Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/169—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding
  • H04N19/17—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object
  • H04N19/176—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the coding unit, i.e. the structural portion or semantic portion of the video signal being the object or the subject of the adaptive coding the unit being an image region, e.g. an object the region being a block, e.g. a macroblock
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
  • H04N19/103—Selection of coding mode or of prediction mode
  • H04N19/105—Selection of the reference unit for prediction within a chosen coding or prediction mode, e.g. adaptive choice of position and number of pixels used for prediction
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
  • H04N19/103—Selection of coding mode or of prediction mode
  • H04N19/109—Selection of coding mode or of prediction mode among a plurality of temporal predictive coding modes
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
  • H04N19/119—Adaptive subdivision aspects, e.g. subdivision of a picture into rectangular or non-rectangular coding blocks
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/102—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or selection affected or controlled by the adaptive coding
  • H04N19/124—Quantisation
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/10—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding
  • H04N19/134—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using adaptive coding characterised by the element, parameter or criterion affecting or controlling the adaptive coding
  • H04N19/157—Assigned coding mode, i.e. the coding mode being predefined or preselected to be further used for selection of another element or parameter
  • H04N19/159—Prediction type, e.g. intra-frame, inter-frame or bidirectional frame prediction
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/44—Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/50—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding
  • H04N19/503—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using predictive coding involving temporal prediction
  • H04N19/51—Motion estimation or motion compensation
  • H04N19/513—Processing of motion vectors
  • H04N19/517—Processing of motion vectors by encoding
  • H04N19/52—Processing of motion vectors by encoding by predictive encoding
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/60—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding
  • H04N19/61—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding in combination with predictive coding
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/60—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding
  • H04N19/625—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using transform coding using discrete cosine transform [DCT]
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/70—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals characterised by syntax aspects related to video coding, e.g. related to compression standards
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/90—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using coding techniques not provided for in groups H04N19/10-H04N19/85, e.g. fractals
  • H04N19/91—Entropy coding, e.g. variable length coding [VLC] or arithmetic coding
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N19/00—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals
  • H04N19/90—Methods or arrangements for coding, decoding, compressing or decompressing digital video signals using coding techniques not provided for in groups H04N19/10-H04N19/85, e.g. fractals
  • H04N19/96—Tree coding, e.g. quad-tree coding

