| /* |
| * Copyright (c) 2007, 2013, 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 final 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; |
| |
| } |
| } |