INSERTION OF ADDITIONAL DATA IN CODED SIGNAL Russian patent published in 2003 - IPC

FIELD: method for additional data insertion in and extraction from coded signal. SUBSTANCE: method for inserting additional data in coded audio or video signal for changing coded-signal bits without noticeable impact on quality of signal perception involves insertion of watermarks in signal coded by means of decoder incorporating feedback circuit such as sigma- delta modulator. Digital specimen of watermarks is inserted in signal by way of modifying chosen samples (for instance replacing each 100th bit) of coded signal by those of watermark specimen. Circuit designed for modifying these samples is incorporated in coder circuit, In this way result of labeling with watermarks is compensated for in subsequent coding stages and impact on signal-to-noise ratio is negligible. EFFECT: enhanced number of coded-signal bits that can be changed without greatly influencing perception quality. 30 cl, 13 dwg