Principles

The Chant synthesiser is initialised by the connexion of several synthesis or processing modules : FOF banks (a set of FOF generators), Filter banks (a set of resonant filters), Noise generator, and sound file player.

In the current implementation, 11 configurations (or "patches") are available.

Chant can therefore perform FOF synthesis, but also, for instance, filter an input sound with a resonant filter, add a controlled noise source and merge different configurations of these options (provided the corresponding patch is available among the 11 options).

Chant is controlled via SDIF files (Sound Description Interchange Format) where the state of the synthesis modules are specified at different times (with a free and non-regular rate). The synthesizer interpolates between these states in order to compute the output sound at the final sample rate.

See the Chant/SDIF specification for more detail about the SDIF specification for the control of Chant : http://recherche.ircam.fr/anasyn/sdif/SdifNormDoc.html

Basically, the different tools in OM-Chant will allow to generate this sequence of control frames formatted as an SDIF file, and use this file in a call to the synthesizer.

Two different control approaches are available with OM-Chant :

• The "low-level" control tools of OM-Chant allow to simply generate this sequence of control parameters.
• The "Chant events" framework abstracts this procedutre and automatize the generation of the sequence from higher-level objects.

The FOF synthesizer in Chant consists in a number of parallel FOF generators, all driven by a common impulse train.

FOFs are small sinusoidal grains modulated by a precisely shaped envelope. A train of such grains contributes to the resulting spectrum with a formant, whose central frequency, amplitude, shape and bandwidth can be precisley controlled.

Typically, 5 FOF generators are used to synthesize voice sounds.

The frequency of the pusle train determines the fundamental frequency (or "f0")of the resulting sound.

All the parameters of the FOFs, as well as the global fundamental frequency, are subject to continuous change during the synthesis process.