Methods and apparatus for reconstructing non-quantized adaptively transformed voice signals
US5042069A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 18, 1989 |
| Grant date | Aug 20, 1991 |
| Priority date | — |
| Expiry date | Apr 18, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10L25/27
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
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 e…
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