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in a specific way to a hit and to the position information stream of one or more axes of control. Pads
ran be grouped into Scenes and the screen of the computer displays the virtual surface and gives visual
feedback to the performer. Performance Pads can control MIDI =.equences. playback of soundhles.
algorithms and real time DSP synthesis. The velocity' of the hits and the position information can be
mapped to different parameters through transfer functions. Control Pads are used to trigger actions
that globally affect the performance.
The architecture of the system has been opened and it is now possible to create interfaces to other MIDI
controllers such as keyboards, pedals, percussion controllers, the Lightning controller and so on. More
than one interface controller can be active at the same time listening to one or more MIDI streams
and each one can map gestures to the triggering and control of virtual pads. The problem of how to
map different simultaneous controllers to the same visible surface has no' been completely resolved at
the time of this writing (having just one controller makes it easy to get simple visual feedback of the
result of the gestures, something that is essential in controlling an improvisation environment). Another
interface that is being currently developed does not depend on MIDI and controls the system through a
standard computer graphics tablet. The surface of the tablet behaves in virtually the same way as the
surface of the Radio Drum, and tablets that have pressure sensitivity open the way to three dimensional
continuous control similar to that of the Radio Drum (but of course not as flexible). The advantage of
this interface is the fact that it does not use MIDI bandwidth and it relies on hardware that is standard
and easy to get.
Performance Pads will have a new category: Algorithmic Pads. These pads can store algorithms that
can be triggered and controlled by gestures of the performer. While a graphical programming interface
has not yet been developed at the time of this writing, the composer can create algorithms easily by
piogramming them in Objective C within the constraints of a built in set of classes and objects that
should be enough for most musical purposes. Any parameter of an algorithm can be linked through
a transfer function to the movement of one of the axes of control. Multiple algorithms can be active
at the same time and can respond in different ways to the same control information making it easy to
transform simple gestures into complicated musical responses. An algorithm can also be the source of
control information that can be used by other algorithms to affect their behavior.
6.1.6 A Dynamic Spatial Sound Movement Toolkit
Fernando Lopez Lezcano
This brief overview describes a dynamic sound movement toolkit implemented within the context of the
CLM software synthesis and signal processing package. Complete details can be found at http://w*wccrma.stanford.edu/
nando/clm/dlocsig/.
diocsig.lisp is a unit generator that dynamically moves a sound source in 2d or 3d space and can be
used as a replacement for the standard locsig in new or existing CLM instruments (this is a completely
rewritten and much improved version of the old dlocsig that I started writing in 1992 while I was working
at Keio University in Japan).
The new dlocsig can generate spatial positioning cues for any number of speakers which can be arbitrarily
arranged in 2d or 3d space. The number of output channels of the current output stream (usually defined
by the xhannels keyword in the enclosing with-sound) will determine which speaker arrangement is used.
In pieces which can be recompiled from scratch this feature allows the composer to easily create several
renditions of the same piece, each one optimized for a particular number, spatial configuration of speakers
and rendering technique.
dlocsig can render the output soundfile with different techniques. The default is to use amplitude
panning between adyacent speakers (between two speakers in 2d space or three speaker groups in 3d
space), dlocsig can also create an Ambisonics encoded four channel output soundfile suitable for feeding
into an appropriate decoder for multiple speaker reproduction. Or it can decode the Ambisonics encoded
information to an arbitrary number of output channels if the speaker configuration is known in advance.
In the near future dlocsig will also be able to render to stereo soundfiles with hrtf generated cues for
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