104 research outputs found
Real-time sound synthesis on a multi-processor platform
Real-time sound synthesis means that the calculation and output of each sound sample for a channel of audio information must be completed within a sample period. At a broadcasting standard, a sampling rate of 32,000 Hz, the maximum period available is 31.25 μsec. Such requirements demand a large amount of data processing power. An effective solution for this problem is a multi-processor platform; a parallel and distributed processing system. The suitability of the MIDI [Music Instrument Digital Interface] standard, published in 1983, as a controller for real-time applications is examined. Many musicians have expressed doubts on the decade old standard's ability for real-time performance. These have been investigated by measuring timing in various musical gestures, and by comparing these with the subjective characteristics of human perception. An implementation and its optimisation of real-time additive synthesis programs on a multi-transputer network are described. A prototype 81-polyphonic-note- organ configuration was implemented. By devising and deploying monitoring processes, the network's performance was measured and enhanced, leading to an efficient usage; the 88-note configuration. Since 88 simultaneous notes are rarely necessary in most performances, a scheduling program for dynamic note allocation was then introduced to achieve further efficiency gains. Considering calculation redundancies still further, a multi-sampling rate approach was applied as a further step to achieve an optimal performance. The theories underlining sound granulation, as a means of constructing complex sounds from grains, and the real-time implementation of this technique are outlined. The idea of sound granulation is quite similar to the quantum-wave theory, "acoustic quanta". Despite the conceptual simplicity, the signal processing requirements set tough demands, providing a challenge for this audio synthesis engine. Three issues arising from the results of the implementations above are discussed; the efficiency of the applications implemented, provisions for new processors and an optimal network architecture for sound synthesis
On the synthesis and processing of high quality audio signals by parallel computers
This work concerns the application of new computer architectures to the creation and manipulation of high-quality audio bandwidth signals. The configuration of both the hardware and software in such systems falls under consideration in the three major sections which present increasing levels of algorithmic concurrency. In the first section, the programs which are described are distributed in identical copies across an array of processing elements; these programs run autonomously, generating data independently, but with control parameters peculiar to each copy: this type of concurrency is referred to as isonomic}The central section presents a structure which distributes tasks across an arbitrary network of processors; the flow of control in such a program is quasi- indeterminate, and controlled on a demand basis by the rate of completion of the slave tasks and their irregular interaction with the master. Whilst that interaction is, in principle, deterministic, it is also data-dependent; the dynamic nature of task allocation demands that no a priori knowledge of the rate of task completion be required. This type of concurrency is called dianomic? Finally, an architecture is described which will support a very high level of algorithmic concurrency. The programs which make efficient use of such a machine are designed not by considering flow of control, but by considering flow of data. Each atomic algorithmic unit is made as simple as possible, which results in the extensive distribution of a program over very many processing elements. Programs designed by considering only the optimum data exchange routes are said to exhibit systolic^ concurrency. Often neglected in the study of system design are those provisions necessary for practical implementations. It was intended to provide users with useful application programs in fulfilment of this study; the target group is electroacoustic composers, who use digital signal processing techniques in the context of musical composition. Some of the algorithms in use in this field are highly complex, often requiring a quantity of processing for each sample which exceeds that currently available even from very powerful computers. Consequently, applications tend to operate not in 'real-time' (where the output of a system responds to its input apparently instantaneously), but by the manipulation of sounds recorded digitally on a mass storage device. The first two sections adopt existing, public-domain software, and seek to increase its speed of execution significantly by parallel techniques, with the minimum compromise of functionality and ease of use. Those chosen are the general- purpose direct synthesis program CSOUND, from M.I.T., and a stand-alone phase vocoder system from the C.D.P..(^4) In each case, the desired aim is achieved: to increase speed of execution by two orders of magnitude over the systems currently in use by composers. This requires substantial restructuring of the programs, and careful consideration of the best computer architectures on which they are to run concurrently. The third section examines the rationale behind the use of computers in music, and begins with the implementation of a sophisticated electronic musical instrument capable of a degree of expression at least equal to its acoustic counterparts. It seems that the flexible control of such an instrument demands a greater computing resource than the sound synthesis part. A machine has been constructed with the intention of enabling the 'gestural capture' of performance information in real-time; the structure of this computer, which has one hundred and sixty high-performance microprocessors running in parallel, is expounded; and the systolic programming techniques required to take advantage of such an array are illustrated in the Occam programming language
Portfolio of Electroacoustic Compositions with Commentaries
This portfolio consists of electroacoustic compositions which were primarily realised
through the use of corporeally informed compositional practices. The manner in which a
composer interacts with the compositional tools and musical materials at their disposal
is a defining factor in the creation of musical works. Although the use of computers in
the practice of electroacoustic composition has extended the range of sonic possibilities
afforded to composers, it has also had a negative impact on the level of physical interaction
that composers have with these musical materials. This thesis is an investigation
into the use of mediation technologies with the aim of circumventing issues relating to
the physical performance of electroacoustic music.
