Abstract: A data encoding method comprises generating one or more encoding parameters; communicating the one or more encoding parameters for use by a decoding process; and encoding data items representing image data samples of an image by generating residual data indicative of a difference between an image data sample and a predicted version of that image data sample, the encoding step performing the encoding in dependence upon the one or more encoding parameters generated by the generating step; in which the generating step comprises deriving an estimate of the residual data in respect of at least a subset of the image data samples and generating the one or more encoding parameters in dependence upon the derived estimate.

Abstract: An apparatus includes a video data decoder and a coded picture buffer to buffer successive portions of an input video data and provide a portion to the video data decoder for decoding. The video data decoder is responsive to parameter data associated with the input video data. The parameter data indicates, for a given input video data, an encoding level selected from a plurality of encoding levels. Each level defines at least a maximum luminance picture size, a minimum compression ratio, and a maximum value of the coded picture buffer size. For each encoding level of the plurality of encoding levels, the maximum value of the coded picture buffer size is greater than or equal to the number of bits required to represent a picture at the maximum luminance picture size when encoded according to the minimum compression ratio.

Abstract: Image data encoding and/or decoding apparatus comprises an inter-image predictor configured to predict samples of a current image region, of a plurality of regions of an image in a sequence of images, with respect to a reference image region of another, reference, image of the sequence of images, according to a direction vector indicating a spatial displacement of the reference image region from the current image region; an interpolation filter configured to generate the predicted samples of the current image region by spatial interpolation of samples of the reference image region, at least in instances where the direction vector indicates a spatial displacement of a non-integer number of samples, in which the interpolation filter is configured to operate according to a set of filter parameters each defining the spatial frequency response of a set of filters providing interpolation at a spatial displacement resolution of 1/m sample, where m is an integer greater than one; and a filter response selector config

Abstract: An image encoding apparatus comprises a controller configured to select, from a set of prediction directions, a set of candidate prediction directions as a subset of the set of prediction directions, for a current image region of a current image in dependence upon one or more properties of a group of reference samples of the current image applicable to the current image region; and an intra-image predictor configured to predict samples of the current image region with respect to one or more of the group of reference samples of the same image according to a prediction direction between the current sample and a reference position amongst the reference samples; in which the intra-image predictor is configured to select the prediction direction for the current image region from the set of candidate prediction directions.

Abstract: Image data encoding and/or decoding apparatus comprises an inter-image predictor configured to predict samples of a current image region, of a plurality of regions of an image in a sequence of images, with respect to a reference image region of another, reference, image of the sequence of images, according to a direction vector indicating a spatial displacement of the reference image region from the current image region; an interpolation filter configured to generate the predicted samples of the current image region by spatial interpolation of samples of the reference image region, at least in instances where the direction vector indicates a spatial displacement of a non-integer number of samples, in which the interpolation filter is configured to operate according to a set of filter parameters each defining the spatial frequency response of a set of filters providing interpolation at a spatial displacement resolution of 1/m sample, where m is an integer greater than one; and a filter response selector config

Abstract: A method of encoding video data values, the method including selectively encoding, via circuitry, a high bit depth control flag and, when the high bit depth control flag is set to indicate high bit depth operation, selectively encoding an extended precision flag to indicate at least extended precision operation of a spatial frequency transform stage and encoding the video data values according to a mode of operation defined by the encoded high bit depth control flag and, when encoded, the extended precision flag.

Abstract: Image data encoding apparatus comprises an entropy encoder configured to selectively encode data items representing image data by an encoding system selected from a context adaptive binary arithmetic coding (CABAC), encoding system and a bypass encoding system; in which the data items include (i) a first data item indicating whether a multi-direction linear model (MDLM) chroma mode applies to a current image region; and (ii) a second data item indicating a processing direction for operation of the MDLM chroma mode; in which the entropy encoder is configured to encode instances of the first data item and to encode instances of the second data item independently of the encoding of instances of the first data item.

