SRC テスト
Fork

(Original repository, No fork origin)

提交

FIRフィルタまで動作検証済み

--- a/src_test/main.c

+++ b/src_test/main.c

		@@ -9,23 +9,38 @@
9	9	#include <math.h>
10	10	#include <stdio.h>
11	11	#define CUTOFF (0.475)
	12	+#define TAPS 127
12	13
13	14	/* x : [0, 1.0) */
14	15	double hanning(double x);
15	16	/* cutoff : normalized frequency where cutoff freq / sampling freq */
16	17	double sinc(double x, double cutoff);
	18	+ /* put a sample into the delayline */
	19	+void putSample( double aSample, double aDelayline[] );
	20	+ /* calc the convolution */
	21	+double convolute ( double aDelayline[], double offset );
17	22
18	23	double h( double x, int lenght);
19	24
	25	+double delayline[TAPS];
	26	+
	27	+
	28	+
20	29	int main(void)
21	30	{
22	31
23		- int i;
	32	+ int readsize;
	33	+ float aSample;
24	34
25		- for ( i=0; i<127; i++)
	35	+ while ( 1)
26	36	{
27		-// printf( "%f\n", sinc(i, CUTOFF));
28		- printf( "%f\n", h( i, 127));
	37	+ readsize = fread((void *)&aSample, sizeof(float), 1, stdin);
	38	+ if ( readsize < 1)
	39	+ break;
	40	+ putSample(aSample, delayline);
	41	+ aSample = convolute(delayline, 0.25);
	42	+ fwrite( &aSample, sizeof(float), 1, stdout );
	43	+
29	44	}
30	45
31	46	return 0;

		@@ -36,14 +51,10 @@ int main(void)
36	51	double h( double x, int length)
37	52	{
38	53	int center;
39		- double fractional;
40		-
41		- fractional = x - floor(x);
42	54
43	55	center = (length -1 )/2;
44	56
45		- return sinc( x - center, CUTOFF );
46		-// return hanning ( x / ( length - 1 ));
	57	+ return sinc( x - center, CUTOFF )* hanning ( x / ( length - 1 ));
47	58	}
48	59
49	60	double sinc(double x, double cutoff )

		@@ -58,3 +69,26 @@ double hanning(double x)
58	69	else
59	70	return 0.0;
60	71	}
	72	+
	73	+
	74	+void putSample( double aSample, double aDelayline[] )
	75	+{
	76	+ int i;
	77	+
	78	+ /* Shift the sample in the line */
	79	+ for ( i=TAPS-1; i>0; i--)
	80	+ aDelayline[i] = aDelayline[i-1];
	81	+
	82	+ aDelayline[0] = aSample;
	83	+}
	84	+
	85	+double convolute ( double aDelayline[], double offset )
	86	+{
	87	+ int i;
	88	+ double sum = 0.0;
	89	+
	90	+ for ( i=0; i< TAPS; i++ )
	91	+ sum += aDelayline[i] * h(i+offset, TAPS);
	92	+
	93	+ return sum;
	94	+}