80 lines
1.8 KiB
C
80 lines
1.8 KiB
C
#include <stdio.h>
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#include <stdint.h>
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#include <math.h>
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#include <string.h>
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#include "../libsample/sample.h"
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#include "../libfilter/iir_filter.h"
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#include "../libemphasis/emphasis.h"
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#include "../libdebug/debug.h"
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#define level2db(level) (20 * log10(level))
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#define db2level(db) pow(10, (double)db / 20.0)
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#define SAMPLERATE 48000
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static double get_level(sample_t *samples)
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{
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int i;
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double envelope = 0;
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for (i = SAMPLERATE/2; i < SAMPLERATE; i++) {
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if (samples[i] > envelope)
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envelope = samples[i];
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}
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return envelope;
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}
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static void gen_samples(sample_t *samples, double freq)
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{
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int i;
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double value;
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for (i = 0; i < SAMPLERATE; i++) {
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value = cos(2.0 * M_PI * freq / (double)SAMPLERATE * (double)i);
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samples[i] = value;
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}
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}
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int num_kanal;
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int main(void)
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{
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emphasis_t estate;
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double cut_off = CUT_OFF_EMPHASIS_DEFAULT;
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sample_t samples[SAMPLERATE];
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double level;
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double i;
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init_emphasis(&estate, SAMPLERATE, cut_off, CUT_OFF_HIGHPASS_DEFAULT, CUT_OFF_LOWPASS_DEFAULT);
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printf("testing pre-emphasis filter with cut-off frequency %.1f\n", cut_off);
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for (i = 31.25; i < 4001; i = i * sqrt(sqrt(2.0))) {
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gen_samples(samples, (double)i);
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pre_emphasis(&estate, samples, SAMPLERATE);
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level = get_level(samples);
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printf("%s%.0f Hz: %.1f dB", debug_db(level), i, level2db(level));
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if ((int)round(i) == 1000)
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printf(" level=%.6f\n", level);
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else
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printf("\n");
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}
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printf("testing de-emphasis filter with cut-off frequency %.1f\n", cut_off);
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for (i = 31.25; i < 4001; i = i * sqrt(sqrt(2.0))) {
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gen_samples(samples, (double)i);
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dc_filter(&estate, samples, SAMPLERATE);
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de_emphasis(&estate, samples, SAMPLERATE);
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level = get_level(samples);
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printf("%s%.0f Hz: %.1f dB", debug_db(level), i, level2db(level));
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if ((int)round(i) == 1000)
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printf(" level=%.6f\n", level);
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else
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printf("\n");
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}
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return 0;
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}
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