Help/UGens/FFT/IFFT.html

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  27 <p class="p1"><span class="s1"><b>IFFT<span class="Apple-tab-span">     </span><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span></b></span><b>Inverse Fast Fourier Transform</b></p>
  28 <p class="p2"><br></p>
  29 <p class="p3"><span class="s2"><b>Inherits from: </b><a href="../../Core/Object.html"><b>Object</b></a></span><b> : </b><a href="../../Core/Kernel/AbstractFunction.html"><b>AbstractFunction</b></a><b> : </b><a href="../UGen.html"><b>UGen</b></a><b><span class="Apple-converted-space"> </span></b></p>
  30 <p class="p2"><br></p>
  31 <p class="p2"><br></p>
  32 <p class="p1"><b>IFFT.new(chain, wintype, winsize)</b></p>
  33 <p class="p1"><b>IFFT.ar(chain, wintype, winsize)</b></p>
  34 <p class="p1"><b>IFFT.kr(chain, wintype, winsize)</b></p>
  35 <p class="p2"><br></p>
  36 <p class="p2"><br></p>
  37 <p class="p1">The fast fourier transform analyzes the frequency content of a signal. The IFFT UGen converts this <i>frequency-domain</i> information back into <i>time-domain</i> audio data. Most often this is used as the end of a process which begins with FFT, followed by frequency-domain processing using PV (phase-vocoder) UGens, followed by IFFT.</p>
  38 <p class="p2"><br></p>
  39 <p class="p1"><b>chain</b> - The FFT "chain" signal coming originally from an FFT UGen, perhaps via other PV UGens.</p>
  40 <p class="p1"><b>wintype</b> - defines how the data is windowed:</p>
  41 <p class="p1"><span class="Apple-tab-span">     </span>-1 is for <b><i>rectangular</i></b> windowing, simple but typically not recommended;<span class="Apple-converted-space"> </span></p>
  42 <p class="p1"><span class="Apple-tab-span">     </span>0 (the default) is for <b><i>Sine</i></b> windowing, typically recommended for phase-vocoder work;<span class="Apple-converted-space"> </span></p>
  43 <p class="p1"><span class="Apple-tab-span">     </span>1 is for <b><i>Hann</i></b> windowing, typically recommended for analysis work.</p>
  44 <p class="p1"><b>winsize</b> - can be used to account for zero-padding, in the same way as the FFT UGen.</p>
  45 <p class="p2"><br></p>
  46 <p class="p1">The IFFT UGen converts the FFT data in-place (in the original FFT buffer) and overlap-adds the result to produce a continuous signal at its output.</p>
  47 <p class="p2"><br></p>
  48 <p class="p1"><b>See also:</b> <a href="FFT Overview.html"><span class="s3">FFT Overview</span></a>, <a href="FFT.html"><span class="s4">FFT</span></a>, <a href="PV_Copy.html"><span class="s4">PV_Copy</span></a></p>
  49 <p class="p4"><br></p>
  50 <p class="p4"><br></p>
  51 <p class="p4"><br></p>
  52 <p class="p5">// example</p>
  53 <p class="p6">(</p>
  54 <p class="p6">{ <span class="s5">var</span> in, chain;</p>
  55 <p class="p6"><span class="Apple-tab-span">     </span>in = <span class="s5">WhiteNoise</span>.ar(0.05);</p>
  56 <p class="p6"><span class="Apple-tab-span">     </span>chain = <span class="s5">FFT</span>(<span class="s5">LocalBuf</span>(2048), in);</p>
  57 <p class="p6"><span class="Apple-tab-span">     </span>chain.inspect; <span class="s6">// its an FFT</span></p>
  58 <p class="p6"><span class="Apple-tab-span">     </span><span class="s5">Out</span>.ar(0,<span class="Apple-converted-space"> </span></p>
  59 <p class="p5"><span class="s2"><span class="Apple-tab-span">    </span><span class="Apple-tab-span">    </span></span><span class="s5">IFFT</span><span class="s2">(chain) </span>// inverse FFT</p>
  60 <p class="p6"><span class="Apple-tab-span">     </span>);</p>
  61 <p class="p6">}.play</p>
  62 <p class="p6">)</p>
  63 <p class="p4"><br></p>
  64 <p class="p1">See <a href="FFT.html"><span class="s7">FFT</span></a> for more examples.</p>
  65 <p class="p2"><br></p>
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