/usr/share/SuperCollider/HelpSource/Classes/Convolution2L.schelp is in supercollider-common 1:3.8.0~repack-2.
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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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 | class:: Convolution2L
summary:: Real-time convolver with linear interpolation
related:: Classes/Convolution, Classes/Convolution2, Classes/Convolution3, Classes/StereoConvolution2L
categories:: UGens>FFT, UGens>Convolution
Description::
Strict convolution with fixed kernel which can be updated using a trigger signal. There is a linear crossfade between the buffers upon change.
See emphasis:: Steven W Smith, The Scientist and Engineer's Guide to Digital Signal Processing: chapter 18:: -
http://www.dspguide.com/ch18.htm
classmethods::
private:: categories
method::ar
argument::in
processing target
argument::kernel
buffer index for the fixed kernel, may be modulated in combination with the trigger
argument::trigger
update the kernel on a change from <=0 to >0
argument::framesize
size of FFT frame, must be a power of two (512, 1024, 2048, 4096 are standard choices).
Convolution uses twice this number internally.
Note that the convolution gets progressively more expensive to run for higher powers!
The maximum value you can use is 2^16=16384.
(This upper limit is half of "SC_FFT_MAXSIZE" defined in the SC source code.)
Larger convolutions than this can be done using link::Classes/PartConv::.
argument::crossfade
The number of periods over which a crossfade is made. The default is 1. This must be an integer.
argument::mul
argument::add
Examples::
code::
(// allocate three buffers
b = Buffer.alloc(s, 2048);
c = Buffer.alloc(s, 2048);
d = Buffer.alloc(s, 2048);
b.zero;
c.zero;
d.zero;
)
(
50.do({ |it| c.set(20*it+10, 1.0.rand); });
3.do({ |it| b.set(400*it+100, 1); });
20.do({ |it| d.set(40*it+20, 1); });
)
::
code::
(
SynthDef(\conv_test, { arg kernel, t_trig=0;
var input;
input=Impulse.ar(1);
// must have power of two framesize
Out.ar(0, Convolution2L.ar(input, kernel, t_trig, 2048, 1, 0.5));
}).add
)
x = Synth(\conv_test, [\kernel, b]);
// changing the buffer number:
x.set(\kernel, c);
x.set(\t_trig, 1); // after this trigger, the change will take effect.
x.set(\kernel, d);
x.set(\t_trig, 1); // after this trigger, the change will take effect.
d.zero;
40.do({ |it| d.set(20*it+10, 1); });// changing the buffers' contents
x.set(\t_trig, 1); // after this trigger, the change will take effect.
x.set(\kernel, b);
x.set(\t_trig, 1); // after this trigger, the change will take effect.
x.free;
::
code::
// longer crossfade
(
SynthDef( \conv_test2, { arg kernel, t_trig=0;
var input;
input=Impulse.ar(1);
// must have power of two framesize
Out.ar(0, Convolution2L.ar(input, kernel, t_trig, 2048, 5, 0.5));
}).add
)
x = Synth(\conv_test2, [\kernel, b]);
// changing the buffer number:
x.set(\kernel, c);
x.set(\t_trig, 1); // after this trigger, the change will take effect.
x.set(\kernel, d);
x.set(\t_trig, 1); // after this trigger, the change will take effect.
d.zero;
40.do({ |it| d.set(20*it+10, 1); });// changing the buffers' contents
x.set(\t_trig, 1); // after this trigger, the change will take effect.
x.set(\kernel, b);
x.set(\t_trig, 1); // after this trigger, the change will take effect.
x.free;
::
code::
// next example
b = Buffer.read(s, Platform.resourceDir +/+ "sounds/a11wlk01.wav");
(
{ var input, kernel;
input= SoundIn.ar(0);
// must have power of two framesize
Convolution2L.ar(input, b, 0, 512, 1, 0.5);
}.play;
)
::
code::
// another example
(
// must have power of two framesize- FFT size will be sorted by Convolution2 to be double this
// maximum is currently a=8192 for FFT of size 16384
a=2048;
// kernel buffer
g = Buffer.alloc(s, a, 1);
)
(
g.set(0, 1.0);
100.do({arg i; g.set(a.rand, (i+1).reciprocal)});
)
(
// random impulse response
{
var input, inputAmp, threshhold, gate;
input = SoundIn.ar(0);
inputAmp = Amplitude.kr(input);
threshhold = 0.02; // noise gating threshold
gate = Lag.kr(inputAmp > threshhold, 0.01);
Convolution2L.ar(input*gate, g, 0, a, 1, 0.5);
}.play;
)
::
code::
// one last example
(
b = Buffer.alloc(s, 512, 1);
b.sine1(1.0/[1, 2, 3, 4, 5, 6], true, true, true);
)
(
{ var input, kernel;
input=SoundIn.ar(0);
// must have power of two framesize
Convolution2L.ar(input, b, 0, 512, 1, 0.5);
}.play;
)
::
|