mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2024-11-26 19:01:44 +02:00
113 lines
3.4 KiB
C
113 lines
3.4 KiB
C
/*
|
|
* Copyright (c) 2006 Konstantin Shishkov
|
|
*
|
|
* This file is part of Libav.
|
|
*
|
|
* Libav 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.
|
|
*
|
|
* Libav 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 Libav; if not, write to the Free Software
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
|
|
*/
|
|
|
|
/**
|
|
* @file
|
|
* huffman tree builder and VLC generator
|
|
*/
|
|
|
|
#include "avcodec.h"
|
|
#include "get_bits.h"
|
|
#include "huffman.h"
|
|
|
|
/* symbol for Huffman tree node */
|
|
#define HNODE -1
|
|
|
|
|
|
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)){
|
|
bits[*pos] = pfx;
|
|
lens[*pos] = pl;
|
|
xlat[*pos] = s;
|
|
(*pos)++;
|
|
}else{
|
|
pfx <<= 1;
|
|
pl++;
|
|
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);
|
|
}
|
|
}
|
|
|
|
static int build_huff_tree(VLC *vlc, Node *nodes, int head, int flags)
|
|
{
|
|
int no_zero_count = !(flags & FF_HUFFMAN_FLAG_ZERO_COUNT);
|
|
uint32_t bits[256];
|
|
int16_t lens[256];
|
|
uint8_t xlat[256];
|
|
int pos = 0;
|
|
|
|
get_tree_codes(bits, lens, xlat, nodes, head, 0, 0, &pos, no_zero_count);
|
|
return ff_init_vlc_sparse(vlc, 9, 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,
|
|
Node *nodes, HuffCmp cmp, int flags)
|
|
{
|
|
int i, j;
|
|
int cur_node;
|
|
int64_t sum = 0;
|
|
|
|
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");
|
|
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){
|
|
nodes[cur_node].sym = HNODE;
|
|
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))))
|
|
break;
|
|
FFSWAP(Node, nodes[j], nodes[j-1]);
|
|
}
|
|
cur_node++;
|
|
}
|
|
if(build_huff_tree(vlc, nodes, nb_codes*2-2, flags) < 0){
|
|
av_log(avctx, AV_LOG_ERROR, "Error building tree\n");
|
|
return -1;
|
|
}
|
|
return 0;
|
|
}
|