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
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
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
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
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
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
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 }