Abstract: Apparatus arranged to perform data multiplexing or demultiplexing or a non-transitory computer readable medium comprising a computer program which, when executed by a computer, carries out a method of multiplexing or demultiplexing data, the apparatus comprising a memory, an interface, and a processing unit arranged to determine locations of corresponding regions of the memory for corresponding channels based on data sizes and time-unit-numbers that have passed since a previous corresponding quantity of channel data for a corresponding channel was last stored in the memory or processed, wherein the data sizes and time-unit numbers correspond to one or more channels of the plurality of channels, such that the processing unit will not store the corresponding quantity of the channel data, for each corresponding channel of the plurality of channels, at a location in the memory that is currently storing any channel data that has not yet been output or processed.

Abstract: Apparatus arranged to perform data multiplexing or demultiplexing or a non-transitory computer readable medium comprising a computer program which, when executed by a computer, carries out a method of multiplexing or demultiplexing data, the apparatus comprising a memory, an interface, and a processing unit arranged to determine locations of corresponding regions of the memory for corresponding channels based on data sizes and time-unit-numbers that have passed since a previous corresponding quantity of channel data for a corresponding channel was last stored in the memory or processed, wherein the data sizes and time-unit numbers correspond to one or more channels of the plurality of channels, such that the processing unit will not store the corresponding quantity of the channel data, for each corresponding channel of the plurality of channels, at a location in the memory that is currently storing any channel data that has not yet been output or processed.

Abstract: A method of demultiplexing data, the method comprising: during each of a series of time-units, receiving multiplexed data, wherein the multiplexed data comprises, for each of a plurality of channels, a corresponding quantity of channel data of a corresponding data size; and during each of the series of time-units, for each of the plurality of channels, storing the corresponding quantity of channel data received during that time-unit in a contiguous region of a memory associated with that channel; wherein each of the plurality of channels has a corresponding time-unit-number such that, for each of the plurality of channels, the channel data stored in the corresponding region of the memory for that channel is to be processed after a number of time units equal to the time-unit-number for that channel has passed since channel data for that channel was last processed; characterized in that the method comprises: determining the locations of the regions of the memory based on the data sizes and the time-unit-numbers

Abstract: A method of demultiplexing data, the method comprising: during each of a series of time-units, receiving multiplexed data, wherein the multiplexed data comprises, for each of a plurality of channels, a corresponding quantity of channel data of a corresponding data size; and during each of the series of time-units, for each of the plurality of channels, storing the corresponding quantity of channel data received during that time-unit in a contiguous region of a memory associated with that channel; wherein each of the plurality of channels has a corresponding time-unit-number such that, for each of the plurality of channels, the channel data stored in the corresponding region of the memory for that channel is to be processed after a number of time units equal to the time-unit-number for that channel has passed since channel data for that channel was last processed; characterised in that the method comprises: determining the locations of the regions of the memory based on the data sizes and the time-unit-numbers

Abstract: An image processing apparatus is operable to embed data into an image. Images such as those generated from an inter-laced scan may comprise a frame of image data, the frame comprising first and second image fields. The image processing apparatus comprises a combining processor operable to introduce the data to be embedded into at least one of the first and second fields of the image frame. As such a likelihood of a perceivable effect of the embedded data on the image may be reduced, because the images are viewed as a frame. The embedded data may also have an increased likelihood of being detected because some processing may effect the image frame more then the fields of the image. The combining processor may be operable to represent the data to be embedded in a transform domain form, and, in combination with a transform processor, combine the data to be embedded with the first and/or second fields with the image in a transform domain form or a spatial domain form.

Abstract: A method of controlling copying of an information signal, comprises the steps of: prior to recordal and/or transmission, applying to the information signal a substantially imperceptible modification representing copy control data including a password securely encoded according to a predetermined algorithm; upon reproduction for copying by a user, deriving (S1, S3) the copy control data from the modified information signal; comparing (S8, S9, S11, S13, S15) the derived securely encoded password with a reference password securely encoded according to a predetermined algorithm; and enabling (S5) copying of the information signal if the securely encoded password derived from the information signal and the securely encoded reference password have a predetermined relationship, otherwise disabling copying (S7). The reference password is sent to the user via a channel which is separate from a channel used to send the information signal to the user.

Abstract: An apparatus for embedding data in information material, the data being a plurality of data items each having a different relative importance. The apparatus comprises an encoding processor operable to encode each of said data items, and a combining processor operable to combine said encoded data items with said information material. The information material provides a limited data embedding capacity, as a result for example of the limited bandwidth of the information material itself. Each of the data items are encoded and embedded to the effect that a proportion of the limited data embedding capacity is allocated to the encoded data items in accordance with the relative importance of these data items. As such, for example, an amount of error protection given to each of the data items can be arranged in accordance with the importance of the data items, whilst still satisfying the limited data embedding capacity.

Abstract: The bitstream includes digital codes representing an information signal. At least one digital code is selected. The code occupies a part of the bitstream which is to contain at least one watermark code which represents a watermark perceptible in the information signal. The selected digital code(s) are removed from the said part of the bitstream. The watermark code(s) are put in the said part of the bitstream in place of the selected code(s). The number of bits of the selected code(s) removed from the said part of the bitstream is greater than or equal to the number of bits of the said watermark code(s) put in the said part. The removed selected code(s) are appended to an end of the bitstream and/or placed in watermark user data fields created in the bitstream.

