Methods and devices for encoding and / or decoding diving audio signals

Claims

1. A method for determining a reconstructed multi-channel signal from encoded audio data indicating a plurality of reconstructed channel signals and from encoded metadata indicating joint coding metadata, wherein the method comprises the steps of: decoding the encoded audio data to provide a plurality of reconstructed channel signals, and decoding the encoded metadata to provide joint coding metadata; and determine a reconstructed multi-channel signal from a plurality of reconstructed channel signals using joint coding metadata.

2. The method according to claim 1, wherein the plurality of reconstructed channel signals represents a first-order ambiphonic signal, namely, in B-format or in A-format.

3. The method according to claim 1, wherein the combined encoding metadata comprises: upmix data, namely, an upmix matrix that provides upmixing of a plurality of reconstructed channel signals into a reconstructed multi-channel signal; and / or decorrelation data that provide the ability to generate a reconstructed multichannel signal with a predetermined covariance.

4. The method according to claim 1, wherein the joint coding metadata comprises different metadata for different frequency sub-bands of the reconstructed multi-channel signal.

5. The method of claim 1, wherein decoding the encoded audio data comprises a step of decoding each of the plurality of reconstructed channel signals based on the waveform, in particular using a mono decoder for each reconstructed channel signal.

6. The method of claim 1, wherein the encoded metadata is decoded using an entropy decoder.

7. The method according to paragraph 1, wherein: the reconstructed multi-channel signal comprises one or more reconstructed object signals of one or more audio objects; and the method comprises a step of decoding, in particular using an entropy decoder, object metadata for one or more audio objects from encoded metadata.

8. The method according to paragraph 1, wherein: a plurality of reconstructed channel signals form a sound field representation signal called "SR", namely, a K-order ambiphonic signal, with K≥1; the reconstructed multi-channel signal is determined by up-mixing a plurality of reconstructed channel signals using joint coding metadata; and the reconstructed multichannel signal comprises a reconstructed SR signal, namely an L-order ambiphonic signal, with L≥K, and one or more reconstructed object signals of one or more audio objects.

9. The method according to paragraph 1, in which the joint coding metadata is configured to perform an inversion of the energy multiplexing operation on the plurality of recovered channel signals; and / or the joint coding metadata is configured to perform a reverse prediction operation for at least some of the plurality of reconstructed channel signals; and / or the joint coding metadata is configured to perform the inversion of the Karhunen-Loeve transform, the transform based on principal component analysis, and / or the transform based on singular value decomposition for at least some of the plurality of reconstructed channel signals 10. The method according to paragraph 1, in which method (contains a step in which it is determined that the reconstructed multichannel signal should be determined using the second mode; in the second mode, the joint coding metadata comprises prediction data and / or transform data configured to redistribute energy between different reconstructed channel signals; in the second mode, determining the reconstructed multi-channel signal comprises a step of redistributing energy between different reconstructed channel signals (using predictive data and / or transform data; and in the second mode, the reconstructed multi-channel signal contains a number of channels identical to the number of channels of the set of reconstructed channel signals.

11. The method of claim 10, wherein the transform data specifies an inverse of a Karhunen-Loeve transform, a principal component analysis transform, and / or a singular value decomposition transform that is to be applied to at least some of the plurality of reconstructed channel signals to determine a reconstructed multi-channel signal.

12. The method according to paragraph 10, in which the reconstructed multichannel input signal contains a sequence of frames; and the method comprises a step in which it is determined, for each frame of the sequence of frames, whether or not the second mode should be used.

13. The method according to claim 10, comprising the steps of extracting encoded audio data and encoded metadata from the bitstream; and extract from the bit stream an indicator that indicates whether the second mode should be used or not.

14. The method according to claim 10, comprising a step of preparing a reconstructed multi-channel signal by rendering.

15. A decoding unit for determining a reconstructed multi-channel signal from encoded audio data indicating a plurality of reconstructed channel signals and from encoded metadata indicating joint coding metadata, wherein the decoding unit is configured to: decode encoded audio data to provide multiple reconstructed channel signals; decode the encoded metadata to provide the combined encoding metadata; and determine a reconstructed multi-channel signal from a plurality of reconstructed channel signals using joint coding metadata.