Abstract: Apparatus comprises video data decoder circuitry configured to decode an input video data stream, the video data decoder being responsive to parameter data associated with the input video data stream, the parameter data indicating a profile selected from a plurality of profiles, each profile defining a decoding attribute comprising one or more of a bit depth and a chrominance subsampling format; detector circuitry configured to detect constraint data associated with the input video data stream, the constraint data defining a difference between a decoding attribute applicable to the input video data stream and the decoding attribute defined by the profile indicated by the parameter data, in which the constraint data is configured to indicate a zero difference of the decoding attribute by a zero value of the constraint data; and control circuitry configured to control the video data decoder to decode the input video data stream to generate a decoded video data stream having a decoding attribute defined by the e

Abstract: A method of encoding video data values, the method including selectively encoding, via circuitry, a high bit depth control flag and, when the high bit depth control flag is set to indicate high bit depth operation, selectively encoding an extended precision flag to indicate at least extended precision operation of a spatial frequency transform stage and encoding the video data values according to a mode of operation defined by the encoded high bit depth control flag and, when encoded, the extended precision flag.

Abstract: Am image data encoding apparatus includes an entropy encoder to encode data items representing image data by an encoding system using a context adaptive binary arithmetic coding (CABAC) encoding system and a bypass encoding system. The data items include a first data item indicating whether a multi-direction linear model (MDLM) chroma mode applies to a current image region, and a second data item indicating a processing direction for operation of the MDLM chroma mode. The entropy encoder encodes instances of the first data item and instances of the second data item using different encoding systems.

Abstract: Image data encoding apparatus comprises an entropy encoder for selectively encoding data items representing image data to be encoded by a first, context adaptive binary arithmetic coding (CABAC), encoding system or by a second, bypass, encoding system, so as to generate encoded binarized symbols; the image data representing one or more pictures of a picture sequence, each picture comprising two or more output data units representing respective sub-sections of the picture, each sub-section being decodable and reconstructable independently of other sub-sections in that picture and picture sequence; the entropy encoder being configured to generate an output data stream subject to a constraint defining an upper limit to the number of binarized symbols that may be expressed by any individual output data unit relative to the size in bytes of that output data unit, in which the entropy encoder is configured to apply the constraint to each output data unit, and to provide padding data, for each output data unit which

Abstract: Image data encoding apparatus, comprises an entropy encoder configured to selectively encode data items representing image data so as to generate encoded binarized symbols of successive output data units; the entropy encoder being configured to generate an output data stream subject to a constraint defining an upper limit to the number of binarized symbols that may be expressed by any individual output data unit relative to the size in bytes of that output data unit, in which the entropy encoder is configured to provide padding data, for each output data unit which does not meet the constraint, so as to increase the size in bytes of that output data unit in order to meet the constraint; the apparatus comprising: an attribute detector configured to detect an encoding attribute applicable to a given output data unit; and a selector configured to select, in response to the detected encoding attribute, a constraint, for use with the given output data unit, from two or more candidate constraints.

Abstract: Image data encoding apparatus comprises an entropy encoder for selectively encoding data items representing image data to be encoded by a first, context adaptive binary arithmetic coding (CABAC), encoding system or by a second, bypass, encoding system, so as to generate encoded binarized symbols; the image data representing one or more pictures of a picture sequence, each picture comprising two or more output data units representing respective sub-sections of the picture, each sub-section being decodable and reconstructable independently of other sub-sections in that picture and picture sequence; in which each sub-section is subject to a respective minimum compression ratio.

Abstract: A method of encoding successive data items comprises storing history data for encoded data items, the history data indicating one or more aspects of encoding the encoded data items; encoding a given data item by a first encoding technique comprising encoding a series of zero or more data sets, each data set representing a respective range of values of the data items and selecting the series of data sets from a plurality of candidate data sets in dependence upon (i) a number of previously encoded data sets; and (ii) the history data applicable to a given property of the given data item; and encoding any remaining value of the given data item, the remaining value being an amount by which the given data item exceeds a maximum value which can be encoded by the first encoding technique, by a second encoding technique different to the first encoding technique.

