Invention Grant
- Patent Title: Method and apparatus for higher order ambisonics encoding and decoding using singular value decomposition
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Application No.: US15676843Application Date: 2017-08-14
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Publication No.: US10244339B2Publication Date: 2019-03-26
- Inventor: Holger Kropp , Stefan Abeling
- Applicant: Dolby International AB
- Applicant Address: NL Amsterdam Zuidoost
- Assignee: Dolby International AB
- Current Assignee: Dolby International AB
- Current Assignee Address: NL Amsterdam Zuidoost
- Priority: EP13306629 20131128
- Main IPC: H04S3/00
- IPC: H04S3/00 ; H04S3/02 ; H04S7/00 ; G10L19/008

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 (ΞO×S). 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 (rfins). Based on direction values (Ωl) of loudspeakers and a decoder Ambisonics order (Nl), corresponding ket vectors (|Y(Ωl)) and a decoder mode matrix (ΨO×L) are formed. On the decoder mode matrix a Singular Value Decomposition is carried out, providing a final decoder mode matrix rank (rfind). 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 (ΞO×S) and an Ambisonics ket vector (|a′s) are calculated. The number of components of the Ambisonics ket vector is reduced according to the final mode matrix rank so as to provide an adapted Ambisonics ket vector (|a′l). From the adapted Ambisonics ket vector, the output values of the decoder side Singular Value Decomposition and the final mode matrix rank an adjoint decoder mode matrix (Ψ)† is calculated, resulting in a ket vector (|y(Ωl)) of output signals for all loudspeakers.
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