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00026 #include <string.h>
00027
00028 #include "elbg.h"
00029 #include "avcodec.h"
00030 #include "random.h"
00031
00032 #define DELTA_ERR_MAX 0.1
00033
00034
00037 typedef struct cell_s {
00038 int index;
00039 struct cell_s *next;
00040 } cell;
00041
00045 typedef struct{
00046 int error;
00047 int dim;
00048 int numCB;
00049 int *codebook;
00050 cell **cells;
00051 int *utility;
00052 int *utility_inc;
00053 int *nearest_cb;
00054 int *points;
00055 AVRandomState *rand_state;
00056 } elbg_data;
00057
00058 static inline int distance_limited(int *a, int *b, int dim, int limit)
00059 {
00060 int i, dist=0;
00061 for (i=0; i<dim; i++) {
00062 dist += (a[i] - b[i])*(a[i] - b[i]);
00063 if (dist > limit)
00064 return INT_MAX;
00065 }
00066
00067 return dist;
00068 }
00069
00070 static inline void vect_division(int *res, int *vect, int div, int dim)
00071 {
00072 int i;
00073 if (div > 1)
00074 for (i=0; i<dim; i++)
00075 res[i] = ROUNDED_DIV(vect[i],div);
00076 else if (res != vect)
00077 memcpy(res, vect, dim*sizeof(int));
00078
00079 }
00080
00081 static int eval_error_cell(elbg_data *elbg, int *centroid, cell *cells)
00082 {
00083 int error=0;
00084 for (; cells; cells=cells->next)
00085 error += distance_limited(centroid, elbg->points + cells->index*elbg->dim, elbg->dim, INT_MAX);
00086
00087 return error;
00088 }
00089
00090 static int get_closest_codebook(elbg_data *elbg, int index)
00091 {
00092 int i, pick=0, diff, diff_min = INT_MAX;
00093 for (i=0; i<elbg->numCB; i++)
00094 if (i != index) {
00095 diff = distance_limited(elbg->codebook + i*elbg->dim, elbg->codebook + index*elbg->dim, elbg->dim, diff_min);
00096 if (diff < diff_min) {
00097 pick = i;
00098 diff_min = diff;
00099 }
00100 }
00101 return pick;
00102 }
00103
00104 static int get_high_utility_cell(elbg_data *elbg)
00105 {
00106 int i=0;
00107
00108 int r = av_random(elbg->rand_state)%elbg->utility_inc[elbg->numCB-1];
00109 while (elbg->utility_inc[i] < r)
00110 i++;
00111 return i;
00112 }
00113
00117 static int simple_lbg(int dim,
00118 int *centroid[3],
00119 int newutility[3],
00120 int *points,
00121 cell *cells)
00122 {
00123 int i, idx;
00124 int numpoints[2] = {0,0};
00125 int newcentroid[2][dim];
00126 cell *tempcell;
00127
00128 memset(newcentroid, 0, sizeof(newcentroid));
00129
00130 newutility[0] =
00131 newutility[1] = 0;
00132
00133 for (tempcell = cells; tempcell; tempcell=tempcell->next) {
00134 idx = distance_limited(centroid[0], points + tempcell->index*dim, dim, INT_MAX)>=
00135 distance_limited(centroid[1], points + tempcell->index*dim, dim, INT_MAX);
00136 numpoints[idx]++;
00137 for (i=0; i<dim; i++)
00138 newcentroid[idx][i] += points[tempcell->index*dim + i];
00139 }
00140
00141 vect_division(centroid[0], newcentroid[0], numpoints[0], dim);
00142 vect_division(centroid[1], newcentroid[1], numpoints[1], dim);
00143
00144 for (tempcell = cells; tempcell; tempcell=tempcell->next) {
00145 int dist[2] = {distance_limited(centroid[0], points + tempcell->index*dim, dim, INT_MAX),
00146 distance_limited(centroid[1], points + tempcell->index*dim, dim, INT_MAX)};
00147 int idx = dist[0] > dist[1];
00148 newutility[idx] += dist[idx];
00149 }
00150
00151 return newutility[0] + newutility[1];
00152 }
00153
00154 static void get_new_centroids(elbg_data *elbg, int huc, int *newcentroid_i,
00155 int *newcentroid_p)
00156 {
00157 cell *tempcell;
00158 int min[elbg->dim];
00159 int max[elbg->dim];
00160 int i;
00161
00162 for (i=0; i< elbg->dim; i++) {
00163 min[i]=INT_MAX;
00164 max[i]=0;
