"Perhaps the most immediate need for MPEG-4 is defensive. It supplies tools with which to create uniform (and top-quality) audio and video encoders on the Internet, preempting what may become an unmanageable tangle of proprietary formats."
Indeed, if we are looking for a general characterization it
would be that MPEG-4 is primarily
and, moreover, one that is suitable for a variety of
display devices and networks, including low bitrate
mobile networks.
MPEG-4 supports scalability on a variety of levels:
Imagine, a talking figure standing next to a desk
and a projection screen, explaining the contents of
a video that is being projected
on the screen, pointing at a globe that stands on the desk.
The user that is watching that scene decides to
change from viewpoint to get a better look at the globe ...
How would you describe such a scene?
How would you encode it?
And how would you approach decoding
and user interaction?
The data stream (Elementary Streams)
that result from the coding process can be transmitted
or stored separately and need
to be composed so as to create the actual
multimedia presentation at the receivers side.
At a system level, MPEG-4 offers the following
functionalities to achieve this:
that allows for transparent interaction with resources,
irrespective of whether these are available from local
storage, come from broadcast, or must be obtained from
some remote site.
Also transparency with respect to network type is
supported.
Quality of Service is only supoorted to the
extent that it ispossible to indicate needs for
bandwidth and transmission rate.
It is however the responsability of the network provider to
realize any of this.
benefits
Of media objects.
www.eetimes.com/story/OEG20010220S0065
MPEG-4 is "a big standard," said Tim Schaaff, vice president of engineering for Apple Computer Inc.'s Interactive Media Group. "It's got tons of tools inside." Its success, he said, will depend on the industry's willingness to home in on a small subset, winnowing from a number of profiles and levels designed for streaming a slew of digital multimedia types -- audio, several types of video, still images, and 2-D and 3-D graphics.
Some may find it to ambitious.
But, then again, what it offers is clearly worthwhile.
MPEG-4's chief features include highly efficient compression, error resilience, bandwidth scalability ranging from 5 kbits to 20 Mbits/second, network and transport-protocol independence, content security and object-based interactivity, or the ability to pluck a lone image -- say, the carrot Bugs Bunny is about to chomp -- out of a video scene and move it around independently.
And, not altogether unimportant,
it may offer significant commercial benefits.
Broadband service providers, such as cable and DSL companies, are right behind wireless in sizing up MPEG-4, largely because its low bit rate could help them add channels in their broadband pipes while incorporating interactive features in the content. Possibilities include multiple video streams, clickable video, real-time 3-D animation and interactive advertising.
draft version 1 (16/5/2003)
Dependent on network resources and platform capabilities,
the 'right' level of signal quality can be determined
by selecting the optimal codec, dynamically.
media objects
For 3D-scene description, MPEG-4 builds on concepts
taken from VRML (Virtual Reality Modeling Language,
discussed in chapter 7).
In addition, MPEG-4 defines a set of functionalities
For the delivery of streamed data, DMIF, which stands for
authoring
In effect, although MPEG-4 is primarily concerned
with efficient encoding
and scalable transport and delivery,
the object-based approach has also clear
advantages from an authoring perspective.
syntax
when discussing RM3D, we will further establish
whatthe relations between, respectively MPEG-4,
SMIL and RM3D are,
and in particular where there is disagreement,
for example with respect to the timing model
underlying animations and the temporal control of
media objects.
the press
unfocused ambition
[]
readme
preface
1
2
3
4
5
6
7
appendix
checklist
powerpoint
resources
director
eliens@cs.vu.nl
