CN110855998B

CN110855998B - Fusion candidate list construction method and device, and fusion candidate list editing/decoding method and device

Info

Publication number: CN110855998B
Application number: CN201811014507.7A
Authority: CN
Inventors: 杨海涛; 赵寅; 徐巍炜
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2018-08-20
Filing date: 2018-08-31
Publication date: 2023-04-11
Anticipated expiration: 2038-08-31
Also published as: CN110855998A

Abstract

The present invention provides a method for constructing a merge candidate list for inter prediction, comprising adding motion information of a neighboring block as a spatial merge candidate of a current block to a merge candidate list of the current block when the neighboring block is available and the motion information of the neighboring block is different from motion information of a neighboring block at a specific position; and when the inter prediction mode of at least one non-adjacent block in the non-adjacent blocks is judged to be a predetermined inter prediction mode under the condition that the non-adjacent blocks are available, not adding the non-adjacent spatial fusion candidate of the at least one non-adjacent block into the fusion candidate list of the current block.

Description

Fusion candidate list construction method and device, and encoding/decoding method and device

Technical Field

The present disclosure relates to the field of video coding, and more particularly, to a method for constructing a fusion candidate list in an inter-frame prediction mode in a video coding and decoding process, and a coding and decoding method applied thereto.

Background

Video encoding (video encoding and decoding) is widely used in digital video applications such as broadcast digital television, video dissemination over the internet and mobile networks, real-time session applications such as video chat and video conferencing, DVD and blu-ray discs, video content capture and editing systems, and security applications for camcorders.

With the development of the hybrid block-based video coding scheme in the h.261 standard in 1990, new video coding techniques and tools have been developed and form the basis of the evolution of the subsequent video coding standard. Video Coding standards include MPEG-1 Video, MPEG-2 Video, ITU-T H.262/MPEG-2, ITU-T H.263, ITU-T H.264/MPEG-4 part 10 Advanced Video Coding (AVC), ITU-T H.265/High Efficiency Video Coding (HEVC) … and extensions of such standards, such as scalability and/or 3D (three-dimensional) extensions. As video authoring and sharing becomes more widespread, video traffic becomes the greatest burden on communication networks and data storage. One of the goals of most video coding standards is therefore to reduce the bit rate without degrading the subjective quality of the picture compared to previous standards. Even though the latest High Efficiency Video Coding (HEVC) can compress Video twice as much as AVC without reducing the subjective quality of pictures, it is still urgently needed to further compress Video in comparison with HEVC, and a new generation of VVC (Video Coding) technology is being formulated, aiming at further improving the compression ratio by about 50% without reducing the subjective quality of pictures in comparison with HEVC.

In the HEVC/h.265 video Coding standard or the VVC/h.266 video Coding standard being established, a frame of picture is divided into non-overlapping Coding Tree Units (CTUs), and the size of the CTUs may be set to 64 × 64 or 128 × 128. Taking a CTU of size 64 × 64 as an example, it contains 64 columns of pixels, each column containing 64 pixels, each pixel containing a luminance component or/and a chrominance component. One CTU is divided into one or more Coding Units (CUs). A CU contains basic coding information including prediction mode, transform coefficients, etc. The decoding end may perform decoding processing such as prediction, inverse quantization, inverse transformation, reconstruction, and filtering on the CU according to the coding information, and generate a reconstructed image corresponding to the CU. One CU corresponds to a predicted image and a residual image, and the predicted image and the residual image are added to obtain a reconstructed image. The prediction image is generated by intra prediction or inter prediction, and the residual image is generated by inverse quantization and inverse transformation processing of the transformation coefficient.

Inter-frame prediction is a prediction technology based on motion compensation, and the main processing procedure is to determine motion information of a current block, obtain a reference image block from a reference frame of the current block according to the motion information, and generate a predicted image of the current block, where the current block refers to an image block undergoing encoding/decoding processing, and the current block may be a luminance block or a chrominance block in one encoding unit. The motion information includes inter prediction direction indicating which prediction direction the current block uses among forward prediction, backward prediction, or bi-directional prediction, reference frame, motion vector indicating a displacement vector of a reference image block in the reference frame used for predicting the current block with respect to the current block, and so on, and thus one motion vector corresponds to one reference frame. Inter prediction of an image block can generate a predicted image using pixels in a reference frame by only one motion vector, which is called unidirectional prediction; a prediction image can also be generated by two motion vectors using pixels in two reference frames in combination, called bi-prediction. That is, an image block may typically contain one or two motion vectors. For some multi-hypothesis inter prediction (multi-prediction) techniques, an image block may contain more than two motion vectors.

The inter prediction indicates a reference frame (reference frame) by a reference frame index (ref _ idx), and indicates a position offset of a reference block (reference block) of a current block in the reference frame relative to a current block in a current frame by a Motion Vector (MV). One MV is a two-dimensional vector containing a horizontal direction displacement component and a vertical direction displacement component; one MV corresponds to two frames, each having a Picture Order Count (POC) indicating the number of pictures in display order, so one MV also corresponds to one POC difference. The POC difference is linear with time interval. Scaling of motion vectors typically uses POC difference based scaling to convert a motion vector between one pair of pictures to a motion vector between another pair of pictures.

The following three inter prediction modes are commonly used:

1) AMVP mode (Advanced Motion Vector Prediction): identifying inter-frame prediction direction (forward, backward or bidirectional), reference frame index (reference index), motion vector predictor index (MVP index), and motion vector residual difference (MVD) used by the current block in the code stream; the reference frame queue used is determined by the inter-frame prediction direction, the reference frame pointed by the current block MV is determined by the reference frame index, one MVP in the MVP list is indicated by the motion vector predictor index to be used as the predictor of the current block MV, and one MVP and one MVD are added to obtain one MV.

2) merge/skip mode: identifying a merge index (merge index) in the bitstream, selecting a merge candidate from a merge candidate list (merge candidate list) according to the merge index, wherein the motion vector information (including prediction direction, reference frame, motion vector) of the current block is determined by the merge candidate. The merge mode and the skip mode are mainly different in that the merge mode implies that the current block has residual error information, that is, a motion vector acquired from a motion candidate list is used as a motion vector predicted value of the current block, the motion vector of the current block is obtained by adding the predicted value of the motion vector and the residual error value of the motion vector, and the residual error of the motion vector is obtained by decoding a code stream; the skip mode implies that the current block has no residual information (or the residual is 0), that is, the motion vector obtained from the motion vector list is directly used as the motion vector of the current block for inter-frame prediction; the two modes derive motion information in the same way.

3) Affine transformation mode: and obtaining the motion vector of each sub-block in the current block by two or three control point motion vectors through affine transformation.

In the HEVC standard, a fusion candidate may be motion information of an image block adjacent to a current block, referred to as a spatial fusion candidate (spatial fusion candidate); or motion information of the image block at the corresponding position of the current block in another coded image, called temporal fusion candidate (temporal fusion candidate). Further, the fusion candidate may be a bi-predictive fusion candidate (bi-predictive fusion candidate) in which forward motion information of one fusion candidate and backward motion information of another fusion candidate are combined, or a zero motion vector fusion candidate (zero motion vector fusion candidate) in which a motion vector is forced to be a 0 vector.

Technical proposals received in the latest conference established by the latest video standard VVC, such as JVET-K0286, JVET-K0198 and JVET-K0339, propose a method for adding non-adjacent spatial fusion candidates (non-adjacent spatial fusion candidates) in a fusion candidate list, increase the number of fusion candidates in merge/skip mode, and improve prediction efficiency.

The construction method of the fusion candidate list in JVET-K0286 proposal is as follows:

step 1: a spatial merge candidate (spatial merge candidate) spatially adjacent to the current block is added to the merge candidate list of the current block, which is the same as the method in HEVC. The spatially adjacent spatial fusion candidates are the motion information of the A, B, C, D, E block in fig. 1, and their order of adding to the fusion candidate list is A, B, C, D, E. In FIG. 1, the blocks A, B, C, …, I, etc. are all 4x4 blocks.

Step 2: the temporal fusion candidate (temporal fusion candidate) of the current block is added to the fusion candidate list of the current block, which is the same method as in HEVC.

And 3, step 3: adding a non-adjacent spatial blending candidate (non-adjacent spatial blending candidate) that is not adjacent to the current block spatial domain to the blending candidate list of the current block. The non-adjacent space fusion candidate is the motion information of the block A1, B1, C1, D1, E1, A2, B2, C2, D2, E2, F, G, H, I in FIG. 1; the order in which non-adjacent spatial fusion candidates join the fusion candidate list is A1, B1, C1, D1, E1, F, G, H, I, A, B2, C2, D2, E2. As a simplification, the jfet-K0286 proposal also proposes that non-neighboring spatial fusion candidates contain only motion information of A1, B1, C1, D1, E1, A2, B2, C2, D2, E2 blocks.

And 4, step 4: other types of fusion candidates are added, such as bi-predictive fusion candidates (bi-predictive fusion candidates) and zero motion vector fusion candidates (zero motion vector fusion candidates).

It should be noted that the length of the fusion candidate list is a preset fixed value M, for example, 6, 8, or 10, and when the number of fusion candidates in the fusion candidate list reaches the preset value M, the construction of the fusion candidate list is completed, and the remaining fusion candidates do not join the fusion candidate list any more. In addition, if a fusion candidate is the same as the existing fusion candidate in the fusion candidate list, the fusion candidate may not be added to the fusion candidate list, so as to avoid redundant information due to the repeated fusion candidates in the fusion candidate list.

More non-neighboring spatial fusion candidates were used in jfet-K0339, as shown in fig. 10. In fig. 10, blocks 1 to 5 are conventional spatial fusion candidates, and blocks 6 to 48 are non-neighboring spatial fusion candidates.

During decoding, if the current block uses a skip/merge mode, the merge index is analyzed from the code stream, and a merge candidate corresponding to the merge index is selected from the merge candidate list constructed by the method, so as to obtain the motion information of the current block. And performing motion compensation according to the motion information of the current block to obtain a predicted image of the current block. And adding the predicted image of the current block and the residual image of the current block to obtain a reconstructed image of the current block, thereby finishing the decoding of the current block.

In the multiple fusion proposed in the scheme, the number of non-adjacent space fusion candidates is large, the length of the fusion candidate list is small, and the fusion candidates are appropriately screened in the process of adding the fusion candidates into the fusion candidate list, so that the diversity of the fusion candidates in the fusion candidate list and the similarity between the fusion candidates and the motion information of the current block can be improved, and the prediction efficiency is improved.

In the method for adding more non-adjacent spatial fusion candidates (non-adjacent spatial fusion candidates) to the fusion candidate list proposed in the above scheme, the judgment rule for judging whether to add a non-trusted spatial fusion candidate to the fusion candidate list is to judge whether to add the non-adjacent spatial fusion candidate to the fusion candidate list according to whether a non-adjacent spatial fusion candidate is repeated with the existing fusion candidates in the fusion candidate list, which requires a relatively complex comparison logic. The motion information of the non-adjacent space fusion candidate using the skip/merge mode is easily repeated or similar to the motion information of the adjacent space fusion candidate, which is not beneficial to improving the diversity of the motion information in the fusion candidate list. In addition, if the non-adjacent spatial fusion candidate uses the affine model prediction mode and the current block uses the translational model prediction mode, the two regions have different motion types, so that the correlation between the non-adjacent spatial fusion candidate and the actual motion information of the current block is low, and the fusion candidate list should not be added.

Disclosure of Invention

In view of the above, the present invention provides a method and an apparatus for efficiently establishing a fusion candidate list, and a coding and decoding method and a coding and decoding apparatus using the same.

A first aspect of the present invention provides a method for constructing a fusion candidate list for inter prediction, which includes, when a neighboring block is available and motion information of the neighboring block is different from motion information of a neighboring block at a specific position, adding motion information of the neighboring block as a spatial fusion candidate of a current block to a fusion candidate list of the current block; and excluding motion information of a neighboring block of a specific prediction mode from a spatial fusion candidate list of the current block based on a motion prediction mode of a non-neighboring block, i.e., adding motion information of at least one of the non-neighboring blocks as a non-neighboring spatial fusion candidate of the current block to the fusion candidate list when it is judged that an inter prediction mode of the at least one of the non-neighboring blocks is not a predetermined inter prediction mode and the motion information of the at least one non-neighboring block is identical to motion information of a neighboring block of a specific position or a non-neighboring block, and not adding a non-neighboring spatial fusion candidate of the at least one non-neighboring block to the fusion candidate list of the current block when it is judged that the inter prediction mode of the at least one of the non-neighboring blocks is a predetermined inter prediction mode.

Based on the method, the invention can remove the fusion candidate which has weak correlation with the motion mode of the current block in the fusion candidate list, thereby having the opportunity to add more accurate and abundant fusion candidates into the fusion candidate list and improving the coding efficiency.

According to the first implementation manner of the first aspect of the present invention, the method may further add a temporal fusion candidate to the fusion candidate list, and the temporal fusion candidate may be preferably added to the fusion candidate list before adding a non-adjacent spatial fusion candidate, and specifically, before adding motion information of a non-adjacent block that is not spatially adjacent to the current block to the fusion candidate list of the current block as the non-adjacent spatial fusion candidate of the current block based on the preset second selection rule, add motion information of a bottom-right adjacent block of a collocated block in a reference frame of the current block to the fusion candidate list as a temporal fusion candidate of the current block, wherein the position of the collocated block in the reference frame is the same as the position of the current block in the current frame, or in case motion information of a bottom-right adjacent block of the collocated block is unavailable, add motion information of a center point of the collocated block to the fusion candidate list of the current block as the temporal fusion candidate of the current block.

With reference to the first aspect or the first implementation manner of the first aspect, in a second implementation manner of the present invention, if the number of fusion candidates in the fusion candidate list constructed by the method does not reach the predetermined number, in order to fully utilize the coding space provided by the fusion candidate list, another fusion candidate may be added to the fusion candidate list, preferably, after the motion information of a non-neighboring block that is not spatially adjacent to the current block is added to the fusion candidate list of the current block as a non-neighboring spatial fusion candidate of the current block based on a preset second selection rule, and the number of fusion candidates in the fusion candidate list does not reach the predetermined value, the method further includes: adding a bi-predictive fusion candidate to the fusion candidate list when the current block belongs to a bi-predictive slice (bi-predictive slice), or adding a zero motion vector fusion candidate to the fusion candidate list if the number of the fusion candidates in the fusion candidate list does not reach the predetermined value after the bi-predictive fusion candidate is added to the fusion candidate list; or adding a zero motion vector fusion candidate to the fusion candidate list when the current block belongs to a uni-predictive slice (uni-predictive slice).

