Imported Debian version 2.5.3~trusty1
[deb_ffmpeg.git] / ffmpeg / libavcodec / elbg.c
1 /*
2 * Copyright (C) 2007 Vitor Sessak <vitor1001@gmail.com>
3 *
4 * This file is part of FFmpeg.
5 *
6 * FFmpeg is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
10 *
11 * FFmpeg is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
15 *
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with FFmpeg; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20
21 /**
22 * @file
23 * Codebook Generator using the ELBG algorithm
24 */
25
26 #include <string.h>
27
28 #include "libavutil/avassert.h"
29 #include "libavutil/common.h"
30 #include "libavutil/lfg.h"
31 #include "elbg.h"
32 #include "avcodec.h"
33
34 #define DELTA_ERR_MAX 0.1 ///< Precision of the ELBG algorithm (as percentual error)
35
36 /**
37 * In the ELBG jargon, a cell is the set of points that are closest to a
38 * codebook entry. Not to be confused with a RoQ Video cell. */
39 typedef struct cell_s {
40 int index;
41 struct cell_s *next;
42 } cell;
43
44 /**
45 * ELBG internal data
46 */
47 typedef struct{
48 int error;
49 int dim;
50 int numCB;
51 int *codebook;
52 cell **cells;
53 int *utility;
54 int64_t *utility_inc;
55 int *nearest_cb;
56 int *points;
57 AVLFG *rand_state;
58 int *scratchbuf;
59 } elbg_data;
60
61 static inline int distance_limited(int *a, int *b, int dim, int limit)
62 {
63 int i, dist=0;
64 for (i=0; i<dim; i++) {
65 dist += (a[i] - b[i])*(a[i] - b[i]);
66 if (dist > limit)
67 return INT_MAX;
68 }
69
70 return dist;
71 }
72
73 static inline void vect_division(int *res, int *vect, int div, int dim)
74 {
75 int i;
76 if (div > 1)
77 for (i=0; i<dim; i++)
78 res[i] = ROUNDED_DIV(vect[i],div);
79 else if (res != vect)
80 memcpy(res, vect, dim*sizeof(int));
81
82 }
83
84 static int eval_error_cell(elbg_data *elbg, int *centroid, cell *cells)
85 {
86 int error=0;
87 for (; cells; cells=cells->next)
88 error += distance_limited(centroid, elbg->points + cells->index*elbg->dim, elbg->dim, INT_MAX);
89
90 return error;
91 }
92
93 static int get_closest_codebook(elbg_data *elbg, int index)
94 {
95 int i, pick=0, diff, diff_min = INT_MAX;
96 for (i=0; i<elbg->numCB; i++)
97 if (i != index) {
98 diff = distance_limited(elbg->codebook + i*elbg->dim, elbg->codebook + index*elbg->dim, elbg->dim, diff_min);
99 if (diff < diff_min) {
100 pick = i;
101 diff_min = diff;
102 }
103 }
104 return pick;
105 }
106
107 static int get_high_utility_cell(elbg_data *elbg)
108 {
109 int i=0;
110 /* Using linear search, do binary if it ever turns to be speed critical */
111 uint64_t r;
112
113 if (elbg->utility_inc[elbg->numCB-1] < INT_MAX) {
114 r = av_lfg_get(elbg->rand_state) % (unsigned int)elbg->utility_inc[elbg->numCB-1] + 1;
115 } else {
116 r = av_lfg_get(elbg->rand_state);
117 r = (av_lfg_get(elbg->rand_state) + (r<<32)) % elbg->utility_inc[elbg->numCB-1] + 1;
118 }
119
120 while (elbg->utility_inc[i] < r) {
121 i++;
122 }
123
124 av_assert2(elbg->cells[i]);
125
126 return i;
127 }
128
129 /**
130 * Implementation of the simple LBG algorithm for just two codebooks
131 */
132 static int simple_lbg(elbg_data *elbg,
133 int dim,
134 int *centroid[3],
135 int newutility[3],
136 int *points,
137 cell *cells)
138 {
139 int i, idx;
140 int numpoints[2] = {0,0};
141 int *newcentroid[2] = {
142 elbg->scratchbuf + 3*dim,
143 elbg->scratchbuf + 4*dim
144 };
145 cell *tempcell;
146
147 memset(newcentroid[0], 0, 2 * dim * sizeof(*newcentroid[0]));
