Method, device, equipment and medium for processing video data

Abstract

The present disclosure generally relates to video coding and decoding, and more particularly to intra-block copy coding and decoding modes. For example, a method for processing video data is disclosed, the method comprising: receiving a video bitstream, the video bitstream comprising at least one block of a video frame, the at least one block comprising a current block; determining a first search area in the video frame; determining a second search area, wherein the second search area is a second candidate area for locating an IntraBC prediction block; identifying the IntraBC prediction block referenced by a block vector; determining a prediction based on a spatial relationship between the IntraBC prediction block, the first search area, and the second search area; and decoding at least a portion of the current block based on the determined prediction.

Description

[0001] Cross-references

[0002] This application is based on and claims the benefit of priority of U.S. non-provisional application No. 17 / 939,239, filed on September 7, 2022, entitled “Method and Apparatus for Intra Block Copy (IntraBC) Mode Coding with Search Range Restrictions”, which is based on and claims the benefit of priority of U.S. Provisional Application No. 63 / 245,678, filed on September 17, 2021, entitled “Method and Apparatus for Intra Block Copy (IntraBC) Mode Coding with Search Range Restrictions”, each of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure describes a set of advanced video coding techniques. More specifically, the disclosed techniques relate to the implementation and enhancement of intra-block copy (IntraBC, or IBC) in video encoding and decoding. Background Art

[0004] The background description provided herein is for the purpose of presenting the content of the present disclosure in general. To the extent described in this background section, the works of the presently named inventors and aspects of this description that may not otherwise qualify as prior art at the time of filing this application are neither explicitly nor implicitly admitted as prior art to the present disclosure.

[0005] Video encoding and decoding can be performed using inter-frame picture prediction with motion compensation. Uncompressed digital video can include a series of pictures, each picture having a spatial dimension of, for example, 1920x1080 luminance samples and associated fully sampled or subsampled chrominance samples. The series of pictures can have a fixed or variable picture rate (or frame rate) of, for example, 60 pictures per second or 60 frames per second. Uncompressed video has very high bit rate requirements for streaming or data processing. For example, at 8 bits per pixel per color channel, a video with a pixel resolution of 1920x1080, a frame rate of 60 frames per second, and a chrominance subsampling of 4:2:0 requires a bandwidth of nearly 1.5Gbit / s. One hour of such video requires more than 600GB of storage space.

[0006] One purpose of video encoding and decoding can be to reduce redundancy in an uncompressed input video signal by compression. Compression can help reduce the bandwidth and / or storage space requirements mentioned above, in some cases by two orders of magnitude or more. Lossless compression and lossy compression, as well as combinations thereof, can be employed. Lossless compression refers to a technique in which an exact copy of the original signal can be reconstructed from the compressed original signal through a decoding process. Lossy compression refers to an encoding / decoding process in which the original video information is not completely preserved during the encoding process and cannot be completely restored during the decoding process. When lossy compression is used, the reconstructed signal may not be identical to the original signal, although there is some information loss, but the distortion between the original signal and the reconstructed signal is small enough to make the reconstructed signal usable for the intended application. In the case of video, lossy compression is widely used in many applications. The amount of tolerable distortion depends on the application. For example, users of certain consumer video streaming applications can tolerate higher distortion than users of movie or television broadcast applications. The compression ratio achievable by a particular encoding algorithm can be selected or adjusted to reflect various distortion tolerances: higher tolerable distortion will generally allow encoding algorithms that produce higher losses and higher compression ratios.

[0007] Video encoders and decoders may utilize techniques from several broad categories and steps, including, for example, motion compensation, Fourier transforms, quantization, and entropy coding.

[0008] Video codec techniques may include a technique known as intra-coding. In intra-coding, sample values ​​are represented without reference to samples or other data from previously reconstructed reference pictures. In some video codecs, pictures are spatially subdivided into blocks of samples. When all blocks of samples are encoded in intra-mode, the picture may be an intra-picture. Intra-pictures and their derivatives (such as independent decoder refresh pictures) can be used to reset the decoder state and can therefore be used as the first picture in an encoded video bitstream and video session, or as a still image. The samples of the block after intra-prediction can then be transformed to the frequency domain, and the transform coefficients so generated can be quantized before entropy coding. Intra-prediction represents a technique for minimizing sample values ​​in the pre-transform domain. In some cases, the smaller the DC value after transformation and the smaller the AC coefficient, the fewer bits are needed to represent the entropy-coded block at a given quantization step size.

[0009] Conventional intra-frame coding, such as known from, for example, MPEG-2 generation coding techniques, does not use intra-frame prediction. However, some newer video compression techniques include techniques for attempting to encode / decode blocks based on, for example, surrounding sample data and / or metadata obtained during encoding / decoding of spatially adjacent data blocks that precede the data block being encoded or decoded within the frame in decoding order. Such techniques are hereinafter referred to as "intra-frame prediction" techniques. Note that, at least in some cases, intra-frame prediction uses only reference data from the current picture being reconstructed, and does not use reference data from other reference pictures.

