av_compare_ts()

Originally committed as revision 21671 to svn://svn.ffmpeg.org/ffmpeg/trunk

2 files changed, 17 insertions, 0 deletions

diff --git a/libavutil/mathematics.c b/libavutil/mathematics.c
index 9988baae9c..91b76f3aaf 100644
--- a/libavutil/mathematics.c
+++ b/libavutil/mathematics.c
@@ -136,6 +136,14 @@ int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq){
     return av_rescale_rnd(a, b, c, AV_ROUND_NEAR_INF);
 }
 
+int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b){
+    int64_t a= tb_a.num * (int64_t)tb_b.den;
+    int64_t b= tb_b.num * (int64_t)tb_a.den;
+    if (av_rescale_rnd(ts_a, a, b, AV_ROUND_DOWN) < ts_b) return -1;
+    if (av_rescale_rnd(ts_b, b, a, AV_ROUND_DOWN) < ts_a) return  1;
+    return 0;
+}
+
 #ifdef TEST
 #include "integer.h"
 #undef printf
diff --git a/libavutil/mathematics.h b/libavutil/mathematics.h
index 12cd369036..29b13f77ed 100644
--- a/libavutil/mathematics.h
+++ b/libavutil/mathematics.h
@@ -80,4 +80,13 @@ int64_t av_rescale_rnd(int64_t a, int64_t b, int64_t c, enum AVRounding) av_cons
  */
 int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq) av_const;
 
+/**
+ * Compares 2 timestamps each in its own timebases.
+ * The result of the function is undefined if one of the timestamps
+ * is outside the int64_t range when represented in the others timebase.
+ * @returns -1 if ts_a is before ts_b, 1 if ts_a is after ts_b or 0 if they represent the same position
+ */
+int av_compare_ts(int64_t ts_a, AVRational tb_a, int64_t ts_b, AVRational tb_b);
+
+
 #endif /* AVUTIL_MATHEMATICS_H */