Audio encoding device and method

Abstract

A method and a device (3) for encoding N audio signals, from N microphones (2) where N >= 3, are provided. For each pair of the N audio signals an angle of incidence of direct sound is estimated. A-format direct sound signals are derived from the estimated angles of incidence by deriving from each estimated angle an A-format direct sound signal. Each A-format direct sound signal is a first-order virtual microphone signal, for example, a cardioids signal.

Description

technical field [0001] The present invention relates to audio recording and encoding, and more particularly to virtual reality applications, especially provided by small portable devices. Background technique [0002] Virtual reality (VR) sound recording typically needs to be in Ambisonic B format and requires expensive directional microphones. Professional audio microphones can either record A format and encode it to Ambisonic B format, or record Ambisonic B format directly, such as with a sound field microphone. In general, the technical difficulty of VR lies in the deployment of omnidirectional microphones on mobile devices to capture sound. [0003] One way to generate a signal in ambisonic B-format, given an omnidirectional microphone distribution, is based on a differential microphone array, i.e., applying a delay and adding beamforming, to derive a first-order virtual microphone (e.g. cardioid) signal in A-format . [0004] The first limitation of this technique is...

AI Technical Summary

Problems solved by technology

The second disadvantage comes from the need for microphones in the high-end Ambisonic B format

[0008] The main limitation of these methods is the high number of microphones required

For consumer applications, due to the small number of microphones (typically up to 6), linear processing is too limited, resulting in signal to noise ratio (SNR) issues at low frequencies and aliasing at high frequencies

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