Imported Debian version 2.5.3~trusty1
[deb_ffmpeg.git] / ffmpeg / libavcodec / huffman.c
CommitLineData
2ba45a60
DM
1/*
2 * Copyright (c) 2006 Konstantin Shishkov
3 * Copyright (c) 2007 Loren Merritt
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22/**
23 * @file
24 * huffman tree builder and VLC generator
25 */
26
27#include <stdint.h>
28
29#include "avcodec.h"
30#include "get_bits.h"
31#include "huffman.h"
32
33/* symbol for Huffman tree node */
34#define HNODE -1
35
36typedef struct {
37 uint64_t val;
38 int name;
39} HeapElem;
40
41static void heap_sift(HeapElem *h, int root, int size)
42{
43 while (root * 2 + 1 < size) {
44 int child = root * 2 + 1;
45 if (child < size - 1 && h[child].val > h[child+1].val)
46 child++;
47 if (h[root].val > h[child].val) {
48 FFSWAP(HeapElem, h[root], h[child]);
49 root = child;
50 } else
51 break;
52 }
53}
54
55int ff_huff_gen_len_table(uint8_t *dst, const uint64_t *stats, int stats_size, int skip0)
56{
57 HeapElem *h = av_malloc_array(sizeof(*h), stats_size);
58 int *up = av_malloc_array(sizeof(*up) * 2, stats_size);
59 uint8_t *len = av_malloc_array(sizeof(*len) * 2, stats_size);
60 uint16_t *map= av_malloc_array(sizeof(*map), stats_size);
61 int offset, i, next;
62 int size = 0;
63 int ret = 0;
64
65 if (!h || !up || !len) {
66 ret = AVERROR(ENOMEM);
67 goto end;
68 }
69
70 for (i = 0; i<stats_size; i++) {
71 dst[i] = 255;
72 if (stats[i] || !skip0)
73 map[size++] = i;
74 }
75
76 for (offset = 1; ; offset <<= 1) {
77 for (i=0; i < size; i++) {
78 h[i].name = i;
79 h[i].val = (stats[map[i]] << 14) + offset;
80 }
81 for (i = size / 2 - 1; i >= 0; i--)
82 heap_sift(h, i, size);
83
84 for (next = size; next < size * 2 - 1; next++) {
85 // merge the two smallest entries, and put it back in the heap
86 uint64_t min1v = h[0].val;
87 up[h[0].name] = next;
88 h[0].val = INT64_MAX;
89 heap_sift(h, 0, size);
90 up[h[0].name] = next;
91 h[0].name = next;
92 h[0].val += min1v;
93 heap_sift(h, 0, size);
94 }
95
96 len[2 * size - 2] = 0;
97 for (i = 2 * size - 3; i >= size; i--)
98 len[i] = len[up[i]] + 1;
99 for (i = 0; i < size; i++) {
100 dst[map[i]] = len[up[i]] + 1;
101 if (dst[map[i]] >= 32) break;
102 }
103 if (i==size) break;
104 }
105end:
106 av_free(h);
107 av_free(up);
108 av_free(len);
109 av_free(map);
110 return ret;
111}
112
113static void get_tree_codes(uint32_t *bits, int16_t *lens, uint8_t *xlat,
114 Node *nodes, int node,
115 uint32_t pfx, int pl, int *pos, int no_zero_count)
116{
117 int s;
118
119 s = nodes[node].sym;
120 if (s != HNODE || (no_zero_count && !nodes[node].count)) {
121 bits[*pos] = pfx;
122 lens[*pos] = pl;
123 xlat[*pos] = s;
124 (*pos)++;
125 } else {
126 pfx <<= 1;
127 pl++;
128 get_tree_codes(bits, lens, xlat, nodes, nodes[node].n0, pfx, pl,
129 pos, no_zero_count);
130 pfx |= 1;
131 get_tree_codes(bits, lens, xlat, nodes, nodes[node].n0 + 1, pfx, pl,
132 pos, no_zero_count);
133 }
134}
135
136static int build_huff_tree(VLC *vlc, Node *nodes, int head, int flags, int nb_bits)
137{
138 int no_zero_count = !(flags & FF_HUFFMAN_FLAG_ZERO_COUNT);
139 uint32_t bits[256];
140 int16_t lens[256];
141 uint8_t xlat[256];
142 int pos = 0;
143
144 get_tree_codes(bits, lens, xlat, nodes, head, 0, 0,
145 &pos, no_zero_count);
146 return ff_init_vlc_sparse(vlc, nb_bits, pos, lens, 2, 2, bits, 4, 4, xlat, 1, 1, 0);
147}
148
149
150/**
151 * nodes size must be 2*nb_codes
152 * first nb_codes nodes.count must be set
153 */
154int ff_huff_build_tree(AVCodecContext *avctx, VLC *vlc, int nb_codes, int nb_bits,
155 Node *nodes, HuffCmp cmp, int flags)
156{
157 int i, j;
158 int cur_node;
159 int64_t sum = 0;
160
161 for (i = 0; i < nb_codes; i++) {
162 nodes[i].sym = i;
163 nodes[i].n0 = -2;
164 sum += nodes[i].count;
165 }
166
167 if (sum >> 31) {
168 av_log(avctx, AV_LOG_ERROR,
169 "Too high symbol frequencies. "
170 "Tree construction is not possible\n");
171 return -1;
172 }
173 qsort(nodes, nb_codes, sizeof(Node), cmp);
174 cur_node = nb_codes;
175 nodes[nb_codes*2-1].count = 0;
176 for (i = 0; i < nb_codes * 2 - 1; i += 2) {
177 uint32_t cur_count = nodes[i].count + nodes[i+1].count;
178 // find correct place to insert new node, and
179 // make space for the new node while at it
180 for(j = cur_node; j > i + 2; j--){
181 if(cur_count > nodes[j-1].count ||
182 (cur_count == nodes[j-1].count &&
183 !(flags & FF_HUFFMAN_FLAG_HNODE_FIRST)))
184 break;
185 nodes[j] = nodes[j - 1];
186 }
187 nodes[j].sym = HNODE;
188 nodes[j].count = cur_count;
189 nodes[j].n0 = i;
190 cur_node++;
191 }
192 if (build_huff_tree(vlc, nodes, nb_codes * 2 - 2, flags, nb_bits) < 0) {
193 av_log(avctx, AV_LOG_ERROR, "Error building tree\n");
194 return -1;
195 }
196 return 0;
197}