This line of inquiry has led me to experiment with embedded computers, wearable
technologies, and a range of various sensors. The specific tools that were used in the
creation of the pieces within this portfolio are examined in detail within this thesis. I also
provide commentaries and analysis of the eleven electroacoustic works which comprise
this portfolio, describing the thought processes that led to their inception, the materials
used in their creation, and the tools and techniques that I employed throughout the
compositional process
OMChroma: Compositional Control of Sound Synthesis
International audienc
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The Design and Evaluation of Computer Music Interfaces
The purpose of this research is to examine the methods employed to design a computer music system suitable for music composition purposes. The nature of an interface is introduced and discussed (Chapter 2), with particular reference to interfacing issues for computer music users. The nature of the user and the notion of a task in computer music are discussed and examined (Chapter 3), with outline methods for evaluations of users and tasks being introduced. Current computer systems design and analysis methodologies are introduced (Chapter 4), and subsequently adapted for use in computer music design and analysis applications. A set of guidelines is introduced in Chapter 5, specifically related to the design and analysis of computer music systems. These guidelines are formulated from the discussions regarding the interfacing requirements of a musician user and the nature of the tasks he wishes to accomplish employing computer related technology. An examination of several systems forms a major part of the thesis (Chapters 6 - 10), outlining a variety of available composition tools at the time of writing. Each system introduced and discussed is evaluated in relation to the guidelines introduced for design and analysis of computer music systems. An interface design case study (Chapter 11) employs the design methods introduced during the thesis, and highlights the need for intensive designer - user discourse
LC: A Mostly-strongly-timed Prototype-based Computer Music Programming Language that Integrates Objects and Manipulations for Microsound Synthesis
Ph.DDOCTOR OF PHILOSOPH
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General Process in the Creation of Estruendos and Principal Structural Elements of the Composition
My composition, Estruendos, is a work for large symphonic orchestra, guitar and computer-generated and processed sounds on CD. The work lasts 23 minutes and 45 seconds. My dissertation is composed of two parts: Part One comprises the analysis and Part Two comprises the score. Part One gives a brief background of my compositional dialect and aesthetics. It also includes a discussion of the compositional process and general overview of Estruendos. In addition, it illustrates the primary role the placement of sonic events in time and timbral structure play in the pathos of Estruendos
Developing a flexible and expressive realtime polyphonic wave terrain synthesis instrument based on a visual and multidimensional methodology
The Jitter extended library for Max/MSP is distributed with a gamut of tools for the generation, processing, storage, and visual display of multidimensional data structures. With additional support for a wide range of media types, and the interaction between these mediums, the environment presents a perfect working ground for Wave Terrain Synthesis. This research details the practical development of a realtime Wave Terrain Synthesis instrument within the Max/MSP programming environment utilizing the Jitter extended library. Various graphical processing routines are explored in relation to their potential use for Wave Terrain Synthesis
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