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