00165 }
00166
00167 for (tempcell = elbg->cells[huc]; tempcell; tempcell = tempcell->next)
00168 for(i=0; i<elbg->dim; i++) {
00169 min[i]=FFMIN(min[i], elbg->points[tempcell->index*elbg->dim + i]);
00170 max[i]=FFMAX(max[i], elbg->points[tempcell->index*elbg->dim + i]);
00171 }
00172
00173 for (i=0; i<elbg->dim; i++) {
00174 newcentroid_i[i] = min[i] + (max[i] - min[i])/3;
00175 newcentroid_p[i] = min[i] + (2*(max[i] - min[i]))/3;
00176 }
00177 }
00178
00188 static void shift_codebook(elbg_data *elbg, int *indexes,
00189 int *newcentroid[3])
00190 {
00191 cell *tempdata;
00192 cell **pp = &elbg->cells[indexes[2]];
00193
00194 while(*pp)
00195 pp= &(*pp)->next;
00196
00197 *pp = elbg->cells[indexes[0]];
00198
00199 elbg->cells[indexes[0]] = NULL;
00200 tempdata = elbg->cells[indexes[1]];
00201 elbg->cells[indexes[1]] = NULL;
00202
00203 while(tempdata) {
00204 cell *tempcell2 = tempdata->next;
00205 int idx = distance_limited(elbg->points + tempdata->index*elbg->dim,
00206 newcentroid[0], elbg->dim, INT_MAX) >
00207 distance_limited(elbg->points + tempdata->index*elbg->dim,
00208 newcentroid[1], elbg->dim, INT_MAX);
00209
00210 tempdata->next = elbg->cells[indexes[idx]];
00211 elbg->cells[indexes[idx]] = tempdata;
00212 tempdata = tempcell2;
00213 }
00214 }
00215
00216 static void evaluate_utility_inc(elbg_data *elbg)
00217 {
00218 int i, inc=0;
00219
00220 for (i=0; i < elbg->numCB; i++) {
00221 if (elbg->numCB*elbg->utility[i] > elbg->error)
00222 inc += elbg->utility[i];
00223 elbg->utility_inc[i] = inc;
00224 }
00225 }
00226
00227
00228 static void update_utility_and_n_cb(elbg_data *elbg, int idx, int newutility)
00229 {
00230 cell *tempcell;
00231
00232 elbg->utility[idx] = newutility;
00233 for (tempcell=elbg->cells[idx]; tempcell; tempcell=tempcell->next)
00234 elbg->nearest_cb[tempcell->index] = idx;
00235 }
00236
00244 static void try_shift_candidate(elbg_data *elbg, int idx[3])
00245 {
00246 int j, k, olderror=0, newerror, cont=0;
00247 int newutility[3];
00248 int newcentroid[3][elbg->dim];
00249 int *newcentroid_ptrs[3] = { newcentroid[0], newcentroid[1], newcentroid[2] };
00250 cell *tempcell;
00251
00252 for (j=0; j<3; j++)
00253 olderror += elbg->utility[idx[j]];
00254
00255 memset(newcentroid[2], 0, elbg->dim*sizeof(int));
00256
00257 for (k=0; k<2; k++)
00258 for (tempcell=elbg->cells[idx[2*k]]; tempcell; tempcell=tempcell->next) {
00259 cont++;
00260 for (j=0; j<elbg->dim; j++)
00261 newcentroid[2][j] += elbg->points[tempcell->index*elbg->dim + j];
00262 }
00263
00264 vect_division(newcentroid[2], newcentroid[2], cont, elbg->dim);
00265
00266 get_new_centroids(elbg, idx[1], newcentroid[0], newcentroid[1]);
00267
00268 newutility[2] = eval_error_cell(elbg, newcentroid[2], elbg->cells[idx[0]]);
00269 newutility[2] += eval_error_cell(elbg, newcentroid[2], elbg->cells[idx[2]]);
00270
00271 newerror = newutility[2];
00272
00273 newerror += simple_lbg(elbg->dim, newcentroid_ptrs, newutility, elbg->points,
00274 elbg->cells[idx[1]]);
00275
00276 if (olderror > newerror) {
00277 shift_codebook(elbg, idx, newcentroid_ptrs);
00278
00279 elbg->error += newerror - olderror;
00280
00281 for (j=0; j<3; j++)
00282 update_utility_and_n_cb(elbg, idx[j], newutility[j]);
00283
00284 evaluate_utility_inc(elbg);
00285 }
00286 }
00287
00291 static void do_shiftings(elbg_data *elbg)
00292 {
00293 int idx[3];
00294
00295 evaluate_utility_inc(elbg);
00296
00297 for (idx[0]=0; idx[0] < elbg->numCB; idx[0]++)
00298 if (elbg->numCB*elbg->utility[idx[0]] < elbg->error) {
00299 if (elbg->utility_inc[elbg->numCB-1] == 0)
00300 return;
