---
libavcodec/ac3enc.c | 23 ++++++++++++++---------
1 files changed, 14 insertions(+), 9 deletions(-)
diff --git libavcodec/ac3enc.c libavcodec/ac3enc.c
index 994c316..238a553 100644
--- libavcodec/ac3enc.c
+++ libavcodec/ac3enc.c
@@ -242,31 +242,36 @@ static void fft(IComplex *z, int ln)
static void mdct512(int32_t *out, int16_t *in)
{
int i, re, im, re1, im1;
+ int n, n2, n4;
int16_t rot[MDCT_SAMPLES];
IComplex x[MDCT_SAMPLES/4];
+ n = MDCT_SAMPLES;
+ n2 = n >> 1;
+ n4 = n >> 2;
+
/* shift to simplify computations */
- for (i = 0; i < MDCT_SAMPLES/4; i++)
- rot[i] = -in[i + 3*MDCT_SAMPLES/4];
- for (; i < MDCT_SAMPLES; i++)
- rot[i] = in[i - MDCT_SAMPLES/4];
+ for (i = 0; i < n4; i++)
+ rot[i] = -in[i+3*n4];
+ for (; i < n; i++)
+ rot[i] = in[i-n4];
/* pre rotation */
- for (i = 0; i < MDCT_SAMPLES/4; i++) {
- re = ((int)rot[2*i] - (int)rot[MDCT_SAMPLES-1-2*i]) >> 1;
- im = -((int)rot[MDCT_SAMPLES/2+2*i] - (int)rot[MDCT_SAMPLES/2-1-2*i]) >> 1;
+ for (i = 0; i < n4; i++) {
+ re = ((int)rot[ 2*i] - (int)rot[ n-1-2*i]) >> 1;
+ im = -((int)rot[n2+2*i] - (int)rot[n2-1-2*i]) >> 1;
CMUL(x[i].re, x[i].im, re, im, -xcos1[i], xsin1[i]);
}
fft(x, MDCT_NBITS - 2);
/* post rotation */
- for (i = 0; i < MDCT_SAMPLES/4; i++) {
+ for (i = 0; i < n4; i++) {
re = x[i].re;
im = x[i].im;
CMUL(re1, im1, re, im, xsin1[i], xcos1[i]);
out[2*i] = im1;
- out[MDCT_SAMPLES/2-1-2*i] = re1;
+ out[n2-1-2*i] = re1;
}
}
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