Fast Complex Quadrature Mirror Filterbanks for MPEG-4 HE-AAC
Spectral Band Replication (SBR) has been introduced in MPEG-4 HE-AAC as bandwidth extension tool. All the framework of SBR is on complex-value domain to avoid the aliasing effect, and hence results in considerable time complexity. This paper focuses on the complex Quadrature Mirror Filter (QMF) banks used in HE-AAC encoder and decoder, and proposes the two fast decomposition methods for the time-consuming matrix operations in the filterbanks, that are based on DCT and DFT respectively. Hence, the time complexity can be effectively reduced by the fast algorithms for DCT and FFT.
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