1 /* 2 * Copyright (c) 2007, 2013, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 package com.sun.media.sound; 26 27 /** 28 * Lanczos interpolation resampler. 29 * 30 * @author Karl Helgason 31 */ 32 public final class SoftLanczosResampler extends SoftAbstractResampler { 33 34 float[][] sinc_table; 35 int sinc_table_fsize = 2000; 36 int sinc_table_size = 5; 37 int sinc_table_center = sinc_table_size / 2; 38 39 public SoftLanczosResampler() { 40 super(); 41 sinc_table = new float[sinc_table_fsize][]; 42 for (int i = 0; i < sinc_table_fsize; i++) { 43 sinc_table[i] = sincTable(sinc_table_size, -i 44 / ((float) sinc_table_fsize)); 45 } 46 } 47 48 // Normalized sinc function 49 public static double sinc(double x) { 50 return (x == 0.0) ? 1.0 : Math.sin(Math.PI * x) / (Math.PI * x); 51 } 52 53 // Generate sinc table 54 public static float[] sincTable(int size, float offset) { 55 int center = size / 2; 56 float[] w = new float[size]; 57 for (int k = 0; k < size; k++) { 58 float x = (-center + k + offset); 59 if (x < -2 || x > 2) 60 w[k] = 0; 61 else if (x == 0) 62 w[k] = 1; 63 else { 64 w[k] = (float)(2.0 * Math.sin(Math.PI * x) 65 * Math.sin(Math.PI * x / 2.0) 66 / ((Math.PI * x) * (Math.PI * x))); 67 } 68 } 69 return w; 70 } 71 72 public int getPadding() // must be at least half of sinc_table_size 73 { 74 return sinc_table_size / 2 + 2; 75 } 76 77 public void interpolate(float[] in, float[] in_offset, float in_end, 78 float[] startpitch, float pitchstep, float[] out, int[] out_offset, 79 int out_end) { 80 float pitch = startpitch[0]; 81 float ix = in_offset[0]; 82 int ox = out_offset[0]; 83 float ix_end = in_end; 84 int ox_end = out_end; 85 86 if (pitchstep == 0) { 87 while (ix < ix_end && ox < ox_end) { 88 int iix = (int) ix; 89 float[] sinc_table 90 = this.sinc_table[(int) ((ix - iix) * sinc_table_fsize)]; 91 int xx = iix - sinc_table_center; 92 float y = 0; 93 for (int i = 0; i < sinc_table_size; i++, xx++) 94 y += in[xx] * sinc_table[i]; 95 out[ox++] = y; 96 ix += pitch; 97 } 98 } else { 99 while (ix < ix_end && ox < ox_end) { 100 int iix = (int) ix; 101 float[] sinc_table 102 = this.sinc_table[(int) ((ix - iix) * sinc_table_fsize)]; 103 int xx = iix - sinc_table_center; 104 float y = 0; 105 for (int i = 0; i < sinc_table_size; i++, xx++) 106 y += in[xx] * sinc_table[i]; 107 out[ox++] = y; 108 109 ix += pitch; 110 pitch += pitchstep; 111 } 112 } 113 in_offset[0] = ix; 114 out_offset[0] = ox; 115 startpitch[0] = pitch; 116 117 } 118 }