X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=libavutil%2Frational.c;h=097519ccbe03af858e0d9ee8a416ddec038fd184;hb=702d0a9e85912961d66c62bc2e019ba3290ce78d;hp=1924c687d019da92b5c7414116c87e2e221a6ac2;hpb=b78e7197a81e193827cf2408fe25bc1f14843a72;p=ffmpeg

diff --git a/libavutil/rational.c b/libavutil/rational.c
index 1924c687d01..097519ccbe0 100644
--- a/libavutil/rational.c
+++ b/libavutil/rational.c
@@ -1,5 +1,5 @@
 /*
- * Rational numbers
+ * rational numbers
  * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
  *
  * This file is part of FFmpeg.
@@ -17,15 +17,15 @@
  * 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.c
- * Rational numbers
+ * @file libavutil/rational.c
+ * rational numbers
  * @author Michael Niedermayer <michaelni@gmx.at>
  */
 
+#include <assert.h>
 //#include <math.h>
 #include <limits.h>
 
@@ -33,73 +33,66 @@
 #include "mathematics.h"
 #include "rational.h"
 
-int av_reduce(int *dst_nom, int *dst_den, int64_t nom, int64_t den, int64_t max){
+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= (nom<0) ^ (den<0);
-    int64_t gcd= ff_gcd(ABS(nom), ABS(den));
+    int sign= (num<0) ^ (den<0);
+    int64_t gcd= av_gcd(FFABS(num), FFABS(den));
 
-    nom = ABS(nom)/gcd;
-    den = ABS(den)/gcd;
-    if(nom<=max && den<=max){
-        a1= (AVRational){nom, den};
+    if(gcd){
+        num = FFABS(num)/gcd;
+        den = FFABS(den)/gcd;
+    }
+    if(num<=max && den<=max){
+        a1= (AVRational){num, den};
         den=0;
     }
 
     while(den){
-        int64_t x       = nom / den;
-        int64_t next_den= nom - den*x;
+        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) break;
+        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};
-        nom= den;
+        num= den;
         den= next_den;
     }
-    assert(ff_gcd(a1.num, a1.den) == 1);
+    assert(av_gcd(a1.num, a1.den) <= 1U);
 
-    *dst_nom = sign ? -a1.num : a1.num;
+    *dst_num = sign ? -a1.num : a1.num;
     *dst_den = a1.den;
 
     return den==0;
 }
 
-/**
- * returns b*c.
- */
 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;
 }
 
-/**
- * returns b/c.
- */
 AVRational av_div_q(AVRational b, AVRational c){
     return av_mul_q(b, (AVRational){c.den, c.num});
 }
 
-/**
- * returns b+c.
- */
 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;
 }
 
-/**
- * returns b-c.
- */
 AVRational av_sub_q(AVRational b, AVRational c){
     return av_add_q(b, (AVRational){-c.num, c.den});
 }
 
-/**
- * Converts a double precission floating point number to a AVRational.
- * @param max the maximum allowed numerator and denominator
- */
 AVRational av_d2q(double d, int max){
     AVRational a;
 #define LOG2  0.69314718055994530941723212145817656807550013436025
@@ -109,3 +102,28 @@ 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;
+}