Make sure av_set_pts_info() does not set the fields of a timebase to

negative values.

Originally committed as revision 19325 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/utils.c

@@ -3306,11 +3306,11 @@ char *ff_data_to_hex(char *buff, const uint8_t *src, int s)
 void av_set_pts_info(AVStream *s, int pts_wrap_bits,
                      unsigned int pts_num, unsigned int pts_den)
 {
-    unsigned int gcd= av_gcd(pts_num, pts_den);
     s->pts_wrap_bits = pts_wrap_bits;
-    s->time_base.num = pts_num/gcd;
-    s->time_base.den = pts_den/gcd;
 
-    if(gcd>1)
-        av_log(NULL, AV_LOG_DEBUG, "st:%d removing common factor %d from timebase\n", s->index, gcd);
+    if(av_reduce(&s->time_base.num, &s->time_base.den, pts_num, pts_den, INT_MAX)){
+        if(s->time_base.num != pts_num)
+            av_log(NULL, AV_LOG_DEBUG, "st:%d removing common factor %d from timebase\n", s->index, pts_num/s->time_base.num);
+    }else
+        av_log(NULL, AV_LOG_WARNING, "st:%d has too large timebase, reducing\n", s->index);
 }