shithub: libsamplerate

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Add log magnitude calculations.

--- a/FIR-POLY/fir_interp.cc

+++ b/FIR-POLY/fir_interp.cc

@@ -69,6 +69,7 @@

 	double window [2048] ;

 	double filter [2048] ;

 	double mag [1024] ;

+	double logmag [1024] ;

 	double phase [1024] ;

 } FIR_INTERP ;

@@ -128,7 +129,7 @@

 static double

 evaluate_filter (FIR_INTERP *interp)

 {

-	mag_spectrum (interp->filter, ARRAY_LEN (interp->filter), interp->mag, interp->phase) ;

+	mag_spectrum (interp->filter, ARRAY_LEN (interp->filter), interp->mag, interp->logmag, interp->phase) ;

 	return 1.0 ;

 } /* evaluate_filter */

@@ -359,6 +360,14 @@

 	for (k = 0 ; k < ARRAY_LEN (interp->mag) ; k++)

 		fprintf (file, "% f\n", interp->mag [k]) ;

+

+	fprintf (file, "# name: logmag\n") ;

+	fprintf (file, "# type: matrix\n") ;

+	fprintf (file, "# rows: %d\n", ARRAY_LEN (interp->logmag)) ;

+	fprintf (file, "# columns: 1\n") ;

+

+	for (k = 0 ; k < ARRAY_LEN (interp->logmag) ; k++)

+		fprintf (file, "% f\n", interp->logmag [k]) ;

 	fprintf (file, "# name: phase\n") ;

 	fprintf (file, "# type: matrix\n") ;

--- a/FIR-POLY/mag_spectrum.cc

+++ b/FIR-POLY/mag_spectrum.cc

@@ -26,7 +26,7 @@

 #include <fftw3.h>

 void

-mag_spectrum (double *input, int len, double *magnitude, double *phase)

+mag_spectrum (double *input, int len, double *magnitude, double *logmag, double *phase)

 {	static fftw_plan plan = NULL ;

 	static int saved_len = -1 ;

 	static double *fft_data = NULL ;

@@ -61,6 +61,7 @@

 	maxval = 0.0 ;

 	for (k = 0 ; k < len / 2 ; k++)

 	{	magnitude [k] = sqrt (fft_data [k] * fft_data [k] + fft_data [len - k - 1] * fft_data [len - k - 1]) ;

+		logmag [k] = (magnitude [k] < 1e-10) ? -200.0 : 20 * log10 (magnitude [k]) ;

 		phase [k] = atan2 (fft_data [len - k - 1], fft_data [k]) ;

 		} ;

--- a/FIR-POLY/mag_spectrum.hh

+++ b/FIR-POLY/mag_spectrum.hh

@@ -18,7 +18,7 @@

 ** written permission of Erik de Castro Lopo.

 */

-void mag_spectrum (double *input, int len, double *magnitude, double *phase) ;

+void mag_spectrum (double *input, int len, double *magnitude, double *logmag, double *phase) ;

 // Do not edit or modify anything in this comment block.

 // The following line is a file identity tag for the GNU Arch