Download A method for spectrum separation and envelope estimation of the residual in spectrum modeling of musical sound
We propose an original technique for separating the spectrum of the noisy residual component from that of the harmonic, quasideterministic one, and to estimate the envelope of the residual, for the spectrum modeling of musical sounds. The algorithm for spectrum separation relies on nonlinear transformations of the amplitude spectrum of the sampled signal (obtained via FFT), which allow to eliminate the dominant partials without the need for precisely tuned notch filters. The envelope estimation is performed by calculating the energy of the signal in the frequency domain, over a sliding time window. Eventually the residual can be obtained by combining its spectrum and envelope, so that separate processing can be performed on the two.
Download Transformation of instrumental sound related noise by means of adaptive filtering tecniques
In this work we present an extension of the classic schema of a time-varying filter excited with white noise for the modeling of noise signals from musical instrument sounds. The framework used is that of statistical signal processing, and a structure that combines an Autoregressive (AR) model with an adaptive FIR filter is proposed. A combbased structure for the AR filter is used when tuned noise is to be modeled. The analysis/resynthesis schema proposed is used to perform some basic sound transformations such as time stretching, tuning and energy envelop control, and spectral processing.
Download Realization of Vold-Kalman tracking filter. A least squares problem
The aim of this work was the implementation of the so-called VoldKalman filter. This filter was introduced by Vold and Leuridan in 1993 [1], it is a heterodyne filter for tracking the sinusoidal components of a noisy signal. The formulation of the Vold-Kalman filter leads to a least squares problem. The great advantage of this time-varying filter is that all sinusoids of a signal can be extracted simultaneously yielding a suppression of beating phenomena of close or crossing frequency trajectories. In this paper, we propose a realization for offline processing using the preconditioned conjugate gradient method. Furthermore, we present trivial expressions for the bandwidth and the transition time of first and second order filters.
Download A Java framework for FX development
This paper describes the first version of a Java archive (a term basically equivalent to ‘library’ in other programming languages) that has been developed and made available as public domain software for the benefit of the DAFX community, and the COSTG6 web pages in particular. The library is available both as source code and ready to run bytecodes. The archive defines an easy to use set of classes that are modelled after an effects processor. Ready made classes like ‘Effect’, ‘Page of Parameters’, ‘Integer Range Parameter’, ‘Real Range Parameter’, etc. serve as a basis to implement effects and share them. Effects can run from web pages or as stand alone applications, sharing unified look and feel in a platform independent graphical user interface. The programmer only needs to specify the parameters the effect will use, and the method (function) that will apply the effect to each new sample. An automatic GUI interface is created, that enables the adjustment of parameters as well as the specification of input and output files to be used during processing. Developing Java audio effects according to the proposed scheme will allow transparent integration into more complex multiband and multieffect architectures that will be added on a second version of the archive.
Download Digital waveguide networks for inhomogeneous media
Download A modular real-time PC-based audio processing tool for effect developers, engineers, musicians and educators
A modular real-time PC-based audio processing software tool has been developed which offers a high degree of user control, intended for use by audio effect developers, signal processing engineers, sound designers, musicians, and educators. The key technical features are described, followed by a range of example applications in the field of signal processing and audio effect design.
Download Monophonic transcription with autocorrelation
This paper describes an algorithm, which performs monophonic music transcription. A pitch tracker calculates the fundamental frequency of the signal from the autocorrelation function. A continuity-restoration block takes the extracted pitch and determines the score corresponding to the original performance. The signal envelope analysis completes the transcription system, calculating attack-sustain-decay-release times, which improves the synthesis process. Attention is also paid to the extraction of timbre and wavetable synthesis.
Download Extended performance techniques for a virtual instrument
In this paper we explore extended techniques for a physical model of a bowed string instrument controlled using the metasaxophone.
Download Continuous and discrete Fourier spectra of aperiodic sequences for sound modeling
The Fourier analysis of aperiodic ordered time structures related with number eight is considered. Recursion relations for the Fourier amplitudes are obtained for a sequence with discrete spectrum. The continuous spectrum of a different type of sequence is also studied . By increasing the number of points in the time axis dynamic spectra can be obtained and used for sound synthesis.
Download Modeling high-frequency modes of complex resonators using a waveguide mesh
This paper describes the use of a digital waveguide mesh which provides certain desirable components of the frequency response of the body of an instrument. An application for the violin is illustrated, showing that meshes can be designed to have a modal distribution which is psychoacoustically equivalent to the resonances of the violin body at high frequencies.