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<body><b><font size="5"><font color="#000000">FFTDiffMags A simple spectral difference measure<!--invalid font number 1-->
</font></font></b><font size="5"><font color="#000000"><span style="font-size:9pt"><br>
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<font size="3">Compares the spectra of two signals, finding the magnitude of the difference for each frequency bin. These differences are averaged onto the (control-rate) output.<br>
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<b><font size="3"><font color="#000000"> FFTDiffMags.kr(chain1, chain2)<br>
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<span style="font-size:9pt"><font color="#bf0000"> <br>
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<font size="3"><font color="#000000">Note that this crude measure works on a bin-by-bin basis and is not clever enough to detect higher-order similarities between spectra (such as general treble/bass balance).<br>
<br>
See also PV_DiffMags which performs the same calculation but doesn't sum the difference values - it leaves them in the frequency-domain buffer for further use.<br>
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<font color="#bf0000">// How different are the spectra of square waves at different PWM settings?<font color="#000000"><br>
<font color="#bf0000">// This test outputs two square waves, one of whose PWM is controlled by <font color="#000000"><br>
<font color="#bf0000">// MouseX - in the middle of the screen, the PWMs match,<font color="#000000"><br>
<font color="#bf0000">// but at either side they are more different.<font color="#000000"><br>
<font color="#bf0000">// Watch the output to channel 0 to see the shape of the returned signal<font color="#000000"><br>
<br>
<font color="#0000bf">Server<font color="#000000">.default_(s = <font color="#0000bf">Server<font color="#000000">.internal.boot);<br>
b = <font color="#0000bf">Buffer<font color="#000000">.alloc(s, 1024, 1);<br>
c = <font color="#0000bf">Buffer<font color="#000000">.alloc(s, 1024, 1);<br>
(<br>
{<br>
<font color="#0000bf">var<font color="#000000"> chain1, chain2, chain, sig1, sig2, difference;<br>
sig1 = <font color="#0000bf">Pulse<font color="#000000">.ar(100, <font color="#0000bf">MouseX<font color="#000000">.kr(0.1, 0.9));<br>
sig2 = <font color="#0000bf">Pulse<font color="#000000">.ar(100, 0.5);<br>
chain1 = <font color="#0000bf">FFT<font color="#000000">(b.bufnum, sig1);<br>
chain2 = <font color="#0000bf">FFT<font color="#000000">(c.bufnum, sig2);<br>
difference = <font color="#0000bf">FFTDiffMags<font color="#000000">.kr(chain1, chain2);<br>
<br>
difference.poll(1, <font color="#606060">"difference between spectra:"<font color="#000000">);<br>
<font color="#000000"><br>
[sig1, sig2] * 0.1;<br>
}.scope<br>
)</font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></font></span></body>
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