+
+int64_t av_rescale_delta(AVRational in_tb, int64_t in_ts, AVRational fs_tb, int duration, int64_t *last, AVRational out_tb){
+ int64_t a, b, this;
+
+ av_assert0(in_ts != AV_NOPTS_VALUE);
+ av_assert0(duration >= 0);
+
+ if (*last == AV_NOPTS_VALUE || !duration || in_tb.num*(int64_t)out_tb.den <= out_tb.num*(int64_t)in_tb.den) {
+simple_round:
+ *last = av_rescale_q(in_ts, in_tb, fs_tb) + duration;
+ return av_rescale_q(in_ts, in_tb, out_tb);
+ }
+
+ a = av_rescale_q_rnd(2*in_ts-1, in_tb, fs_tb, AV_ROUND_DOWN) >>1;
+ b = (av_rescale_q_rnd(2*in_ts+1, in_tb, fs_tb, AV_ROUND_UP )+1)>>1;
+ if (*last < 2*a - b || *last > 2*b - a)
+ goto simple_round;
+
+ this = av_clip64(*last, a, b);
+ *last = this + duration;
+
+ return av_rescale_q(this, fs_tb, out_tb);
+}