[0010] Intra-frame prediction can take many different forms. When more than one such technique is available in a given video coding technique, the technique used may be referred to as an intra-frame prediction mode. One or more intra-frame prediction modes may be provided in a particular codec. In some cases, a mode may have sub-modes and / or may be associated with various parameters, and the mode / sub-mode and intra-frame coding parameters for a video block may be encoded separately or contained together in a mode codeword. Which codeword is used for a given mode / sub-mode / parameter combination can have an impact on the coding efficiency gain through intra-frame prediction, and so does the entropy coding technique used to convert the codeword into a bitstream.

[0011] H.264 introduced a certain intra-frame prediction mode, which was improved in H.265 and further improved in new coding techniques such as the Joint Exploration Model (JEM), the next generation video coding (Versatile Video Coding, VVC), and the Benchmark Set (BMS). Typically, for intra-frame prediction, the values ​​of neighboring samples that have become available can be used to form a predictor block. For example, the available values ​​of a specific set of neighboring samples along a specific direction and / or line can be copied to the predictor block. The reference to the direction used can be encoded in the bitstream, or it can be predicted itself.

[0012] refer to Figure 1A, depicted at the bottom right is a subset of 9 predictor directions specified out of the 33 possible predictor directions of H.265 (corresponding to the 33 angular modes out of the 35 intra modes specified in H.265). The point (101) where the arrows converge represents the sample being predicted. The arrows represent the direction in which the sample at 101 is predicted using neighboring samples. For example, arrow (102) indicates that sample (101) is predicted based on one or more neighboring samples in the upper right direction at an angle of 45 degrees to the horizontal direction. Similarly, arrow (103) indicates that sample (101) is predicted based on one or more neighboring samples in the lower left direction of sample (101) at an angle of 22.5 degrees to the horizontal direction.

[0013] Still refer to Figure 1A , a square block (104) of 4x4 samples is depicted in the upper left corner (indicated by the bold dashed line). The square block (104) contains 16 samples, each of which is labeled with "S" and its position in the Y dimension (e.g., row index) and its position in the X dimension (e.g., column index). For example, sample S21 is the second sample in the Y dimension (starting from the top) and the first sample in the X dimension (starting from the left). Similarly, sample S44 is the fourth sample in the block (104) in both the Y dimension and the X dimension. Since the size of the block is 4x4 samples, S44 is in the lower right corner. Example reference samples following a similar numbering scheme are also shown. The reference samples are labeled with R and their Y position (e.g., row index) and X position (column index) relative to the block (104). In both H.264 and H.265, prediction samples that are adjacent to the block being reconstructed are used.

[0014] The intra picture prediction of block 104 may start by copying reference sample values ​​from neighboring samples according to a signaled prediction direction. For example, assume that the encoded video bitstream includes signaling indicating the prediction direction of arrow (102) for this block 104, that is, the sample is predicted based on one or more prediction samples in the upper right direction at an angle of 45 degrees to the horizontal direction. In this case, samples S41, S32, S23 and S14 are predicted based on the same reference sample R05. Then, sample S44 is predicted based on reference sample R08.

[0015] In some cases, the values ​​of multiple reference samples may be combined, for example by interpolation, in order to calculate the reference sample; this may be done in particular when the direction is not divisible by 45 degrees.

[0016] As video coding techniques have continued to develop, the number of possible directions has increased. For example, in H.264 (2003), nine different directions were available for intra-frame prediction. This number increased to 33 in H.265 (2013), and at the time of this disclosure, up to 65 directions are supported in JEM / VVC / BMS. Experimental studies have been conducted to help identify the most appropriate intra-frame prediction directions, and certain techniques in entropy coding can be used to encode those most appropriate directions with a small number of bits, accepting a certain cost for less likely directions. In addition, the direction itself can sometimes be predicted based on the neighboring directions used in the intra-frame prediction of the already decoded neighboring blocks.

[0017] Figure 1B is a diagram (180) depicting 65 intra prediction directions according to JEM to illustrate the increasing number of prediction directions in various encoding techniques as they evolve over time.

[0018] The manner in which the intra prediction direction bits representing the prediction direction are mapped in the coded video bitstream may vary from one video coding technique to another, and, for example, may range from a simple direct mapping of prediction directions to intra prediction modes to codewords to complex adaptive schemes involving most likely modes and similar techniques. However, in all cases, there may be some directions that are statistically less likely to occur in the video content than some other directions. Since the goal of video compression is to reduce redundancy, in a well-designed video coding technique, those less likely directions will be represented by a larger number of bits than the more likely directions.

