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/* * 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; /** * Hann windowed sinc interpolation resampler with anti-alias filtering. * * Using 30 points for the interpolation. * * @author Karl Helgason */public class SoftSincResampler extends SoftAbstractResampler {     float[][][] sinc_table;    int sinc_scale_size = 100;    int sinc_table_fsize = 800;    int sinc_table_size = 30;    int sinc_table_center = sinc_table_size / 2;     public SoftSincResampler() {        super();        sinc_table = new float[sinc_scale_size][sinc_table_fsize][];        for (int s = 0; s < sinc_scale_size; s++) {            float scale = (float) (1.0 / (1.0 + Math.pow(s, 1.1) / 10.0));            for (int i = 0; i < sinc_table_fsize; i++) {                sinc_table[s][i] = sincTable(sinc_table_size,                        -i / ((float)sinc_table_fsize), scale);            }        }    }     // Normalized sinc function    public static double sinc(double x) {        return (x == 0.0) ? 1.0 : Math.sin(Math.PI * x) / (Math.PI * x);    }     // Generate hann window suitable for windowing sinc    public static float[] wHanning(int size, float offset) {        float[] window_table = new float[size];        for (int k = 0; k < size; k++) {            window_table[k] = (float)(-0.5                    * Math.cos(2.0 * Math.PI * (double)(k + offset)                        / (double) size) + 0.5);        }        return window_table;    }     // Generate sinc table    public static float[] sincTable(int size, float offset, float scale) {        int center = size / 2;        float[] w = wHanning(size, offset);        for (int k = 0; k < size; k++)            w[k] *= sinc((-center + k + offset) * scale) * scale;        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;        int max_p = sinc_scale_size - 1;        if (pitchstep == 0) {             int p = (int) ((pitch - 1) * 10.0f);            if (p < 0)                p = 0;            else if (p > max_p)                p = max_p;            float[][] sinc_table_f = this.sinc_table[p];            while (ix < ix_end && ox < ox_end) {                int iix = (int) ix;                float[] sinc_table =                        sinc_table_f[(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;                int p = (int) ((pitch - 1) * 10.0f);                if (p < 0)                    p = 0;                else if (p > max_p)                    p = max_p;                float[][] sinc_table_f = this.sinc_table[p];                 float[] sinc_table =                        sinc_table_f[(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;     }}