int64_t vframes() { return images.size(); }
void reset() { seq_no = 0; cycle_start = 0; age = 0; }
+ void reset(double rate) { reset(); frame_rate = rate; }
void clear_images() { images.remove_all_objects(); }
virtual int64_t set_seq_no(int64_t no) { return seq_no = no; }