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/*
* Copyright (c) 2016, Alliance for Open Media. All rights reserved
*
* This source code is subject to the terms of the BSD 2 Clause License and
* the Alliance for Open Media Patent License 1.0. If the BSD 2 Clause License
* was not distributed with this source code in the LICENSE file, you can
* obtain it at www.aomedia.org/license/software. If the Alliance for Open
* Media Patent License 1.0 was not distributed with this source code in the
* PATENTS file, you can obtain it at www.aomedia.org/license/patent.
*/
#include <assert.h>
#include <stdint.h>
#include <string.h>
#include "av1/encoder/palette.h"
#include "av1/encoder/random.h"
#ifndef AV1_K_MEANS_DIM
#error "This template requires AV1_K_MEANS_DIM to be defined"
#endif
#define RENAME_(x, y) AV1_K_MEANS_RENAME(x, y)
#define RENAME(x) RENAME_(x, AV1_K_MEANS_DIM)
static float RENAME(calc_dist)(const float *p1, const float *p2) {
float dist = 0;
int i;
for (i = 0; i < AV1_K_MEANS_DIM; ++i) {
const float diff = p1[i] - p2[i];
dist += diff * diff;
}
return dist;
}
void RENAME(av1_calc_indices)(const float *data, const float *centroids,
uint8_t *indices, int n, int k) {
int i, j;
for (i = 0; i < n; ++i) {
float min_dist = RENAME(calc_dist)(data + i * AV1_K_MEANS_DIM, centroids);
indices[i] = 0;
for (j = 1; j < k; ++j) {
const float this_dist = RENAME(calc_dist)(
data + i * AV1_K_MEANS_DIM, centroids + j * AV1_K_MEANS_DIM);
if (this_dist < min_dist) {
min_dist = this_dist;
indices[i] = j;
}
}
}
}
static void RENAME(calc_centroids)(const float *data, float *centroids,
const uint8_t *indices, int n, int k) {
int i, j, index;
int count[PALETTE_MAX_SIZE];
unsigned int rand_state = (unsigned int)data[0];
assert(n <= 32768);
memset(count, 0, sizeof(count[0]) * k);
memset(centroids, 0, sizeof(centroids[0]) * k * AV1_K_MEANS_DIM);
for (i = 0; i < n; ++i) {
index = indices[i];
assert(index < k);
++count[index];
for (j = 0; j < AV1_K_MEANS_DIM; ++j) {
centroids[index * AV1_K_MEANS_DIM + j] += data[i * AV1_K_MEANS_DIM + j];
}
}
for (i = 0; i < k; ++i) {
if (count[i] == 0) {
memcpy(centroids + i * AV1_K_MEANS_DIM,
data + (lcg_rand16(&rand_state) % n) * AV1_K_MEANS_DIM,
sizeof(centroids[0]) * AV1_K_MEANS_DIM);
} else {
const float norm = 1.0f / count[i];
for (j = 0; j < AV1_K_MEANS_DIM; ++j)
centroids[i * AV1_K_MEANS_DIM + j] *= norm;
}
}
// Round to nearest integers.
for (i = 0; i < k * AV1_K_MEANS_DIM; ++i) {
centroids[i] = roundf(centroids[i]);
}
}
static float RENAME(calc_total_dist)(const float *data, const float *centroids,
const uint8_t *indices, int n, int k) {
float dist = 0;
int i;
(void)k;
for (i = 0; i < n; ++i)
dist += RENAME(calc_dist)(data + i * AV1_K_MEANS_DIM,
centroids + indices[i] * AV1_K_MEANS_DIM);
return dist;
}
void RENAME(av1_k_means)(const float *data, float *centroids, uint8_t *indices,
int n, int k, int max_itr) {
int i;
float this_dist;
float pre_centroids[2 * PALETTE_MAX_SIZE];
uint8_t pre_indices[MAX_SB_SQUARE];
RENAME(av1_calc_indices)(data, centroids, indices, n, k);
this_dist = RENAME(calc_total_dist)(data, centroids, indices, n, k);
for (i = 0; i < max_itr; ++i) {
const float pre_dist = this_dist;
memcpy(pre_centroids, centroids,
sizeof(pre_centroids[0]) * k * AV1_K_MEANS_DIM);
memcpy(pre_indices, indices, sizeof(pre_indices[0]) * n);
RENAME(calc_centroids)(data, centroids, indices, n, k);
RENAME(av1_calc_indices)(data, centroids, indices, n, k);
this_dist = RENAME(calc_total_dist)(data, centroids, indices, n, k);
if (this_dist > pre_dist) {
memcpy(centroids, pre_centroids,
sizeof(pre_centroids[0]) * k * AV1_K_MEANS_DIM);
memcpy(indices, pre_indices, sizeof(pre_indices[0]) * n);
break;
}
if (!memcmp(centroids, pre_centroids,
sizeof(pre_centroids[0]) * k * AV1_K_MEANS_DIM))
break;
}
}
#undef RENAME_
#undef RENAME
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