MDCT domain post-filtering apparatus and method for quality enhancement of speech
US8315853B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 5, 2008 |
| Grant date | Nov 20, 2012 |
| Priority date | — |
| Expiry date | Sep 21, 2031 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10L19/0212
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A post-filtering apparatus and method for speech enhancement in a modified discrete cosine transform (MDCT) domain are disclosed. In the apparatus and method, previous and current MDCT coefficients are used for obtaining a speech spectrum coefficient similar to a real speech spectrum, and a convex function is used for transforming the speech spectrum coefficient and obtaining a post-filter coefficient so that difference can increase in the case where the speech spectrum coefficient is small but decrease in the case where the coefficient is large. Then, the post-filter coefficient is applied to the MDCT coefficient. With this configuration, both the current and previous MDCT values are used, so that it is possible to obtain a spectrum coefficient similar to the real speech spectrum and to obtain a more accurate filter coefficient. Further, the coefficient is adaptively transformed through the convex function, thereby enhancing speech quality.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.