+int av_reduce(int *dst_num, int *dst_den, int64_t num, int64_t den, int64_t max);
+
+/**
+ * Multiply two rationals.
+ * @param b first rational
+ * @param c second rational
+ * @return b*c
+ */
+AVRational av_mul_q(AVRational b, AVRational c) av_const;
+
+/**
+ * Divide one rational by another.
+ * @param b first rational
+ * @param c second rational
+ * @return b/c
+ */
+AVRational av_div_q(AVRational b, AVRational c) av_const;
+
+/**
+ * Add two rationals.
+ * @param b first rational
+ * @param c second rational
+ * @return b+c
+ */
+AVRational av_add_q(AVRational b, AVRational c) av_const;
+
+/**
+ * Subtract one rational from another.
+ * @param b first rational
+ * @param c second rational
+ * @return b-c
+ */
+AVRational av_sub_q(AVRational b, AVRational c) av_const;
+
+/**
+ * Invert a rational.
+ * @param q value
+ * @return 1 / q
+ */
+static av_always_inline AVRational av_inv_q(AVRational q)
+{
+ AVRational r = { q.den, q.num };
+ return r;
+}
+
+/**
+ * Convert a double precision floating point number to a rational.
+ * inf is expressed as {1,0} or {-1,0} depending on the sign.
+ *
+ * @param d double to convert
+ * @param max the maximum allowed numerator and denominator
+ * @return (AVRational) d
+ */
+AVRational av_d2q(double d, int max) av_const;