Stealthy audio watermarking
US7020285B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 12, 2000 |
| Grant date | Mar 28, 2006 |
| Priority date | — |
| Expiry date | Aug 10, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2005/91335
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Described herein is technology for inserting and detecting watermarks in signals, such as a music clip. In one described implementation, a watermarking system employs chess spread-spectrum sequences (i.e., “chess watermarks”) to improve the balance of positive and negative chips in the watermarking sequences. In another described implementation, a watermarking system employs an energy-level trigger to determine whether to skip encoding of a portion of a watermark within a given time span of a clip. If a large discrepancy in energy levels exists over a given time frame, then the frame is not watermarked, to avoid audible time-dispersion of artifacts due to spectral modifications. In another described implementation, a watermarking system begins encoding of a watermark at a variable position after the beginning of a clip.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.