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add init_vlc_sparse(). faster than init_vlc() if there are lots of holes in the tables.

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Originally committed as revision 9117 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Loren Merritt 2007-05-24 17:38:56 +00:00
parent 4d5588cfb8
commit b613bacca9
2 changed files with 25 additions and 5 deletions
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18
libavcodec/bitstream.c
View File

@ -104,9 +104,10 @@ static int build_table(VLC *vlc, int table_nb_bits,
int nb_codes,
const void *bits, int bits_wrap, int bits_size,
const void *codes, int codes_wrap, int codes_size,
const void *symbols, int symbols_wrap, int symbols_size,
uint32_t code_prefix, int n_prefix, int flags)
{
int i, j, k, n, table_size, table_index, nb, n1, index, code_prefix2;
int i, j, k, n, table_size, table_index, nb, n1, index, code_prefix2, symbol;
uint32_t code;
VLC_TYPE (*table)[2];
@ -132,6 +133,10 @@ static int build_table(VLC *vlc, int table_nb_bits,
/* we accept tables with holes */
if (n <= 0)
continue;
if (!symbols)
symbol = i;
else
GET_DATA(symbol, symbols, i, symbols_wrap, symbols_size);
#if defined(DEBUG_VLC) && 0
av_log(NULL,AV_LOG_DEBUG,"i=%d n=%d code=0x%x\n", i, n, code);
#endif
@ -158,7 +163,7 @@ static int build_table(VLC *vlc, int table_nb_bits,
return -1;
}
table[j][1] = n; //bits
table[j][0] = i; //code
table[j][0] = symbol;
j++;
}
} else {
@ -189,6 +194,7 @@ static int build_table(VLC *vlc, int table_nb_bits,
index = build_table(vlc, n, nb_codes,
bits, bits_wrap, bits_size,
codes, codes_wrap, codes_size,
symbols, symbols_wrap, symbols_size,
(flags & INIT_VLC_LE) ? (code_prefix | (i << n_prefix)) : ((code_prefix << table_nb_bits) | i),
n_prefix + table_nb_bits, flags);
if (index < 0)
@ -214,6 +220,8 @@ static int build_table(VLC *vlc, int table_nb_bits,
'codes' : table which gives the bit pattern of of each vlc code.
'symbols' : table which gives the values to be returned from get_vlc().
'xxx_wrap' : give the number of bytes between each entry of the
'bits' or 'codes' tables.
@ -221,14 +229,15 @@ static int build_table(VLC *vlc, int table_nb_bits,
or 'codes' tables.
'wrap' and 'size' allows to use any memory configuration and types
(byte/word/long) to store the 'bits' and 'codes' tables.
(byte/word/long) to store the 'bits', 'codes', and 'symbols' tables.
'use_static' should be set to 1 for tables, which should be freed
with av_free_static(), 0 if free_vlc() will be used.
*/
int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
int init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes,
const void *bits, int bits_wrap, int bits_size,
const void *codes, int codes_wrap, int codes_size,
const void *symbols, int symbols_wrap, int symbols_size,
int flags)
{
vlc->bits = nb_bits;
@ -250,6 +259,7 @@ int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
if (build_table(vlc, nb_bits, nb_codes,
bits, bits_wrap, bits_size,
codes, codes_wrap, codes_size,
symbols, symbols_wrap, symbols_size,
0, 0, flags) < 0) {
av_free(vlc->table);
return -1;

12
libavcodec/bitstream.h
View File

@ -799,9 +799,19 @@ static inline void align_get_bits(GetBitContext *s)
if(n) skip_bits(s, n);
}
int init_vlc(VLC *vlc, int nb_bits, int nb_codes,
#define init_vlc(vlc, nb_bits, nb_codes,\
bits, bits_wrap, bits_size,\
codes, codes_wrap, codes_size,\
flags)\
init_vlc_sparse(vlc, nb_bits, nb_codes,\
bits, bits_wrap, bits_size,\
codes, codes_wrap, codes_size,\
NULL, 0, 0, flags)
int init_vlc_sparse(VLC *vlc, int nb_bits, int nb_codes,
const void *bits, int bits_wrap, int bits_size,
const void *codes, int codes_wrap, int codes_size,
const void *symbols, int symbols_wrap, int symbols_size,
int flags);
#define INIT_VLC_USE_STATIC 1
#define INIT_VLC_LE 2