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Code Issues Releases Activity

avcodec/ituh263dec: Simplify AIC handling

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Possible by using block_index.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt
2025-05-25 20:17:39 +02:00
parent 822be72f0a
commit 950137a7c8
1 changed files with 13 additions and 22 deletions
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35
libavcodec/ituh263dec.c
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@ -448,34 +448,25 @@ static void h263_decode_dquant(MpegEncContext *s){
static void h263_pred_acdc(MpegEncContext * s, int16_t *block, int n)
{
int x, y, wrap, a, c, pred_dc, scale;
int16_t *dc_val, *ac_val, *ac_val1;
int wrap, a, c, pred_dc, scale;
const int xy = s->block_index[n];
int16_t *const dc_val = s->dc_val[0] + xy;
int16_t *const ac_val = (s->ac_val[0] + xy)[0];
/* find prediction */
if (n < 4) {
x = 2 * s->mb_x + (n & 1);
y = 2 * s->mb_y + (n>> 1);
wrap = s->b8_stride;
dc_val = s->dc_val[0];
ac_val = s->ac_val[0][0];
scale = s->y_dc_scale;
} else {
x = s->mb_x;
y = s->mb_y;
wrap = s->mb_stride;
dc_val = s->dc_val[n - 4 + 1];
ac_val = s->ac_val[n - 4 + 1][0];
scale = s->c_dc_scale;
}
ac_val += ((y) * wrap + (x)) * 16;
ac_val1 = ac_val;
/* B C
* A X
*/
a = dc_val[(x - 1) + (y) * wrap];
c = dc_val[(x) + (y - 1) * wrap];
a = dc_val[-1];
c = dc_val[-wrap];
/* No prediction outside GOB boundary */
if (s->first_slice_line && n != 3) {
@ -488,18 +479,18 @@ static void h263_pred_acdc(MpegEncContext * s, int16_t *block, int n)
if (s->h263_aic_dir) {
/* left prediction */
if (a != 1024) {
ac_val -= 16;
int16_t *const ac_val2 = ac_val - 16;
for (int i = 1; i < 8; i++) {
block[s->idsp.idct_permutation[i << 3]] += ac_val[i];
block[s->idsp.idct_permutation[i << 3]] += ac_val2[i];
}
pred_dc = a;
}
} else {
/* top prediction */
if (c != 1024) {
ac_val -= 16 * wrap;
int16_t *const ac_val2 = ac_val - 16 * wrap;
for (int i = 1; i < 8; i++) {
block[s->idsp.idct_permutation[i]] += ac_val[i + 8];
block[s->idsp.idct_permutation[i]] += ac_val2[i + 8];
}
pred_dc = c;
}
@ -523,14 +514,14 @@ static void h263_pred_acdc(MpegEncContext * s, int16_t *block, int n)
block[0] |= 1;
/* Update AC/DC tables */
dc_val[(x) + (y) * wrap] = block[0];
*dc_val = block[0];
/* left copy */
for (int i = 1; i < 8; i++)
ac_val1[i] = block[s->idsp.idct_permutation[i << 3]];
ac_val[i] = block[s->idsp.idct_permutation[i << 3]];
/* top copy */
for (int i = 1; i < 8; i++)
ac_val1[8 + i] = block[s->idsp.idct_permutation[i]];
ac_val[8 + i] = block[s->idsp.idct_permutation[i]];
}
static int h263_decode_block(MpegEncContext * s, int16_t * block,