With reference to the first aspect or any implementation manner of the first aspect, in a third implementation manner of the present invention, the predetermined inter-prediction mode is a skip/merge mode (skip/merge mode) or an Affine (Affine) transform prediction mode, or the inter-prediction mode is a skip/merge mode and an Affine (Affine) transform prediction mode. The specific prediction mode is not limited to the above-mentioned mode, and other inter prediction modes, such as an optical flow field mode, may be used as the predetermined inter prediction mode.

In order to reduce complexity, when there are multiple non-neighboring blocks that need to be determined, in combination with any of the embodiments of the first aspect or the first aspect of the present invention, in a fourth embodiment of the present invention, the non-neighboring blocks at a specific position are subjected to inter prediction mode determination, that is, only the non-neighboring blocks at the specific position are determined whether their inter prediction modes are the same as a predetermined inter prediction mode. The specific location may be, specifically, at least one of the non-adjacent blocks is an A2, B2, C2, D2, E2 block, where the upper left corner coordinate of the current block is P0= (x 0, y 0), the width and height of the current block are W and H, respectively, and the upper left corner coordinate of the A2 block is PA2= (x 0-4-2 × sx, y0+ H-4); the coordinates of the upper left corner of the B2 block are PB2= (x 0+ W-4, y0-4-2 sy); the coordinates of the top left corner of the C2 block are PC2= (x 0+ W, y0-4-2 sy); the coordinate of the upper left corner of the D2 block is PD2= (x 0-4-2 Sx, y0+ H); the coordinates of the upper left corner of the E2 block are PE2= (x 0-4-2 sx, y0-4-2 sy); or at least one of the non-adjacent blocks is an A1, B1, C2, D2, E2 block, the coordinate of the top left corner of the current block is P0= (x 0, y 0), the width and height of the current block are W and H, respectively, then the coordinate of the top left corner of the A1 block is PA1= (x 0-4-Sx, y0+ H-4); the coordinates of the upper left corner of the B1 block are PB1= (x 0+ W-4, y0-4-Sy); the coordinates of the top left corner of the C2 block are PC2= (x 0+ W, y0-4-2 sy); the coordinates of the upper left corner of the block D2 are PD2= (x 0-4-2 Sx, y0+ H); the coordinates of the upper left corner of the E2 block are PE2= (x 0-4-2 sx, y0-4-2 sy); or at least one of the non-adjacent blocks is an A1, B1, C1, D1, E1 block, the coordinate of the top left corner of the current block is P0= (x 0, y 0), the width and height of the current block are W and H, respectively, then the coordinate of the top left corner of the A1 block is PA1= (x 0-4-Sx, y0+ H-4); the coordinates of the upper left corner of the B1 block are PB1= (x 0+ W-4, y0-4-Sy); the coordinates of the upper left corner of the C1 block are PC2= (x 0+ W, y 0-4-Sy); the coordinate of the upper left corner of the D1 block is PD1= (x 0-4-Sx, y0+ H); the coordinate of the upper left corner of the E1 block is PE1= (x 0-4-Sx, y 0-4-Sy).

A second aspect of the present invention provides a decoding method, wherein a fusion candidate list constructed by the method according to the first aspect of the present invention or any implementation manner of the first aspect of the present invention is applied to a decoding process of the current block, and the decoding process includes: analyzing the code stream to obtain a fusion candidate index; acquiring a corresponding fusion candidate from the fusion candidate list according to the fusion candidate index and taking the fusion candidate as the motion information of the current block; performing inter-frame prediction on the current block according to the motion information of the current block to obtain a predicted image of the current block; acquiring a residual error image of the current block; and adding the predicted image of the current block and the residual image of the current block to obtain a reconstructed image of the current block. The decoding method provided by the second aspect of the present invention uses the fusion candidate list construction method provided by the first aspect of the present invention, so that the decoding efficiency can be effectively improved.

A third aspect of the present invention provides an encoding method, for use in a method for constructing a fusion candidate list for inter-frame prediction, wherein the fusion candidate list constructed by the method according to the first aspect of the present invention or any implementation manner of the first aspect of the present invention is applied to an encoding process of a current block, and the encoding process includes: performing RDO-based fusion evaluation (Merge evaluation) on the current block based on each fusion candidate in the fusion candidate list and taking the fusion candidate with the minimum rate distortion cost value as the motion information of the current block; encoding the current block based on the motion information of the current block to form encoded data; and adding the position index of the fusion candidate with the minimum rate distortion cost value in the fusion candidate list to the coded data.

The decoding method provided by the third aspect of the present invention uses the fusion candidate list construction method provided by the first aspect of the present invention, and can effectively improve the decoding efficiency.

The invention also provides an encoding device and an encoding device corresponding to the second aspect of the invention, and a decoding device corresponding to the third aspect of the invention.

Drawings

FIG. 1A is a block diagram of an example video encoding system for implementing an embodiment of the invention;

FIG. 1B is a block diagram showing an example of a video encoding system including either or both of the encoder 20 of FIG. 2 and the decoder 30 of FIG. 3;

FIG. 2 is a block diagram showing an example structure of a video encoder for implementing an embodiment of the present invention;

FIG. 3 is a block diagram showing an example structure of a video decoder for implementing an embodiment of the present invention;

FIG. 4 is a block diagram of an example of an encoding device or a decoding device;

FIG. 5 is a block diagram of another example of an encoding device or a decoding device;

fig. 6 is a flowchart of example operations of a video encoder implementing the fusion candidate list construction method of the present invention, in accordance with an embodiment;

fig. 7 is a flowchart of a decoding method of a video encoder decoding based on the fusion candidate list constructed in fig. 6, according to another embodiment;

fig. 8 is a flowchart of an encoding method in which a video encoder encodes based on the fusion candidate list constructed in fig. 6 according to another embodiment;

FIG. 9 is a schematic diagram of a distribution of spatially adjacent and non-adjacent blocks;

FIG. 10 is a schematic diagram of another arrangement of spatially adjacent and non-adjacent blocks.

Fig. 11 is a schematic structural diagram of a device for constructing a fusion candidate athlete list according to an embodiment of the present disclosure;

fig. 12 is a schematic structural diagram of a decoding apparatus according to an embodiment of the present application;

fig. 13 is a schematic structural diagram of an encoding apparatus according to an embodiment of the present application;

FIG. 14 is a schematic diagram of an apparatus for carrying out the methods of FIGS. 6-8 according to embodiments of the present disclosure;

in the following, identical reference signs refer to identical or at least functionally equivalent features, if no specific remarks are made with respect to the identical reference signs.

Detailed Description

Hereinafter, specific embodiments of the present invention and application examples using the specific embodiments of the present invention will be described with reference to the accompanying drawings.

It is to be understood that embodiments of the invention are not limited to the examples set forth herein, which may be used in other respects, and may include structural or logical changes not shown in the drawings.

For example, it should be understood that the disclosure in connection with the described methods may equally apply to the corresponding apparatus or system for performing the methods, and vice versa. For example, if one or more particular method steps are described, the corresponding apparatus may comprise one or more units, such as functional units, to perform the described one or more method steps (e.g., a unit performs one or more steps, or multiple units, each of which performs one or more of the multiple steps), even if such one or more units are not explicitly described or illustrated in the figures. On the other hand, for example, if a particular apparatus is described based on one or more units, such as functional units, the corresponding method may comprise one step to perform the functionality of the one or more units (e.g., one step performs the functionality of the one or more units, or multiple steps, each of which performs the functionality of one or more of the plurality of units), even if such one or more steps are not explicitly described or illustrated in the figures. Further, it is to be understood that features of the various exemplary embodiments and/or aspects described herein may be combined with each other, unless explicitly stated otherwise.

Video coding generally refers to processing a sequence of pictures that form a video or video sequence. In the field of video coding, the terms "picture", "frame" or "image" may be used as synonyms. Video encoding as used in this application (or this disclosure) refers to video encoding or video decoding. Video encoding is performed on the source side, typically including processing (e.g., by compressing) the original video picture to reduce the amount of data required to represent the video picture (and thus more efficiently store and/or transmit). Video decoding is performed at the destination side, typically involving inverse processing with respect to the encoder, to reconstruct the video pictures. Embodiments relate to video pictures (or collectively pictures, as will be explained below) "encoding" should be understood to refer to "encoding" or "decoding" of a video sequence. The combination of the encoding part and the decoding part is also called codec (coding and decoding).

In the case of lossless video coding, the original video picture can be reconstructed, i.e., the reconstructed video picture has the same quality as the original video picture (assuming no transmission loss or other data loss during storage or transmission). In the case of lossy video coding, the amount of data needed to represent the video picture is reduced by performing further compression, e.g., by quantization, while the decoder side cannot fully reconstruct the video picture, i.e., the quality of the reconstructed video picture is lower or worse than the quality of the original video picture.

Several video coding standards of h.261 belong to "lossy hybrid video codec" (i.e., the spatial and temporal prediction in the sample domain is combined with 2D transform coding in the transform domain for applying quantization). Each picture of a video sequence is typically partitioned into non-overlapping sets of blocks, typically encoded at the block level. In other words, the encoder side typically processes, i.e., encodes, video at the block (video block) level, e.g., generates a prediction block by spatial (intra-picture) prediction and temporal (inter-picture) prediction, subtracts the prediction block from the current block (currently processed or block to be processed) to obtain a residual block, transforms the residual block and quantizes the residual block in the transform domain to reduce the amount of data to be transmitted (compressed), while the decoder side applies the inverse processing portion relative to the encoder to the encoded or compressed block to reconstruct the current block for representation. In addition, the encoder replicates the decoder processing loop so that the encoder and decoder generate the same prediction (e.g., intra-prediction and inter-prediction) and/or reconstruction for processing, i.e., encoding, subsequent blocks.

As used herein, the term "block" may be a portion of a picture or frame. For ease of description, embodiments of the present invention are described with reference to VVC or High-Efficiency Video Coding (HEVC) developed by the Joint working Group of Video Coding (JCT-VC) of the ITU-T Video Coding Experts Group (VCEG) and the Motion Picture Experts Group (MPEG). Those of ordinary skill in the art understand that embodiments of the present invention are not limited to HEVC or VVC. May refer to CU, PU, and TU. In HEVC, the CTU is split into CUs by using a quadtree structure represented as a coding tree. The decision whether to encode a picture region using inter-picture (temporal) or intra-picture (spatial) prediction is made at the CU level. Each CU may be further split into one, two, or four PUs according to the PU split type. The same prediction process is applied within one PU and the relevant information is transmitted to the decoder on a PU basis. After obtaining the residual block by applying a prediction process based on the PU split type, the CU may be partitioned into Transform Units (TUs) according to other quadtree structures similar to the coding tree used for the CU. In a recent development of video compression technology, a coding block is partitioned using Quad-tree and binary tree (QTBT) partition frames. In the QTBT block structure, a CU may be square or rectangular in shape. In the VVC, a Coding Tree Unit (CTU) is first divided 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 the segments are used for prediction and transform processing without any other segmentation. This means that the block sizes of CU, PU and TU in the QTBT coding block structure are the same. Also, it has been proposed to use multiple partitions, such as ternary tree partitions, with QTBT block structures.

Embodiments of the encoder 20, decoder 30 and encoding system 10 are described below based on fig. 1A, 1B to 3 (before describing embodiments of the present invention in more detail based on fig. 6).

Fig. 1A is a conceptual or schematic block diagram of an exemplary encoding system 10, such as a video encoding system 10, that may utilize the techniques of this application (this disclosure). Encoder 20 (e.g., video encoder 20) and decoder 30 (e.g., video decoder 30) of video encoding system 10 represent examples of devices that may be used to perform techniques for fusion candidate list construction, and codec based on the post-fusion selection list, in accordance with various examples described herein. As shown in fig. 1A, encoding system 10 includes a source device 12 for providing encoded data 13, e.g., encoded pictures 13, to a destination device 14 that decodes encoded data 13, for example.

The source device 12 comprises an encoder 20 and may additionally, i.e. optionally, comprise a picture source 16, a pre-processing unit 18, e.g. a picture pre-processing unit 18, and a communication interface or unit 22.

The picture source 16 may include or may be any type of picture capture device for capturing real-world pictures, for example, and/or any type of picture or comment generation device (for screen content encoding, some text on the screen is also considered part of the picture or image to be encoded), for example, a computer graphics processor for generating computer animated pictures, or any type of device for obtaining and/or providing real-world pictures, computer animated pictures (e.g., screen content, virtual Reality (VR) pictures), and/or any combination thereof (e.g., augmented Reality (AR) pictures).

A (digital) picture is or can be seen as a two-dimensional array or matrix of sample points having intensity values. The sample points in the array may also be referred to as pixels (short for pixels) or pels (pels). The number of sample points in the array or picture in the horizontal and vertical directions (or axes) defines the size and/or resolution of the picture. To represent color, three color components are typically employed, i.e., a picture may be represented as or contain three sample arrays. In the RBG format or color space, a picture includes corresponding red, green, and blue sampling arrays. However, in video coding, each pixel is typically represented in a luminance/chrominance format or color space, e.g., YCbCr, comprising a luminance component (sometimes also indicated by L) indicated by Y and two chrominance components indicated by Cb and Cr. The luminance (or luma) component Y represents the luminance or gray level intensity (e.g., both are the same in a gray scale picture), while the two chrominance (or chroma) components Cb and Cr represent the chrominance or color information components. Accordingly, a picture in YCbCr format includes a luminance sample array of luminance sample values (Y), and two chrominance sample arrays of chrominance values (Cb and Cr). Pictures in RGB format may be converted or transformed into YCbCr format and vice versa, a process also known as color transformation or conversion. If the picture is black and white, the picture may include only an array of luminance samples.

Picture source 16 (e.g., video source 16) may be, for example, a camera for capturing pictures, a memory, such as a picture store, any type of (internal or external) interface that includes or stores previously captured or generated pictures, and/or acquires or receives pictures. The camera may be, for example, an integrated camera local or integrated in the source device, and the memory may be an integrated memory local or integrated in the source device, for example. The interface may be, for example, an external interface that receives pictures from an external video source, for example, an external picture capturing device such as a camera, an external memory, or an external picture generating device, for example, an external computer graphics processor, computer, or server. The interface may be any kind of interface according to any proprietary or standardized interface protocol, e.g. a wired or wireless interface, an optical interface. The interface for obtaining picture data 17 may be the same interface as communication interface 22 or may be part of communication interface 22.

