Flexible data structures for dynamic virtual auditory scenes

Abstract

Virtual environments and their contents are dynamically changing, but also need to respond to the user immediately. While managing a dynamic scene is a common and well-understood problem for visual rendering, additional challenges exist for the high-quality audio rendering of such scenes. Audio rendering differs in a key aspect: Sound waves propagate substantially slower than light. For the acoustics in scenes of large dimensions, it is not sufficient to regard just the state at the current time. The sound propagation times become so significant (perceptible) that the past of the objects matter, making a time history of the scene necessary. Particularly the conjunction of multithreading and low-latency audio processing makes the description of the virtual acoustic scene a problem on its own. This paper presents a novel solution to this acoustic-related problem. We discuss the challenges of realizing a real-time auralization on modern (non-real-time) operating systems and state the main requirements of the data structure. A hierarchical state-based data structure with time history is presented, which not only fulfills the requirements for outdoor auralizations but also has key advantages for indoor simulations—such as room acoustics. A key feature is the integral support of atomic scene modifications, allowing several modifications to be performed at the same time. The presented concept is very modular and beneficial for a wide range of applications.