以下是源代码位置，你可以看注释体会
// if we STILL don't prefer one detection over the other, then pick
// any deterministic criterion.
for (int i = 0; i < 4; i++) {
pref = prefer_smaller(pref, det0->p[i][0], det1->p[i][0]);
pref = prefer_smaller(pref, det0->p[i][1], det1->p[i][1]);
}
if (pref == 0) {
// at this point, we should only be undecided if the tag detections
// are *exactly* the same. How would that happen?
mp_printf(&mp_plat_print, "uh oh, no preference for overlappingdetection\n");
}
