TIME-VARYING TIME-FREQUENCY TILINGS USING NON-UNIFORM ORTHOGONAL FILTERBANKS BASED ON MDCT ANALYSIS/SYNTHESIS AND TDAR

摘要

Embodiments provide a method for processing an audio signal to obtain a subband representation of the audio signal. The method comprises a step of performing a cascaded lapped critically sampled transform on at least two partially overlapping blocks of samples of the audio signal, to obtain sets of subband samples on the basis of a first block of samples of the audio signal, and to obtain sets of subband samples on the basis of a second block of samples of the audio signal. Further, the method comprises a step of identifying, in case that the sets of subband samples that are based on the first block of samples represent different regions in a time-frequency plane compared to the sets of subband samples that are based on the second block of samples, one or more sets of subband samples out of the sets of subband samples that are based on the first block of samples and one or more sets of subband samples out of the sets of subband samples that are based on the second block of samples that in combination represent the same region of the time-frequency plane. Further, the method comprises a step of performing time-frequency transforms on the identified one or more sets of subband samples out of the sets of subband samples that are based on the first block of samples and/or the identified one or more sets of subband samples out of the sets of subband samples that are based on the second block of samples, to obtain one or more time-frequency transformed subband samples, each of which represents the same region in the time-frequency plane than a corresponding one of the identified one or more subband samples or one or more time-frequency transformed versions thereof. Further, the method comprises a step of performing a weighted combination of two corresponding sets of subband samples or time-frequency transformed versions thereof, one obtained on the basis of the first block of samples of the audio signal and one obtained on the basis of the second block of samples of the audio signal, to obtain aliasing reduced subband representations of the audio signal.