US 12,260,867 B2
Time-varying time-frequency tilings using non-uniform orthogonal filterbanks based on MDCT analysis/synthesis and TDAR
Nils Werner, Erlangen (DE); and Bernd Edler, Erlangen (DE)
Assigned to Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., Munich (DE)
Filed by Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., Munich (DE)
Filed on Feb. 14, 2022, as Appl. No. 17/671,123.
Application 17/671,123 is a continuation of application No. PCT/EP2020/073742, filed on Aug. 25, 2020.
Claims priority of application No. 19194145 (EP), filed on Aug. 28, 2019.
Prior Publication US 2022/0165283 A1, May 26, 2022
Int. Cl. G10L 19/02 (2013.01); G10L 21/038 (2013.01)
CPC G10L 19/0204 (2013.01) [G10L 19/0212 (2013.01); G10L 21/038 (2013.01)] 18 Claims
OG exemplary drawing
 
1. An audio processor for processing an audio signal to acquire a subband representation of the audio signal, the audio processor comprising:
a cascaded lapped critically sampled transform stage configured to perform a cascaded lapped critically sampled transform on at least two partially overlapping blocks of samples of the audio signal, to acquire sets of subband samples on the basis of a first block of samples of the audio signal, and to acquire sets of subband samples on the basis of a second block of samples of the audio signal;
a first time-frequency transform stage configured to identify, in case that sets of subband samples that are based on the first block of samples represent different regions in a time-frequency plane compared to sets of subband samples that are based on the second block of samples, one or more first identified sets of subband samples out of the sets of subband samples that are based on the first block of samples and one or more second identified 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 in the time-frequency plane, and to time-frequency transform the identified one or more first 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 second sets of subband samples out of the sets of subband samples that are based on the second block of samples, to acquire one or more time-frequency transformed subband samples, each of which represents the same region in the time-frequency plane as a corresponding one of the one or more first or second identified sets of subband samples or one or more time-frequency transformed versions of the one or more first or second identified sets of subband samples; and
a time domain aliasing reduction stage configured to perform a weighted combination of two corresponding sets of subband samples or time-frequency transformed versions of the two corresponding sets of subband samples, one acquired on the basis of the first block of samples of the audio signal and one acquired on the basis of the second block of samples of the audio signal, to acquire aliasing reduced subband representations of the audio signal.