The Modal Distribution (MD) is a time-frequency distribution specifically designed to model the quasi-harmonic, multisinusoidal, nature of music signals and belongs to the Cohen general class of time-frequency distributions. The problem of signal synthesis from bilinear time-frequency representations such as the Wigner distribution has been investigated [1,14] using methods which exploit an outer-product interpretation of these distributions. Methods of synthesis from the MD based on a sinusoidal-analysis-synthesis procedure using estimates of instantaneous frequency and amplitude values have relied on a heuristic search ‘by eye’ for peaks in the time-frequency domain [2,7,8]. An approach to detection of sinusoidal components with the Wigner Distribution has been investigated in [15] based on a comparison of peak magnitudes with the DFT and STFT. In this paper we propose an improved frequency smoothing kernel for use in MD partial tracking and adapt the McCauley-Quatieri sinusoidal analysis procedure to enable a sum of sinusoids synthesis. We demonstrate that the improved kernel enhances automatic partial extraction and that the MD estimates of instantaneous amplitude and frequency are preserved. Suggestions for future extensions to the synthesis procedure are given.

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Spectral models provide ways to manipulate musical audio signals that can be both powerful and intuitive, but high-level control is often required in order to provide flexible real-time control over the potentially large parameter set. This paper introduces Metamorph, a new open source library for high-level sound transformation. We describe the real-time sinusoids plus noise plus transients model that is used by Metamorph and explain the opportunities that it provides for sound manipulation.

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This paper investigates a number of digital methods to produce the Analog subtractive synthesis effect of ‘Hard Synchronisation.’ While the original effect is produced by an explicit waveform phase reset, other approaches are given that produce an equivalent output. In particular, based on measurements taken from a real-analog synthesizer, a comb filtering model is proposed. This description ties in with earlier work but here an explicit structure is provided. This filter-based approach is then shown to be far more computationally efficient than the synchronisation by phase reset. This efficiency is at a minor cost as it is shown that it has a minimal impact on the sonic accuracy.

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This paper considers the generation of resonant waveforms from a number of perspectives. Commencing with the well-known source filter model it introduces a more advantageous heterodyne interpretation. Some variations on the basic design and comparisons with previous methods are then given. An analysis on the use of three different digital music filter structures for resonance synthesis is made, followed by an example showing how timbrally rich Frequency Modulated resonant waveforms can be synthesized.

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This paper discusses the development of digital audio effect applications in mobile platforms. It introduces the Mobile Csound Platform (MCP) as an agile development kit for audio programming in such environments. The paper starts by exploring the basic technology employed: the Csound Application Programming Interface (API), the target systems (iOS and Android) and their support for realtime audio. CsoundObj, the fundamental class in the MCP toolkit is introduced and explored in some detail. This is followed by a discussion of its implementation in Objective-C for iOS and Java for Android. A number of application scenarios are explored and the paper concludes with a general discussion of the technology and its potential impact for audio effects development.

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