Temporal synchronization of video watermark decoding
US6785401B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 9, 2001 |
| Grant date | Aug 31, 2004 |
| Priority date | — |
| Expiry date | Oct 17, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T1/0028
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method of synchronizing a watermark decoder with a watermark encoder uses a spatio-temporal (3D) synchronization pattern added to a data pattern to produce a watermark pattern for embedment into a signal. The spatio-temporal synchronization pattern is formed by multiplying a spatial (2D) synchronization pattern with a pseudo-noise sequence for a block of signal frames having a duration of N frames. Quadrature carrier modulation may be used to increase detectability of the watermark pattern at the watermark decoder. The watermarked signal is correlated with the spatial synchronization pattern to recover a temporal synchronization signal that is used to determine a temporal offset between the watermark encoder and watermark decoder. The temporal offset is then used to synchronize the watermark decoder with the watermark encoder. Once synchronized various applications may be implemented using the spatial synchronization pattern, and error correction may be applied to the data pattern as well as the addition of a low data rate channel using Walsh codes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.