Method and apparatus for changing the relative positions of sound objects contained within a Higher-Order Ambisonics representation

摘要

Higher-order Ambisonics HOA is a representation of spatial sound fields that facilitates capturing, manipulating, recording, transmission and playback of complex audio scenes with superior spatial resolution, both in 2D and 3D. The sound field is approximated at and around a reference point in space by a Fourier-Bessel series. The invention uses space warping for modifying the spatial content and/or the reproduction of sound-field information that has been captured or produced as a higher-order Ambisonics representation. Different warping characteristics are feasible for 2D and 3D sound fields. The warping is performed in space domain without performing scene analysis or decomposition. Input HOA coefficients with a given order are decoded to the weights or input signals of regularly positioned (virtual) loudspeakers.

主权项

1. A method for changing the relative positions of sound objects contained within a two-dimensional or a three-dimensional Higher-Order Ambisonics (HOA) representation of an audio scene, wherein an input vector Ain with dimension Oin determines the coefficients of a Fourier series of the input signal and an output vector Aout with dimension Oout determines the coefficients of a Fourier series of the correspondingly changed output signal, said method comprising:
decoding said input vector Ain of input HOA coefficients into input signals sin in space domain for regularly positioned loudspeaker positions using a pseudo inverse of a mode matrix Ψ1 by calculatingsi⁢⁢n=ΨT⁡(Ψ⁢⁢ΨT)-1⁢Ai⁢⁢n;and
warping and encoding in space domain said input signals sin into said output vector Aout of adapted output HOA coefficients by calculating Aout=Ψ2sin, wherein the mode vectors of the mode matrix Ψ2 are modified with respect to the mode vectors of mode matrix Ψ1 according to a warping function ƒ(φ) by which the angles of the regularly positioned loudspeaker positions are one-to-one mapped into the target angles of the target loudspeaker positions in said output vector Aout.