Unlike pre-processing unit 18 and the processing performed by pre-processing unit 18, picture or picture data 17 (e.g., video data 16) may also be referred to as raw picture or raw picture data 17.

The pre-processing unit 18 is configured to receive (raw) picture data 17 and perform pre-processing on the picture data 17 to obtain a pre-processed picture 19 or pre-processed picture data 19. For example, the pre-processing performed by pre-processing unit 18 may include trimming, color format conversion (e.g., from RGB to YCbCr), toning, or denoising. It is to be understood that the pre-processing unit 18 may be an optional component.

Encoder 20, e.g., video encoder 20, is used to receive pre-processed picture data 19 and provide encoded picture data 21 (details will be described further below, e.g., based on fig. 2 or fig. 4). In one example, the encoder 20 may be configured to add motion information of a neighboring block spatially adjacent to a current block as a spatial fusion candidate of the current block into a fusion candidate list of the current block based on a preset first selection rule, where the preset first selection rule includes adding the motion information of the neighboring block as a spatial fusion candidate of the current block into the fusion candidate list of the current block when the neighboring block is available and the motion information of the neighboring block is different from the motion information of a neighboring block at a specific position; and adding motion information of a non-neighboring block spatially noncontiguous with the current block as a non-neighboring spatial fusion candidate of the current block into the fusion candidate list based on a preset second selection rule, wherein the current block has one or more spatially noncontiguous non-neighboring blocks, and the preset second selection rule comprises: when it is determined that the inter prediction mode of at least one of the non-neighboring blocks is not the predetermined inter prediction mode and the motion information of the at least one non-neighboring block is the same as the motion information of the neighboring block at the specific position or the non-neighboring block if the non-neighboring blocks are available, adding the motion information of the at least one non-neighboring block as a non-neighboring spatial fusion candidate of the current block into the fusion candidate list, and when it is determined that the inter prediction mode of at least one of the non-neighboring blocks is the predetermined inter prediction mode if the non-neighboring blocks are available, not adding the non-neighboring spatial fusion candidate of the at least one non-neighboring block into the fusion candidate list of the current block.

Communication interface 22 of source device 12 may be used to receive encoded picture data 21 and transmit to other devices, e.g., destination device 14 or any other device for storage or direct reconstruction, or to process encoded picture data 21 prior to correspondingly storing encoded data 13 and/or transmitting encoded data 13 to other devices, e.g., destination device 14 or any other device for decoding or storage.

Destination device 14 includes a decoder 30 (e.g., a video decoder 30), and may additionally, that is, optionally, include a communication interface or unit 28, a post-processing unit 32, and a display device 34.

Communication interface 28 of destination device 14 is used, for example, to receive encoded picture data 21 or encoded data 13 directly from source device 12 or any other source, such as a storage device, such as an encoded picture data storage device.

Communication interface 22 and communication interface 28 may be used to transmit or receive encoded picture data 21 or encoded data 13 by way of a direct communication link between source device 12 and destination device 14, such as a direct wired or wireless connection, or by way of any type of network, such as a wired or wireless network or any combination thereof, or any type of private and public networks, or any combination thereof.

Communication interface 22 may, for example, be used to encapsulate encoded picture data 21 into a suitable format, such as a packet, for transmission over a communication link or communication network.

Communication interface 28, which forms a corresponding part of communication interface 22, may for example be used to decapsulate encoded data 13 to obtain encoded picture data 21.

Both communication interface 22 and communication interface 28 may be configured as a unidirectional communication interface, as indicated by the arrow for encoded picture data 13 from source device 12 to destination device 14 in fig. 1A, or as a bidirectional communication interface, and may be used, for example, to send and receive messages to establish a connection, acknowledge and exchange any other information related to a communication link and/or a data transmission, e.g., an encoded picture data transmission.

Decoder 30 is for receiving encoded picture data 21 and providing decoded picture data 31 or decoded picture 31 (details will be described further below, e.g., based on fig. 3 or fig. 5). In one example, the decoder 30 may be configured to decode the data encoded by the encoder, which may specifically be parsing the code stream to obtain a fusion candidate index; acquiring a corresponding fusion candidate from the fusion candidate list according to the fusion candidate index and taking the fusion candidate as the motion information of the current block; performing inter-frame prediction on the current block according to the motion information of the current block to obtain a predicted image of the current block; acquiring a residual error image of the current block; and adding the predicted image of the current block and the residual image of the current block to obtain a reconstructed image of the current block.

Post-processor 32 of destination device 14 is used to post-process decoded picture data 31 (also referred to as reconstructed picture data), e.g., decoded picture 131, to obtain post-processed picture data 33, e.g., post-processed picture 33. Post-processing performed by post-processing unit 32 may include, for example, color format conversion (e.g., from YCbCr to RGB), toning, cropping, or resampling, or any other processing for, for example, preparing decoded picture data 31 for display by display device 34.

Display device 34 of destination device 14 is used to receive post-processed picture data 33 to display a picture to, for example, a user or viewer. Display device 34 may be or may include any type of display for presenting the reconstructed picture, such as an integrated or external display or monitor. For example, the display may include a Liquid Crystal Display (LCD), an Organic Light Emitting Diode (OLED) display, a plasma display, a projector, a micro LED display, a liquid crystal on silicon (LCoS), a Digital Light Processor (DLP), or any other display of any kind.

Although fig. 1A depicts source apparatus 12 and destination apparatus 14 as separate apparatuses, an apparatus embodiment may also include the functionality of both source apparatus 12 and destination apparatus 14 or both, i.e., source apparatus 12 or corresponding functionality and destination apparatus 14 or corresponding functionality. In such embodiments, source device 12 or corresponding functionality and destination device 14 or corresponding functionality may be implemented using the same hardware and/or software, or using separate hardware and/or software, or any combination thereof.

It will be apparent to those skilled in the art from this description that the existence and (exact) division of the functionality of the different elements, or source device 12 and/or destination device 14 as shown in fig. 1A, may vary depending on the actual device and application.

Encoder 20 (e.g., video encoder 20) and decoder 30 (e.g., video decoder 30) may each be implemented as any of a variety of suitable circuitry, such as one or more microprocessors, digital Signal Processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), discrete logic, hardware, or any combinations thereof. If the techniques are implemented in part in software, an apparatus may store instructions of the software in a suitable non-transitory computer-readable storage medium and may execute the instructions in hardware using one or more processors to perform the techniques of this disclosure. Any of the foregoing, including hardware, software, a combination of hardware and software, etc., may be considered one or more processors. Each of video encoder 20 and video decoder 30 may be included in one or more encoders or decoders, either of which may be integrated as part of a combined encoder/decoder (codec) in a corresponding device.

Source device 12 may be referred to as a video encoding device or a video encoding apparatus. Destination device 14 may be referred to as a video decoding device or a video decoding apparatus. Source device 12 and destination device 14 may be examples of video encoding devices or video encoding apparatus.

Source device 12 and destination device 14 may comprise any of a variety of devices, including any type of handheld or stationary device, such as a notebook or laptop computer, a mobile phone, a smart phone, a tablet or tablet computer, a camcorder, a desktop computer, a set-top box, a television, a display device, a digital media player, a video game console, a video streaming device (e.g., a content service server or a content distribution server), a broadcast receiver device, a broadcast transmitter device, etc., and may not use or use any type of operating system.

In some cases, source device 12 and destination device 14 may be equipped for wireless communication. Thus, source device 12 and destination device 14 may be wireless communication devices.

In some cases, the video encoding system 10 shown in fig. 1A is merely an example, and the techniques of this application may be applicable to video encoding settings (e.g., video encoding or video decoding) that do not necessarily involve any data communication between the encoding and decoding devices. In other examples, the data may be retrieved from local storage, streamed over a network, and so on. A video encoding device may encode and store data to memory, and/or a video decoding device may retrieve and decode data from memory. In some examples, the encoding and decoding are performed by devices that do not communicate with each other, but merely encode data to and/or retrieve data from memory and decode data.

It should be understood that for each of the examples described above with reference to video encoder 20, video decoder 30 may be used to perform the reverse process. With respect to signaling syntax elements, video decoder 30 may be configured to receive and parse such syntax elements and decode the associated video data accordingly. In some examples of the present invention, video encoder 20 may entropy encode into the encoded video bitstream one or more syntax elements defining a particular position of a fusion candidate in a fusion candidate list and syntax elements of an inter-coding type of a spatial non-neighboring block of the current block. In such instances, video decoder 30 may parse such syntax elements and decode the relevant video data accordingly.

Fig. 1B is an illustration of an example of a video encoding system 40 including encoder 20 of fig. 2 and/or decoder 30 of fig. 3, according to an example embodiment. The system 40 may implement the technology of the present application for constructing a fusion candidate list of a current block based on the fusion candidate construction method proposed by the present invention, and encoding or decoding an image based on the fusion candidate list. In the illustrated embodiment, video encoding system 40 may include an imaging device 41, video encoder 20, video decoder 30 (and/or a video encoder implemented by logic 47 of processing unit 46), an antenna 42, one or more processors 43, one or more memories 44, and/or a display device 45.

As shown, the imaging device 41, the antenna 42, the processing unit 46, the logic circuit 47, the video encoder 20, the video decoder 30, the processor 43, the memory 44, and/or the display device 45 are capable of communicating with each other. As discussed, although video encoding system 40 is depicted with video encoder 20 and video decoder 30, in different examples, video encoding system 40 may include only video encoder 20 or only video decoder 30.

In some examples, as shown, video encoding system 40 may include an antenna 42. For example, the antenna 42 may be used to transmit or receive an encoded bitstream of video data. Additionally, in some examples, video encoding system 40 may include a display device 45. Display device 45 may be used to present video data. In some examples, logic 47 may be implemented by processing unit 46, as shown. The processing unit 46 may comprise application-specific integrated circuit (ASIC) logic, a graphics processor, a general-purpose processor, or the like. Video coding system 40 may also include an optional processor 43, which optional processor 43 similarly may include application-specific integrated circuit (ASIC) logic, a graphics processor, a general-purpose processor, or the like. In some examples, the logic 47 may be implemented in hardware, such as video encoding specific hardware, and the processor 43 may be implemented in general purpose software, an operating system, and so on. In addition, the Memory 44 may be any type of Memory, such as a volatile Memory (e.g., static Random Access Memory (SRAM), dynamic Random Access Memory (DRAM), etc.) or a nonvolatile Memory (e.g., flash Memory, etc.), and the like. In a non-limiting example, storage 44 may be implemented by a speed cache memory. In some instances, logic circuitry 47 may access memory 44 (e.g., to implement an image buffer). In other examples, logic 47 and/or processing unit 46 may include memory (e.g., cache, etc.) for implementing image buffers, etc.

In some examples, video encoder 20, implemented by logic circuitry, may include an image buffer (e.g., implemented by processing unit 46 or memory 44) and a graphics processing unit (e.g., implemented by processing unit 46). The graphics processing unit may be communicatively coupled to the image buffer. The graphics processing unit may include video encoder 20 implemented by logic circuitry 47 to implement the various modules discussed with reference to fig. 2 and/or any other encoder system or subsystem described herein. Logic circuitry may be used to perform various operations discussed herein.

Video decoder 30 may be implemented in a similar manner by logic circuitry 47 to implement the various modules discussed with reference to decoder 30 of fig. 3 and/or any other decoder system or subsystem described herein. In some examples, logic circuit implemented video decoder 30 may include an image buffer (implemented by processing unit 2820 or memory 44) and a graphics processing unit (e.g., implemented by processing unit 46). The graphics processing unit may be communicatively coupled to the image buffer. The graphics processing unit may include video decoder 30 implemented by logic circuitry 47 to implement the various modules discussed with reference to fig. 3 and/or any other decoder system or subsystem described herein.

In some examples, antenna 42 of video encoding system 40 may be used to receive an encoded bitstream of video data. As discussed, the encoded bitstream may include data related to the encoded video frame, indicators, index values, mode selection data, etc., discussed herein, such as data related to the encoding partition (e.g., transform coefficients or quantized transform coefficients, (as discussed) optional indicators, and/or data defining the encoding partition). Video encoding system 40 may also include a video decoder 30 coupled to antenna 42 and configured to decode the encoded bitstream. The display device 45 is used to present video frames.

Encoder and encoding method

Fig. 2 shows a schematic/conceptual block diagram of an example of a video encoder 20 for implementing the techniques of this disclosure. In the example of fig. 2, video encoder 20 includes a residual calculation unit 204, a transform processing unit 206, a quantization unit 208, an inverse quantization unit 210, an inverse transform processing unit 212, a reconstruction unit 214, a buffer 216, a loop filter unit 220, a Decoded Picture Buffer (DPB) 230, a prediction processing unit 260, and an entropy encoding unit 270. Prediction processing unit 260 may include inter prediction unit 244, intra prediction unit 254, and mode selection unit 262. Inter prediction unit 244 may include a motion estimation unit and a motion compensation unit (not shown). The video encoder 20 shown in fig. 2 may also be referred to as a hybrid video encoder or a video encoder according to a hybrid video codec.

For example, the residual calculation unit 204, the transform processing unit 206, the quantization unit 208, the prediction processing unit 260, and the entropy encoding unit 270 form a forward signal path of the encoder 20, and, for example, the inverse quantization unit 210, the inverse transform processing unit 212, the reconstruction unit 214, the buffer 216, the loop filter 220, the Decoded Picture Buffer (DPB) 230, the prediction processing unit 260 form a backward signal path of the encoder, wherein the backward signal path of the encoder corresponds to a signal path of a decoder (see the decoder 30 in fig. 3).

Encoder 20 receives picture 201 or block 203 of picture 201, e.g., a picture in a sequence of pictures forming a video or video sequence, e.g., via input 202. Picture block 203 may also be referred to as a current picture block or a picture block to be encoded, and picture 201 may be referred to as a current picture or a picture to be encoded (especially when the current picture is distinguished from other pictures in video encoding, such as previously encoded and/or decoded pictures in the same video sequence, i.e., a video sequence that also includes the current picture).

