Revision 834550ea
| libavcodec/ac3enc.c | ||
|---|---|---|
| 610 | 610 |
int nb_exps, int exp_strategy, |
| 611 | 611 |
uint8_t *num_exp_groups) |
| 612 | 612 |
{
|
| 613 |
int group_size, nb_groups, i, j, k, exp_min;
|
|
| 613 |
int group_size, nb_groups, i, k;
|
|
| 614 | 614 |
|
| 615 | 615 |
group_size = exp_strategy + (exp_strategy == EXP_D45); |
| 616 | 616 |
*num_exp_groups = (nb_exps + (group_size * 3) - 4) / (3 * group_size); |
| 617 | 617 |
nb_groups = *num_exp_groups * 3; |
| 618 | 618 |
|
| 619 | 619 |
/* for each group, compute the minimum exponent */ |
| 620 |
if (exp_strategy > EXP_D15) {
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|
| 621 |
k = 1;
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|
| 622 |
for (i = 1; i <= nb_groups; i++) {
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|
| 623 |
exp_min = exp[k]; |
|
| 624 |
assert(exp_min >= 0 && exp_min <= 24);
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|
| 625 |
for (j = 1; j < group_size; j++) {
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|
| 626 |
if (exp[k+j] < exp_min)
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| 627 |
exp_min = exp[k+j];
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|
| 620 |
switch(exp_strategy) {
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|
| 621 |
case EXP_D25:
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|
| 622 |
for (i = 1, k = 1; i <= nb_groups; i++) {
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| 623 |
uint8_t exp_min = exp[k];
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|
| 624 |
if (exp[k+1] < exp_min)
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|
| 625 |
exp_min = exp[k+1];
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| 626 |
exp[i] = exp_min;
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|
| 627 |
k += 2;
|
|
| 628 | 628 |
} |
| 629 |
exp[i] = exp_min; |
|
| 630 |
k += group_size; |
|
| 631 |
} |
|
| 629 |
break; |
|
| 630 |
case EXP_D45: |
|
| 631 |
for (i = 1, k = 1; i <= nb_groups; i++) {
|
|
| 632 |
uint8_t exp_min = exp[k]; |
|
| 633 |
if (exp[k+1] < exp_min) |
|
| 634 |
exp_min = exp[k+1]; |
|
| 635 |
if (exp[k+2] < exp_min) |
|
| 636 |
exp_min = exp[k+2]; |
|
| 637 |
if (exp[k+3] < exp_min) |
|
| 638 |
exp_min = exp[k+3]; |
|
| 639 |
exp[i] = exp_min; |
|
| 640 |
k += 4; |
|
| 641 |
} |
|
| 642 |
break; |
|
| 632 | 643 |
} |
| 633 | 644 |
|
| 634 | 645 |
/* constraint for DC exponent */ |
| ... | ... | |
| 644 | 655 |
exp[i] = FFMIN(exp[i], exp[i+1] + 2); |
| 645 | 656 |
|
| 646 | 657 |
/* now we have the exponent values the decoder will see */ |
| 647 |
if (exp_strategy > EXP_D15) {
|
|
| 648 |
k = nb_groups * group_size; |
|
| 649 |
for (i = nb_groups; i > 0; i--) {
|
|
| 650 |
for (j = 0; j < group_size; j++) |
|
| 651 |
exp[k-j] = exp[i]; |
|
| 652 |
k -= group_size; |
|
| 653 |
} |
|
| 658 |
switch (exp_strategy) {
|
|
| 659 |
case EXP_D25: |
|
| 660 |
for (i = nb_groups, k = nb_groups * 2; i > 0; i--) {
|
|
| 661 |
uint8_t exp1 = exp[i]; |
|
| 662 |
exp[k--] = exp1; |
|
| 663 |
exp[k--] = exp1; |
|
| 664 |
} |
|
| 665 |
break; |
|
| 666 |
case EXP_D45: |
|
| 667 |
for (i = nb_groups, k = nb_groups * 4; i > 0; i--) {
|
|
| 668 |
exp[k] = exp[k-1] = exp[k-2] = exp[k-3] = exp[i]; |
|
| 669 |
k -= 4; |
|
| 670 |
} |
|
| 671 |
break; |
|
| 654 | 672 |
} |
| 655 | 673 |
} |
| 656 | 674 |
|
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