Abstract: A method for encoding an input audio stream including the steps of obtaining a first playback stream presentation of the input audio stream intended for reproduction on a first audio reproduction system, obtaining a second playback stream presentation of the input audio stream intended for reproduction on a second audio reproduction system, determining a set of transform parameters suitable for transforming an intermediate playback stream presentation to an approximation of the second playback stream presentation, wherein the transform parameters are determined by minimization of a measure of a difference between the approximation of the second playback stream presentation and the second playback stream presentation, and encoding the first playback stream presentation and the set of transform parameters for transmission to a decoder.

Abstract: A gain contribution of the audio signal for each of the N audio objects to at least one of M speakers may be determined. Determining the gain contribution may involve determining a center of loudness position that is a function of speaker (or cluster) positions and gains assigned to each speaker (or cluster). Determining the gain contribution also may involve determining a minimum value of a cost function. A first term of the cost function may represent a difference between the center of loudness position and an audio object position.

Abstract: A gain contribution of the audio signal for each of the N audio objects to at least one of M speakers may be determined. Determining the gain contribution may involve determining a center of loudness position that is a function of speaker (or cluster) positions and gains assigned to each speaker (or cluster). Determining the gain contribution also may involve determining a minimum value of a cost function. A first term of the cost function may represent a difference between the center of loudness position and an audio object position.

Abstract: A multi-channel audio encoder (10) for encoding a multi-channel audio signal (101), e.g. a 5.1 channel audio signal, into a spatial down-mix (102), e.g. a stereo signal, and associated parameters (104, 105). The encoder (10) comprises first and second units (110, 120). The first unit (110) encodes the multi-channel audio signal (101) into the spatial down-mix (102) and parameters (104). These parameters (104) enable a multi-channel decoder (20) to reconstruct the multi-channel audio signal (203) from the spatial down-mix (102). The second unit (120) generates, from the spatial down-mix (102), parameters (105) that enable the decoder to reconstruct the spatial down-mix (202) from an alternative down-mix (103), e.g. a so-called artistic down-mix that has been manually mixed in a sound studio. In this way, the decoder (20) can efficiently deal with a situation in which an alternative down-mix (103) is received instead of the regular spatial, down-mix (102).