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Take advantage of per-channel exponent and exponent strategy layout to

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simplify and speed up encode_exponents().
8% faster in function.

Originally committed as revision 26357 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles 2011-01-15 01:59:15 +00:00
parent 5bff8590f3
commit 7d87d56ff8
1 changed files with 19 additions and 14 deletions
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33
libavcodec/ac3enc.c
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@ -587,31 +587,36 @@ static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy)
*/
static void encode_exponents(AC3EncodeContext *s)
{
int blk, blk1, blk2, ch;
AC3Block *block, *block1, *block2;
int blk, blk1, ch;
uint8_t *exp, *exp1, *exp_strategy;
int nb_coefs;
for (ch = 0; ch < s->channels; ch++) {
exp = s->blocks[0].exp[ch];
exp_strategy = s->exp_strategy[ch];
nb_coefs = s->nb_coefs[ch];
blk = 0;
block = &s->blocks[0];
while (blk < AC3_MAX_BLOCKS) {
blk1 = blk + 1;
block1 = block + 1;
exp1 = exp + AC3_MAX_COEFS;
/* for the EXP_REUSE case we select the min of the exponents */
while (blk1 < AC3_MAX_BLOCKS && s->exp_strategy[ch][blk1] == EXP_REUSE) {
exponent_min(block->exp[ch], block1->exp[ch], s->nb_coefs[ch]);
while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE) {
exponent_min(exp, exp1, nb_coefs);
blk1++;
block1++;
exp1 += AC3_MAX_COEFS;
}
encode_exponents_blk_ch(block->exp[ch], s->nb_coefs[ch],
s->exp_strategy[ch][blk]);
encode_exponents_blk_ch(exp, nb_coefs,
exp_strategy[blk]);
/* copy encoded exponents for reuse case */
block2 = block + 1;
for (blk2 = blk+1; blk2 < blk1; blk2++, block2++) {
memcpy(block2->exp[ch], block->exp[ch],
s->nb_coefs[ch] * sizeof(uint8_t));
exp1 = exp + AC3_MAX_COEFS;
while (blk < blk1-1) {
memcpy(exp1, exp, nb_coefs * sizeof(*exp));
exp1 += AC3_MAX_COEFS;
blk++;
}
blk = blk1;
block = block1;
exp = exp1;
}
}
}