📄 （2）mpeg-4 systems overview.htm
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<P align=center>M<A name=_Ref443155765></A>PEG-4 Systems:
Overview</P></B></FONT>
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<P align=justify>Olivier Avaro<BR>Deutsche Telekom - Berkom GmbH<BR>Abt.
T.22<BR>D-64307 Darmstadt<BR>Deutschland<BR>Mail: <A
href="mailto:o.avaro@berkom.de">o.avaro@berkom.de</A></P></TD>
<TD vAlign=top width="33%">
<P align=justify>Alexandros Eleftheriadis<BR>Columbia University, Dept. of
Electrical Engineering<BR>500 West 120th Street, Mail Code 4712<BR>New
York, NY 10027<BR>USA<BR>Mail: <A
href="mailto:eleft@ee.columbia.edu">eleft@ee.columbia.edu</A></P></TD>
<TD vAlign=top width="33%">
<P align=justify>Carsten Herpel<BR>Deutsche Thomson-Brandt
GmbH<BR>Karl-Wichert-Allee 74<BR>30625 Hannover<BR>Deutschland<BR>Mail: <A
href="mailto:herpelc@thmulti.com">herpelc@thmulti.com</A></P></TD></TR>
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<TD vAlign=top width="33%">
<P align=justify>Ganesh Rajan<BR>General Instrument<BR>6450 Sequence
Dr.<BR>San Diego 92121 CA<BR>USA<BR>Mail: <A
href="mailto:grajan@procy.gi.com"><U>ganesh_rajan@hotmail.com</U></A></P></TD>
<TD vAlign=top width="33%">
<P align=justify>Liam Ward<BR>Teltec Ireland, DCU<BR>Dublin
9<BR>Ireland<BR>Mail: <A
href="mailto:liam.ward@teltec.dcu.ie">liam.ward@teltec.dcu.ie</A></P></TD>
<TD vAlign=top width="33%"></TD></TR></TBODY></TABLE></CENTER></DIV>
<P align=justify>Abstract</P>
<P align=justify>This paper gives an overview of Part 1 of ISO/IEC 14496 (MPEG-4
Systems). It first presents the objectives of the MPEG-4 activity. In the MPEG-1
and MPEG-2 standards, "Systems" referred only to overall architecture,
multiplexing, and synchronization. In MPEG-4, in addition to these issues, the
Systems part encompasses scene description, interactivity, content description,
and programmability. The description of the MPEG-4 specification follows,
starting from the general architecture up to the description of the individual
MPEG-4 Systems tools. Finally, a conclusion describes the future extensions of
the specification, as well as a comparison between the solutions provided by
MPEG-4 Systems and some alternative technologies.</P>
<P align=justify>Keywords</P>
<P align=justify>APIs, Architecture, Audio-visual, Buffer Management,
Composition, Content Description, Interactivity, MPEG-4 Systems, Multiplex,
Programmability, Scene Description, Specification, Synchronization, Tools.</P>
<P align=justify> </P><B><FONT size=4>
<P align=center>Table of contents</P></FONT></B>
<P align=justify><B><I>1. Introduction </I></B><A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054793">*</A>
</P>
<P><I><B>2. Objectives </B></I><A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054794">*</A></P>
<P><B>2.1 Requirements </B><A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054795">*</A></P>
<P><B>2.2 Traditional MPEG Systems Requirements </B><A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054796">*</A></P>
<P><B>2.3 MPEG-4 Specific Systems Requirements </B><A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054797">*</A></P>
<P><B>2.4 What is MPEG-4 Systems? </B><A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054798">*</A></P>
<P><I><B>3. Architecture </B></I><A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054799">*</A></P>
<P><I><B>4. Tools </B></I><A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054800">*</A></P>
<P><B>4.1 Stream Management: The Object Description Framework </B><A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054801">*</A></P>
<P><B>4.2 Presentation Engine: BIFS </B><A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054802">*</A></P>
<P><B>4.3 Timing and Synchronization: The Systems Decoder Model (SDM) and the
Sync Layer </B><A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054803">*</A></P>
<P><B>4.4 The Transport of MPEG-4 Content </B><A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054804">*</A></P>
<P><I><B>5. Conclusion </B></I><A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054805">*</A></P>
<P><B>5.1 Extensions of the Specification </B><A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054806">*</A></P>
<P><B>5.2 MPEG-4 Systems and Competing Technologies </B><A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054807">*</A>
<DIR>
<P>5.2.1 Transport <A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054808">*</A></P>
<P>5.2.2 Streaming Framework <A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054809">*</A></P>
<P>5.2.3 Scene Description Representation <A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054810">*</A></P></DIR>
<P><B>5.3 The key features of MPEG-4 Systems </B><A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054811">*</A></P>
<P><I><B>6. Acknowledgments </B></I><A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054812">*</A></P>
<P><I><B>7. References </B></I><A
href="http://leonardo.telecomitalialab.com/icjfiles/mpeg-4_si/3-systems_overview_paper/3-systems_overview_paper.htm#_Toc458054813">*</A></P>
<P align=justify> </P>
<OL>
<LI><FONT size=4><B><A name=_Toc458054793>Introduction</A></B></FONT> </LI></OL>
<P align=justify>The concept of "Systems" in MPEG has evolved dramatically since
the development of the MPEG-1 and MPEG-2 standards. In the past, "Systems"
referred only to overall architecture, multiplexing, and synchronization. In
MPEG-4, in addition to these issues, the Systems part encompasses scene
description, interactivity, content description, and programmability. The
combination of the exciting new ways of creating compelling interactive
audio-visual content offered by MPEG-4 Systems, and the efficient representation
tools provided by the Visual and Audio parts, promise to be the foundation of a
new way of thinking about audio-visual information.</P>
<P align=justify>This paper gives an overview of MPEG-4 Systems. It is
structured around the objectives, architecture, and the tools of MPEG-4 Systems
as follows:</P>
<UL>
<LI><B>Objectives</B>: This section describes the motivations and the
rationale behind the development of the MPEG-4 Systems specifications. As with
all MPEG activities, MPEG-4 Systems is guided by a set of requirements [1],
i.e., the set of objectives that must be satisfied by the specifications
resulting from the work or activities of the sub-group. This paper give a
particular attention to the way the requirements of MPEG-4 Systems are derived
from the principal concept behind MPEG-4, viz., the coding of audio-visual
objects.