Definitions

• This patent document is directed generally to image and video coding and decoding technologies.
• Devices, systems and methods for complexity reduction of non-adjacent merge design are described.
• the presently disclosed technology discloses rules to select non-adjacent merge candidates to keep the size of the line buffer under a threshold.
• the described methods may be applied to both the existing video coding standards (e.g., High Efficiency Video Coding (HEVC)) and future video coding standards or video codecs.
• HEVC High Efficiency Video Coding
• the disclosed technology may be used to provide a method for video processing.
• This method includes receiving a current block of video data, selecting, based on a rule, a first non-adjacent block that is not adjacent to the current block, constructing a merge candidate list including a first merge candidate comprising motion information based on the first non-adjacent block, and processing the current block based on the merge candidate list.
• the above-described method is embodied in the form of processor-executable code and stored in a computer-readable program medium.
• the device may include a processor that is
• a video decoder apparatus may implement a method as described herein.
• FIG. 1 shows an example block diagram of a typical High Efficiency Video Coding (HE VC) video encoder and decoder.
• HE VC High Efficiency Video Coding
• FIG. 2 shows examples of macroblock (MB) partitions in H.264/AVC.
• FIG. 3 shows examples of splitting coding blocks (CBs) into prediction blocks (PBs).
• FIGS. 4A and 4B show an example of the subdivision of a coding tree block (CTB) into CBs and transform blocks (TBs), and the corresponding quadtree, respectively.
• CB coding tree block
• TBs transform blocks
• FIGS. 5 A and 5B show an example of the subdivisions and a corresponding QTBT
• FIGS. 6A-6E show examples of partitioning a coding block.
• FIG. 7 shows an example subdivision of a CB based on a QTBT.
• FIGS. 8A-8I show examples of the partitions of a CB supported the multi-tree type
• FIG. 9 shows an example of constructing a merge candidate list.
• FIG. 10 shows an example of positions of spatial candidates.
• FIG. 11 shows an example of candidate pairs subject to a redundancy check of spatial merge candidates.
• FIGS. 12A and 12B show examples of the position of a second prediction unit (PU) based on the size and shape of the current block.
• FIG. 13 shows an example of motion vector scaling for temporal merge candidates.
• FIG. 14 shows an example of candidate positions for temporal merge candidates.
• FIG. 15 shows an example of generating a combined bi-predictive merge candidate.
• FIG. 16 shows an example of constructing motion vector prediction candidates.
• FIG. 17 shows an example of motion vector scaling for spatial motion vector candidates.
• FIG. 18 shows an example of motion prediction using the alternative temporal motion vector prediction (ATMVP) algorithm for a coding unit (CU).
• ATMVP alternative temporal motion vector prediction
• FIG. 19 shows an example of the identification of a source block and source picture
• FIG. 20 shows an example of a coding unit (CU) with sub-blocks and neighboring blocks used by the spatial-temporal motion vector prediction (STMVP) algorithm.
• CU coding unit
• STMVP spatial-temporal motion vector prediction
• FIG. 21 shows an example of bilateral matching in pattern matched motion vector derivation (PMMVD) mode, which is a special merge mode based on the frame-rate up conversion (FRUC) algorithm.
• PMMVD pattern matched motion vector derivation
• FRUC frame-rate up conversion
• FIG. 22 shows an example of template matching in the FRUC algorithm.
• FIG. 23 shows an example of unilateral motion estimation in the FRUC algorithm.
• FIG. 24 shows an example of the decoder-side motion vector refinement (DMVR) algorithm based on bilateral template matching.
• FIG. 25 shows an example of spatial neighboring blocks used to derive the spatial merge candidates.
• FIG. 26 shows exemplary pseudocode for adding non-adjacent merge candidates.
• FIG. 27 shows an example of a restricted region for non-adjacent blocks.
• FIG. 28 shows a flowchart of an example method for video processing in accordance with the presently disclosed technology.
• FIG. 29 is a block diagram of an example of a hardware platform for implementing a visual media decoding or a visual media encoding technique described in the present document.
• Video codecs typically include an electronic circuit or software that compresses or decompresses digital video, and are continually being improved to provide higher coding efficiency.
• a video codec converts uncompressed video to a compressed format or vice versa.
• the compressed format usually conforms to a standard video compression specification, e.g., the High Efficiency Video Coding (HEVC) standard (also known as H.265 or MPEG-H Part 2), the Versatile Video Coding standard to be finalized, or other current and/or future video coding standards.
• HEVC High Efficiency Video Coding
• MPEG-H Part 2 the Versatile Video Coding standard to be finalized, or other current and/or future video coding standards.
• Embodiments of the disclosed technology may be applied to existing video coding standards (e.g., HEVC, H.265) and future standards to improve compression performance. Section headings are used in the present document to improve readability of the description and do not in any way limit the discussion or the embodiments (and/or implementations) to the respective sections only.
• FIG. 1 shows an example block diagram of a typical HEVC video encoder and decoder.
• An encoding algorithm producing an HEVC compliant bitstream would typically proceed as follows. Each picture is split into block-shaped regions, with the exact block partitioning being conveyed to the decoder. The first picture of a video sequence (and the first picture at each clean random access point into a video sequence) is coded using only intra picture prediction (that uses some prediction of data spatially from region-to-region within the same picture, but has no dependence on other pictures). For all remaining pictures of a sequence or between random access points, inter-picture temporally predictive coding modes are typically used for most blocks.
• the encoding process for inter-picture prediction consists of choosing motion data comprising the selected reference picture and motion vector (MV) to be applied for predicting the samples of each block.
• the encoder and decoder generate identical inter-picture prediction signals by applying motion compensation (MC) using the MV and mode decision data, which are transmitted as side information.
• MC motion compensation
• the residual signal of the intra- or inter-picture prediction which is the difference between the original block and its prediction, is transformed by a linear spatial transform.
• the transform coefficients are then scaled, quantized, entropy coded, and transmitted together with the prediction information.
• the encoder duplicates the decoder processing loop (see gray-shaded boxes in FIG. 1) such that both will generate identical predictions for subsequent data. Therefore, the quantized transform coefficients are constructed by inverse scaling and are then inverse transformed to duplicate the decoded approximation of the residual signal.
• the residual is then added to the prediction, and the result of that addition may then be fed into one or two loop filters to smooth out artifacts induced by block-wise processing and quantization.
• the final picture representation (that is a duplicate of the output of the decoder) is stored in a decoded picture buffer to be used for the prediction of subsequent pictures.
• the order of encoding or decoding processing of pictures often differs from the order in which they arrive from the source; necessitating a distinction between the decoding order (i.e., bitstream order) and the output order (i.e., display order) for a decoder.
• Video material to be encoded by HEVC is generally expected to be input as progressive scan imagery (either due to the source video originating in that format or resulting from deinterlacing prior to encoding).
• No explicit coding features are present in the HEVC design to support the use of interlaced scanning, as interlaced scanning is no longer used for displays and is becoming substantially less common for distribution.