[0019] Inter-picture prediction or inter-prediction may be based on motion compensation. In motion compensation, sample data from a previously reconstructed picture or portion thereof (reference picture) may be used to predict a newly reconstructed picture or picture portion (e.g., block) after being spatially shifted in a direction indicated by a motion vector (hereinafter MV). In some cases, the reference picture may be the same as the picture currently being reconstructed. The MV may have two dimensions, X and Y, or three dimensions, with the third dimension indicating the reference picture being used (similar to the time dimension).

[0020] In some video compression techniques, the current MV applicable to a region of sample data can be predicted based on other MVs (e.g., based on other MVs that are spatially related to another region of sample data that is adjacent to the region being reconstructed and that precede the current MV in decoding order). Doing so can significantly reduce the total amount of data required to encode the MV by relying on removing redundancy in the related MVs, thereby improving the compression rate. MV prediction can work effectively, for example, because when encoding an input video signal derived from a camera (called natural video), there is a statistical probability that a larger area than the area to which a single MV applies moves in a similar direction in the video sequence, so in some cases, similar motion vectors derived from MVs of adjacent areas can be used to predict the larger area. This makes the actual MV of a given area similar or identical to the MV predicted from the surrounding MVs. Furthermore, after entropy coding, such an MV can be represented with fewer bits than the number of bits used when the MV is directly encoded rather than predicted from adjacent MVs. In some cases, MV prediction can be an example of lossless compression of a signal (i.e., MV) derived from the original signal (i.e., sample stream). In other cases, the MV prediction itself may be lossy, for example due to round-off errors when computing the prediction value from multiple surrounding MVs.

[0021] Various MV prediction mechanisms are described in H.265 / HEVC (ITU-T Recommendation H.265, "High Efficiency Video Coding", December 2016). Among the multiple MV prediction mechanisms specified by H.265, described below is a technique hereinafter referred to as "spatial merging".

[0022] Specifically, refer to Figure 2 , the current block (201) includes samples that have been discovered by the encoder during the motion search process, which can be predicted from a previous block of the same size that has been spatially offset. Instead of encoding the MV directly, the MV can be derived from metadata associated with one or more reference pictures (e.g., from the nearest reference picture (in decoding order)) using MVs associated with any of the five surrounding samples labeled A0, A1 and B0, B1, B2 (corresponding to 202 to 206, respectively). In H.265, MV prediction can use prediction values ​​from the same reference picture used by neighboring blocks. Summary of the invention

[0023] Aspects of the present disclosure relate generally to video encoding and decoding, and in particular, to video encoding and decoding in intra block copy mode.

[0024] Aspects of the present disclosure provide a method for processing video data. The method includes receiving a video bitstream, the video bitstream including at least one block of a video frame, the at least one block including a current block; determining a first search area in the video frame, wherein the first search area is a first candidate area for locating an intra-block copy (IntraBC) prediction block, wherein the first search area does not overlap with the current block and includes a block list, the IntraBC prediction block is a candidate block for IntraBC prediction of at least a portion of the current block; determining a second search area, wherein the second search area is a second candidate area for locating the IntraBC prediction block, the second search area including at least one of: (i) a subblock of the current block, and (ii) a neighboring block of the current block; identifying the IntraBC prediction block referenced by a block vector; determining a prediction based on a spatial relationship between the IntraBC prediction block, the first search area, and the second search area; and decoding at least a portion of the current block based on the determined prediction.

[0025] Aspects of the present disclosure also provide a video encoding or decoding device or apparatus, comprising a circuit configured to perform any one of the above method implementations.

[0026] Aspects of the present disclosure also provide a non-transitory computer-readable medium storing instructions, which, when executed by a computer for video decoding and / or encoding, cause the computer to perform a method for video decoding and / or encoding. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Other features, properties and various advantages of the disclosed subject matter will become more apparent from the following detailed description and the accompanying drawings, in which:

[0028] Figure 1A is a schematic diagram of an exemplary subset of intra prediction direction modes;

[0029] Figure 1B is a diagram of exemplary intra prediction directions;

[0030] Figure 2 A schematic diagram showing a current block and its surrounding spatial merging candidates for motion vector prediction in one example is shown;

[0031] Figure 3 A schematic diagram showing a simplified block diagram of a communication system according to an example embodiment;

[0032] Figure 4 A schematic diagram showing a simplified block diagram of a communication system according to an example embodiment;

[0033] Figure 5A schematic diagram showing a simplified block diagram of a video decoder according to an example embodiment;

[0034] Figure 6 A schematic diagram showing a simplified block diagram of a video encoder according to an example embodiment;

[0035] Figure 7 shows a block diagram of a video encoder according to another example embodiment;

[0036] Figure 8 shows a block diagram of a video decoder according to another example embodiment;

[0037] Fig. 9 A scheme for encoding block partitioning according to an exemplary embodiment of the present disclosure is shown;

[0038] Fig.10 Another scheme of coding block partitioning according to an exemplary embodiment of the present disclosure is shown;

