Abstract: An encoder includes circuitry and memory coupled to the circuitry. In operation, the circuitry: derives a motion vector of a current block by referring to at least one reference picture different from a picture to which the current block belongs; performs a mode for estimating, for each sub-block unit of sub-blocks obtained by splitting the current block, a surrounding region of the motion vector to correct the motion vector; determines whether to apply deblocking filtering to each of boundaries between neighboring ones of the sub-blocks; and applies the deblocking filtering to the boundary, based on a result of the determination.

Abstract: An encoder according to one aspect of the present disclosure encodes a block of an image, and includes a processor and memory connected to the processor. Using the memory, the processor partitions a block into a plurality of sub blocks and encodes a sub block included in the plurality of sub blocks in an encoding process including at least a transform process or a prediction process. The block is partitioned using a multiple partition including at least three odd-numbered child nodes and each of a width and a height of each of the plurality of sub blocks is a power of two.

Abstract: An encoder includes circuitry and memory connected to the circuitry. The circuitry: derives an absolute value of a sum of gradient values in first and second ranges; derives, as a first parameter, a total sum of absolute values of sums of gradient values derived respectively for pairs of relative pixel positions; derives a pixel difference value between pixel values in the first and second ranges; inverts or maintains a plus or minus sign of the pixel difference value, according to a plus or minus sign of the sum of the gradient values indicating the sum of the gradient values in the first and second ranges; derives, as a second parameter, a total sum of pixel difference values each having the plus or minus sign inverted or maintained, the pixel difference values derived respectively for the relative pixel positions; and generates a prediction image using the first and second parameters.

Abstract: A transmitting method according to one aspect of the present disclosure includes transmitting video control information for reproduction of video data having an individually reproducible unit, transmitting the video data, determining a transmission order of audio control information for reproduction of audio data in a reproduction interval corresponding to a reproduction interval of the video data in such a way that the audio control information is transmitted after the video control information, and transmitting the audio control information according to the determined transmission order, and transmitting the audio data. Thus, in the receiving apparatus, a delay time from reception of data to reproduction of video and audio is shortened.

Abstract: An image coding method of hierarchically coding a plurality of pictures to generate a bitstream, includes: coding each of the plurality of pictures, which belongs to any one of a plurality of hierarchical layers, with reference to a picture belonging to a hierarchical layer which is same as or lower than a hierarchical layer to which the picture belongs, and without reference to a picture belonging to a hierarchical layer which is higher than the hierarchical layer to which the picture belongs; and generating the bitstream by coding the coded pictures and time information indicating decoding times of the coded pictures. The time information indicates that the decoding times are set at equal intervals for low-layer pictures which are the plurality of pictures other than highest-layer pictures belonging to a highest layer among the plurality of hierarchical layers.

Abstract: Various embodiments provide a decoder configured to select a filter based on a block size of a first block and a block size of a second block in an image, and change values of pixels in the first block and the second block. The filter includes a first set of multipliers and a first set of offsets for the first block, and a second set of multipliers and a second set of offsets for the second block. The values of the pixels in the first block and the second block are changed by performing multiplication with each multiplier in the first set of multipliers, by performing multiplication with each multiplier in the second set of multipliers, and by using the first set of offsets and the second set of offsets.

Abstract: A moving picture coding apparatus includes: an inter prediction control unit which determines to code a motion vector using, among candidate predicted motion vectors, a candidate predicted motion vector having the least error with relative to a motion vector derived by motion estimation; a picture type determination unit which generates picture type information; a temporal direction vector calculation unit which derives a candidate predicted motion vector in temporal direct; and a co-located reference direction determination unit which generates, for each picture, a co-located reference direction flag.

Abstract: A moving picture coding method includes: coding a coding target block using a motion vector; generating motion vector predictors; and coding the motion vector using one of the motion vector predictors generated in the generating of the motion vector predictors. In the generating of the motion vector predictors, a replacement vector which replaces a temporal motion vector predictor is added to the motion vector predictors when it is impossible to obtain the temporal motion vector predictor from a block which is included in a coded picture different from the coding target picture and corresponds to the coding target block.

Abstract: Provided is an encoder which includes circuitry and memory. The circuitry encodes an image block using the memory. In encoding the image block, the circuitry: obtains one or more size parameters related to a size of the image block; determines whether the one or more size parameters and one or more thresholds satisfy a determined relationship; encodes a split parameter when the one or more size parameters and the one or more thresholds are determined to satisfy the determined relationship, the split parameter indicating whether the image block is to be split into a plurality of partitions including a non-rectangular partition; and encodes the image block after splitting the image block into the plurality of partitions when the split parameter indicates that the image block is to be split into the plurality of partitions.

Abstract: An encoder determines, based on a width and a height of a block, whether or not to disable a prediction mode in which the block is split along a partitioning line defined by a distance and an angle and then prediction is performed; and encodes the block with the prediction mode disabled or not disabled according to a result of the determination on whether or not to disable the prediction mode. Here, the distance is the shortest distance between the center of the block and the partitioning line, and the angle is an angle representing a direction from the center of the block toward the partitioning line in the shortest distance. The encoder determines to disable the prediction mode when (i) a width-to-height ratio is at least 8 or (ii) a height-to-width ratio is at least 8.

