Help/UGens/FFT/PartConv.html

   1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
   2 <html>
   3 <head>
   4 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
   5 <meta http-equiv="Content-Style-Type" content="text/css">
   6 <title></title>
   7 <meta name="Generator" content="Cocoa HTML Writer">
   8 <meta name="CocoaVersion" content="949.43">
   9 <style type="text/css">
  10 p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 18.0px Helvetica}
  11 p.p2 {margin: 0.0px 0.0px 0.0px 0.0px; font: 9.0px Monaco; min-height: 12.0px}
  12 p.p3 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica}
  13 p.p4 {margin: 0.0px 0.0px 0.0px 0.0px; font: 12.0px Helvetica; min-height: 14.0px}
  14 p.p5 {margin: 0.0px 0.0px 0.0px 0.0px; font: 9.0px Monaco; color: #ad140d}
  15 p.p6 {margin: 0.0px 0.0px 0.0px 0.0px; font: 9.0px Monaco}
  16 p.p7 {margin: 0.0px 0.0px 0.0px 0.0px; font: 9.0px Monaco; color: #ad140d; min-height: 12.0px}
  17 p.p8 {margin: 0.0px 0.0px 0.0px 0.0px; font: 9.0px Monaco; color: #606060}
  18 p.p9 {margin: 0.0px 0.0px 0.0px 0.0px; font: 9.0px Monaco; color: #90251e}
  19 p.p10 {margin: 0.0px 0.0px 0.0px 0.0px; font: 9.0px Monaco; color: #000000}
  20 span.s1 {color: #000000}
  21 span.s2 {color: #001bb9}
  22 span.s3 {color: #ad140d}
  23 span.Apple-tab-span {white-space:pre}
  24 </style>
  25 </head>
  26 <body>
  27 <p class="p1"><b>PartConv<span class="Apple-tab-span">  </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span>real-time partitioned convolution</b></p>
  28 <p class="p2"><br></p>
  29 <p class="p3"><b>PartConv.ar(in, fftsize, irbufnum, mul, add)</b></p>
  30 <p class="p2"><br></p>
  31 <p class="p3">Partitioned convolution. Various additional buffers must be supplied.<span class="Apple-converted-space"> </span></p>
  32 <p class="p4"><br></p>
  33 <p class="p3">Mono impulse response only! If inputting multiple channels, you'll need independent PartConvs, one for each channel.</p>
  34 <p class="p4"><br></p>
  35 <p class="p3">But the charm is: impulse response can be as large as you like (CPU load increases with IR size. Various tradeoffs based on fftsize choice, due to rarer but larger FFTs. This plug-in uses amortisation to spread processing and avoid spikes).</p>
  36 <p class="p4"><br></p>
  37 <p class="p3">Normalisation factors difficult to anticipate; convolution piles up multiple copies of the input on top of itself, so can easily overload.<span class="Apple-converted-space"> </span></p>
  38 <p class="p4"><br></p>
  39 <p class="p3"><b>in</b> - processing target</p>
  40 <p class="p3"><b>fftsize</b>- spectral convolution partition size (twice partition size). You must ensure that the blocksize divides the partition size and there are at least two blocks per partition (to allow for amortisation)</p>
  41 <p class="p3"><b>irbufnum</b>- Prepared buffer of spectra for each partition of the inpulse response</p>
  42 <p class="p2"><br></p>
  43 <p class="p2"><br></p>
  44 <p class="p2"><br></p>
  45 <p class="p2"><br></p>
  46 <p class="p2"><br></p>
  47 <p class="p5">// preparation; essentially, allocate an impulse response buffer, then follow a special buffer preparation step to set up the data the plugin needs. Different options are provided commented out for loading impulse responses from soundfiles.</p>
  48 <p class="p6">(</p>
