?? （1）mpeg-4 why, what, how and when.htm
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<P><B><FONT size=+3>MPEG-4: Why, What, How and When?</FONT></B>
<P><B><FONT size=+2>Fernando Pereira</FONT></B>
<P><I><FONT size=+1>Instituto Superior T閏nico - Instituto de
Telecomunica琿es</FONT></I> <BR><I><FONT size=+1>Av. Rovisco Pais, 1049-001
Lisboa Codex, Portugal</FONT></I> <BR><I><FONT size=+1>E-mail:
Fernando.Pereira@lx.it.pt</FONT></I></CENTER>
<P><BR><BR><BR>
<P><B><I><FONT size=+1>Abstract</FONT></I></B>
<P><I>The MPEG-4 Version 1 standard has been recently finalized. Since MPEG-4
adopted an object-based audiovisual representation model with hyperlinking and
interaction capabilities and supports both natural and synthetic content, it is
expected that this standard will become the information coding playground for
future multimedia applications.</I> <BR><I>This paper intends to give an
overview on the MPEG-4 motivations, objectives, achievements, process and
workplan, providing a stimulating starting point for more detailed reading.</I>
<BR>
<P><B><FONT size=+1>1. Why: The Context</FONT></B>
<P>"What does it mean, to see? The plain man抯 answer (and Aristotle抯, too)
would be, to know what is where by looking. In other words, vision is the
process of discovering from images what is present in the world, and where it
is." [1]. The image coding standards nowadays available, and the underlying
image data models, mainly address this process by providing an image
representation in the form of a sequence of rectangular 2D frames which give the
users "a window to the real world": <I>the Television paradigm</I>. However, the
process of vision is just a part of the task at hand since typically the human
being needs and wants to see, to take actions after, interacting with the
objects that compose the world being seen. A similar reasoning can be made
regarding the process of hearing and the corresponding audio representation
models.
<P>Although the television paradigm dominated audiovisual communications for
many years, the situation is nowadays evolving very quickly in terms of the ways
audiovisual content is produced, delivered and consumed [2]. Moreover hardware
and software are getting more and more powerful, opening new frontiers to the
technologies used and to the functionalities provided.
<P>Producing content is nowadays easier and easier. Digital still cameras
directly storing in JPEG format have hit the mass market. Together with the
first digital video cameras directly recording in MPEG-1 format, this represents
a major step for the acceptance, in the consumer market, of digital audiovisual
acquisition technology. This step transforms every one of us in a potential
content producer, capable of creating content that can be easily distributed and
published using the Internet. Moreover more content is being synthetically
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