--- /dev/null
+/*
+ * Copyright (C) 2007 Vitor <vitor1001@gmail.com>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file cbook_gen.c
+ * Codebook Generator using the ELBG algorithm
+ */
+
+#include <string.h>
+
+#include "elbg.h"
+#include "avcodec.h"
+#include "random.h"
+
+#define DELTA_ERR_MAX 0.1 ///< Precision of the ELBG algorithm (as percentual error)
+
+/**
+ * In the ELBG jargon, a cell is the set of points that are closest to a
+ * codebook entry. Not to be confused with a RoQ Video cell. */
+typedef struct cell_s {
+ int index;
+ struct cell_s *next;
+} cell;
+
+/**
+ * ELBG internal data
+ */
+typedef struct{
+ int error;
+ int dim;
+ int numCB;
+ int *codebook;
+ cell **cells;
+ int *utility;
+ int *utility_inc;
+ int *nearest_cb;
+ int *points;
+ AVRandomState *rand_state;
+} elbg_data;
+
+static inline int distance_limited(int *a, int *b, int dim, int limit)
+{
+ int i, dist=0;
+ for (i=0; i<dim; i++) {
+ dist += (a[i] - b[i])*(a[i] - b[i]);
+ if (dist > limit)
+ return INT_MAX;
+ }
+
+ return dist;
+}
+
+static inline void vect_division(int *res, int *vect, int div, int dim)
+{
+ int i;
+ if (div > 1)
+ for (i=0; i<dim; i++)
+ res[i] = ROUNDED_DIV(vect[i],div);
+ else if (res != vect)
+ memcpy(res, vect, dim*sizeof(int));
+
+}
+
+static int eval_error_cell(elbg_data *elbg, int *centroid, cell *cells)
+{
+ int error=0;
+ for (; cells; cells=cells->next)
+ error += distance_limited(centroid, elbg->points + cells->index*elbg->dim, elbg->dim, INT_MAX);
+
+ return error;
+}
+
+static int get_closest_codebook(elbg_data *elbg, int index)
+{
+ int i, pick=0, diff, diff_min = INT_MAX;
+ for (i=0; i<elbg->numCB; i++)
+ if (i != index) {
+ diff = distance_limited(elbg->codebook + i*elbg->dim, elbg->codebook + index*elbg->dim, elbg->dim, diff_min);
+ if (diff < diff_min) {
+ pick = i;
+ diff_min = diff;
+ }
+ }
+ return pick;
+}
+
+static int get_high_utility_cell(elbg_data *elbg)
+{
+ int i=0;
+ /* Using linear search, do binary if it ever turns to be speed critical */
+ int r = av_random(elbg->rand_state)%elbg->utility_inc[elbg->numCB-1];
+ while (elbg->utility_inc[i] < r)
+ i++;
+ return i;
+}
+
+/**
+ * Implementation of the simple LBG algorithm for just two codebooks
+ */
+static int simple_lbg(int dim,
+ int centroid[3][dim],
+ int newutility[3],
+ int *points,
+ cell *cells)
+{
+ int i, idx;
+ int numpoints[2] = {0,0};
+ int newcentroid[2][dim];
+ cell *tempcell;
+
+ memset(newcentroid, 0, sizeof(newcentroid));
+
+ newutility[0] =
+ newutility[1] = 0;
+
+ for (tempcell = cells; tempcell; tempcell=tempcell->next) {
+ idx = distance_limited(centroid[0], points + tempcell->index*dim, dim, INT_MAX)>=
+ distance_limited(centroid[1], points + tempcell->index*dim, dim, INT_MAX);
+ numpoints[idx]++;
+ for (i=0; i<dim; i++)
+ newcentroid[idx][i] += points[tempcell->index*dim + i];
+ }
+
+ vect_division(centroid[0], newcentroid[0], numpoints[0], dim);
+ vect_division(centroid[1], newcentroid[1], numpoints[1], dim);
+
+ for (tempcell = cells; tempcell; tempcell=tempcell->next) {
+ int dist[2] = {distance_limited(centroid[0], points + tempcell->index*dim, dim, INT_MAX),
+ distance_limited(centroid[1], points + tempcell->index*dim, dim, INT_MAX)};
+ int idx = dist[0] > dist[1];
+ newutility[idx] += dist[idx];
+ }
+
+ return newutility[0] + newutility[1];
+}
+
+static void get_new_centroids(elbg_data *elbg, int huc, int *newcentroid_i,
+ int *newcentroid_p)
+{
+ cell *tempcell;
+ int min[elbg->dim];
+ int max[elbg->dim];
+ int i;
+
+ for (i=0; i< elbg->dim; i++) {
+ min[i]=INT_MAX;
+ max[i]=0;
+ }
+
+ for (tempcell = elbg->cells[huc]; tempcell; tempcell = tempcell->next)
+ for(i=0; i<elbg->dim; i++) {
+ min[i]=FFMIN(min[i], elbg->points[tempcell->index*elbg->dim + i]);
+ max[i]=FFMAX(max[i], elbg->points[tempcell->index*elbg->dim + i]);
+ }
+
+ for (i=0; i<elbg->dim; i++) {
+ newcentroid_i[i] = min[i] + (max[i] - min[i])/3;
+ newcentroid_p[i] = min[i] + (2*(max[i] - min[i]))/3;
+ }
+}
+
+/**
+ * Add the points in the low utility cell to its closest cell. Split the high
+ * utility cell, putting the separed points in the (now empty) low utility
+ * cell.
