compute_metric    603 libavfilter/vf_pullup.c     compute_metric(s, f->diffs, f, parity, f->prev->prev, parity, s->diff);
compute_metric    604 libavfilter/vf_pullup.c     compute_metric(s, f->combs, parity ? f->prev : f, 0, parity ? f : f->prev, 1, s->comb);
compute_metric    605 libavfilter/vf_pullup.c     compute_metric(s, f->vars, f, parity, f, -1, s->var);