TC Electronic Broadcast 6000 - Manual (Page 50)

50
paGe Head rOOm sImulaTIOn fOr mulTICHannel musIC and fIlm
Room Simulation
for Multichannel Film and Music
Presented at the AES 107th Convention, New York, NY,
1999 September 24-27. Republished with permission
from the AES, www.aes.org
KNUD BANK CHRISTENSEN AND THOMAS LUND
TC Electronic A/S
Sindalsvej 34,
DK-8240 Risskov,
DENMARK
To fully exploit new Reverb and Spatial algorithms for
5.1 and 7.1 environments in music and film, effect mixing
procedures may have to be changed slightly.
The paper will describe production techniques for
positioning of sources and listener in virtual rooms, and an
algorithm structure to achieve this.
0. INTRODUCTION
Typical production techniques involve only one or two
inputs to the room simulation system, thereby limiting the
precision of source positioning to be only a matter of send
level differences and power panning. This “one source -
one listener” model is not very satisfying when producing
for mono or stereo, but even worse when the reproduction
system is multichannel.
Multichannel recording and reproduction is an opportunity
for the production engineer to discriminate deliberately
between scenes or instruments heard from a distance, and
sources directly engaging the listener.
For film work, engaging audio has a very pronounced effect
for stimulating the viewer emotionally, and may therefore
significantly add to the illusion presented by the picture.
In the search of more authenticity in artificial room
generation, long term studies of natural early reflection
patterns have led us to propose new production and
algorithm techniques. Using ray tracing in conjunction with
careful adjustments by ear, we have achieved simulation
models with higher naturalness and flexibility, which is the
basis of true source positioning.
The paper will discuss two aspects of precise room
simulation for multi source, multichannel environments to
cover distant and engaged listening:
• Present different production techniques
• Describe an algorithm structure to achieve the objectives
1. SINGLE SOURCE REVERB
By having only one or two inputs in a room simulator,
the rendering is based upon multiple sources sharing the
same early reflection pattern, and therefore it is not really
convincing.
In the real world, all actors or instruments are not piled up
on top of each other.
Introduction
For more than 10 years TC Electronic has put considerable
research resources into perfecting digital room simulation.
Our achievements have been made possible by combining
scientific room models with intensive listening tests and
perceptual adjustments.
This is also the case with the VSS5.1 room simulator
which is the crown jewel of the algorithms included with
System 6000.
For this specific research project, the work started in 1995
on powerful Silicon Graphics computers, so we could ready
ourselves for today with plenty of real-time DSP power
available. Some of our work was made public in an AES
paper written in April 1999 and published September at
AES in New York City.
The unique combination of objective tests and scientific
modeling described has won acceptance in our industry
and is now the angle generally used for finding the right
balance between emotional impact, controllability and
range of credible results.
VSS5.1 covers from natural over super-natural to wild, wild
spaces.