[0039] Fig.11 Another scheme of coding block partitioning according to an exemplary embodiment of the present disclosure is shown;

[0040] Fig.12 An example of partitioning a basic block into coding blocks according to an example partitioning scheme is shown;

[0041] Fig.13 An exemplary ternary partitioning scheme is shown;

[0042] Fig.14 An exemplary quadtree binary tree coding block partitioning scheme is shown;

[0043] Fig.15 A scheme for partitioning a coding block into a plurality of transform blocks and a coding order of the transform blocks according to an exemplary embodiment of the present disclosure is shown;

[0044] Fig.16 Another scheme for partitioning a coding block into a plurality of transform blocks and a coding order of the transform blocks according to an example embodiment of the present disclosure is shown;

[0045] Fig.17 Another scheme for partitioning a coding block into multiple transform blocks according to an example embodiment of the present disclosure is shown;

[0046] Fig.18 The concept of intra-block copying (IBC) using a reconstructed coded block in the same frame to predict the current coded block is shown;

[0047] Fig.19 An exemplary reconstructed sample that can serve as a reference sample for an IBC is shown;

[0048] Fig. 20An exemplary reconstructed sample that may be used as a reference sample for an IBC is shown with some example limitations;

[0049] Fig.21 An exemplary on-chip reference sample memory (RSM) update mechanism for IBC is shown;

[0050] Fig. 22 Shows Fig.21 A spatial view of an exemplary on-chip RSM update mechanism;

[0051] Fig.23 Another exemplary on-chip reference sample memory (RSM) update mechanism for IBC is shown;

[0052] Fig.24 A comparison of spatial views of exemplary RSM update mechanisms for IBCs that split superblocks horizontally and vertically is shown;

[0053] Fig.25 shows exemplary non-local and local search areas for an IBC reference block;

[0054] Fig.26 shows exemplary prediction blocks for IBC employing local and non-local reference block search areas and proposed restrictions on prediction block selection;

[0055] Fig. 27 A flowchart showing a method according to an example embodiment of the present disclosure; and

[0056] Fig.28 A schematic diagram of a computer system according to an example embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0057] The present invention will be described in detail below with reference to the accompanying drawings, which are a part of the present invention and show specific examples of embodiments by way of illustration. However, please note that the present invention may be implemented in a variety of different forms, and therefore, the subject matter covered or claimed is intended to be construed as not limited to any embodiment set forth below. Please also note that the present invention may be embodied as a method, device, component, or system. Therefore, embodiments of the present invention may take the form of, for example, hardware, software, firmware, or any combination thereof.

[0058] Throughout the specification and claims, terms may have nuanced meanings that are suggested or implied by the context beyond their explicitly stated meanings. The phrases "in one embodiment" or "in some embodiments" as used herein do not necessarily refer to the same embodiment, and the phrases "in another embodiment" or "in other embodiments" as used herein do not necessarily refer to different embodiments. Similarly, the phrases "in one implementation" or "in some implementations" as used herein do not necessarily refer to the same implementation, and the phrases "in another implementation" or "in other implementations" as used herein do not necessarily refer to different implementations. For example, the claimed subject matter includes a combination of all or part of the exemplary embodiments / implementations.

[0059] In general, terms can be understood at least in part from the usage in the context. For example, terms such as "and", "or" or "and / or" used here can include various meanings, which can depend at least in part on the context in which these terms are used. Generally, if "or" is used to associate a list such as A, B or C, it is intended to represent A, B and C (here for inclusion) and A, B or C (here for exclusion). In addition, the terms "one or more" or "at least one" used here, at least in part depending on the context, can be used to describe any feature, structure or feature in a singular sense, or can be used to describe a combination of features, structures or features in a plural sense. Similarly, terms such as "one", "an" or "the / said" can also be understood to convey singular usage or convey plural usage, which depends at least in part on the context. In addition, the term "based on" or "determined by..." can be understood to not necessarily be intended to convey a set of exclusive factors, but may allow the presence of other factors that are not necessarily explicitly described, which also depends at least in part on the context.

[0060] Figure 3 A simplified block diagram of a communication system (300) according to an embodiment of the present disclosure is shown. The communication system (300) includes a plurality of terminal devices that can communicate with each other via, for example, a network (350). For example, the communication system (300) includes a first pair of terminal devices (310) and (320) interconnected via the network (350). Figure 3 In the example of , the first terminal device pair (310) and (320) can perform unidirectional data transmission. For example, the terminal device (310) can encode video data (such as a video picture stream collected by the terminal device (310)) for transmission to another terminal device (320) through the network (350). The encoded video data is transmitted in the form of one or more encoded video bitstreams. The terminal device (320) can receive the encoded video data from the network (350), decode the encoded video data to restore the video picture, and display the video picture based on the restored video data. The unidirectional data transmission can be implemented in applications such as media services.

