Perceptual audio coding
US6704705B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 4, 1998 |
| Grant date | Mar 9, 2004 |
| Priority date | — |
| Expiry date | Sep 4, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10L2019/0013
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for perceptual audio coding. The method and apparatus provide high-quality sound for coding rates down to and below 1 bit/sample for a wide variety of input signals including speech, music and background noise. The invention provides a new distortion measure for coding the input speech and training the codebooks, where the distortion measure is based on a masking spectrum of the input frequency spectrum. The invention also provides a method for direct calculation of masking thresholds from a modified discrete cosine transform of the input signal. The invention also provides a predictive and non-predictive vector quantizer for determining the energy of the coefficients representing the frequency spectrum. As well, the invention provides a split vector quantizer for quantizing the fine structure of coefficients representing the frequency spectrum. Bit allocation for the split vector quantizer is based on the masking threshold. The split vector quantizer also makes use of embedded codebooks. Furthermore, the invention makes use of a new transient detection method for selection of input windows.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.