ph (* (- (~ #fund) 0.5) twopi))</span>
<span class="s2">(let #car ( // Carrier</span>
<span class="s2"> (cos (max (min (* #ph #bw) pi) (- 0 pi)))</span>
<span class="s2"> )</span>
<span class="s2">)</span>
<span class="s2">(let #mod ( // Modulator</span>
<span class="s2"> (let #oct (floor #cf))</span>
<span class="s2"> (let #frac (</span><span class="si">% #c</span><span class="s2">f 1))</span>
<span class="s2"> (+ (* (cos (* #ph #oct)) (- 1 #frac))</span>
<span class="s2"> (* (cos (* #ph (+ #oct 1))) #frac)</span>
<span class="s2"> )</span>
<span class="s2"> )</span>
<span class="s2">)</span>
<span class="s2">* (* #car #mod) 0.5</span>
<span class="s2">"""</span>
<a class="sphinx-codeautolink-a" href="../../api/classes/expression.html#pyo.Expr" title="pyo.lib.expression.Expr"><span class="n">expr</span></a> <span class="o">=</span> <a class="sphinx-codeautolink-a" href="../../api/classes/expression.html#pyo.Expr" title="pyo.lib.expression.Expr"><span class="n">Expr</span></a><span class="p">(</span><a class="sphinx-codeautolink-a" href="../../api/classes/controls.html#pyo.Sig" title="pyo.lib._core.Sig"><span class="n">Sig</span></a><span class="p">(</span><span class="mi">0</span><span class="p">),</span> <span class="n">expression</span><span class="p">,</span> <span class="n">mul</span><span class="o">=</span><span class="mf">0.5</span><span class="p">)</span>
<span class="n">expr</span><span class="o">.</span><span class="n">editor</span><span class="p">()</span>
<a class="sphinx-codeautolink-a" href="../../api/classes/analysis.html#pyo.Spectrum" title="pyo.lib.analysis.Spectrum"><span class="n">sp</span></a> <span class="o">=</span> <a class="sphinx-codeautolink-a" href="../../api/classes/analysis.html#pyo.Spectrum" title="pyo.lib.analysis.Spectrum"><span class="n">Spectrum</span></a><span class="p">(</span><a class="sphinx-codeautolink-a" href="../../api/classes/expression.html#pyo.Expr" title="pyo.lib.expression.Expr"><span class="n">expr</span></a><span class="p">)</span>
<span class="n">pan</span> <span class="o">=</span> <a class="sphinx-codeautolink-a" href="../../api/classes/pan.html#pyo.Pan" title="pyo.lib.pan.Pan"><span class="n">Pan</span></a><span class="p">(</span><a class="sphinx-codeautolink-a" href="../../api/classes/expression.html#pyo.Expr" title="pyo.lib.expression.Expr"><span class="n">expr</span></a><span class="p">)</span><span class="o">.</span><span class="n">out</span><span class="p">()</span>
<span class="n">s</span><span class="o">.</span><span class="n">gui</span><span class="p">(</span><span class="nb">locals</span><span class="p">())</span>
</pre></div>
</div>
</section>
<div class="clearer"></div>
</div>
</div>
</div>
</div>
<div class="clearer"></div>
</div>
</div>
<div class="footer-wrapper">
<div class="footer">
<div class="left">
<div aria-label="related navigaton" role="navigation">
<a href="03-multiple-inputs.html" title="Using more than one input signal in a single expression">previous</a> |
<a href="05-define-function.html" title="Creating our own functions">next</a> |
<a href="../../genindex.html" title="General Index">index</a>
</div>
<div aria-label="source link" role="note">
</div>
</div>
<div class="right">
<div class="footer" role="contentinfo">
© Copyright 2021, Olivier Bélanger.
Created using <a href="https://www.sphinx-doc.org/">Sphinx</a> 5.3.0.
</div>
</div>
<div class="clearer"></div>
</div>
</div>
</body>
</html>
|