• a metadata syntax has been provided in HEVC to allow an encoder to indicate that interlace-scanned video has been sent by coding each field (i.e., the even or odd numbered lines of each video frame) of interlaced video as a separate picture or that it has been sent by coding each interlaced frame as an HEVC coded picture. This provides an efficient method of coding interlaced video without burdening decoders with a need to support a special decoding process for it.
• the core of the coding layer in previous standards was the macroblock, containing a 16x 16 block of luma samples and, in the usual case of 4:2:0 color sampling, two corresponding 8x8 blocks of chroma samples.
• An intra-coded block uses spatial prediction to exploit spatial correlation among pixels. Two partitions are defined: 16x16 and 4x4.
• An inter-coded block uses temporal prediction, instead of spatial prediction, by estimating motion among pictures.
• Motion can be estimated independently for either 16x16 macroblock or any of its sub-macroblock partitions: 16x8, 8x16, 8x8, 8x4, 4x8, 4x4, as shown in FIG. 2. Only one motion vector (MV) per sub-macroblock partition is allowed.
• MV motion vector
• a coding tree unit (CTU) is split into coding units (CUs) by using a quadtree structure denoted as coding tree to adapt to various local characteristics.
• the decision whether to code a picture area using inter-picture (temporal) or intra-picture (spatial) prediction is made at the CU level.
• Each CU can be further split into one, two or four prediction units (PUs) according to the PU splitting type. Inside one PU, the same prediction process is applied and the relevant information is transmitted to the decoder on a PU basis.
• a CU After obtaining the residual block by applying the prediction process based on the PU splitting type, a CU can be partitioned into transform units (TUs) according to another quadtree structure similar to the coding tree for the CU.
• transform units transform units
• One of key feature of the HEVC structure is that it has the multiple partition conceptions including CU, PU, and TU.
• Certain features involved in hybrid video coding using HEVC include:
• ( 1 ) Coding tree units tCTUs) and coding tree block tCTB) structure The analogous structure in HEVC is the coding tree unit (CTU), which has a size selected by the encoder and can be larger than a traditional macroblock.
• the CTU consists of a luma CTB and the corresponding chroma CTBs and syntax elements.
• HEVC then supports a partitioning of the CTBs into smaller blocks using a tree structure and quadtree-like signaling.
• Coding units CUs
• CBsT Coding blocks
• the quadtree syntax of the CTU specifies the size and positions of its luma and chroma CBs.
• the root of the quadtree is associated with the CTU.
• the size of the luma CTB is the largest supported size for a luma CB.
• the splitting of a CTU into luma and chroma CBs is signaled jointly.
• a CTB may contain only one CU or may be split to form multiple CUs, and each CU has an associated partitioning into prediction units (PUs) and a tree of transform units (TUs).
• PUs prediction units
• TUs tree of transform units
• Prediction units and prediction blocks tPBs The decision whether to code a picture area using inter picture or intra picture prediction is made at the CU level.
• a PU partitioning structure has its root at the CU level.
• the luma and chroma CBs can then be further split in size and predicted from luma and chroma prediction blocks (PBs).
• PBs luma and chroma prediction blocks
• HEVC supports variable PB sizes from 64x64 down to 4x4 samples.
• FIG. 3 shows examples of allowed PBs for an MxM CU.
• the prediction residual is coded using block transforms.
• a TU tree structure has its root at the CU level.
• the luma CB residual may be identical to the luma transform block (TB) or may be further split into smaller luma TBs. The same applies to the chroma TBs.
• Integer basis functions similar to those of a discrete cosine transform (DCT) are defined for the square TB sizes 4x4, 8x8, 16x16, and 32x32.
• DCT discrete cosine transform
• an integer transform derived from a form of discrete sine transform (DST) is alternatively specified.
• a CB can be recursively partitioned into transform blocks (TBs).
• the partitioning is signaled by a residual quadtree. Only square CB and TB partitioning is specified, where a block can be recursively split into quadrants, as illustrated in FIGS. 4A and 4B.
• a flag signals whether it is split into four blocks of size M/2xM/2. If further splitting is possible, as signaled by a maximum depth of the residual quadtree indicated in the sequence parameter set (SPS), each quadrant is assigned a flag that indicates whether it is split into four quadrants.
• SPS sequence parameter set
• the leaf node blocks resulting from the residual quadtree are the transform blocks that are further processed by transform coding.
• the encoder indicates the maximum and minimum luma TB sizes that it will use. Splitting is implicit when the CB size is larger than the maximum TB size. Not splitting is implicit when splitting would result in a luma TB size smaller than the indicated minimum.
• the chroma TB size is half the luma TB size in each dimension, except when the luma TB size is 4x4, in which case a single 4x4 chroma TB is used for the region covered by four 4x4 luma TBs.
• intra-picture- predicted CUs the decoded samples of the nearest-neighboring TBs (within or outside the CB) are used as reference data for intra picture prediction.
• the HEVC design allows a TB to span across multiple PBs for inter-picture predicted CUs to maximize the potential coding efficiency benefits of the quadtree-structured TB partitioning.
• a CTB is divided according to a quad-tree structure, the nodes of which are coding units.
• the plurality of nodes in a quad-tree structure includes leaf nodes and non-leaf nodes.
• the leaf nodes have no child nodes in the tree structure (i.e., the leaf nodes are not further split).
• The, non-leaf nodes include a root node of the tree structure.
• the root node corresponds to an initial video block of the video data (e.g., a CTB).
• the respective non-root node corresponds to a video block that is a sub-block of a video block corresponding to a parent node in the tree structure of the respective non-root node.
• Each respective non-leaf node of the plurality of non-leaf nodes has one or more child nodes in the tree structure.
• JEM Joint Exploration Model
• QTBT quadtree plus binary tree
• TT ternary tree
• the QTBT structure removes the concepts of multiple partition types, i.e. it removes the separation of the CU, PU and TU concepts, and supports more flexibility for CU partition shapes.
• a CU can have either a square or rectangular shape.
• a coding tree unit (CTU) is first partitioned by a quadtree structure.
• the quadtree leaf nodes are further partitioned by a binary tree structure.
• the binary tree leaf nodes are called coding units (CUs), and that segmentation is used for prediction and transform processing without any further partitioning.
• a CU sometimes consists of coding blocks (CBs) of different colour components, e.g. one CU contains one luma CB and two chroma CBs in the case of P and B slices of the 4:2:0 chroma format and sometimes consists of a CB of a single component, e.g., one CU contains only one luma CB or just two chroma CBs in the case of I slices.
• CBs coding blocks
• CTU size the root node size of a quadtree, the same concept as in HEVC
• MinQTSize the minimally allowed quadtree leaf node size
• MaxBTSize the maximally allowed binary tree root node size
• MaxBTDepth the maximally allowed binary tree depth
• MinBTSize the minimally allowed binary tree leaf node size
• the CTU size is set as 128x 128 luma samples with two corresponding 64x64 blocks of chroma samples, th eMinQTSize is set as 16x 16, th e MaxBTSize is set as 64x64, th e MinBTSize (for both width and height) is set as 4x4, and the MaxBTDepth is set as 4.
• the quadtree partitioning is applied to the CTU first to generate quadtree leaf nodes.
• the quadtree leaf nodes may have a size from 16x 16 (i.e., th eMinQTSize) to 128x128 (i.e., the CTU size).
• the quadtree leaf node is also the root node for the binary tree and it has the binary tree depth as 0.
• MaxBTDepth i.e., 4
• no further splitting is considered.
• MinBTSize i.e. 4
• no further horizontal splitting is considered.
• the binary tree node has height equal to MinBTSize
• no further vertical splitting is considered.
• the leaf nodes of the binary tree are further processed by prediction and transform processing without any further partitioning. In the JEM, the maximum CTU size is 256x256 luma samples.
• FIG. 5A shows an example of block partitioning by using QTBT
• FIG. 5B shows the corresponding tree representation.
