#define SYNC_PULSE_START 1000
#define SYNC_PULSE_END 15000
-#define SYNC_PULSE_LENGTH 380.0
+#define SYNC_PULSE_LENGTH 378.0
#define SYNC_TEST_TOLERANCE 1.10
struct tap_header {
// Find the flanks.
int last_bit = -1;
double last_upflank = -1;
- int last_max_level = 0;
for (unsigned i = 0; i < pcm.size(); ++i) {
int bit = (pcm[i] > 0) ? 1 : 0;
- if (bit == 1 && last_bit == 0 && last_max_level > HYSTERESIS_LIMIT) {
+ if (bit == 1 && last_bit == 0) {
+ // Check if we ever go up above HYSTERESIS_LIMIT before we dip down again.
+ bool true_pulse = false;
+ unsigned j;
+ int max_level_after = -32768;
+ for (j = i; j < pcm.size(); ++j) {
+ max_level_after = std::max<int>(max_level_after, pcm[j]);
+ if (pcm[j] < 0) break;
+ if (pcm[j] > HYSTERESIS_LIMIT) {
+ true_pulse = true;
+ break;
+ }
+ }
+
+ if (!true_pulse) {
+#if 0
+ fprintf(stderr, "Ignored up-flank at %.6f seconds due to hysteresis (%d < %d).\n",
+ double(i) / SAMPLE_RATE, max_level_after, HYSTERESIS_LIMIT);
+#endif
+ i = j;
+ continue;
+ }
+
// up-flank!
double t = find_zerocrossing(pcm, i - 1) * (1.0 / SAMPLE_RATE);
if (last_upflank > 0) {
pulses.push_back(p);
}
last_upflank = t;
- last_max_level = 0;
}
- last_max_level = std::max(last_max_level, abs(pcm[i]));
last_bit = bit;
}
}
double mean_length = C64_FREQUENCY * sum / (SYNC_PULSE_END - SYNC_PULSE_START);
calibration_factor = SYNC_PULSE_LENGTH / mean_length;
- fprintf(stderr, "Calibrated sync pulse length: %.2f -> 380.0 (change %+.2f%%)\n",
- mean_length, 100.0 * (calibration_factor - 1.0));
+ fprintf(stderr, "Calibrated sync pulse length: %.2f -> %.2f (change %+.2f%%)\n",
+ mean_length, SYNC_PULSE_LENGTH, 100.0 * (calibration_factor - 1.0));
// Check for pulses outside +/- 10% (sign of misdetection).
for (int i = SYNC_PULSE_START; i < SYNC_PULSE_END; ++i) {