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<section id="manipulating-audio-signal-in-input">
<h1>Manipulating audio signal in input<a class="headerlink" href="#manipulating-audio-signal-in-input" title="Permalink to this heading">¶</a></h1>
<p><strong>02-audio-in.py</strong></p>
<p>The expression illustrated in this example use a phasor signal
in input as the running phase of a self-modulated sine wave.</p>
<p>Here is the complete expression:</p>
<div class="highlight-scheme notranslate"><div class="highlight"><pre><span></span><span class="p">(</span><span class="nb">sin</span><span class="w"> </span><span class="p">(</span><span class="nb">+</span><span class="w"> </span><span class="p">(</span><span class="nb">*</span><span class="w"> </span><span class="nv">twopi</span><span class="w"> </span><span class="nv">$x</span><span class="p">[</span><span class="mi">0</span><span class="p">])</span><span class="w"> </span><span class="p">(</span><span class="nb">*</span><span class="w"> </span><span class="nv">$y</span><span class="p">[</span><span class="mi">-1</span><span class="p">]</span><span class="w"> </span><span class="mf">0.8</span><span class="p">)))</span><span class="w"></span>
</pre></div>
</div>
<p>From inner to outer expression, we have:</p>
<div class="highlight-scheme notranslate"><div class="highlight"><pre><span></span><span class="p">(</span><span class="nb">*</span><span class="w"> </span><span class="nv">$y</span><span class="p">[</span><span class="mi">-1</span><span class="p">]</span><span class="w"> </span><span class="mf">0.8</span><span class="p">)</span><span class="w"></span>
</pre></div>
</div>
<p>Where <cite>$y[-1]</cite> is the last output sample multiplied by a feedback
factor (0.8). Then we have the running phase, <cite>$x[0]</cite> is the current
input sample, rescaled to the range 0 -> 2pi for the <cite>sin</cite> function:</p>
<div class="highlight-scheme notranslate"><div class="highlight"><pre><span></span><span class="p">(</span><span class="nb">*</span><span class="w"> </span><span class="nv">twopi</span><span class="w"> </span><span class="nv">$x</span><span class="p">[</span><span class="mi">0</span><span class="p">])</span><span class="w"></span>
</pre></div>
</div>
<p>We add the output delay to the running phase:</p>
<div class="highlight-scheme notranslate"><div class="highlight"><pre><span></span><span class="p">(</span><span class="nb">+</span><span class="w"> </span><span class="p">(</span><span class="nb">*</span><span class="w"> </span><span class="nv">twopi</span><span class="w"> </span><span class="nv">$x</span><span class="p">[</span><span class="mi">0</span><span class="p">])</span><span class="w"> </span><span class="p">(</span><span class="nb">*</span><span class="w"> </span><span class="nv">$y</span><span class="p">[</span><span class="mi">-1</span><span class="p">]</span><span class="w"> </span><span class="mf">0.8</span><span class="p">))</span><span class="w"></span>
</pre></div>
</div>
<p>This gives the modulated running phase driving the <cite>sin</cite> function:</p>
<div class="highlight-scheme notranslate"><div class="highlight"><pre><span></span><span class="p">(</span><span class="nb">sin</span><span class="w"> </span><span class="p">(</span><span class="nb">+</span><span class="w"> </span><span class="p">(</span><span class="nb">*</span><span class="w"> </span><span class="nv">twopi</span><span class="w"> </span><span class="nv">$x</span><span class="p">[</span><span class="mi">0</span><span class="p">])</span><span class="w"> </span><span class="p">(</span><span class="nb">*</span><span class="w"> </span><span class="nv">$y</span><span class="p">[</span><span class="mi">-1</span><span class="p">]</span><span class="w"> </span><span class="mf">0.8</span><span class="p">)))</span><span class="w"></span>
</pre></div>
</div>
<section id="complete-example">
<h2>Complete example<a class="headerlink" href="#complete-example" title="Permalink to this heading">¶</a></h2>
<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">"""</span>
<span class="s2">// Self-modulated sine wave with running phase given in input.</span>
<span class="s2">// Try different feedback factors between 0 and 1.</span>
<span class="s2">(sin (+ (* twopi $x[0]) (* $y[-1] 0.8)))</span>
<span class="s2">"""</span>
<span class="c1"># External signal used as the running phase.</span>
<a class="sphinx-codeautolink-a" href="../../api/classes/generators.html#pyo.Phasor" title="pyo.lib.generators.Phasor"><span class="nb">input</span></a> <span class="o">=</span> <a class="sphinx-codeautolink-a" href="../../api/classes/generators.html#pyo.Phasor" title="pyo.lib.generators.Phasor"><span class="n">Phasor</span></a><span class="p">(</span><span class="mi">86</span><span class="p">)</span>
<span class="nb">input</span><span class="o">.</span><span class="n">ctrl</span><span class="p">()</span>
<span class="c1"># Create the Expr object and show its expression editor. To</span>
<span class="c1"># re-evaluate the expression hit Ctrl+Enter when the editor</span>
<span class="c1"># has the focus.</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/generators.html#pyo.Phasor" title="pyo.lib.generators.Phasor"><span class="nb">input</span></a><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>
<span class="c1"># Shows the generated signal.</span>
<a class="sphinx-codeautolink-a" href="../../api/classes/analysis.html#pyo.Scope" title="pyo.lib.analysis.Scope"><span class="n">sc</span></a> <span class="o">=</span> <a class="sphinx-codeautolink-a" href="../../api/classes/analysis.html#pyo.Scope" title="pyo.lib.analysis.Scope"><span class="n">Scope</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="c1"># Converts the mono signal to stereo and sends it to the soundcard.</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>
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