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Diffstat (limited to 'media/ffvpx/libavutil/rational.c')
| -rw-r--r-- | media/ffvpx/libavutil/rational.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/media/ffvpx/libavutil/rational.c b/media/ffvpx/libavutil/rational.c new file mode 100644 index 000000000..35ee08877 --- /dev/null +++ b/media/ffvpx/libavutil/rational.c @@ -0,0 +1,184 @@ +/* + * rational numbers + * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at> + * + * 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 + */ + +/** + * @file + * rational numbers + * @author Michael Niedermayer <michaelni@gmx.at> + */ + +#include "avassert.h" +#include <limits.h> + +#include "common.h" +#include "mathematics.h" +#include "rational.h" + +int av_reduce(int *dst_num, int *dst_den, + int64_t num, int64_t den, int64_t max) +{ + AVRational a0 = { 0, 1 }, a1 = { 1, 0 }; + int sign = (num < 0) ^ (den < 0); + int64_t gcd = av_gcd(FFABS(num), FFABS(den)); + + if (gcd) { + num = FFABS(num) / gcd; + den = FFABS(den) / gcd; + } + if (num <= max && den <= max) { + a1 = (AVRational) { num, den }; + den = 0; + } + + while (den) { + uint64_t x = num / den; + int64_t next_den = num - den * x; + int64_t a2n = x * a1.num + a0.num; + int64_t a2d = x * a1.den + a0.den; + + if (a2n > max || a2d > max) { + if (a1.num) x = (max - a0.num) / a1.num; + if (a1.den) x = FFMIN(x, (max - a0.den) / a1.den); + + if (den * (2 * x * a1.den + a0.den) > num * a1.den) + a1 = (AVRational) { x * a1.num + a0.num, x * a1.den + a0.den }; + break; + } + + a0 = a1; + a1 = (AVRational) { a2n, a2d }; + num = den; + den = next_den; + } + av_assert2(av_gcd(a1.num, a1.den) <= 1U); + av_assert2(a1.num <= max && a1.den <= max); + + *dst_num = sign ? -a1.num : a1.num; + *dst_den = a1.den; + + return den == 0; +} + +AVRational av_mul_q(AVRational b, AVRational c) +{ + av_reduce(&b.num, &b.den, + b.num * (int64_t) c.num, + b.den * (int64_t) c.den, INT_MAX); + return b; +} + +AVRational av_div_q(AVRational b, AVRational c) +{ + return av_mul_q(b, (AVRational) { c.den, c.num }); +} + +AVRational av_add_q(AVRational b, AVRational c) { + av_reduce(&b.num, &b.den, + b.num * (int64_t) c.den + + c.num * (int64_t) b.den, + b.den * (int64_t) c.den, INT_MAX); + return b; +} + +AVRational av_sub_q(AVRational b, AVRational c) +{ + return av_add_q(b, (AVRational) { -c.num, c.den }); +} + +AVRational av_d2q(double d, int max) +{ + AVRational a; + int exponent; + int64_t den; + if (isnan(d)) + return (AVRational) { 0,0 }; + if (fabs(d) > INT_MAX + 3LL) + return (AVRational) { d < 0 ? -1 : 1, 0 }; + frexp(d, &exponent); + exponent = FFMAX(exponent-1, 0); + den = 1LL << (61 - exponent); + // (int64_t)rint() and llrint() do not work with gcc on ia64 and sparc64, + // see Ticket2713 for affected gcc/glibc versions + av_reduce(&a.num, &a.den, floor(d * den + 0.5), den, max); + if ((!a.num || !a.den) && d && max>0 && max<INT_MAX) + av_reduce(&a.num, &a.den, floor(d * den + 0.5), den, INT_MAX); + + return a; +} + +int av_nearer_q(AVRational q, AVRational q1, AVRational q2) +{ + /* n/d is q, a/b is the median between q1 and q2 */ + int64_t a = q1.num * (int64_t)q2.den + q2.num * (int64_t)q1.den; + int64_t b = 2 * (int64_t)q1.den * q2.den; + + /* rnd_up(a*d/b) > n => a*d/b > n */ + int64_t x_up = av_rescale_rnd(a, q.den, b, AV_ROUND_UP); + + /* rnd_down(a*d/b) < n => a*d/b < n */ + int64_t x_down = av_rescale_rnd(a, q.den, b, AV_ROUND_DOWN); + + return ((x_up > q.num) - (x_down < q.num)) * av_cmp_q(q2, q1); +} + +int av_find_nearest_q_idx(AVRational q, const AVRational* q_list) +{ + int i, nearest_q_idx = 0; + for (i = 0; q_list[i].den; i++) + if (av_nearer_q(q, q_list[i], q_list[nearest_q_idx]) > 0) + nearest_q_idx = i; + + return nearest_q_idx; +} + +uint32_t av_q2intfloat(AVRational q) { + int64_t n; + int shift; + int sign = 0; + + if (q.den < 0) { + q.den *= -1; + q.num *= -1; + } + if (q.num < 0) { + q.num *= -1; + sign = 1; + } + + if (!q.num && !q.den) return 0xFFC00000; + if (!q.num) return 0; + if (!q.den) return 0x7F800000 | (q.num & 0x80000000); + + shift = 23 + av_log2(q.den) - av_log2(q.num); + if (shift >= 0) n = av_rescale(q.num, 1LL<<shift, q.den); + else n = av_rescale(q.num, 1, ((int64_t)q.den) << -shift); + + shift -= n >= (1<<24); + shift += n < (1<<23); + + if (shift >= 0) n = av_rescale(q.num, 1LL<<shift, q.den); + else n = av_rescale(q.num, 1, ((int64_t)q.den) << -shift); + + av_assert1(n < (1<<24)); + av_assert1(n >= (1<<23)); + + return sign<<31 | (150-shift)<<23 | (n - (1<<23)); +} |