Segmentation

An embodiment of encoder 20 may include a partitioning unit (not shown in fig. 2) for partitioning picture 201 into a plurality of blocks, such as block 203, typically into a plurality of non-overlapping blocks. The partitioning unit may be used to use the same block size for all pictures in a video sequence and a corresponding grid defining the block size, or to alter the block size between pictures or subsets or groups of pictures and partition each picture into corresponding blocks. A quadtree-binary-tree (QTBT) partitioning technique proposed by j.an et al in a Block partitioning structure for next generation video coding (international telecommunications union, COM16-C966, 9 months 2015, hereinafter referred to as "VCEG recommendation COM 16-C966") was introduced in VVC. Simulations have shown that the proposed QTBT structure is more efficient than the quadtree structure in HEVC used. Furthermore, in QTBT, a CU may have a square or rectangular shape. As shown in fig. 3, a Coding Tree Unit (CTU) is first divided by a quad tree structure. The quadtree leaf nodes may be further partitioned by a binary tree structure. There are two partition types in binary tree partitioning: symmetrical horizontal division and symmetrical vertical division. In each case, the nodes are divided by horizontally or vertically bisecting the nodes along the middle. The binary tree leaf nodes are called Coding Units (CUs) and are each processed for prediction and transformation without any further partitioning. This means that CU, PU and TU have the same block size in the QTBT coding block structure. CUs are sometimes made up of Coded Blocks (CBs) with different color components, for example, in 4:2: in the case of the P, B stripe of the 0 chroma format, one CU contains one luma CB and two chroma CBs, and sometimes consists of CBs having a single component, e.g., in the case of an I stripe, one CU contains only one luma CB or only two chroma CBs.

In addition, a block partitioning structure named a multi-type-tree (MTT) is proposed in U.S. patent application publication No. 20170208336 instead of a CU structure based on QT, BT and/or QTBT. The MTT partition structure is still a recursive tree structure. In MTT, a plurality of different division structures (e.g., three or more) are used. For example, according to the MTT technique, three or more different partitioning structures may be used at each depth of the tree structure for each respective non-leaf node of the tree structure. The depth of a node in the tree structure may refer to the length of the path (e.g., number of splits) from the node to the root of the tree structure. The partition structure may generally refer to how many different blocks a block may be divided into. The partition structure may be a quad tree partition structure that may divide a block into four blocks, a binary tree partition structure that may divide a block into two blocks, or a tri tree partition structure that may divide a block into three blocks, and furthermore, the tri tree partition structure may not divide a block through the center. The partition structure may have a plurality of different partition types. The partition type may additionally define how the blocks are partitioned, including symmetric or asymmetric partitions, uniform or non-uniform partitions, and/or horizontal or vertical partitions.

In MTT, at each depth of the tree structure, the encoder 100 may be used to further partition the subtree using a particular partition type of one of three additional partition structures. For example, the encoder 100 may be used to determine a particular partition type from QT, BT, triple-tree (TT), and other partition structures. In one example, the QT partition structure may contain a square quadtree or a rectangular quadtree partition type. The encoder 100 may use square quadtree partitioning to partition square blocks by dividing the blocks into four equally sized square blocks horizontally and vertically along the center. Likewise, the encoder 100 may use rectangular quadtree partitioning to partition a rectangular (e.g., non-square) block by bisecting the rectangular block into four equally sized rectangular blocks horizontally and vertically along the center.

The BT partition structure may include at least one of a horizontally symmetric binary tree, a vertically symmetric binary tree, a horizontally asymmetric binary tree, or a vertically asymmetric binary tree partition type. For the horizontal symmetric binary tree splitting type, the encoder 100 may be used to split a block horizontally into two symmetric blocks of the same size along the center of the block. For the vertical symmetric binary tree partition type, the encoder 100 may be used to vertically bisect a block into two symmetric blocks of the same size along the center of the block. For the horizontally asymmetric binary tree partition type, the encoder 100 may be used to horizontally partition a block into two blocks of different sizes. For example, one block may be 1/4 of the parent block size, while another block may be 3/4 of the parent block size, similar to a PART _2N × nU or PART _2N × nD partition type. For the vertical asymmetric binary tree partition type, the encoder 100 may be used to vertically partition a block into two blocks of different sizes. For example, one block may be 1/4 of the parent block size and another block may be 3/4 of the parent block size, similar to the PART _ nL × 2N or PART _ nR × 2N partition types. In other examples, the asymmetric binary tree partition type may partition a parent block into different sized portions. For example, one sub-block may be 3/8 of the parent block, while another sub-block may be 5/8 of the parent block. Of course, such division type may be a vertical type or a horizontal type.

The TT division structure is different from the type of QT or BT structure in that the TT division structure does not divide blocks along the center. The central regions of the blocks remain together in the same sub-block. Instead of generating a QT for four blocks or generating a binary tree for two blocks, the partitioning according to the TT partitioning structure generates three blocks. Example partition types of the partition structure according to TT include a symmetric partition type (both horizontal and vertical) and an asymmetric partition type (both horizontal and vertical). Further, the symmetric division type according to the TT division structure may be unequal/uneven or equal/even. The asymmetric partition type according to the TT partition structure is not uniform/uniform. In one example, the TT partition structure may contain at least one of the following partition types: a horizontal equal/uniform symmetric ternary tree, a vertical equal/uniform symmetric ternary tree, a horizontal unequal/non-uniform symmetric ternary tree, a vertical unequal/non-uniform symmetric ternary tree, a horizontal unequal/non-uniform asymmetric ternary tree, or a vertical unequal/non-uniform asymmetric ternary tree partition type.

In general, an unequal/unequal symmetric trilinear tree partition type is a partition type that is symmetric around the centerline of a block but where the size of at least one of the resulting three blocks is not the same as the other two. A preferred example is where the side blocks are 1/4 of the block size and the center block is 1/2 of the block size. The equal/uniform symmetric treble partition type is a partition type that is symmetric around the center line of a block and the sizes of the resulting blocks are all the same. Such a division is possible if the block height or width, depending on the vertical or horizontal division, is an integer multiple of 3. An unequal/unequal asymmetric ternary tree partition type is a partition type that is not symmetric about a centerline of a block and in which at least one of the resulting blocks is not equally sized to the other two.

In one example, prediction processing unit 260 of video encoder 20 may be used to perform any combination of the above-described segmentation techniques.

Like picture 201, block 203 is also or can be viewed as a two-dimensional array or matrix of sample points having intensity values (sample values), although smaller in size than picture 201. In other words, the block 203 may comprise, for example, one sample array (e.g., a luma array in the case of a black and white picture 201) or three sample arrays (e.g., a luma array and two chroma arrays in the case of a color picture) or any other number and/or class of arrays depending on the color format applied. The number of sampling points in the horizontal and vertical directions (or axes) of the block 203 defines the size of the block 203.

The encoder 20 as shown in fig. 2 is used to encode a picture 201 block by block, e.g., performing encoding and prediction for each block 203.

Residual calculation

The residual calculation unit 204 is configured to calculate a residual block 205 based on the picture block 203 and the prediction block 265 (further details of the prediction block 265 are provided below), e.g. by subtracting sample values of the picture block 203 from sample values of the prediction block 265 on a sample-by-sample (pixel-by-pixel) basis to obtain the residual block 205 in the sample domain.

Transformation of

The transform processing unit 206 is configured to apply a transform, such as a Discrete Cosine Transform (DCT) or a Discrete Sine Transform (DST), on the sample values of the residual block 205 to obtain transform coefficients 207 in a transform domain. The transform coefficients 207 may also be referred to as transform residual coefficients and represent the residual block 205 in the transform domain.

The transform processing unit 206 may be used to apply integer approximations of DCT/DST, such as the transform specified for HEVC/h.265. Such integer approximations are typically scaled by some factor compared to the orthogonal DCT transform. To maintain the norm of the residual block processed by the forward transform and the inverse transform, an additional scaling factor is applied as part of the transform process. The scaling factor is typically selected based on certain constraints, e.g., the scaling factor is a power of 2 for a shift operation, a trade-off between bit depth of transform coefficients, accuracy and implementation cost, etc. For example, a specific scaling factor may be specified on the decoder 30 side for the inverse transform by, for example, inverse transform processing unit 212 (and on the encoder 20 side for the corresponding inverse transform by, for example, inverse transform processing unit 212), and correspondingly, a corresponding scaling factor may be specified on the encoder 20 side for the forward transform by transform processing unit 206.

Quantization

Quantization unit 208 is used to quantize transform coefficients 207, e.g., by applying scalar quantization or vector quantization, to obtain quantized transform coefficients 209. Quantized transform coefficients 209 may also be referred to as quantized residual coefficients 209. The quantization process may reduce the bit depth associated with some or all of transform coefficients 207. For example, an n-bit transform coefficient may be rounded down to an m-bit transform coefficient during quantization, where n is greater than m. The quantization level may be modified by adjusting a Quantization Parameter (QP). For example, for scalar quantization, different scales may be applied to achieve finer or coarser quantization. Smaller quantization steps correspond to finer quantization and larger quantization steps correspond to coarser quantization. An appropriate quantization step size may be indicated by a Quantization Parameter (QP). For example, the quantization parameter may be an index of a predefined set of suitable quantization step sizes. For example, a smaller quantization parameter may correspond to a fine quantization (smaller quantization step size) and a larger quantization parameter may correspond to a coarse quantization (larger quantization step size), or vice versa. The quantization may comprise a division by a quantization step size and a corresponding quantization or inverse quantization, e.g. performed by inverse quantization 210, or may comprise a multiplication by a quantization step size. Embodiments according to some standards, such as HEVC, may use a quantization parameter to determine the quantization step size. In general, the quantization step size may be calculated based on the quantization parameter using a fixed point approximation of an equation that includes division. Additional scaling factors may be introduced for quantization and dequantization to recover the norm of the residual block that may be modified due to the scale used in the fixed point approximation of the equation for the quantization step size and quantization parameter. In one example embodiment, the inverse transform and inverse quantization scales may be combined. Alternatively, a custom quantization table may be used and signaled from the encoder to the decoder, e.g., in a bitstream. Quantization is a lossy operation, where the larger the quantization step size, the greater the loss.

The inverse quantization unit 210 is configured to apply inverse quantization of the quantization unit 208 on the quantized coefficients to obtain inverse quantized coefficients 211, e.g., to apply an inverse quantization scheme of the quantization scheme applied by the quantization unit 208 based on or using the same quantization step as the quantization unit 208. The dequantized coefficients 211 may also be referred to as dequantized residual coefficients 211, corresponding to transform coefficients 207, although the loss due to quantization is typically not the same as the transform coefficients.

The inverse transform processing unit 212 is configured to apply an inverse transform of the transform applied by the transform processing unit 206, for example, inverse Discrete Cosine Transform (DCT) or inverse Discrete Sine Transform (DST), to obtain an inverse transform block 213 in the sample domain. The inverse transform block 213 may also be referred to as an inverse transform dequantized block 213 or an inverse transform residual block 213.

The reconstruction unit 214 (e.g., summer 214) is used to add the inverse transform block 213 (i.e., the reconstructed residual block 213) to the prediction block 265 to obtain the reconstructed block 215 in the sample domain, e.g., to add sample values of the reconstructed residual block 213 to sample values of the prediction block 265.

Optionally, a buffer unit 216 (or simply "buffer" 216), such as a line buffer 216, is used to buffer or store the reconstructed block 215 and corresponding sample values, for example, for intra prediction. In other embodiments, the encoder may be used to use the unfiltered reconstructed block and/or corresponding sample values stored in buffer unit 216 for any class of estimation and/or prediction, such as intra prediction.

For example, embodiments of encoder 20 may be configured such that buffer unit 216 is used not only to store reconstructed block 215 for intra prediction 254, but also for loop filter unit 220 (not shown in fig. 2), and/or such that buffer unit 216 and decoded picture buffer unit 230 form one buffer, for example. Other embodiments may be used to use filtered block 221 and/or blocks or samples from decoded picture buffer 230 (neither shown in fig. 2) as input or basis for intra prediction 254.

The loop filter unit 220 (or simply "loop filter" 220) is used to filter the reconstructed block 215 to obtain a filtered block 221, so as to facilitate pixel transition or improve video quality. Loop filter unit 220 is intended to represent one or more loop filters, such as a deblocking filter, a sample-adaptive offset (SAO) filter, or other filters, such as a bilateral filter, an Adaptive Loop Filter (ALF), or a sharpening or smoothing filter, or a collaborative filter. Although loop filter unit 220 is shown in fig. 2 as an in-loop filter, in other configurations, loop filter unit 220 may be implemented as a post-loop filter. The filtered block 221 may also be referred to as a filtered reconstructed block 221. The decoded picture buffer 230 may store the reconstructed encoded block after the loop filter unit 220 performs a filtering operation on the reconstructed encoded block.

Embodiments of encoder 20 (correspondingly, loop filter unit 220) may be used to output loop filter parameters (e.g., sample adaptive offset information), e.g., directly or after entropy encoding by entropy encoding unit 270 or any other entropy encoding unit, e.g., such that decoder 30 may receive and apply the same loop filter parameters for decoding.

Decoded Picture Buffer (DPB) 230 may be a reference picture memory that stores reference picture data for use by video encoder 20 in encoding video data. DPB 230 may be formed from any of a variety of memory devices, such as Dynamic Random Access Memory (DRAM) including Synchronous DRAM (SDRAM), magnetoresistive RAM (MRAM), resistive RAM (RRAM), or other types of memory devices. The DPB 230 and the buffer 216 may be provided by the same memory device or separate memory devices. In a certain example, a Decoded Picture Buffer (DPB) 230 is used to store filtered blocks 221. Decoded picture buffer 230 may further be used to store other previously filtered blocks, such as previously reconstructed and filtered blocks 221, of the same current picture or of a different picture, such as a previously reconstructed picture, and may provide the complete previously reconstructed, i.e., decoded picture (and corresponding reference blocks and samples) and/or partially reconstructed current picture (and corresponding reference blocks and samples), e.g., for inter prediction. In a certain example, if reconstructed block 215 is reconstructed without in-loop filtering, decoded Picture Buffer (DPB) 230 is used to store reconstructed block 215.

Prediction processing unit 260, also referred to as block prediction processing unit 260, is used to receive or obtain block 203 (current block 203 of current picture 201) and reconstructed picture data, e.g., reference samples of the same (current) picture from buffer 216 and/or reference picture data 231 of one or more previously decoded pictures from decoded picture buffer 230, and to process such data for prediction, i.e., to provide prediction block 265, which may be inter-predicted block 245 or intra-predicted block 255.

The mode selection unit 262 may be used to select a prediction mode (e.g., intra or inter prediction mode) and/or a corresponding prediction block 245 or 255 used as the prediction block 265 to calculate the residual block 205 and reconstruct the reconstructed block 215.