Abstract: A method of embedding data in material comprises the steps of: embedding data in original material to produce data embedded material; removing the watermark from the data embedded material to produce recovered material; comparing the original and recovered material to determine the differences and locations of differences therebetween; and storing the said locations and corrections which correct the said differences. A method of removing the data embedded in the material, comprises the steps of: removing the data from the material to produce recovered material; deriving the said corrections and locations from the said store; and using the corrections to correct the recovered material at the said locations.

Abstract: A recording arrangement is provided for applying access control processing to input data content and for recording access-controlled data content on a content storage medium. The recording arrangement comprises an encryption apparatus for encrypting portions of the input data content and an access control memory device operable to securely store information from which a private key of a public key/private key pair associated with a data content recording user or user group is derivable. The encryption apparatus and the access control memory device co-operate to provide means for generating access control data comprising content recorder access control data and default access control data. The default content access control data providing the same level of access to the input data content as the level of access available to the data content recording user/user group. A recording means is provided for recording the encrypted input data content and the content access control data on the content storage medium.

Abstract: A recording apparatus operable to apply access control processing to input data content using a set of one or more content keys and to record access-controlled data content on a content storage medium on which a read-only medium identifier is stored comprises: means for encrypting portions of the data content in dependence upon the set of content keys; means for generating content access control data so that decryption of the information content requires access to the read-only medium identifier, the content access control data comprising at least one encrypted version of a respective subset of the set of content keys; and means for recording the encrypted data content and the content access control data on the content storage medium.

Abstract: Data recording apparatus in which content data is recorded as a set of successive data portions in a recording order on a linear-access recording medium, the set of data portions being access-controlled in dependence upon reference data comprises means for recording the reference data and the set of access-controlled data portions on the linear-access recording medium, the recording means being operable to record the reference data at a reference data position on the linear-access recording medium, and to record location information with at least some of the data portions in the set, the location information defining the position on the linear-access recording medium of the reference data relevant to that data portion.

Abstract: A data storage arrangement is provided and is operable to apply access control processing to input data in dependence upon a public key of a public key/private key pair. The arrangement comprises an encrypting apparatus and a plurality of removable memory devices connectable to the encrypting apparatus via an interface. The encrypting apparatus stores a local copy of a user director which is identified by a local version identification tag and lists a user identifier and an associated public key for each of a plurality of authorised users. Each removable memory device securely stores an external copy of the user directory. The encryption apparatus also has encryption means for encrypting at least portions of the input data content in dependence on a public key derived from either the local or the external user directory.

Abstract: A recording arrangement operable to apply access control processing to input data content using a set of one or more content keys and to record access-controlled data content on a content storage medium, the arrangement comprising: an encryption apparatus having means for encrypting portions of the data content in dependence upon the set of content keys; and an interface to provide a secure data connection between the encryption apparatus and an access control memory device; an access-control memory device connected to the encryption apparatus via the interface and operable to store securely information from which the private key is derivable; the encryption apparatus and the access-control memory device co-operating to provide means for generating content access control data comprising at least one encrypted version of a respective subset of the set of content keys, the content access control data being generated in dependence upon at least one public key of a respective public key/private key pair associate

Abstract: A method of detecting a version of input data content, there being a plurality of different versions of said data content, in which: said data content is arranged as two or more segments according to a segmentation pattern; and said versions of said data content are identifiable by corresponding identification data patterns by which at least some of said segments have respective identification data; said method comprising the steps of: (i) detecting said identification data in respect of said segments of said input data content; (ii) comparing said detected identification data with said identification data patterns corresponding to said different versions of said data content; and (iii) detecting that said input data content comprises at least a contribution from a certain version of said data content if a sum of matches obtained between said detected identification data and said identification data pattern for said certain version exceeds a threshold number.

Abstract: Data coding apparatus in which input data having a range of possible data values and a smaller sub-range of legal data values is coded by applying a coder mapping which maps input data values in the range of possible input data values and corresponding coded data values within the range of possible data comprises means for detecting, for each coded data value, whether the coded data value lies within the sub-range of legal data values; and means for remapping a coded data value lying outside the sub-range of legal data values to an unused coded data value lying within the sub-range of legal data values.

Abstract: An image processing apparatus is operable to embed data into an image. Images such as those generated from an inter-laced scan may comprise a frame of image data, the frame comprising first and second image fields. The image processing apparatus comprises a combining processor operable to introduce the data to be embedded into at least one of the first and second fields of the image frame. As such a likelihood of a perceivable effect of the embedded data on the image may be reduced, because the images are viewed as a frame. The embedded data may also have an increased likelihood of being detected because some processing may effect the image frame more then the fields of the image. The combining processor may be operable to represent the data to be embedded in a transform domain form, and, in combination with a transform processor, combine the data to be embedded with the first and/or second fields with the image in a transform domain form or a spatial domain form.

Abstract: An apparatus for embedding data in information material, the data being a plurality of data items each having a different relative importance. The apparatus comprises an encoding processor operable to encode each of said data items, and a combining processor operable to combine said encoded data items with said information material. The information material provides a limited data embedding capacity, as a result for example of the limited bandwidth of the information material itself. Each of the data items are encoded and embedded to the effect that a proportion of the limited data embedding capacity is allocated to the encoded data items in accordance with the relative importance of these data items. As such, for example, an amount of error protection given to each of the data items can be arranged in accordance with the importance of the data items, whilst still satisfying the limited data embedding capacity.