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Implement av_nearer_q() and av_find_nearest_q_idx() functions.
Originally committed as revision 15415 to svn://svn.ffmpeg.org/ffmpeg/trunk
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@ -35,7 +35,7 @@
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#define AV_VERSION(a, b, c) AV_VERSION_DOT(a, b, c)
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#define LIBAVUTIL_VERSION_MAJOR 49
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#define LIBAVUTIL_VERSION_MINOR 10
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#define LIBAVUTIL_VERSION_MINOR 11
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#define LIBAVUTIL_VERSION_MICRO 0
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#define LIBAVUTIL_VERSION_INT AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
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@ -101,3 +101,28 @@ AVRational av_d2q(double d, int max){
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return a;
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}
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int av_nearer_q(AVRational q, AVRational q1, AVRational q2)
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{
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/* n/d is q, a/b is the median between q1 and q2 */
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int64_t a = q1.num * (int64_t)q2.den + q2.num * (int64_t)q1.den;
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int64_t b = 2 * (int64_t)q1.den * q2.den;
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/* rnd_up(a*d/b) > n => a*d/b > n */
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int64_t x_up = av_rescale_rnd(a, q.den, b, AV_ROUND_UP);
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/* rnd_down(a*d/b) < n => a*d/b < n */
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int64_t x_down = av_rescale_rnd(a, q.den, b, AV_ROUND_DOWN);
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return ((x_up > q.num) - (x_down < q.num)) * av_cmp_q(q2, q1);
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}
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int av_find_nearest_q_idx(AVRational q, const AVRational* q_list)
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{
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int i, nearest_q_idx = 0;
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for(i=0; q_list[i].den; i++)
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if (av_nearer_q(q, q_list[i], q_list[nearest_q_idx]) > 0)
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nearest_q_idx = i;
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return nearest_q_idx;
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}
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@ -113,4 +113,17 @@ AVRational av_sub_q(AVRational b, AVRational c) av_const;
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*/
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AVRational av_d2q(double d, int max) av_const;
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/**
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* @return 1 if \q1 is nearer to \p q than \p q2, -1 if \p q2 is nearer
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* than \p q1, 0 if they have the same distance.
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*/
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int av_nearer_q(AVRational q, AVRational q1, AVRational q2);
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/**
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* Finds the nearest value in \p q_list to \p q.
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* @param q_list an array of rationals terminated by {0, 0}
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* @return the index of the nearest value found in the array
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*/
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int av_find_nearest_q_idx(AVRational q, const AVRational* q_list);
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#endif /* AVUTIL_RATIONAL_H */
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