FIELD: methods for embedding watermarks (spatial pseudonoise sequence) into informational signal (compressed video stream).
SUBSTANCE: watermark is embedded by selective dropping of the least quantized coefficients of discrete-cosine transformation (DCT). The dropped coefficients are sequentially joined in series of remaining coefficients. The decision whether to drop current coefficient or not is made on the basis of preliminary calculated DCT coefficient in watermark buffer and the quantity of already dropped coefficients on the DCT block of 8x8 size.
EFFECT: very simple scheme of bit transfer speed control; lack of necessity for drift compensation.
8 cl, 9 dwg