+ *
+ * @param elbg Internal elbg data
+ * @param indexes {luc, huc, cluc}
+ * @param newcentroid A vector with the position of the new centroids
+ */
+static void shift_codebook(elbg_data *elbg, int *indexes,
+ int newcentroid[3][elbg->dim])
+{
+ cell *tempdata;
+ cell **pp = &elbg->cells[indexes[2]];
+
+ while(*pp)
+ pp= &(*pp)->next;
+
+ *pp = elbg->cells[indexes[0]];
+
+ elbg->cells[indexes[0]] = NULL;
+ tempdata = elbg->cells[indexes[1]];
+ elbg->cells[indexes[1]] = NULL;
+
+ while(tempdata) {
+ cell *tempcell2 = tempdata->next;
+ int idx = distance_limited(elbg->points + tempdata->index*elbg->dim,
+ newcentroid[0], elbg->dim, INT_MAX) >
+ distance_limited(elbg->points + tempdata->index*elbg->dim,
+ newcentroid[1], elbg->dim, INT_MAX);
+
+ tempdata->next = elbg->cells[indexes[idx]];
+ elbg->cells[indexes[idx]] = tempdata;
+ tempdata = tempcell2;
+ }
+}
+
+static void evaluate_utility_inc(elbg_data *elbg)
+{
+ int i, inc=0;
+
+ for (i=0; i < elbg->numCB; i++) {
+ if (elbg->numCB*elbg->utility[i] > elbg->error)
+ inc += elbg->utility[i];
+ elbg->utility_inc[i] = inc;
+ }
+}
+
+
+static void update_utility_and_n_cb(elbg_data *elbg, int idx, int newutility)
+{
+ cell *tempcell;
+
+ elbg->utility[idx] = newutility;
+ for (tempcell=elbg->cells[idx]; tempcell; tempcell=tempcell->next)
+ elbg->nearest_cb[tempcell->index] = idx;
+}
+
+/**
+ * Evaluate if a shift lower the error. If it does, call shift_codebooks
+ * and update elbg->error, elbg->utility and elbg->nearest_cb.
+ *
+ * @param elbg Internal elbg data
+ * @param indexes {luc (low utility cell, huc (high utility cell), cluc (closest cell to low utility cell)}
+ */
+static void try_shift_candidate(elbg_data *elbg, int idx[3])
+{
+ int j, k, olderror=0, newerror, cont=0;
+ int newutility[3];
+ int newcentroid[3][elbg->dim];
+ cell *tempcell;
+
+ for (j=0; j<3; j++)
+ olderror += elbg->utility[idx[j]];
+
+ memset(newcentroid[2], 0, elbg->dim*sizeof(int));
+
+ for (k=0; k<2; k++)
+ for (tempcell=elbg->cells[idx[2*k]]; tempcell; tempcell=tempcell->next) {
+ cont++;
+ for (j=0; j<elbg->dim; j++)
+ newcentroid[2][j] += elbg->points[tempcell->index*elbg->dim + j];
+ }
+
+ vect_division(newcentroid[2], newcentroid[2], cont, elbg->dim);
+
+ get_new_centroids(elbg, idx[1], newcentroid[0], newcentroid[1]);
+
+ newutility[2] = eval_error_cell(elbg, newcentroid[2], elbg->cells[idx[0]]);
+ newutility[2] += eval_error_cell(elbg, newcentroid[2], elbg->cells[idx[2]]);
+
+ newerror = newutility[2];
+
+ newerror += simple_lbg(elbg->dim, newcentroid, newutility, elbg->points,
+ elbg->cells[idx[1]]);
+
+ if (olderror > newerror) {
+ shift_codebook(elbg, idx, newcentroid);
+
+ elbg->error += newerror - olderror;
+
+ for (j=0; j<3; j++)
+ update_utility_and_n_cb(elbg, idx[j], newutility[j]);
+
+ evaluate_utility_inc(elbg);
+ }
+ }
+
+/**
+ * Implementation of the ELBG block
+ */
+static void do_shiftings(elbg_data *elbg)
+{
+ int idx[3];
+
+ evaluate_utility_inc(elbg);
+
+ for (idx[0]=0; idx[0] < elbg->numCB; idx[0]++)
+ if (elbg->numCB*elbg->utility[idx[0]] < elbg->error) {
+ if (elbg->utility_inc[elbg->numCB-1] == 0)
+ return;
+
+ idx[1] = get_high_utility_cell(elbg);
+ idx[2] = get_closest_codebook(elbg, idx[0]);
+
+ try_shift_candidate(elbg, idx);
+ }
+}
+
