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unified CAVLC level decoding LUT. 

Quite a bit faster (HPCVMOLQ_BRCM_B.264 was 3% faster here)

Originally committed as revision 16291 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2008-12-23 17:49:38 +00:00
parent 5dd9799de8
commit 8140955d39
1 changed files with 45 additions and 4 deletions
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49
libavcodec/h264.c
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@ -101,6 +101,9 @@ static const int left_block_options[4][8]={
{0,2,0,2,7,10,7,10}
};
#define LEVEL_TAB_BITS 8
static int8_t cavlc_level_tab[7][1<<LEVEL_TAB_BITS][2];
static void fill_caches(H264Context *h, int mb_type, int for_deblock){
MpegEncContext * const s = &h->s;
const int mb_xy= h->mb_xy;
@ -1875,6 +1878,31 @@ static void hl_motion(H264Context *h, uint8_t *dest_y, uint8_t *dest_cb, uint8_t
prefetch_motion(h, 1);
}
static av_cold void init_cavlc_level_tab(void){
int suffix_length, mask;
unsigned int i;
for(suffix_length=0; suffix_length<7; suffix_length++){
for(i=0; i<(1<<LEVEL_TAB_BITS); i++){
int prefix= LEVEL_TAB_BITS - av_log2(2*i);
int level_code= (prefix<<suffix_length) + (i>>(LEVEL_TAB_BITS-prefix-1-suffix_length)) - (1<<suffix_length);
mask= -(level_code&1);
level_code= (((2+level_code)>>1) ^ mask) - mask;
if(prefix + 1 + suffix_length <= LEVEL_TAB_BITS){
cavlc_level_tab[suffix_length][i][0]= level_code;
cavlc_level_tab[suffix_length][i][1]= prefix + 1 + suffix_length;
}else if(prefix + 1 <= LEVEL_TAB_BITS){
cavlc_level_tab[suffix_length][i][0]= prefix+100;
cavlc_level_tab[suffix_length][i][1]= prefix + 1;
}else{
cavlc_level_tab[suffix_length][i][0]= LEVEL_TAB_BITS+100;
cavlc_level_tab[suffix_length][i][1]= LEVEL_TAB_BITS;
}
}
}
}
static av_cold void decode_init_vlc(void){
static int done = 0;
@ -1941,6 +1969,8 @@ static av_cold void decode_init_vlc(void){
&run_len [6][0], 1, 1,
&run_bits[6][0], 1, 1,
INIT_VLC_USE_NEW_STATIC);
init_cavlc_level_tab();
}
}
@ -4137,8 +4167,16 @@ static int decode_residual(H264Context *h, GetBitContext *gb, DCTELEM *block, in
//remaining coefficients have suffix_length > 0
for(i=trailing_ones+1;i<total_coeff;i++) {
static const int suffix_limit[7] = {0,5,11,23,47,95,INT_MAX };
prefix = get_level_prefix(gb);
static const unsigned int suffix_limit[7] = {0,3,6,12,24,48,INT_MAX };
int bitsi= show_bits(gb, LEVEL_TAB_BITS);
level_code= cavlc_level_tab[suffix_length][bitsi][0];
skip_bits(gb, cavlc_level_tab[suffix_length][bitsi][1]);
if(level_code >= 100){
prefix= level_code - 100;
if(prefix == LEVEL_TAB_BITS){
prefix += get_level_prefix(gb);
}
if(prefix<15){
level_code = (prefix<<suffix_length) + get_bits(gb, suffix_length);
}else{
@ -4147,8 +4185,11 @@ static int decode_residual(H264Context *h, GetBitContext *gb, DCTELEM *block, in
level_code += (1<<(prefix-3))-4096;
}
mask= -(level_code&1);
level[i]= (((2+level_code)>>1) ^ mask) - mask;
if(level_code > suffix_limit[suffix_length])
level_code= (((2+level_code)>>1) ^ mask) - mask;
}
level[i]= level_code;
if(suffix_limit[suffix_length] + level_code > 2U*suffix_limit[suffix_length])
suffix_length++;
}
}