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| author | Mans Rullgard <mans@mansr.com> | 2012-08-10 01:14:32 +0100 |
|---|---|---|
| committer | Mans Rullgard <mans@mansr.com> | 2012-08-10 12:18:38 +0100 |
| commit | 52aa3015a3c895cf74e555c4bb56c08cd067383e (patch) | |
| tree | cb304e7a3d6d5f654c2c30184c8a4b5d1173ed28 /libavcodec | |
| parent | e141cf2c5794cd9884f2806b7766a1e0bb47ebe5 (diff) | |
| download | ffmpeg-52aa3015a3c895cf74e555c4bb56c08cd067383e.tar.gz | |
g723.1: simplify and fix multiplication overflow
In 16-bit arithmetic, x * 0xffffc is simply x * -4 with extra overflows,
(and the constant was probably meant to be 0xfffc). Combined with the
shift, this simplifies to -x >> 1. Finally, clearing the low two bits
with a 32-bit mask and switching to a 32-bit type allows more efficient
code on 32-bit machines.
Signed-off-by: Mans Rullgard <mans@mansr.com>
Diffstat (limited to 'libavcodec')
| -rw-r--r-- | libavcodec/g723_1.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/libavcodec/g723_1.c b/libavcodec/g723_1.c index c337deb881..53b9adedd4 100644 --- a/libavcodec/g723_1.c +++ b/libavcodec/g723_1.c @@ -956,7 +956,7 @@ static void formant_postfilter(G723_1_Context *p, int16_t *lpc, int16_t *buf) signal_ptr = filter_signal + LPC_ORDER; for (i = 0; i < SUBFRAMES; i++) { int16_t temp_vector[SUBFRAME_LEN]; - int16_t temp; + int temp; int auto_corr[2]; int scale, energy; @@ -975,7 +975,7 @@ static void formant_postfilter(G723_1_Context *p, int16_t *lpc, int16_t *buf) temp = (auto_corr[0] >> 2) / temp; } p->reflection_coef = (3 * p->reflection_coef + temp + 2) >> 2; - temp = (p->reflection_coef * 0xffffc >> 3) & 0xfffc; + temp = -p->reflection_coef >> 1 & ~3; /* Compensation filter */ for (j = 0; j < SUBFRAME_LEN; j++) { |