• the solid lines indicate quadtree splitting and dotted lines indicate binary tree splitting.
• each splitting (i.e., non-leaf) node of the binary tree one flag is signalled to indicate which splitting type (i.e., horizontal or vertical) is used, where 0 indicates horizontal splitting and 1 indicates vertical splitting.
• the quadtree splitting there is no need to indicate the splitting type since quadtree splitting always splits a block both horizontally and vertically to produce 4 sub-blocks with an equal size.
• the QTBT scheme supports the ability for the luma and chroma to have a separate QTBT structure.
• the luma and chroma CTBs in one CTU share the same QTBT structure.
• the luma CTB is partitioned into CUs by a QTBT structure
• the chroma CTBs are partitioned into chroma CUs by another QTBT structure. This means that a CU in an I slice consists of a coding block of the luma component or coding blocks of two chroma components, and a CU in a P or B slice consists of coding blocks of all three colour components.
• inter prediction for small blocks is restricted to reduce the memory access of motion compensation, such that bi-prediction is not supported for 4x8 and 8x4 blocks, and inter prediction is not supported for 4x4 blocks. In the QTBT of the JEM, these restrictions are removed.
• FIG. 6A shows an example of quad-tree (QT) partitioning
• FIGS. 6B and 6C show examples of the vertical and horizontal binary-tree (BT) partitioning, respectively.
• BT binary-tree
• ternary tree (TT) partitions e.g., horizontal and vertical center-side ternary- trees (as shown in FIGS. 6D and 6E) are supported.
• region tree quad-tree
• prediction tree binary-tree or ternary-tree
• a CTU is firstly partitioned by region tree (RT).
• a RT leaf may be further split with prediction tree (PT).
• PT leaf may also be further split with PT until max PT depth is reached.
• a PT leaf is the basic coding unit. It is still called CU for convenience.
• a CU cannot be further split.
• Prediction and transform are both applied on CU in the same way as JEM.
• the whole partition structure is named‘multiple-type-tree’.
• a tree structure called a Multi-Tree Type which is a generalization of the QTBT, is supported.
• MTT Multi-Tree Type
• FIG. 7 a Coding Tree Unit (CTU) is firstly partitioned by a quad-tree structure.
• the quad-tree leaf nodes are further partitioned by a binary-tree structure.
• the structure of the MTT constitutes of two types of tree nodes: Region Tree (RT) and Prediction Tree (PT), supporting nine types of partitions, as shown in FIGS. 8A-8I.
• a region tree can recursively split a CTU into square blocks down to a 4x4 size region tree leaf node.
• a prediction tree can be formed from one of three tree types: Binary Tree, Ternary Tree, and Asymmetric Binary Tree.
• a PT split it is prohibited to have a quadtree partition in branches of the prediction tree.
• JEM the luma tree and the chroma tree are separated in I slices.
• Video coding standards have significantly improved over the years, and now provide, in part, high coding efficiency and support for higher resolutions.
• Recent standards such as HEVC and H.265 are based on the hybrid video coding structure wherein temporal prediction plus transform coding are utilized.
• Each inter-predicted PU has motion parameters for one or two reference picture lists.
• motion parameters include a motion vector and a reference picture index.
• the usage of one of the two reference picture lists may also be signaled using inter _predjdc.
• motion vectors may be explicitly coded as deltas relative to predictors.
• a merge mode is specified whereby the motion parameters for the current PU are obtained from neighboring PUs, including spatial and temporal candidates.
• the merge mode can be applied to any inter-predicted PU, not only for skip mode.
• the alternative to merge mode is the explicit transmission of motion parameters, where motion vector, corresponding reference picture index for each reference picture list and reference picture list usage are signaled explicitly per each PU.
• the PU is produced from one block of samples. This is referred to as‘uni-prediction’. Uni-prediction is available both for P-slices and B-slices.
• the PU is produced from two blocks of samples. This is referred to as‘bi-prediction’. Bi-prediction is available for B-slices only.
• Step 1 Initial candidates derivation
• Step 1.1 Spatial candidates derivation
• Step 1.2 Redundancy check for spatial candidates
• Step 1.3 Temporal candidates derivation
• Step 2 Additional candidates insertion
• Step 2.1 Creation of bi-predictive candidates
• Step 2.2 Insertion of zero motion candidates
• FIG. 9 shows an example of constructing a merge candidate list based on the sequence of steps summarized above.
• For spatial merge candidate derivation a maximum of four merge candidates are selected among candidates that are located in five different positions.
• temporal merge candidate derivation a maximum of one merge candidate is selected among two candidates. Since constant number of candidates for each PU is assumed at decoder, additional candidates are generated when the number of candidates does not reach to maximum number of merge candidate (MaxNumMergeCand) which is signalled in slice header. Since the number of candidates is constant, index of best merge candidate is encoded using truncated unary binarization (TU). If the size of CU is equal to 8, all the PUs of the current CU share a single merge candidate list, which is identical to the merge candidate list of the 2Nx2N prediction unit.
• TU truncated unary binarization
• FIG. 13 shows an example of the derivation of the scaled motion vector for a temporal merge candidate (as the dotted line), which is scaled from the motion vector of the co located PU using the POC distances, tb and td, where tb is defined to be the POC difference between the reference picture of the current picture and the current picture and td is defined to be the POC difference between the reference picture of the co-located picture and the co-located picture.
• the reference picture index of temporal merge candidate is set equal to zero.
• two motion vectors one is for reference picture list 0 and the other is for reference picture list 1 , are obtained and combined to make the bi-predictive merge candidate.
• the position for the temporal candidate is selected between candidates Co and Ci, as depicted in FIG. 14. If PU at position Co is not available, is intra coded, or is outside of the current CTU, position Ci is used. Otherwise, position Co is used in the derivation of the temporal merge candidate.
• merge candidates there are two additional types of merge candidates: combined bi-predictive merge candidate and zero merge candidate.
• Combined bi- predictive merge candidates are generated by utilizing spatio-temporal merge candidates.
• Combined bi-predictive merge candidate is used for B-Slice only.
• the combined bi-predictive candidates are generated by combining the first reference picture list motion parameters of an initial candidate with the second reference picture list motion parameters of another. If these two tuples provide different motion hypotheses, they will form a new bi-predictive candidate.
• FIG. 15 shows an example of this process, wherein two candidates in the original list (710, on the left), which have mvLO and refldxLO or mvLl and refldxLl, are used to create a combined bi-predictive merge candidate added to the final list (720, on the right).
• Zero motion candidates are inserted to fill the remaining entries in the merge candidates list and therefore hit the MaxNumMergeCand capacity. These candidates have zero spatial displacement and a reference picture index which starts from zero and increases every time a new zero motion candidate is added to the list. The number of reference frames used by these candidates is one and two for uni- and bi-directional prediction, respectively. In some embodiments, no redundancy check is performed on these candidates.
• motion estimation can be performed in parallel whereby the motion vectors for all prediction units inside a given region are derived simultaneously.
• the derivation of merge candidates from spatial neighborhood may interfere with parallel processing as one prediction unit cannot derive the motion parameters from an adjacent PU until its associated motion estimation is completed.
• a motion estimation region may be defined.
• the size of the MER may be signaled in the picture parameter set (PPS) using the “log2_parallel_merge_level_minus2” syntax element.
