Abstract: A video decoder includes one or more processors that are configured to: determine that a picture is in a 4:4:4 color sampling format, determine, based at least in part on an index signaled in a data stream, a matrix-based intra prediction (MIP) mode, decode a luma block of the picture using the MIP mode, determine, for a chroma block of the picture, whether a coding tree of the chroma block is a single tree, select an intra prediction mode for decoding the chroma block, and decode the chroma block using the selected intra prediction mode. The selected intra prediction mode is the MIP mode in response to the coding tree of the chroma block being the single tree, and the selected intra prediction mode is a planar intra prediction mode in response to the coding tree of the chroma block not being the single tree.

Abstract: A further coding efficiency increase may be achieved if for a current block of a picture, for which the bit stream signals one of supported partitioning patterns, a reversal of the partitioning by block merging is avoided. In particular, if the signaled one of the supported partitioning patterns specifies a subdivision of the block into two or more further blocks, a removal of certain coding parameter candidates for all further blocks, except a first further block of the further blocks in a coding order, is performed. Particularly, those coding parameter candidates are removed from the set of coding parameter candidates for the respective further block, the coding parameters of which are the same as coding parameters associated with any of the further blocks which, when being merged with the respective further block, would result in one of the supported partitioning pattern. This avoids redundancy between partitioning coding and merging coding.

Abstract: A coding efficiency increase is achieved by using a common signalization within the bitstream with regard to activation of merging and activation of the skip mode. One possible state of one or more syntax elements within the bitstream may signalize for a current sample set of a picture that the sample set is to be merged and has no prediction residual encoded and inserted into the bitstream. A common flag may signalize whether the coding parameters associated with a current sample set are to be set according to a merge candidate or to be retrieved from the bitstream, and whether the current sample set of the picture is to be reconstructed based on a prediction signal depending on the coding parameters associated with the current sample set, without any residual data, or to be reconstructed by refining the prediction signal depending on the coding parameters associated with the current sample set by means of residual data within the bitstream.

Abstract: A better compromise between encoding complexity and achievable rate distortion ratio, and/or to achieve a better rate distortion ratio is achieved by using multitree sub-divisioning not only in order to subdivide a continuous area, namely the sample array, into leaf regions, but using the intermediate regions also to share coding parameters among the corresponding collocated leaf blocks. By this measure, coding procedures performed in tiles—leaf regions—locally, may be associated with coding parameters individually without having to, however, explicitly transmit the whole coding parameters for each leaf region separately. Rather, similarities may effectively exploited by using the multitree subdivision.

Abstract: A video encoder for encoding a video into a data stream using motion compensated prediction for inter predicted blocks, comprising a hypothesis number control, configured to control a number of prediction hypotheses of the inter predicted blocks within a predetermined portion of the video to meet a predetermined criterion.

Abstract: A video encoder for encoding a video into a data stream using motion compensated prediction for inter predicted blocks, comprising a hypothesis number control, configured to control a number of prediction hypotheses of the inter predicted blocks within a predetermined portion of the video to meet a predetermined criterion.

Abstract: An apparatus for block-wise decoding a picture from a data stream and/or encoding a picture into a data stream, the apparatus supporting at least one intra-prediction mode according to which the intra-prediction signal for a block of a predetermined size of the picture is determined by applying a first template of samples which neighbours the current block onto a neural network. The apparatus may be configured, for a current block differing from the predetermined size, to: resample a second template of samples neighboring the current block, so as to conform with the first template so as to obtain a resampled template; apply the resampled template of samples onto the neural network so as to obtain a preliminary intra-prediction signal; and resample the preliminary intra-prediction signal so as to conform with the current block so as to obtain the intra-prediction signal for the current block.

Abstract: Techniques for block wise encoding and decoding may be applied to encoders, decoders, and methods for encoding or decoding and include assigning, based on a first signalization in the data stream, the predetermined block to the first set or the second set, sorting the assigned set of intra-prediction modes according to intra-prediction modes used for neighboring blocks, neighboring the predetermined block, to obtain a list of intra prediction modes, deriving, for the predetermined block, from the data stream, an index into the list of intra prediction modes, predicting the predetermined block using an intra prediction mode onto which the index points. The decoder or encoder, if the assigned set is the first set of intra-prediction modes, in sorting the assigned set, uses a second mapping which maps each intra-prediction mode of the second set of prediction modes onto a representative one in the first set of intra-prediction modes.

Abstract: A favorable merging or grouping of simply connected regions into which the array of information samples is sub-divided, is coded with a reduced amount of data. To this end, a predetermined relative locational relationship is defined enabling an identifying, for a predetermined simply connected region, of simply connected regions within the plurality of simply connected regions which have the predetermined relative locational relationship to the predetermined simply connected region. Namely, if the number is zero, a merge indicator for the predetermined simply connected region may be absent within the data stream In other embodiments, spatial sub-division is performed depending on a first subset of syntax elements, followed by combining spatially neighboring simply connected regions depending on a second subset of syntax elements, to obtain an intermediate sub-division.

Abstract: An apparatus includes at least one processor for decoding a block of a picture using intra-prediction that is configured to: decode, from a data stream, a mode index, the mode index indicating a matrix-based intra-prediction mode out of a plurality of matrix-based intra-prediction modes based on a size of the block, derive an input vector based on downsampling reference samples neighboring the block, determine a matrix based on the size of the block and the mode index, compute a respective output for each component of a matrix-vector product between the the input vector and the determined matrix, the respective output computed by performing, a right shift by a number of bits which is independent of the matrix-based intra-prediction mode indicated by the mode index, and for each component of the matrix-vector product, use the respective output to predict a respective sample of the block.

