DAFx-15 Proceedings

  • Proceedings of the 18th International Conference
    on Digital Audio Effects

    DAFx cover

    November 30 — December 3, 2015
    Trondheim, Norway

  • The complete proceedings in a single pdf here (64,6 Mb). Individual papers accessible below. Please report any errors.

All copyrights remain with the authors.

  • Keynotes

  • Marije Baalman: Digital audio out of the box - digital audio effects in art and experimental music

    While since the late 1990's laptops have become a common element in electronic music on stage, in recent years there is a move away again from the laptop, towards dedicated devices that perform one particular task. With the advent of platforms such as the BeagleBone, Raspberry Pi, but also Arduino, efficient computing of digital audio has found a large interest amongst artists who create their own instruments or sounding objects, usually within the context of open source software and hardware.

    In this talk I will show various examples of these applications of digital audio in the field of art and experimental music; and discuss how their development and discourse is embedded in the open source movement.

  • Julius Smith & Kurt Wegner: Recent Progress in Wave Digital Audio Effects

    The digital audio effects (DAFx) community has contributed significantly to advancements in ``virtual analog'' modeling of classic audio effects in software.  Practicing musicians have enjoyed a growing list of classic analog gear available now as digital audio plugins as a result.

    One competitive approach is the Wave Digital Filters (WDF) formulation pioneered by Alfred Fettweis. WDFs have been around since the early 1970s and have found much use in VLSI implementations of digital filters, where superior numerical robustness is especially important.  Since the early 2000s, this framework has been applied increasingly to musical acoustic modeling and digital audio effects, and its range of applicability has been recently expanded considerably to include arbitrary circuit topologies and multiple nonlinear elements.

    The closely-related Digital Waveguide Framework (DWF) similarly uses wave variables (traveling-wave components) because wave-propagation delay lines can be implemented super efficiently as circular buffers.  As a result, it is straightforward to combine these two paradigms to yield wave-variable models of a mixture of distributed and lumped systems, such as a lumped hammer model striking waveguide string in the case of a piano model.

    WDFs use wave variables in the context of lumped modeling where, by definition, wave propagation does not occur. How then can we understand the use of wave variables in WDFs?  This talk includes a somewhat alternative development of WDF principles based on the way that wave variables can be used to resolve implicit relationships in modular discrete circuit models.

    The complexity of audio circuitry has often stressed the state of the art of WDFs, especially for nonlinear models. The DAFx community has contributed many new techniques in response.  This talk will review these contributions and point out remaining issues for future research in WDF theory.

    In addition to their theoretical appeal, desirable energetic/numerical properties, and fine-grained modeling fidelity, WDFs are also attractive to virtual-analog algorithm designers as an elegant modular software framework. Implementing WDFs as a hierarchical object-orient tree in software such as C++ can yield readable and reusable code, with clear high-level descriptions of circuits and digital audio processing. We include examples of practical wave digital modeling, and demonstrations of real-time performance.

  • Franz Zotter: Ambisonic Audio Effects in Direction and Directivity

    The properties of the spherical harmonics to represent patterns on the sphere, as well as their deep embedding in the acoustical wave equation, enable many nice audio effects in space.

    First of all, the inherent smoothness of the finite-order spherical harmonic representations is the basis of Ambisonic amplitude panning on surrounding loudspeakers. The spherical harmonic representation is mighty enough to represent several directional effects, such as mirroring, rotation, directional loudness manipulation, directional warping in terms of a simple matrix multiplication.

    What is more, the associated acoustic equations permit design and signal processing of not only microphone arrays for Ambisonic recording, but also spherical loudspeaker arrays for directivity synthesis.

    The plenary lecture gives examples and explanations of freely available Plugins for Ambisonics (VST AmbiX plugin suite), and reveals a peek on adjustable directivity as a musical instrument.

  • Tutorials

  • Peter Svensson: Sound field modeling for virtual acoustics

    The terms virtual acoustics and auralization have been used for around 20 years for the generation of computer simulations of sound fields that can be listened to. This tutorial will give a brief overview over the components involved: the source modeling, the modeling of an environment via an impulse response, and the rendering stage. The focus will be on the modeling og environments, with the categories of physical modeling and perceptual modeling. Furthermore, the physical modeling can be done by accurately solving the wave equation, or by geometrical-acoustics based methods. Possibilities and limitations with these methods will be discussed, demonstrating the various reflection components of specular reflection, diffuse reflection, and diffraction. Examples will be shown using the author’s Matlab “Edge diffraction toolbox” for generating animations of these phenomena.

  • Øyvind Brandtsegg & Trond Engum: Cross-adaptive effects and realtime creative use

    Adaptive effects and modulations have been researched during the last two decades within the DAFx community, and cross-adaptive effects have been utilized for autonomous mixing and related applications. Current research into cross adaptive effects for creative use in realtime applications has led to the development of methods to incorporate these techniques into regular DAWs for audio production and performance. The tutorial will give insight into these methods, with practical examples on how to incorporate the tools in a DAW based workflow. Examples of use within live performance will also be presented.

  • Xavier Serra: The AudioCommons Initiative and the technologies for facilitating the reuse of open audio content

    Significant amounts of user-generated audio content, such as sound effects, musical samples and music pieces, are uploaded to online repositories and made available under open licenses. Moreover, a constantly increasing amount of multimedia content, originally released with traditional licenses, is  becoming public domain as its license expires. Nevertheless, this content is not much used in professional productions. There is still a lack of familiarity and understanding of the legal context of all this open content, but there are also problems related with its accessibility. A big percentage of this content remains unreachable either because is not published online or because it is not well organised and annotated. With the Audio Commons Initiative we want to promote the use of open audio content and to develop technologies with which to support the ecosystem composed by content repositories, production tools and users. These technologies should enable the reuse of this audio material, facilitating its integration in the production workflows used by the creative industries. In this workshop we will go over the core ideas behind this initiative, then overview the existing audio repositories, technologies and production tools related to it, and finally outline the planned tasks to address the challenges posed by the initiative.