Abstract: A method and arrangement for detecting a watermark embedded in an MPEG compressed signal includes a conventional MPEG decoder stripped to such an extent that a modified baseband video signal suitable for watermark detection is obtained. A plurality of pictures with the embedded watermark is accumulated (2,3,4) in the transform domain, and the inverse DCT (5) is applied to the accumulated result. Conventional watermark detection (6) is then applied to the accumulated plurality of pictures in the spatial domain.

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 invention relates to methods and apparatus for matching a query data object with a candidate data object by esetracting and comparing fingerprints of said data objects. In an embodiment of the invention apparatus comprising a fingerprint extraction module (110), a fingerprint matching module (210), a statistical module (120) and an identification module is provided. The fingerprint extraction module (110) receives an information signal forming part of a query object and constructs a query fingerprint. The fingerprint matching module (210) compares the query fingerprint to candidates stored in a database (215) to find at least on potentially best matching candidate. Meanwhile, the statistical module determines a statistical model of the query fingerprint so as to, for instance, determine the statistical distribution of certain information inside the query fingerprint.

Abstract: An improved method and arrangement for detecting a watermark in an information (e.g. image or video) signal are disclosed. The detection is more reliable and less vulnerable to image processing by partitioning the image into a sequence of blocks having a predetermined size, accumulating the blocks, computing a value indicative of the correlation of the accumulated blocks and the watermark having the predetermined size, and detecting whether the correlation value is larger than a predetermined threshold.

Abstract: A method of obtaining data associated with a content item, comprising the steps of obtaining (32) an identifier for the content item, performing (33) a database lookup to obtain the data using the identifier and submitting (37) the content item to an output (210) for processing by a human (200) if the database lookup fails to obtain the data, characterized by a step (35) of automatically classifying the content item into one of a number of classes, and by performing at least one of the other steps conditionally based upon the classification of the content item. In an embodiment the content item is submitted to the output only if (36) the database lookup fails to obtain the data and the content item was classified into one of a number of predetermined classes. Also a server (300) and a computer program product arranged to carry out the method.

Abstract: A watermark detection method is disclosed which is based on computing the cross-correlation between a suspect signal and a watermark. In order to be more robust against prolonged dominant signal components that adversely affect the correlation, the sequence of signal samples (61) to be correlated with the watermark is divided into sub-sequences (A(k)). The sub-sequences are processed, by a weighting function, to obtain modified sub-sequences (B(k)) that individually exhibit the original signal variations, but collectively (62) exhibit a flatter distribution of sample values. Dominant peaks in the signal are thereby substantially reduced.

Abstract: The invention relates to a method, a device, a client-server system as well as a computer program product and computer program element for handling digital silence when fingerprinting digital media signals. A fingerprint comprising a number of sub-fingerprints for at least a part of the digital media signal is generated, (step 42), and the influence of at least one piece of the media signal on the fingerprint is removed or changed, (step 48), which piece corresponds to digital silence. The invention in a reliable way avoids a wrong identification of media signals, such as audio signals, where digital silence is included. The invention is also easy to implement by only requiring some of the functionalities already provided in a computer.

Abstract: Disclosed is a method and arrangement for extracting a fingerprint from a multimedia signal, particularly an audio signal, which is invariant to speed changes of the audio signal. To this end, the method comprises extracting (12,13) a set of robust perceptual features from the multimedia signal, for example, the power spectrum of the audio signal. A Fourier-Mellin transform (15) converts the power spectrum into Fourier coefficients that undergo a phase change only if the audio playback speed changes. Their magnitudes or phase differences (16) constitute a speed change-invariant fingerprint. By a thresholding operation (19), the fingerprint can be represented by a compact number of bits.

Abstract: In order to enable a data signal, such as an audio or video signal, to be marked with multiple watermarks a set of different codes or keys is used within a given application field. The set of codes/keys is known to a watermark embedder (20) and a watermark detector (22). In each watermark embedding step, whether it is a first embedding step or a subsequent embedding step, a different key is used. The embedder (22) includes a data extractor (24) for determining which key or keys has or have been used previously. A data generator (26) then selects a new key from the set of known keys.

Abstract: Fingerprints are bit strings extracted from a media signal (e.g. an audio or video clip) to identify said media signal. Typically, they are derived from a perceptual property of the signal, for example, the spectral energy distribution of an audio fragment or the luminance distribution of a video image. A method and arrangement for extracting a fingerprint is here disclosed which is robust with respect to shifts of the perceptual property. Such shifts occur, inter alia, when the fingerprint is derived from a logarithmically mapped spectral energy distribution of an audio signal and said audio signal is subjected to speed changes. According to the invention, the fingerprint is not derived from the perceptual property as such, but from its auto-correlation function.

Abstract: A method of regulating sharing of a multimedia object (200) by a device (100), comprising registering usage information for the multimedia object (200) upon sharing of the multimedia object (200), and after the registering, billing a user of the device (100) for a certain amount in accordance with the registered usage information for the multimedia object (200). Registration preferably takes place in a client (101) arranged for sharing of the multimedia object (200). The usage information could for instance comprise the number of times a multimedia object has been shared, or the duration of the object. If a sufficient number of objects have been shared, or if the total time exceeds a maximum, the client (101) reports the usage information to a third party (130) for billing purposes.

