Apparatus, method and computer program for encoding, decoding, scene processing and other procedures related to DirAC based spatial audio coding using low-order, mid-order and high-order components generators

A method for generating a sound field description using an input signal comprising a mono-signal or a multi-channel signal, comprising:

• analyzing the input signal to derive direction data and diffuseness data;
• generating a low-order sound field description from the input signal up to a predetermined order and mode, wherein the generating the low-order sound field description comprises deriving the low-order sound field description by copying the input signal or performing a weighted combination of the channels of the input signal;
• generating a mid-order sound field description above the predetermined order or at the predetermined order and above the predetermined mode and below a high order using a synthesis of at least one direct portion and of at least one diffuse portion using the direction data and the diffuseness data so that the mid-order sound field description comprises a direct contribution and a diffuse contribution;
• and
• generating a high-order sound field description comprising a component at or above the high order using a synthesis of at least one direct portion without any diffuse component synthesis so that the high-order sound field description comprises a direct contribution only.

A non-transitory digital storage medium having a computer program stored thereon to perform, when said computer program is run by a computer, the method for generating a sound field description using an input signal comprising a mono-signal or a multi-channel signal, the method comprising:

• analyzing the input signal to derive direction data and diffuseness data;
• generating a low-order sound field description from the input signal up to a predetermined order and mode, wherein the generating the low-order sound field description comprises deriving the low-order sound field description by copying the input signal or performing a weighted combination of the channels of the input signal;
• generating a mid-order sound field description above the predetermined order or at the predetermined order and above the predetermined mode and below a high order using a synthesis of at least one direct portion and of at least one diffuse portion using the direction data and the diffuseness data so that the mid-order sound field description comprises a direct contribution and a diffuse contribution;
• and
• generating a high-order sound field description comprising a component at or above the high order using a synthesis of at least one direct portion without any diffuse component synthesis so that the high-order sound field description comprises a direct contribution only.