The present invention relates generally to digital watermarking and other forms of content identification. One claim recites a method including: receiving audio or video content, the audio or video content comprising at least two digital watermark payload layers, a first watermark payload layer comprising...http://www.google.com/patents/US7587601?utm_source=gb-gplus-sharePatent US7587601 - Digital watermarking methods and apparatus for use with audio and video content
