EXFO EXpert IPTV Test Tools (FTB-200v2) - Manual (Page 71)

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A.5 IGMP Latency vs. Zap time
The zap time is the total duration from the time viewer presses the channel change
button, to the point the picture of the new channel is displayed, along with corresponding
audio. These kind of delays exist in all
television systems, but they are greater in digital
television and systems that use the Internet like IPTV . Human interaction with the system is
completely ignored in these measurements, so zap time is not the same as channel surfing .
Key Factors affecting Zap Time
 Encoding
 Network
 Set top Box (leave and joins)