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 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 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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The problem of signal synthesis from bilinear time-frequency representations such as the Wigner distribution has been investigated [1,2,4] using methods which exploit an outer-product interpretation of these distributions. The Modal distribution is a timefrequency distribution specifically designed to model the quasiharmonic, multi-sinusoidal, nature of music signals and belongs to the Cohen general class of time-frequency distributions. Existing methods of synthesis from the Modal distribution [3] are based on a sinusoidal-analysis-synthesis procedure using estimates of instantaneous frequency and amplitude values. In this paper we develop an innovative synthesis procedure for the Modal distribution based on the outer-product interpretation of bilinear timefrequency distributions. We also propose a streaming objectoriented implementation of the resynthesis in the SndObj library [6] based on previous work which implemented a streaming implementation of the Modal distribution [7]. The theoretical background to the Modal distribution and to signal synthesis of Wigner distributions is first outlined followed by an explanation of the design and implementation of the Modal distribution synthesis. Suggestions for future extensions to the synthesis procedure are given.

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Techniques for the generation of bandlimited signals for application to digital implementations of subtractive synthesis have been researched by a number of authors. This paper hopes to contribute to the variety of approaches by proposing a technique based on Frequency Modulation (FM) synthesis. This paper presents and explains the equations required for bandlimited pulse generation using modified FM synthesis. It then investigates the relationships between the modulation index and the quality of the reproduction in terms of authenticity and aliasing for a sawtooth wave. To determine the performance of this technique in comparison to others two sets of simulation results are offered: the first computes the relative power of the non-harmonic components, and the second uses the Perceptual Evaluation of Audio Quality (PEAQ) algorithm. It is shown that this technique compares well with the alternatives. The paper concludes with suggestions for the direction of future improvements to the method.

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This article provides an overview of further methods for producing hybrid natural-synthetic spectra with adaptive frequency modulation (AdFM). It focuses on three different techniques for the generation of asymmetric spectra based on single-sideband FM, asymmetric FM and Split-sideband synthesis. The first two techniques are applied to the variable delay line implementation of AdFM, whereas the third is based on an extension of the heterodyne method. The article discusses the principles involved in each synthesis technique in good detail, providing one reference implementation for each. A number of examples are discussed, demonstrating the possibilities for a variety of digital audio effects applications.

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This article discusses Phase Distortion synthesis and its application to arbitrary input signals. The main elements that compose the technique are presented. Its similarities to Phase Modulation are discussed and the equivalence between the two techniques is explored. Two alternative methods of distorting the phase of an arbitrary signal are presented. The first is based on the audio-rate modulation of a first-order allpass filter coefficient. The other method relies on a re-casting of the Phase Modulation equation, which leads to a heterodyned form of waveshaping. The relationship of these implementations to the original technique is explored in detail. Complementing the article, a number of examples are discussed, demonstrating the application of the technique as an interesting digital audio effect.

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This is a study on a set of feedback amplitude modulation oscillator equations. It is based on a very simple and inexpensive algorithm which is capable of generating a complex spectrum from a sinusoidal input. We examine the original and five variations on it, discussing the details of each synthesis method. These include the addition of extra delay terms, waveshaping of the feedback signal, further heterodyning and increasing the loop delay. In complement, we provide a software implementation of these algorithms as a practical example of their application and as demonstration of their potential for synthesis instrument design.

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