Embodiments of mode selection unit 262 may be used to select prediction modes (e.g., from those supported by prediction processing unit 260) that provide the best match or minimum residual (minimum residual means better compression in transmission or storage), or that provide the minimum signaling overhead (minimum signaling overhead means better compression in transmission or storage), or both. The mode selection unit 262 may be configured to determine a prediction mode based on Rate Distortion Optimization (RDO), i.e., select a prediction mode that provides the minimum rate distortion optimization, or select a prediction mode in which the associated rate distortion at least meets the prediction mode selection criteria.

The prediction processing performed by the example of the encoder 20 (e.g., by the prediction processing unit 260) and the mode selection performed (e.g., by the mode selection unit 262) will be explained in detail below.

As described above, the encoder 20 is configured to determine or select the best or optimal prediction mode from a set of (predetermined) prediction modes. The set of prediction modes may include, for example, intra-prediction modes and/or inter-prediction modes.

The intra prediction mode set may include 35 different intra prediction modes, for example, non-directional modes such as DC (or mean) mode and planar mode, or directional modes as defined in h.265, or may include 67 different intra prediction modes, for example, non-directional modes such as DC (or mean) mode and planar mode, or directional modes as defined in h.266 under development.

The set of (possible) inter prediction modes depends on the available reference pictures (i.e., at least partially decoded pictures stored in the DBP 230, for example, as described above) and other inter prediction parameters, e.g., on whether to use the entire reference picture or only a portion of the reference picture, such as a search window region of a region surrounding the current block, to search for a best matching reference block, and/or, e.g., on whether to apply pixel interpolation such as half-pixel and/or quarter-pixel interpolation.

In addition to the above prediction mode, a skip mode and/or a direct mode may also be applied.

The prediction processing unit 260 may further be used for partitioning the block 203 into smaller block partitions or sub-blocks, for example, by iteratively using quad-tree (QT) partitioning, binary-tree (BT) partitioning, or ternary-tree (TT) partitioning, or any combination thereof, and for performing prediction, for example, for each of the block partitions or sub-blocks, wherein the mode selection includes selecting a tree structure of the partitioned block 203 and selecting a prediction mode to apply to each of the block partitions or sub-blocks.

The inter prediction unit 244 may include a Motion Estimation (ME) unit (not shown in fig. 2) and a Motion Compensation (MC) unit (not shown in fig. 2). The motion estimation unit is used to receive or obtain picture block 203 (current picture block 203 of current picture 201) and decoded picture 231, or at least one or more previously reconstructed blocks, e.g., reconstructed blocks of one or more other/different previously decoded pictures 231, for motion estimation. For example, the video sequence may comprise a current picture and a previously decoded picture 31, or in other words, the current picture and the previously decoded picture 31 may be part of, or form, a sequence of pictures forming the video sequence. The construction of the fusion candidate list of the present application can be realized by the motion estimation module.

For example, the encoder 20 may be used to select a reference block from multiple reference blocks of the same or different one of multiple other pictures and provide the reference picture (or reference picture index … …) and/or an offset (spatial offset) between the location of the reference block (X, Y coordinates) and the location of the current block to a motion estimation unit (not shown in fig. 2) as an inter prediction parameter. This offset is also called a Motion Vector (MV).

The motion compensation unit is used to obtain, e.g., receive, inter-prediction parameters and perform inter-prediction based on or using the inter-prediction parameters to obtain the inter-prediction block 245. The motion compensation performed by the motion compensation unit (not shown in fig. 2) may involve taking or generating a prediction block based on a motion/block vector determined by motion estimation (possibly performing interpolation to sub-pixel precision). Interpolation filtering may generate additional pixel samples from known pixel samples, potentially increasing the number of candidate prediction blocks that may be used to encode a picture block. Upon receiving the motion vector for the PU of the current picture block, motion compensation unit 246 may locate the prediction block pointed to by the motion vector in one reference picture list. Motion compensation unit 246 may also generate syntax elements associated with the blocks and video slices for use by video decoder 30 in decoding picture blocks of the video slices.

The intra prediction unit 254 is used to obtain, e.g., receive, the picture block 203 (current picture block) of the same picture and one or more previously reconstructed blocks, e.g., reconstructed neighboring blocks, for intra estimation. For example, the encoder 20 may be configured to select an intra-prediction mode from a plurality of (predetermined) intra-prediction modes.

Embodiments of encoder 20 may be used to select an intra prediction mode based on optimization criteria, such as based on a minimum residual (e.g., an intra prediction mode that provides a prediction block 255 most similar to current picture block 203) or a minimum code rate distortion (e.g., … …).

The intra-prediction unit 254 is further configured to determine the intra-prediction block 255 based on the intra-prediction parameters as the selected intra-prediction mode. In any case, after selecting the intra-prediction mode for the block, intra-prediction unit 254 is also used to provide intra-prediction parameters, i.e., information indicating the selected intra-prediction mode for the block, to entropy encoding unit 270. In one example, intra-prediction unit 254 may be used to perform any combination of the intra-prediction techniques described below.

Entropy encoding unit 270 is configured to apply an entropy encoding algorithm or scheme (e.g., a Variable Length Coding (VLC) scheme, a Context Adaptive VLC (CAVLC) scheme, an arithmetic coding scheme, a context adaptive binary arithmetic coding (SBAC), a syntax-based context-adaptive binary arithmetic coding (syntax-based) coding, a Probability Interval Partitioning Entropy (PIPE) coding, or other entropy encoding methods or techniques) to individual or all of quantized residual coefficients 209, inter-prediction parameters, intra-prediction parameters, and/or loop filter parameters (or not) to obtain encoded picture data 21 that may be output by output 272 in the form of, for example, encoded bitstream 21. The encoded bitstream may be transmitted to video decoder 30 or archived for later transmission or retrieval by video decoder 30. Entropy encoding unit 270 may also be used to entropy encode other syntax elements of the current video slice being encoded.

Other structural variations of video encoder 20 may be used to encode the video stream. For example, non-transform based encoder 20 may quantize the residual signal directly without transform processing unit 206 for certain blocks or frames. In another embodiment, encoder 20 may have quantization unit 208 and inverse quantization unit 210 combined into a single unit.

Fig. 3 illustrates an exemplary video decoder 30 for implementing the techniques of the present application, namely performing a fusion candidate list construction of a block to be decoded (current block) and performing decoding of a compressed image based on the constructed fusion candidate list. Video decoder 30 is operative to receive encoded picture data (e.g., an encoded bitstream) 21, e.g., encoded by encoder 20, to obtain a decoded picture 231. During the decoding process, video decoder 30 receives video data, such as an encoded video bitstream representing picture blocks of an encoded video slice and associated syntax elements, from video encoder 20.

In the example of fig. 3, decoder 30 includes entropy decoding unit 304, inverse quantization unit 310, inverse transform processing unit 312, reconstruction unit 314 (e.g., summer 314), buffer 316, loop filter 320, decoded picture buffer 330, and prediction processing unit 360. The prediction processing unit 360 may include an inter prediction unit 344, an intra prediction unit 354, and a mode selection unit 362. In some examples, video decoder 30 may perform a decoding pass that is substantially reciprocal to the encoding pass described with reference to video encoder 20 of fig. 2.

Entropy decoding unit 304 is to perform entropy decoding on encoded picture data 21 to obtain, for example, quantized coefficients 309 and/or decoded encoding parameters (not shown in fig. 3), such as any or all of inter-prediction, intra-prediction parameters, loop filter parameters, and/or other syntax elements (decoded). The entropy decoding unit 304 is further for forwarding the inter-prediction parameters, the intra-prediction parameters, and/or other syntax elements to the prediction processing unit 360. Video decoder 30 may receive syntax elements at the video slice level and/or the video block level.

Inverse quantization unit 310 may be functionally identical to inverse quantization unit 110, inverse transform processing unit 312 may be functionally identical to inverse transform processing unit 212, reconstruction unit 314 may be functionally identical to reconstruction unit 214, buffer 316 may be functionally identical to buffer 216, loop filter 320 may be functionally identical to loop filter 220, and decoded picture buffer 330 may be functionally identical to decoded picture buffer 230.

Prediction processing unit 360 may include inter prediction unit 344 and intra prediction unit 354, where inter prediction unit 344 may be functionally similar to inter prediction unit 244 and intra prediction unit 354 may be functionally similar to intra prediction unit 254. The prediction processing unit 360 is typically used to perform block prediction and/or to obtain a prediction block 365 from the encoded data 21, as well as to receive or obtain (explicitly or implicitly) prediction related parameters and/or information about the selected prediction mode from, for example, the entropy decoding unit 304.

When the video slice is encoded as an intra-coded (I) slice, intra-prediction unit 354 of prediction processing unit 360 is used to generate a prediction block 365 for the picture block of the current video slice based on the signaled intra-prediction mode and data from previously decoded blocks of the current frame or picture. When the video frame is encoded as an inter-coded (i.e., B or P) slice, inter prediction unit 344 (e.g., a motion compensation unit) of prediction processing unit 360 is used to generate a prediction block 365 for the video block of the current video slice based on the motion vectors and other syntax elements received from entropy decoding unit 304. For inter prediction, a prediction block may be generated from one reference picture within one reference picture list. Video decoder 30 may construct the reference frame list using default construction techniques based on the reference pictures stored in DPB 330: list 0 and list 1.

Prediction processing unit 360 is used to determine prediction information for the video blocks of the current video slice by parsing the motion vectors and other syntax elements, and to generate a prediction block for the current video block being decoded using the prediction information. For example, prediction processing unit 360 uses some syntax elements received to determine a prediction mode (e.g., intra or inter prediction) for encoding video blocks of a video slice, an inter prediction slice type (e.g., B-slice, P-slice, or GPB-slice), construction information for one or more of a reference picture list of the slice, a motion vector for each inter-coded video block of the slice, an inter prediction state for each inter-coded video block of the slice, and other information to decode video blocks of the current video slice.

Inverse quantization unit 310 may be used to inverse quantize (i.e., inverse quantize) the quantized transform coefficients provided in the bitstream and decoded by entropy decoding unit 304. The inverse quantization process may include using quantization parameters calculated by video encoder 20 for each video block in the video slice to determine the degree of quantization that should be applied and likewise the degree of inverse quantization that should be applied.

Inverse transform processing unit 312 is used to apply an inverse transform (e.g., an inverse DCT, an inverse integer transform, or a conceptually similar inverse transform process) to the transform coefficients in order to produce a residual block in the pixel domain.

The reconstruction unit 314 (e.g., summer 314) is used to add the inverse transform block 313 (i.e., reconstructed residual block 313) to the prediction block 365 to obtain the reconstructed block 315 in the sample domain, e.g., by adding sample values of the reconstructed residual block 313 to sample values of the prediction block 365.

Loop filter unit 320 (during or after the encoding cycle) is used to filter reconstructed block 315 to obtain filtered block 321 to facilitate pixel transitions or to improve video quality. Loop filter unit 320 is intended to represent one or more loop filters, such as a deblocking filter, a sample-adaptive offset (SAO) filter, or other filters, such as a bilateral filter, an Adaptive Loop Filter (ALF), or a sharpening or smoothing filter, or a collaborative filter. Although loop filter unit 320 is shown in fig. 3 as an in-loop filter, in other configurations, loop filter unit 320 may be implemented as a post-loop filter.

Decoded video block 321 in a given frame or picture is then stored in decoded picture buffer 330, which stores reference pictures for subsequent motion compensation.

Decoder 30 is used to output decoded picture 31, e.g., via output 332, for presentation to or viewing by a user.

Other variations of video decoder 30 may be used to decode the compressed bitstream. For example, decoder 30 may generate an output video stream without loop filter unit 320. For example, the non-transform based decoder 30 may directly inverse quantize the residual signal without the inverse transform processing unit 312 for certain blocks or frames. In another embodiment, video decoder 30 may have inverse quantization unit 310 and inverse transform processing unit 312 combined into a single unit.

Fig. 4 is a schematic structural diagram of a video coding apparatus 400 (e.g., a video encoding apparatus 400 or a video decoding apparatus 400) according to an embodiment of the present invention. Video coding apparatus 400 is suitable for implementing the embodiments described herein. In one embodiment, video coding device 400 may be a video decoder (e.g., video decoder 30 of fig. 1A) or a video encoder (e.g., video encoder 20 of fig. 1A). In another embodiment, video coding device 400 may be one or more components of video decoder 30 of fig. 1A or video encoder 20 of fig. 1A described above.

Video coding apparatus 400 includes: an ingress port 410 and a reception unit (Rx) 420 for receiving data, a processor, logic unit or Central Processing Unit (CPU) 430 for processing data, a transmitter unit (Tx) 440 and an egress port 450 for transmitting data, and a memory 460 for storing data. Video coding device 400 may also include optical-to-electrical conversion components and electrical-to-optical (EO) components coupled with ingress port 410, receiver unit 420, transmitter unit 440, and egress port 450 for egress or ingress of optical or electrical signals.

The processor 430 is implemented by hardware and software. Processor 430 may be implemented as one or more CPU chips, cores (e.g., multi-core processors), FPGAs, ASICs, and DSPs. Processor 430 is in communication with inlet port 410, receiver unit 420, transmitter unit 440, outlet port 450, and memory 460. Processor 430 includes a coding module 470 (e.g., encoding module 470 or decoding module 470). The encoding/decoding module 470 implements the embodiments disclosed above. For example, the encoding/decoding module 470 implements, processes, or provides various encoding operations. Accordingly, substantial improvements are provided to the functionality of the video coding apparatus 400 by the encoding/decoding module 470 and affect the transition of the video coding apparatus 400 to different states. Alternatively, the encode/decode module 470 is implemented as instructions stored in the memory 460 and executed by the processor 430.

The memory 460, which may include one or more disks, tape drives, and solid state drives, may be used as an over-flow data storage device for storing programs when such programs are selectively executed, and for storing instructions and data that are read during program execution. The memory 460 may be volatile and/or nonvolatile, and may be Read Only Memory (ROM), random Access Memory (RAM), random access memory (TCAM), and/or Static Random Access Memory (SRAM).

Fig. 5 is a simplified block diagram of an apparatus 500 that may be used as either or both of source device 12 and destination device 14 in fig. 1A according to an example embodiment. The apparatus 500 may implement the techniques of this application for performing the construction of a fusion candidate list and encoding or decoding an image based on the constructed fusion candidate list. The apparatus 500 may take the form of a computing system including multiple computing devices or a single computing device such as a mobile phone, tablet computer, laptop computer, notebook computer, desktop computer, or the like.

