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  * A resampler that uses third-order (cubic) interpolation.
  30  *
  31  * @author Karl Helgason
  32  */
  33 public final class SoftCubicResampler extends SoftAbstractResampler {
  34 
  35     @Override
  36     public int getPadding() {
  37         return 3;
  38     }
  39 
  40     @Override
  41     public void interpolate(float[] in, float[] in_offset, float in_end,
  42                             float[] startpitch, float pitchstep, float[] out, int[] out_offset,
  43                             int out_end) {
  44         float pitch = startpitch[0];
  45         float ix = in_offset[0];
  46         int ox = out_offset[0];
  47         float ix_end = in_end;
  48         int ox_end = out_end;
  49         if (pitchstep == 0) {
  50             while (ix < ix_end && ox < ox_end) {
  51                 int iix = (int) ix;
  52                 float fix = ix - iix;
  53                 float y0 = in[iix - 1];
  54                 float y1 = in[iix];
  55                 float y2 = in[iix + 1];
  56                 float y3 = in[iix + 2];
  57                 float a0 = y3 - y2 + y1 - y0;
  58                 float a1 = y0 - y1 - a0;
  59                 float a2 = y2 - y0;
  60                 float a3 = y1;
  61                 //float fix2 = fix * fix;
  62                 //out[ox++] = (a0 * fix + a1) * fix2 + (a2 * fix + a3);
  63                 out[ox++] = ((a0 * fix + a1) * fix + a2) * fix + a3;
  64                 ix += pitch;
  65             }
  66         } else {
  67             while (ix < ix_end && ox < ox_end) {
  68                 int iix = (int) ix;
  69                 float fix = ix - iix;
  70                 float y0 = in[iix - 1];
  71                 float y1 = in[iix];
  72                 float y2 = in[iix + 1];
  73                 float y3 = in[iix + 2];
  74                 float a0 = y3 - y2 + y1 - y0;
  75                 float a1 = y0 - y1 - a0;
  76                 float a2 = y2 - y0;
  77                 float a3 = y1;
  78                 //float fix2 = fix * fix;
  79                 //out[ox++] = (a0 * fix + a1) * fix2 + (a2 * fix + a3);
  80                 out[ox++] = ((a0 * fix + a1) * fix + a2) * fix + a3;
  81                 ix += pitch;
  82                 pitch += pitchstep;
  83             }
  84         }
  85         in_offset[0] = ix;
  86         out_offset[0] = ox;
  87         startpitch[0] = pitch;
  88 
  89     }
  90 }