mirror of
https://github.com/FFmpeg/FFmpeg.git
synced 2024-12-02 03:06:28 +02:00
278c308cea
This will be used later in both the mpeg2_metadata filter and the
VAAPI MPEG-2 encoder. Also adds a unit test.
(cherry picked from commit b5859e0b04)
104 lines
2.9 KiB
C
104 lines
2.9 KiB
C
/*
|
|
* 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;
|
|
}
|
|
}
|