From 05b90fc0c59aaac40af484f3d5a617a0404b1b4e Mon Sep 17 00:00:00 2001 From: Stefano Sabatini Date: Thu, 25 Sep 2008 19:23:13 +0000 Subject: [PATCH] Implement av_nearer_q() and av_find_nearest_q_idx() functions. Originally committed as revision 15415 to svn://svn.ffmpeg.org/ffmpeg/trunk --- libavutil/avutil.h | 2 +- libavutil/rational.c | 25 +++++++++++++++++++++++++ libavutil/rational.h | 13 +++++++++++++ 3 files changed, 39 insertions(+), 1 deletion(-) diff --git a/libavutil/avutil.h b/libavutil/avutil.h index 03c5520d9b..801eb51d90 100644 --- a/libavutil/avutil.h +++ b/libavutil/avutil.h @@ -35,7 +35,7 @@ #define AV_VERSION(a, b, c) AV_VERSION_DOT(a, b, c) #define LIBAVUTIL_VERSION_MAJOR 49 -#define LIBAVUTIL_VERSION_MINOR 10 +#define LIBAVUTIL_VERSION_MINOR 11 #define LIBAVUTIL_VERSION_MICRO 0 #define LIBAVUTIL_VERSION_INT AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \ diff --git a/libavutil/rational.c b/libavutil/rational.c index 96a4c5462e..cac3ff5a99 100644 --- a/libavutil/rational.c +++ b/libavutil/rational.c @@ -101,3 +101,28 @@ AVRational av_d2q(double d, 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; +} diff --git a/libavutil/rational.h b/libavutil/rational.h index 5957eee859..70b7735da3 100644 --- a/libavutil/rational.h +++ b/libavutil/rational.h @@ -113,4 +113,17 @@ AVRational av_sub_q(AVRational b, AVRational c) av_const; */ AVRational av_d2q(double d, int max) av_const; +/** + * @return 1 if \q1 is nearer to \p q than \p q2, -1 if \p q2 is nearer + * than \p q1, 0 if they have the same distance. + */ +int av_nearer_q(AVRational q, AVRational q1, AVRational q2); + +/** + * Finds the nearest value in \p q_list to \p q. + * @param q_list an array of rationals terminated by {0, 0} + * @return the index of the nearest value found in the array + */ +int av_find_nearest_q_idx(AVRational q, const AVRational* q_list); + #endif /* AVUTIL_RATIONAL_H */