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103 lines
2.9 KiB
103 lines
2.9 KiB
/* |
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* This file is part of Libav. |
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* |
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* Libav 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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* Libav 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 Libav; 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/rational.h" |
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#include "mpeg12.h" |
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#include "mpeg12data.h" |
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const AVRational ff_mpeg12_frame_rate_tab[16] = { |
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{ 0, 0}, |
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{24000, 1001}, |
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{ 24, 1}, |
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{ 25, 1}, |
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{30000, 1001}, |
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{ 30, 1}, |
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{ 50, 1}, |
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{60000, 1001}, |
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{ 60, 1}, |
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// Xing's 15fps: (9) |
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{ 15, 1}, |
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// libmpeg3's "Unofficial economy rates": (10-13) |
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{ 5, 1}, |
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{ 10, 1}, |
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{ 12, 1}, |
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{ 15, 1}, |
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{ 0, 0}, |
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}; |
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void ff_mpeg12_find_best_frame_rate(AVRational frame_rate, |
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int *code, int *ext_n, int *ext_d, |
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int nonstandard) |
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{ |
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int mpeg2 = ext_n && ext_d; |
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int max_code = nonstandard ? 12 : 8; |
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int c, n, d, best_c, best_n, best_d; |
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AVRational best_error = { INT_MAX, 1 }; |
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// Default to NTSC if the inputs make no sense. |
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best_c = 4; |
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best_n = best_d = 1; |
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for (c = 1; c <= max_code; c++) { |
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if (av_cmp_q(frame_rate, ff_mpeg12_frame_rate_tab[c]) == 0) { |
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best_c = c; |
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goto found; |
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} |
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} |
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for (c = 1; c <= max_code; c++) { |
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for (n = 1; n <= (mpeg2 ? 4 : 1); n++) { |
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for (d = 1; d <= (mpeg2 ? 32 : 1); d++) { |
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AVRational test, error; |
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int cmp; |
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test = av_mul_q(ff_mpeg12_frame_rate_tab[c], |
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(AVRational) { n, d }); |
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cmp = av_cmp_q(test, frame_rate); |
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if (cmp == 0) { |
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best_c = c; |
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best_n = n; |
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best_d = d; |
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goto found; |
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} |
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if (cmp < 0) |
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error = av_div_q(frame_rate, test); |
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else |
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error = av_div_q(test, frame_rate); |
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cmp = av_cmp_q(error, best_error); |
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if (cmp < 0 || (cmp == 0 && n == 1 && d == 1)) { |
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best_c = c; |
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best_n = n; |
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best_d = d; |
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best_error = error; |
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} |
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} |
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} |
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} |
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found: |
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*code = best_c; |
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if (mpeg2) { |
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*ext_n = best_n - 1; |
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*ext_d = best_d - 1; |
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} |
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}
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