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diff --git a/src/com/jsyn/unitgen/SpectralFFT.java b/src/com/jsyn/unitgen/SpectralFFT.java
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+++ b/src/com/jsyn/unitgen/SpectralFFT.java
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+/*
+ * Copyright 2013 Phil Burk, Mobileer Inc
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.jsyn.unitgen;
+
+import java.util.Arrays;
+
+import com.jsyn.data.SpectralWindow;
+import com.jsyn.data.Spectrum;
+import com.jsyn.ports.UnitInputPort;
+import com.jsyn.ports.UnitSpectralOutputPort;
+import com.softsynth.math.FourierMath;
+
+/**
+ * Periodically transform the input signal using an FFT. Output complete spectra.
+ * 
+ * @author Phil Burk (C) 2013 Mobileer Inc
+ * @version 016
+ * @see SpectralIFFT
+ * @see Spectrum
+ * @see SpectralFilter
+ */
+public class SpectralFFT extends UnitGenerator {
+    public UnitInputPort input;
+    /**
+     * Provides complete complex spectra when the FFT completes.
+     */
+    public UnitSpectralOutputPort output;
+    private double[] buffer;
+    private int cursor;
+    private SpectralWindow window = RectangularWindow.getInstance();
+    private int sizeLog2;
+    private int offset;
+    private boolean running;
+
+    /* Define Unit Ports used by connect() and set(). */
+    public SpectralFFT() {
+        this(Spectrum.DEFAULT_SIZE_LOG_2);
+    }
+
+    /**
+     * @param sizeLog2 for example, pass 10 to get a 1024 bin FFT
+     */
+    public SpectralFFT(int sizeLog2) {
+        addPort(input = new UnitInputPort("Input"));
+        addPort(output = new UnitSpectralOutputPort("Output", 1 << sizeLog2));
+        setSizeLog2(sizeLog2);
+    }
+
+    /**
+     * Please do not change the size of the FFT while JSyn is running.
+     * 
+     * @param sizeLog2 for example, pass 9 to get a 512 bin FFT
+     */
+    public void setSizeLog2(int sizeLog2) {
+        this.sizeLog2 = sizeLog2;
+        output.setSize(1 << sizeLog2);
+        buffer = output.getSpectrum().getReal();
+        cursor = 0;
+    }
+
+    public int getSizeLog2() {
+        return sizeLog2;
+    }
+
+    @Override
+    public void generate(int start, int limit) {
+        if (!running) {
+            int mask = (1 << sizeLog2) - 1;
+            if (((getSynthesisEngine().getFrameCount() - offset) & mask) == 0) {
+                running = true;
+                cursor = 0;
+            }
+        }
+        // Don't use "else" because "running" may have changed in above block.
+        if (running) {
+            double[] inputs = input.getValues();
+            for (int i = start; i < limit; i++) {
+                buffer[cursor] = inputs[i] * window.get(cursor);
+                ++cursor;
+                // When it is full, do the FFT.
+                if (cursor == buffer.length) {
+                    Spectrum spectrum = output.getSpectrum();
+                    Arrays.fill(spectrum.getImaginary(), 0.0);
+                    FourierMath.fft(buffer.length, spectrum.getReal(), spectrum.getImaginary());
+                    output.advance();
+                    cursor = 0;
+                }
+            }
+        }
+    }
+
+    public SpectralWindow getWindow() {
+        return window;
+    }
+
+    /**
+     * Multiply input data by this window before doing the FFT. The default is a RectangularWindow.
+     */
+    public void setWindow(SpectralWindow window) {
+        this.window = window;
+    }
+
+    /**
+     * The FFT will be performed on a frame that is a multiple of the size plus this offset.
+     * 
+     * @param offset
+     */
+    public void setOffset(int offset) {
+        this.offset = offset;
+    }
+
+    public int getOffset() {
+        return offset;
+    }
+
+}