mirror of https://github.com/FFmpeg/FFmpeg.git
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
103 lines
2.9 KiB
103 lines
2.9 KiB
/* |
|
* 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; |
|
} |
|
}
|
|
|