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ffmpeg
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Use optimized function DSPContext.sad[0]() instead of calc_exp_diff(). 

90% faster compute_exp_strategy().

Originally committed as revision 26033 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles 2010-12-16 15:06:28 +00:00
parent 4f7d2fe2e3
commit 8846ee54ad
1 changed files with 7 additions and 16 deletions
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23
libavcodec/ac3enc.c
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@ -30,6 +30,7 @@
#include "libavutil/crc.h"
#include "avcodec.h"
#include "put_bits.h"
#include "dsputil.h"
#include "ac3.h"
#include "audioconvert.h"
@ -84,6 +85,7 @@ typedef struct AC3Block {
*/
typedef struct AC3EncodeContext {
PutBitContext pb; ///< bitstream writer context
DSPContext dsp;
AC3MDCTContext mdct; ///< MDCT context
AC3Block blocks[AC3_MAX_BLOCKS]; ///< per-block info
@ -512,19 +514,6 @@ static void extract_exponents(AC3EncodeContext *s)
}
/**
* Calculate the sum of absolute differences (SAD) between 2 sets of exponents.
*/
static int calc_exp_diff(uint8_t *exp1, uint8_t *exp2, int n)
{
int sum, i;
sum = 0;
for (i = 0; i < n; i++)
sum += abs(exp1[i] - exp2[i]);
return sum;
}
/**
* Exponent Difference Threshold.
* New exponents are sent if their SAD exceed this number.
@ -535,7 +524,7 @@ static int calc_exp_diff(uint8_t *exp1, uint8_t *exp2, int n)
/**
* Calculate exponent strategies for all blocks in a single channel.
*/
static void compute_exp_strategy_ch(uint8_t *exp_strategy, uint8_t **exp)
static void compute_exp_strategy_ch(AC3EncodeContext *s, uint8_t *exp_strategy, uint8_t **exp)
{
int blk, blk1;
int exp_diff;
@ -544,7 +533,7 @@ static void compute_exp_strategy_ch(uint8_t *exp_strategy, uint8_t **exp)
reused in the next frame */
exp_strategy[0] = EXP_NEW;
for (blk = 1; blk < AC3_MAX_BLOCKS; blk++) {
exp_diff = calc_exp_diff(exp[blk], exp[blk-1], AC3_MAX_COEFS);
exp_diff = s->dsp.sad[0](NULL, exp[blk], exp[blk-1], 16, 16);
if (exp_diff > EXP_DIFF_THRESHOLD)
exp_strategy[blk] = EXP_NEW;
else
@ -585,7 +574,7 @@ static void compute_exp_strategy(AC3EncodeContext *s)
exp_str1[ch][blk] = s->blocks[blk].exp_strategy[ch];
}
compute_exp_strategy_ch(exp_str1[ch], exp1[ch]);
compute_exp_strategy_ch(s, exp_str1[ch], exp1[ch]);
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++)
s->blocks[blk].exp_strategy[ch] = exp_str1[ch][blk];
@ -1769,6 +1758,8 @@ static av_cold int ac3_encode_init(AVCodecContext *avctx)
avctx->coded_frame= avcodec_alloc_frame();
dsputil_init(&s->dsp, avctx);
return 0;
init_fail:
ac3_encode_close(avctx);