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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 com.jsyn.data.SpectralWindow;
import com.jsyn.data.Spectrum;
import com.jsyn.ports.UnitOutputPort;
import com.jsyn.ports.UnitSpectralInputPort;
import com.softsynth.math.FourierMath;
/**
* Periodically transform the input signal using an Inverse FFT.
*
* @author Phil Burk (C) 2013 Mobileer Inc
* @version 016
* @see SpectralFFT
*/
public class SpectralIFFT extends UnitGenerator {
public UnitSpectralInputPort input;
public UnitOutputPort output;
private Spectrum localSpectrum;
private double[] buffer;
private int cursor;
private SpectralWindow window = RectangularWindow.getInstance();
/* Define Unit Ports used by connect() and set(). */
public SpectralIFFT() {
addPort(output = new UnitOutputPort());
addPort(input = new UnitSpectralInputPort("Input"));
}
@Override
public void generate(int start, int limit) {
double[] outputs = output.getValues();
if (buffer == null) {
if (input.isAvailable()) {
Spectrum spectrum = input.getSpectrum();
int size = spectrum.size();
localSpectrum = new Spectrum(size);
buffer = localSpectrum.getReal();
cursor = 0;
} else {
for (int i = start; i < limit; i++) {
outputs[i] = 0.0;
}
}
}
if (buffer != null) {
for (int i = start; i < limit; i++) {
if (cursor == 0) {
Spectrum spectrum = input.getSpectrum();
spectrum.copyTo(localSpectrum);
FourierMath.ifft(buffer.length, localSpectrum.getReal(),
localSpectrum.getImaginary());
}
outputs[i] = buffer[cursor] * window.get(cursor);
cursor += 1;
if (cursor == buffer.length) {
cursor = 0;
}
}
}
}
public SpectralWindow getWindow() {
return window;
}
/**
* Multiply output data by this window after doing the FFT. The default is a RectangularWindow.
*/
public void setWindow(SpectralWindow window) {
this.window = window;
}
}
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