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.
Zap time can be very disturbing for the viewer since it has to wait too much time when decides to switch the channel. For this reason, zap time is an IPTV feature that has to be reduced in an IPTV system.
... In this section some typical values of zap time are shown ... Actually, in IPTV television these delays are greater than in other technologies Analog (Cable) ~ 1s Analog (off-air) ~ 1 – 3s MPEG2 over QAM ~ 1.2 – 3s MPEG2 over QPSK ~ 2 – 4s MPEG2 over IP Multicast ~ 1.5 – 3.5s H.264 over IP Multicast ~ 1.7 – 4s ...
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