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cleanup of decode_cabac_residual() 

Originally committed as revision 3626 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Michael Niedermayer 2004-10-23 15:59:01 +00:00
parent d6b0c1bbf8
commit 9af1ec8e9a
1 changed files with 46 additions and 65 deletions
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111
libavcodec/h264.c
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@ -4264,15 +4264,13 @@ static int decode_cabac_residual( H264Context *h, DCTELEM *block, int cat, int n
const int mb_xy = h->s.mb_x + h->s.mb_y*h->s.mb_stride;
const uint16_t *qmul= dequant_coeff[qp];
static const int significant_coeff_flag_offset[5] = { 0, 15, 29, 44, 47 };
static const int last_significant_coeff_flag_offset[5] = { 0, 15, 29, 44, 47 };
static const int coeff_abs_level_m1_offset[5] = { 0, 10, 20, 30, 39 };
static const int coeff_abs_level_m1_offset[5] = {227+ 0, 227+10, 227+20, 227+30, 227+39 };
int coeff[16];
int index[16];
int last = 0;
int i, last;
int coeff_count = 0;
int nz[16] = {0};
int i;
int abslevel1 = 0;
int abslevelgt1 = 0;
@ -4294,26 +4292,17 @@ static int decode_cabac_residual( H264Context *h, DCTELEM *block, int cat, int n
return 0;
}
while( last < max_coeff - 1 ) {
int ctx = FFMIN( last, max_coeff - 2 );
if( get_cabac( &h->cabac, &h->cabac_state[105+significant_coeff_flag_offset[cat]+ctx] ) == 0 ) {
nz[last++] = 0;
}
else {
nz[last++] = 1;
coeff_count++;
if( get_cabac( &h->cabac, &h->cabac_state[166+last_significant_coeff_flag_offset[cat]+ctx] ) ) {
while( last < max_coeff ) {
nz[last++] = 0;
}
for(last= 0; last < max_coeff - 1; last++) {
if( get_cabac( &h->cabac, &h->cabac_state[105+significant_coeff_flag_offset[cat]+last] )) {
index[coeff_count++] = last;
if( get_cabac( &h->cabac, &h->cabac_state[166+significant_coeff_flag_offset[cat]+last] ) ) {
last= max_coeff;
break;
}
}
}
if( last == max_coeff -1 ) {
nz[last++] = 1;
coeff_count++;
index[coeff_count++] = last;
}
if( cat == 0 && coeff_count > 0 )
@ -4326,61 +4315,53 @@ static int decode_cabac_residual( H264Context *h, DCTELEM *block, int cat, int n
h->non_zero_count_cache[scan8[16+n]] = coeff_count;
for( i = coeff_count - 1; i >= 0; i-- ) {
int coeff_abs_m1;
int ctx = (abslevelgt1 != 0 ? 0 : FFMIN( 4, abslevel1 + 1 )) + coeff_abs_level_m1_offset[cat];
if( get_cabac( &h->cabac, &h->cabac_state[227+ctx] ) == 0 ) {
coeff_abs_m1 = 0;
} else {
coeff_abs_m1 = 1;
ctx = 5 + FFMIN( 4, abslevelgt1 ) + coeff_abs_level_m1_offset[cat];
while( coeff_abs_m1 < 14 && get_cabac( &h->cabac, &h->cabac_state[227+ctx] ) ) {
coeff_abs_m1++;
}
}
if( coeff_abs_m1 >= 14 ) {
int j = 0;
while( get_cabac_bypass( &h->cabac ) ) {
coeff_abs_m1 += 1 << j;
j++;
}
while( j-- ) {
if( get_cabac_bypass( &h->cabac ) )
coeff_abs_m1 += 1 << j ;
}
}
if( get_cabac_bypass( &h->cabac ) )
coeff[i] = -1 *( coeff_abs_m1 + 1 );
else
coeff[i] = coeff_abs_m1 + 1;
if( coeff_abs_m1 == 0 )
if( get_cabac( &h->cabac, &h->cabac_state[ctx] ) == 0 ) {
if( get_cabac_bypass( &h->cabac ) )
coeff[i] = -1;
else
coeff[i] = 1;
abslevel1++;
else
} else {
int coeff_abs = 2;
ctx = 5 + FFMIN( 4, abslevelgt1 ) + coeff_abs_level_m1_offset[cat];
while( coeff_abs < 15 && get_cabac( &h->cabac, &h->cabac_state[ctx] ) ) {
coeff_abs++;
}
if( coeff_abs >= 15 ) {
int j = 0;
while( get_cabac_bypass( &h->cabac ) ) {
coeff_abs += 1 << j;
j++;
}
while( j-- ) {
if( get_cabac_bypass( &h->cabac ) )
coeff_abs += 1 << j ;
}
}
if( get_cabac_bypass( &h->cabac ) )
coeff[i] = -coeff_abs;
else
coeff[i] = coeff_abs;
abslevelgt1++;
}
}
if( cat == 0 || cat == 3 ) { /* DC */
int j;
for( i = 0, j = 0; j < coeff_count; i++ ) {
if( nz[i] ) {
block[scantable[i]] = coeff[j];
j++;
}
for(i = 0; i < coeff_count; i++) {
block[scantable[ index[i] ]] = coeff[i];
}
} else { /* AC */
int j;
for( i = 0, j = 0; j < coeff_count; i++ ) {
if( nz[i] ) {
block[scantable[i]] = coeff[j] * qmul[scantable[i]];
j++;
}
for(i = 0; i < coeff_count; i++) {
int j= scantable[index[i]];
block[j] = coeff[i] * qmul[j];
}
}
return 0;