• log2_parallel_merge_level_minus2 plus 2 specifies the value of the variable Log2ParMrgLevel, which is used in the derivation process for luma motion vectors for merge mode and the derivation process for spatial merging candidates as specified in an existing video coding standard.
• the value of log2_parallel_merge_level_minus2 shall be in the range of 0 to CtbLog2SizeY - 2, inclusive.
• Log2ParMrgLevel is derived as follows:
• Log2ParMrgLevel log2_parallel_merge_level_minus2 + 2
• Log2ParMrgLevel indicates the built-in capability of parallel derivation of the merging candidate lists. For example, when Log2ParMrgLevel is equal to 6, the merging candidate lists for all the prediction units (PUs) and coding units (CUs) contained in a 64x64 block can be derived in parallel.
• Table 1 General picture parameter set RBSP syntax
• Motion vector prediction exploits spatio-temporal correlation of motion vector with neighboring PUs, which is used for explicit transmission of motion parameters. It constructs a motion vector candidate list by firstly checking availability of left, above temporally neighboring PU positions, removing redundant candidates and adding zero vector to make the candidate list to be constant length. Then, the encoder can select the best predictor from the candidate list and transmit the corresponding index indicating the chosen candidate. Similarly with merge index signaling, the index of the best motion vector candidate is encoded using truncated unary.
• FIG. 16 summarizes derivation process for motion vector prediction candidate, and may be implemented for each reference picture list with refidx as an input.
• motion vector candidate two types are considered: spatial motion vector candidate and temporal motion vector candidate.
• spatial motion vector candidate derivation two motion vector candidates are eventually derived based on motion vectors of each PU located in five different positions as previously shown in FIG. 10.
• one motion vector candidate is selected from two candidates, which are derived based on two different co-located positions. After the first list of spatio-temporal candidates is made, duplicated motion vector candidates in the list are removed. If the number of potential candidates is larger than two, motion vector candidates whose reference picture index within the associated reference picture list is larger than 1 are removed from the list. If the number of spatio-temporal motion vector candidates is smaller than two, additional zero motion vector candidates is added to the list.
• the no-spatial-scaling cases are checked first followed by the cases that allow spatial scaling. Spatial scaling is considered when the POC is different between the reference picture of the neighbouring PU and that of the current PU regardless of reference picture list. If all PUs of left candidates are not available or are intra coded, scaling for the above motion vector is allowed to help parallel derivation of left and above MV candidates. Otherwise, spatial scaling is not allowed for the above motion vector.
• the motion vector of the neighbouring PU is scaled in a similar manner as for temporal scaling.
• One difference is that the reference picture list and index of current PU is given as input; the actual scaling process is the same as that of temporal scaling.
• the reference picture index is signaled to the decoder.
• bitstream For the AMVP mode, four parts may be signalled in the bitstream, e.g., prediction direction, reference index, MVD and mv predictor candidate index, which are described in the context of the syntax shown in Table 2 and Table 3.
• JEM Joint Exploration Model
• JEM Joint Exploration Model
• affine prediction alternative temporal motion vector prediction
• STMVP spatial-temporal motion vector prediction
• BIO bi directional optical flow
• FRUC Frame-Rate Up Conversion
• LAMVR Locally Adaptive Motion Vector Resolution
• OBMC Overlapped Block Motion Compensation
• LIC Local Illumination Compensation
• DMVR Decoder-side Motion Vector Refinement
• each CU can have at most one set of motion parameters for each prediction direction.
• two sub-CU level motion vector prediction methods are considered in the encoder by splitting a large CU into sub- CUs and deriving motion information for all the sub-CUs of the large CU.
• Alternative temporal motion vector prediction (ATMVP) method allows each CU to fetch multiple sets of motion information from multiple blocks smaller than the current CU in the collocated reference picture.
• STMVP spatial-temporal motion vector prediction
• motion vectors of the sub-CUs are derived recursively by using the temporal motion vector predictor and spatial neighbouring motion vector.
• the motion compression for the reference frames may be disabled.
• the temporal motion vector prediction (TMVP) method is modified by fetching multiple sets of motion information (including motion vectors and reference indices) from blocks smaller than the current CU.
• FIG. 18 shows an example of ATMVP motion prediction process for a CU 1800.
• the ATMVP method predicts the motion vectors of the sub-CUs 1801 within a CU 1800 in two steps.
• the first step is to identify the corresponding block 1851 in a reference picture 1850 with a temporal vector.
• the reference picture 1850 is also referred to as the motion source picture.
• the second step is to split the current CU 1800 into sub-CUs 1801 and obtain the motion vectors as well as the reference indices of each sub-CU from the block corresponding to each sub-CU.
• a reference picture 1850 and the corresponding block is determined by the motion information of the spatial neighboring blocks of the current CU 1800.
• the first merge candidate in the merge candidate list of the current CU 1800 is used.
• the first available motion vector as well as its associated reference index are set to be the temporal vector and the index to the motion source picture. This way, the corresponding block may be more accurately identified, compared with TMVP, wherein the corresponding block (sometimes called collocated block) is always in a bottom-right or center position relative to the current CU.
• the first merge candidate is from the left neighboring block (i.e., the left neighboring block).
• the associated MV and reference picture are utilized to identify the source block and source picture.
• a corresponding block of the sub-CU 1851 is identified by the temporal vector in the motion source picture 1850, by adding to the coordinate of the current CU the temporal vector.
• the motion information of its corresponding block e.g., the smallest motion grid that covers the center sample
• the motion information of a corresponding NxN block is identified, it is converted to the motion vectors and reference indices of the current sub-CU, in the same way as TMVP of HEVC, wherein motion scaling and other procedures apply.
• the decoder checks whether the low-delay condition (e.g.
• motion vector MVx e.g., the motion vector corresponding to reference picture list X
• motion vector MVy e.g., with X being equal to 0 or 1 and Y being equal to l-X
• FIG. 20 shows an example of one CU with four sub-blocks and neighboring blocks.
• 8x8 CU 2000 that includes four 4x4 sub-CUs A (2001), B (2002), C (2003), and D (2004).
• the neighboring 4x4 blocks in the current frame are labelled as a (2011), b (2012), c (2013), and d (2014).
• the motion derivation for sub-CU A starts by identifying its two spatial neighbors.
• the first neighbor is the NxN block above sub-CU A 1101 (block c 2013). If this block c (2013) is not available or is intra coded the other NxN blocks above sub-CU A (2001) are checked (from left to right, starting at block c 2013).
• the second neighbor is a block to the left of the sub- CU A 2001 (block b 2012). If block b (2012) is not available or is intra coded other blocks to the left of sub-CU A 2001 are checked (from top to bottom, staring at block b 2012).
• the motion information obtained from the neighboring blocks for each list is scaled to the first reference frame for a given list.
• temporal motion vector predictor (TMVP) of sub-block A 2001 is derived by following the same procedure of TMVP derivation as specified in HEVC.
• the motion information of the collocated block at block D 2004 is fetched and scaled accordingly.
• all available motion vectors are averaged separately for each reference list. The averaged motion vector is assigned as the motion vector of the current sub-CU.
• the sub-CU modes are enabled as additional merge candidates and there is no additional syntax element required to signal the modes.
