FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavcodec/huffman.c
Date: 2025-04-25 22:50:00
Exec Total Coverage
Lines: 88 94 93.6%
Functions: 5 5 100.0%
Branches: 92 102 90.2%
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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 "libavutil/error.h"
30 #include "libavutil/log.h"
31 #include "libavutil/macros.h"
32 #include "libavutil/mem.h"
33 #include "libavutil/qsort.h"
34
35 #include "huffman.h"
36 #include "vlc.h"
37
38 /* symbol for Huffman tree node */
39 #define HNODE -1
40
41 typedef struct HeapElem {
42 uint64_t val;
43 int name;
44 } HeapElem;
45
46 1973140 static void heap_sift(HeapElem *h, int root, int size)
47 {
48
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 14116069 while (root * 2 + 1 < size) {
49 13354908 int child = root * 2 + 1;
50
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 13354908 if (child < size - 1 && h[child].val > h[child+1].val)
51 6177070 child++;
52
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 13354908 if (h[root].val > h[child].val) {
53 12142929 FFSWAP(HeapElem, h[root], h[child]);
54 12142929 root = child;
55 } else
56 1211979 break;
57 }
58 1973140 }
59
60 2446 int ff_huff_gen_len_table(uint8_t *dst, const uint64_t *stats, int stats_size, int skip0)
61 {
62 2446 HeapElem *h = av_malloc_array(sizeof(*h), stats_size);
63 2446 int *up = av_malloc_array(sizeof(*up) * 2, stats_size);
64 2446 uint8_t *len = av_malloc_array(sizeof(*len) * 2, stats_size);
65 2446 uint16_t *map= av_malloc_array(sizeof(*map), stats_size);
66 int offset, i, next;
67 2446 int size = 0;
68 2446 int ret = 0;
69
70
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 2446 if (!h || !up || !len || !map) {
71 ✗ ret = AVERROR(ENOMEM);
72 ✗ goto end;
73 }
74
75
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 877454 for (i = 0; i<stats_size; i++) {
76 875008 dst[i] = 255;
77
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 875008 if (stats[i] || !skip0)
78 791317 map[size++] = i;
79 }
80
81 2446 for (offset = 1; ; offset <<= 1) {
82
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 793763 for (i=0; i < size; i++) {
83 791317 h[i].name = i;
84 791317 h[i].val = (stats[map[i]] << 14) + offset;
85 }
86
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 397844 for (i = size / 2 - 1; i >= 0; i--)
87 395398 heap_sift(h, i, size);
88
89
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 791317 for (next = size; next < size * 2 - 1; next++) {
90 // merge the two smallest entries, and put it back in the heap
91 788871 uint64_t min1v = h[0].val;
92 788871 up[h[0].name] = next;
93 788871 h[0].val = INT64_MAX;
94 788871 heap_sift(h, 0, size);
95 788871 up[h[0].name] = next;
96 788871 h[0].name = next;
97 788871 h[0].val += min1v;
98 788871 heap_sift(h, 0, size);
99 }
100
101 2446 len[2 * size - 2] = 0;
102
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 788871 for (i = 2 * size - 3; i >= size; i--)
103 786425 len[i] = len[up[i]] + 1;
104
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 793763 for (i = 0; i < size; i++) {
105 791317 dst[map[i]] = len[up[i]] + 1;
106
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 791317 if (dst[map[i]] >= 32) break;
107 }
108
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 2446 if (i==size) break;
109 }
110 2446 end:
111 2446 av_free(h);
112 2446 av_free(up);
113 2446 av_free(len);
114 2446 av_free(map);
115 2446 return ret;
116 }
117
118 287031 static void get_tree_codes(int8_t *lens, uint8_t *xlat,
119 Node *nodes, int node, int pl, int *pos, int no_zero_count)
120 {
121 int s;
122
123 287031 s = nodes[node].sym;
124
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 287031 if (s != HNODE || (no_zero_count && !nodes[node].count)) {
125 145362 lens[*pos] = pl;
126 145362 xlat[*pos] = s;
127 145362 (*pos)++;
128 } else {
129 141669 pl++;
130 141669 get_tree_codes(lens, xlat, nodes, nodes[node].n0, pl,
131 pos, no_zero_count);
132 141669 get_tree_codes(lens, xlat, nodes, nodes[node].n0 + 1, pl,
133 pos, no_zero_count);
134 }
135 287031 }
136
137 3693 static int build_huff_tree(VLC *vlc, Node *nodes, int head, int flags, int nb_bits, void *logctx)
138 {
139 3693 int no_zero_count = !(flags & FF_HUFFMAN_FLAG_ZERO_COUNT);
140 int8_t lens[256];
141 uint8_t xlat[256];
142 3693 int pos = 0;
143
144 3693 get_tree_codes(lens, xlat, nodes, head, 0,
145 &pos, no_zero_count);
146 3693 return ff_vlc_init_from_lengths(vlc, nb_bits, pos, lens, 1,
147 xlat, 1, 1, 0, 0, logctx);
148 }
149
150
151 /**
152 * nodes size must be 2*nb_codes
153 * first nb_codes nodes.count must be set
154 */
155 3693 int ff_huff_build_tree(void *logctx, VLC *vlc, int nb_codes, int nb_bits,
156 Node *nodes, HuffCmp cmp, int flags)
157 {
158 int i, j;
159 int cur_node;
160 3693 int64_t sum = 0;
161
162
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 149055 for (i = 0; i < nb_codes; i++) {
163 145362 nodes[i].sym = i;
164 145362 nodes[i].n0 = -2;
165 145362 sum += nodes[i].count;
166 }
167
168
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 3693 if (sum >> 31) {
169 ✗ av_log(logctx, AV_LOG_ERROR,
170 "Too high symbol frequencies. "
171 "Tree construction is not possible\n");
172 ✗ return -1;
173 }
174
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 864150 AV_QSORT(nodes, nb_codes, Node, cmp);
175 3693 cur_node = nb_codes;
176 3693 nodes[nb_codes*2-1].count = 0;
177
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 149055 for (i = 0; i < nb_codes * 2 - 1; i += 2) {
178 145362 uint32_t cur_count = nodes[i].count + nodes[i+1].count;
179 // find correct place to insert new node, and
180 // make space for the new node while at it
181
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 5639871 for(j = cur_node; j > i + 2; j--){
182
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 5623698 if(cur_count > nodes[j-1].count ||
183
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 5565907 (cur_count == nodes[j-1].count &&
184
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 90183 !(flags & FF_HUFFMAN_FLAG_HNODE_FIRST)))
185 break;
186 5494509 nodes[j] = nodes[j - 1];
187 }
188 145362 nodes[j].sym = HNODE;
189 145362 nodes[j].count = cur_count;
190 145362 nodes[j].n0 = i;
191 145362 cur_node++;
192 }
193
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 3693 if (build_huff_tree(vlc, nodes, nb_codes * 2 - 2, flags, nb_bits, logctx) < 0) {
194 ✗ av_log(logctx, AV_LOG_ERROR, "Error building tree\n");
195 ✗ return -1;
196 }
197 3693 return 0;
198 }
199