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