git.sesse.net Git - c64tapwav/blob - sync.cpp

   1 // A program that tries to sync up the two channels, using Viterbi decoding
   2 // to find the most likely misalignment as it changes throughout the file.
   3
   4 #define NUM_THEORIES 200
   5 #define THEORY_FROM -10.0  /* in samples */
   6 #define THEORY_TO 10.0  /* in samples */
   7 #define SWITCH_COST 1000.0  /* pretty arbitrary */
   8
   9 #include <stdio.h>
  10 #include <math.h>
  11 #include <vector>
  12 #include <algorithm>
  13
  14 #include "interpolate.h"
  15
  16 #define BUFSIZE 4096
  17
  18 struct stereo_sample {
  19         short left, right;
  20 };
  21 struct double_stereo_sample {
  22         double left, right;
  23 };
  24
  25 inline short clip(int x)
  26 {
  27         if (x < -32768) {
  28                 return x;
  29         } else if (x > 32767) {
  30                 return 32767;
  31         } else {
  32                 return short(x);
  33         }
  34 }
  35
  36 struct hypothesis {
  37         int id;
  38         double cost;
  39         hypothesis *prev;
  40 };
  41
  42 int main(int argc, char **argv)
  43 {
  44         std::vector<stereo_sample> pcm;
  45
  46         while (!feof(stdin)) {
  47                 stereo_sample buf[BUFSIZE];
  48                 ssize_t ret = fread(buf, sizeof(stereo_sample), BUFSIZE, stdin);
  49                 if (ret >= 0) {
  50                         pcm.insert(pcm.end(), buf, buf + ret);
  51                 }
  52         }
  53
  54         double sum_left = 0.0, sum_right = 0.0;
  55         for (unsigned i = 0; i < pcm.size(); ++i) {
  56                 sum_left += pcm[i].left;
  57                 sum_right += pcm[i].right;
  58         }
  59         double mean_left = sum_left / pcm.size();
  60         double mean_right = sum_right / pcm.size();
  61
  62         //fprintf(stderr, "Mean: L=%f R=%f\n", mean_left, mean_right);
  63
  64         double sum2_left = 0.0, sum2_right = 0.0;
  65         for (unsigned i = 0; i < pcm.size(); ++i) {
  66                 sum2_left += (pcm[i].left - mean_left) * (pcm[i].left - mean_left);
  67                 sum2_right += (pcm[i].right - mean_right) * (pcm[i].right - mean_right);
  68         }
  69         double var_left = sum2_left / (pcm.size() - 1);
  70         double var_right = sum2_right / (pcm.size() - 1);
  71
  72         //fprintf(stderr, "Stddev: L=%f R=%f\n", sqrt(var_left), sqrt(var_right));
  73
  74         double inv_sd_left = 1.0 / sqrt(var_left);
  75         double inv_sd_right = 1.0 / sqrt(var_right);
  76
  77         std::vector<double_stereo_sample> norm;
  78         norm.resize(pcm.size());
  79
  80         for (unsigned i = 0; i < pcm.size(); ++i) {
  81                 norm[i].left = (pcm[i].left - mean_left) * inv_sd_left;
  82                 norm[i].right = (pcm[i].right - mean_right) * inv_sd_right;
  83         }
  84
  85 #if 0
  86         double offset = 0.0;
  87         double old_diff = 0.0;
  88         for (unsigned i = 0; i < pcm.size(); ++i) {
  89                 double left = (pcm[i].left - mean_left) * inv_sd_left;
  90                 double right = (interpolate(pcm, i + offset) - mean_right) * inv_sd_right;
  91
  92                 double diff = right - left;
  93                 old_diff = old_diff * 0.9999 + diff * 0.0001;
  94                 offset -= 0.1 * old_diff;
  95
  96                 if (i % 100 == 0) {
  97                         fprintf(stderr, "%7.3f: %7.3f [diff=%8.3f lagged diff=%8.3f]\n", i / 44100.0, offset, diff, old_diff);
  98                 }
  99                 printf("%f %f %f\n", i / 44100.0, left, right);
 100         }
 101 #endif
 102
 103         double delays[NUM_THEORIES];
 104         hypothesis *bases = new hypothesis[NUM_THEORIES];
 105
 106         for (int h = 0; h < NUM_THEORIES; ++h) {
 107                 delays[h] = THEORY_FROM + h * (THEORY_TO - THEORY_FROM) / (NUM_THEORIES - 1);
 108                 bases[h].id = h;
 109                 bases[h].cost = 0.0;
 110                 bases[h].prev = NULL;
 111         }
 112
 113         fprintf(stderr, "Matching blocks... %7.2f", 0.0);
 114         hypothesis *prev_hyp = bases;
 115         size_t total_end = pcm.size();
 116         //size_t total_end = 4410000;
 117         for (unsigned i = 0; i < total_end; i += BUFSIZE) {
 118                 fprintf(stderr, "\b\b\b\b\b\b\b%7.2f", i / 44100.0);
 119                 size_t end = std::min<size_t>(i + BUFSIZE, total_end);
 120
 121                 hypothesis *hyp = new hypothesis[NUM_THEORIES];
 122
 123                 // evaluate all hypotheses
 124                 for (int h = 0; h < NUM_THEORIES; ++h) {
 125                         double sum = 0.0;
 126                         double d = delays[h];
 127                         for (unsigned s = i; s < end; ++s) {
 128                                 double left = norm[s].left;
 129                                 double right = linear_interpolate_right(norm, s + d);
 130                                 double diff = (right - left) * (right - left);
 131                                 sum += diff;
 132                         }
 133
 134                         double best_cost = HUGE_VAL;
 135                         hypothesis *best_prev = NULL;
 136                         for (int hp = 0; hp < NUM_THEORIES; ++hp) {
 137                                 double switch_cost = SWITCH_COST * fabs(delays[hp] - delays[h]);