• Two additional merge candidates are added to merge candidates list of each CU to represent the ATMVP mode and STMVP mode. In other embodiments, up to seven merge candidates may be used, if the sequence parameter set indicates that ATMVP and STMVP are enabled.
• the encoding logic of the additional merge candidates is the same as for the merge candidates in the HM, which means, for each CU in P or B slice, two more RD checks may be needed for the two additional merge candidates.
• all bins of the merge index are context coded by CABAC (Context-based Adaptive Binary Arithmetic Coding). In other embodiments, e.g., HEVC, only the first bin is context coded and the remaining bins are context by-pass coded.
• CABAC Context-based Adaptive Binary Arithmetic Coding
• motion vector differences (between the motion vector and predicted motion vector of a PU) are signalled in units of quarter luma samples when use integer mv flag is equal to 0 in the slice header.
• MVDs motion vector differences
• LAMVR locally adaptive motion vector resolution
• MVD can be coded in units of quarter luma samples, integer luma samples or four luma samples.
• the MVD resolution is controlled at the coding unit (CU) level, and MVD resolution flags are conditionally signalled for each CU that has at least one non-zero MVD components.
• a first flag is signalled to indicate whether quarter luma sample MV precision is used in the CU.
• the first flag (equal to 1) indicates that quarter luma sample MV precision is not used, another flag is signalled to indicate whether integer luma sample MV precision or four luma sample MV precision is used.
• the quarter luma sample MV resolution is used for the CU.
• the MVPs in the AMVP candidate list for the CU are rounded to the corresponding precision.
• CU-level RD checks are used to determine which MVD resolution is to be used for a CU. That is, the CU-level RD check is performed three times for each MVD resolution.
• the following encoding schemes are applied in the JEM:
• the motion information of the current CU (integer luma sample accuracy) is stored.
• the stored motion information (after rounding) is used as the starting point for further small range motion vector refinement during the RD check for the same CU with integer luma sample and 4 luma sample MVD resolution so that the time-consuming motion estimation process is not duplicated three times.
• [00130] RD check of a CU with 4 luma sample MVD resolution is conditionally invoked. For a CU, when RD cost integer luma sample MVD resolution is much larger than that of quarter luma sample MVD resolution, the RD check of 4 luma sample MVD resolution for the CU is skipped.
• PMMVD pattern matched motion vector derivation
• FRUC Frame-Rate Up Conversion
• a FRUC flag can be signaled for a CU when its merge flag is true.
• a merge index can be signaled and the regular merge mode is used.
• an additional FRUC mode flag can be signaled to indicate which method (e.g., bilateral matching or template matching) is to be used to derive motion information for the block.
• the decision on whether using FRUC merge mode for a CU is based on RD cost selection as done for normal merge candidate. For example, multiple matching modes (e.g., bilateral matching and template matching) are checked for a CU by using RD cost selection. The one leading to the minimal cost is further compared to other CU modes. If a FRUC matching mode is the most efficient one, FRUC flag is set to true for the CU and the related matching mode is used.
• multiple matching modes e.g., bilateral matching and template matching
• motion derivation process in FRUC merge mode has two steps: a CU-level motion search is first performed, then followed by a Sub-CU level motion refinement.
• CU level an initial motion vector is derived for the whole CU based on bilateral matching or template matching.
• a list of MV candidates is generated and the candidate that leads to the minimum matching cost is selected as the starting point for further CU level refinement.
• a local search based on bilateral matching or template matching around the starting point is performed.
• the MV results in the minimum matching cost is taken as the MV for the whole CU.
• the motion information is further refined at sub-CU level with the derived CU motion vectors as the starting points.
• the following derivation process is performed for a W X H CU motion information derivation.
• MV for the whole W x H CU is derived.
• the CU is further split into M x M sub-CUs.
• the value of M is calculated as in Eq. (3), D is a predefined splitting depth which is set to 3 by default in the JEM.
• the MV for each sub- CU is derived.
• FIG. 21 shows an example of bilateral matching used in the Frame-Rate Up
• the bilateral matching is used to derive motion information of the current CU by finding the closest match between two blocks along the motion trajectory of the current CU (2100) in two different reference pictures (2110, 2111).
• the motion vectors MV0 (2101) and MV1 (2102) pointing to the two reference blocks are proportional to the temporal distances, e.g., TD0 (2103) and TD1 (2104), between the current picture and the two reference pictures.
• the bilateral matching becomes mirror based bi-directional MV.
• FIG. 22 shows an example of template matching used in the Frame-Rate Up
• Template matching can be used to derive motion information of the current CU 2200 by finding the closest match between a template (e.g., top and/or left neighboring blocks of the current CU) in the current picture and a block (e.g., same size to the template) in a reference picture 2210. Except the aforementioned FRUC merge mode, the template matching can also be applied to AMVP mode. In both JEM and HEVC, AMVP has two candidates. With the template matching method, a new candidate can be derived. If the newly derived candidate by template matching is different to the first existing AMVP candidate, it is inserted at the very beginning of the AMVP candidate list and then the list size is set to two (e.g., by removing the second existing AMVP candidate). When applied to AMVP mode, only CU level search is applied.
• the MV candidate set at CU level can include the following: (1) original AMVP candidates if the current CU is in AMVP mode, (2) all merge candidates, (3) several MVs in the interpolated MV field (described later), and top and left neighboring motion vectors.
• each valid MV of a merge candidate can be used as an input to generate a MV pair with the assumption of bilateral matching.
• one valid MV of a merge candidate is (MVa, ref a ) at reference list A.
• the reference picture reft of its paired bilateral MV is found in the other reference list B so that reft and reft are temporally at different sides of the current picture. If such a reft is not available in reference list B, reft is determined as a reference which is different from reft and its temporal distance to the current picture is the minimal one in list B.
• MVb is derived by scaling MVa based on the temporal distance between the current picture and reft, reft.
• four MVs from the interpolated MV field can also be added to the CU level candidate list. More specifically, the interpolated MVs at the position (0, 0), (W/2, 0), (0, H/2) and (W/2, H/2) of the current CU are added.
• the original AMVP candidates are also added to CU level MV candidate set.
• 15 MVs for AMVP CUs and 13 MVs for merge CUs can be added to the candidate list.
• the MV candidate set at sub-CU level includes an MV determined from a CU-level search, (2) top, left, top-left and top-right neighboring MVs, (3) scaled versions of collocated MVs from reference pictures, (4) one or more ATMVP candidates (e.g., up to four), and (5) one or more STMVP candidates (e.g., up to four).
• the scaled MVs from reference pictures are derived as follows. The reference pictures in both lists are traversed. The MVs at a collocated position of the sub-CU in a reference picture are scaled to the reference of the starting CU-level MV.
• ATMVP and STMVP candidates can be the four first ones.
• one or more MVs are added to the candidate list.
• interpolated motion field Before coding a frame, interpolated motion field is generated for the whole picture based on unilateral ME. Then the motion field may be used later as CU level or sub-CU level MV candidates.
• FIG. 23 shows an example of unilateral Motion Estimation (ME) 2300 in the FRUC method.
• ME Motion Estimation
• the motion of the reference block is scaled to the current picture according to the temporal distance TD0 and TD1 (the same way as that of MV scaling of TMVP in HEVC) and the scaled motion is assigned to the block in the current frame. If no scaled MV is assigned to a 4x4 block, the block’s motion is marked as unavailable in the interpolated motion field.
