[FFmpeg-devel] [PATCH 2/2] imdct15: replace the FFT with a faster PFA FFT algorithm
Peter Barfuss
bofh.h4x at gmail.com
Wed Jan 4 16:18:55 EET 2017
> + /* 15-point FFT exptab */
> + for (i = 0; i < 19; i++) {
> + if (i < 15) {
> + double theta = 2 * M_PI * i / 15;
> + s->exptab[i].re = cos(theta);
> + s->exptab[i].im = sin(theta);
> + } else { /* Wrap around to simplify fft[1]5 */
> + s->exptab[i] = s->exptab[i - 15];
Slightly surprised that you don't just leave these
pregenerated/hardcoded as it's just 24 float values. Is this for ease
of making a fixed-point version later, or some other reason?
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