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af_biquad: avoid subtraction in loop 

17% faster
Note the speedup is smaller if its done before
storing in the context (gcc 4.6.3 core i7)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2013-02-07 19:39:08 +01:00
parent 9f956611e3
commit a00c4b4db0
1 changed files with 5 additions and 3 deletions
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8
libavfilter/af_biquads.c
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@ -181,9 +181,11 @@ static void biquad_## name (const void *input, void *output, int len, \
double o1 = *out1; \
double o2 = *out2; \
int i; \
a1 = -a1; \
a2 = -a2; \
\
for (i = 0; i+1 < len; i++) { \
o2 = i2 * b2 + i1 * b1 + ibuf[i] * b0 - o2 * a2 - o1 * a1; \
o2 = i2 * b2 + i1 * b1 + ibuf[i] * b0 + o2 * a2 + o1 * a1; \
i2 = ibuf[i]; \
if (o2 < min) { \
av_log(NULL, AV_LOG_WARNING, "clipping\n"); \
@ -195,7 +197,7 @@ static void biquad_## name (const void *input, void *output, int len, \
obuf[i] = o2; \
} \
i++; \
o1 = i1 * b2 + i2 * b1 + ibuf[i] * b0 - o1 * a2 - o2 * a1; \
o1 = i1 * b2 + i2 * b1 + ibuf[i] * b0 + o1 * a2 + o2 * a1; \
i1 = ibuf[i]; \
if (o1 < min) { \
av_log(NULL, AV_LOG_WARNING, "clipping\n"); \
@ -208,7 +210,7 @@ static void biquad_## name (const void *input, void *output, int len, \
} \
} \
if (i < len) { \
double o0 = ibuf[i] * b0 + i1 * b1 + i2 * b2 - o1 * a1 - o2 * a2; \
double o0 = ibuf[i] * b0 + i1 * b1 + i2 * b2 + o1 * a1 + o2 * a2; \
i2 = i1; \
i1 = ibuf[i]; \
o2 = o1; \