Engineering Brief
Developing a Binaural Renderer for Audio Definition Model Content
AES Convention 152 · Paper 668 · May 2022
Abstract
The Audio Definition Model (ADM) can be used to represent object- and scene-based audio programmes, and there is a standardised method for reproducing ADM content on loudspeakers, but not currently for headphones. We present the design and implementation of a binaural renderer for the ADM, which supports the features of the ADM while maintaining high-quality output. For rendering objects the system uses virtual loudspeaker rendering with windowed binaural room impulse responses (BRIRs). To reduce comb-filtering effects, delay is removed from the BRIRs and replaced with a per-ear and per-object variable fractional delay line. When rendering diffuse sources, the original delays are used, as the varied onset delays help create perceived extent. The overall gain of each source is adjusted dynamically to compensate for loudness changes caused by interactions between BRIRs of neighbouring loudspeakers. The system is available as an open-source C++ library based on the VISR framework, suitable for adding real-time head-tracked binaural output to applications, and is built into the EAR Production Suite.
