/* * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include "libavutil/avassert.h" #include "libavutil/error.h" #include "libavutil/libm.h" #include "libavutil/mathematics.h" #include "libavutil/attributes.h" #include "libavutil/mem.h" #include "kbdwin.h" av_cold static int kbd_window_init(float *float_window, int *int_window, float alpha, int n) { int i; double sum = 0.0, tmp; double scale = 0.0; double temp_small[FF_KBD_WINDOW_MAX / 2 + 1]; double *temp= n<=FF_KBD_WINDOW_MAX ? temp_small : av_malloc((n/2+1) * sizeof(*temp)); double alpha2 = 4 * (alpha * M_PI / n) * (alpha * M_PI / n); if (!temp) return AVERROR(ENOMEM); for (i = 0; i <= n / 2; i++) { tmp = alpha2 * i * (n - i); temp[i] = av_bessel_i0(sqrt(tmp)); scale += temp[i] * (1 + (i && i<n/2)); } scale = 1.0/(scale + 1); for (i = 0; i <= n / 2; i++) { sum += temp[i]; if (float_window) float_window[i] = sqrt(sum * scale); else int_window[i] = lrint(2147483647 * sqrt(sum * scale)); } for (; i < n; i++) { sum += temp[n - i]; if (float_window) float_window[i] = sqrt(sum * scale); else int_window[i] = lrint(2147483647 * sqrt(sum * scale)); } if (temp != temp_small) av_free(temp); return 0; } av_cold int avpriv_kbd_window_init(float *window, float alpha, int n) { return kbd_window_init(window, NULL, alpha, n); } av_cold int avpriv_kbd_window_init_fixed(int32_t *window, float alpha, int n) { return kbd_window_init(NULL, window, alpha, n); }