Method and apparatus for representing masked thresholds in a perceptual audio coder
US6778953B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 2, 2000 |
| Grant date | Aug 17, 2004 |
| Priority date | — |
| Expiry date | Jan 24, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10L25/24
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus are disclosed for representing the masked threshold in a perceptual audio coder, using line spectral frequencies (LSF) or another representation for linear prediction (LP) coefficients. The present invention calculates LP coefficients for the masked threshold using known LPC analysis techniques. In one embodiment, the masked thresholds are optionally transformed to a non-linear frequency scale suitable for auditory properties. The LP coefficients are converted to line spectral frequencies or a similar representation in which they can be quantized for transmission. In one implementation, the masked threshold is transmitted only if the masked threshold is significantly different from the previous masked threshold. In between each transmitted masked threshold, the masked threshold is approximated using interpolation schemes. The present invention decides which masked thresholds to transmit based on the change of consecutive masked thresholds, as opposed to the variation of short-term spectra.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.