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Minor optimization

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This commit is contained in:
Henrik Rydgård 2024-04-30 01:01:25 +02:00
parent e010f8fcc3
commit 50bb07a6f5
2 changed files with 0 additions and 48 deletions
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47
ext/at3_standalone/fft.cpp
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@ -425,53 +425,6 @@ void imdct_calc(FFTContext *s, FFTSample *output, const FFTSample *input)
}
}
/**
* Compute MDCT of size N = 2^nbits
* @param input N samples
* @param out N/2 samples
*/
void mdct_calc(FFTContext *s, FFTSample *out, const FFTSample *input)
{
int i, j, n, n8, n4, n2, n3;
FFTDouble re, im;
const uint16_t *revtab = s->revtab;
const FFTSample *tcos = s->tcos;
const FFTSample *tsin = s->tsin;
FFTComplex *x = (FFTComplex *)out;
n = 1 << s->mdct_bits;
n2 = n >> 1;
n4 = n >> 2;
n8 = n >> 3;
n3 = 3 * n4;
/* pre rotation */
for (i = 0; i < n8; i++) {
re = (-input[2 * i + n3] - input[n3 - 1 - 2 * i]);
im = (-input[n4 + 2 * i] + input[n4 - 1 - 2 * i]);
j = revtab[i];
CMUL(x[j].re, x[j].im, re, im, -tcos[i], tsin[i]);
re = (input[2 * i] - input[n2 - 1 - 2 * i]);
im = (-input[n2 + 2 * i] - input[n - 1 - 2 * i]);
j = revtab[n8 + i];
CMUL(x[j].re, x[j].im, re, im, -tcos[n8 + i], tsin[n8 + i]);
}
fft_calc(s, x);
/* post rotation */
for (i = 0; i < n8; i++) {
FFTSample r0, i0, r1, i1;
CMUL(i1, r0, x[n8 - i - 1].re, x[n8 - i - 1].im, -tsin[n8 - i - 1], -tcos[n8 - i - 1]);
CMUL(i0, r1, x[n8 + i].re, x[n8 + i].im, -tsin[n8 + i], -tcos[n8 + i]);
x[n8 - i - 1].re = r0;
x[n8 - i - 1].im = i0;
x[n8 + i].re = r1;
x[n8 + i].im = i1;
}
}
void ff_mdct_end(FFTContext *s)
{
av_freep(&s->tcos);

1
ext/at3_standalone/fft.h
View File

@ -72,7 +72,6 @@ void fft_permute(struct FFTContext *s, FFTComplex *z);
void fft_calc(struct FFTContext *s, FFTComplex *z);
void imdct_calc(struct FFTContext *s, FFTSample *output, const FFTSample *input);
void imdct_half(struct FFTContext *s, FFTSample *output, const FFTSample *input);
void mdct_calc(struct FFTContext *s, FFTSample *output, const FFTSample *input);
#define COSTABLE(size) \
DECLARE_ALIGNED(32, FFTSample, av_cos_##size)[size/2]