A modular, A2B-based architecture for distributed multichannel full-digital audio systems

Abstract

In this work, a new architecture for audio signal distribution is presented. Immersive audio recording and reproduction systems require more and more channels, and consequently the cost and the complexity of these systems increases too. The goal of this work is to present an audio distribution architecture that allows simplifying the cabling and the complexity of multichannel systems composed by a great number of transducers. Even though, most of today’s systems adopt audio-over-ethernet or audio-over-IP technologies, the Automotive Audio Bus (A2B) is a promising solution to implement the front-end section of the data transport architecture. In fact, it is a low-cost and simple technology that is based on nodes connected in daisy-chain, and on the same bus, audio data, configuration commands, and power are transported together. Moreover, A2B offers great performance: low-jitter, and just 2 samples of latency. However, it also presents some limitations due to the static configuration of the bus and to the limited cable length. These shortcomings were overcome by the adoption of longer-range protocols to communicate with existing systems and by the introduction of a new A2B feature called A2B Plug-and-Play, which allows dynamically connecting and disconnecting different devices on the bus. The proposed architecture is composed by three main parts: the peripheral devices, the transport layer, and the processing and protocol conversion section. The peripheral devices are A2B enabled systems of any kind (e.g., amplifiers, microphones, processing units, etc.). Some examples are presented in the case studies section of this dissertation. The processing and protocol conversion section is implemented by a custom board called A2B-DSP. In the last chapter of this dissertation, three case studies that leverage the proposed architecture are presented, namely the audio distribution in a car, a Wave Field Synthesis (WFS) listening room and three types of microphone arrays.