134 lines
3.9 KiB
C
134 lines
3.9 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 "../libcompandor/compandor.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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#define ATTACK_MS 15.0
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#define RECOVERY_MS 15.0
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static double test_frequency[3] = { 2000.0, 4000.0, 1000.0 };
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static sample_t samples_4db[SAMPLERATE];
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static sample_t samples_16db[SAMPLERATE];
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static sample_t samples_2db[SAMPLERATE];
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static sample_t samples_8db[SAMPLERATE];
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static sample_t samples_0db[SAMPLERATE];
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/* generate 2 samples: one with -4 dB, the other with -16 dB */
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static void generate_test_sample(double test_frequency)
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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 * test_frequency / (double)SAMPLERATE * i);
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samples_4db[i] = value * db2level(-4);
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samples_16db[i] = value * db2level(-16);
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samples_2db[i] = value * db2level(-2);
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samples_8db[i] = value * db2level(-8);
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samples_0db[i] = value;
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}
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}
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static void check_level(sample_t *samples, double duration, const char *desc, double target_db)
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{
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int i;
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double last = 0.0, envelop = 0.0;
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int up = 0;
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double factor;
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int when = (int)((double)SAMPLERATE + (double)SAMPLERATE * duration / 1000.0 + 0.5);
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//printf("%d %d\n", SAMPLERATE, when);
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for (i = 0; i < when; i++) {
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//puts(debug_amplitude(samples[i]));
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if (last < samples[i]) {
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up = 1;
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} else if (last > samples[i]) {
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if (up) {
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envelop = last;
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}
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up = 0;
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}
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#if 0
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if (i >= (SAMPLERATE-(SAMPLERATE/100)) && (i % (SAMPLERATE/(SAMPLERATE/10))) == 0)
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printf("%s: envelop = %.4f (val=%.4f) (when=%d)\n", desc, level2db(envelop), envelop, i);
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#endif
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last = samples[i];
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}
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factor = envelop / db2level(target_db);
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printf("%s: envelop after the instance of %.1f ms is %.4f db factor =%.4f\n", desc, duration, level2db(envelop), factor);
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}
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int main(void)
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{
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compandor_t cstate;
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sample_t samples[SAMPLERATE * 2];
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int f;
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init_compandor(&cstate, SAMPLERATE, ATTACK_MS, RECOVERY_MS);
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for (f = 0; f < 3; f++) {
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/* -16 and -4 dB */
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printf("Testing frequency %.0f Hz:\n", test_frequency[f]);
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generate_test_sample(test_frequency[f]);
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#if 0
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check_level(samples_0db, -100.0, "generate sample with 0db", 0.0);
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check_level(samples_2db, -100.0, "generate sample with -2db", -2.0);
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check_level(samples_4db, -100.0, "generate sample with -4db", -4.0);
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check_level(samples_8db, -100.0, "generate sample with -8db", -8.0);
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check_level(samples_16db, -100.0, "generate sample with -16db", -16.0);
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#endif
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/* low to high transition */
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memcpy(samples, samples_16db, SAMPLERATE * sizeof(sample_t));
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memcpy(samples + SAMPLERATE, samples_4db, SAMPLERATE * sizeof(sample_t));
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compress_audio(&cstate, samples, SAMPLERATE * 2);
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check_level(samples, ATTACK_MS, "compressor attack", -2.0);
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/* high to low transition */
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memcpy(samples, samples_4db, SAMPLERATE * sizeof(sample_t));
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memcpy(samples + SAMPLERATE, samples_16db, SAMPLERATE * sizeof(sample_t));
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compress_audio(&cstate, samples, SAMPLERATE * 2);
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check_level(samples, RECOVERY_MS, "compressor recovery", -8.0);
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/* low to high transition */
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memcpy(samples, samples_8db, SAMPLERATE * sizeof(sample_t));
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memcpy(samples + SAMPLERATE, samples_2db, SAMPLERATE * sizeof(sample_t));
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expand_audio(&cstate, samples, SAMPLERATE * 2);
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check_level(samples, ATTACK_MS, "expander attack", -4.0);
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/* high to low transition */
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memcpy(samples, samples_2db, SAMPLERATE * sizeof(sample_t));
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memcpy(samples + SAMPLERATE, samples_8db, SAMPLERATE * sizeof(sample_t));
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expand_audio(&cstate, samples, SAMPLERATE * 2);
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check_level(samples, RECOVERY_MS, "expander recovery", -16.0);
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/* 0 DB */
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memcpy(samples, samples_0db, SAMPLERATE * sizeof(sample_t));
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memcpy(samples + SAMPLERATE, samples_0db, SAMPLERATE * sizeof(sample_t));
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check_level(samples, RECOVERY_MS, "unaffected level", 0.0);
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puts("");
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}
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return 0;
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}
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