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Legacy Projects

DIGITAL INSTRUMENT for ADDITIVE SOUND SYNTHESIS (DIASS).

DIASS is a M4C instrument for additive synthesis. It was conceived with composers in mind and allows a very large number of partials for each sound as well as minute control over their behaviour. Partials can be exactly tuned or may form an inharmonic spectrum; during the duration of the sound a movement between these two alternatives may occur: out of tune overtones focusing and forming a timbre or a well defined timbre being decomposed into individual sine waves. Due to the very large number of controls and inputs, diassin, a score writer is necessary to facilitate the handling of the instrument. DIASS runs both on the IBM RS-6000 and NeXT computers in CMP and on the IBM SP at Argonne National Laboratory.

MATCHING SYNTHESIS OF MUSICAL INSTRUMENT SOUNDS.

Andrew Horner (Hong Kong University of Science and Technology) and James Beauchamp have collaborated on a project to find efficient models for synthesis of musical instrument tones using techniques for matching synthesized results with the signals produced by original instruments. Models which have been used successfully are multiple-carrier FM, multiple-wavetable, extended nonlinear/filter, and spectral envelope synthesis. An important goal is to identify spectrally-related parameters which have a strong correlation to timbral perception and which operate appropriately over wide ranges of pitch and amplitude. Horner and Beauchamp's most recent effort has been to synthesize trumpet tones using time-variant/pitch-variant spectral envelope synthesis. A model has been designed which runs under Music 4C, making it convenient for composers to experiment with.

COMPUTER-ASSISTED COMPOSITION

Between 1973 and 1991 most of Sever Tipei's music was produced with MP1, a FORTRAN program. Over the years, MP1 has preserved its conceptual framework (sounds as events in a vector space) while new features were continuously added and old ones re-written. MP1 has a stochastic layer whose output could be further structured through logical filters (sieves) and patterns (Markov chains). Since all decisions ultimately depend on a set of random numbers, multiple variants of the same piece can be produced by changing the seed for the random number generator. A collection of such multiple realizations of the same data and using the same program forms a composition class or a Manifold Composition. In 1986 MP1 became the first Computer-assisted Composition to be implemented on a supercomputer (NCSA's CRAY X-MP)

AUTOMATIC MUSIC PRINTING:

GrafChord is an interface between MP1 and SCORE. GrafChord reads in an ASCII file containing the description of sounds in a composition produced with MP1 or other composition programs. The input file includes start time, duration, pitch, plus an arbitrary number of other parameters. Its output is also an ASCII file containing instructions for the music printing/editing program SCORE which is commercially available. The information is translated automatically and appears on the printed page of music. At the present time, parametric values other than durations, pitch (including chords) and dynamics still require some editing by hand.

More recently, DISSCO, has acquired the capability of automatic music printing in connection with FOMUS and LilyPond.

SOUND ANALYSIS.

ARMADILLO

The primary objective of Armadillo is to provide a convenient way to quickly analyze musical sounds on an inexpensive computer without the need for specialized hardware. The development of high speed computers with excellent graphics and high quality audio I/O for the general consumer in the last few years has made this possible. While a number of analysis programs are available on the Intel or Macintosh platforms, there are few that are dedicated to the analysis of musical sounds as Armadillo is.

MUSIC VISUALIZATION AND SCIENTIFIC SONIFICATION: M4CAVE

Visual and aural images can be produced from exactly the same data with the help of M4cave and DIASS. A C++ program using the OpenGL garphic libraries, M4cave runs in the CAVE, an immersive, room-size, 3-d environment and on the Immersadesk (a scaled down, 2-D version of the CAVE). A simulator version of it runs on the CMP SGI O2. M4cave has been used to "visualize" musical compositions and, together with DIASS, it is a promissing tool for the analysis of scientific data representing the output of computational experiments.

 

HARDWARE PLATFORMS FOR CMP SOFTWARE

Music 4C will run with minor modifications on any Unix computer. Most SNDAN programs will run on any Unix computer, but a PostScript viewer is needed for screen graphics, unless Tektronix emulation is used. DISSCO runs on UNIX/Linux (Ubuntu) computers; MP1, GrafChord, DIASS can be implemented on any Unix computer. M4cave runs on SGI machines (IRIX 6.0 or higher) on which OpenGL reside.