-/**
- * @file
- * huffman tree builder and VLC generator
+/*
* Copyright (c) 2006 Konstantin Shishkov
+ * Copyright (c) 2007 Loren Merritt
*
* This file is part of Libav.
*
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
+/**
+ * @file
+ * huffman tree builder and VLC generator
+ */
+
+#include <stdint.h>
+
#include "avcodec.h"
#include "get_bits.h"
#include "huffman.h"
/* symbol for Huffman tree node */
#define HNODE -1
+typedef struct HeapElem {
+ uint64_t val;
+ int name;
+} HeapElem;
+
+static void heap_sift(HeapElem *h, int root, int size)
+{
+ while (root * 2 + 1 < size) {
+ int child = root * 2 + 1;
+ if (child < size - 1 && h[child].val > h[child+1].val)
+ child++;
+ if (h[root].val > h[child].val) {
+ FFSWAP(HeapElem, h[root], h[child]);
+ root = child;
+ } else
+ break;
+ }
+}
+
+void ff_huff_gen_len_table(uint8_t *dst, const uint64_t *stats)
+{
+ HeapElem h[256];
+ int up[2*256];
+ int len[2*256];
+ int offset, i, next;
+ int size = 256;
+
+ for (offset = 1; ; offset <<= 1) {
+ for (i=0; i < size; i++) {
+ h[i].name = i;
+ h[i].val = (stats[i] << 8) + offset;
+ }
+ for (i = size / 2 - 1; i >= 0; i--)
+ heap_sift(h, i, size);
+
+ for (next = size; next < size * 2 - 1; next++) {
+ // merge the two smallest entries, and put it back in the heap
+ uint64_t min1v = h[0].val;
+ up[h[0].name] = next;
+ h[0].val = INT64_MAX;
+ heap_sift(h, 0, size);
+ up[h[0].name] = next;
+ h[0].name = next;
+ h[0].val += min1v;
+ heap_sift(h, 0, size);
+ }
+
+ len[2 * size - 2] = 0;
+ for (i = 2 * size - 3; i >= size; i--)
+ len[i] = len[up[i]] + 1;
+ for (i = 0; i < size; i++) {
+ dst[i] = len[up[i]] + 1;
+ if (dst[i] >= 32) break;
+ }
+ if (i==size) break;
+ }
+}
-static void get_tree_codes(uint32_t *bits, int16_t *lens, uint8_t *xlat, Node *nodes, int node, uint32_t pfx, int pl, int *pos, int no_zero_count)
+static void get_tree_codes(uint32_t *bits, int16_t *lens, uint8_t *xlat,
+ Node *nodes, int node,
+ uint32_t pfx, int pl, int *pos, int no_zero_count)
{
int s;
s = nodes[node].sym;
- if(s != HNODE || (no_zero_count && !nodes[node].count)){
+ if (s != HNODE || (no_zero_count && !nodes[node].count)) {
bits[*pos] = pfx;
lens[*pos] = pl;
xlat[*pos] = s;
(*pos)++;
- }else{
+ } else {
pfx <<= 1;
pl++;
- get_tree_codes(bits, lens, xlat, nodes, nodes[node].n0, pfx, pl, pos,
- no_zero_count);
+ get_tree_codes(bits, lens, xlat, nodes, nodes[node].n0, pfx, pl,
+ pos, no_zero_count);
pfx |= 1;
- get_tree_codes(bits, lens, xlat, nodes, nodes[node].n0+1, pfx, pl, pos,
- no_zero_count);
+ get_tree_codes(bits, lens, xlat, nodes, nodes[node].n0 + 1, pfx, pl,
+ pos, no_zero_count);
}
}
-static int build_huff_tree(VLC *vlc, Node *nodes, int head, int flags)
+static int build_huff_tree(VLC *vlc, Node *nodes, int head, int flags, int nb_bits)
{
int no_zero_count = !(flags & FF_HUFFMAN_FLAG_ZERO_COUNT);
uint32_t bits[256];
uint8_t xlat[256];
int pos = 0;
- get_tree_codes(bits, lens, xlat, nodes, head, 0, 0, &pos, no_zero_count);
- return init_vlc_sparse(vlc, 9, pos, lens, 2, 2, bits, 4, 4, xlat, 1, 1, 0);
+ get_tree_codes(bits, lens, xlat, nodes, head, 0, 0,
+ &pos, no_zero_count);
+ return ff_init_vlc_sparse(vlc, nb_bits, pos, lens, 2, 2, bits, 4, 4, xlat, 1, 1, 0);
}
* nodes size must be 2*nb_codes
* first nb_codes nodes.count must be set
*/
-int ff_huff_build_tree(AVCodecContext *avctx, VLC *vlc, int nb_codes,
+int ff_huff_build_tree(AVCodecContext *avctx, VLC *vlc, int nb_codes, int nb_bits,
Node *nodes, HuffCmp cmp, int flags)
{
int i, j;
int cur_node;
int64_t sum = 0;
- for(i = 0; i < nb_codes; i++){
+ for (i = 0; i < nb_codes; i++) {
nodes[i].sym = i;
nodes[i].n0 = -2;
sum += nodes[i].count;
}
- if(sum >> 31) {
- av_log(avctx, AV_LOG_ERROR, "Too high symbol frequencies. Tree construction is not possible\n");
+ if (sum >> 31) {
+ av_log(avctx, AV_LOG_ERROR,
+ "Too high symbol frequencies. "
+ "Tree construction is not possible\n");
return -1;
}
qsort(nodes, nb_codes, sizeof(Node), cmp);
cur_node = nb_codes;
nodes[nb_codes*2-1].count = 0;
- for(i = 0; i < nb_codes*2-1; i += 2){
+ for (i = 0; i < nb_codes * 2 - 1; i += 2) {
nodes[cur_node].sym = HNODE;
- nodes[cur_node].count = nodes[i].count + nodes[i+1].count;
+ nodes[cur_node].count = nodes[i].count + nodes[i + 1].count;
nodes[cur_node].n0 = i;
- for(j = cur_node; j > 0; j--){
- if(nodes[j].count > nodes[j-1].count ||
- (nodes[j].count == nodes[j-1].count &&
- (!(flags & FF_HUFFMAN_FLAG_HNODE_FIRST) ||
- nodes[j].n0==j-1 || nodes[j].n0==j-2 ||
- (nodes[j].sym!=HNODE && nodes[j-1].sym!=HNODE))))
+ for (j = cur_node; j > 0; j--) {
+ if (nodes[j].count > nodes[j - 1].count ||
+ (nodes[j].count == nodes[j - 1].count &&
+ (!(flags & FF_HUFFMAN_FLAG_HNODE_FIRST) ||
+ nodes[j].n0 == j - 1 || nodes[j].n0 == j - 2 ||
+ (nodes[j].sym!=HNODE && nodes[j-1].sym!=HNODE))))
break;
- FFSWAP(Node, nodes[j], nodes[j-1]);
+ FFSWAP(Node, nodes[j], nodes[j - 1]);
}
cur_node++;
}
- if(build_huff_tree(vlc, nodes, nb_codes*2-2, flags) < 0){
+ if (build_huff_tree(vlc, nodes, nb_codes * 2 - 2, flags, nb_bits) < 0) {
av_log(avctx, AV_LOG_ERROR, "Error building tree\n");
return -1;
}
projects / ffmpeg / blobdiff