I agree with John Denker that encoding is (or ought to be) more time
consuming than decoding. But that is inconsistent with what people are
observing when different cable boxes and TVs in the same house are
putting the same channel on the screen at times differing by a couple
seconds. That data would suggest one of the cable boxes is the slow
link, or one of the TVs is the slow link.
I also notice that after I converted to HD-digital (after having had
analog), the time to change channels increased from essentially nothing
to a couple seconds. Of course either the cable box or TV (depending on
how they're set up) has to decide if the broadcast is 480p, 780i, 780p,
or 1080i and make that switch. How long does that take?
In my case, my Sony XBR4 TV can do 1080p and supposedly does a good job
of dealing with different resolutions, so I have my cable box set to
give the TV the same format as the broadcast, so any screen formatting
takes place in the TV rather than the cable box. Anyway, when I switch
from one channel to the next, even if the resolution does not change,
there is approximately a 2-second delay with a black screen before the
new channel comes up.
What's causing this channel switching delay if the decoding process is
the fast process (and encoding is the slow process)? And, what's causing
two TVs in the same house to be out of synchronization if they are both
HD-digital viewing the same station, but with different cable boxes
and/or different TVs?
Michael D. Edmiston, Ph.D.
Professor of Chemistry and Physics
Bluffton University
Bluffton, OH 45817
(419)-358-3270
edmiston@bluffton.edu