New patents are issued by the USPTO on Tuesdays. Both of today's Sportlight Patents concern aspects of digital watermarking. Assigned to RPX, the first patent addresses techniques using watermarking for advertisement detection. Assigned to Thomson (FR), the second patent addresses techniques for detecting which one of symbols of watermark data is embedded in a received signal.
9,147,112, "Advertisement detection," assigned to RPX Corporation
A method and system for detection of video segments in compressed digital video streams is presented. The compressed digital video stream is examine to determine synchronization points, and the compressed video signal is analyzed following detection of the synchronization points to create video fingerprints that are subsequently compared against a library of stored fingerprints.
9,147,402, "Method and apparatus for detecting which one of symbols of watermark data is embedded in a received signal," assigned to Thomson Licensing (FR).
Watermark symbol detection requires a detection metric for deciding at decoder side which candidate symbol is embedded inside the audio or video signal content. The invention provides an improved detection metric processing that achieves a reliable detection of watermarks in the presence of additional noise and echoes, and that is adaptive to signal reception conditions and requires a decreased computational power. This is performed by taking into account the information contained in the echoes of the received audio signal in the decision metric and comparing it with the corresponding metric obtained from decoding a non-marked audio signal, based on recursive calculation of false positive detection rates of peaks in correlation result values. The watermark symbol corresponding to the reference sequence having the lowest false positive error is selected as the embedded one.