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124 TELE-audiovision International — The World‘s Largest Digital TV Trade Magazine — 05-06/2013 — TELE-audiovision.com
involved and which means
they can be used in the net-
work with full bandwidth.
But Unicast has one prob-
lem: what happens when
two, thee or even more us-
ers request the same TV
channel? The server has
to then route the channel
individually to the various
TVs which will in turn put a
load on the network’s band-
width. It could happen that
the network connection be-
tween the server and the
switch could easily be over-
loaded by the vast amount
of data such that the video
output at the TV might be-
come intermittent or stop
altogether.
In cases like this Multi-
cast would be much more
elegant. With Multicast the
data packets are sent in
parallel to all of the con-
nected TVs and if you want
to, you can receive the data
stream, and if you don’t
want to, you simply don’t
access the data stream. The
server only needs to send
the data packet through the
switch one time. The switch
in turn routes the data pack-
et to not just one TV, but all
of the connected network
adapters.
But even this technique
has its drawbacks; just like
that all of the network con-
nections have to deal with
a heavy amount of data
traffic. When two non-par-
ticipating computers want
to exchange data between
themselves, a portion of
the network bandwidth is
no longer available. Even
though these two comput-
ers are not being used to
watch TV, the line will still
be occupied with IPTV data.
Additionally, with Multi-
cast it’s typical for rout-
ers that are not specifically
configured to not pass on
these data packets. If you
allow the router to config-
ure itself at home, Multicast
streaming over the pub-
lic Internet usually doesn’t
work because the routers
from nearly every Internet
provider can’t pass on these
packets. That’s why stream-
ing via the Internet for pri-
vate users only works with
Unicast. But wait! That fact
that it does work is proven
by all of the IPTV providers
that can be found in the In-
ternet: they are definitely
using Multicast to route TV
channels to an IPTV receiv-
er; they have special access
to the Internet.
Putting it all together, we
can say this: for private
IPTV applications Unicast
is in most cases the cor-
rect solution; if you want to
serve multiple users with
IPTV, such as in hotels or
apartment blocks, then Mul-
ticast is the way to go.
If you want to take part
in IPTV at home, you really
don’t need all that much: a
Linux receiver or a PC with
an integrated reception card
would be the server and a
normal computer or laptop
would be the TV device. In
most cases, Linux receivers
already have a web front-
end installed in the firm-
ware.
If you call up the IP ad-
dress of the Linux receiver
in the computer’s browser,
you can choose a chan-
nel and watch it on the PC.
To do this you click on the
small TV symbol to load an
m3u stream file. This is then
opened for example with
VLC and just like that you
can watch a live stream on
your PC.
This functions quite well
although with a Linux re-
ceiver it is always one user
that can watch a specific
channel. Through Unicast
streaming, only one user
6-9. VLC Installation