Abstract: Methods and apparatus are described for matching a set input fingerprint blocks, each fingerprint block representing at least a part of an information signal, with fingerprints stored in a database that identify respective information signals. The method includes selecting a first fingerprint block of the set of input fingerprint blocks (10), and finding at least one fingerprint block in the database that matches the selected fingerprint block (20, 40). A further fingerprint block is then selected from the set of input blocks (60), at a predetermined position from the first selected fingerprint block. A corresponding fingerprint block is then located in the database at the same predetermined position relative to the found fingerprint block (70), and it is determined if the located fingerprint block matches the selected further fingerprint block (80).

Abstract: Method and apparatus for generating a hash signal representative of a multimedia signal are described. The method includes receiving a bit-stream comprising a compressed multimedia signal, selectively reading from the bit-stream predetermined parameters, and deriving a hash function from the parameters.

Abstract: A digital media recorder and method of controlling such is shown. During attempts to copy media content such as audio or a video sequences, sub-sequences are extracted from an input media sequence. A digital fingerprint of the sub-sequence is calculated and compared with at least one first reference fingerprint from a database. The outcome of the comparison determines the action to take in the further processing. Recording of the input media sequence on the media carrier is either allowed or obstructed, e.g. disallowed. In the case recording of the sequence is allowed, the database is updated with information that the digital media sequence has been recorded. This has the effect of a “speed bump,” which limits the rate at which those copies of media content can be made, i.e. the effect is that of prohibiting more than a given number of copies within a given time frame.

Abstract: When a client requests metadata for a multimedia object, a server (120) computes a fingerprint for the multimedia object and matches it against entries stored in a primary database (121). Additionally, the server system (120) monitors one or more transmission channels such as radio broadcast channels, and computes transmission fingerprints for transmissions on those channels. The transmission fingerprints are matched with the fingerprints stored in the primary database (121), and if a match is found, an entry for the identified transmission is then added to the secondary database (122). Preferably this entry contains the transmission fingerprint. Subsequent matches are then first performed against the secondary database (122) and only upon unsuccessful matches also matched against the primary database (121). Also covers the method and a computer program product for performing the method.

Abstract: A robust fingerprinting system is disclosed. Such a system can recognize unknown multimedia content (U(t)) by extracting a fingerprint (a series of hash words) from said content, and searching a resembling fingerprint in a database in which fingerprints of a plurality of known contents (K(t)) are stored. In order to more efficiently store the fingerprints in the database and to speed up the search, the hash words (H(n)) of known signals (K(t)) are sub-sampled (13) by a factor M prior to storage in the database (14). The hash words (H(n)) of unknown signals (U(t)) are divided (16) into M interleaved sub-series (H0(n) . . . HM?1(n)). The interleaved sub-series are selectively (17) applied to the database (14) under the control of a computer (15). If only one of the sub-series sufficiently matches a stored fingerprint, the signal is identified.

Abstract: Watermark embedding is often used to identify multiple copies (Qi) of the same content (Q). Each copy (Qi) is provided with a different private watermark (Wi) which, for example, identifies the player on which that copy may be reproduced. Private watermarks can be hacked. Averaging two or more watermarked copies may cause any of the private watermarks to become undetectable. The watermark embedder (10) in accordance with the invention embeds a global (fixed) watermark (W) in addition to the private watermark (Wi). The global watermark is the same in each copy and therefore remains detectable. Its presence indicates that a private watermark shall be present as well. It can be used in a protocol like: no playback allowed if the global watermark is present and a private watermark is not found.

Abstract: A method of maintaining a database comprising a fingerprint of and an associated set of metadata for each of a number of multimedia objects. Respective portions (201, 202, 203, 204, 205) of the database are distributed over respective file sharing clients (101-105) connected to a file sharing network (100) arranged for sharing said number of multimedia objects. File sharing clients (101-105) can maintain their own respective portions (201-205) of the database, or transmit fingerprints and metadata to another file sharing client. In the latter case, the other file sharing client is preferably a supermode in the file sharing network (100).

Abstract: An improved method and arrangement for detecting a watermark in an information (e.g. image or video) signal are disclosed. The detection is more reliable and less vulnerable to image processing by partitioning the image into a sequence of blocks having a predetermined size, accumulating the blocks, computing a value indicative of the correlation of the accumulated blocks and the watermark having the predetermined size, and detecting whether the correlation value is larger than a predetermined threshold.

Abstract: An improved method and arrangement for detecting a watermark in an information (e.g. image or video) signal are disclosed. The detection is more reliable and less vulnerable to image processing by partitioning the image into a sequence of blocks having a predetermined size, accumulating the blocks, computing a value indicative of the correlation of the accumulated blocks and the watermark having the predetermined size, and detecting whether the correlation value is larger than a predetermined threshold.