• the matching cost is a bit different at different steps.
• the matching cost can be the absolute sum difference (S D) of bilateral matching or template matching.
• S D the absolute sum difference
• the matching cost C of bilateral matching at sub-CU level search is calculated as follows:
• w is a weighting factor. In some embodiments, w can be empirically set to 4.
• MV and MV S indicate the current MV and the starting MV, respectively.
• SAD may still be used as the matching cost of template matching at sub-CU level search.
• MV is derived by using luma samples only. The derived motion will be used for both luma and chroma for MC inter prediction. After MV is decided, final MC is performed using 8-taps interpolation filter for luma and 4-taps interpolation filter for chroma.
• MV refinement is a pattern based MV search with the criterion of bilateral matching cost or template matching cost.
• two search patterns are supported - an unrestricted center-biased diamond search (UCBDS) and an adaptive cross search for MV refinement at the CU level and sub-CU level, respectively.
• UMBDS center-biased diamond search
• the MV is directly searched at quarter luma sample MV accuracy, and this is followed by one-eighth luma sample MV refinement.
• the search range of MV refinement for the CU and sub-CU step are set equal to 8 luma samples.
• bi-prediction is applied because the motion information of a CU is derived based on the closest match between two blocks along the motion trajectory of the current CU in two different reference pictures.
• the encoder can choose among uni-prediction from listO, uni-prediction from listl, or bi prediction for a CU. The selection ca be based on a template matching cost as follows:
• costBi ⁇ factor * min (costO, costl)
• costO is the S D of listO template matching
• costl is the S D of listl template matching
• costBi is the SAD of bi-prediction template matching.
• the value of factor is equal to 1.25, it means that the selection process is biased toward bi-prediction.
• the inter prediction direction selection can be applied to the CU-level template matching process.
• a bi-prediction operation for the prediction of one block region, two prediction blocks, formed using a motion vector (MV) of listO and a MV of listl, respectively, are combined to form a single prediction signal.
• the two motion vectors of the bi-prediction are further refined by a bilateral template matching process.
• the bilateral template matching applied in the decoder to perform a distortion-based search between a bilateral template and the reconstruction samples in the reference pictures in order to obtain a refined MV without transmission of additional motion information.
• a bilateral template is generated as the weighted combination (i.e.
• the template matching operation consists of calculating cost measures between the generated template and the sample region (around the initial prediction block) in the reference picture. For each of the two reference pictures, the MV that yields the minimum template cost is considered as the updated MV of that list to replace the original one.
• the nine MV candidates are searched for each list.
• the nine MV candidates include the original MV and 8 surrounding MVs with one luma sample offset to the original MV in either the horizontal or vertical direction, or both.
• the two new MVs i.e., MV0' and MVT as shown in FIG. 24, are used for generating the final bi-prediction results.
• a sum of absolute differences (SAD) is used as the cost measure.
• DMVR is applied for the merge mode of bi-prediction with one MV from a reference picture in the past and another from a reference picture in the future, without the transmission of additional syntax elements.
• JEM when LIC, affine motion, FRUC, or sub-CU merge candidate is enabled for a CU, DMVR is not applied.
• a merge candidate list is first constructed by inserting the motion vectors and reference indices of the spatial neighboring and temporal neighboring blocks into the candidate list with redundancy checking until the number of the available candidates reaches the maximum candidate size of 19.
• the merge candidate list for the merge/skip mode is constructed by inserting spatial candidates, temporal candidates, affine candidates, advanced temporal MVP (ATMVP) candidate, spatial temporal MVP (STMVP) candidate and the additional candidates as used in HEVC (Combined candidates and Zero candidates) according to a pre-defined insertion order, and in the context of the numbered blocks shown in FIG. 25:
• IC flags are also inherited from merge candidates except for STMVP and affine. Moreover, for the first four spatial candidates, the bi-prediction ones are inserted before the ones with uni-prediction.
• Non-adjacent merge candidates may be added to the merge candidate list if the total number of available merge candidates hasn’t reached the maximumly allowed merge candidates.
• non-adjacent merge candidates may be inserted to the merge candidate list after the TMVP merge candidate. The process of adding non-adjacent merge candidates could be performed by the pseudocode shown in FIG. 26.
• prediction from motion information of non-adjacent blocks located above CTU rows may significantly increase the line buffer size.
• prediction from motion information of non-adjacent blocks could bring additional coding gain with the cost of storing all the motion information (typically on 4x4 level) into cache which significantly increase the complexity for hardware implementation.
• Embodiments of the presently disclosed technology overcome the drawbacks of existing implementations, thereby providing video coding with lower memory and complexity requirements and higher coding efficiencies.
• the selection of non-adjacent merge candidates based on the disclosed technology, which may enhance both existing and future video coding standards, is elucidated in the following examples described for various implementations.
• the examples of the disclosed technology provided below explain general concepts, and are not meant to be interpreted as limiting. In an example, unless explicitly indicated to the contrary, the various features described in these examples may be combined.
• Embodiments of the disclosed technology reduce the cache/line buffer size required by the non-adjacent merge candidate as well as methods for further improving the coding performance of non-adjacent merge candidates.
• the top-left sample coordinate of the current block be (Cx, Cy) and the coordinate of the top-left sample in one non-adjacent block by (NAx, NAy), with the origin (0,0) to be the top-left point of a picture/slice/tile/LCU row/LCU.
• the coordinate difference i.e., offset from the current block
• offsetX Cx-NAx
• offsetY Cy - NAy.
• Example 1 advantageously provides, at least, memory and buffer reductions.
• Example 1 In one example, only non-adjacent blocks located at certain positions are accessed when constructing merge candidates.
• (c) Alternatively, if the top-left sample in one non-adjacent block doesn’t satisfy the given conditions, the position of this block may be shifted, truncated or rounded to make sure the conditions are satisfied. For example, (NAx, NAy) may be modified to ( (NAx/M)*M, (NAy/N)*N) wherein 7’ is the integer division.
• the restricted region size covering all the non-adjacent blocks may be pre defined/signaled.
• a non-adjacent block calculated by a given offset (OffsetX, OffsetY) is outside the region, it is marked as unavailable or treated as intra-code mode.
• the corresponding motion information could be added a candidate to the candidate list. An example is depicted in FIG. 27.
• the region size is defined as one or more CTBs.
• NAx > ((Cx/W)*W)
• NAx ⁇ ((Cx/W)*W)+W.
• One or multiple thresholds may be predefined. They could be further dependent on minimum size of CU height/ minimum size of width/LCU size etc., al. For example, (LY-NAy) should be less than the minimum size of CU height, or (LY-NAy) should be less than twice of the minimum size of CU height.
• the region size or the threshold(s) may be signaled in a Sequence
• SPS Session Parameter Set
• PPS Picture Parameter Set
• VPS Video Parameter Set
• slice header a tile header, and so on.
• Example 2 advantageously provides, at least, reduction in computational complexity.
• Example 2 When inserting a new non-adjacent merge candidate, pruning may be applied to partial of available merge candidates.
• the new non-adjacent merge candidate is not pruned to other inserted non-adjacent merge candidates.
