diff options
| author | Muhammad Faiz <mfcc64@gmail.com> | 2017-07-22 06:52:45 +0700 |
|---|---|---|
| committer | Muhammad Faiz <mfcc64@gmail.com> | 2017-07-26 06:13:05 +0700 |
| commit | c8305079dae1044d7e6d978ec3251176464fb5f6 (patch) | |
| tree | b77c0b094244621c52d26271fe1b8046ecd1177c | |
| parent | 7140761481e4296723a592019a0244ebe6c1a8cf (diff) | |
avcodec/rdft: reorder calculation
old:
165188 decicycles in rdft, 65536 runs, 0 skips
165865 decicycles in irdft, 65536 runs, 0 skips
new:
142487 decicycles in rdft, 65536 runs, 0 skips
141498 decicycles in irdft, 65536 runs, 0 skips
Signed-off-by: Muhammad Faiz <mfcc64@gmail.com>
| -rw-r--r-- | libavcodec/rdft.c | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/libavcodec/rdft.c b/libavcodec/rdft.c index 194e0bc4ee..6ba7484238 100644 --- a/libavcodec/rdft.c +++ b/libavcodec/rdft.c @@ -35,7 +35,7 @@ static void rdft_calc_c(RDFTContext *s, FFTSample *data) { int i, i1, i2; - FFTComplex ev, od; + FFTComplex ev, od, odsum; const int n = 1 << s->nbits; const float k1 = 0.5; const float k2 = 0.5 - s->inverse; @@ -58,14 +58,16 @@ static void rdft_calc_c(RDFTContext *s, FFTSample *data) i2 = n-i1; \ /* Separate even and odd FFTs */ \ ev.re = k1*(data[i1 ]+data[i2 ]); \ - od.im = -k2*(data[i1 ]-data[i2 ]); \ + od.im = k2*(data[i2 ]-data[i1 ]); \ ev.im = k1*(data[i1+1]-data[i2+1]); \ od.re = k2*(data[i1+1]+data[i2+1]); \ /* Apply twiddle factors to the odd FFT and add to the even FFT */ \ - data[i1 ] = ev.re + od.re*tcos[i] sign0 od.im*tsin[i]; \ - data[i1+1] = ev.im + od.im*tcos[i] sign1 od.re*tsin[i]; \ - data[i2 ] = ev.re - od.re*tcos[i] sign1 od.im*tsin[i]; \ - data[i2+1] = -ev.im + od.im*tcos[i] sign1 od.re*tsin[i]; \ + odsum.re = od.re*tcos[i] sign0 od.im*tsin[i]; \ + odsum.im = od.im*tcos[i] sign1 od.re*tsin[i]; \ + data[i1 ] = ev.re + odsum.re; \ + data[i1+1] = ev.im + odsum.im; \ + data[i2 ] = ev.re - odsum.re; \ + data[i2+1] = odsum.im - ev.im; \ } if (s->negative_sin) { |