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{\fonttbl\f0\fswiss\fcharset77 Helvetica-Bold;\f1\fnil\fcharset77 Monaco;\f2\fswiss\fcharset77 Helvetica;
}
{\colortbl;\red255\green255\blue255;\red191\green0\blue0;\red0\green0\blue191;\red96\green96\blue96;
}
\pard\tx560\tx1120\tx1680\tx2240\tx2800\tx3360\tx3920\tx4480\tx5040\tx5600\tx6160\tx6720\ql\qnatural\pardirnatural
\f0\b\fs36 \cf0 FFTSubbandPower - Spectral power, divided into subbands
\f1\b0\fs34 \
\pard\tx560\tx1120\tx1680\tx2240\tx2800\tx3360\tx3920\tx4480\tx5040\tx5600\tx6160\tx6720\ql\qnatural\pardirnatural
\fs22 \cf0 \
\pard\tx560\tx1120\tx1680\tx2240\tx2800\tx3360\tx3920\tx4480\tx5040\tx5600\tx6160\tx6720\ql\qnatural\pardirnatural
\f0\b\fs24 \cf0 #[power1, power2, ... powerN+1] = FFTSubbandPower.kr(chain, [cutfreq1, cutfreq2, ... cutfreqN], incdc)\
\f2\b0 \
Calculates the spectral power measure, in the same manner as [\ul FFTPower\ulnone ], but divides the spectrum into (adjacent, non-overlapping) subbands, so returns separate power measures for the different subbands.\
\
The
\f0\b cutfreqs
\f2\b0 parameter must be an array of frequencies. For example, to divide a 44100Hz signal into three subbands we might specify [ 5512, 11025 ] as the cutfreqs, giving subbands of 0-5512Hz, 5512-11025Hz, and 11025-22050Hz. (Frequencies above the Nyquist frequency are not included.)\
\
The third parameter
\f0\b incdc
\f2\b0 specifies whether the DC power should be included in the measurement. It defaults to 1; set it as zero to exclude the DC component.\
\
\f0\b cutfreqs
\f2\b0 and
\f0\b incdc
\f2\b0 can only be specified on initialisation - they can't be modulated.\
\
\
\f0\b Examples
\f2\b0 \
\pard\tx560\tx1120\tx1680\tx2240\tx2800\tx3360\tx3920\tx4480\tx5040\tx5600\tx6160\tx6720\ql\qnatural
\f1\fs18 \cf0 \
\cf2 // Simple example\cf0 \
s = \cf3 Server\cf0 .local.boot; \cf2 //Server.internal.boot;\cf0 \
b = \cf3 Buffer\cf0 .alloc(s,2048,1);\
(\
x = \{\
\cf3 var\cf0 in, chain, powers, cutfreqs;\
in = \cf3 LPF\cf0 .ar(\cf3 WhiteNoise\cf0 .ar, \cf3 MouseX\cf0 .kr(10,10000, 1));\
chain = \cf3 FFT\cf0 (b.bufnum, in);\
\
powers = \cf3 FFTSubbandPower\cf0 .kr(chain, [100, 200, 400, 800, 1600, 3200, 6400, 12800]);\
\cf3 \
Out\cf0 .ar(0, in * 0.1);\
powers.poll(0.4);\
\}.play(s);\
)\
\
x.free;\
\
\f2\fs24 \
In this next example we create a
\f0\b graphic EQ meter
\f2\b0 . The subband power measurements are written out to a control bus, then on the language side we create a task which polls the values and updates a multi-slider to display the power distribution in the familiar home hi-fi style.
\f1\fs18 \
\
s = \cf3 Server\cf0 .local.boot;\
b = \cf3 Buffer\cf0 .alloc(s,2048,1);\
(\
\cf3 var\cf0 win, size=8;\
c = \cf3 Bus\cf0 .control(s, size); \cf2 // Values will be written to control busses\cf0 \
win = \cf3 SCWindow\cf0 (\cf4 "EQ meter"\cf0 , \cf3 Rect\cf0 (100, 200, 360, 110));\
~slider = \cf3 SCMultiSliderView\cf0 (win, \cf3 Rect\cf0 (0, 0, 350, 100));\
~slider.value_(0.dup(size)).size_(size).isFilled_(\cf3 true\cf0 ).indexThumbSize_(350/8);\
win.front;\
)\
(\
\cf3 var\cf0 size=8;\
x = \{\
\cf3 var\cf0 in, chain, powers, cutfreqs;\
in = \cf3 LPF\cf0 .ar(\cf3 WhiteNoise\cf0 .ar, \cf3 MouseX\cf0 .kr(10,10000, 1));\
chain = \cf3 FFT\cf0 (b.bufnum, in);\
cutfreqs = [100, 200, 400, 800, 1600, 3200, 6400];\
powers = \cf3 FFTSubbandPower\cf0 .kr(chain, cutfreqs, 0);\
\cf3 Out\cf0 .ar(0, (in * 0.1).dup);\
\cf3 Out\cf0 .kr(c.index, powers);\
\}.play(s);\
\
t = \cf3 Task\cf0 (\{\
loop\{\
0.1.wait;\
c.getn(size, \{\cf3 |vals|\cf0 \{\
~slider.value_((vals.log2 * 0.2).max(0));\
\}.defer\});\
\};\
\}).start;\
)\
\
x.free;\
t.stop;\
}
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