Abstract: Image data encoding apparatus comprises an entropy encoder for selectively encoding data items representing image data to be encoded by a first, context adaptive binary arithmetic coding (CABAC), encoding system or by a second, bypass, encoding system, so as to generate encoded binarized symbols; the image data representing one or more pictures of a picture sequence, each picture comprising two or more output data units representing respective sub-sections of the picture, each sub-section being decodable and reconstructable independently of other sub-sections in that picture and picture sequence; the entropy encoder being configured to generate an output data stream subject to a constraint defining an upper limit to the number of binarized symbols that may be expressed by any individual output data unit relative to the size in bytes of that output data unit, in which the entropy encoder is configured to apply the constraint to each output data unit, and to provide padding data, for each output data unit which

Abstract: An apparatus including a video data decoder configured to decode an input video data stream, the video data decoder being responsive to a parameter value associated with the input video data stream, the parameter value indicating an encoding level selected from a plurality of encoding levels, each encoding level defining at least a maximum luminance picture size and a maximum luminance sample rate, the encoding level defining a first numerical component and a second numerical component, the second numerical component being a numerical value greater than or equal to zero, in which for encoding levels having a second numerical component of zero, the first numerical component increases monotonically with increasing maximum luminance picture size, and the second component varies with the maximum luminance sample rate; the parameter value being a numeric encoding of the encoding level.

Abstract: An image encoding apparatus comprises a selector configured to select, from a set of candidate prediction operations each defining at least a prediction direction, a prediction operation for prediction of samples of a current region of a current image, the current region comprising an array of two or more rows and two or more columns of samples; an intra-image predictor configured to derive predicted samples of the current region with respect to one or more of a group of reference samples of the same image in dependence upon a prediction direction, defined by the selected prediction operation, between a current sample to be predicted and a reference position amongst the reference samples; in which, for at least some of the candidate prediction operations, the group of reference samples comprises two or more parallel linear arrays of reference samples disposed at different respective separations from the current region; a detector configured to detect whether samples corresponding to any of the two or more par

Abstract: A data encoding method comprises generating one or more encoding parameters; communicating the one or more encoding parameters for use by a decoding process; and encoding data items representing image data samples of an image by generating residual data indicative of a difference between an image data sample and a predicted version of that image data sample, the encoding step performing the encoding in dependence upon the one or more encoding parameters generated by the generating step; in which the generating step comprises deriving an estimate of the residual data in respect of at least a subset of the image data samples and generating the one or more encoding parameters in dependence upon the derived estimate.

Abstract: A method of encoding successive data items comprises storing history data for encoded data items, the history data indicating one or more aspects of encoding the encoded data items; encoding a given data item by a first encoding technique comprising encoding a series of zero or more data sets, each data set representing a respective range of values of the data items and selecting the series of data sets from a plurality of candidate data sets in dependence upon (i) a number of previously encoded data sets; and (ii) the history data applicable to a given property of the given data item; and encoding any remaining value of the given data item, the remaining value being an amount by which the given data item exceeds a maximum value which can be encoded by the first encoding technique, by a second encoding technique different to the first encoding technique.

Abstract: A video data encoding method for encoding an array of video data values comprises the steps of: frequency-transforming the video data values according to a frequency transform, to generate an array of frequency-transformed values by a matrix-multiplication process using a transform matrix having a data precision of fourteen bits, the frequency transform being a discrete cosine transform; defining a 64×64 transform matrix M64 for a 64×64 DCT transform, the matrix M64 being defined by the accompanying FIGS. 10a-10e and 11; for an N×N transform where N is 2, 4, 8 or 16, subsampling the 64×64 transform matrix M64 to select a subset of N×N values, the subset MN[x][y] of values being defined by: MN[x][y]=M64[x][(2(6-log2(N)))y] for x,y=0 . . . (N?1).