V_hd_qthresh
if (qdly < V_hd_qthresh) {
(V_hd_qthresh - V_hd_qmin)) * (qdly - V_hd_qmin);
if (qdly > V_hd_qthresh)
(maxqdly - V_hd_qthresh)) * (maxqdly - qdly);
if (e_t->rtt && e_t->minrtt && V_hd_qthresh > 0) {
if (new > V_hd_qthresh)
new = V_hd_qthresh;
V_hd_qthresh = new;