/*
* Copyright (C) 2004 Steve Harris
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 for more details.
*
* $Id: distortion-test.c $
*/
#include <unistd.h>
#include <string.h>
#include <math.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <complex.h>
#include <fftw3.h>
#include "gdither.h"
#define SIZE 16384
#ifndef M_PI
#define M_PI 3.1415926
#endif
float in[SIZE];
int32_t out[SIZE];
double sin_tbl[SIZE];
double sinless_tbl[SIZE];
void mkdata(GDitherType dt, const char *desc);
int main(int argc, char *argv[])
{
int i;
for (i=0; i<SIZE; i++) {
sin_tbl[i] = sin((double)i * M_PI * 0.05) * 0.01;
in[i] = (float)sin_tbl[i];
}
//mkdata(GDitherNone, "no dithering");
//mkdata(GDitherRect, "rectangular dithering");
//mkdata(GDitherTri, "triangular dithering");
mkdata(GDitherShaped, "noise-shaped dithering");
return 0;
}
void mkdata(GDitherType dt, const char *desc)
{
int i;
GDither *ds = gdither_new(dt, 1, 16, 0);
int16_t out16[SIZE];
fftw_plan plan_rc;
fftw_complex *freq = fftw_malloc(sizeof(fftw_complex) * (SIZE + 1));
double amp;
plan_rc = fftw_plan_dft_r2c_1d(SIZE, sinless_tbl, freq, FFTW_PRESERVE_INPUT);
gdither_runf(ds, 0, SIZE, in, out16);
for (i=0; i<SIZE; i++) {
sinless_tbl[i] = ((double)out16[i] / 32768.0) - sin_tbl[i];
sinless_tbl[i] *= -0.5 * cos(2.0f * M_PI * (float) i /
(float) SIZE) + 0.5;
}
fftw_execute(plan_rc);
for (i=2; i<SIZE/2; i++) {
amp = 20.0 * log10(cabs(freq[i]));
printf("%f\t%g\n", 48000.0 / (double)SIZE * (double)i, amp);
}
}
/* vi:set ts=8 sts=4 sw=4: */