• the new non-adjacent merge candidate is not pruned to the temporal merge candidate, such as TMVP or ATMVP.
• the new non-adjacent merge candidate is pruned with some merge candidates from some specific neighboring blocks, but not pruned with some other merge candidates from some other specific neighboring blocks.
• method 2800 may be implemented at a video decoder and/or video encoder.
• FIG. 28 shows a flowchart of an exemplary method for video coding, which may be implemented in a video encoder.
• the method 2800 includes, at step 2810, receiving a current block of video data.
• the method 2800 includes, at step 2820, selecting, based on a rule, a first non- adjacent block that is not adjacent to the current block.
• the first non- adjacent block is selected from a plurality of non-adjacent blocks, and wherein a restricted region comprises each of the plurality of non-adjacent blocks.
• the restricted region corresponds to one or more coding tree blocks (CTBs) next to the current block.
• CTBs coding tree blocks
• a top-left sample coordinate of a picture segment is (0,0), wherein a top-left sample coordinate of the first non-adjacent block is (NAx,NAy).
• the rule specifies that (NAx, NAy) can be modified to ( ( NAx / M ) x M ) and ( ( NAx / N ) x N ), where / denotes integer division.
• a top-left sample of a largest coding unit (LCU) covering the current block is (Lx,Ly), and at least one of (Lx-NAx), abs(Lx-NAx), (Ly-NAy) and abs(Ly- NAy) are less than predetermined thresholds, where abs() denotes the absolute value function.
• the method 2800 includes, at step 2830, constructing a merge candidate list including a first merge candidate comprising motion information based on the first non-adjacent block.
• the method 2800 further includes inserting the first merge candidate into a merge candidate list, and as described in the context of Example 3, may be pruned or not pruned to specific types of merge candidates.
• the first merge candidate is not pruned to other merge candidates constructed from other non-adjacent blocks in the merge candidate list.
• first merge candidate is not pruned to temporal merge candidates in the merge candidate list.
• the first merge candidate is pruned to other candidates from a first set of neighboring blocks, and the first merge candidate is not pruned to candidates from a second set of neighboring blocks that is different from the first set of neighboring blocks.
• the first non- adjacent block may or may not be restricted to certain types of coding.
• the first non-adjacent block is an advanced motion vector prediction (AMVP)-coded non-adjacent block.
• AMVP advanced motion vector prediction
• the first non-adjacent block is not coded with a spatial merge candidate.
• the first non-adjacent block is coded with merge mode and a motion refinement process.
• the first non-adjacent block is not coded with decoder-side motion vector refinement (DMVR).
• DMVR decoder-side motion vector refinement
• the method 2800 further includes selecting a second non- adjacent block.
• the first non-adjacent block and the second non-adjacent block are spatial neighbors of the current block, the first non-adjacent block is coded with a first mode, the second non-adjacent block is coded with a second mode, and the first non-adjacent block is selected prior to selecting the second non-adjacent block.
• motion information of the non-adjacent block is used as a predictor in an advanced motion vector prediction (AMVP) mode.
• AMVP advanced motion vector prediction
• the method 2800 includes, at step 2840, processing the current block based on the merge candidate list.
• the current block is decoded by pruning the merge candidate list and using the merge candidate list after the pruning.
• FIG. 29 is a block diagram of a video processing apparatus 2900.
• the apparatus 2900 may be used to implement one or more of the methods described herein.
• the apparatus 2900 may be embodied in a smartphone, tablet, computer, Internet of Things (IoT) receiver, and so on.
• the apparatus 2900 may include one or more processors 2902, one or more memories 2904 and video processing hardware 2906.
• the processor(s) 2902 may be configured to implement one or more methods (including, but not limited to, methods 2800) described in the present document.
• the memory (memories) 2904 may be used for storing data and code used for implementing the methods and techniques described herein.
• the video processing hardware 3006 may be used to implement, in hardware circuitry, some techniques described in the present document.
• a video decoder apparatus may implement a method of using zero-units as described herein is used for video decoding.
• the various features of the method may be similar to the above-described methods 2800.
• the video decoding methods may be implemented using a decoding apparatus that is implemented on a hardware platform as described with respect to FIG. 29.
• a method for video processing comprising: receiving a current block of video data; selecting, based on a rule, a first non-adjacent block that is not adjacent to the current block; constructing a merge candidate list including a first merge candidate comprising motion information based on the first non-adjacent block; and processing the current block based on the merge candidate list.
• the restricted region comprises a rectangular area of W samples by H samples, or wherein non-adjacent blocks with coordinates (NAx, NAy) statisfy one of the following conditions: NAx > ((Cx/W)*W), or NAx ⁇ ((Cx/W)*W)+W, or NAy > ((Cy/H)*H), or Nay ⁇ ((Cy/H)*H)+H.
• An apparatus comprising a processor and a non-transitory memory with instructions thereon, wherein the instructions upon execution by the processor, cause the processor to implement the method in any one of clauses 1 to 18.
• Implementations of the subject matter and the functional operations described in this patent document can be implemented in various systems, digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them.
• Implementations of the subject matter described in this specification can be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a tangible and non-transitory computer readable medium for execution by, or to control the operation of, data processing apparatus.
• the computer readable medium can be a machine- readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a machine-readable propagated signal, or a combination of one or more of them.
• data processing unit or“data processing apparatus” encompasses all apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, or multiple processors or computers.
• the apparatus can include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of them.
• a computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment.
• a computer program does not necessarily correspond to a file in a file system.
• a program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code).
• a computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.
• the processes and logic flows described in this specification can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output.
• the processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).
• processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer.
• a processor will receive instructions and data from a read only memory or a random access memory or both.
• the essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data.
• a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks.
• mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks.
• a computer need not have such devices.
• Computer readable media suitable for storing computer program instructions and data include all forms of nonvolatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices.
• semiconductor memory devices e.g., EPROM, EEPROM, and flash memory devices.
• the processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

Landscapes

• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Physics & Mathematics (AREA)
• Discrete Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Compression Or Coding Systems Of Tv Signals (AREA)

Applications Claiming Priority (4)

Publications (1)

Family

ID=67226319

Family Applications (1)

Country Status (3)

Families Citing this family (1)

Citations (1)

Family Cites Families (4)

• 2019
  • 2019-07-01 TW TW108123172A patent/TWI719524B/zh active
  • 2019-07-01 WO PCT/IB2019/055563 patent/WO2020008322A1/en active Application Filing
  • 2019-07-01 CN CN201910586397.XA patent/CN110677650B/zh active Active

Patent Citations (1)

Non-Patent Citations (2)

Also Published As

Similar Documents

Legal Events