An audio decoder for providing at least four audio channel signals on the basis of an encoded representation is configured to provide a first residual signal and a second residual signal on the basis of a jointly encoded representation of the first residual signal and of the second residual signal using a multi-channel decoding. The audio decoder is configured to provide a first audio channel signal and a second audio channel signal on the basis of a first downmix signal and the first residual signal using a residual-signal-assisted multi-channel decoding. The audio decoder is configured to provide a third audio channel signal and a fourth audio channel signal on the basis of a second downmix signal and the second residual signal using a residual-signal-assisted multi-channel decoding. An audio encoder is based on corresponding considerations.

Examples of the disclosure relate to apparatus, methods and computer programs for processing spatial audio to reduce the effects of errors within the spatial audio. The apparatus can be configured to obtain spatial audio and associated one or more three-dimensional parameters wherein the one or more three-dimensional parameters comprise one or more direction parameters. The apparatus can also be configured to determine one or more ranges for direction parameters when the one or more three-dimensional parameters are reduced to two dimensions to obtain one or more two-dimensional parameters. The apparatus can also be configured to apply processing to the one or more two-dimensional parameters based on whether or not the one or more ranges in two dimensions are in accordance with one or more criteria.

An apparatus including at least one processor and at least one memory including a computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: determine, for two or more microphone audio signals, at least one spatial audio parameter for providing spatial audio reproduction; determine at least one coherence parameter associated with a sound field based on the two or more microphone audio signals, such that another sound field is configured to be reproduced based on the at least one spatial audio parameter and the at least one coherence parameter.

An audio signal processing method and apparatus for adaptively adjusting a decorrelator. The method comprises obtaining a control parameter and calculating mean and variation of the control parameter. Ratio of the variation and mean of the control parameter is calculated, and a decorrelation parameter is calculated based on the said ratio. The decorrelation parameter is then provided to a decorrelator.

An apparatus and method of rendering audio. A binaural signal is split on an amplitude weighting basis into a front binaural signal and a rear binaural signal, based on perceived position information of the audio. In this manner, the front-back differentiation of the binaural signal is improved.

An encoding system encodes an N-channel audio signal (X), wherein N≥3, as a single-channel downmix signal (Y) together with dry and wet upmix parameters ({tilde over (C)}, {tilde over (P)}). In a decoding system, a decorrelating section outputs, based on the downmix signal, an (N−1)-channel decorrelated signal (Z); a dry upmix section maps the downmix signal linearly in accordance with dry upmix coefficients (C) determined based on the dry upmix parameters; a wet upmix section populates an intermediate matrix based on the wet upmix parameters and knowing that the intermediate matrix belongs to a predefined matrix class, obtains wet upmix coefficients (P) by multiplying the intermediate matrix by a predefined matrix, and maps the decorrelated signal linearly in accordance with the wet upmix coefficients; and a combining section combines outputs from the upmix sections to obtain a reconstructed signal ({circumflex over (X)}) corresponding to the signal to be reconstructed.

In cases of rendering a multichannel signal such as a 22.2 channel signal as a 5.1 channel signal, a three dimensional (3D) audio signal may be reproduced using a two dimensional (2D) output channel, but rendered audio signals are sensitively affected by a layout of speakers and may cause distortion of a sound image when the layout of arranged speakers is different from a standard layout. The present invention may solve the aforementioned problem of the prior art. The audio signal rendering method for reducing distortion of a sound image even when the layout of the arranged speakers is different from the standard layout, according to one embodiment of the present invention, includes: receiving a multi-channel signal including a plurality of input channels that are to be converted to a plurality of output channels; obtaining deviation information about at least one output channel, from a location of a speaker and a standard location corresponding to each of the plurality of output channels; and modifying a panning gain from a height channel included in the plurality of input channels to the output channel having the deviation information, based on obtained deviation information.

An apparatus including circuitry configured to: obtain two or more audio signals from respective two or more microphones; determine, in one or more frequency band of the two or more audio signals, a first sound source direction parameter and first sound source energy parameter based on processing of the two or more audio signals; determine, in the one or more frequency band of the two or more audio signals, a second sound source direction parameter and second sound source energy parameter based on processing of the two or more audio signals; obtain a region defining a direction and/or range for a filter; and generate the filter to be applied to the two or more audio signals, wherein filter gain/attenuation parameters are generated based on the region in relation to the first sound source direction parameter, the first sound source energy parameter, the second sound source direction parameter and the second sound source energy parameter.

The following coding scenario is addressed: A number of audio source signals need to be transmitted or stored for the purpose of mixing wave field synthesis, multi-channel surround, or stereo signals after decoding the source signals. The proposed technique offers significant coding gain when jointly coding the source signals, compared to separately coding them, even when no redundancy is present between the source signals. This is possible by considering statistical properties of the source signals, the properties of mixing techniques, and spatial hearing. The sum of the source signals is transmitted plus the statistical properties of the source signals, which mostly determine the perceptually important spatial cues of the final mixed audio channels. Source signals are recovered at the receiver such that their statistical properties approximate the corresponding properties of the original source signals. Subjective evaluations indicate that high audio quality is achieved by the proposed scheme.

The present invention relates to a method and an apparatus for processing a signal, which are used for effectively reproducing a multimedia signal, and more particularly, to a method and an apparatus for processing a signal, which are used for implementing filtering for multimedia signal having a plurality of subbands with a low calculation amount. To this end, provided are a method for processing a multimedia signal including: receiving a multimedia signal having a plurality of subbands; receiving at least one proto-type filter coefficients for filtering each subband signal of the multimedia signal; converting the proto-type filter coefficients into a plurality of subband filter coefficients; truncating each subband filter coefficients based on filter order information obtained by at least partially using characteristic information extracted from the corresponding subband filter coefficients, the length of at least one truncated subband filter coefficients being different from the length of truncated subband filter coefficients of another subband; and filtering the multimedia signal by using the truncated subband filter coefficients corresponding to each subband signal and an apparatus for processing a multimedia signal using the same.