Apparatus for decoding a DPCM encoded signal
US5555546A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 8, 1995 |
| Grant date | Sep 10, 1996 |
| Priority date | — |
| Expiry date | Jun 8, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10L2025/783
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A voice decoding apparatus of an adaptive PCM coding system in which an auxiliary controller is provided between a controller and a prediction coefficient holder. The controller receives a voice activity detection flag b separated from a received demodulated signal a and, at the time of transition from the voice-active duration to the voice-nonactive duration and vice versa, outputs a reset signal d and a signal e indicating whether the voice activity detection flag is voice-active or voice-nonactive. The prediction coefficient holder extracts, from an ADPCM decoder for decoding a coded signal c, a prediction coefficient g, calculates and stores its average value for each frame and updates the old value with the new one and, at the time of transition from the voice-nonactive duration to the voice-active duration, outputs an immediately stored value h. Even when the input flag e changes from the voice-nonactive duration to the voice-active duration, the auxiliary controller keeps outputting a flag f indicative of the voice-nonactive duration for about five frame periods, thereby preventing degradation of the tone quality of the pseudo-background noise which is generated and decoded …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.