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Gain-adaptive vector quantization for medium-rate speech codingA class of adaptive vector quantizers (VQs) that can dynamically adjust the 'gain' of codevectors according to the input signal level is introduced. The encoder uses a gain estimator to determine a suitable normalization of each input vector prior to VQ coding. The normalized vectors have reduced dynamic range and can then be more efficiently coded. At the receiver, the VQ decoder output is multiplied by the estimated gain. Both forward and backward adaptation are considered and several different gain estimators are compared and evaluated. An approach to optimizing the design of gain estimators is introduced. Some of the more obvious techniques for achieving gain adaptation are substantially less effective than the use of optimized gain estimators. A novel design technique that is needed to generate the appropriate gain-normalized codebook for the vector quantizer is introduced. Experimental results show that a significant gain in segmental SNR can be obtained over nonadaptive VQ with a negligible increase in complexity.
Document ID
19860052841
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Chen, J.-H.
(California Univ. Santa Barbara, CA, United States)
Gersho, A.
(California, University Santa Barbara, United States)
Date Acquired
August 12, 2013
Publication Date
January 1, 1985
Subject Category
Communications And Radar
Accession Number
86A37579
Funding Number(s)
CONTRACT_GRANT: JPL-957063
Distribution Limits
Public
Copyright
Other

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