[0061] In another example, the communication system (300) includes a second pair of terminal devices (330) and (340) that perform bidirectional transmission of encoded video data, which can be implemented, for example, during a video conferencing application. For bidirectional data transmission, in one example, each of the terminal devices (330) and (340) can encode video data (e.g., a video picture stream collected by the terminal device) to transmit to the other terminal device (330) and (340) through a network (350). Each of the terminal devices (330) and (340) can also receive the encoded video data transmitted by the other terminal device (330) and (340), and can decode the encoded video data to restore the video picture, and can display the video picture on an accessible display device based on the restored video data.

[0062] exist Figure 3 In the example of, terminal device (310), terminal device (320), terminal device (330) and terminal device (340) can be implemented as a server, a personal computer and a smart phone, but the applicability of the basic principles of the present disclosure may not be limited to this. Embodiments of the present disclosure can be implemented in a desktop computer, a laptop computer, a tablet computer, a media player, a wearable computer and / or a dedicated video conferencing device, etc. Network (350) represents any number or type of network that transmits encoded video data between terminal devices (310), terminal devices (320), terminal devices (330) and terminal devices (340), including, for example, wired (wired) and / or wireless communication networks. The communication network (350) can exchange data in circuit switching, packet switching and / or other types of channels. Representative networks may include telecommunication networks, local area networks, wide area networks and / or the Internet. For the purpose of this discussion, unless explicitly explained herein, the architecture and topology of the network (350) may be irrelevant to the operation of the present disclosure.

[0063] As examples of applications of the disclosed subject matter, Figure 4 is an exemplary block diagram of a communication system (400). Specifically, Figure 4 The placement of the video encoder and video decoder in a video streaming environment is shown. The disclosed subject matter is equally applicable to other video applications, including, for example, video conferencing, digital television broadcasting, gaming, virtual reality, storing compressed video on digital media including CDs, DVDs, memory sticks, etc., and the like.

[0064] The video streaming system may include a video acquisition subsystem (413), which may include a video source (401), such as a digital camera, for creating an uncompressed video picture or image stream (402). In an example, the video picture stream (402) includes samples recorded by the digital camera of the video source 401. The video picture stream (402), which is depicted as a thick line to emphasize the high amount of data compared to the encoded video data (404) (or encoded video bitstream), may be processed by an electronic device (420) that includes a video encoder (403) coupled to the video source (401). The video encoder (403) may include hardware, software, or a combination of hardware and software to implement or implement various aspects of the disclosed subject matter as described in more detail below. The encoded video data (404) (or encoded video bitstream (404)), depicted as thin lines to emphasize the lower amount of data compared to the uncompressed video picture stream (402), can be stored on the streaming server (405) for future use or directly stored in a downstream video device (not shown). One or more streaming client subsystems, such as Figure 4 The client subsystem (406) and the client subsystem (408) in the video transmission system can access the streaming server (405) to retrieve the copy (407) and the copy (409) of the encoded video data (404). The client subsystem (406) may include, for example, a video decoder (410) in the electronic device (430). The video decoder (410) decodes the incoming copy (407) of the encoded video data and produces an output video picture stream (411) that is uncompressed and can be presented on a display (412) (e.g., a display screen) or another presentation device (not depicted). The video decoder 410 can be configured to perform some or all of the various functions described in the present disclosure. In some streaming transmission systems, the encoded video data (404), (407) and (409) (e.g., video bitstreams) can be encoded according to certain video encoding / compression standards. Examples of these standards include ITU-T H.265 Recommendation. In an example, the video coding standard under development is informally referred to as Versatile Video Coding (VVC), and the disclosed subject matter can be used in the context of VVC and other video coding standards.

[0065] It should be noted that the electronic device (420) and the electronic device (430) may include other components (not shown). For example, the electronic device (420) may include a video decoder (not shown), and the electronic device (430) may also include a video encoder (not shown).

[0066] Figure 5is a block diagram of a video decoder (510) according to any of the following embodiments of the present disclosure. The video decoder (510) may be included in an electronic device (530). The electronic device (530) may include a receiver (531) (e.g., a receiving circuit). The video decoder (510) may be used to replace Figure 4 A video decoder (510) in an example of FIG.