148
149 newutility[0] =
150 newutility[1] = 0;
151
152 for (tempcell = cells; tempcell; tempcell=tempcell->next) {
153 idx = distance_limited(centroid[0], points + tempcell->index*dim, dim, INT_MAX)>=
154 distance_limited(centroid[1], points + tempcell->index*dim, dim, INT_MAX);
155 numpoints[idx]++;
156 for (i=0; i<dim; i++)
157 newcentroid[idx][i] += points[tempcell->index*dim + i];
158 }
159
160 vect_division(centroid[0], newcentroid[0], numpoints[0], dim);
161 vect_division(centroid[1], newcentroid[1], numpoints[1], dim);
162
163 for (tempcell = cells; tempcell; tempcell=tempcell->next) {
164 int dist[2] = {distance_limited(centroid[0], points + tempcell->index*dim, dim, INT_MAX),
165 distance_limited(centroid[1], points + tempcell->index*dim, dim, INT_MAX)};
166 int idx = dist[0] > dist[1];
167 newutility[idx] += dist[idx];
168 }
169
170 return newutility[0] + newutility[1];
171 }
172
173 static void get_new_centroids(elbg_data *elbg, int huc, int *newcentroid_i,
174 int *newcentroid_p)
175 {
176 cell *tempcell;
177 int *min = newcentroid_i;
178 int *max = newcentroid_p;
179 int i;
180
181 for (i=0; i< elbg->dim; i++) {
182 min[i]=INT_MAX;
183 max[i]=0;
184 }
185
186 for (tempcell = elbg->cells[huc]; tempcell; tempcell = tempcell->next)
187 for(i=0; i<elbg->dim; i++) {
188 min[i]=FFMIN(min[i], elbg->points[tempcell->index*elbg->dim + i]);
189 max[i]=FFMAX(max[i], elbg->points[tempcell->index*elbg->dim + i]);
190 }
191
192 for (i=0; i<elbg->dim; i++) {
193 int ni = min[i] + (max[i] - min[i])/3;
194 int np = min[i] + (2*(max[i] - min[i]))/3;
195 newcentroid_i[i] = ni;
196 newcentroid_p[i] = np;
197 }
198 }
199
200 /**
201 * Add the points in the low utility cell to its closest cell. Split the high
202 * utility cell, putting the separate points in the (now empty) low utility
203 * cell.
204 *
205 * @param elbg Internal elbg data
206 * @param indexes {luc, huc, cluc}
207 * @param newcentroid A vector with the position of the new centroids
208 */
209 static void shift_codebook(elbg_data *elbg, int *indexes,
210 int *newcentroid[3])
211 {
212 cell *tempdata;
213 cell **pp = &elbg->cells[indexes[2]];
214
215 while(*pp)
216 pp= &(*pp)->next;
217
218 *pp = elbg->cells[indexes[0]];
219
220 elbg->cells[indexes[0]] = NULL;
221 tempdata = elbg->cells[indexes[1]];
222 elbg->cells[indexes[1]] = NULL;
223
224 while(tempdata) {
225 cell *tempcell2 = tempdata->next;
226 int idx = distance_limited(elbg->points + tempdata->index*elbg->dim,
227 newcentroid[0], elbg->dim, INT_MAX) >
228 distance_limited(elbg->points + tempdata->index*elbg->dim,
229 newcentroid[1], elbg->dim, INT_MAX);
230
231 tempdata->next = elbg->cells[indexes[idx]];
232 elbg->cells[indexes[idx]] = tempdata;
233 tempdata = tempcell2;
234 }
235 }
236
237 static void evaluate_utility_inc(elbg_data *elbg)
238 {
239 int i;
240 int64_t inc=0;
241
242 for (i=0; i < elbg->numCB; i++) {
243 if (elbg->numCB*elbg->utility[i] > elbg->error)
244 inc += elbg->utility[i];
245 elbg->utility_inc[i] = inc;
246 }
247 }
248
249
250 static void update_utility_and_n_cb(elbg_data *elbg, int idx, int newutility)
251 {
252 cell *tempcell;
253
254 elbg->utility[idx] = newutility;
255 for (tempcell=elbg->cells[idx]; tempcell; tempcell=tempcell->next)
256 elbg->nearest_cb[tempcell->index] = idx;
257 }
258
259 /**
260 * Evaluate if a shift lower the error. If it does, call shift_codebooks
261 * and update elbg->error, elbg->utility and elbg->nearest_cb.
