Methods and apparatus for higher order ambisonics decoding based on vectors describing spherical harmonics

US10602293B2 · kind B2 · utility

Assignee

• Dolby International AB · IE

Inventors

• Holger Kropp · Großburgwedel, DE
• Stefan Abeling · Winsen (Aller), DE

Key dates

• Filing date: Mar 14, 2019
• Grant date: Mar 24, 2020
• Expiry date: Mar 14, 2039

Classification

• Technology area (CPC H): Electricity
• CPC primary: H04S2420/11
• WIPO field: Audio-visual technology
• WIPO sector: Electrical engineering

Abstract

The encoding and decoding of HOA signals using Singular Value Decomposition includes forming based on sound source direction values and an Ambisonics order corresponding ket vectors (|Y(Ωs)) of spherical harmonics and an encoder mode matrix (ΞOxS). From the audio input signal (|x(Ωs)) a singular threshold value (σs) determined. On the encoder mode matrix a Singular Value Decomposition is carried out in order to get related singular values which are compared with the threshold value, leading to a final encoder mode matrix rank (rfin). Based on direction values (Ωl) of loudspeakers and a decoder Ambisonics order (Nl), corresponding ket vectors (|Y(Ωl)) and a decoder mode matrix (ΨOxL) are formed. On the decoder mode matrix a Singular Value Decomposition is carried out, providing a final decoder mode matrix rank (rfin). From the final encoder and decoder mode matrix ranks a final mode matrix rank is determined, and from this final mode matrix rank and the encoder side Singular Value Decomposition an adjoint pseudo inverse (Ξ+)† of the encoder mode matrix (ΞOxS) and an Ambisonics ket vector (|a′s) are calculated. The number of components of the Ambisonics ket vector is reduced accordin…