virtualenv/FFmpeg
1
0
Fork 0
mirror of https://github.com/FFmpeg/FFmpeg.git synced 2024-12-23 12:43:46 +02:00
Code Issues Releases Activity

try to avoid l3_unscale() by using a table

Browse Source 
Originally committed as revision 6083 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2006-08-25 11:55:20 +00:00
parent f8347c4167
commit 55017f35da
1 changed files with 25 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

29
libavcodec/mpegaudiodec.c
View File

@ -174,6 +174,7 @@ static uint16_t band_index_long[9][23];
static int8_t *table_4_3_exp;
static uint32_t *table_4_3_value;
static uint32_t exp_table[512];
static uint32_t expval_table[512][16];
/* intensity stereo coef table */
static int32_t is_table[2][16];
static int32_t is_table_lsf[2][2][16];
@ -429,10 +430,12 @@ static int decode_init(AVCodecContext * avctx)
// av_log(NULL, AV_LOG_DEBUG, "%d %d %f\n", i, m, pow((double)i, 4.0 / 3.0));
table_4_3_exp[i] = -e;
}
for(i=0; i<512; i++){
int exponent= i-400;
double f= pow(1, 4.0 / 3.0) * pow(2, exponent*0.25 + FRAC_BITS + 5);
exp_table[i]= lrintf(f);
for(i=0; i<512*16; i++){
int exponent= (i>>4)-400;
double f= pow(i&15, 4.0 / 3.0) * pow(2, exponent*0.25 + FRAC_BITS + 5);
expval_table[exponent+400][i&15]= lrintf(f);
if((i&15)==1)
exp_table[exponent+400]= lrintf(f);
}
for(i=0;i<7;i++) {
@ -1717,9 +1720,18 @@ static int huffman_decode(MPADecodeContext *s, GranuleDef *g,
dprintf("region=%d n=%d x=%d y=%d exp=%d\n",
i, g->region_size[i] - j, x, y, exponents[s_index]);
if (x) {
#if 0
if (x == 15)
x += get_bitsz(&s->gb, linbits);
v = l3_unscale(x, exponents[s_index]);
#else
if (x < 15){
v = expval_table[ exponents[s_index] + 400 ][ x ];
}else{
x += get_bitsz(&s->gb, linbits);
v = l3_unscale(x, exponents[s_index]);
}
#endif
if (get_bits1(&s->gb))
v = -v;
} else {
@ -1727,9 +1739,18 @@ static int huffman_decode(MPADecodeContext *s, GranuleDef *g,
}
g->sb_hybrid[s_index++] = v;
if (y) {
#if 0
if (y == 15)
y += get_bitsz(&s->gb, linbits);
v = l3_unscale(y, exponents[s_index]);
#else
if (y < 15){
v = expval_table[ exponents[s_index] + 400 ][ y ];
}else{
y += get_bitsz(&s->gb, linbits);
v = l3_unscale(y, exponents[s_index]);
}
#endif
if (get_bits1(&s->gb))
v = -v;
} else {