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Merge decode_cabac_mb_type_b() into calling code.

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This avoids a conditional branch and is about 3 cpu cyclues faster.

Originally committed as revision 21838 to svn://svn.ffmpeg.org/ffmpeg/trunk
release/0.6
Michael Niedermayer 15 years ago
parent 6713b6b120
commit f4060611e9
1 changed files with 34 additions and 44 deletions
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  1. 76
      libavcodec/h264_cabac.c

76
libavcodec/h264_cabac.c
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@ -750,44 +750,6 @@ static int decode_cabac_intra_mb_type(H264Context *h, int ctx_base, int intra_sl
return mb_type;
}
static int decode_cabac_mb_type_b( H264Context *h ) {
MpegEncContext * const s = &h->s;
const int mba_xy = h->left_mb_xy[0];
const int mbb_xy = h->top_mb_xy;
int ctx = 0;
int bits;
assert(h->slice_type_nos == FF_B_TYPE);
if( h->slice_table[mba_xy] == h->slice_num && !IS_DIRECT( s->current_picture.mb_type[mba_xy] ) )
ctx++;
if( h->slice_table[mbb_xy] == h->slice_num && !IS_DIRECT( s->current_picture.mb_type[mbb_xy] ) )
ctx++;
if( !get_cabac_noinline( &h->cabac, &h->cabac_state[27+ctx] ) )
return 0; /* B_Direct_16x16 */
if( !get_cabac_noinline( &h->cabac, &h->cabac_state[27+3] ) ) {
return 1 + get_cabac_noinline( &h->cabac, &h->cabac_state[27+5] ); /* B_L[01]_16x16 */
}
bits = get_cabac_noinline( &h->cabac, &h->cabac_state[27+4] ) << 3;
bits|= get_cabac_noinline( &h->cabac, &h->cabac_state[27+5] ) << 2;
bits|= get_cabac_noinline( &h->cabac, &h->cabac_state[27+5] ) << 1;
bits|= get_cabac_noinline( &h->cabac, &h->cabac_state[27+5] );
if( bits < 8 )
return bits + 3; /* B_Bi_16x16 through B_L1_L0_16x8 */
else if( bits == 13 ) {
return decode_cabac_intra_mb_type(h, 32, 0) + 23;
} else if( bits == 14 )
return 11; /* B_L1_L0_8x16 */
else if( bits == 15 )
return 22; /* B_8x8 */
bits= ( bits<<1 ) | get_cabac_noinline( &h->cabac, &h->cabac_state[27+5] );
return bits - 4; /* B_L0_Bi_* through B_Bi_Bi_* */
}
static int decode_cabac_mb_skip( H264Context *h, int mb_x, int mb_y ) {
MpegEncContext * const s = &h->s;
int mba_xy, mbb_xy;
@ -1301,14 +1263,42 @@ int ff_h264_decode_mb_cabac(H264Context *h) {
compute_mb_neighbors(h);
if( h->slice_type_nos == FF_B_TYPE ) {
mb_type = decode_cabac_mb_type_b( h );
if( mb_type < 23 ){
partition_count= b_mb_type_info[mb_type].partition_count;
mb_type= b_mb_type_info[mb_type].type;
const int mba_xy = h->left_mb_xy[0];
const int mbb_xy = h->top_mb_xy;
int ctx = 0;
assert(h->slice_type_nos == FF_B_TYPE);
if( h->slice_table[mba_xy] == h->slice_num && !IS_DIRECT( s->current_picture.mb_type[mba_xy] ) )
ctx++;
if( h->slice_table[mbb_xy] == h->slice_num && !IS_DIRECT( s->current_picture.mb_type[mbb_xy] ) )
ctx++;
if( !get_cabac_noinline( &h->cabac, &h->cabac_state[27+ctx] ) ){
mb_type= 0; /* B_Direct_16x16 */
}else if( !get_cabac_noinline( &h->cabac, &h->cabac_state[27+3] ) ) {
mb_type= 1 + get_cabac_noinline( &h->cabac, &h->cabac_state[27+5] ); /* B_L[01]_16x16 */
}else{
mb_type -= 23;
int bits;
bits = get_cabac_noinline( &h->cabac, &h->cabac_state[27+4] ) << 3;
bits|= get_cabac_noinline( &h->cabac, &h->cabac_state[27+5] ) << 2;
bits|= get_cabac_noinline( &h->cabac, &h->cabac_state[27+5] ) << 1;
bits|= get_cabac_noinline( &h->cabac, &h->cabac_state[27+5] );
if( bits < 8 ){
mb_type= bits + 3; /* B_Bi_16x16 through B_L1_L0_16x8 */
}else if( bits == 13 ){
mb_type= decode_cabac_intra_mb_type(h, 32, 0);
goto decode_intra_mb;
}else if( bits == 14 ){
mb_type= 11; /* B_L1_L0_8x16 */
}else if( bits == 15 ){
mb_type= 22; /* B_8x8 */
}else{
bits= ( bits<<1 ) | get_cabac_noinline( &h->cabac, &h->cabac_state[27+5] );
mb_type= bits - 4; /* B_L0_Bi_* through B_Bi_Bi_* */
}
}
partition_count= b_mb_type_info[mb_type].partition_count;
mb_type= b_mb_type_info[mb_type].type;
} else if( h->slice_type_nos == FF_P_TYPE ) {
if( get_cabac_noinline( &h->cabac, &h->cabac_state[14] ) == 0 ) {
/* P-type */

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