Watermark insertion and extraction into and from a high quality signal is performed using sample rate conversion
US6690812B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 15, 2001 |
| Grant date | Feb 10, 2004 |
| Priority date | — |
| Expiry date | Jan 15, 2022 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2005/91335
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A high-quality signal, for example, a unity-bit coded (DSD) audio signal having a 2.822 MHz bit rate (fs1) is converted to a lower sample rate (fs3) PCM signal by a sample rate converter (102). The watermark is embedded at the lower sample rate by a conventional watermark embedder (101) which is capable of handling signals at this lower rate. The watermark (WM) is not otherwise available. It is subsequently retrieved by subtracting (103) the unwatermarked signal from the watermarked signal, and up-sampled (104) to an intermediate sampling rate (fs2). The DSD signal is converted (110) to a PCM signal at said intermediate sample rate. The retrieved watermark is then added (107) to the PCM signal and the watermarked PCM signal is back-converted (120) to a unity-bit coded DSD signal. The arrangement preferably includes a compensation circuit (105) which compensates the information signal X′ for any (e.g., non-linear) operations performed by the embedder (101) so as to minimize the estimated watermark (WM′). The compensation circuit re-introduces said operations in the DSD domain by controlling parameters, such as, scaling (106, 109) and time shifting (108).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.