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H.264: 8% faster CAVLC zero-run decoding 

Originally committed as revision 24736 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Jason Garrett-Glaser 2010-08-07 12:30:44 +00:00
parent 91af5601c1
commit b70c95e05a
1 changed files with 22 additions and 25 deletions
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47
libavcodec/h264_cavlc.c
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@ -367,7 +367,7 @@ static int decode_residual(H264Context *h, GetBitContext *gb, DCTELEM *block, in
MpegEncContext * const s = &h->s;
static const int coeff_token_table_index[17]= {0, 0, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3};
int level[16];
int zeros_left, coeff_num, coeff_token, total_coeff, i, j, trailing_ones, run_before;
int zeros_left, coeff_token, total_coeff, i, trailing_ones, run_before;
//FIXME put trailing_onex into the context
@ -488,39 +488,36 @@ static int decode_residual(H264Context *h, GetBitContext *gb, DCTELEM *block, in
zeros_left= get_vlc2(gb, (total_zeros_vlc-1)[ total_coeff ].table, TOTAL_ZEROS_VLC_BITS, 1);
}
coeff_num = zeros_left + total_coeff - 1;
j = scantable[coeff_num];
scantable += zeros_left + total_coeff - 1;
if(n > 24){
block[j] = level[0];
for(i=1;i<total_coeff;i++) {
if(zeros_left <= 0)
run_before = 0;
else if(zeros_left < 7){
block[*scantable] = level[0];
for(i=1;i<total_coeff && zeros_left > 0;i++) {
if(zeros_left < 7)
run_before= get_vlc2(gb, (run_vlc-1)[zeros_left].table, RUN_VLC_BITS, 1);
}else{
else
run_before= get_vlc2(gb, run7_vlc.table, RUN7_VLC_BITS, 2);
}
zeros_left -= run_before;
coeff_num -= 1 + run_before;
j= scantable[ coeff_num ];
block[j]= level[i];
scantable -= 1 + run_before;
block[*scantable]= level[i];
}
for(;i<total_coeff;i++) {
scantable--;
block[*scantable]= level[i];
}
}else{
block[j] = (level[0] * qmul[j] + 32)>>6;
for(i=1;i<total_coeff;i++) {
if(zeros_left <= 0)
run_before = 0;
else if(zeros_left < 7){
block[*scantable] = (level[0] * qmul[*scantable] + 32)>>6;
for(i=1;i<total_coeff && zeros_left > 0;i++) {
if(zeros_left < 7)
run_before= get_vlc2(gb, (run_vlc-1)[zeros_left].table, RUN_VLC_BITS, 1);
}else{
else
run_before= get_vlc2(gb, run7_vlc.table, RUN7_VLC_BITS, 2);
}
zeros_left -= run_before;
coeff_num -= 1 + run_before;
j= scantable[ coeff_num ];
block[j]= (level[i] * qmul[j] + 32)>>6;
scantable -= 1 + run_before;
block[*scantable]= (level[i] * qmul[*scantable] + 32)>>6;
}
for(;i<total_coeff;i++) {
scantable--;
block[*scantable]= (level[i] * qmul[*scantable] + 32)>>6;
}
}