Abstract: A method and apparatus (200) for embedding a watermark in an information signal bit-stream are described. The method comprises receiving a portion of an information signal bit-stream (MPEG2). A first copy of the received portion is stored in a first buffer (220). A second copy of the received portion is watermarked, and the resulting watermarked signal stored in a second buffer (240). At predetermined intervals, a check is performed to determine if the bit-rate of the received portion has been changed by being watermarked. If the check determines the bit-rate has changed, the first copy of the received portion from the first buffer is output. Otherwise the watermarked signal from the second buffer is output.

Abstract: Method of and system for detecting a watermark in MPEG-2 encoded video data during high-speed copying of the video data. A bus spy (120) selects independently coded frames, such as I-frames, from the video data and feeds the selected frames to a watermark detector (130) for detecting a watermark therein. By only supplying some of the frames to the watermark detector (130), the average input data rate for the watermark detector (130) is much lower than the data rate during the high-speed copying. Various embodiments present various ways to efficiently supply the contents of the selected frames to the watermark detector (130).

Abstract: A method and arrangement are disclosed for processing a compressed media signal, for example, embedding a watermark in an MPEG2 video signal. The watermark, a spatial noise pattern (140), is embedded (123) by selectively discarding the smallest quantized DCT coefficients. The discarded coefficients are subsequently merged in the runs of other run/level pairs. To compensate for a too large reduction of the bit rate, some of the new run/level pairs are not variable-length encoded (124) but represented by longer code words according to further coding rule (125) providing such longer code words, for example, MPEG's “Escape coding”.

Abstract: Method of and system for detecting a watermark in MPEG-2 encoded video data during high-speed copying of the video data. A bus spy (120) selects independently coded frames, such as I-frames, from the video data and feeds the selected frames to a watermark detector (130) for detecting a watermark therein. By only supplying some of the frames to the watermark detector (130), the average input data rate for the watermark detector (130) is much lower than the data rate during the high-speed copying. Various embodiments present various ways to efficiently supply the contents of the selected frames to the watermark detector (130).