Codebook structure for changeable pulse multimode speech coding
US6556966B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Sep 15, 2000 |
| Grant date | Apr 29, 2003 |
| Priority date | — |
| Expiry date | May 12, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10L2019/0011
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A speech compression system with a special fixed codebook structure and a new search routine is proposed for speech coding. The system is capable of encoding a speech signal into a bitstream for subsequent decoding to generate synthesized speech. The codebook structure uses a plurality of subcodebooks. Each subcodebook is designed to fit a specific group of speech signals. A criterion value is calculated for each subcodebook to minimize an error signal in a minimization loop as part of the coding system. An external signal sets a maximum bitstream rate for delivering encoded speech into a communications system. The speech compression system comprises a full-rate codec, a half-rate codec, a quarter-rate codec and an eighth-rate codec. Each codec is selectively activated to encode and decode the speech signals at different bit rates to enhance overall quality of the synthesized speech at a limited average bit rate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.