Method and apparatus for generating 3D audio content from two-channel stereo content

Patent metadata

Field	Value
Publication number	US-10448188-B2
Application number	US-201615761351-A
Country	US
Kind code	B2
Filing date	Sep 29, 2016
Priority date	Sep 30, 2015
Publication date	Oct 15, 2019
Grant date	Oct 15, 2019

Abstract

For generating 3D audio content from a two-channel stereo signal, the stereo signal (x(t)) is partitioned into overlapping sample blocks and is transformed into time-frequency domain. From the stereo signal directional and ambient signal components are separated, wherein the estimated directions of the directional components are changed by a predetermined factor, wherein, if changes are within a predetermined interval, they are combined in order to form a directional center channel object signal. For the other directions an encoding to Higher Order Ambisonics (HOA) is performed. Additional ambient signal channels are generated by de-correlation and rating by gain factors, followed by encoding to HOA. The directional HOA signals and the ambient HOA signals are combined, and the combined HOA signal and the center channel object signals are transformed to time domain.

First claim

The invention claimed is:

1. A method for determining 3D audio scene and object based content from two-channel stereo based content represented by a plurality of time/frequency (T/F) tiles, comprising:
determining, for each T/F tile, ambient power, direct power, source direction φ S ({circumflex over (t)}, k) and mixing coefficients;
determining, for each tile, a directional signal and two ambient T/F channels based on the corresponding ambient power, direct power, and mixing coefficients; and
determining the 3D audio scene object based content based on the directional signal and ambient T/F channels of the T/F tiles further including:
calculating for each tile in Time/Frequency (T/F) domain a correlation matrix

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 with E( ) denoting an expectation operator;
calculating Eigenvalues of C({circumflex over (t)}, k) by:
λ 1 ( {circumflex over (t)}, k )=1/2( c 22 +c 11 +√{square root over (( c 11 −c 22 ) 2 +4| c r12 | 2 )})

λ 2 ( {circumflex over (t)}, k )=1/2( c 22 +c 11 −√{square root over (( c 11 −c 22 ) 2 +4| c r12 | 2 )}),

with c r12 =real(c 12 ) denotes the real part of c 12 ;
calculating from C({circumflex over (t)}, k) estimations P N ({circumflex over (t)}, k) of ambient power P N ({circumflex over (t)}, k)=λ 2 ({circumflex over (t)}, k), estimations P s ({circumflex over (t)}, k) of directional power P s ({circumflex over (t)}, k)=λ 1 ({circumflex over (t)}, k)−P N ({circumflex over (t)}, k), elements of a gain vector a({circumflex over (t)}, k)=[a 1 ({circumflex over (t)}, k), a 2 ({circumflex over (t)}, k)] T that mixes directional components into x({circumflex over (t)}, k) and which are determined by:

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Assignees

• Dolby Laboratories Licensing Corp

Inventors

• Boehm Johannes
• Chen Xiaoming

Classifications

• H04S5/00 Primary

  Pseudo-stereo systems, e.g. in which additional channel signals are derived from monophonic signals by means of phase shifting, time delay or reverberation · CPC title

• H04S7/30

  Control circuits for electronic adaptation of the sound field · CPC title

• H04S2400/05

  Generation or adaptation of centre channel in multi-channel audio systems · CPC title

• H04S7/302 Primary

  Electronic adaptation of stereophonic sound system to listener position or orientation (H04S7/301 takes precedence) · CPC title

• H04S2400/11

  Positioning of individual sound objects, e.g. moving airplane, within a sound field (H04S2420/13 takes precedence) · CPC title