262 *
263 * @param elbg Internal elbg data
264 * @param idx {luc (low utility cell, huc (high utility cell), cluc (closest cell to low utility cell)}
265 */
266 static void try_shift_candidate(elbg_data *elbg, int idx[3])
267 {
268 int j, k, olderror=0, newerror, cont=0;
269 int newutility[3];
270 int *newcentroid[3] = {
271 elbg->scratchbuf,
272 elbg->scratchbuf + elbg->dim,
273 elbg->scratchbuf + 2*elbg->dim
274 };
275 cell *tempcell;
276
277 for (j=0; j<3; j++)
278 olderror += elbg->utility[idx[j]];
279
280 memset(newcentroid[2], 0, elbg->dim*sizeof(int));
281
282 for (k=0; k<2; k++)
283 for (tempcell=elbg->cells[idx[2*k]]; tempcell; tempcell=tempcell->next) {
284 cont++;
285 for (j=0; j<elbg->dim; j++)
286 newcentroid[2][j] += elbg->points[tempcell->index*elbg->dim + j];
287 }
288
289 vect_division(newcentroid[2], newcentroid[2], cont, elbg->dim);
290
291 get_new_centroids(elbg, idx[1], newcentroid[0], newcentroid[1]);
292
293 newutility[2] = eval_error_cell(elbg, newcentroid[2], elbg->cells[idx[0]]);
294 newutility[2] += eval_error_cell(elbg, newcentroid[2], elbg->cells[idx[2]]);
295
296 newerror = newutility[2];
297
298 newerror += simple_lbg(elbg, elbg->dim, newcentroid, newutility, elbg->points,
299 elbg->cells[idx[1]]);
300
301 if (olderror > newerror) {
302 shift_codebook(elbg, idx, newcentroid);
303
304 elbg->error += newerror - olderror;
305
306 for (j=0; j<3; j++)
307 update_utility_and_n_cb(elbg, idx[j], newutility[j]);
308
309 evaluate_utility_inc(elbg);
310 }
311 }
312
313 /**
314 * Implementation of the ELBG block
315 */
316 static void do_shiftings(elbg_data *elbg)
317 {
318 int idx[3];
319
320 evaluate_utility_inc(elbg);
321
322 for (idx[0]=0; idx[0] < elbg->numCB; idx[0]++)
323 if (elbg->numCB*elbg->utility[idx[0]] < elbg->error) {
324 if (elbg->utility_inc[elbg->numCB-1] == 0)
325 return;
326
327 idx[1] = get_high_utility_cell(elbg);
328 idx[2] = get_closest_codebook(elbg, idx[0]);
329
330 if (idx[1] != idx[0] && idx[1] != idx[2])
331 try_shift_candidate(elbg, idx);
332 }
333 }
334
335 #define BIG_PRIME 433494437LL
336
337 void avpriv_init_elbg(int *points, int dim, int numpoints, int *codebook,
338 int numCB, int max_steps, int *closest_cb,
339 AVLFG *rand_state)
340 {
341 int i, k;
342
343 if (numpoints > 24*numCB) {
344 /* ELBG is very costly for a big number of points. So if we have a lot
345 of them, get a good initial codebook to save on iterations */
346 int *temp_points = av_malloc_array(dim, (numpoints/8)*sizeof(int));
347 for (i=0; i<numpoints/8; i++) {
348 k = (i*BIG_PRIME) % numpoints;
349 memcpy(temp_points + i*dim, points + k*dim, dim*sizeof(int));
350 }
351
352 avpriv_init_elbg(temp_points, dim, numpoints/8, codebook, numCB, 2*max_steps, closest_cb, rand_state);
353 avpriv_do_elbg(temp_points, dim, numpoints/8, codebook, numCB, 2*max_steps, closest_cb, rand_state);
354
355 av_free(temp_points);
356
357 } else // If not, initialize the codebook with random positions
