EMBEDDING SUPPLEMENTAL DATA IN AN ENCODED SIGNAL.

摘要

METHOD OF EMBEDDING WATERMARKS IN A SIGNAL ENCODED BY AN ENCODER HAVING A FEEDBACK LOOP, FOR EXAMPLE, A SIGMA-DELTA MODULATOR (21,22,23). A DIGITAL WATERMARK PATTERN (W) IS EMBEDDED IN THE SIGNAL (Z) BY MODIFYING SELECTED SAMPLES (FOR EXAMPLE, REPLACING EVERY 100TH BIT) OF THE ENCODED SIGNAL (Y) BY SAMPLES OF THE WATERMARK PATTERN. THE CIRCUIT (24) FOR MODIFYING THE SAMPLES IS LOCATED INSIDE THE LOOP OF THE ENCODER. THE EFFECT OF WATERMARKING IS THUS COMPENSATED IN SUBSEQUENT ENCODING STEPS AND THE SIGNAL-TO-NOISE RATIO IS ONLY SLIGHTLY AFFECTED.