System
Applicability
The auralization techniques
find vast applications
in the areas of virtual
reality, 3D musical
production, multimedia
telecommunications and
immersive television,
allowing to increase
the degree of realism
of the visual presentation,
and to add context-aware
spatial information.
Consider, as an example,
an application in aeronautical
engineering design,
where designers navigate
around an airplane mockup,
for instance interested
in inspecting the air
flow throughout the
fuselage. The noise
associated with the
air turbulent behavior
and with the different
sound intensities in
the diverse points of
the fuselage could be
added to the visual
navigation, offering
a set of acoustics information
relevant to the design,
bringing the simulated
reality to the reach
of the designer.
In a design for insulation
and treatment of the
internal noise for an
airplane the audiovisual
navigation inside of
the virtual mockup would
allow, for example,
to evaluation of the
sound quality and sound
intensity in distinct
points of the cabin,
assisting in the identification
of isolated problems,
imperfections, and in
one better tunning of
the project. A physically-correct
auralization of the
sound field would be
necessary for such activities
in conception and engineering
projects.
Applications directed
toward improvement or
conception of new multimedia
services each time more
request greater realism
and quality in the presentation
of the visual and sound
material. It has an
enormous appeal in the
musical production and
interactive digital
audio consumption in
personal players. For
some applications, for
example the development
of new generations of
teleconference, videofone
or interactive television,
it has an enormous interest
in three-dimensional
models, that can reconstruct
the remote audiovisual
reality, which is three-dimensional.
Systems oriented to
telepresence or sophisticated
proposals for immersive
teleconference already
consider the use of
holographic or stereo
images, not only to
transmit with realism
the remote space characteristics,
but also aiming at producing
a more fluid visual
interface binding the
remote sites. Stereoscopy
and 3D auralization
would allow together
a fusion of the remote
sites on a gradual uniform
way, or could carry
the users to a new environment,
where the visual properties
and 3D acoustics can
be shared.
New generations of
telepresence systems
where the capture of
multiple projections
is a reality also could
adopt the capture of
3D audio, taking into
account its directional
properties. With the
use of fast networks
(for example, Gigabit
Ethernet) and of adequate
techniques for multichannel
multimedia compression
and multiprojection,
it becomes possible
to investigate the limits
and to exercise the
creative capacity in
the conception of sophisticated
applications of 3D multimedia
transmission and rendering.
A soundfield microphone
coupled to an 3D audio
coding technique, as
for example Ambisonics,
could be used to carry
through the capture
and the transmission
of the 3D sound field
from a place to another.
The sound canals can
adequately be codified
and integrated to video
streams, opening enormous
possibilities of interaction,
conception of new applications
and services, contemplating
the 3D audio and video
fusion.
In the area of digital
television (DTV) new
applications associating
the transmission and
reproduction of 3D acoustic
environments are already
viable with systems
based on 5.1 channels,
and even 7.1. Enhanced
surround systems employing
more channels are now
under tests, for instance
in the Japanese ISDB
system, and are being
considered also in the
newer Brazilian DTV
system. Thanks to state-of-the-art
audio codecs (e.g. MPEG-4
AAC) one can deliver
today even dozens of
audio channels, capable
of conveying complex
spatial audio information.
However they still consist
of higher cost applications
and little explored
in respect of content
production possibilities,
interaction and realism
enhancement.
We consider a future
goal in applications
for the Digital Cave
the conception and the
prototyping of an application
with integrated capture,
transmission and 3D
audio and video rendering,
that can be portable
for complete immersive
virtual reality applications,
as well as advanced
applications for digital
TV.
We identify several
application areas, both
in architecture design
and actual system developments:
- function modularization
or separation within
the audio processing
chain, which can be
implemented in different
devices or software
components
- permit the functional
reconfigurability
or scalability by
adding or excluding
functions (reconfigurable
complexity)
- integrated system
for auralization of
an audiovisual scene
described with X3D,
VRML, MPEG-4 or other
scene description
format
- creation of sound
environments and complex
musical scenes, by
adding sound sources
in the virtual space
(orchestration applications)
- acoustical scene
edition, positioning
objects and sound
sources in space
- surround sound
field projection for
usage in shows, theaters,
auditorium, multimedia
presentation, etc.
- permit the portability
and interoperation
of software and devices,
carrying out audio
functions, by standardizing
the signals of importance
flowing between adjacent
functional layers,
which every component
(software or hardware)
should produce at
the interfaces with
other components.
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