Exfo EXpert IPTV Test Tools (FTB-200v2) Instrukcja Użytkownika Pobierz pdf (Strona 73)

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ThejoinmessageasksthenetworktosendtherequestedprogramorchanneltotheSTBby

joiningamulticastgroupcarryingthedesiredbroadcastchannel.

IGMPlatency,then,isthetimebetweenwhenthejoinmessageissentandthefirstvideo

packetisreceivedbytheSTB.

Thisparame

termeasuresnetworkperformance,butnottheenduser'sexperiencewith

regardtochannelchangingtime.

TheIGMPlatencyplusthetimeittakestofillthedecodebufferandtodecodeanddisplaythe

contentisthetotaluserexperiencetime.However,thebufferfilltimeandthedecodetime

arefuncti

onsofthenetworkarchitectureandarenotvariables.ThistotaltimeiscalledZap

Time.

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Exfo EXpert IPTV Test Tools (FTB-200v2) Instrukcja Użytkownika Strona 73