Abstract: An image encoding method including: a constraint information generating step of generating tile constraint information indicating whether or not there is a constraint in filtering on boundaries between adjacent tiles among a plurality of tiles obtained by dividing a picture, and storing the tile constraint information into a sequence parameter set; and a filter information generating step of generating, for each of the boundaries, one of a plurality of filter information items respectively indicating whether or not filtering is executed on the boundaries, and storing the plurality of filter information items into a plurality of picture parameter sets, wherein, in the filter information generating step, the plurality of filter information items which indicate identical content are generated when the tile constraint information indicates that there is the constraint in the filtering.

Abstract: An encoder includes circuitry and memory connected to the circuitry. In operation, the circuitry: derives an average value of motion vector values of two prediction candidates in a prediction candidate list for a merge mode, and registers the average value derived as new motion vector information of a new prediction candidate into the prediction candidate list; and derives new correction processing information regarding correction processing of a prediction image, and registers the new correction processing information derived into the prediction candidate list in association with the new motion vector information.

Abstract: The image decoding method includes determining a context for use in a current block to be processed, from among a plurality of contexts, wherein in the determining: the context is determined under a condition that control parameters of a left block and an upper block are used, when the signal type is a first type; and the context is determined under a third condition that the control parameter of the upper block is not used and a hierarchical depth of a data unit to which the control parameter of the current block belongs is used, when the signal type is a third type, and the third type is one or more of (i) “merge_flag”, (ii) “ref_idx_l0” or “ref_idx_l1”, (iii) “inter_pred_flag”, (iv) “mvd_l0” or “mvd_l1”, (v) “intra_chroma_pred_mode”, (vi) “cbf_luma”, and (vii) “cbf_cb” or “cbf_cr”.

Abstract: Provided is an encoder including: circuitry; and memory coupled to the circuitry. In operation, the circuitry: performs a mapping process of Luma Mapping with Chroma Scaling (LMCS) for transforming a first pixel value space applied to a luma display image signal into a second pixel value space applied to a luma encoding process signal, using line segments forming a transform curve, each of which corresponds to a different one of sections obtained by partitioning the first pixel value space; and encodes an image, and in the performing of the LMCS, the circuitry determines the transform curve so that among boundary values in the second pixel value space, a first value obtained by dividing a boundary value by a base width defined according to a bit depth of the image is not equal to a second value obtained by dividing another boundary value by the base width.

Abstract: An image coding method comprising: obtaining current signals to be coded of each of the processing units of the image; generating a binary signal by performing binarization on each of the current signals to be coded; selecting a context for each of the current signals to be coded from among a plurality of contexts; performing arithmetic coding of the binary signal by using coded probability information associated with the context selected in the selecting; and updating the coded probability information based on the binary signal, wherein, in the selecting, the context for the current signal to be coded is selected, as a shared context, for a signal which is included in one of a plurality of processing units and has a size different from a size of the processing unit including the current signal to be coded.

Abstract: An encoder includes memory and circuitry which: (i) encodes an image block; (ii) when encoding the image block: binarizes coefficient information indicating coefficients of the image block; and controls whether to apply arithmetic encoding to a binary data string obtained by binarizing the coefficient information; and (iii) when binarizing the coefficient information: binarizes the coefficient information according to a first syntax structure when arithmetic encoding is applied to the data string and a predetermined condition is not satisfied; binarizes the coefficient information according to a second syntax structure when arithmetic encoding is applied to the data string and the predetermined condition is satisfied; binarizes the coefficient information according to the second syntax structure when no arithmetic encoding is applied to the data string; and subtracts 1 from a value of an initial non-zero coefficient when no arithmetic encoding is applied to the data string when encoding the image block.

Abstract: An encoder includes circuitry and memory. Using the memory, the circuitry performs a primary transform on a derived prediction error, performs a secondary transform on a result of the primary transform, quantizes a result of the secondary transform, and encodes a result of the quantization as data of an image. When a current block to be processed has a predetermined shape, the encoder performs the secondary transform using, among secondary transform basis candidates that are secondary bases usable in the secondary transform, only a secondary transform basis candidate having a size that is not largest size containable in the current block.

Abstract: An encoder is disclosed which includes circuitry and memory. Using the memory, the circuitry, in a first operating mode, derives first motion vectors for a first block obtained by splitting a picture, and generates a prediction image corresponding to the first block, with a bi-directional optical flow flag settable to true, and by referring to spatial gradients of luminance generated based on the first motion vectors. Using the memory, the circuitry, in a second operating mode, derives second motion vectors for a sub-block obtained by splitting a second block, the second block being obtained by splitting the picture, and generates a prediction image corresponding to the sub-block, with the bi-directional optical flow flag set to false.

Abstract: An encoder that; obtains two prediction images by performing motion compensation using two motion vectors; obtains a gradient value of each of pixels included in the two prediction images; derives a local motion estimation value for each of sub-blocks based on the pixel value and the gradient value of each of the pixels, the sub-blocks being obtained by partitioning the current block; and generates a final prediction image for the current block using the pixel value and the gradient value of each of the pixels, and the local motion estimation value derived for each of the sub-blocks. Each of the pixels in the two prediction images is interpolated with sub-pixel accuracy, and a reference range for the interpolation is included in a normal reference range that is referred to for motion compensation for the current block in normal inter prediction performed without using the local motion estimation value.

Abstract: An image coding method includes: deriving a candidate for a motion vector predictor from a co-located motion vector; adding the candidate to a list; selecting the motion vector predictor from the list; and coding a current block and coding a current motion vector, wherein the deriving includes: deriving the candidate by a first derivation scheme in the case of determining that each of a current reference picture and a co-located reference picture is a long-term reference picture; and deriving the candidate by a second derivation scheme in the case of determining that each of the current reference picture and the co-located reference picture is a short-term reference picture.