文档介绍：:0 12 3012345678901234567890**********PTsequencenumbertimestamp+—4—+—+—+—+—+—4—+—+—+—+—+—+—+—+—+—+—+—+—+—+—+—+—+—+—+—+—4—+—+—+—+synchronizationsource(SSRC)identifiercontributin£source(CSRC)identifiersThefirsttwelveoctetsarepresentineveryRTPpacket,:version(V):(2).(Thevalue1isusedbythefirstdraftversionofRTPandthevalue0isusedbytheprotocolinitiallyimplementedinthe audiotool.)padding(P):1bitTfthepaddingbitisset,thepacketcontainsoneormoreadditionalpaddingoctetsattheendwhicharenotpartofthepayload・Thelastoctetofthepaddingcontainsacountofhowmanypaddingoctetsshouldbeignored,ineludingitsclf・PaddingmaybeneededbysomeencryptionalgorithmswithfixedblocksizesorforcarryingseveralRTPpacketsinalower-(X):1bitIftheextensionbitisset,thefixedheaderMUSTbefollowedbyexactlyoneheaderextension,.):(M):