AUDIENCE for Pd, a scene-oriented library for spacial audio
Author: Regis Faria
Download full paper: Media:AUDIENCE for Pd a scene-oriented library for spacial audio.pdf
AUDIENCE for Pure Data is a library for audio immersion, sound scene production and auralization. The software enables to work independently the sound scene composition, its acoustic rendering, encoding it in a suitable multichannel format, and finally auralizing it using 2D or 3D sound fields. A major feature of it is the sound scene conception independence from the listening mode, as the user can work out a desired sound scene spatial experience regardless of the loudspeaker configuration used to listen. The AUDIENCE library distribution is organized in 12 directories containing the main spatial processing layers (L1, L2, L3, L4), an auxiliary functions layer, reference applications, supportive libraries, binaries, images and sounds, test patches and documentation. Externals are compiled to MAC OS, Linux and Win32. A typical project flow involves creating a sound scene (layer 1 object), configuring an acoustic rendering scheme (layer 2 object), encoding the spatial sound of the rendered scene (layer L3 object) and then decoding and auralizing the sound scene through a loudspeaker rig (layer 4 object). Auxiliary functions, such as transport, mixing and volume controls are available from objects in the auxiliary layer. The full distribution version 2.0.2 supports a scalable interactive sound scene graphical user interface, Ambisonics (up to the 3rd order) and MPEG-4 AAC codecs, image-source-based acoustic simulation, multichannel recording and playing (including 5.1) and it can decode to 10 different speaker layouts. Currently a new acoustic simulator with ray-tracing and radiosity support, loudness management and object-oriented timeline features are under development. The architecture is scalable: many scenes and sound sources can be combined, while real time interaction placing and moving objects in the scenes is possible. The final sound field can be exported and played back in stereo and surround output formats. AUDIENCE and its open version OpenAUDIENCE are been developed collaboratively since 2005 , and have been used in several scientific and artistic projects since then. In 2007 it was used to spatialize the piece “The Unanswered Question” by Charles Ives (1906) with 9 instruments (a string quartet, a wind quartet and a trumpet). In the same year its underlying architecture was proposed as framework for the new MPEG SAOC codec. In 2009 the electro-acoustic piece “Kitchen” by Fernando-Lopez Lezcano, with 8 sound sources, was spatialized during the SBCM 2009 symposium in Recife. AUDIENCE is presently employed as auralization engine in a CAVE system at the University of São Paulo, and has been further used as reference audio engine for reconfigurable digital music applications, soundscape design applications and scene-oriented mixing. The system development is going to its 3rd. generation, designing improvements in the usability and sound fidelity, expanding the number of spatial processing functions, and looking forward to enlarging its platform availability to prospecting new applications and user groups.
- at the Audio Engineering and Coding Center (NEAC) in the University of São Paulo
- Spatial Audio Object Coding
4th international Pure Data Convention 2011 Weimar ~ Berlin