Download Real-Time Partial Tracking in an Augmented Additive Synthesis System This paper describes an approach to real time partial tracking in an analysis\transformation\resynthesis system using a combination of linear and bi-linear time-frequency techniques. Tests of the system have been made using both natural and synthetic sounds. Results are presented and areas for further research and development are discussed.
Download Real time spectral expansion for creative and remedial sound transformation In this paper we describe the implementation, use and applications of WaveThresh, a real time Fourier\wavelet spectral expander. Expansion and reverse-expansion of spectral components is offered. In order that analysis methods can be better adapted to the signal we offer a combined wavelet\Fourier mode. This mode separates sinusoids from the rest of the signal (residual) and applies Fourier analysis to the sinusoids and wavelet analysis to the residual.
Download High Accuracy Frame-by-Frame Non-Stationary Sinusoidal Modelling This paper describes techniques for obtaining high accuracy estimates, including those of non-stationarity, of parameters for sinusoidal modelling using a single frame of analysis data. In this case the data used is generated from the time and frequency reassigned short-time Fourier transform (STFT). Such a system offers the potential for quasi real-time (frame-by-frame) spectral modelling of audio signals.
Download Short-Time Wavelet Analysis of Analytic Residuals for Real-Time Spectral Modelling This paper describes an approach to using compactly supported spline wavelets to model the residual signal in a real-time (frameby-frame) spectral modelling system. The outputs of the model are time-varying parameters (gain, centre frequency and bandwidth) for filters which can be used in a subtractive resynthesis system.
Download Two‐Dimensional Fourier Processing of Rasterised Audio There is continuous research effort into the expansion and refinement of transform techniques for audio signal processing needs, yet the two-dimensional Fourier transform has seldom been applied to audio. This is probably because audio does not readily allow the application of a 2D transform, unlike images for which its use is common. A signal mapping is first required to obtain a two-dimensional representation. However the 2D Fourier transform opens up potential for new or improved analysis and transformation of audio. In this paper, raster scanning is used to provide a simple mapping between one- and two-dimensional representations. This allows initial experimentation with the 2D Fourier transform, in which the 2D spectrum can be observed. A straightforward method is used to display the spectral data as a colour image. The transform gives information on two frequency axes, one in the typical audible frequency range and the other in the low frequency rhythmic range. This representation can be used to more easily observe rhythmic modulations in the signal. Some novel audio transformations are presented, allowing manipulation of rhythmic frequency content. The techniques developed using the 2D Fourier transform allow interaction with audio in a new domain, both analytically and creatively. This work shows how two common signal processing mechanisms can be combined to exciting effect for audio applications.
Download A Scalable Architecture for General Real-Time Array-Based DSP on FPGAs with Application to the Wave Equation This paper describes a scheme for parallel execution on FPGAs of DSP tasks which rely heavily on MAC operations. Multiple operations are assigned to a single ‘processing node’ such that each node can operate just in real-time. Where the number of MACs required exceeds the capability of a single processing node additional nodes are added until the capacity of the FPGA is exhausted. Additional requirements beyond the capability of a single FPGA are accommodated by extension across multiple devices, offering significant scalability. Resource usage, performance results for an example acoustic modelling application on a modest single FPGA and development system are presented.