diff options
Diffstat (limited to 'libavutil/mathematics.c')
| -rw-r--r-- | libavutil/mathematics.c | 120 |
1 files changed, 105 insertions, 15 deletions
diff --git a/libavutil/mathematics.c b/libavutil/mathematics.c index 617726d897..1bf044cdf1 100644 --- a/libavutil/mathematics.c +++ b/libavutil/mathematics.c @@ -1,20 +1,20 @@ /* - * Copyright (c) 2005 Michael Niedermayer <michaelni@gmx.at> + * Copyright (c) 2005-2012 Michael Niedermayer <michaelni@gmx.at> * - * This file is part of Libav. + * This file is part of FFmpeg. * - * Libav is free software; you can redistribute it and/or + * 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. * - * Libav is distributed in the hope that it will be useful, + * 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 Libav; if not, write to the Free Software + * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ @@ -27,25 +27,52 @@ #include <limits.h> #include "mathematics.h" +#include "libavutil/intmath.h" +#include "libavutil/common.h" +#include "avassert.h" #include "version.h" -int64_t av_gcd(int64_t a, int64_t b) -{ - if (b) - return av_gcd(b, a % b); - else +/* Stein's binary GCD algorithm: + * https://en.wikipedia.org/wiki/Binary_GCD_algorithm */ +int64_t av_gcd(int64_t a, int64_t b) { + int za, zb, k; + int64_t u, v; + if (a == 0) + return b; + if (b == 0) return a; + za = ff_ctzll(a); + zb = ff_ctzll(b); + k = FFMIN(za, zb); + u = llabs(a >> za); + v = llabs(b >> zb); + while (u != v) { + if (u > v) + FFSWAP(int64_t, v, u); + v -= u; + v >>= ff_ctzll(v); + } + return (uint64_t)u << k; } int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding rnd) { int64_t r = 0; + av_assert2(c > 0); + av_assert2(b >=0); + av_assert2((unsigned)(rnd&~AV_ROUND_PASS_MINMAX)<=5 && (rnd&~AV_ROUND_PASS_MINMAX)!=4); - if (c <= 0 || b < 0 || rnd == 4 || rnd > 5) + if (c <= 0 || b < 0 || !((unsigned)(rnd&~AV_ROUND_PASS_MINMAX)<=5 && (rnd&~AV_ROUND_PASS_MINMAX)!=4)) return INT64_MIN; - if (a < 0 && a != INT64_MIN) - return -av_rescale_rnd(-a, b, c, rnd ^ ((rnd >> 1) & 1)); + if (rnd & AV_ROUND_PASS_MINMAX) { + if (a == INT64_MIN || a == INT64_MAX) + return a; + rnd -= AV_ROUND_PASS_MINMAX; + } + + if (a < 0) + return -(uint64_t)av_rescale_rnd(-FFMAX(a, -INT64_MAX), b, c, rnd ^ ((rnd >> 1) & 1)); if (rnd == AV_ROUND_NEAR_INF) r = c / 2; @@ -55,9 +82,15 @@ int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding rnd) if (b <= INT_MAX && c <= INT_MAX) { if (a <= INT_MAX) return (a * b + r) / c; - else - return a / c * b + (a % c * b + r) / c; + else { + int64_t ad = a / c; + int64_t a2 = (a % c * b + r) / c; + if (ad >= INT32_MAX && b && ad > (INT64_MAX - a2) / b) + return INT64_MIN; + return ad * b + a2; + } } else { +#if 1 uint64_t a0 = a & 0xFFFFFFFF; uint64_t a1 = a >> 32; uint64_t b0 = b & 0xFFFFFFFF; @@ -79,7 +112,17 @@ int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding rnd) t1++; } } + if (t1 > INT64_MAX) + return INT64_MIN; return t1; +#else + /* reference code doing (a*b + r) / c, requires libavutil/integer.h */ + AVInteger ai; + ai = av_mul_i(av_int2i(a), av_int2i(b)); + ai = av_add_i(ai, av_int2i(r)); + + return av_i2int(av_div_i(ai, av_int2i(c))); +#endif } } @@ -105,6 +148,8 @@ int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b) { int64_t a = tb_a.num * (int64_t)tb_b.den; int64_t b = tb_b.num * (int64_t)tb_a.den; + if ((FFABS(ts_a)|a|FFABS(ts_b)|b) <= INT_MAX) + return (ts_a*a > ts_b*b) - (ts_a*a < ts_b*b); if (av_rescale_rnd(ts_a, a, b, AV_ROUND_DOWN) < ts_b) return -1; if (av_rescale_rnd(ts_b, b, a, AV_ROUND_DOWN) < ts_a) @@ -119,3 +164,48 @@ int64_t av_compare_mod(uint64_t a, uint64_t b, uint64_t mod) c -= mod; return c; } + +int64_t av_rescale_delta(AVRational in_tb, int64_t in_ts, AVRational fs_tb, int duration, int64_t *last, AVRational out_tb){ + int64_t a, b, this; + + av_assert0(in_ts != AV_NOPTS_VALUE); + av_assert0(duration >= 0); + + if (*last == AV_NOPTS_VALUE || !duration || in_tb.num*(int64_t)out_tb.den <= out_tb.num*(int64_t)in_tb.den) { +simple_round: + *last = av_rescale_q(in_ts, in_tb, fs_tb) + duration; + return av_rescale_q(in_ts, in_tb, out_tb); + } + + a = av_rescale_q_rnd(2*in_ts-1, in_tb, fs_tb, AV_ROUND_DOWN) >>1; + b = (av_rescale_q_rnd(2*in_ts+1, in_tb, fs_tb, AV_ROUND_UP )+1)>>1; + if (*last < 2*a - b || *last > 2*b - a) + goto simple_round; + + this = av_clip64(*last, a, b); + *last = this + duration; + + return av_rescale_q(this, fs_tb, out_tb); +} + +int64_t av_add_stable(AVRational ts_tb, int64_t ts, AVRational inc_tb, int64_t inc) +{ + int64_t m, d; + + if (inc != 1) + inc_tb = av_mul_q(inc_tb, (AVRational) {inc, 1}); + + m = inc_tb.num * (int64_t)ts_tb.den; + d = inc_tb.den * (int64_t)ts_tb.num; + + if (m % d == 0) + return ts + m / d; + if (m < d) + return ts; + + { + int64_t old = av_rescale_q(ts, ts_tb, inc_tb); + int64_t old_ts = av_rescale_q(old, inc_tb, ts_tb); + return av_rescale_q(old + 1, inc_tb, ts_tb) + (ts - old_ts); + } +} |