#include <vector>
#include <algorithm>
+#include "audioreader.h"
#include "interpolate.h"
+#include "tap.h"
#define BUFSIZE 4096
#define HYSTERESIS_LIMIT 3000
-#define SAMPLE_RATE 44100
#define C64_FREQUENCY 985248
-#define TAP_RESOLUTION 8
#define SYNC_PULSE_START 1000
-#define SYNC_PULSE_END 15000
+#define SYNC_PULSE_END 20000
#define SYNC_PULSE_LENGTH 378.0
#define SYNC_TEST_TOLERANCE 1.10
-struct tap_header {
- char identifier[12];
- char version;
- char reserved[3];
- unsigned int data_len;
-};
-
// between [x,x+1]
double find_zerocrossing(const std::vector<short> &pcm, int x)
{
double time; // in seconds from start
double len; // in seconds
};
+
+// Calibrate on the first ~25k pulses (skip a few, just to be sure).
+double calibrate(const std::vector<pulse> &pulses) {
+ if (pulses.size() < SYNC_PULSE_END) {
+ fprintf(stderr, "Too few pulses, not calibrating!\n");
+ return 1.0;
+ }
+
+ int sync_pulse_end = -1;
+ double sync_pulse_stddev = -1.0;
+
+ // Compute the standard deviation (to check for uneven speeds).
+ // If it suddenly skyrockets, we assume that sync ended earlier
+ // than we thought (it should be 25000 cycles), and that we should
+ // calibrate on fewer cycles.
+ for (int try_end : { 2000, 4000, 5000, 7500, 10000, 15000, SYNC_PULSE_END }) {
+ double sum2 = 0.0;
+ for (int i = SYNC_PULSE_START; i < try_end; ++i) {
+ double cycles = pulses[i].len * C64_FREQUENCY;
+ sum2 += (cycles - SYNC_PULSE_LENGTH) * (cycles - SYNC_PULSE_LENGTH);
+ }
+ double stddev = sqrt(sum2 / (try_end - SYNC_PULSE_START - 1));
+ if (sync_pulse_end != -1 && stddev > 5.0 && stddev / sync_pulse_stddev > 1.3) {
+ fprintf(stderr, "Stopping at %d sync pulses because standard deviation would be too big (%.2f cycles); shorter-than-usual trailer?\n",
+ sync_pulse_end, stddev);
+ break;
+ }
+ sync_pulse_end = try_end;
+ sync_pulse_stddev = stddev;
+ }
+ fprintf(stderr, "Sync pulse length standard deviation: %.2f cycles\n",
+ sync_pulse_stddev);
+
+ double sum = 0.0;
+ for (int i = SYNC_PULSE_START; i < sync_pulse_end; ++i) {
+ sum += pulses[i].len;
+ }
+ double mean_length = C64_FREQUENCY * sum / (sync_pulse_end - SYNC_PULSE_START);
+ double calibration_factor = SYNC_PULSE_LENGTH / mean_length;
+ 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) {
+ double cycles = pulses[i].len * calibration_factor * C64_FREQUENCY;
+ if (cycles < SYNC_PULSE_LENGTH / SYNC_TEST_TOLERANCE || cycles > SYNC_PULSE_LENGTH * SYNC_TEST_TOLERANCE) {
+ fprintf(stderr, "Sync cycle with downflank at %.6f was detected at %.0f cycles; misdetect?\n",
+ pulses[i].time, cycles);
+ }
+ }
+
+ return calibration_factor;
+}
int main(int argc, char **argv)
{
make_lanczos_weight_table();
std::vector<short> pcm;
-
- while (!feof(stdin)) {
- short buf[BUFSIZE];
- ssize_t ret = fread(buf, 2, BUFSIZE, stdin);
- if (ret >= 0) {
- pcm.insert(pcm.end(), buf, buf + ret);
- }
- }
+ int sample_rate;
+ if (!read_audio_file(argv[1], &pcm, &sample_rate)) {
+ exit(1);
+ }
#if 0
for (int i = 0; i < LEN; ++i) {
if (!true_pulse) {
#if 0
fprintf(stderr, "Ignored down-flank at %.6f seconds due to hysteresis (%d < %d).\n",
- double(i) / SAMPLE_RATE, -min_level_after, HYSTERESIS_LIMIT);
+ double(i) / sample_rate, -min_level_after, HYSTERESIS_LIMIT);
#endif
i = j;
continue;
}
// down-flank!
- double t = find_zerocrossing(pcm, i - 1) * (1.0 / SAMPLE_RATE);
+ double t = find_zerocrossing(pcm, i - 1) * (1.0 / sample_rate);
if (last_downflank > 0) {
pulse p;
p.time = t;
last_bit = bit;
}
- // Calibrate on the first ~25k pulses (skip a few, just to be sure).
- double calibration_factor = 1.0f;
- if (pulses.size() < SYNC_PULSE_END) {
- fprintf(stderr, "Too few pulses, not calibrating!\n");
- } else {
- double sum = 0.0;
- for (int i = SYNC_PULSE_START; i < SYNC_PULSE_END; ++i) {
- sum += pulses[i].len;
- }
- 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 -> %.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) {
- double cycles = pulses[i].len * calibration_factor * C64_FREQUENCY;
- if (cycles < SYNC_PULSE_LENGTH / SYNC_TEST_TOLERANCE || cycles > SYNC_PULSE_LENGTH * SYNC_TEST_TOLERANCE) {
- fprintf(stderr, "Sync cycle with downflank at %.6f was detected at %.0f cycles; misdetect?\n",
- pulses[i].time, cycles);
- }
- }
-
- // Compute the standard deviation (to check for uneven speeds).
- double sum2 = 0.0;
- for (int i = SYNC_PULSE_START; i < SYNC_PULSE_END; ++i) {
- double cycles = pulses[i].len * calibration_factor * C64_FREQUENCY;
- sum2 += (cycles - SYNC_PULSE_LENGTH) * (cycles - SYNC_PULSE_LENGTH);
- }
- double stddev = sqrt(sum2 / (SYNC_PULSE_END - SYNC_PULSE_START - 1));
- fprintf(stderr, "Sync pulse length standard deviation: %.2f cycles\n",
- stddev);
- }
+ double calibration_factor = calibrate(pulses);
FILE *fp = fopen("cycles.plot", "w");
std::vector<char> tap_data;
short zero = 0;
unsigned pulsenum = 0;
for (unsigned i = 0; i < pcm.size(); ++i) {
- unsigned next_pulse = (pulsenum >= pulses.size()) ? INT_MAX : int(pulses[pulsenum].time * SAMPLE_RATE);
+ unsigned next_pulse = (pulsenum >= pulses.size()) ? INT_MAX : int(pulses[pulsenum].time * sample_rate);
if (i >= next_pulse) {
fwrite(&one, sizeof(one), 1, fp);
++pulsenum;
projects / c64tapwav / blobdiff