Networking Reference
In-Depth Information
line speeds into a single data stream. This standard has been
officially adopted by ISO [ISO 13818-1].
MPEG-4, in its MPEG4-AVC-Part 10-High Profile version,
which is also called H264 or simply MPEG4, is in the process of
replacing MPEG2. It nevertheless incorporates the MPEG2
transport stream in order to allow its transmission by systems
currently in place.
MPEG4 significantly improves the processes which compress
moving images and sound tracks. For video, the result is that the
necessary bit rate for the transmission of a TV program is roughly
half of that necessary to carry the same TV program when
compressed in MPEG2, with the same level of quality. In addition,
MPEG4 can operate at low speeds, from 64 kbps, which allows low
definition television transmission, whereas MPEG2 becomes
unusable below 1 Mbps.
2.2.2. DVB
DVB (Digital Video Broadcast) is a set of standards set out by
the DVB consortium, and adopted by the ETSI.
DVB defines:
- how to transmit MPEG-2 signals (or MPEG-4, which use the
same transport stream) by satellite, cable or by terrestrial radio
broadcasting. Broadband (IP) transmission takes part of the
specifications initially made for “broadcast” transmission of DVB-
T;
- how to transmit system information and program guides by
using coding systems used to protect the signal.
Apart from the United States, Mexico, Canada and South
Korea, DVB has been adopted by all the countries in the world for
digital radio and television.
Today, DVB comprises:
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