[0067] The receiver (531) may receive one or more encoded video sequences to be decoded by the video decoder (510). In the same or another embodiment, one encoded video sequence is decoded at a time, wherein the decoding of each encoded video sequence is independent of the other encoded video sequences. Each video sequence may be associated with multiple video frames or images. The encoded video sequence may be received from a channel (501), which may be a hardware / software link to a storage device storing the encoded video data or a streaming source that transmits the encoded video data. The receiver (531) may receive the encoded video data and other data, such as encoded audio data and / or auxiliary data streams, which may be forwarded to their respective processing circuits (not depicted). The receiver (531) may separate the encoded video sequence from the other data. To prevent network jitter, a buffer memory (515) may be provided between the receiver (531) and the entropy decoder / parser (520) (hereinafter referred to as "parser (520)"). In some applications, the buffer memory (515) may be implemented as part of the video decoder (510). In other applications, the buffer memory (515) may be provided outside the video decoder (510) and separate therefrom (not shown). In other applications, a buffer memory (not depicted) may be provided outside the video decoder (510) to, for example, prevent network jitter, and another additional buffer memory (515) may be configured inside the video decoder (510) to, for example, handle playback timing. When the receiver (531) receives data from a storage / forward device with sufficient bandwidth and controllability or from an isochronous network, it may not be necessary to configure the buffer memory (515), or the buffer memory may be made smaller. For use on a best-effort packet network such as the Internet, a buffer memory (515) of sufficient size may also be required, and the size of the buffer memory may be relatively large. Such a buffer memory may be implemented with an adaptive size and may be implemented at least in part in an operating system or similar element (not depicted) external to the video decoder (510).

[0068] The video decoder (510) may include a parser (520) to reconstruct symbols (521) from the encoded video sequence. The categories of these symbols include information for managing the operation of the video decoder (510) and potential information for controlling a display device such as a display (512) (e.g., a display screen), which may or may not be an integral part of the electronic device (530) but may be coupled to the electronic device (530), such as Figure 5 As shown in . The control information for the display device may be a parameter set fragment (not shown) of Supplemental Enhancement Information (SEI message) or Video Usability Information (VUI). The parser (520) may parse / entropy decode the encoded video sequence received by the parser (520). The entropy encoding of the encoded video sequence may be performed according to a video coding technique or standard, and may follow various principles, including variable length coding, Huffman coding, arithmetic coding with or without context sensitivity, and the like. The parser (520) may extract a subgroup parameter set of at least one subgroup of the subgroups of pixels in the video decoder from the encoded video sequence based on at least one parameter corresponding to the subgroup. The subgroup may include a Group of Pictures (GOP), a picture, a tile, a slice, a macroblock, a Coding Unit (CU), a block, a Transform Unit (TU), a Prediction Unit (PU), and the like. The parser (520) may also extract information from the encoded video sequence, such as transform coefficients (eg, Fourier transform coefficients), quantizer parameter values, motion vectors, and so on.

[0069] The parser (520) may perform entropy decoding / parsing operations on the video sequence received from the buffer memory (515), thereby creating symbols (521).

[0070] Depending on the type of coded video picture or part of coded video picture (e.g., inter-picture and intra-picture, inter-block and intra-block) and other factors, the reconstruction of symbol (521) may involve multiple different processing or functional units. The units involved and the manner of involvement may be controlled by subgroup control information parsed by parser (520) from the coded video sequence. For the sake of brevity, such subgroup control information flow between parser (520) and the multiple processing or functional units described below is not described.

[0071] In addition to the functional blocks already mentioned, the video decoder (510) can be conceptually subdivided into several functional units as described below. In a practical embodiment operating under commercial constraints, many of these functional units interact closely with each other and can be at least partially integrated with each other. However, for the purpose of clearly describing the various functions of the disclosed subject matter, the present disclosure adopts the conceptual subdivision into functional units hereinafter.

[0072] The first unit may include a sealer / inverse transform unit (551). The sealer / inverse transform unit (551) may receive quantized transform coefficients as symbols (521) and control information from the parser (520), including information indicating which type of inverse transform to use, block size, quantization factors / parameters, quantization scaling matrix, etc. The sealer / inverse transform unit (551) may output a block including sample values, which may be input into the aggregator (555).

[0073] In some cases, the output samples of the scaler / inverse transform unit (551) may belong to intra-coded blocks, i.e., blocks that do not use predictive information from previously reconstructed pictures, but may use predictive information from previously reconstructed portions of the current picture. Such predictive information may be provided by an intra-picture prediction unit (552). In some cases, the intra-picture prediction unit (552) may generate a block of the same size and shape as the block being reconstructed using surrounding block information that has already been reconstructed and stored in a current picture buffer (558). For example, the current picture buffer (558) buffers a partially reconstructed current picture and / or a fully reconstructed current picture. In some implementations, the aggregator (555) may add the prediction information generated by the intra-prediction unit (552) to the output sample information provided by the scaler / inverse transform unit (551) on a per-sample basis.

[0074] In other cases, the output samples of the scaler / inverse transform unit (551) may belong to an inter-coded and potentially motion compensated block. In this case, the motion compensated prediction unit (553) may access the reference picture memory (557) to extract samples for intra picture prediction. After the extracted samples are motion compensated according to the symbols (521) belonging to the block, these samples may be added to the output of the scaler / inverse transform unit (551) (the illustration of unit 551 is called residual samples or residual signal) by the aggregator (555) to generate output sample information. The address in the reference picture memory (557) from which the motion compensated prediction unit (553) extracts the predicted samples is controlled by a motion vector, and the motion vector is used by the motion compensated prediction unit (553) in the form of a symbol (521), which may have, for example, an X, Y component (offset) and a reference picture component (time). Motion compensation may also include interpolation of sample values ​​extracted from the reference picture memory (557) when using sub-sample accurate motion vectors, and may also be associated with motion vector prediction mechanisms, etc.

