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ac3enc: avoid memcpy() of exponents and baps in EXP_REUSE case by using 

exponent reference blocks.
This commit is contained in:
Justin Ruggles 2011-03-28 14:01:27 -04:00
parent 42315dabce
commit c4549bd66a
1 changed files with 17 additions and 17 deletions
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34
libavcodec/ac3enc.c
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@ -112,6 +112,7 @@ typedef struct AC3Block {
uint8_t coeff_shift[AC3_MAX_CHANNELS]; ///< fixed-point coefficient shift values
uint8_t new_rematrixing_strategy; ///< send new rematrixing flags in this block
uint8_t rematrixing_flags[4]; ///< rematrixing flags
struct AC3Block *exp_ref_block[AC3_MAX_CHANNELS]; ///< reference blocks for EXP_REUSE
} AC3Block;
/**
@ -692,7 +693,7 @@ static void encode_exponents_blk_ch(uint8_t *exp, int nb_exps, int exp_strategy)
static void encode_exponents(AC3EncodeContext *s)
{
int blk, blk1, ch;
uint8_t *exp, *exp1, *exp_strategy;
uint8_t *exp, *exp_strategy;
int nb_coefs, num_reuse_blocks;
for (ch = 0; ch < s->channels; ch++) {
@ -704,9 +705,13 @@ static void encode_exponents(AC3EncodeContext *s)
while (blk < AC3_MAX_BLOCKS) {
blk1 = blk + 1;
/* count the number of EXP_REUSE blocks after the current block */
while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE)
/* count the number of EXP_REUSE blocks after the current block
and set exponent reference block pointers */
s->blocks[blk].exp_ref_block[ch] = &s->blocks[blk];
while (blk1 < AC3_MAX_BLOCKS && exp_strategy[blk1] == EXP_REUSE) {
s->blocks[blk1].exp_ref_block[ch] = &s->blocks[blk];
blk1++;
}
num_reuse_blocks = blk1 - blk - 1;
/* for the EXP_REUSE case we select the min of the exponents */
@ -714,15 +719,8 @@ static void encode_exponents(AC3EncodeContext *s)
encode_exponents_blk_ch(exp, nb_coefs, exp_strategy[blk]);
/* copy encoded exponents for reuse case */
exp1 = exp + AC3_MAX_COEFS;
while (blk < blk1-1) {
memcpy(exp1, exp, nb_coefs * sizeof(*exp));
exp1 += AC3_MAX_COEFS;
blk++;
}
exp += AC3_MAX_COEFS * (num_reuse_blocks + 1);
blk = blk1;
exp = exp1;
}
}
}
@ -1035,7 +1033,7 @@ static int bit_alloc(AC3EncodeContext *s, int snr_offset)
reset_block_bap(s);
mantissa_bits = 0;
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
AC3Block *block = &s->blocks[blk];
AC3Block *block;
// initialize grouped mantissa counts. these are set so that they are
// padded to the next whole group size when bits are counted in
// compute_mantissa_size_final
@ -1047,9 +1045,8 @@ static int bit_alloc(AC3EncodeContext *s, int snr_offset)
blocks within a frame are the exponent values. We can take
advantage of that by reusing the bit allocation pointers
whenever we reuse exponents. */
if (s->exp_strategy[ch][blk] == EXP_REUSE) {
memcpy(block->bap[ch], s->blocks[blk-1].bap[ch], AC3_MAX_COEFS);
} else {
block = s->blocks[blk].exp_ref_block[ch];
if (s->exp_strategy[ch][blk] != EXP_REUSE) {
ff_ac3_bit_alloc_calc_bap(block->mask[ch], block->psd[ch], 0,
s->nb_coefs[ch], snr_offset,
s->bit_alloc.floor, ff_ac3_bap_tab,
@ -1352,12 +1349,14 @@ static void quantize_mantissas(AC3EncodeContext *s)
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
AC3Block *block = &s->blocks[blk];
AC3Block *ref_block;
s->mant1_cnt = s->mant2_cnt = s->mant4_cnt = 0;
s->qmant1_ptr = s->qmant2_ptr = s->qmant4_ptr = NULL;
for (ch = 0; ch < s->channels; ch++) {
ref_block = block->exp_ref_block[ch];
quantize_mantissas_blk_ch(s, block->fixed_coef[ch],
block->exp[ch], block->bap[ch],
ref_block->exp[ch], ref_block->bap[ch],
block->qmant[ch], s->nb_coefs[ch]);
}
}
@ -1516,9 +1515,10 @@ static void output_audio_block(AC3EncodeContext *s, int blk)
/* mantissas */
for (ch = 0; ch < s->channels; ch++) {
int b, q;
AC3Block *ref_block = block->exp_ref_block[ch];
for (i = 0; i < s->nb_coefs[ch]; i++) {
q = block->qmant[ch][i];
b = block->bap[ch][i];
b = ref_block->bap[ch][i];
switch (b) {
case 0: break;
case 1: if (q != 128) put_bits(&s->pb, 5, q); break;