Download A hybrid approach to timbral consistency in a virtual instrument
The aim of this work is to make an instrument that is timbrally consistent over pitch and loudness. This particular work is not attempting to reproduce an existing instrument’s timbre, but to produce a timbrally dynamic virtual instrument that can be designed by the user. In this paper there is a brief introduction to timbre and synthesis methods, followed by a proposal on how to make timbrally consistent virtual instruments out of given timbres.
Download Multichannel audio decorrelation for coding
Within digital audio codification, the processing of multichannel signals has become one of the main fields of research. Current work on the subject look for effective ways to exploit the existing redundancy between the different channels in order to reduce the codification binary rate. This work studies the Karhunen-Loeve Transform (KLT) as a method of decorrelating multi-channel signals prior to coding. Results on codification via AAC are reported.
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 FFT analysis as a creative tool in live performance
This paper describes the use of real time spectral analysis to enhance the creative opportunities in improvised live electronics/instrumental performance. FFT analysis allows musicians to observe in performance a visual representation of the spectrum, displaying the spectral characteristics of audio resulting from performance activity and/or computer processing. These characteristics can then be explored during performance, assigning areas of special interest within the spectrum to parameters which in turn control (or at least influence) electronic processing. This creates an effective, easily manipulated but potentially highly complex performance environment, encouraging further interaction between improvising performers, and allowing subtle and complex links to emerge between the timbral features of actual music (result) and the act of performance (cause). We hope to increase awareness of the performance-specific potential of familiar analytical tools, of which FFT is one example, and their unfulfilled creative potential.
Download Recent developments in PWSYNTH
PWSynth was originally a visual synthesis language situated in PatchWork. Recently our research team has started a complete rewrite of the system so that it can be adapted to our new programming environment called PWGL. In this paper we present the main differences of the old and new systems. These include switching from C to C++, efficiency issues, interface between PWGL and the synthesis engine, and a novel copy-synth-patch scheme.
Download Model-based event labeling in the transcription of percussive audio signals
In this paper we describe a method for the transcription of percussive audio signals which have been performed with arbitrary nondrum sounds. The system locates sound events from the input signal using an onset detector. Then a set of features is extracted from the onset times. Feature vectors are clustered and the clusters are assigned with labels which describe the rhythmic role of each event. For the labeling, a novel method is proposed which is based on metrical (temporal) positions of the sound events within the measures. The system is evaluated using monophonic percussive tracks consisting of non-drum sounds. In simulations, the system achieved a total error rate of 33.7%. Demo signals are available at URL:<http://www.cs.tut.fi/~paulus/demo/>.
Download Estimation of tempo, micro time and time signature from percussive music
Tempo, micro time and time signature are basic rhythmic features for a wide range of music. Their automated extraction from music is needed for a number of applications, e.g. automatic transcription and music information retrieval systems, authoring tools, entertainment applications, musicological analysis or educational purposes. The presented analysis procedure estimates tempo, micro time and time signature from percussive music. From 117 excerpts of eight seconds length, 84.6% of the tempo values, 83.8% of the micro time and 73.5% of the time signatures were estimated correctly.
Download Complex domain onset detection for musical signals
We present a novel method for onset detection in musical signals. It improves over previous energy-based and phase-based approaches by combining both types of information in the complex domain. It generates a detection function that is sharp at the position of onsets and smooth everywhere else. Results on a handlabelled data-set show that high detection rates can be achieved at very low error rates. The approach is more robust than its predecessors both theoretically and practically.
Download Rhythmic expressiveness transformations of audio recordings: swing modifications
In this paper, we propose a computer software for modifying rhythmic performances of polyphonic musical audio signals. It first describes the rhythmic content of an audio signal (i.e. determination of tempi and beat indexes at the quarter-note and eighth-note levels, as well as estimation of the swing ratio). Then, the signal is transformed in real-time using a time-stretch algorithm. We present basic techniques provided by commercial products for swing modification and compare these to our system.