Abstract: The invention relates to a system for detecting a watermark using informed detection. A first signal potentially having a watermark embedded is received (601) as is a second signal corresponding to the original signal. The signals are segmented (605) into symbol segments. For each symbol segment a first characteristic is determined (607) for a first section and a second characteristic is determined (609) for a second section in response to the first and second signals in those sections. Specifically, ratios between average envelopes are determined. Thus, the first and second characteristic is indicative of the variations of the envelope during a watermark symbol. A watermark symbol estimate is determined (611) from the first and second characteristic. A sequence of estimated watermark symbols is compared to reference watermark symbols and the presence of a watermark symbol is determined (615) depending on the comparison.

Abstract: There is provided a watermark detector (20) including an input for receiving an input signal (Y?) including watermark content (W) to be searched. A first processor (40) of the detector (20) is operable to analyse portions (100, 110, 120) of the signal (Y?) to identify corresponding sets of characteristic properties or fingerprints (P1 to Pq) and associated temporal descriptors (d1 to dq). A communication link to a database (50) is provided for communicating the fingerprints to the database (50) to identify the signal and to determine corresponding temporal descriptors (MT1 to MTq) corresponding to the portions (100, 110, 120) in the original signal. A second processor (220) is included for calculating from a difference between the temporal descriptors (d1 to dq) and the retrieved temporal descriptors (MT1 to MTq) a scaling factor to which the input signal (Y?) has been subjected. The scaling factor is useable for re-scaling the signal and extracting the watermark from the rescaled signal (Y?).

Abstract: The present invention relates to a method and device for simplifying distribution of a processed media signal and a method and device for distributing a media signal. A properties determining unit (12, 14) determines a set of signal dependent properties (w,a) of a media signal (x). An embedding unit (16) embeds the signal dependent properties in the media signal in order to provide a modified media signal (x?). An extracting unit (22) retrieves the modified media signal (x?) from a media signal storage (18) and extracts the signal dependent properties (w, a). A signal processing unit (24, 26) then processes the media signal using the signal dependent properties, such that the processed media signal can be provided for distribution to at least one recipient. In this way storage space is saved and the complexity of an electronic content delivery system is reduced.

Abstract: A method of dynamically allocating payload bits in a watermarking system (10) is provided. The method including steps of: (a) determining one or more parameters to be conveyed in bits of a payload to be included in watermark information for embedding in programme content; (b) dynamically allocating the bits to corresponding of the one or more parameters so as to represent the one or more parameters in the payload; (c) including the payload in the watermark information; and (d) embedding the watermark information including the payload into the programme content. Such dynamic allocation of payload bits is capable of providing more effective use of payload capacity.

Abstract: The invention relates to a system for embedding a watermark into an input media signal. A plurality of sub-band signals of a sub-band encoded input signal is obtained; preferably by de-multiplexing of the corresponding bitstream. A set of sub-band signals is filtered by a sub-band filter (507) which has a response associated with the watermark. The sub-band filter (507) thereby generates a set of filtered sub-band signals which are combined into an output signal having the desired watermark. The output signal is preferably a compressed sub-band bitstream signal. A low complexity approach for embedding a watermark into a media signal by filtering in the sub-band domain is thus achieved obviating the requirement for decoding and re-encoding of the media signal.

Abstract: The present invention relates to methods, devices, a media signal and a recorded medium for watermarks embedded in the sub-band domain of compressed media. Watermarks (w[n]) are embedded into the sub-band signals (xi?1[n], xi[n], xi+1[n]) of at least one selected sub-band of a compressed bit-stream (bk) using a watermark inserting unit (18). In this way there is no need to fully decode and re-encode the media signal for embedding the watermark. The watermark is embedded in selected sub-bands (e.g. sub-bands 7-15 of 32). In a preferred embodiment, the selected sub-bands are upsampled before embedding and downsampled therafter to avoid aliasing. The invention also allows embedding multiple watermarks in different sub-bands (e.g. one watermark in sub-bands 7-11, and a different watermark in sub-bands 12-16).

Abstract: The invention concerns a method and apparatus for embedding and detecting watermarks in a digital host signal. In the embedding method a watermark sequence of length Lw/N bits carrying predetermined information is generated and then up-sampled by a factor N (preferably N=2). At intermediate sampling points of the up-sampled sequence a modified version of the watermark sequence (in preferred arrangements the negative thereof) is inserted to form a compound watermark sequence of length Lw. The compound watermark sequence is then combined with the host signal to watermark the host signal. The invention finds particular advantage in that the need for a spectral whitening stage in the detector is done away with.

Abstract: The invention concerns a method of bit stream watermarking in a tandem coding system (300). The method involves arranging for the system (300) to comprise a series of stages including a first quantizing unit for processing an input signal to generate a first intermediate signal, a combining unit for embedding a watermarking signal into the intermediate signal to generate a second intermediate signal, and a second quantizing unit for processing the second intermediate signal to generate a watermarked output signal. The first quantizing unit to arranged to include a unit for predicting distortions arising in subsequent stages of the system (300) and generating one or more corresponding quantization noise reduction parameters. Moreover, the system (300) is operable to apply the one or more reduction parameters in at least one of the subsequent stages for reducing noise and/or distortion arising within the system (300).

