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Equipe Analyse/Synthèse
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The Diphone Program:
New Features, New Synthesis Engines and Experience of Musical Use
Xavier Rodet & Adrien Lefevre
to appear in
Proc. ICMC97, Thessaloniki, Grece, September 1997
Abstract
Generalized Diphone Control is a powerful means of building
a musical phrase from dictionnaries of analysed sound units
by building sequences of units and concatenating and
articulating them. The Diphone program is now a mature
software composed of two parts. On the one hand, a sequence
concatenation and parameter computation engine running on
Macintosh or Unix platforms, and, on the other hand, a
graphic user interface running on Macintosh.
This interface is, as much as possible, compliant with the
Macintosh Human Interface Guidelines (Wysiwyg, copy/paste,
drag&drop, etc.). We present new developments and
features of this program as well as the experience
that has been obtained, concerning its musical usage,
after a year of work with musicians and composers.
Even though Generalized Diphone Control is aimed at providing
control parameters for any synthesis method, the first version
controlled only an additive synthesis engine. Implementing other
engines without care could have lead to a large piece of software
resulting in many difficulties well known in software development
and maintenance. Therefore, the program has been cut into
separate modules using shared libraries and plugins.The core does
sequence concatenation, independantly of
the synthesis model under use. Peripheral plugins are
in charge of the computation of parameter streams for
specific synthesis methods and of the synthesis engines
themselves. Furthermore, computations accomplished by
plugins are done in the background, leaving the interface
free for the user. The aim is also that plugins could be
written by users according to their specific needs.
Several new features have been added to the Diphone program.
The first one is a break point function editor allowing
for editing not only scalar functions but also vector functions
such as sinusoidal partial frequencies or formant data.
Editing of diphone sequences has been much improved:
segments can now be time warped and truncated,
sequences can be given in a script file which allows for
their definition in different musical representation
programs such as Patchwork. Rythmic grids can also be
entered from files. Vertical (pitch) and horizontal
scales (time, beats, ticks) have been improved.
A fast sonic "preview" has been added: by clicking on
the icon of a diphone, one can now hear its sound
synthesised without any delay. The additive analysis has been
ported and is implemented as another plugin.
It is also set up and launched from a graphic user interface.
Diphone segmentation of recorded sounds is available from
the Audiosculpt program. This renders the building of
diphone dictionnaries very fast and easy.
Finally Diphone has been completed with the control
of the Chant synthesis model and with a Chant synthesis
engine allowing for the description of different
patches, polyphony and fast synthesis.
Since its release, Diphone has been used by various
composers in different applications. For instance,
an unforseen application has appeared to be in the
preparation of (additive) data for use in real-time
synthesis. The novel characteristics of the Diphone
program have opened new perspectives in vocal and
instrumental sound processing. In particular, musical
materials which were difficult to conciliate (e.g.
discrete structures versus continuous ones),
can now be exploited in a very flexible way.
Moreover, the possibility of controlling different synthesis
methods from the same program allows a more global
control of musical aspects of sound synthesis.