TCP/IP Tutorial and Technical Overview - IBM Redbooks

21.2 Functional components
Figure 21-2 illustrates the major functional components in IPTV.
Figure 21-2 IPTV functional components
21.2.1 Content acquisition
Acquire Encode Transmit Decode
The first step in IPTV is acquisition of the contents to be broadcast. Here we
focus on the IP networking technical aspects:
► Multiple IP network interconnections are required between the content
service provider infrastructure and that of the IPTV application service
provider.
► IP video differs from a traditional cable or satellite TV architecture in that the
radio frequency or RF signal is sampled, packetized, and encapsulated into
packets for delivery over a IP-based broadband network.
► The acquired contents have to be in one or more video content warehouses,
where the titles have to be searchable. For this purpose, traditional DNS can
be extended to some aspects of the service level.
► Normally, the distribution network is arranged as a hierarchical layout. The
top distribution router has to handle a higher volume of IP traffic, and the
regional hub can store and route to local areas. Transport between the top
level and the regional hubs can be dedicated IP networks, while the lower
hierarchical distribution layer can use a shared IP network infrastructure.
21.2.2 CODEC (encode and decode)
A CODEC is the combination of coder and decoder. The CODEC can also
compress and expand the video signals.
There are several reasons for encoding the signals:
► Compression
The bandwidth required to transmit uncompressed video exceeds the
limitations of most network technologies today.
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