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* 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).
*
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* 2 along with this work; if not, write to the Free Software Foundation,
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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;
}
}