A Hybrid Beamforming Framework For B-Format Encoding With Arbitrary Microphone Arrays

In this paper we consider the problem of B-format encoding of live audio scenes captured using practical compact microphone arrays with unconstrained microphone locations. We formulate the problem and provide a mathematical framework for a hybrid adaptive beamformer which combines active beamforming based on frequency-domain spatial analysis and synthesis for estimated directional audio sources and least-squares passive beamforming for residual audio scene components. The necessary calibration measurements are described and algorithmic details for efficient implementation are given.