IPTV – Television over the Internet - Digital Video and Audio Broadcasting Technology - page 512

VC-1 (Windows Media 9)) and AAC. Currently, four possibilities exist for
transmitting DTV over IP (Fig. 29.2.). The first possibility is proprietary
where MPEG-4 video or possibly. Windows Media 9 (VC-1) is simply
embedded, together with MPEG-4 Audio (AAC), in UDP-packets (i.e.
without handshake). The UDP packets, in turn, are then placed in IP-
packets and then transmitted via Ethernet, WLAN, WiMAX or xDSL. A
further approach, also not standardized at the moment, is to insert video
and audio streams into an MPEG-2-transport stream as specified in the
MPEG-2 and MPEG-4-standards and then to transport this transport
stream in UDP- and IP-packets, e.g. also via xDSL. In the method speci-
fied as part of DVB-IP in the ETS 102034 standard, the RTP (Real Time
Transport Protocol) is additionally inserted between the transport stream
and the UDP layer. In ISMA (Internet Streaming Media Alliance) stream-
ing the transport stream layer is missing but the RTP is used here, also. All
methods have in common that in each case only one program is transmit-
ted on-demand. In the MPEG-2-transport stream, PAT and PMT tables are
inserted for signalling purposes.

TV services over xDSL based IP networks

DVBIP
ETS102034

ISMA

proprietary proprietary

„Streaming“

Video (MPEG4 AVC, VC1)
Audio (MPEG4 AAC)

MPEG2 TS

RTP
Real Time Transport Protocol
UDP
User Datagram Protocol

IP

Ethernet / xDSL / …

Fig. 29.2. IPTV protocols

It remains to be seen how successful this new offer will be compared
with the other three previous TV-propagation paths.

Bibliography: [ITU-T G.993], [ETS102034]