The processor 502 in the apparatus 500 may be a central processor. Alternatively, processor 502 may be any other type of device or devices now or later developed that is capable of manipulating or processing information. As shown, although the disclosed embodiments may be practiced using a single processor, such as processor 502, speed and efficiency advantages may be realized using more than one processor.

In one embodiment, the Memory 504 of the apparatus 500 may be a Read Only Memory (ROM) device or a Random Access Memory (RAM) device. Any other suitable type of storage device may be used for memory 504. The memory 504 may include code and data 506 that is accessed by the processor 502 using the bus 512. The memory 504 may further include an operating system 508 and application programs 510, the application programs 510 including at least one program that permits the processor 502 to perform the methods described herein. For example, applications 510 may include applications 1 through N, with applications 1 through N further including a video encoding application that performs the fusion candidate list construction described herein. The apparatus 500 may also include additional memory in the form of a slave memory 514, the slave memory 514 may be, for example, a memory card for use with a mobile computing device. Because a video communication session may contain a large amount of information, this information may be stored in whole or in part in the slave memory 514 and loaded into the memory 504 for processing as needed.

Device 500 may also include one or more output apparatuses, such as a display 518. In one example, display 518 may be a touch-sensitive display that combines a display and a touch-sensitive element operable to sense touch inputs. A display 518 may be coupled to the processor 502 via the bus 512. Other output devices that permit a user to program apparatus 500 or otherwise use apparatus 500 may be provided in addition to or in lieu of display 518. When the output device is or includes a display, the display may be implemented in different ways, including by a Liquid Crystal Display (LCD), a Cathode Ray Tube (CRT) display, a plasma display, or a Light Emitting Diode (LED) display, such as an Organic LED (OLED) display.

The apparatus 500 may also include or be in communication with an image sensing device 520, the image sensing device 520 being, for example, a camera or any other image sensing device 520 now or later developed that can sense an image, such as an image of a user running the apparatus 500. The image sensing device 520 may be placed directly facing the user running the apparatus 500. In one example, the position and optical axis of image sensing device 520 may be configured such that its field of view includes an area proximate display 518 and display 518 is visible from that area.

The apparatus 500 may also include or be in communication with a sound sensing device 522, such as a microphone or any other sound sensing device now known or later developed that can sense sound in the vicinity of the apparatus 500. The sound sensing device 522 may be positioned to face directly the user operating the apparatus 500 and may be used to receive sounds, such as speech or other utterances, emitted by the user while operating the apparatus 500.

Although the processor 502 and memory 504 of the apparatus 500 are depicted in fig. 5 as being integrated in a single unit, other configurations may also be used. The operations of processor 502 may be distributed among multiple directly couplable machines (each machine having one or more processors), or distributed over a local area or other network. Memory 504 may be distributed among multiple machines, such as a network-based memory or a memory among multiple machines running apparatus 500. Although only a single bus is depicted here, the bus 512 of the device 500 may be formed from multiple buses. Further, the secondary memory 514 may be directly coupled to other components of the apparatus 500 or may be accessible over a network and may comprise a single integrated unit, such as one memory card, or multiple units, such as multiple memory cards. Accordingly, the apparatus 500 may be implemented in a variety of configurations.

Fig. 6 is a flowchart of example operations by which a fusion candidate list construction method in an embodiment of the present invention is implemented in accordance with video encoder 20 and video decoder 30 shown in fig. 1A and 1B. One or more functional units of video encoder 20 or video decoder 30, including prediction processing unit 260/360, may be used to perform the method of fig. 6. In the example of fig. 6, an improved method for constructing a Merge Candidate List is proposed, in the process of adding a Non-adjacent Spatial Merge Candidate (Non-adjacent Spatial Merge Candidate) to the Merge Candidate List (Merge Candidate List), whether to add the Non-adjacent Spatial Merge Candidate to the Merge Candidate List is determined according to an inter-frame prediction mode corresponding to the Non-adjacent Spatial Merge Candidate, so as to improve prediction efficiency.

The method 600 for constructing the candidate list includes:

s601, based on a preset first selection rule, adding motion information of a neighboring block adjacent to a current block space domain into a fusion candidate list of the current block as a space fusion candidate of the current block;

wherein the preset first selection rule includes adding motion information of the neighboring block as a spatial fusion candidate of the current block into a fusion candidate list of the current block when the neighboring block is available and the motion information of the neighboring block is different from motion information of a neighboring block of a specific location; and

s603, based on a preset second selection rule, adding motion information of a non-adjacent block that is not adjacent to the current block spatial domain as a non-adjacent spatial fusion candidate of the current block into the fusion candidate list;

wherein the current block has one or more non-adjacent blocks that are not spatially adjacent, and the preset second selection rule includes: when it is determined that the inter prediction mode of at least one of the non-neighboring blocks is not the predetermined inter prediction mode and the motion information of the at least one non-neighboring block is the same as the motion information of the neighboring block at the specific position or the non-neighboring block if the non-neighboring blocks are available, adding the motion information of the at least one non-neighboring block as a non-neighboring spatial fusion candidate of the current block into the fusion candidate list, and when it is determined that the inter prediction mode of at least one of the non-neighboring blocks is the predetermined inter prediction mode if the non-neighboring blocks are available, not adding the non-neighboring spatial fusion candidate of the at least one non-neighboring block into the fusion candidate list of the current block.

The preset inter-frame prediction mode is a skip/merge mode and/or an Affine (affinity) transformation prediction mode.

It is to be understood that at least one of the non-adjacent blocks in the above-mentioned scheme may be an adjacent block at a predetermined position, that is, the present invention allows some non-adjacent blocks to perform inter prediction mode determination, and certainly allows all non-adjacent blocks to perform inter prediction mode determination.

Because the number of the non-adjacent space fusion candidates is large, and the length of the fusion candidate list is small, the fusion candidates are properly screened in the process of adding the fusion candidates into the fusion candidate list, so that the diversity of the fusion candidates in the fusion candidate list and the similarity between the fusion candidates and the motion information of the current block can be improved, and the prediction efficiency is improved. However, in the prior art, whether to add a non-adjacent spatial fusion candidate into the fusion candidate list is determined according to whether the non-adjacent spatial fusion candidate is repeated with an existing fusion candidate in the fusion candidate list, but the inter-frame prediction mode corresponding to the non-adjacent spatial fusion candidate is not considered. The motion information of the non-adjacent space fusion candidate using the skip/merge mode is easily repeated or similar to the motion information of the adjacent space fusion candidate, which is not beneficial to improving the diversity of the motion information in the fusion candidate list. In addition, if the non-adjacent spatial fusion candidate uses the affine model prediction mode and the current block uses the translational model prediction mode, the two regions have different motion types, so that the correlation between the non-adjacent spatial fusion candidate and the actual motion information of the current block is low, and the fusion candidate list should not be added. In the invention, the inter-frame prediction mode of the non-adjacent block is used as a judgment standard in the process of acquiring the non-adjacent space fusion candidate, so that the diversity of motion information in the fusion candidate list can be effectively improved, and the fusion candidate with low relevance can be prevented from being added into the fusion candidate list, thereby effectively improving the performance of coding and decoding. It should be noted that the preset inter prediction mode may also be other modes except the skip mode/blend mode or the Affine mode mentioned in the present invention, such as an optical flow field mode, etc.

Optionally, before the step S603, the method for constructing a candidate list of the present invention may further include the steps of:

s602 adds the motion information of the neighboring block at the bottom right corner of the collocated block in the reference frame of the current block as the temporal fusion candidate of the current block into the fusion candidate list, wherein the position of the collocated block in the reference frame is the same as the position of the current block in the current frame, or adds the motion information of the center point of the collocated block as the temporal fusion candidate of the current block into the fusion candidate list under the condition that the motion information of the neighboring block at the bottom right corner of the collocated block is unavailable.

The method comprises the step of inheriting the acquisition step of a time-domain fusion candidate in HEVC, wherein the step utilizes the characteristic that a block (a co-located block) at the same position in a reference frame of a current block in the time domain is decoded, and motion information adjacent to the lower right corner of the co-located block is used as a time-domain fusion candidate of the current block and is added into a fusion candidate list so as to enrich the diversity of the fusion candidate list. It should be noted that the time domain fusion candidates may also be obtained by selecting blocks at other adjacent or non-adjacent positions adjacent to the co-located block according to the requirement, which may be combined with the present invention as a further extension or alternative of the above steps.

Optionally, after the step S603, the method for constructing a candidate list according to the present invention may further include the following steps

S605 adding a bidirectional prediction fusion candidate to the fusion candidate list when the current block belongs to a bidirectional prediction slice (bi-predictive slice), or adding a zero motion vector fusion candidate to the fusion candidate list if the number of the fusion candidates in the fusion candidate list does not reach the predetermined value after the bidirectional prediction fusion candidate is added to the fusion candidate list; or adding a zero motion vector fusion candidate to the fusion candidate list when the current block belongs to a uni-predictive slice (uni-predictive slice).

As mentioned above, the fusion candidate list is usually a fusion candidate with a predetermined number, but may occur in individual cases, after going through the above steps S601-S603, the fusion candidate list is still not filled, i.e. there is still room for other fusion candidates, in order to fully utilize the coding space provided by the fusion candidate list, the fusion candidate list may be filled according to the prediction type of the current block, wherein a bidirectional prediction fusion candidate is added to the fusion candidate list when the current block belongs to a bidirectional prediction slice (bi-predictive slice), or a zero motion vector fusion candidate is added to the fusion candidate list when the number of the fusion candidates in the fusion candidate list does not reach the predetermined value after the bidirectional prediction fusion candidate is added to the fusion candidate list; or adding a zero motion vector fusion candidate to the fusion candidate list when the current block belongs to a uni-predictive slice (uni-predictive slice).

The scheme of the invention judges whether to add the non-adjacent space fusion candidate into the fusion candidate list according to the inter-frame prediction mode of the non-adjacent space fusion candidate, thereby ensuring that the added non-adjacent space fusion candidate is more accurate and diversified and improving the coding efficiency. The following is a specific example of performing fusion candidate list construction based on the present invention.

Assuming that the length of the fusion candidate list is N, which is a preset value, that is, the number of fusion candidates included in the fusion candidate list after the construction is completed is N, for example, N =5, 6, 8, 10, and so on. Specifically, in one embodiment, the method for constructing the fusion candidate list includes the following steps;

step 1: and adding the spatial fusion candidate spatially adjacent to the current block into the fusion candidate list of the current block.

This step is a prior art method, such as HEVC, that takes spatial fusion candidates and adds them to the fusion candidate list. The spatially adjacent spatial fusion candidates are the motion information of the A, B, C, D, E block in fig. 9, and their order of addition to the fusion candidate list is A, B, C, D, E.

Assuming that the coordinates of the top left corner of the current block are P0= (x 0, y 0), the width and height of the current block are W and H, respectively, and the size of the spatially adjacent A, B, C, D, E block is 4x4, then the coordinates of the top left corner of the a block are PA = (x 0-4, y0+ H-4); the coordinate of the upper left corner of the B block is PB = (x 0+ W-4, y0-4); the coordinate of the upper left corner of the C block is PC = (x 0+ W, y 0-4); the coordinate of the upper left corner of block D is PD = (x 0-4, y0+ H); the coordinates of the upper left corner of the E block are PE = (x 0-4, y0-4). In general, motion information is stored in units of 4 × 4 blocks in a motion vector field, and the motion information of a block can be found from the coordinates of the upper left corner of the block in the motion vector field. E.g. the coordinate of the upper left corner of the block is (x, y), then the coordinate of its corresponding element in the motion vector field is (x, y)>>2,y>>2)，“>>"indicates a shift right operation. After the coordinates of the top left corner of a spatial neighboring block and its corresponding element coordinates in motion vector length are obtained, the motion information of the corresponding spatial neighboring block, such as blocks a-E, or motion vector information of blocks a-E, also referred to as spatial fusion candidates, including but not limited to whether one or two reference picture lists are used and the information of the reference index and motion vector of each list, is found, and the first candidate in the fusion candidate list is spatial neighboring block a. In the existing HEVC standard, according to fig. 9, at most four spatial fusion candidates can be inserted in the merge list in that order by sequentially checking A, B, C, D and E in turn. The maximum number of spatial fusion candidates allowed in VVC may be other than four, may be more, and may of course be less, depending on the complexity of the algorithm and the gains that can be brought about by different numbers of spatial fusion candidates. Some additional redundancy checks are performed before all motion information of neighboring blocks are candidates for fusion. These redundancy checks can be divided into two categories for two different purposes: a. avoiding the presence of candidates with redundant motion information in the list; b. preventing merging of two otherwise representable partitions that would generate redundant syntax. When M is the number of spatial fusion candidates, the complete redundancy check will be performed by

And comparing the secondary motion information. In the case of five potential spatial fusion candidates, ten motion information comparisons would be required to ensure that all candidates in the merge list have different motion information. To simplify the algorithm, the check for redundant motion information has been reduced to a subset, thereby maintaining coding efficiency while significantly reducing comparison logic. In the final design, no more than two comparisons are performed for each candidate, resulting in a total of five comparisons. Given the order of { A, B, C, D, E }, the motion information in the C block is compared only to the motion information in the B block, the motion information in the D block is compared only to the motion information in the A block, and the motion information in the E block is compared only to the motion information in the A and B blocks. Furthermore, a fusion Estimation hierarchy is introduced in HEVC, in which a fusion candidate list can be independently obtained by checking whether a block containing a fusion candidate is located in a Merge Estimation Region (MER), that is, a fusion candidate in the same MER cannot be included in the fusion candidate list, thereby allowing a plurality of image blocks to be processed to perform motion Estimation in a fusion mode in parallel for corresponding inter prediction.

Step 2: and adding the time domain fusion candidate of the current block into a fusion candidate list of the current block.

This step is an optional step, i.e. it can be performed or not according to the requirement choice, in HEVC, (Sps/slice _ temporal _ mvp _ enabled _ flag) controls the enabling or disabling of TMVP at the sequence level or picture level. The time domain fusion candidate of the current block is usually obtained from the motion information of the image block at the lower right corner of the image block at the same position as the current block in the reference image of the current block, and if the image block is unavailable, the motion information of the central position of the image block at the same position as the current block in the reference image of the current block is obtained. In particular, see, for example, recommendation ITU-T H.265. International Standard ISO/IEC 23008-2 representations an evaluation of the existing video coding recommendations,8.5.3.2derivation processes for motion vector components and reference indices.