358 for (i=0; i < numCB; i++)
359 memcpy(codebook + i*dim, points + ((i*BIG_PRIME)%numpoints)*dim,
360 dim*sizeof(int));
361
362 }
363
364 void avpriv_do_elbg(int *points, int dim, int numpoints, int *codebook,
365 int numCB, int max_steps, int *closest_cb,
366 AVLFG *rand_state)
367 {
368 int dist;
369 elbg_data elbg_d;
370 elbg_data *elbg = &elbg_d;
371 int i, j, k, last_error, steps=0;
372 int *dist_cb = av_malloc_array(numpoints, sizeof(int));
373 int *size_part = av_malloc_array(numCB, sizeof(int));
374 cell *list_buffer = av_malloc_array(numpoints, sizeof(cell));
375 cell *free_cells;
376 int best_dist, best_idx = 0;
377
378 elbg->error = INT_MAX;
379 elbg->dim = dim;
380 elbg->numCB = numCB;
381 elbg->codebook = codebook;
382 elbg->cells = av_malloc_array(numCB, sizeof(cell *));
383 elbg->utility = av_malloc_array(numCB, sizeof(int));
384 elbg->nearest_cb = closest_cb;
385 elbg->points = points;
386 elbg->utility_inc = av_malloc_array(numCB, sizeof(*elbg->utility_inc));
387 elbg->scratchbuf = av_malloc_array(5*dim, sizeof(int));
388
389 elbg->rand_state = rand_state;
390
391 do {
392 free_cells = list_buffer;
393 last_error = elbg->error;
394 steps++;
395 memset(elbg->utility, 0, numCB*sizeof(int));
396 memset(elbg->cells, 0, numCB*sizeof(cell *));
397
398 elbg->error = 0;
399
400 /* This loop evaluate the actual Voronoi partition. It is the most
401 costly part of the algorithm. */
402 for (i=0; i < numpoints; i++) {
403 best_dist = distance_limited(elbg->points + i*elbg->dim, elbg->codebook + best_idx*elbg->dim, dim, INT_MAX);
404 for (k=0; k < elbg->numCB; k++) {
405 dist = distance_limited(elbg->points + i*elbg->dim, elbg->codebook + k*elbg->dim, dim, best_dist);
406 if (dist < best_dist) {
407 best_dist = dist;
408 best_idx = k;
409 }
410 }
411 elbg->nearest_cb[i] = best_idx;
412 dist_cb[i] = best_dist;
413 elbg->error += dist_cb[i];
414 elbg->utility[elbg->nearest_cb[i]] += dist_cb[i];
415 free_cells->index = i;
416 free_cells->next = elbg->cells[elbg->nearest_cb[i]];
417 elbg->cells[elbg->nearest_cb[i]] = free_cells;
418 free_cells++;
419 }
420
421 do_shiftings(elbg);
422
423 memset(size_part, 0, numCB*sizeof(int));
424
425 memset(elbg->codebook, 0, elbg->numCB*dim*sizeof(int));
426
427 for (i=0; i < numpoints; i++) {
428 size_part[elbg->nearest_cb[i]]++;
429 for (j=0; j < elbg->dim; j++)
430 elbg->codebook[elbg->nearest_cb[i]*elbg->dim + j] +=
431 elbg->points[i*elbg->dim + j];
432 }
433
434 for (i=0; i < elbg->numCB; i++)
435 vect_division(elbg->codebook + i*elbg->dim,
436 elbg->codebook + i*elbg->dim, size_part[i], elbg->dim);
437
438 } while(((last_error - elbg->error) > DELTA_ERR_MAX*elbg->error) &&
439 (steps < max_steps));
440
441 av_free(dist_cb);
442 av_free(size_part);
443 av_free(elbg->utility);
444 av_free(list_buffer);
445 av_free(elbg->cells);
446 av_free(elbg->utility_inc);
447 av_free(elbg->scratchbuf);
448 }