Session Chair: Kerry Hagan
Paper abstracts
Alexandre Francois: “Real-Time, Low-Latency, High Resolution Audio Spectral Analysis: Phase Matters”
This paper introduces an original approach to computing a spectral representation of audio signals, with high temporal and frequency resolution and high amplitude accuracy, in real-time and with low latency. Applying techniques from phase vocoders to make use of phase information, a new tracking resonator model extends the original Resonate model while retaining its iterative formulation and computational efficiency. A bank composed of frequency tracking resonators constantly self-tunes to the contents of the input signal, rendering the precise tuning of the resonators irrelevant, as long as the bank offers an appropriate coverage of the frequency range of interest for the target application. Self-tuning banks form the basis for an analysis technique that produces, in real-time, for each input sample, a list of uniquely identified and precisely tracked frequency components present in the input signal, together with their correct amplitudes. High temporal and frequency resolution spectrograms illustrate the spectral analysis of real musical signals in a familiar format. The detailed representations produced can potentially improve the quality and accuracy of any traditional application. They also offer promising prospects for real-time, low-latency applications such as accompaniment and improvisation systems. Encouraging initial synthesis experiments also motivate further investigation.
Robert Esler: “Pd++: A C++ Library of Pure Data’s DSP Objects”
Pd++ is a real-time C++ audio synthesis library that implements Pure Data’s DSP (digital signal processing) objects as C++ classes, making it usable with object-oriented programming languages like C++, Java, or C#. The library has been designed to follow similar logic and naming conventions of Pure Data. It includes bindings for Java which allows the library to work with the Processing development environment and C# providing a native code interface to the Unity game engine. Pd++ has also been extensively tested on all major operating systems including iOS and Android, single board CPUs like the Raspberry Pi, as well as C++ based Application Programming Inter- faces (APIs) such as Unreal Engine, Wwise, JUCE and FMOD. In this article the author presents how the library works in design, practice and philosophy, its perceived workflow as a design and educational tool, as well as future developments for Pd++.
Jeremy Hyrkas: “Vibrato Matching for Modulation Control and Blending in Sound Mixtures”
In sound mixtures of more than one musical source, different vibrato patterns act as a cue that multiple sources are present for both human listeners and source separation algorithms. Matching the vibrato patterns of the signals in the mixture reduces the perception of multiple sources, particularly when the sources play in unison. This work introduces the vibrato matching algorithm, which first suppresses vibrato in a target signal and then transfers vibrato from a source signal to the target. An existing vibrato suppression algorithm is combined with a new algorithm for vibrato transfer, which imparts frequency modulation and amplitude modulation to the harmonics of the target signal, and amplitude modulation onto the spectral envelope of the non-harmonic residual component. Examples demonstrate the algorithm’s utility as a vibrato control mechanism and as a tool for blending sound sources. Matching vibrato degrades the performance of source separation algorithms, suggesting a similar degradation in listeners ability to detect the presence of multiple sources.
