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 26 package com.sun.media.sound; 27 28 /** 29 * Hann windowed sinc interpolation resampler with anti-alias filtering. 30 * 31 * Using 30 points for the interpolation. 32 * 33 * @author Karl Helgason 34 */ 35 public final class SoftSincResampler extends SoftAbstractResampler { 36 37 float[][][] sinc_table; 38 int sinc_scale_size = 100; 39 int sinc_table_fsize = 800; 40 int sinc_table_size = 30; 41 int sinc_table_center = sinc_table_size / 2; 42 SoftSincResampler()43 public SoftSincResampler() { 44 super(); 45 sinc_table = new float[sinc_scale_size][sinc_table_fsize][]; 46 for (int s = 0; s < sinc_scale_size; s++) { 47 float scale = (float) (1.0 / (1.0 + Math.pow(s, 1.1) / 10.0)); 48 for (int i = 0; i < sinc_table_fsize; i++) { 49 sinc_table[s][i] = sincTable(sinc_table_size, 50 -i / ((float)sinc_table_fsize), scale); 51 } 52 } 53 } 54 55 // Normalized sinc function sinc(double x)56 public static double sinc(double x) { 57 return (x == 0.0) ? 1.0 : Math.sin(Math.PI * x) / (Math.PI * x); 58 } 59 60 // Generate hann window suitable for windowing sinc wHanning(int size, float offset)61 public static float[] wHanning(int size, float offset) { 62 float[] window_table = new float[size]; 63 for (int k = 0; k < size; k++) { 64 window_table[k] = (float)(-0.5 65 * Math.cos(2.0 * Math.PI * (double)(k + offset) 66 / (double) size) + 0.5); 67 } 68 return window_table; 69 } 70 71 // Generate sinc table sincTable(int size, float offset, float scale)72 public static float[] sincTable(int size, float offset, float scale) { 73 int center = size / 2; 74 float[] w = wHanning(size, offset); 75 for (int k = 0; k < size; k++) 76 w[k] *= sinc((-center + k + offset) * scale) * scale; 77 return w; 78 } 79 80 @Override getPadding()81 public int getPadding() // must be at least half of sinc_table_size 82 { 83 return sinc_table_size / 2 + 2; 84 } 85 86 @Override interpolate(float[] in, float[] in_offset, float in_end, float[] startpitch, float pitchstep, float[] out, int[] out_offset, int out_end)87 public void interpolate(float[] in, float[] in_offset, float in_end, 88 float[] startpitch, float pitchstep, float[] out, int[] out_offset, 89 int out_end) { 90 float pitch = startpitch[0]; 91 float ix = in_offset[0]; 92 int ox = out_offset[0]; 93 float ix_end = in_end; 94 int ox_end = out_end; 95 int max_p = sinc_scale_size - 1; 96 if (pitchstep == 0) { 97 98 int p = (int) ((pitch - 1) * 10.0f); 99 if (p < 0) 100 p = 0; 101 else if (p > max_p) 102 p = max_p; 103 float[][] sinc_table_f = this.sinc_table[p]; 104 while (ix < ix_end && ox < ox_end) { 105 int iix = (int) ix; 106 float[] sinc_table = 107 sinc_table_f[(int)((ix - iix) * sinc_table_fsize)]; 108 int xx = iix - sinc_table_center; 109 float y = 0; 110 for (int i = 0; i < sinc_table_size; i++, xx++) 111 y += in[xx] * sinc_table[i]; 112 out[ox++] = y; 113 ix += pitch; 114 } 115 } else { 116 while (ix < ix_end && ox < ox_end) { 117 int iix = (int) ix; 118 int p = (int) ((pitch - 1) * 10.0f); 119 if (p < 0) 120 p = 0; 121 else if (p > max_p) 122 p = max_p; 123 float[][] sinc_table_f = this.sinc_table[p]; 124 125 float[] sinc_table = 126 sinc_table_f[(int)((ix - iix) * sinc_table_fsize)]; 127 int xx = iix - sinc_table_center; 128 float y = 0; 129 for (int i = 0; i < sinc_table_size; i++, xx++) 130 y += in[xx] * sinc_table[i]; 131 out[ox++] = y; 132 133 ix += pitch; 134 pitch += pitchstep; 135 } 136 } 137 in_offset[0] = ix; 138 out_offset[0] = ox; 139 startpitch[0] = pitch; 140 } 141 } 142