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Added FIR filter to libfilter

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This commit is contained in:
Andreas Eversberg
2020-02-27 18:47:54 +01:00
parent 55a5a4ea2b
commit 5070bc70bd
4 changed files with 263 additions and 1 deletions
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42
src/test/test_filter.c
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@@ -4,6 +4,7 @@
#include <string.h>
#include "../libsample/sample.h"
#include "../libfilter/iir_filter.h"
#include "../libfilter/fir_filter.h"
#include "../libdebug/debug.h"
#define level2db(level) (20 * log10(level))
@@ -40,6 +41,7 @@ int main(void)
{
iir_filter_t filter_low;
iir_filter_t filter_high;
fir_filter_t *fir_low/*, *fir_high*/;
sample_t samples[SAMPLERATE];
double level;
int iter = 2;
@@ -102,6 +104,46 @@ int main(void)
printf("\n");
}
double freq = 2000.0;
double tb = 400.0;
printf("testing low-pass FIR filter with %.0fHz transition bandwidth\n", tb);
fir_low = fir_lowpass_init(SAMPLERATE, freq, tb);
printf("Using %d taps\n", fir_low->ntaps);
for (i = 0; i < 4001; i += 100) {
gen_samples(samples, (double)i);
fir_process(fir_low, samples, SAMPLERATE);
level = get_level(samples);
printf("%s%s%4d Hz: %.1f dB", debug_amplitude(level), debug_db(level), i, level2db(level));
if (i == freq)
printf(" cutoff\n");
else
printf("\n");
}
fir_exit(fir_low);
#if 0
double freq1 = 1000.0, freq2 = 2000.0;
tb = 100.0;
printf("testing two-pass FIR filter\n");
fir_high = fir_twopass_init(SAMPLERATE, freq1, freq2, tb);
printf("Using %d taps\n", fir_high->ntaps);
for (i = 0; i < 4001; i += 100) {
gen_samples(samples, (double)i);
fir_process(fir_high, samples, SAMPLERATE);
level = get_level(samples);
printf("%s%s%4d Hz: %.1f dB", debug_amplitude(level), debug_db(level), i, level2db(level));
if (i == freq1 || i == freq2)
printf(" cutoff\n");
else
printf("\n");
}
fir_exit(fir_high);
#endif
return 0;
}