  49 <p class="p5"><span class="s1">~fftsize=2048; </span>// also 4096 works on my machine; 1024 too often and amortisation too pushed, 8192 more high load FFT</p>
  50 <p class="p2"><br></p>
  51 <p class="p6">s.waitForBoot {</p>
  52 <p class="p2"><br></p>
  53 <p class="p6">{</p>
  54 <p class="p6"><span class="s2">var</span> ir, irbuffer, bufsize;<span class="Apple-converted-space"> </span></p>
  55 <p class="p2"><span class="Apple-tab-span">     </span></p>
  56 <p class="p5"><span class="s1"><span class="Apple-tab-span">    </span></span>// // MONO ONLY</p>
  57 <p class="p5"><span class="Apple-tab-span">     </span>// pre-existing impulse response sound files<span class="Apple-converted-space"> </span></p>
  58 <p class="p5"><span class="Apple-tab-span">     </span>// (could also use any general soundfile too for cross-synthesis effects)</p>
  59 <p class="p5"><span class="Apple-tab-span">     </span>// irbuffer= Buffer.read(s, "/Volumes/data/audio/ir/ir2.wav");</p>
  60 <p class="p5"><span class="Apple-tab-span">     </span>// irbuffer= Buffer.read(s, "/Volumes/data/audio/ir/ir.wav");</p>
  61 <p class="p5"><span class="Apple-tab-span">     </span>// this is a two second long hall IR</p>
  62 <p class="p5"><span class="Apple-tab-span">     </span>// irbuffer= Buffer.read(s, "/Volumes/data/audio/ir/bighall2.wav");</p>
  63 <p class="p7"><span class="Apple-tab-span">     </span></p>
  64 <p class="p2"><span class="Apple-tab-span">     </span></p>
  65 <p class="p5"><span class="s1"><span class="Apple-tab-span">    </span></span>// synthesise the honourable 'Dan Stowell' impulse response</p>
  66 <p class="p7"><span class="Apple-tab-span">     </span></p>
  67 <p class="p6"><span class="s3"><span class="Apple-tab-span">    </span></span>ir = ([1] ++0.dup(100) ++ ((1, 0.99998 .. 0).collect{<span class="s2">|f|</span> f =</p>
  68 <p class="p6"><span class="Apple-tab-span">     </span>f.squared.squared; f = if(f.coin){0}{f.squared}; f =</p>
  69 <p class="p6"><span class="Apple-tab-span">     </span>if(0.5.coin){0-f}{f} } * 0.1)).normalizeSum;</p>
  70 <p class="p5"><span class="s1"><span class="Apple-tab-span">    </span></span>// ir.plot;</p>
  71 <p class="p7"><span class="Apple-tab-span">     </span></p>
  72 <p class="p6"><span class="s3"><span class="Apple-tab-span">    </span></span>irbuffer = <span class="s2">Buffer</span>.loadCollection(s, ir);</p>
  73 <p class="p2"><span class="Apple-tab-span">     </span></p>
  74 <p class="p6"><span class="Apple-tab-span">     </span>s.sync;</p>
  75 <p class="p2"><span class="Apple-tab-span">     </span></p>
  76 <p class="p6"><span class="Apple-tab-span">     </span>bufsize= <span class="s2">PartConv</span>.calcBufSize(~fftsize, irbuffer);</p>
  77 <p class="p2"><span class="Apple-tab-span">     </span></p>
  78 <p class="p5"><span class="s1"><span class="Apple-tab-span">    </span></span>// ~numpartitions= PartConv.calcNumPartitions(~fftsize, irbuffer);</p>
  79 <p class="p7"><span class="Apple-tab-span">     </span></p>
  80 <p class="p6"><span class="Apple-tab-span">     </span>~irspectrum= <span class="s2">Buffer</span>.alloc(s, bufsize, 1);</p>
  81 <p class="p2"><span class="Apple-tab-span">     </span></p>
  82 <p class="p6"><span class="Apple-tab-span">     </span>~irspectrum.preparePartConv(irbuffer, ~fftsize);</p>
  83 <p class="p2"><span class="Apple-tab-span">     </span></p>
  84 <p class="p6"><span class="Apple-tab-span">     </span>s.sync;<span class="Apple-converted-space"> </span></p>