Abstract: Apparatus configured to derive a set-selective syntax element indicating whether the predetermined block is to be predicted using one of a first set of intra-prediction modes comprising a DC intra prediction mode and angular prediction modes. If the set-selective syntax element indicates that the predetermined block is to be predicted using one of the first set of intra-prediction modes, the apparatus is configured to use a list of most probable intra-prediction modes. If the set-selective syntax element indicates that the predetermined block is not to be predicted using one of the first set of intra-prediction modes, the apparatus is configured to use a matrix-based intra-prediction mode. The list of most probable intra-prediction modes is formed such that the list of most probable intra-prediction modes is free of the DC intra prediction mode in case of the neighbouring blocks being predicted by any of the angular intra prediction modes.

Abstract: A method for decoding a predetermined block of a picture using intra-prediction by reading, for each of predetermined intra-prediction blocks, from a data stream, a mode index identifying a matrix-based intra-prediction mode is disclosed. Samples of each predetermined intra-prediction block are predicted by computing a matrix-vector product between an input vector derived from reference samples and a prediction matrix associated with the identified matrix-based intra-prediction mode (k)-and associating components of an output vector obtained by the matrix-vector product onto sample positions of the predetermined block. Further predetermined intra-predicted blocks of the picture are predicted to obtain a prediction signal. A transformation flag is decoded from the data stream using context adaptive binary arithmetic coding, and a prediction residual is decoded and re-transformed using a reverse transformation based on the transformation flag to obtain a prediction residual signal.

Abstract: An apparatus includes an encoder, which receives image or video data, encodes the data and provides a bitstream. The encoder includes a CABAC encoder, which receives a binary valued syntax element associated with a block of the data to be encoded, and encodes, using a selected context model, the syntax element into coded bits for the bitstream. The syntax element includes a tool flag indicating whether or not certain coding tool is employed when encoding a block of the data. For a block of the data which exhibits an aspect ratio larger than 2 and for a block of the data which exhibits an aspect ratio less than or equal to 2, and to which blocks the certain coding tool is applicable, first and second context models for encoding the tool flag are selected from a group of one or more first and second context models, respectively.

Abstract: Coding schemes for coding a spatially sampled information signal using subdivision and coding scheme for coding a sub-division or a multi tree structure are described, wherein representative embodiments relate to picture and/or video coding applications.

Abstract: Coding efficiency increases are achieved by using composed prediction signals to predict a predetermined block of a picture.

Abstract: A coding efficiency increase is achieved by using a common signalization within the bitstream with regard to activation of merging and activation of the skip mode. One possible state of one or more syntax elements within the bitstream may signalize for a current sample set of a picture that the sample set is to be merged and has no prediction residual encoded and inserted into the bitstream. A common flag may signalize whether the coding parameters associated with a current sample set are to be set according to a merge candidate or to be retrieved from the bitstream, and whether the current sample set of the picture is to be reconstructed based on a prediction signal depending on the coding parameters associated with the current sample set, without any residual data, or to be reconstructed by refining the prediction signal depending on the coding parameters associated with the current sample set by means of residual data within the bitstream.

Abstract: In accordance with a first aspect, an improved compression efficiency is achieved by letting a block-wise picture codec support a set of intra-prediction modes according to which the intra-prediction signal for a current block of a picture is determined by applying a set of neighboring samples of the current block onto a neural network. A second aspect of the present application is that, additionally or alternatively to the spending of neural network-based intra-prediction modes, the mode selection may be rendered more effective by the usage of a neural network dedicated to determine a rank or a probability value for each of the set of intra-prediction modes by applying a set of neighboring samples thereonto with the rank or probability value being used for the selection of one intra-prediction mode out of the plurality of intra-prediction modes including or coinciding with the set of intra-prediction modes.

Abstract: In transform coefficient coding, predetermined sets of transforms may be used. Embodiments of the present invention provide an encoder and a decoder for encoding a picture into/from a data stream using block-based prediction and block-based residual coding, the encoder and decoder supporting a set of transforms for the block-based residual coding. The encoder and decoder are configured to determine a transform candidate list of transforms for a current residual block out of the set of transforms based on a height and a width of the current residual block, and to encode/decode a prediction residual within the residual block using one selected transform out of the selectable list of transforms and selectively signal/derive the selected transform in/from the data stream.

Abstract: A further coding efficiency increase may be achieved if for a current block of a picture, for which the bit stream signals one of supported partitioning patterns, a reversal of the partitioning by block merging is avoided. In particular, if the signaled one of the supported partitioning patterns specifies a subdivision of the block into two or more further blocks, a removal of certain coding parameter candidates for all further blocks, except a first further block of the further blocks in a coding order, is performed. Particularly, those coding parameter candidates are removed from the set of coding parameter candidates for the respective further block, the coding parameters of which are the same as coding parameters associated with any of the further blocks which, when being merged with the respective further block, would result in one of the supported partitioning pattern. This avoids redundancy between partitioning coding and merging coding.

Abstract: Coding schemes for coding a spatially sampled information signal using sub-division and coding schemes for coding a sub-division or a multitree structure are described, wherein representative embodiments relate to picture and/or video coding applications.