/* * Copyright (c) 2007 by Damien Di Fede <ddf@compartmental.net> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU Library General Public License as published * by the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU Library General Public License for more details. * * You should have received a copy of the GNU Library General Public * License along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ package ddf.minim.effects; /** * LowPassSP is a single pole low pass filter. It is not super great, but it gets the job * done. * * @author Damien Di Fede * */ public class LowPassSP extends IIRFilter { /** * Constructs a low pass filter with a cutoff frequency of <code>freq</code> * that will be used to filter audio recorded at <code>sampleRate</code>. * * @param freq * the cutoff frequency * @param sampleRate * the sample rate of the audio that will be filtered */ public LowPassSP(float freq, float sampleRate) { super(freq, sampleRate); } protected void calcCoeff() { float fracFreq = frequency()/sampleRate(); float x = (float)Math.exp(-2*Math.PI*fracFreq); a = new float[] { 1 - x }; b = new float[] { x }; } }