+#define BIG_PRIME 433494437LL
+
+void ff_init_elbg(int *points, int dim, int numpoints, int *codebook,
+ int numCB, int max_steps, int *closest_cb,
+ AVRandomState *rand_state)
+{
+ int i, k;
+
+ if (numpoints > 24*numCB) {
+ /* ELBG is very costly for a big number of points. So if we have a lot
+ of them, get a good initial codebook to save on iterations */
+ int *temp_points = av_malloc(dim*(numpoints/8)*sizeof(int));
+ for (i=0; i<numpoints/8; i++) {
+ k = (i*BIG_PRIME) % numpoints;
+ memcpy(temp_points + i*dim, points + k*dim, dim*sizeof(int));
+ }
+
+ ff_init_elbg(temp_points, dim, numpoints/8, codebook, numCB, 2*max_steps, closest_cb, rand_state);
+ ff_do_elbg(temp_points, dim, numpoints/8, codebook, numCB, 2*max_steps, closest_cb, rand_state);
+
+ av_free(temp_points);
+
+ } else // If not, initialize the codebook with random positions
+ for (i=0; i < numCB; i++)
+ memcpy(codebook + i*dim, points + ((i*BIG_PRIME)%numpoints)*dim,
+ dim*sizeof(int));
+
+}
+
+void ff_do_elbg(int *points, int dim, int numpoints, int *codebook,
+ int numCB, int max_steps, int *closest_cb,
+ AVRandomState *rand_state)
+{
+ int dist;
+ elbg_data elbg_d;
+ elbg_data *elbg = &elbg_d;
+ int i, j, k, last_error, steps=0;
+ int *dist_cb = av_malloc(numpoints*sizeof(int));
+ int *size_part = av_malloc(numCB*sizeof(int));
+ cell *list_buffer = av_malloc(numpoints*sizeof(cell));
+ cell *free_cells;
+
+ elbg->error = INT_MAX;
+ elbg->dim = dim;
+ elbg->numCB = numCB;
+ elbg->codebook = codebook;
+ elbg->cells = av_malloc(numCB*sizeof(cell *));
+ elbg->utility = av_malloc(numCB*sizeof(int));
+ elbg->nearest_cb = closest_cb;
+ elbg->points = points;
+ elbg->utility_inc = av_malloc(numCB*sizeof(int));
+
+ elbg->rand_state = rand_state;
+
+ do {
+ free_cells = list_buffer;
+ last_error = elbg->error;
+ steps++;
+ memset(elbg->utility, 0, numCB*sizeof(int));
+ memset(elbg->cells, 0, numCB*sizeof(cell *));
+
+ elbg->error = 0;
+
+ /* This loop evaluate the actual Voronoi partition. It is the most
+ costly part of the algorithm. */
+ for (i=0; i < numpoints; i++) {
+ dist_cb[i] = INT_MAX;
+ for (k=0; k < elbg->numCB; k++) {
+ dist = distance_limited(elbg->points + i*elbg->dim, elbg->codebook + k*elbg->dim, dim, dist_cb[i]);
+ if (dist < dist_cb[i]) {
+ dist_cb[i] = dist;
+ elbg->nearest_cb[i] = k;
+ }
+ }
+ elbg->error += dist_cb[i];
+ elbg->utility[elbg->nearest_cb[i]] += dist_cb[i];
+ free_cells->index = i;
+ free_cells->next = elbg->cells[elbg->nearest_cb[i]];
+ elbg->cells[elbg->nearest_cb[i]] = free_cells;
+ free_cells++;
+ }
+
+ do_shiftings(elbg);
+
+ memset(size_part, 0, numCB*sizeof(int));
+
+ memset(elbg->codebook, 0, elbg->numCB*dim*sizeof(int));
+
+ for (i=0; i < numpoints; i++) {
+ size_part[elbg->nearest_cb[i]]++;
+ for (j=0; j < elbg->dim; j++)
+ elbg->codebook[elbg->nearest_cb[i]*elbg->dim + j] +=
+ elbg->points[i*elbg->dim + j];
+ }
+
+ for (i=0; i < elbg->numCB; i++)
+ vect_division(elbg->codebook + i*elbg->dim,
+ elbg->codebook + i*elbg->dim, size_part[i], elbg->dim);
+
+ } while(((last_error - elbg->error) > DELTA_ERR_MAX*elbg->error) &&
+ (steps < max_steps));
+
+ av_free(dist_cb);
+ av_free(size_part);
+ av_free(elbg->utility);
+ av_free(list_buffer);
+ av_free(elbg->cells);
+ av_free(elbg->utility_inc);
+}