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Application filed by Квелкомм ИнкорпорейтедfiledCriticalКвелкомм Инкорпорейтед
Publication of UA95858C2publicationCriticalpatent/UA95858C2/en
Compression, Expansion, Code Conversion, And Decoders
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Abstract
A more efficient encoder/decoder is provided in which an N-point MDCT transform is mapped into smaller sized N/2 -point DCT-IV and/or DCT-Π transforms with isolated pre-multiplications which can be moved to a prior or subsequent windowing stage. That is, the windowing operations may be merged with first/last stage multiplications in the core MDCT/IMDCT functions, respectively, thus reducing the total number of multiplications. Additionally, the MDCT may be systematically decimated by factor of 2 by utilizing a uniformly scaled 5-point DCT-Π core function as opposed to the DCT-IV or FFT cores used in many existing MDCT designs in audio codecs. The modified windowing stage merges factors from a transform stage and windowing stage to obtain piece-wise symmetric windowing factors, which can be represented by a sub-set of the piece-wise symmetric windowing factors to save storage space. Such features offer appreciable reduction in complexity and less memory usage than the prior art.
UAA201004619A2007-09-192008-09-19Designing method for filter bank for mdct/imdct in applying for language and audio signal coding
UA95858C2
(en)