technologies

esearch and development – 2016
SIGNAL MODELS
SDIF FORMAT
Sound Interchange Standard Format
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Teams Involved: Sound Analysis & Synthesis, Sound Music Movement
Interaction, Musical Representations
This file format standard, independent from computer
platforms, extendable and freely accessible, details very
precisely the types of audio signal description data and their
representation.
Once their inputs and outputs conform to the same standard,
it enables different pieces of software to communicate
immediately. It also makes the maintenance of data files
much easier thanks to annexed information carried in the
file and enables pieces of heterogeneous data to co-exist
in one file. A library of reading/writing C functions and
applications have been developed and licensed in open
source (http://sdif.sourceforge.net).
PROCESSING BY PHASE VOCODER
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Team Involved: Sound Analysis & Synthesis
The phase vocoder, one of the most effective techniques
for the analysis and transformation of sounds, represents
the foundation of the SuperVP software program. With
the phase vocoder, it is possible to transpose, stretch, or
shorten sounds; it is possible to apply a practically limitless
number of filters to sounds. By the same token, the level
of sound quality of the transformed signals is extremely
high when applied to speech. Numerous improvements and
extensions have been introduced, for example:
• Reassigned spectrum
• Estimation of the spectral envelope via ‘true envelope’
transposition with the preservation of the spectral
envelope transposition with the ‘shape invariant’ model
• Generalized cross synthesis enabling the synthesis of
hybrid sounds
• Several methods for estimating the fundamental
frequency (pitch) of a signal
• Classification by nature of the spectral, sinusoidal (voiced)
or non-sinusoidal (non-voiced sounds or noises) peaks
segmentation of the time/frequency zones into transitory
and non-transitory regions and the increase or decrease
of transitory sections
• Processing the sinusoidal, non-sinusoidal, and transitory
time/frequency zones
• The LF model of a glottal source, making it possible to
transform a voice, etc.
These different modules of analysis, synthesis, and
processing are used in several software programs on the
market today.
CORPUS-BASED CONCATENATIVE
SYNTHESIS
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Team Involved: Sound Music Movement Interaction
Corpus-based concatenative synthesis uses a database
of recorded sounds and a unit selection algorithm that
chooses the segments from the database that best suit
the musical sequence that we would like to synthesize by
concatenation. The selection is based on the characteristics
of the recording obtained through signal analysis and match,
for example, the pitch, energy, or spectrum. The habitual
methods for musical synthesis are based on a model of a
sound signal, but it is very difficult to establish a model
that conserves the entirety of the details and delicacy of
the sound. However, concatenative synthesis—that uses real
recordings—preserves these details.
Putting the new approach for concatenative synthesis
by corpus in real-time in place enables an interactive
exploration of a sound database and a granular composition
that targets specific sound characteristics. It also makes it
possible for composers and musicians to reach new sounds.
This principle is carried out in the CataRT system. This
system makes it possible to display a 2D projection of
the descriptor space that can be browsed using a mouse
or external controllers. Grains are then selected in the
original recording and performed by geometric proximity,
metronome, in loops, or continuously. It is also possible
to define a perimeter around one’s present position that
selects a sub-group of grains that are then played randomly.
CataRT is used for musical composition, performance, and
in various sound installations.
As this field of research is fairly young, several interesting
research questions have been raised (or will be raised in
the future) concerning the analysis and exploitation of the
information found in the data of a corpus, the visualization,
and real-time interaction.
System of visualization used for sound synthesis by corpus
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