+//FIXME calculate exactly, this is just a good approximation.
+static int64_t find_duration(NUTContext *nut, int64_t filesize)
+{
+ AVFormatContext *s = nut->avf;
+ int64_t duration = 0;
+
+ int64_t pos = FFMAX(0, filesize - 2*nut->max_distance);
+ for(;;){
+ int64_t ts = nut_read_timestamp(s, -1, &pos, INT64_MAX);
+ if(ts < 0)
+ break;
+ duration = FFMAX(duration, ts);
+ pos++;
+ }
+ if(duration > 0)
+ s->duration_estimation_method = AVFMT_DURATION_FROM_PTS;
+ return duration;
+}
+