139 What happened at the MPEG - NY meeting? MPEG-2 Systems
Description
This article is from the MPEG FAQ, by Frank Gadegast phade@cs.tu-berlin.de with numerous contributions by others.
139 What happened at the MPEG - NY meeting? MPEG-2 Systems
MPEG is developing the MPEG-2 Systems Standard to specify coding
formats for multiplexing audio, video, and other data into a form suitable
for transmission or storage. There are two data stream formats defined:
the Transport Stream, which can carry multiple programs simultaneously,
and which is optimized for use in applications where data loss may be
likely, and the Program stream, which is optimized for multimedia
applications, for performing systems processing in software, and for
MPEG-1 compatibility.
Both streams are designed to support a large number of known and
anticipated applications, and they retain a significant amount of
flexibility such as may be required for such applications, while providing
interoperability between different device implementations. The
Transport Stream is well suited for transmission of digital television and
video telephony over fiber, satellite, cable, ISDN, ATM, and other
networks, and also for storage on digital video tape and other devices. It
is expected to find widespread use for such applications in the very near
future.
The Program Stream is similar to the MPEG-1 Systems standard (ISO/IEC
11172-1). It includes extensions to support new and future applications.
Both the Transport Stream and Program Stream are built on a common
Packetized Elementary Stream packet structure, facilitating common
video and audio decoder implementations and stream type conversions.
This is well-suited for use over a wide variety of networks with
ATM/AAL and alternative transports. This week in New York, MPEG
completed definitions of the features, syntax, and semantics of the
Transport and Program Streams, enabling product designers to proceed.
Among other items, the Transport Stream packet length was fixed at 188
bytes, including the 4-byte header. This length is suited for use with ATM
networks, as well as a wide variety of other transmission and storage
systems.
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