Audio decoder, audio encoder, method for providing at least four audio channel signals on the basis of an encoded representation, method for providing an encoded representation on the basis of at least four audio channel signals and computer program using a bandwidth extension

An audio encoder for providing an encoded representation on the basis of at least four audio channel signals, comprising:

• a first bandwidth extension parameter extraction configured to acquire a first set of common bandwidth extension parameters on the basis of a first audio channel signal and a third audio channel signal;
• a second bandwidth extension parameter extraction configured to acquire a second set of common bandwidth extension parameters on the basis of a second audio channel signal and a fourth audio channel signal;
• a first multi-channel encoding configured to jointly encode at least the first audio channel signal and the second audio channel signal using a multi-channel encoding, to acquire a first downmix signal;
• a second multi-channel encoding is configured to jointly encode at least the third audio channel signal and the fourth audio channel signal using a multi-channel encoding, to acquire a second downmix signal;
• and
• wherein the audio encoder is configured to jointly encode the first downmix signal and the second downmix signal using a multi-channel encoding, to acquire an encoded representation of the first downmix signal and the second downmix signal.

A method for providing at least four audio channel signals on the basis of an encoded representation, wherein the method comprises:

• providing a first downmix signal and a second downmix signal on the basis of a jointly encoded representation of the first downmix signal and the second downmix signal using a multi-channel decoding;
• providing at least a first audio channel signal and a second audio channel signal on the basis of the first downmix signal using a multi-channel decoding;
• providing at least a third audio channel signal and a fourth audio channel signal on the basis of the second downmix signal using a multi-channel decoding;
• performing a multi-channel bandwidth extension on the basis of the first audio channel signal and the third audio channel signal, to acquire a first bandwidth-extended channel signal and a third bandwidth-extended channel signal;
• and
• performing a multi-channel bandwidth extension on the basis of the second audio channel signal and the fourth audio channel signal, to acquire the second bandwidth extended channel signal and the fourth bandwidth extended channel signal.

A method for providing an encoded representation on the basis of at least four audio channel signals, the method comprising:

• acquiring a first set of common bandwidth extension parameters on the basis of a first audio channel signal and a third audio channel signal;
• acquiring a second set of common bandwidth extension parameters on the basis of a second audio channel signal and a fourth audio channel signal;
• jointly encoding at least the first audio channel signal and the second audio channel signal using a multi-channel encoding, to acquire a first downmix signal;
• jointly encoding at least the third audio channel signal and the fourth audio channel signal using a multi-channel encoding, to acquire a second downmix signal;
• and
• jointly encoding the first downmix signal and the second downmix signal using a multi-channel encoding, to acquire an encoded representation of the first downmix signal and the second downmix signal.

A non-transitory digital storage medium having a computer program stored thereon to perform the method for providing at least four audio channel signals on the basis of an encoded representation, wherein the method comprises:

• providing a first downmix signal and a second downmix signal on the basis of a jointly encoded representation of the first downmix signal and the second downmix signal using a multi-channel decoding;
• providing at least a first audio channel signal and a second audio channel signal on the basis of the first downmix signal using a multi-channel decoding;
• providing at least a third audio channel signal and a fourth audio channel signal on the basis of the second downmix signal using a multi-channel decoding;
• performing a multi-channel bandwidth extension on the basis of the first audio channel signal and the third audio channel signal, to acquire a first bandwidth-extended channel signal and a third bandwidth-extended channel signal;
• and
• performing a multi-channel bandwidth extension on the basis of the second audio channel signal and the fourth audio channel signal, to acquire the second bandwidth extended channel signal and the fourth bandwidth extended channel signal,
• when said computer program is run by a computer.

A non-transitory digital storage medium having a computer program stored thereon to perform the method for providing an encoded representation on the basis of at least four audio channel signals, the method comprising:

• acquiring a first set of common bandwidth extension parameters on the basis of a first audio channel signal and a third audio channel signal;
• acquiring a second set of common bandwidth extension parameters on the basis of a second audio channel signal and a fourth audio channel signal;
• jointly encoding at least the first audio channel signal and the second audio channel signal using a multi-channel encoding, to acquire a first downmix signal;
• jointly encoding at least the third audio channel signal and the fourth audio channel signal using a multi-channel encoding, to acquire a second downmix signal;
• and
• jointly encoding the first downmix signal and the second downmix signal using a multi-channel encoding, to acquire an encoded representation of the first downmix signal and the second downmix signal,
• when said computer program is run by a computer.