/*

 * 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;

    }

}