And step 3: and adding the non-adjacent space fusion candidate into the fusion candidate list of the current block according to the inter-frame prediction mode of the non-adjacent space fusion candidate of the current block.

The non-adjacent spatial fusion candidates of the current block may be constructed in various manners, and the present invention is not limited thereto. For example, the non-adjacent spatial fusion candidates are the motion information of A1, B1, C1, D1, E1, A2, B2, C2, D2, E2, F, G, H, I block in fig. 9; the order in which non-adjacent spatial fusion candidates join the fusion candidate list is A1, B1, C1, D1, E1, F, G, H, I, A, B2, C2, D2, E2. For example, in the motion information of A1, B1, C1, D1, E1, A2, B2, C2, D2, E2 block in fig. 1, the order of adding the non-neighboring spatial fusion candidates to the fusion candidate list is A1, B1, C1, D1, E1, A2, B2, C2, D2, E2.

Note that the coordinates of the top left corner of the current block are P0= (x 0, y 0), and the width and height of the current block are W and H, respectively, so that the coordinates of the top left corner of the Ai block (i =1 or 2) are PAi = (x 0-4-i × Sx, y0+ H-4); the coordinates of the upper left corner of the Bi block are PBi = (x 0+ W-4, y0-4-i = (Sy)); the upper left corner coordinates of Ci blocks are PCi = (x 0+ W, y0-4-i Sy); the coordinates of the top left corner of the Di block are PDi = (x 0-4-i Sx, y0+ H); the upper left-hand coordinates of the Ei block are PEi = (x 0-4-i Sx, y0-4-i Sy).

The inter prediction mode of the non-adjacent spatial fusion candidate is an inter prediction mode of a coding unit to which the non-adjacent spatial fusion candidate belongs, or an inter prediction mode of a prediction unit to which the non-adjacent spatial fusion candidate belongs. If the CU corresponding to the non-neighboring spatial fusion candidate is unavailable (e.g., the CU corresponding to the non-neighboring spatial fusion candidate is not in the current slice or has not completed reconstruction), or the CU corresponding to the non-neighboring spatial fusion candidate is available but does not use the inter prediction mode, then the non-neighboring spatial fusion candidate is unavailable. The unavailable non-adjacent spatial fusion candidates do not join the fusion candidate list, which is the prior art, and reference may be specifically made to relevant sections in the existing HEVC standard.

The process of adding an available non-adjacent spatial fusion candidate to the fusion candidate list of the current block according to its inter prediction mode may include one of the following processes:

the method comprises the following steps: if the interframe prediction mode of the non-adjacent space fusion candidate is the skip/merge mode, not adding the non-adjacent space fusion candidate into the fusion candidate list; otherwise, judging whether the motion information of the non-adjacent space fusion candidate is different from the motion information of the fusion candidate at the preset position or is different from the motion information of the existing fusion candidate in the fusion candidate list, and if the judgment is true, namely if the judgment is different, adding the non-adjacent space fusion candidate into the fusion candidate list. The determination of whether two pieces of motion information are different may be determined according to whether any one of prediction directions, reference frames, and motion vectors of the two pieces of motion information is the same, and if any one of the parameters is different, the two pieces of motion information are considered to be different.

The second method comprises the following steps: if the inter-frame prediction mode of the non-adjacent space fusion candidate is the affine transformation prediction mode, not adding the non-adjacent space fusion candidate into the fusion candidate list; otherwise, judging whether the motion information of the non-adjacent space fusion candidate is different from the motion information of the fusion candidate at the specific position or is different from the motion information of the existing fusion candidate in the fusion candidate list, if the judgment is true, namely, if the judgment is different, adding the non-adjacent space fusion candidate into the fusion candidate list.

The third method comprises the following steps: if the inter-frame prediction mode of the non-adjacent space fusion candidate is a skip/merge mode or an affine transformation prediction mode, not adding the non-adjacent space fusion candidate into a fusion candidate list; otherwise, judging whether the motion information of the non-adjacent space fusion candidate is different from the motion information of the fusion candidate at the preset position or is different from the motion information of the existing fusion candidate in the fusion candidate list, if the judgment is true, and if the judgment is not true, adding the non-adjacent space fusion candidate into the fusion candidate list.

The method comprises the following steps: if the inter-prediction mode of the non-adjacent spatial fusion candidate is skip/merge mode and the non-adjacent spatial fusion candidate is located in A2, B2, C2, D2, E2 block, not adding the non-adjacent spatial fusion candidate to the fusion candidate list; otherwise, judging whether the motion information of the non-adjacent space fusion candidate is different from the motion information of the fusion candidate at the preset position or is different from the motion information of the existing fusion candidate in the fusion candidate list, if the judgment is true, and if the judgment is not true, adding the non-adjacent space fusion candidate into the fusion candidate list.

The method five comprises the following steps: if the inter-frame prediction mode of the non-adjacent spatial fusion candidate is skip/merge mode and the non-adjacent spatial fusion candidate is located in a specific coding block, wherein the specific block comprises A1, B1, C2, D2 and E2 blocks, the non-adjacent spatial fusion candidate is not added into the fusion candidate list; otherwise, judging whether the motion information of the non-adjacent space fusion candidate is different from the motion information of the fusion candidate at the preset position or not, or is different from the motion information of the existing fusion candidate in the fusion candidate list, if the judgment is true, and if the judgment is not true, adding the non-adjacent space fusion candidate into the fusion candidate list.

The method six: if the inter-prediction mode of the non-adjacent spatial fusion candidate is an affine transformation mode and the non-adjacent spatial fusion candidate is located within the A2, B2, C2, D2, E2 block, not adding this non-adjacent spatial fusion candidate to the fusion candidate list; otherwise, judging whether the motion information of the non-adjacent space fusion candidate is different from the motion information of the fusion candidate at the preset position or not, or judging whether the motion information of the non-adjacent space fusion candidate is different from the motion information of at least one fusion candidate existing in the fusion candidate list, if the judgment is true, and if the judgment is not true, adding the non-adjacent space fusion candidate into the fusion candidate list.

The method comprises the following steps: if the inter-prediction mode of the non-adjacent spatial fusion candidate is an affine transformation mode and the non-adjacent spatial fusion candidate is located within the A1, B1, C1, D1, E1 block, not adding this non-adjacent spatial fusion candidate to the fusion candidate list; otherwise, judging whether the motion information of the non-adjacent space fusion candidate is different from the motion information of the fusion candidate at the preset position or not, or judging whether the motion information of the non-adjacent space fusion candidate is different from the motion information of at least one fusion candidate existing in the fusion candidate list, if the judgment is true, and if the judgment is not true, adding the non-adjacent space fusion candidate into the fusion candidate list.

This step is an optional step, such as the method in HEVC that takes bi-predictive fusion candidates and zero motion vector fusion candidates and adds them to the fusion candidate list.

When the current block is decoded, if the current block uses a skip/merge mode, the merge index is analyzed from the code stream, and the merge candidate corresponding to the merge index is selected from the merge candidate list constructed by the method, so that the motion information of the current block is obtained. And performing motion compensation according to the motion information of the current block to obtain a predicted image of the current block. And adding the predicted image of the current block and the residual image of the current block to obtain a reconstructed image of the current block, thereby finishing the decoding of the current block.

Compared with the prior art, the scheme of the invention judges whether to add the non-adjacent space fusion candidate into the fusion candidate list according to the inter-frame prediction mode of the non-adjacent space fusion candidate, so that the added non-adjacent space fusion candidate is more accurate and diversified, and the coding efficiency can be improved.

Fig. 7 is a flowchart of example operations of image encoding by video decoder 30 according to fig. 1A and 1B implementing the fusion candidate list construction method of fig. 6 in an embodiment of the present invention. One or more functional units of video decoder 30, including prediction processing unit 360, may be used to perform the method of fig. 7. In the example of fig. 7, the decoding of the picture is performed based on the fusion candidate list constructed by the method of fig. 6, and the decoding method 700 specifically includes:

s701, analyzing the code stream to obtain a fusion candidate index;

s703, acquiring a corresponding fusion candidate from the fusion candidate list according to the fusion candidate index, and taking the fusion candidate as the motion information of the current block;

please refer to fig. 6 and the corresponding text for the method for constructing the fusion candidate list.

S705, performing inter-frame prediction on the current block according to the motion information of the current block to obtain a predicted image of the current block;

s707, obtaining a residual error image of the current block;

s709, adding the prediction image of the current block and the residual image of the current block to obtain a reconstructed image of the current block.

Before the step S701 or after the step S701 and before the step S703, the decoding method 700 further includes; and constructing a fusion candidate rule list of the current block according to the method in fig. 6.

Compared with the prior art, the decoding method adopts the fusion candidate list construction method for judging whether to add the non-adjacent space fusion candidate into the fusion candidate list according to the inter-frame prediction mode of the non-adjacent space fusion candidate, so that the added non-adjacent space fusion candidate is more accurate and diversified, and the decoding efficiency can be improved.

Fig. 8 is a flowchart of example operations of image encoding by video encoder 20 of fig. 1A and 1B implementing the fusion candidate list construction method of fig. 6 in an embodiment of the present invention. One or more functional units of video encoder 20, including prediction processing unit 260, may be configured to perform the method of fig. 8. In the example of fig. 8, the encoding of the picture is performed based on the fusion candidate list constructed by the method of fig. 6, and the decoding method 800 specifically includes:

s801 performing RDO-based fusion evaluation (Merge evaluation) on the current block based on each fusion candidate in the fusion candidate list and using a fusion candidate with a minimum rate distortion cost value as motion information of the current block;

S803, encoding the current block based on the motion information of the current block to form encoded data;

s805 appends the position index of the fusion candidate with the smallest rate-distortion cost value in the fusion candidate list to the encoded data.

Before the step S801 or after the step S801 and before the step S803, the decoding method 800 further includes; and constructing a fusion candidate rule list of the current block according to the method in fig. 6.

Compared with the prior art, the encoding method adopts the fusion candidate list construction method which judges whether to add the non-adjacent space fusion candidates into the fusion candidate list according to the inter-frame prediction mode of the non-adjacent space fusion candidates, so that the added non-adjacent space fusion candidates are more accurate and diversified, and the decoding efficiency can be improved.

The embodiment of the present application provides a device for constructing a fusion candidate sporter list for inter-frame prediction, where the device may be a video decoder, a video encoder, or a decoder. Specifically, the construction device of the fusion candidate athlete list is configured to perform the steps performed by the construction device in the above construction method of the fusion candidate athlete list. The building device provided by the embodiment of the application can comprise modules corresponding to the corresponding steps.

In the embodiment of the present application, the building apparatus for fusing candidate athlete lists may perform functional module division according to the above method, for example, each functional module may be divided corresponding to each function, or two or more functions may be integrated into one processing module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The division of the modules in the embodiment of the present application is schematic, and is only one logic function division, and there may be another division manner in actual implementation.

Fig. 11 is a schematic diagram showing a possible structure of the fusion candidate moving picture list constructing apparatus for inter-frame prediction according to the above embodiment, in a case where each functional module is divided according to each function. As shown in fig. 11, the fusion candidate actor list constructing apparatus 1100 includes a spatial domain neighboring fusion candidate obtaining module 1101, a spatial domain non-neighboring fusion candidate obtaining module 1103, and an optional temporal domain fusion candidate obtaining module 1105 and an extended fusion candidate obtaining module 1107.

A spatial neighboring fusion candidate obtaining module 1101, configured to add, to a fusion candidate list of a current block, motion information of a neighboring block spatially adjacent to the current block as a spatial fusion candidate of the current block based on a preset first selection rule, where the preset first selection rule includes adding, when the neighboring block is available and the motion information of the neighboring block is different from the motion information of a neighboring block at a specific position, the motion information of the neighboring block as a spatial fusion candidate of the current block to the fusion candidate list of the current block;

a spatial non-adjacent fusion candidate obtaining module 1103, configured to add, to the fusion candidate list, motion information of a non-adjacent block that is not spatially adjacent to the current block as a non-adjacent spatial fusion candidate for the current block based on a preset second selection rule, where the current block has one or more non-adjacent blocks that are not spatially adjacent to each other, and the preset second selection rule includes: when it is determined that the inter prediction mode of at least one of the non-neighboring blocks is not the predetermined inter prediction mode and the motion information of the at least one non-neighboring block is the same as the motion information of the neighboring block at the specific position or the non-neighboring block if the non-neighboring blocks are available, adding the motion information of the at least one non-neighboring block as a non-neighboring spatial fusion candidate of the current block into the fusion candidate list, and when it is determined that the inter prediction mode of at least one of the non-neighboring blocks is the predetermined inter prediction mode if the non-neighboring blocks are available, not adding the non-neighboring spatial fusion candidate of the at least one non-neighboring block into the fusion candidate list of the current block.

Optionally, the temporal fusion candidate obtaining module 1105 is configured to add the motion information of the neighboring block at the bottom-right corner of the collocated block at the same position in the reference frame of the current block into the fusion candidate list as a temporal fusion candidate of the current block, or add the motion information of the center point of the collocated block into the fusion candidate list as a temporal fusion candidate of the current block under the condition that the motion information of the neighboring block at the bottom-right corner of the collocated block is unavailable.

Optionally, the extended fusion candidate obtaining module 1107 adds a bidirectional prediction fusion candidate to the fusion candidate list when the current block belongs to a bidirectional prediction slice (bi-predictive slice), or adds a zero motion vector fusion candidate to the fusion candidate list when the number of the fusion candidates in the fusion candidate list does not reach the predetermined value after the bidirectional prediction fusion candidate is added to the fusion candidate list; or adding a zero motion vector fusion candidate to the fusion candidate list when the current block belongs to a uni-predictive slice (uni-predictive slice).

The invention also provides a decoding device which can be a video decoder. Specifically, the decoding apparatus is configured to perform the decoding method described in fig. 7. The decoding device provided by the embodiment of the application can comprise modules corresponding to the corresponding steps.

The embodiment of the present application may perform the division of the function modules on the construction apparatus for fusing the candidate athlete list according to the method example, for example, each function module may be divided corresponding to each function, or two or more functions may be integrated into one processing module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The division of the modules in the embodiment of the present application is schematic, and is only a logic function division, and there may be another division manner in actual implementation.

In the case of dividing each functional module in correspondence with each function, fig. 12 shows a schematic configuration diagram of the encoding device according to the above-described embodiment. As shown in fig. 12, the encoding apparatus 1200 includes: the fusion candidate athlete list constructing device 1201, the code stream parsing module 1203, the motion information obtaining module 1205, the predicting module 1207, the residual error obtaining module 1209, and the reconstructing module 1211.

