06285774 is referenced by 200 patents and cites 35 patents.

To enable the source of an unauthorized copy of an information-bearing medium, such as a video DVD, to be traced, a compressed digital signal stream to be stored on the medium is altered to include “running marks,” that comprise pixel blocks changing in position frame by frame and encoded with information designating where and when the copy was made. The medium under test is played back synchronously with a reference medium containing the locations of the running marks together with original video. The source of copying message is advantageously encrypted and scrambled to avoid detection or alteration by a copyist. The message preferably is spread, for example into a spread spectrum carrier, to enhance discrimination among a large number of sources and enable demodulation in the presence of noise.

Title
System and methodology for tracing to a source of unauthorized copying of prerecorded proprietary material, such as movies
Application Number
9/92898
Publication Number
6285774 (B1)
Application Date
June 8, 1998
Publication Date
September 4, 2001
Inventor
Jack Ehrhardt
Richmond
VA, US
Michael Bergeron
Glen Allen
VA, US
Shiva Ramadoss
Sterling
VA, US
Guillaume Mercier
Sterling
VA, US
Kobad Bugwadia
Sterling
VA, US
Siu Leong Iu
Falls Church
VA, US
Robert W Schumann
Oakton
VA, US
Agent
McDermott Will & Emery
US
Assignee
Digital Video Express
VA, US
IPC
H04K 1/00
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