[0075] The output samples of the aggregator (555) may be subjected to various loop filtering techniques in a loop filter unit (556). The video compression techniques may include in-loop filter techniques controlled by parameters included in the coded video sequence (also referred to as the coded video bitstream) and available to the loop filter unit (556) as symbols (521) from the parser (520), however, the video compression techniques may also be responsive to meta-information obtained during decoding of a coded picture or a previous (in decoding order) portion of the coded video sequence, as well as to sample values ​​that have been previously reconstructed and loop filtered. Several types of loop filters may be included as part of the loop filter unit 556 in various orders, as will be described in further detail below.

[0076] The output of the loop filter unit (556) may be a sample stream that may be output to a display device (512) and stored in a reference picture memory (557) for subsequent inter-picture prediction.

[0077] Once fully reconstructed, certain coded pictures may be used as reference pictures for future inter-picture prediction. For example, once the coded picture corresponding to the current picture is fully reconstructed, and the coded picture is identified as a reference picture (e.g., by the parser (520)), the current picture buffer (558) may become part of the reference picture memory (557), and a new current picture buffer may be reallocated before starting reconstruction of a subsequent coded picture.

[0078] The video decoder (510) may perform decoding operations according to a predetermined video compression technique adopted in, for example, the ITU-T H.265 Recommendation standard. The coded video sequence may conform to the syntax specified by the video compression technique or standard used in the sense that the coded video sequence follows the syntax of the video compression technique or standard and the profile recorded in the video compression technique or standard. Specifically, the profile may select certain tools from all the tools available in the video compression technique or standard as the only tools available for use under the profile. For compliance, it is also required that the complexity of the coded video sequence is within the range defined by the hierarchy of the video compression technique or standard. In some cases, the hierarchy limits the maximum picture size, the maximum frame rate, the maximum reconstruction sampling rate (measured in, for example, mega samples per second), the maximum reference picture size, etc. In some cases, the limits set by the hierarchy may be further limited by the Hypothetical Reference Decoder (HRD) specification and the metadata of the HRD buffer management signaled in the coded video sequence.

[0079] In some example embodiments, the receiver (531) may receive additional (redundant) data along with the encoded video. The additional data may be included as part of the encoded video sequence. The additional data may be used by the video decoder (510) to properly decode the data and / or more accurately reconstruct the original video data. The additional data may be in the form of, for example, temporal, spatial or signal-to-noise ratio (SNR) enhancement layers, redundant slices, redundant pictures, forward error correction codes, etc.

[0080] Figure 6 A block diagram of a video encoder (603) according to an example embodiment of the present disclosure is shown. The video encoder (603) may be included in an electronic device (620). The electronic device (620) may also include a transmitter (640) (e.g., a transmission circuit). The video encoder (603) may be used to replace Figure 4 A video encoder (603) in the example of FIG.

[0081] The video encoder (603) can be used to obtain the video source (601) (not Figure 6 In another example, the video source (601) may be implemented as a part of the electronic device (620) to receive video samples, and the video source may capture video images to be encoded by the video encoder (603). In another example, the video source (601) may be implemented as a part of the electronic device (620).

[0082] The video source (601) may provide a source video sequence in the form of a digital video sample stream to be encoded by the video encoder (603), the digital video sample stream may have any suitable bit depth (e.g., 8-bit, 10-bit, 12-bit, ...), any color space (e.g., BT.601 YCrCB, RGB, XYZ, ...), and any suitable sampling structure (e.g., YCrCb 4:2:0, YCrCb 4:4:4). In a media service system, the video source (601) may be a storage device capable of storing previously prepared videos. In a video conferencing system, the video source (601) may be a camera that captures local image information as a video sequence. The video data may be provided as a plurality of separate pictures or images that are given motion when viewed sequentially. The picture itself may be constructed as a spatial pixel array, wherein each pixel may include one or more samples depending on the sampling structure, color space, etc. used. The relationship between pixels and samples may be easily understood by those skilled in the art. The following description focuses on the samples.

[0083] According to some example embodiments, the video encoder (603) may encode and compress pictures of a source video sequence into an encoded video sequence (643) in real time or under any other time constraints required by the application. Implementing an appropriate encoding speed constitutes a function of the controller (650). In some embodiments, the controller (650) may be functionally coupled to and control other functional units as described below. For the sake of brevity, the coupling is not indicated in the figure. The parameters set by the controller (650) may include rate control related parameters (picture skipping, quantizer, lambda value of rate-distortion optimization technology...), picture size, picture group (GOP) layout, maximum motion vector search range, etc. The controller (650) may be configured to have other suitable functions that are related to the video encoder (603) optimized for a certain system design.