A fusion candidate actor list constructing device 1201 having the same function as the fusion candidate actor list constructing device 1100 in fig. 11, and configured to construct a fusion candidate list of the current block;

a code stream parsing module 1203, configured to parse the code stream to obtain a fusion candidate index;

a motion information obtaining module 1205, configured to obtain, according to the fusion candidate index, a corresponding fusion candidate from the fusion candidate list, and use the fusion candidate as the motion information of the current block;

the prediction module 1207 is configured to perform inter-frame prediction on the current block according to the motion information of the current block to obtain a prediction image of the current block;

a residual error obtaining module 1209, configured to obtain a residual error image of the current block;

a reconstructing module 1207, configured to add the predicted image of the current block and the residual image of the current block to obtain a reconstructed image of the current block.

The invention also provides a coding device which can be a video coder. Specifically, the decoding apparatus is configured to perform the decoding method described in fig. 8. The encoding device provided by the embodiment of the application may include modules corresponding to the corresponding steps.

In the embodiment of the present application, the building apparatus for fusing candidate athlete lists may perform functional module division according to the above method, for example, each functional module may be divided corresponding to each function, or two or more functions may be integrated into one processing module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The division of the modules in the embodiment of the present application is schematic, and is only a logic function division, and there may be another division manner in actual implementation.

In the case of dividing each functional module in correspondence with each function, fig. 13 shows a schematic configuration diagram of the encoding device according to the above-described embodiment. As shown in fig. 13, the encoding apparatus 1300 includes: a fusion candidate sporter list construction means 1301, a motion information determination module 1303, a prediction encoding module 1305, and a fusion candidate index encoding module 1307.

A fusion candidate athlete list constructing apparatus 1301 having the same function as the fusion candidate athlete list constructing apparatus 1100 in fig. 11, and configured to construct a fusion candidate athlete list of a current block;

a motion information determining module 1303, configured to perform RDO-based fusion evaluation (Merge evaluation) on the current block based on each fusion candidate in the fusion candidate list and take the fusion candidate with the smallest rate-distortion cost value as the motion information of the current block;

a prediction encoding module 1305, configured to encode the current block based on the motion information of the current block to form encoded data; and;

the fusion candidate index coding module 1307 appends the position index of the fusion candidate with the smallest rate-distortion cost value in the fusion candidate list to the coded data.

The inventive arrangements may also be implemented in the form of a processor, i.e., a memory having stored therein a set of executable instructions, which may be executed by a digital processor to implement any of the methods shown in fig. 6-8. As shown in fig. 14 in particular, the apparatus shown in fig. 14 may be used as a decoding apparatus 1400, an encoding apparatus 1500, or a fusion candidate list construction apparatus 1600 for inter prediction.

When used as the decoding apparatus 1400, it comprises a digital processor 1401 and a memory 1403, in which is stored an executable instruction set, the digital processor reading the instruction set stored in the memory for implementing the decoding method described in figure 7.

When used as the encoding apparatus 1500, it comprises a digital processor 1501 and a memory 1503 in which is stored a set of executable instructions, the digital processor reading the set of instructions stored in the memory for implementing the decoding method described in fig. 7.

When used as the fusion candidate list construction apparatus 1600 for inter-prediction, it comprises a digital processor 1601 in which is stored an executable instruction set, and a memory 1603 in which the digital processor reads the instruction set stored in the memory for implementing the decoding method described in fig. 6. In one or more examples, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. Computer readable media may comprise computer readable storage media corresponding to tangible media, such as data storage media or communication media, including any medium that facilitates transfer of a computer program from one place to another, such as according to a communication protocol. In this manner, the computer-readable medium may generally correspond to (1) a non-transitory tangible computer-readable storage medium, or (2) a communication medium, e.g., a signal or carrier wave. A data storage medium may be any available medium that can be accessed by one or more computers or one or more processors to retrieve instructions, code and/or data structures for implementing the techniques described in this disclosure. The computer program product may include a computer-readable medium.

By way of example, and not limitation, such computer-readable storage media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, any connection is properly termed a computer-readable medium. For example, if instructions are transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital Subscriber Line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. It should be understood, however, that the computer-readable storage media and data storage media do not include connections, carrier waves, signals, or other transitory media, but are instead directed to non-transitory tangible storage media. Disk and disc, as used herein, includes Compact Disc (CD), laser disc, optical disc, digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

The instructions may be executed by one or more processors, such as one or more Digital Signal Processors (DSPs), general purpose microprocessors, application Specific Integrated Circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuitry. Accordingly, the term "processor," as used herein may refer to any of the foregoing structure or any other structure suitable for implementation of the techniques described herein. In addition, in some aspects, the functionality described herein may be provided within dedicated hardware and/or software modules for encoding and decoding, or incorporated in a composite codec. Also, the techniques may be fully implemented in one or more circuits or logic elements.

The techniques of this disclosure may be implemented in a variety of devices or apparatuses including a wireless handset, an Integrated Circuit (IC), or a collection of ICs (e.g., a chipset). This disclosure describes various components, modules, or units to emphasize functional aspects of apparatus for performing the disclosed techniques, but does not necessarily require realization by different hardware units. Specifically, as described above, the various units may be combined in a codec hardware unit, or provided by a collection of interoperative hardware units, including one or more processors as described above, in conjunction with suitable software and/or firmware.

Claims

1. A method for constructing a fusion candidate list for inter-frame prediction, comprising:

adding motion information of a neighboring block spatially adjacent to a current block as a spatial fusion candidate of the current block into a fusion candidate list of the current block based on a preset first selection rule, wherein the preset first selection rule includes adding the motion information of the neighboring block as the spatial fusion candidate of the current block into the fusion candidate list of the current block when the neighboring block is available and the motion information of the neighboring block is different from the motion information of a neighboring block at a specific position;

adding motion information of a non-neighboring block spatially non-adjacent to the current block as a non-neighboring spatial fusion candidate of the current block into the fusion candidate list based on a preset second selection rule, wherein the current block has one or more spatially non-adjacent non-neighboring blocks, and the preset second selection rule includes: when it is determined that the inter prediction mode of at least one of the non-neighboring blocks is not the predetermined inter prediction mode and the motion information of the at least one non-neighboring block is the same as the motion information of a neighboring block at a specific position or a non-neighboring block if the non-neighboring blocks are available, adding the motion information of the at least one non-neighboring block as a non-neighboring spatial fusion candidate of the current block into the fusion candidate list, and when it is determined that the inter prediction mode of at least one of the non-neighboring blocks is the predetermined inter prediction mode if the non-neighboring blocks are available, not adding the non-neighboring spatial fusion candidate of the at least one non-neighboring block into the fusion candidate list of the current block.

2. The method of claim 1, wherein before the adding motion information of a non-neighboring block that is not spatially adjacent to the current block as a non-neighboring spatial fusion candidate of the current block to the fusion candidate list of the current block based on a preset second selection rule, the method further comprises:

and adding the motion information of a lower-right adjacent block of a collocated block in a reference frame of the current block into the fusion candidate list as a temporal fusion candidate of the current block, wherein the position of the collocated block in the reference frame is the same as that of the current block in the current frame, or adding the motion information of the center point of the collocated block into the fusion candidate list as a temporal fusion candidate of the current block under the condition that the motion information of the lower-right adjacent block of the collocated block is unavailable.

3. The method of claim 1, wherein after adding motion information of a non-neighboring block that is not spatially adjacent to the current block as a non-neighboring spatial fusion candidate for the current block to a fusion candidate list for the current block based on a preset second selection rule, and a number of the fusion candidates in the fusion candidate list does not reach a predetermined value, the method further comprises: adding a bidirectional prediction fusion candidate to the fusion candidate list when the current block belongs to a bidirectional prediction slice (bi-predictive slice), or adding a zero motion vector fusion candidate to the fusion candidate list if the number of the fusion candidates in the fusion candidate list does not reach the predetermined value after the bidirectional prediction fusion candidate is added to the fusion candidate list; or adding a zero motion vector fusion candidate to the fusion candidate list when the current block belongs to a uni-predictive slice (uni-predictive slice).

4. The method of claim 1, wherein the predetermined inter prediction mode is a skip/merge mode (skip/merge mode).

5. The method of claim 1, wherein the predetermined inter prediction mode is an Affine (Affine) transform prediction mode.

6. The method of claim 1, wherein the predetermined inter prediction modes are a skip/merge mode and an Affine (Affine) transform prediction mode.

7. A decoding method, wherein the fusion candidate list constructed according to any one of claims 1 to 6 is applied to a decoding process of a current block, and the decoding process comprises:

constructing a fusion candidate list of the current block according to the method of any one of claims 1 to 6;

analyzing the code stream to obtain a fusion candidate index;

acquiring a corresponding fusion candidate from the fusion candidate list according to the fusion candidate index and taking the fusion candidate as the motion information of the current block;

performing inter-frame prediction on the current block according to the motion information of the current block to obtain a predicted image of the current block;

acquiring a residual error image of the current block;

and adding the predicted image of the current block and the residual image of the current block to obtain a reconstructed image of the current block.

8. An encoding method, wherein the fusion candidate list constructed according to any one of claims 1 to 6 is applied to an encoding process of a current block, and the encoding process comprises:

constructing a fusion candidate list of the current block according to the method of any one of claims 1 to 6; performing RDO-based fusion evaluation (Merge evaluation) on the current block based on each fusion candidate in the fusion candidate list and taking the fusion candidate with the minimum rate-distortion cost value as the motion information of the current block;

encoding the current block based on the motion information of the current block to form encoded data;

and adding the position index of the fusion candidate with the minimum rate distortion cost value in the fusion candidate list to the coded data.

9. A fusion candidate list construction apparatus for inter prediction, comprising:

a spatial domain neighbor fusion candidate obtaining module, configured to add, based on a preset first selection rule, motion information of a neighboring block spatially adjacent to a current block as a spatial fusion candidate of the current block into a fusion candidate list of the current block, where the preset first selection rule includes adding, when the neighboring block is available and the motion information of the neighboring block is different from the motion information of a neighboring block at a specific position, the motion information of the neighboring block as a spatial fusion candidate of the current block into the fusion candidate list of the current block;

a spatial non-adjacent fusion candidate obtaining module, configured to add, to the fusion candidate list, motion information of a non-adjacent block that is not spatially adjacent to the current block as a non-adjacent spatial fusion candidate for the current block based on a preset second selection rule, where the current block has one or more non-adjacent blocks that are not spatially adjacent to each other, and the preset second selection rule includes: when it is determined that the inter prediction mode of at least one of the non-neighboring blocks is not the predetermined inter prediction mode and the motion information of the at least one non-neighboring block is the same as the motion information of the neighboring block at the specific position or the non-neighboring block if the non-neighboring blocks are available, adding the motion information of the at least one non-neighboring block as a non-neighboring spatial fusion candidate of the current block into the fusion candidate list, and when it is determined that the inter prediction mode of at least one of the non-neighboring blocks is the predetermined inter prediction mode if the non-neighboring blocks are available, not adding the non-neighboring spatial fusion candidate of the at least one non-neighboring block into the fusion candidate list of the current block.

10. The apparatus of claim 9, wherein the apparatus further comprises:

a temporal fusion candidate obtaining module, configured to add the motion information of the lower-right neighboring block of the current block at the same position in the reference frame as a temporal fusion candidate of the current block to the fusion candidate list, or add the motion information of the center point of the collocated block as a temporal fusion candidate of the current block to the fusion candidate list under the condition that the motion information of the lower-right neighboring block of the collocated block is unavailable.

11. The apparatus of claim 9, wherein the apparatus further comprises:

an extended fusion candidate obtaining module, configured to add a bidirectional prediction fusion candidate to the fusion candidate list when the current block belongs to a bidirectional prediction slice (bi-predictive slice), or add a zero motion vector fusion candidate to the fusion candidate list if the number of the fusion candidates in the fusion candidate list does not reach a predetermined value after the bidirectional prediction fusion candidate is added to the fusion candidate list; or adding a zero motion vector fusion candidate to the fusion candidate list when the current block belongs to a uni-predictive slice (uni-predictive slice).

12. The apparatus of claim 9, wherein the predetermined inter prediction mode is a skip/merge mode (skip/merge mode).

13. The apparatus of claim 9, wherein the predetermined inter prediction mode is an Affine (Affine) transform prediction mode.

14. The apparatus of claim 9, wherein the predetermined inter prediction mode is a skip/merge mode or an Affine (Affine) transform prediction mode.

15. A decoding apparatus, wherein the fusion candidate list construction apparatus for inter prediction according to any one of claims 9 to 14 is applied to the decoding apparatus for decoding a current block, the decoding apparatus comprising:

the fusion candidate list construction apparatus for inter prediction according to any of claims 9-14, configured to construct a fusion candidate list of a current block;

the code stream analyzing module is used for analyzing the code stream to obtain a fusion candidate index;

a motion information obtaining module, configured to obtain a corresponding fusion candidate from the fusion candidate list according to the fusion candidate index, and use the fusion candidate as the motion information of the current block;

the prediction module is used for carrying out inter-frame prediction on the current block according to the motion information of the current block to obtain a predicted image of the current block;

a residual error obtaining module, configured to obtain a residual error image of the current block;

and the reconstruction module is used for adding the predicted image of the current block and the residual image of the current block to obtain a reconstructed image of the current block.

16. An encoding apparatus to which the fusion candidate list construction apparatus for inter prediction according to any one of claims 9 to 14 is applied to encode a current block, the encoding apparatus comprising:

the fusion candidate list construction apparatus for inter prediction according to any of claims 9 to 14, configured to construct a fusion candidate list of a current block; a motion information determination module, configured to perform RDO-based fusion evaluation (Merge evaluation) on the current block based on each fusion candidate in the fusion candidate list and take the fusion candidate with the smallest rate distortion cost value as motion information of the current block;

the prediction coding module is used for coding the current block based on the motion information of the current block to form coded data; and;

and a fusion candidate index encoding module for adding the position index of the fusion candidate with the minimum rate distortion cost value in the fusion candidate list to the encoded data.

17. Decoding apparatus comprising a digital processor and a memory having stored therein a set of executable instructions, the digital processor reading the set of instructions stored in the memory for implementing a decoding method as claimed in claim 7.

18. An encoding apparatus comprising a digital processor and a memory having stored therein a set of executable instructions, the digital processor reading the set of instructions stored in the memory for implementing an encoding method as claimed in claim 8.