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<p class="p1"><b>FFTSpread<span class="Apple-tab-span"> </span><span class="Apple-tab-span"> </span>Spectral spread</b></p>
<p class="p2"><br></p>
<p class="p3"><b><span class="Apple-tab-span"> </span>FFTSpread.kr(chain, centroid)</b></p>
<p class="p2"><br></p>
<p class="p3">Given an <a href="SC://FFT"><span class="s1">FFT</span></a> <b>chain</b>, this measures the <i>spectral spread</i>, which is the magnitude-weighted variance. This measure can serve as an (approximate) clue towards the bandwidth of a signal (although the value is not a frequency).</p>
<p class="p2"><br></p>
<p class="p3">The <b>centroid</b> should be supplied, typically using a <a href="SC://SpecCentroid"><span class="s1">SpecCentroid</span></a> unit - if you don't fill in this argument then a SpecCentroid unit will automatically be added.</p>
<p class="p2"><br></p>
<p class="p2"><br></p>
<p class="p3"><b>Example</b></p>
<p class="p2"><br></p>
<p class="p4">// Very artificial example - just filtering some noise.</p>
<p class="p5">s.boot;</p>
<p class="p5">b = <span class="s2">Buffer</span>.alloc(s,2048,1);</p>
<p class="p5">(</p>
<p class="p5">x = {</p>
<p class="p5"><span class="s2">var</span> in, chain, freq, rq, val;</p>
<p class="p6"><br></p>
<p class="p4">//freq = LFPar.kr(0.3).exprange(100, 1000);</p>
<p class="p5">freq = <span class="s2">MouseY</span>.kr(1000, 100, 1);</p>
<p class="p5">rq = <span class="s2">MouseX</span>.kr(0.001, 10, 1);</p>
<p class="p6"><br></p>
<p class="p5">in = <span class="s2">BPF</span>.ar(<span class="s2">WhiteNoise</span>.ar, freq, rq);</p>
<p class="p6"><br></p>
<p class="p5">chain = <span class="s2">FFT</span>(b.bufnum, in);</p>
<p class="p6"><br></p>
<p class="p5">val = <span class="s2">FFTSpread</span>.kr(chain);</p>
<p class="p6"><br></p>
<p class="p5"><span class="s2">Out</span>.ar(0, in.dup * 0.1);</p>
<p class="p5">(val * 0.000001).poll(10); // Poll but scaled down so more readable!</p>
<p class="p5">}.play(s);</p>
<p class="p5">)</p>
<p class="p6"><br></p>
<p class="p5">x.free;</p>
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