<LI><B>Architecture</B>: This section describes the overall structure of
MPEG-4, known as the "MPEG-4 Systems Architecture". A complete walkthrough of
an MPEG-4 session highlights the different phases that a user will, in
general, follow in consuming MPEG-4 content.
<LI><B>Tools</B>: MPEG-4 is a "toolbox" standard, providing a number of tools,
sets of which are particularly suited to certain applications. This section
provides a functional description of the MPEG-4 Systems tools. These tools are
further described in the sections that follow, and are fully specified in [2]
and [3]. </LI></UL>
<P align=justify>Of course, MPEG-4 is not the only initiative that attempts to
provide solutions in the area described above. Several companies, industry
consortia, and even other standardization bodies have developed technologies
that, to some extent, also aim to address objectives similar to those of MPEG-4
Systems. In concluding this look at MPEG-4 Systems, this paper provides an
overview of some of these alternative technologies and makes a comparison with
the solutions provided by MPEG-4 Systems.</P>
<OL>
<LI><A name=_Ref441461909></A><FONT size=4><B><A
name=_Toc458054794>Objectives</A></B></FONT>
<OL>
<LI><B><A name=_Toc458054795>Requirements</A></B> </LI></OL></LI></OL>
<P align=justify>To understand the rationale behind the activity, a good
starting point is one of the most fundamental MPEG-4 documents, viz., the MPEG-4
Requirements [1]. This document gives an extensive list of the objectives that
needed to be satisfied by the MPEG-4 specifications. The goal of specifying a
standard way for the description and coding of audio-visual objects was the
primary motivation behind the development of the tools in the MPEG-4
Systems.</P>
<P align=justify>MPEG-4 Systems requirements may be categorized into two
groups:</P>
<UL>
<LI><B>Traditional MPEG Systems Requirements</B>: The core requirements for
the development of the systems specifications in MPEG-1 and MPEG-2 were to
enable the transport of coded audio, video and user-defined private data, and
to incorporate timing mechanisms to facilitate synchronous decoding and
presentation of these data at the client side. These requirements also
constitute a part of the fundamental requirements set for MPEG-4 Systems. The
evolution of the traditional MPEG Systems activities to match the objectives
for MPEG-4 Systems is detailed in Section 2.2.
<LI><B>Specific MPEG-4 Systems Requirements</B>: The requirements in this set,
most notably, the notions of <I>audio-visual objects</I> and <I>scene
description</I>, represent the ideas central to MPEG-4 and are completely new
in MPEG Systems. The core competencies needed to fulfil these requirements
were not present at the beginning of the activity but were acquired during the
standards development process. Section 2.3 describes these specific MPEG-4
Systems requirements. </LI></UL>
<P align=justify>To round out this discussion on the MPEG-4 objectives, section
2.4 finally provides an answer to the question "What is MPEG-4 Systems?" by
summarizing the objectives of the MPEG-4 Systems activity and describing the
charter of the MPEG-4 Systems sub-group during its four years of existence.</P>
<OL>
<OL>
<LI><A name=_Ref441289990></A><B><A name=_Toc458054796>Traditional MPEG
Systems Requirements</A></B> </LI></OL></OL>
<P align=justify>The work of MPEG traditionally addressed the representation of
audio-visual information. In the past, this included only natural audio and
video material. As we will indicate in subsequent sections, the types of media
included within the scope of the MPEG-4 standards have been significantly
extended. Regardless of the type of the media, each one has spatial and/or
temporal attributes and needs to be identified and accessed by the application
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