Speech coding
US6470313B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Mar 4, 1999 |
| Grant date | Oct 22, 2002 |
| Priority date | — |
| Expiry date | Mar 4, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10L19/06
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A variable bit-rate speech coding method determines for each subframe a quantised vector d(i) comprising a variable number of pulses. An excitation vector c(i) for exciting LTP and LPC synthesis filters is derived by filtering the quantised vector d(i), and a gain value gc is determined for scaling the pulse amplitude excitation vector c(i) such that the scaled excitation vector represents the weighted residual signal {tilde over (s)} remaining in the subframe speech signal after removal of redundant information by LPC and LTP analysis. A predicted gain value ĝc is determined from previously processed subframes, and as a function of the energy Ec contained in the excitation vector c(i) when the amplitude of that vector is scaled in dependence upon the number of pulses m in the quantised vector d(i). A quantised gain correction factor {circumflex over (&ggr;)}gc is then determined using the gain value gc and the predicted gain value ĝc.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.