Abstract: For some video processing applications, most notably watermark detection (40), it is necessary to add or average (parts of) the two interlaced fields which make up a frame. This operation is not trivial in the MPEG domain due to the existence of frame-encoded DCT blocks. The invention provides a method and arrangement for adding the fields without requiring a frame memory or an on-the-fly inverse DCT. To this end, the mathematically required operations of inverse vertical DCT (321) and addition (322) are combined with a basis transform (323). The basis transform is chosen to be such that the combined operation is physically replaced by multiplication with a sparse matrix (32). Said sparse matrix multiplication can easily be executed on-the-fly. The inverse basis transform (35) is postponed until after the desired addition (33, 34) has been completed.

Abstract: Disclosed is a method of embedding a watermark in an information signal (x(n)), such as an audio signal. The method comprises the steps of segmenting the audio signal into overlapping frames (xs(n)) using a set of analysis windows (ha(n)), calculating watermark segments (ws′(n)) for the overlapping frames, reconstructing a watermark signal (w′(n)) from the watermark segments using a set of reconstruction windows (hr(n)) which are complementary to the analysis windows, and adding the watermark signal to the information signal. The analysis and reconstruction windows may be constructed on the basis of prototype windows to fulfil predetermined complementary conditions. The analysis and reconstruction windows may be adapted to the contents of the information signal.

Abstract: This invention relates to a method and an arrangement for embedding auxiliary data in an information signal.

Abstract: Disclosed are methods of embedding and detecting a watermark in an information signal (x(n), y′(n)) which are robust against sampling rate conversions (102) of the watermarked signal (y(n)). The frame lengths used by the embedder (101) and the detector (103), respectively, are adapted so as to preserve a constant ratio between the respective sampling rate and frame length. The frame lengths may be calculated from a greatest common divisor of a set of sampling rates providing watermarks which are robust against sampling rate conversions between any sampling rates of the set of sampling rates.

Abstract: Described is a transmission system for transmitting a multicarrier signal from a transmitter (10) to a receiver (20). The multicarrier signal comprises a plurality of subcarriers. The receiver (20) comprises a channel estimator (28) for estimating amplitudes of the subcarriers and for estimating time derivatives of the amplitudes. The receiver (20) further comprises an equalizer (24) for canceling intercarrier interference included in the received multicarrier signal in dependence on the estimated amplitudes and derivatives (29). The channel estimator (28) and/or the equalizer (24) are arranged for exploiting an amplitude correlation between the amplitudes of different subcarriers and/or for exploiting a derivative correlation between the derivatives of different subcarriers By making use of this correlation the complexity of the receiver (20) can be substantially reduced.

Abstract: Disclosed is a non-frame-based method and an arrangement for embedding a watermark in an information signal (x(n)), e.g. an audio signal. The method comprises calculating (101) a non-cyclic convolution of the information signal with a watermark signal (v(n)) and combining (102) the convolution with the information signal. The non-cyclic convolution may be calculated by overlapped Fast Fourier transform filtering.

Abstract: Hashes are short summaries or signatures of data files which can be used to identify the file. Hashing multimedia content (audio, video, images) is difficult because the hash of original content and processed (e.g. compressed) content may differ significantly.

Abstract: The invention relates to a method of checking the correct operation of a signal transformation wherein a input signal is transformed into an output signal.

Abstract: The invention relates to a method of embedding a watermark W in an information signal P, to a corresponding arrangement for embedding a watermark W in an information signal P, to an information signal with an embedded watermark, and to a storage medium 50 having stored thereon an information signal P with an embedded watermark W. The watermark is embedded in the information signal by deriving sub-patterns Wi from said watermark pattern W, wherein the energy spectrum concentration of each sub-pattern Wi has a dominent orientation. The local weight factors &lgr;(P) for said watermark sub-patterns Wi are determined based on the local energy spectrum of the information signal P in said dominent orientation. Said watermark sub-patterns Wi are locally weighted using said determined local weight factors &lgr;(P). Finally, the locally weighted watermark sub-patterns (Wi) are added to the information signal P.

Abstract: The invention relates to a method of embedding a watermark W in an information signal P, to a corresponding arrangement for embedding a watermark W in an information signal P, to an information signal P with an embedded watermark W and to a storage medium 50 having stored thereon an information signal P with an embedded watermark W. This method is carried out by determining local weight factors &lgr;(P) for said watermark based on data of said information signal P, wherein said local weight factors &lgr;(P) are determined such that the embedded watermark W is rendered substantially imperceptible when embedded in said information signal. The watermark W is locally weighted using said determined local weight factors &lgr;(P). Then said locally weighted watermark is embedded in said information signal P. When determining said local weight factors &lgr;(P) of said watermark W temporal data of said information signal are taken into account.

Abstract: A method and arrangement are disclosed for distributing multimedia content such that that the actual distribution of said content can be monitored in an efficient and reliable manner. The invention combines the extensiveness of feature extraction and the robustness of watermarking. Characteristic features of the content, e.g. luminance distribution, are extracted (11) to constitute a signature (SIG) of the content. In addition, a watermark is embedded (12) having a payload representing an index (ID) in a database (10) in which the content to be monitored is stored. The watermark serves as an index for limiting the database search needed for monitoring the signatures.

Abstract: Disclosed is a method and arrangement for detecting a watermark in a suspect signal. Usually, a watermark is embedded by adding a watermark pattern w to a signal p with a given embedding strength s (“additive embedding”: q=p+sw). The embedded watermark is then detected by correlating (2,3) it with the suspect signal. Recently, “multiplicative embedding” has been proposed (q=p(1+sw)). In accordance with the invention, multiplicatively embedded watermarks are detected by raising (1) the signal to a power &bgr; prior to correlating it with the watermark. The power &bgr; may be fixed (e.g. &bgr;=2) or derived from a statistical analysis (5) of the signal.

Abstract: The invention relates to a method of storing data on a rewritable data storage medium, to a corresponding storage medium, to a corresponding recording apparatus and to a corresponding playback apparatus. Copy-protective measures require that on rewritable storage media some data must be stored which shall not be modifiable or erasable by consumer end products. A practical problem is the storage of large quantities of such data in a fixed data area. Typically the capacity is limited to a few bits. Meanwhile the amount of copy protection data that needs to be stored may well exceed the storage capacity available in the read-only fixed data area. The invention therefore proposes to write the copy protection data as system data in the recordable data area (4), e.g. as part of the formatting of the medium (1).

Abstract: Disclosed is a method and an arrangement for embedding a watermark in an information signal, in particular an audio signal. The method is based on modification of the magnitude (not the phase) of Fourier coefficients and does not require the original signal for detection. The embedder divides (10) the signal into frames of a given length, and subjects each frame to a Fast Fourier Transform (11). The Fourier coefficients X(k) are modified (20,21) as a function of a predetermined secret watermark W. A payload (P) is encoded in the embedded watermark by cyclically shifting (41) the watermark W by a number (v) of samples representing said payload.