Abstract: There is provided a method of allocating optimal payload space in a watermarking system. The method includes steps of: (a) obtaining identification parameters relating to programme data content (PC), said identification parameters including at least one or more user identifiers (UID) and one or 5 more programme content identifiers (CID); (b) storing said identification parameters (UID, CID) in one or more databases (30); (c) generating one or more transaction numbers (nTR) capable of being uniquely mapped to corresponding identification parameters (UID, CID) stored in the one or more 10 databases (30); and (d) generating watermark information for carrying said one or more transaction numbers (nTR) and embedding said watermark information as an optimized payload (OPL) into said programme data content (PC) to generate corresponding watermarked data content (WPC).

Abstract: The invention relates to watermarking systems, which irregularly change the embedded watermark so as to avoid hacking the system by averaging-attacks. In averaging attacks, segments of the watermarked signal are accumulated. This causes the host signal to be cancelled out whereas the embedded watermark accumulates coherently. A watermark A thus determined is then subtracted by a hacker from the watermarked signal. This invention exploits the insight that the hacker does not know when the embedded watermark changes (from A to B, or from A to none). Accordingly, fragments of the hacked signal will contain the negative watermark—A being unintentionally embedded by the hacker. This causes the watermark detector to produce a correlation peak of opposite polarity. The invention resides in the detection of such a negative peak, and concluding therefrom that the signal has been tampered. The payload of the watermark is preserved. This provides the possibility to trace back the hacker.

Abstract: The present invention relates to a methods, devices, a media signal as well as an information storage medium related to embedding additional data in a media signal. A first adding unit (12) mixes the media signal (x) with a noise signal (n) in order to provide a modified media signal (x+n), and a combiner unit (14) combines additional data (w) with the modified media signal (x+n) through multiplying the modified media signal with the additional data in order to provide a host modifying media signal (mw). In this way the additional data can be detected with a higher certainty in an output signal (y) if the media signal (x) includes few frequency components.

Abstract: A method of processing an information signal comprising: applying a signal modification process to an information signal resulting in a processed signal, said signal modification process being controlled by at least one control parameter; comparing the processed signal with the information signal to determine a measure of perceptual quality of the processed signal; and adjusting said at least one control parameter in response to the determined measure of perceptual quality. The method is advantageously used in watermarking and compression systems, that use a model of the Human Auditory or Visual System to control the watermark embedding depth or the compression ratio, and that often fail to maintain a constant signal quality because they ignore other artifacts than the mask-to-noise ratio.

Abstract: Methods and apparatus for embedding a watermark in a multimedia signal and detecting the watermark, are described. The method comprises the steps of generating a watermark signal comprising a first sequence of values and a second sequence of values; obtaining a first signal portion corresponding to a first channel and a second signal portion corresponding to a second channel from the multimedia signal, said channels being significantly independent; generating a first host modifying signal as a mixture of the first signal portion and the first sequence; generating a second host modifying signal as a mixture of the second signal portion and the second sequence; and generating a watermarked multimedia signal by combining scaled versions of the host modifying signals with the multimedia signal.

Abstract: Methods and apparatus for processing a multimedia signal comprising a watermark signal are described. The method includes the steps of: removing at least a portion of the watermark signal, and adding a new watermark signal to the multimedia signal so as to form a new watermarked multimedia signal.

Abstract: Method and apparatus are described for compensating for a linear time scale change in a received signal, so as to correctly rescale the frame sequence of the received signal. Firstly, an initial estimate of the sequence of symbols is extracted from the received signal. Successive estimates of correctly time scaled sequences of the symbols are then generated by interpolating the values of the initial estimates.

Abstract: Method and apparatus are described for compensating for time offset in a received signal, so as to correctly align the frame sequence of a received signal to a sequence of transmitted symbols. Each symbol extends over Ts signal samples. The received signal is first divided into a sequence of frames of length Ts, and then each framedivided into a multiplicity of Nb sub-frames. Subsequently, Nb sequences of values are formed, where every successive value in each sequence is derived from the corresponding sub-frame within each successive frame. Each of the Nb sequences is an estimate for the correctly aligned sequence of transmitted symbols.

Abstract: A method of generating a watermark signal, embedding the watermark signal within a multimedia signal, and subsequently detecting the watermark signal is described. The watermark signal is the sum of two sequences of values, the second sequence of values being a circularly shifted version of the first sequence.

Abstract: A window shaping function is described which has an integral over the window shaping function of zero. Compared with conventional window shaping functions, this window shaping function improves the robustness of the watermark signal for a given quality of host signal. Methods and apparatus suitable for utilizing this window shaping function within a watermarking scheme are described.