Page 126 - TELE-audiovision - The World’s Largest Digital TV Trade Magazine

10
11
12
126 TELE-audiovision International — The World‘s Largest Digital TV Trade Magazine — 05-06/2013 — TELE-audiovision.com
is served; a single tuner
couldn’t even process chan-
nels from different tran-
sponders at the same time
anyway.
The solution is multiple
tuner server boxes so that,
for example, the four levels
of a satellite position can
be received independently
from each other and so that
the parallel streaming of
different transponders be-
comes possible. But even
here there’s a little calcu-
lation that shows that this
10-12. VLC Installation
might not always be prac-
tical. A single HD channel
typically needs a bandwidth
of around 12MBPS. If you
want to stream four of these
channels to four different
TVs, then it quickly adds up
to 48MBPS and this would
be too much for older WLAN
routers or Access Points
that can only handle up to
56MBPS.
You also have to take into
account that a transport
stream with a single HD
channel and an audio track
needs about 12MBPS, but
when it’s converted into an
IPTV packet, this rate actu-
ally bloats somewhat and
then there’s all the entire
headers that are required
for all the data packets that
need to be considered as
well. Another alternative is
available if you can deal with
reduced picture and audio
quality. Instead of insert-
ing the original transponder
stream into the network,
the received channels can
be recompressed whereby
a stronger compression is
used.
In this way the bandwidth
of a channel can be reduced
to a more reasonable 1MBPS
but unfortunately, you’ll see
this in the picture: all of a
sudden the resolution will
be greatly reduced and be-
cause of this compression
typical artifacts will become
visible such as blocks in the
video and sloppy colors. A
newly compressed stream
like this though can be
streamed in Unicast via the
Internet. The advantage of
IPTV is its incredible flex-
ibility: a large assortment of
devices can be used for re-
ception such as computers,
laptops, game consoles,
tablets, Smartphones and,
of course, IPTV compatibles
TVs. And let’s not forget
how WLAN solves the prob-
lem regarding the otherwise
needed cabling.