Context-Based Evaluation of the Opus Audio Codec for Spatial Audio Content in Virtual Reality

This paper discusses the evaluation of Opus-compressed Ambisonic audio content through listening tests conducted in a virtual reality environment. The aim of this studywas to investigate the effect that Opus compression has on the Basic Audio Quality (BAQ) of Ambisonic audio in different virtual reality contexts-gaming, music, soundscapes, and teleconferencing. The methods used to produce the test content, how the tests were conducted, the results obtained and their significance are discussed. Key findings were that in all cases, Ambisonic scenes compressed with Opus at 64 kbps/ch using Channel Mapping Family 3 garnered a median BAQ rating not significantly different than uncompressed audio. Channel Mapping Family 3 demonstrated the least variation in BAQ across evaluated contexts, although there were still some significant differences found between contexts at certain bitrates and Ambisonic orders.