/* * Copyright (c) 2007, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code 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 General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */package com.sun.media.sound; /** * Lanczos interpolation resampler. * * @author Karl Helgason */public class SoftLanczosResampler extends SoftAbstractResampler {     float[][] sinc_table;    int sinc_table_fsize = 2000;    int sinc_table_size = 5;    int sinc_table_center = sinc_table_size / 2;     public SoftLanczosResampler() {        super();        sinc_table = new float[sinc_table_fsize][];        for (int i = 0; i < sinc_table_fsize; i++) {            sinc_table[i] = sincTable(sinc_table_size, -i                            / ((float) sinc_table_fsize));        }    }     // Normalized sinc function    public static double sinc(double x) {        return (x == 0.0) ? 1.0 : Math.sin(Math.PI * x) / (Math.PI * x);    }     // Generate sinc table    public static float[] sincTable(int size, float offset) {        int center = size / 2;        float[] w = new float[size];        for (int k = 0; k < size; k++) {            float x = (-center + k + offset);            if (x < -2 || x > 2)                w[k] = 0;            else if (x == 0)                w[k] = 1;            else {                w[k] = (float)(2.0 * Math.sin(Math.PI * x)                                * Math.sin(Math.PI * x / 2.0)                                / ((Math.PI * x) * (Math.PI * x)));            }        }        return w;    }     public int getPadding() // must be at least half of sinc_table_size    {        return sinc_table_size / 2 + 2;    }     public void interpolate(float[] in, float[] in_offset, float in_end,            float[] startpitch, float pitchstep, float[] out, int[] out_offset,            int out_end) {        float pitch = startpitch[0];        float ix = in_offset[0];        int ox = out_offset[0];        float ix_end = in_end;        int ox_end = out_end;         if (pitchstep == 0) {            while (ix < ix_end && ox < ox_end) {                int iix = (int) ix;                float[] sinc_table                        = this.sinc_table[(int) ((ix - iix) * sinc_table_fsize)];                int xx = iix - sinc_table_center;                float y = 0;                for (int i = 0; i < sinc_table_size; i++, xx++)                    y += in[xx] * sinc_table[i];                out[ox++] = y;                ix += pitch;            }        } else {            while (ix < ix_end && ox < ox_end) {                int iix = (int) ix;                float[] sinc_table                        = this.sinc_table[(int) ((ix - iix) * sinc_table_fsize)];                int xx = iix - sinc_table_center;                float y = 0;                for (int i = 0; i < sinc_table_size; i++, xx++)                    y += in[xx] * sinc_table[i];                out[ox++] = y;                 ix += pitch;                pitch += pitchstep;            }        }        in_offset[0] = ix;        out_offset[0] = ox;        startpitch[0] = pitch;     }}