Apparatus, method and computer program for encoding an audio signal or for decoding an encoded audio scene

Method of generating an encoded audio scene from an audio signal comprising a first frame and a second frame, comprising:

• determining a first soundfield parameter representation for the first frame from the audio signal in the first frame and a second soundfield parameter representation for the second frame from the audio signal in the second frame;
• and
• analyzing the audio signal to determine, depending on the audio signal, that the first frame is an active frame and the second frame is an inactive frame,
• wherein determining the first soundfield parameter representation comprises determining, from the second frame of the audio signal, for each sound source, a parametric description for the second frame,
• wherein determining the first soundfield parameter representation comprises decomposing the second frame into frequency bin(s), each frequency bin representing an individual sound source, and determining, for each frequency bin, at least one inactive spatial parameter as the second soundfield parameter representation for the second frame, the at least one inactive spatial parameter comprising a direction parameter, a direction of arrival parameter, a diffuseness parameter, or an energy ratio parameter,
• the method further comprising:
• generating an encoded audio signal, the encoded audio signal providing an encoded audio signal for the first frame being the active frame and the parametric description for the second frame being the inactive frame;
• and
• composing the encoded audio scene by bringing together the first soundfield parameter representation for the first frame, the second soundfield parameter representation for the second frame, the encoded audio signal for the first frame, and the parametric description for the second frame.

A non-transitory digital storage medium having a computer program stored thereon to perform the method of generating an encoded audio scene from an audio signal comprising a first frame and a second frame, comprising:

• determining a first soundfield parameter representation for the first frame from the audio signal in the first frame and a second soundfield parameter representation for the second frame from the audio signal in the second frame;
• and
• analyzing the audio signal to determine, depending on the audio signal, that the first frame is an active frame and the second frame is an inactive frame,
• wherein determining the first soundfield parameter representation comprises determining, from the second frame of the audio signal, for each sound source, a parametric description for the second frame,
• wherein determining the first soundfield parameter representation comprises decomposing the second frame into frequency bin(s), each frequency bin representing an individual sound source, and determining, for each frequency bin, at least one inactive spatial parameter as the second soundfield parameter representation for the second frame, the at least one inactive spatial parameter comprising a direction parameter, a direction of arrival parameter, a diffuseness parameter, or an energy ratio parameter,
• the method further comprising:
• generating an encoded audio signal, the encoded audio signal providing an encoded audio signal for the first frame being the active frame and the parametric description for the second frame being the inactive frame;
• and
• composing the encoded audio scene by bringing together the first soundfield parameter representation for the first frame, the second soundfield parameter representation for the second frame, the encoded audio signal for the first frame, and the parametric description for the second frame,
• when said computer program is run by a computer.