This disclosure describes several video watermarking and fingerprinting enhancements. These enhancements include synchronizing watermark detectors with one-dimensional calibration signals, layering digital watermarks, watermarks for version control, compressed domain watermarking, watermarking of video...http://www.google.de/patents/US7020304?utm_source=gb-gplus-sharePatent US7020304 - Digital watermarking and fingerprinting including synchronization, layering, version control, and compressed embedding
