From 7d87d56ff810b921537138f91048a932065260a1 Mon Sep 17 00:00:00 2001 From: Justin Ruggles Date: Sat, 15 Jan 2011 01:59:15 +0000 Subject: [PATCH] Take advantage of per-channel exponent and exponent strategy layout to simplify and speed up encode_exponents(). 8% faster in function. Originally committed as revision 26357 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavcodec/ac3enc.c | 33 +++++++++++++++++++-------------- 1 file changed, 19 insertions(+), 14 deletions(-) diff --git a/libavcodec/ac3enc.c b/libavcodec/ac3enc.c index 904bd8267c..61986be8f3 100644 --- a/libavcodec/ac3enc.c +++ b/libavcodec/ac3enc.c @@ -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; } } }