Pacific Communications Sciences, Inc.

Pacific Communication Science, Inc.

Harprit Chhatwal

Philip J Wilson

Apparatus and method for reconstructing non-quantized adaptively transformed voice signals are shown to include noise shaping wherein the spectral envelope is scaled prior to generating bit allocation and energy substitution which is achieved after dequantization by generating the spectral envelope information for each block of transform coefficients based upon side information, generating transform coefficients which correspond to transform coefficients which were not de-quantized and for substituting the generated transform coefficients into said blocks; and transforming said blocks of de-quantized transform coefficients and generated transform coefficients from said transform domain into said time domain. Generating transform coefficients is accomplished by determining from the bit allocation signal to which of the transform coefficients no bits were allocated, retrieving the spectral envelope information corresponding to the transform coefficients to which no bits were allocated, providing a positive or negative sign to each item of spectral envelope information so retrieved, scaling the magnitude of each item of spectral envelope information so retrieved, and by substituting each item of spectral envelope information so retrieved into the block of de-quantized transform coefficients after each item has been given a sign and scaled.

Methods and apparatus for reconstructing non-quantized adaptively

A method and apparatus for removing the periodicity from a speech signal in a transform coder prior to the quantization of the speech signal, which speech signal is a sampled time domain speech signal composed of information samples, the transform coder sequenctially segregating the speech signal into blocks of information samples, is shown to include apparatus and method for determining the pitch in each of the sample blocks, determininig a long term predetermined parameter (LTP) for each of the blocks based on the pitch determined for each block, calculating a periodicity value for each sample in the block wherein the calculation of the periodicity value is based upon the pitch and the long term predictor parameter, generating a revised block of difference samples by subtracting the periodically value from the corresponding sample, and performing adaptive transform coding on each of the difference blocks.

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Harprit Chhatwal