Download Instrument reusability scheme in PWGLSynth
This paper presents our recent developments that aim to make the instrument definition process of our visual synthesis environment more accessible to a broader audience. There are several novel aspects that aim to overcome some of the classical limitations found in sound synthesis systems. After an introductory section we discuss two advanced examples where scores containing several model-based instrument parts can be realized without having to edit the original instrument definitions. In the first one, we can duplicate instrumental parts of a single instrument definition. In the latter example, we can mix in a single score several instrument models with the help of a mixer patch that is automatically created by system.
Download Audio synthesis by bitwise logical modulation
The synthesis of rich audio spectra requires usually complex source waveforms, a large number of simple source components, or increased algorithmic complexity. This paper describes an implementation, which shows that simple elementary bitwise logical operations (OR, AND, XOR) possess power to produce such spectra. Applying these operations to two sinusoidal audio oscillators produced wide variety of new harmonically related sonic material. The synthesis method is efficient to implement and easily controllable, but it is not generally band-limited.
Download Score level timbre transformations of violin sounds
The ability of a sound synthesizer to provide realistic sounds depends to a great extent on the availability of expressive controls. One of the most important expressive features a user of the synthesizer would desire to have control of, is timbre. Timbre is a complex concept related to many musical indications in a score such as dynamics, accents, hand position, string played, or even indications referring timbre itself. Musical indications are in turn related to low level performance controls such as bow velocity or bow force. With the help of a data acquisition system able to record sound synchronized to performance controls and aligned to the performed score and by means of statistical analysis, we are able to model the interrelations among sound (timbre), controls and musical score indications. In this paper we present a procedure for score-controlled timbre transformations of violin sounds within a sample based synthesizer. Given a sound sample and its trajectory of performance controls: 1) a transformation of the controls trajectory is carried out according to the score indications, 2) a new timbre corresponding to the transformed trajectory is predicted by means of a timbre model that relates timbre with performance controls and 3) the timbre of the original sound is transformed by applying a timevarying filter calculated frame by frame as the difference of the original and predicted envelopes.
Download Improved control for selective minimization of masking using inter-channel dependancy effects
A digital audio effect for real time mixing applications, which dynamically adapts to the multi-channel input, has been implemented. The resulting audio mix is the direct result of the analysis of the content of each individual channel with respect to the other channels. The implementation permits the enhancement of a source with respect to the rest of the mixture by selectivity unmasking its spectral content from spectrally related channels. A masking measurement has also been implemented in order to measure the efficiency of the algorithm.
Download Coefficient-modulated first-order allpass filter as distortion effect
A novel approach to implement the distortion effect is introduced. The proposed approach is based on time-varying phase distortion of the input signal, and it is implemented using a coefficient modulated first-order allpass filter. This new technique provides control over the distorted band with a proper choice of the modulating signal. By choosing a modulating signal that applies the phase distortion only for low frequencies, the aliasing often generated by conventional distortion effects, which modify the signal amplitude, can be greatly reduced. Modulation signals that produce distortion effects applicable for electric guitar playing are also discussed. Sound examples on the use of the filter can be found at Papers/dafx08/.
Download Nonlinear modeling of a guitar loudspeaker cabinet
Distortion is a desirable effect for sound coloration in electric guitar amplifiers and effect processors. At high sound levels, particularly at low frequencies, the loudspeakers used in classic style cabinets are also a source of distortion. This paper presents a case study of measurements and digital modeling of a typical guitar loudspeaker as a real-time audio effect. It demonstrates the complexity of the driver behavior, which cannot be efficiently modeled in true physical detail. A model with linear transfer functions and static nonlinearity characteristics to approximate the measured behavior is derived based upon physical arguments. An efficient method to simulate radiation directivity is also proposed.
Download Inverting dynamics compression with minimal side information
Dynamics processing is a widespread technique, both at music production and diffusion stages. In particular, dynamic compression is often used in such a way that the “average” listener can best enjoy the music. However, this may lead to an excessive use of compression, especially with respect to listeners in quiet listening conditions. This paper presents estimates on the amount of extra data that is needed to invert the effects of such non-linear processing, using simple blind identification techniques. We present two simple test cases, first in the case when perfect reconstruction is needed, and second when the ancillary data rate is constrained, leading to an approximate reconstruction.
Download Time and pitch scale modification: A real-time framework and tutorial
A framework is presented which is designed to address the issues related to the real-time implementation of time-scale and pitchscale modification algorithms. This framework can be used as the basis for the developments of applications which allow for a seamless real-time transition between continually varying timescale and pitch-scale parameters which arise as a result of manual or automatic intervention.
Download Improved hidden Markov model partial tracking through time-frequency analysis
In this article we propose a modification to the combinatorial hidden Markov model developed in [1] for tracking partial frequency trajectories. We employ the Wigner-Ville distribution and Hough transform in order to (re)estimate the frequency and chirp rate of partials in each analysis frame. We estimate the initial phase and amplitude of each partial by minimizing the squared error in the time-domain. We then formulate a new scoring criterion for the hidden Markov model which makes the tracker more robust for non-stationary and noisy signals. We achieve good performance tracking crossing linear chirps and crossing FM signals in white noise as well as real instrument recordings.
Download Two-step modal identification for increased resolution analysis of percussive sounds
Modal synthesis is a practical and efficient way to model sounding structures with strong resonances. In order to create realistic sounds, one has to be able to extract the parameters of this model from recorded sounds produced by the physical system of interest. Many methods are available to achieve this goal, and most of them require a careful parametrization and a post-selection of the modes to guarantee a good quality/complexity trade-off. This paper introduces a two step analysis method aiming at an automatic and reliable identification of the modes. The first step is performed at a global level with few assumptions about the spectro/temporal content of the considered signal. From the knowledge gained with this global analysis, one can focus on specific frequency regions and perform a local analysis with strong assumptions. The gains of such a two step approach are a better estimation of the number of modal components as well as a better estimate of their parameters.