Digital audio companding and error conditioning
US4809274A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Sep 4, 1987 |
| Grant date | Feb 28, 1989 |
| Priority date | — |
| Expiry date | Sep 4, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M7/3053
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A system for companding digital audio signal samples processes the digital audio signal samples to correct errors induced by the compression and expansion processes. These errors are calculated prior to compressing the samples. Such errors are calculated in accordance with a predetermined compression process and a predetermined expansion process; and the digital audio signal samples are corrected in accordance with such calculations prior to compression. The compression process includes providing a 3-bit gain word for a block of 70 samples. The gain word is computed in accordance with the position of the most significant "1" bit in the sample(s) having the peak magnitude. Each individual sample is processed in accordance with the block gain word to compress the sample by reducing the number of magnitude bits. The error calculation process includes calculating an error signal by subtracting a calculated reproduced digital audio signal sample from the digital audio signal sample to be compressed, filtering the error signal by noise-spectral filtering and adding the filtered error signal to the next-providing digital audio signal sample to provide a corrected digital audio signal samp…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.