00301
00302 idx[1] = get_high_utility_cell(elbg);
00303 idx[2] = get_closest_codebook(elbg, idx[0]);
00304
00305 try_shift_candidate(elbg, idx);
00306 }
00307 }
00308
00309 #define BIG_PRIME 433494437LL
00310
00311 void ff_init_elbg(int *points, int dim, int numpoints, int *codebook,
00312 int numCB, int max_steps, int *closest_cb,
00313 AVRandomState *rand_state)
00314 {
00315 int i, k;
00316
00317 if (numpoints > 24*numCB) {
00318
00319
00320 int *temp_points = av_malloc(dim*(numpoints/8)*sizeof(int));
00321 for (i=0; i<numpoints/8; i++) {
00322 k = (i*BIG_PRIME) % numpoints;
00323 memcpy(temp_points + i*dim, points + k*dim, dim*sizeof(int));
00324 }
00325
00326 ff_init_elbg(temp_points, dim, numpoints/8, codebook, numCB, 2*max_steps, closest_cb, rand_state);
00327 ff_do_elbg(temp_points, dim, numpoints/8, codebook, numCB, 2*max_steps, closest_cb, rand_state);
00328
00329 av_free(temp_points);
00330
00331 } else
00332 for (i=0; i < numCB; i++)
00333 memcpy(codebook + i*dim, points + ((i*BIG_PRIME)%numpoints)*dim,
00334 dim*sizeof(int));
00335
00336 }
00337
00338 void ff_do_elbg(int *points, int dim, int numpoints, int *codebook,
00339 int numCB, int max_steps, int *closest_cb,
00340 AVRandomState *rand_state)
00341 {
00342 int dist;
00343 elbg_data elbg_d;
00344 elbg_data *elbg = &elbg_d;
00345 int i, j, k, last_error, steps=0;
00346 int *dist_cb = av_malloc(numpoints*sizeof(int));
00347 int *size_part = av_malloc(numCB*sizeof(int));
00348 cell *list_buffer = av_malloc(numpoints*sizeof(cell));
00349 cell *free_cells;
00350
00351 elbg->error = INT_MAX;
00352 elbg->dim = dim;
00353 elbg->numCB = numCB;
00354 elbg->codebook = codebook;
00355 elbg->cells = av_malloc(numCB*sizeof(cell *));
00356 elbg->utility = av_malloc(numCB*sizeof(int));
00357 elbg->nearest_cb = closest_cb;
00358 elbg->points = points;
00359 elbg->utility_inc = av_malloc(numCB*sizeof(int));
00360
00361 elbg->rand_state = rand_state;
00362
00363 do {
00364 free_cells = list_buffer;
00365 last_error = elbg->error;
00366 steps++;
00367 memset(elbg->utility, 0, numCB*sizeof(int));
00368 memset(elbg->cells, 0, numCB*sizeof(cell *));
00369
00370 elbg->error = 0;
00371
00372
00373
00374 for (i=0; i < numpoints; i++) {
00375 dist_cb[i] = INT_MAX;
00376 for (k=0; k < elbg->numCB; k++) {
00377 dist = distance_limited(elbg->points + i*elbg->dim, elbg->codebook + k*elbg->dim, dim, dist_cb[i]);
00378 if (dist < dist_cb[i]) {
00379 dist_cb[i] = dist;
00380 elbg->nearest_cb[i] = k;
00381 }
00382 }
00383 elbg->error += dist_cb[i];
00384 elbg->utility[elbg->nearest_cb[i]] += dist_cb[i];
00385 free_cells->index = i;
00386 free_cells->next = elbg->cells[elbg->nearest_cb[i]];
00387 elbg->cells[elbg->nearest_cb[i]] = free_cells;
00388 free_cells++;
00389 }
00390
00391 do_shiftings(elbg);
00392
00393 memset(size_part, 0, numCB*sizeof(int));
00394
00395 memset(elbg->codebook, 0, elbg->numCB*dim*sizeof(int));
00396
00397 for (i=0; i < numpoints; i++) {
00398 size_part[elbg->nearest_cb[i]]++;
00399 for (j=0; j < elbg->dim; j++)
00400 elbg->codebook[elbg->nearest_cb[i]*elbg->dim + j] +=
00401 elbg->points[i*elbg->dim + j];
00402 }
00403
00404 for (i=0; i < elbg->numCB; i++)
00405 vect_division(elbg->codebook + i*elbg->dim,
00406 elbg->codebook + i*elbg->dim, size_part[i], elbg->dim);
00407
00408 } while(((last_error - elbg->error) > DELTA_ERR_MAX*elbg->error) &&
00409 (steps < max_steps));
00410
00411 av_free(dist_cb);
00412 av_free(size_part);
00413 av_free(elbg->utility);
00414 av_free(list_buffer);
00415 av_free(elbg->cells);
00416 av_free(elbg->utility_inc);
00417 }