From e9add0d85b38db8efebd53bed83125945103e11f Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Mon, 2 Jun 2014 19:00:18 +0200
Subject: [PATCH] av_add_stable: Add fast special case where step can be
represented exactly
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
---
libavutil/mathematics.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/libavutil/mathematics.c b/libavutil/mathematics.c
index c8f1e1cd897..df7d0d88bf3 100644
--- a/libavutil/mathematics.c
+++ b/libavutil/mathematics.c
@@ -188,9 +188,17 @@ simple_round:
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 (av_cmp_q(inc_tb, ts_tb) < 0) {
//increase step is too small for even 1 step to be representable
return ts;
--
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