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huffman: add a zero_count flag and use it in fraps 

fixes issue349

Originally committed as revision 12374 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Aurelien Jacobs 2008-03-08 18:08:16 +00:00
parent bac02ed3c5
commit a73cbf9709
3 changed files with 13 additions and 8 deletions
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3
libavcodec/fraps.c
View File

@ -94,7 +94,8 @@ static int fraps2_decode_plane(FrapsContext *s, uint8_t *dst, int stride, int w,
for(i = 0; i < 256; i++)
nodes[i].count = bytestream_get_le32(&src);
size -= 1024;
if (ff_huff_build_tree(s->avctx, &vlc, 256, nodes, huff_cmp, 0) < 0)
if (ff_huff_build_tree(s->avctx, &vlc, 256, nodes, huff_cmp,
FF_HUFFMAN_FLAG_ZERO_COUNT) < 0)
return -1;
/* we have built Huffman table and are ready to decode plane */

17
libavcodec/huffman.c
View File

@ -28,12 +28,12 @@
#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)
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 || !nodes[node].count){
if(s != HNODE || (no_zero_count && !nodes[node].count)){
bits[*pos] = pfx;
lens[*pos] = pl;
xlat[*pos] = s;
@ -41,20 +41,23 @@ static void get_tree_codes(uint32_t *bits, int16_t *lens, uint8_t *xlat, Node *n
}else{
pfx <<= 1;
pl++;
get_tree_codes(bits, lens, xlat, nodes, nodes[node].n0, pfx, pl, pos);
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);
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)
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);
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);
}
@ -98,7 +101,7 @@ int ff_huff_build_tree(AVCodecContext *avctx, VLC *vlc, int nb_codes,
}
cur_node++;
}
if(build_huff_tree(vlc, nodes, nb_codes*2-2) < 0){
if(build_huff_tree(vlc, nodes, nb_codes*2-2, flags) < 0){
av_log(avctx, AV_LOG_ERROR, "Error building tree\n");
return -1;
}

1
libavcodec/huffman.h
View File

@ -33,6 +33,7 @@ typedef struct {
} Node;
#define FF_HUFFMAN_FLAG_HNODE_FIRST 0x01
#define FF_HUFFMAN_FLAG_ZERO_COUNT 0x02
typedef int (*huff_cmp_t)(const void *va, const void *vb);
int ff_huff_build_tree(AVCodecContext *avctx, VLC *vlc, int nb_codes,