comparison src/libsndfile-1.0.25/tests/dft_cmp.c @ 0:c7265573341e

Import initial set of sources

+/*
+** Copyright (C) 2002-2011 Erik de Castro Lopo <[e-mail]>
+**
+** 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.
+**
+** You should have received a copy of the GNU General Public License
+** along with this program; if not, write to the Free Software
+** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+*/
+
+#include	<stdio.h>
+#include	<stdlib.h>
+#include	<math.h>
+
+#include	"dft_cmp.h"
+#include	"utils.h"
+
+#ifndef		M_PI
+#define		M_PI		3.14159265358979323846264338
+#endif
+
+#define		DFT_SPEC_LENGTH		(DFT_DATA_LENGTH / 2)
+
+static void	dft_magnitude (const double *data, double *spectrum) ;
+static double calc_max_spectral_difference (const double *spec1, const double *spec2) ;
+
+/*--------------------------------------------------------------------------------
+**	Public functions.
+*/
+
+double
+dft_cmp_float (int linenum, const float *in_data, const float *test_data, int len, double target_snr, int allow_exit)
+{	static double orig [DFT_DATA_LENGTH] ;
+	static double test [DFT_DATA_LENGTH] ;
+	unsigned	k ;
+
+	if (len != DFT_DATA_LENGTH)
+	{	printf ("Error (line %d) : dft_cmp_float : Bad input array length.\n", linenum) ;
+		return 1 ;
+		} ;
+
+	for (k = 0 ; k < ARRAY_LEN (orig) ; k++)
+	{	test [k] = test_data [k] ;
+		orig [k] = in_data [k] ;
+		} ;
+
+	return dft_cmp_double (linenum, orig, test, len, target_snr, allow_exit) ;
+} /* dft_cmp_float */
+
+double
+dft_cmp_double (int linenum, const double *orig, const double *test, int len, double target_snr, int allow_exit)
+{	static double orig_spec [DFT_SPEC_LENGTH] ;
+	static double test_spec [DFT_SPEC_LENGTH] ;
+	double		snr ;
+
+	if (! orig || ! test)
+	{	printf ("Error (line %d) : dft_cmp_double : Bad input arrays.\n", linenum) ;
+		return 1 ;
+		} ;
+
+	if (len != DFT_DATA_LENGTH)
+	{	printf ("Error (line %d) : dft_cmp_double : Bad input array length.\n", linenum) ;
+		return 1 ;
+		} ;
+
+	dft_magnitude (orig, orig_spec) ;
+	dft_magnitude (test, test_spec) ;
+
+	snr = calc_max_spectral_difference (orig_spec, test_spec) ;
+
+	if (snr > target_snr)
+	{	printf ("\n\nLine %d: Actual SNR (% 4.1f) > target SNR (% 4.1f).\n\n", linenum, snr, target_snr) ;
+		oct_save_double	(orig, test, len) ;
+		if (allow_exit)
+			exit (1) ;
+		} ;
+
+	if (snr < -500.0)
+		snr = -500.0 ;
+
+	return snr ;
+} /* dft_cmp_double */
+
+/*--------------------------------------------------------------------------------
+**	Quick dirty calculation of magnitude spectrum for real valued data using
+**	Discrete Fourier Transform. Since the data is real, the DFT is only
+**	calculated for positive frequencies.
+*/
+
+static void
+dft_magnitude (const double *data, double *spectrum)
+{	static double cos_angle [DFT_DATA_LENGTH] = { 0.0 } ;
+	static double sin_angle [DFT_DATA_LENGTH] ;
+
+	double	real_part, imag_part ;
+	int		k, n ;
+
+	/* If sine and cosine tables haven't been initialised, do so. */
+	if (cos_angle [0] == 0.0)
+		for (n = 0 ; n < DFT_DATA_LENGTH ; n++)
+		{	cos_angle [n] = cos (2.0 * M_PI * n / DFT_DATA_LENGTH) ;
+			sin_angle [n] = -1.0 * sin (2.0 * M_PI * n / DFT_DATA_LENGTH) ;
+			} ;
+
+	/* DFT proper. Since the data is real, only generate a half spectrum. */
+	for (k = 1 ; k < DFT_SPEC_LENGTH ; k++)
+	{	real_part = 0.0 ;
+		imag_part = 0.0 ;
+
+		for (n = 0 ; n < DFT_DATA_LENGTH ; n++)
+		{	real_part += data [n] * cos_angle [(k * n) % DFT_DATA_LENGTH] ;
+			imag_part += data [n] * sin_angle [(k * n) % DFT_DATA_LENGTH] ;
+			} ;
+
+		spectrum [k] = sqrt (real_part * real_part + imag_part * imag_part) ;
+		} ;
+
+	spectrum [k] = 0.0 ;
+
+	spectrum [0] = spectrum [1] = spectrum [2] = spectrum [3] = spectrum [4] = 0.0 ;
+
+	return ;
+} /* dft_magnitude */
+
+static double
+calc_max_spectral_difference (const double *orig, const double *test)
+{	double orig_max = 0.0, max_diff = 0.0 ;
+	int	k ;
+
+	for (k = 0 ; k < DFT_SPEC_LENGTH ; k++)
+	{	if (orig_max < orig [k])
+			orig_max = orig [k] ;
+		if (max_diff < fabs (orig [k] - test [k]))
+			max_diff = fabs (orig [k] - test [k]) ;
+		} ;
+
+	if (max_diff < 1e-25)
+		return -500.0 ;
+
+	return 20.0 * log10 (max_diff / orig_max) ;
+} /* calc_max_spectral_difference */