▁these ▁formats . ▁A ▁similar ▁standard ▁exists ▁in ▁countries ▁using ▁the ▁N T SC ▁system , ▁though ▁with ▁no ▁requirement ▁mand ating ▁the ▁use ▁of ▁or ▁support ▁for ▁the ▁MP 2 ▁format . ▁D TS ▁audio ▁is ▁optional ▁for ▁all ▁players , ▁as ▁D TS ▁was ▁not ▁part ▁of ▁the ▁initial ▁draft ▁standard ▁and ▁was ▁added ▁later ; ▁thus , ▁many ▁early ▁players ▁are ▁unable ▁to ▁play ▁D TS ▁audio ▁tracks . ▁Only ▁PC M ▁and ▁D TS ▁support ▁ 9 6   k Hz ▁sampling ▁rate . ▁Because ▁PC M , ▁being ▁un com pressed , ▁requires ▁a ▁lot ▁of ▁band width ▁and ▁D TS ▁is ▁not ▁univers ally ▁supported ▁by ▁players , ▁AC - 3 ▁is ▁the ▁most ▁common ▁digital ▁audio ▁format ▁for ▁DVD s , ▁and ▁ 9 6   k Hz ▁is ▁rare ▁on ▁a ▁DVD . ▁The ▁official ▁allowed ▁formats ▁for ▁the ▁audio ▁tracks ▁on ▁a ▁DVD - Video ▁are : ▁ ▁PC M : ▁ 4 8   k Hz ▁or ▁ 9 6   k Hz ▁sampling ▁rate , ▁ 1 6 ▁bit ▁or ▁ 2 4 ▁bit ▁Linear ▁PC M , ▁ 2 ▁to ▁ 6 ▁channels , ▁up ▁to ▁ 6 , 1 4 4 ▁k bit / s ; ▁N . ▁B . ▁ 1 6 - bit ▁ 4 8   k Hz ▁ 8 ▁channel ▁PC M ▁is ▁allowed ▁by ▁the ▁DVD - Video ▁specification ▁but ▁is ▁not ▁well - supported ▁by ▁author ing ▁applications ▁or ▁players ; ▁ ▁AC -