 138                                 double cost = prev_hyp[hp].cost + sum + switch_cost;
 139                                 if (best_prev == NULL || cost < best_cost) {
 140                                         best_cost = cost;
 141                                         best_prev = &prev_hyp[hp];
 142                                 }
 143                         }
 144
 145                         hyp[h].id = h;
 146                         hyp[h].cost = best_cost;
 147                         hyp[h].prev = best_prev;
 148                 }
 149
 150                 prev_hyp = hyp;
 151         }
 152         fprintf(stderr, "\b\b\b\b\b\b\b%7.2f\n", total_end / 44100.0);
 153
 154         // best winner
 155         double best_cost = HUGE_VAL;
 156         hypothesis *best_hyp = NULL;
 157         for (int h = 0; h < NUM_THEORIES; ++h) {
 158                 if (best_hyp == NULL || prev_hyp[h].cost < best_cost) {
 159                         best_cost = prev_hyp[h].cost;
 160                         best_hyp = &prev_hyp[h];
 161                 }
 162         }
 163
 164         // trace the path backwards
 165         std::vector<double> best_path;
 166         while (best_hyp != NULL) {
 167                 best_path.push_back(delays[best_hyp->id]);
 168                 best_hyp = best_hyp->prev;
 169         }
 170
 171         reverse(best_path.begin(), best_path.end());
 172
 173         fprintf(stderr, "Writing misalignment graphs to misalignment.plot...\n");
 174         FILE *fp = fopen("misalignment.plot", "w");
 175         for (unsigned i = 0; i < best_path.size(); ++i) {
 176                 fprintf(fp, "%f %f\n", i * BUFSIZE / 44100.0, best_path[i]);
 177         }
 178         fclose(fp);
 179
 180         fprintf(stderr, "Stretching right channel to match left... %7.2f%%", 0.0);
 181         double inv_sd = sqrt(2.0) / sqrt(var_left + var_right);
 182         std::vector<stereo_sample> aligned_pcm;
 183         std::vector<short> mono_pcm;
 184         for (unsigned i = 0; i < total_end; ++i) {
 185                 double d = linear_interpolate(best_path, i / double(BUFSIZE));
 186                 int left = pcm[i].left;
 187                 int right = linear_interpolate_right(pcm, i + d);
 188
 189                 stereo_sample ss;
 190                 ss.left = left;
 191                 ss.right = clip(right);
 192                 aligned_pcm.push_back(ss);
 193
 194                 mono_pcm.push_back(clip(lrintf(inv_sd * 4096.0 * (left + right))));
 195
 196                 if (i % 4096 == 0) {
 197                         fprintf(stderr, "\b\b\b\b\b\b\b\b%7.2f%%", 100.0 * i / total_end);
 198                 }
 199         }
 200         fprintf(stderr, "\b\b\b\b\b\b\b%7.2f%%\n", 100.0);
 201
 202         fprintf(stderr, "Writing realigned stereo channels to aligned.raw...\n");
 203         fp = fopen("aligned.raw", "wb");
 204         fwrite(aligned_pcm.data(), sizeof(stereo_sample) * aligned_pcm.size(), 1, fp);
 205         fclose(fp);
 206
 207         fprintf(stderr, "Writing combined mono track to combined.raw...\n");
 208         fp = fopen("combined.raw", "wb");
 209         fwrite(mono_pcm.data(), sizeof(short) * mono_pcm.size(), 1, fp);
 210         fclose(fp);
 211
 212         fprintf(stderr, "All done.\n");
 213
 214 #if 0
 215
 216         for (int sec = 0; sec < 2400; ++sec) {
 217                 double from_offset = -128.0;
 218                 double to_offset = 128.0;
 219                 double best_offset = HUGE_VAL;
 220                 for (int iter = 0; iter < 5; ++iter) {
 221                         //printf("from %f to %f\n", from_offset, to_offset);
 222                         double best_sum = HUGE_VAL;
 223
 224                         for (int k = 0; k < 100; ++k) {
 225                                 double offset = from_offset + k * 0.01 * (to_offset - from_offset);
 226                                 double sum = 0.0;
 227                                 for (unsigned i = sec * 4410; i < sec * 4410 + 4410; ++i) {
 228                                 //for (unsigned i = 100000; i < 10NUM_THEORIES0; ++i) {
 229                                         double left = norm[i].left;
 230                                         double right = interpolate(norm, i + offset);
 231                                         //double right = (norm[i + offset].right - mean_right) * inv_sd_right;
 232                                         double diff = (right - left) * (right - left);
 233                                         sum += diff;
 234                                 }
 235
 236                                 if (sum < best_sum) {
 237                                         best_sum = sum;
 238                                         best_offset = offset;
 239                                 }
 240
 241                                 //printf("%f %f\n", offset, sqrt(sum / NUM_THEORIES00.0f));
 242                                 //fflush(stdout);
 243                         }
 244
 245                         double range = 0.1 * (to_offset - from_offset);
 246                         from_offset = best_offset - range;
 247                         to_offset = best_offset + range;
 248                 }
 249                 printf("%d %f\n", sec, best_offset);
 250                 fflush(stdout);
 251         }
 252 #endif
 253
 254
 255 }