+
+av_cold int ff_mdct15_init(MDCT15Context **ps, int inverse, int N, double scale)
+{
+ MDCT15Context *s;
+ double alpha, theta;
+ int len2 = 15 * (1 << N);
+ int len = 2 * len2;
+ int i;
+
+ /* Tested and verified to work on everything in between */
+ if ((N < 2) || (N > 13))
+ return AVERROR(EINVAL);
+
+ s = av_mallocz(sizeof(*s));
+ if (!s)
+ return AVERROR(ENOMEM);
+
+ s->fft_n = N - 1;
+ s->len4 = len2 / 2;
+ s->len2 = len2;
+ s->inverse = inverse;
+ s->fft15 = fft15_c;
+ s->mdct = mdct15;
+ s->imdct_half = imdct15_half;
+ s->postreindex = postrotate_c;
+
+ if (ff_fft_init(&s->ptwo_fft, N - 1, s->inverse) < 0)
+ goto fail;
+
+ if (init_pfa_reindex_tabs(s))
+ goto fail;
+
+ s->tmp = av_malloc_array(len, 2 * sizeof(*s->tmp));
+ if (!s->tmp)
+ goto fail;
+
+ s->twiddle_exptab = av_malloc_array(s->len4, sizeof(*s->twiddle_exptab));
+ if (!s->twiddle_exptab)
+ goto fail;
+
+ theta = 0.125f + (scale < 0 ? s->len4 : 0);
+ scale = sqrt(fabs(scale));
+ for (i = 0; i < s->len4; i++) {
+ alpha = 2 * M_PI * (i + theta) / len;
+ s->twiddle_exptab[i].re = cosf(alpha) * scale;
+ s->twiddle_exptab[i].im = sinf(alpha) * scale;
+ }
+
+ /* 15-point FFT exptab */
+ for (i = 0; i < 19; i++) {
+ if (i < 15) {
+ double theta = (2.0f * M_PI * i) / 15.0f;
+ if (!s->inverse)
+ theta *= -1;
+ s->exptab[i].re = cosf(theta);
+ s->exptab[i].im = sinf(theta);
+ } else { /* Wrap around to simplify fft15 */
+ s->exptab[i] = s->exptab[i - 15];
+ }
+ }
+
+ /* 5-point FFT exptab */
+ s->exptab[19].re = cosf(2.0f * M_PI / 5.0f);
+ s->exptab[19].im = sinf(2.0f * M_PI / 5.0f);
+ s->exptab[20].re = cosf(1.0f * M_PI / 5.0f);
+ s->exptab[20].im = sinf(1.0f * M_PI / 5.0f);
+
+ /* Invert the phase for an inverse transform, do nothing for a forward transform */
+ if (s->inverse) {
+ s->exptab[19].im *= -1;
+ s->exptab[20].im *= -1;
+ }
+
+ if (ARCH_X86)
+ ff_mdct15_init_x86(s);
+
+ *ps = s;
+
+ return 0;
+
+fail:
+ ff_mdct15_uninit(&s);
+ return AVERROR(ENOMEM);
+}