This paper presents an overview of the sound processing applications of the Sound Object (SndObj) Library version 2.0. The SndObj library is an object-oriented sound synthesis and processing programming library. It is designed for the development of music applications, as well as research and implementation of DSP algorithms. The paper includes a brief but comprehensive description of the library class trees. It also presents the new features and changes introduced in the latest version of the library. A discussion of sound processing and synthesis programs, including some code examples, completes this article.

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Object-oriented programming (OOP) has been for many years now one of the most important programming paradigms used in a variety of applications. Digital audio signal processing can benefit largely from this approach for systems development. In this paper a number of approaches to using object-orientation in audio processing systems are reviewed. Existing systems of audio processing are introduced and discussed in detail. The paper also draws attention to the different OOP techniques enabled and supported by these systems. Comparative code and tutorial examples are included, providing an insight into the development of signal processing applications using objects.

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We present an object-oriented implementation for sinusoidal modelling based on the C++ Sound Object Library (SndObj). We outline the background to this analysis/synthesis technique and its inclusion in many well known methods of speech and music signal processing. Incorporation of such a well known technique into the SndObj library will enable the development of further audio processing techniques such as vocoding, time and pitch scaling and cross-synthesis on an object-oriented development platform.

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This paper describes a new rapid development environment for digital audio applications and computer instruments, AIDE (Audio Instrument Development Environment). The system is designed to help users build signal processing applications for use in music, multimedia and sound design. Based on a graphical patching principle, this system generates software using the V and Sound Object libraries. These provide the graphical interface/application framework and sound processing elements, respectively, for standalone programmes generated by AIDE. It is envisaged that the system will also generate application components in addition to stand-alone programs. The paper outlines in some detail the elements involved in the software. It discusses how the system is aimed at different types of users with different levels of interaction. The paper concludes with an overview of the typical application development cycle using the system.

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This text looks at the computer instrument development work and its influence on the composition process. As a preamble to the main discussion, the different types of software for sound generation and transformation are reviewed. The concept of meta-themes is introduced and explored in the context of contemporary music. Two examples of the author’s computer music work are used to discuss the complex relationship between software development and composition. The first piece provides an example of such relationships in the context of ‘tape’ music. The second explores the use of computer instruments in live electroacoustic music. The activities of composition and instrument creation will be shown to be at times indistinguishable and mutually dependent.

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This article presents new spectral analysis-synthesis approaches to musical signal transformation. The analysis methods presented here involve the use of a superior quality technique of frequency estimation, the Instantaneous Frequency Distribution (IFD), and partial tracking. We discuss the theory behind the IFD, comparing it to other existing methods. The partial tracking analysis employed in this process is explained fully. This is followed by a look into the three resynthesis methods proposed by this work, based on different approaches to additive synthesis. A number of transformations of musical signals are proposed to take advantage of the analysis-synthesis techniques. Performance details and specific aspects of this implementation are discussed. This is complemented by a look at some of the results of these methods in the time-stretching of audio signals, where they will be shown to perform better than many of the currently available techniques.

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In this paper we compare the performance of a number of different templates for the purposes of split point identification of various clarinet envelopes. These templates were generated with AttackDecay-Sustain-Release (ADSR) descriptions commonly used in musical synthesis, along with a set of real templates obtained using k-means clustering of manually prepared test data. The goodness of fit of the templates to the data was evaluated using the Dynamic Time Warping (DTW) cost function, and by evaluating the square of the distance of the identified split points to the manually identified split points in the test data. It was found that the best templates for split point identification were the synthetic templates followed by the real templates having a sharp attack and release characteristic, as is characteristic of the clarinet envelope.

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This article discusses the implementation of frequency domain digital audio effects using the Csound 5 music programming language, with its streaming frequency-domain signal (fsig) framework. Introduced to Csound 4.13, by Richard Dobson, it was further extended by Victor Lazzarini in version 5. The latest release of Csound incorporates a variety of new opcodes for different types of spectral manipulations. This article introduces the fsig framework and the analysis and resynthesis unit generators. It describes in detail the different types of spectral DAFx made possible by these new opcodes.

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This article discusses some developments relating to environments for Csound programming, composition and performance. It introduces the Csound 5 API and discusses its use in the development of a TclTk scripting interface, TclCsound. The three components of TclCsound are presented and discussed. A number of applications, from simple transport control of Csound to client-server networking are explained in some detail. The new multi-platform version of CECILIA is presented. Cecilia is the first Csound frontend to use the functionalities of TclCsound.

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This article describes an adaptive synthesis technique based on frequency (phase) modulation of arbitrary input signals. The background and motivation for the development of the technique, as well as related work, are discussed. A detailed description of delay line-based phase modulation of sinusoidal and complex signals is provided. The basic design of an implementation of the technique is presented and commented. A series of examples using four different instrumental sources are discussed. The results show a wide range of possible effects through the use of the technique, from addition of higher components, to changes in the odd-even harmonic balance and the introduction of controlled inharmonicity.

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