Apparatus and method for processing an input audio signal using cascaded filterbanks

Audio decoder comprising an apparatus for processing a time discrete input audio signal, comprising:

• an analysis filterbank comprising an analysis filterbank and comprising a number of analysis filterbank channels, wherein the analysis filterbank is configured for receiving, at the analysis filterbank input, the time discrete input audio signal and is configured for filtering the time discrete input audio signal to acquire a plurality of first subband signals and to output the plurality of first subband signals;
• and
• a synthesis filterbank comprising a synthesis filterbank input, the synthesis filterbank being configured to receive, at the synthesis filterbank input, a group of first subband signals of the plurality of first subband signals output by the analysis filterbank, and to synthesize and output a time discrete audio intermediate signal using the group of first subband signals, where the group of first subband signals comprises a smaller number of subband signals than the number of analysis filterbank channels of the analysis filterbank,
• wherein the time discrete audio intermediate signal has a bandwidth being smaller than a bandwidth of the time discrete input audio signal, or wherein a sampling rate of the time discrete audio intermediate signal is smaller than a sampling rate of the time discrete input audio signal.

Method of audio decoding for processing a time discrete input audio signal, comprising:

• receiving, by a synthesis filterbank comprising a synthesis filterbank input, at the synthesis filterbank input, a plurality of time discrete first subband signals representing the time discrete input audio signal and having been generated by an analysis filterbank,
• synthesizing, by the synthesis filterbank, an audio intermediate signal from the plurality of time discrete first subband signals representing the time discrete input audio signal, and outputting the audio intermediate signal, wherein a number of channels of the synthesis filterbank is smaller than a number of channels of the analysis filterbank;
• and
• receiving, by a further analysis filterbank comprising a further analysis filterbank input, at the further analysis filterbank input, the audio intermediate signal;
• generating, by the further analysis filterbank, a plurality of time discrete second subband signals from the audio intermediate signal, and outputting the plurality of time discrete second subband signals, wherein the further analysis filterbank comprises a number of channels being different from the number of channels of the synthesis filterbank, and
• wherein a sampling rate of a time discrete subband signal of the plurality of second time discrete subband signals is different from a sampling rate of a time discrete first subband signal of the plurality of time discrete first subband signals.

Method of audio decoding for processing a time discrete input audio signal, comprising:

• receiving, at an analysis filterbank input of an analysis filterbank, the time discrete input audio signal;
• analysis filtering, by the analysis filterbank, the time discrete input audio signal to acquire and output a plurality of first subband signals, wherein the analysis filterbank comprises a number of analysis filterbank channels;
• receiving, at a synthesis filterbank input of a synthesis filterbank, a group of first subband signals of the plurality of first subband signals;
• synthesis filtering, by the synthesis filterbank, the group of first subband signals of the plurality of first subband signals to synthesize a time discrete audio intermediate signal and to output, at the synthesis filterbank output, the time discrete audio intermediate signal, wherein the group of first subband signals comprises a smaller number of subband signals than the number of analysis filterbank channels of the analysis filterbank,
• wherein the time discrete audio intermediate signal has a bandwidth being smaller than a bandwidth of the time discrete input audio signal, or
• wherein a sampling rate of the time discrete audio intermediate signal is smaller than a sampling rate of the time discrete input audio signal.

Non-transitory storage medium having stored thereon a computer program comprising a program code for performing, when running on a computer, a method of audio decoding for processing a time discrete input audio signal, the method comprising:

• receiving, by a synthesis filterbank comprising a synthesis filterbank input, at the synthesis filterbank input, a plurality of time discrete first subband signals representing the time discrete input audio signal and having been generated by an analysis filterbank,
• synthesizing, by the synthesis filterbank, an audio intermediate signal from the plurality of time discrete first subband signals representing the time discrete input audio signal, and outputting the audio intermediate signal, wherein a number of channels of the synthesis filterbank is smaller than a number of channels of the analysis filterbank;
• and
• receiving, by a further analysis filterbank comprising a further analysis filterbank input, at the further analysis filterbank input, the audio intermediate signal;
• generating, by the further analysis filterbank, a plurality of time discrete second subband signals from the audio intermediate signal and outputting the plurality of time discrete second subband signals,
• wherein the further analysis filterbank comprises a number of channels being different from the number of channels of the synthesis filterbank, or
• wherein a sampling rate of a time discrete subband signal of the plurality of second time discrete subband signals is different from a sampling rate of a time discrete first subband signal of the plurality of time discrete first subband signals.

Non-transitory storage medium having stored thereon a computer program comprising a program code for performing, when running on a computer, a method of audio decoding for processing a time discrete input audio signal, the method comprising:

• receiving, at an analysis filterbank input of an analysis filterbank, the time discrete input audio signal;
• analysis filtering, by the analysis filterbank, the time discrete input audio signal to acquire and output a plurality of first subband signals, wherein the analysis filterbank comprises a number of analysis filterbank channels;
• receiving, at a synthesis filterbank input of a synthesis filterbank, a group of first subband signals of the plurality of first subband signals;
• synthesis filtering, by the synthesis filterbank, the group of first subband signals of the plurality of first subband signals to synthesize a time discrete audio intermediate signal, and to output the time discrete audio intermediate signal,
• wherein the group of first subband signals comprises a smaller number of subband signals than the number of analysis filterbank channels of the analysis filterbank,
• wherein the time discrete audio intermediate signal has a bandwidth being smaller than a bandwidth of the time discrete input audio signal, or
• wherein a sampling rate of the time discrete audio intermediate signal is smaller than a sampling rate of the time discrete input audio signal.