Spatial noise filling in multi-channel codec

A method of generating background noise ambience in a multi-channel codec, the method comprising:

• computing, with at least one processor, from a primary downmix channel generated from an input multi-channel audio signal representing a spatial audio scene with background noise ambience, noise estimates of noise in the primary downmix channel;
• computing, with the at least one processor, spectral shaping filter coefficients based on the noise estimates;
• spectrally shaping, with the at least one processor, a multi-channel noise signal using the spectral shaping filter coefficients and a noise distribution, the spectral shaping resulting in a diffused, multi-channel noise signal with uncorrelated channels;
• spatially shaping, with the at least one processor, the diffused, uncorrelated multi-channel noise signal with uncorrelated channels based on a noise ambience of the spatial audio scene;
• and
• outputting, with the at least one processor, the spatially and spectrally shaped multi-channel noise signal to synthesize the background noise ambience of the spatial audio scene.