  85 <p class="p2"><span class="Apple-tab-span">     </span></p>
  86 <p class="p5"><span class="s1"><span class="Apple-tab-span">    </span>irbuffer.free; </span>// don't need time domain data anymore, just needed spectral version</p>
  87 <p class="p6">}.fork;</p>
  88 <p class="p2"><br></p>
  89 <p class="p6">};</p>
  90 <p class="p2"><br></p>
  91 <p class="p6">)</p>
  92 <p class="p2"><br></p>
  93 <p class="p2"><br></p>
  94 <p class="p2"><br></p>
  95 <p class="p8"><span class="s1">~target= </span><span class="s2">Buffer</span><span class="s1">.read(s, </span>"sounds/a11wlk01.wav"<span class="s1">);</span></p>
  96 <p class="p5">// ~target= Buffer.read(s, "sounds/break");</p>
  97 <p class="p2"><br></p>
  98 <p class="p6">(</p>
  99 <p class="p2"><br></p>
 100 <p class="p6">{ <span class="s2">var</span> input, kernel;</p>
 101 <p class="p2"><span class="Apple-tab-span">     </span></p>
 102 <p class="p6">input= <span class="s2">PlayBuf</span>.ar(1, ~target, loop:1);<span class="Apple-tab-span">       </span></p>
 103 <p class="p2"><br></p>
 104 <p class="p6"><span class="s2">Out</span>.ar(0, <span class="s2">PartConv</span>.ar(input, ~fftsize, ~irspectrum.bufnum, 0.5));</p>
 105 <p class="p6"><span class="Apple-converted-space"> </span>}.play;</p>
 106 <p class="p2"><br></p>
 107 <p class="p6">)</p>
 108 <p class="p2"><br></p>
 109 <p class="p2"><br></p>
 110 <p class="p5">// convolve with live input</p>
 111 <p class="p6">(</p>
 112 <p class="p2"><br></p>
 113 <p class="p6">{ <span class="s2">var</span> input, kernel;</p>
 114 <p class="p2"><span class="Apple-tab-span">     </span></p>
 115 <p class="p6">input= <span class="s2">SoundIn</span>.ar(0);<span class="Apple-tab-span">        </span></p>
 116 <p class="p2"><br></p>
 117 <p class="p6"><span class="s2">Out</span>.ar(0, <span class="s2">PartConv</span>.ar(input, ~fftsize, ~irspectrum.bufnum));</p>
 118 <p class="p6">}.play;</p>
 119 <p class="p6">)</p>
 120 <p class="p2"><br></p>
 121 <p class="p2"><br></p>
 122 <p class="p5">// should get back original impulse response (once every four seconds)</p>
 123 <p class="p6">(</p>
 124 <p class="p2"><br></p>
 125 <p class="p6">{ <span class="s2">var</span> input, kernel;</p>
 126 <p class="p2"><span class="Apple-tab-span">     </span></p>
 127 <p class="p6">input= <span class="s2">Impulse</span>.ar(0.25);<span class="Apple-tab-span">     </span></p>
 128 <p class="p2"><br></p>
 129 <p class="p6"><span class="s2">Out</span>.ar(0, <span class="s2">PartConv</span>.ar(input, ~fftsize, ~irspectrum.bufnum));</p>
 130 <p class="p6"><span class="Apple-converted-space"> </span>}.play;</p>
 131 <p class="p2"><br></p>
 132 <p class="p6">)</p>
 133 <p class="p2"><br></p>
 134 <p class="p2"><br></p>
 135 <p class="p9">// only free buffers once you're finished with examples</p>
 136 <p class="p9">// if you free whilst PartConv is still running, the server won't crash, but PartConv output will go to zero abruptly</p>
 137 <p class="p6">(</p>
 138 <p class="p10">~irspectrum.free;</p>
 139 <p class="p10">~target.free;</p>
 140 <p class="p10">currentEnvironment.clear;</p>
 141 <p class="p6">)</p>
 142 <p class="p2"><br></p>
 143 <p class="p2"><br></p>
 144 <p class="p2"><br></p>
 145 <p class="p2"><br></p>
 146 <p class="p2"><br></p>
 147 <p class="p2"><br></p>
 148 <p class="p2"><br></p>
 149 </body>
 150 </html>