[0084] In some example embodiments, the video encoder (603) may be configured to operate in an encoding loop. As a simple description, in an example, the encoding loop may include a source encoder (630) (e.g., responsible for creating symbols, such as a symbol stream, based on an input picture to be encoded and a reference picture) and a (local) decoder (633) embedded in the video encoder (603). The decoder (633) reconstructs the symbols to create sample data in a manner similar to the way the (remote) decoder creates sample data, even if the embedded decoder 633 processes the encoded video stream by the source encoder 630 without entropy coding (because in the video compression technology considered by the disclosed subject matter, any compression between the symbols in the entropy coding and the encoded video bit stream can be lossless). The reconstructed sample stream (sample data) is input to a reference picture memory (634). Since the decoding of the symbol stream produces a bit-accurate result that is independent of the decoder location (local or remote), the contents in the reference picture memory (634) are also bit-accurately corresponding between the local encoder and the remote encoder. In other words, the reference picture samples "seen" by the prediction part of the encoder are exactly the same sample values ​​that the decoder will "see" when using the prediction during decoding. This basic principle of reference picture synchronization (and the drift that occurs when synchronization cannot be maintained, e.g. due to channel errors) is used to improve encoding quality.

[0085] The operation of the "local" decoder (633) can be combined with the above Figure 5 The "remote" decoder of the video decoder (510) described in detail is identical. However, additional brief reference is made to Figure 5 , when symbols are available and the entropy encoder (645) and parser (520) are capable of losslessly encoding / decoding the symbols into an encoded video sequence, the entropy decoding portion of the video decoder (510), including the buffer memory (515) and the parser (520), may not be fully implemented in the local decoder (633) in the encoder.

[0086] At this point, it can be observed that any decoder technology other than parsing / entropy decoding that may only exist in the decoder may also necessarily need to exist in the corresponding encoder in substantially the same functional form. For this reason, the disclosed subject matter may sometimes focus on decoder operations, which are partially related to the decoding of the encoding side. Thereby, the description of encoder technology can be simplified because encoder technology is mutually inverse to the decoder technology described comprehensively. A more detailed description of the encoder is provided below only in certain areas or aspects.

[0087] During operation, in some example implementations, the source encoder (630) may perform motion compensated predictive coding. The motion compensated predictive coding predictively encodes an input picture with reference to one or more previously encoded pictures from a video sequence designated as "reference pictures". In this manner, the encoding engine (632) encodes the color channel differences (or residuals) between pixel blocks of the input picture and pixel blocks of a reference picture that may be selected as a prediction reference for the input picture. The term "residual" and its adjective form "residual" may be used interchangeably.

[0088] The local video decoder (633) may decode the encoded video data of the picture that may be designated as the reference picture based on the symbol created by the source encoder (630). The operation of the encoding engine (632) may advantageously be a lossy process. When the encoded video data is available at the video decoder ( Figure 6 When the video sequence is decoded at a remote location (not shown), the reconstructed video sequence may typically be a copy of the source video sequence with some errors. The local video decoder (633) replicates the decoding process that may be performed by the video decoder on the reference picture and may cause the reconstructed reference picture to be stored in the reference picture memory (634). In this way, the video encoder (603) may locally store a copy of the reconstructed reference picture that has common content (absent transmission errors) with the reconstructed reference picture to be obtained by the remote video decoder.

[0089] The predictor (635) may perform a prediction search for the encoding engine (632). That is, for a new picture to be encoded, the predictor (635) may search the reference picture memory (634) for sample data (as candidate reference pixel blocks) or certain metadata, such as reference picture motion vectors, block shapes, etc., that may serve as appropriate prediction references for the new picture. The predictor (635) may operate on a pixel block by pixel block basis to find a suitable prediction reference. In some cases, as determined by the search results obtained by the predictor (635), the input picture may have prediction references taken from multiple reference pictures stored in the reference picture memory (634).

[0090] The controller (650) may manage encoding operations of the source encoder (630), including, for example, setting parameters and subgroup parameters for encoding video data.

[0091] The outputs of all the above functional units may be entropy encoded in an entropy encoder (645). The entropy encoder (645) performs lossless compression on the symbols generated by the various functional units according to techniques such as Huffman coding, variable length coding, arithmetic coding, etc., thereby transforming the symbols into a coded video sequence.

[0092] The transmitter (640) may buffer the encoded video sequence created by the entropy encoder (645) in preparation for transmission over a communication channel (660), which may be a hardware / software link to a storage device where the encoded video data will be stored. The transmitter (640) may combine the encoded video data from the video encoder (603) with other data to be transmitted, such as encoded audio data and / or ancillary data streams (source not shown).

[0093] The controller (650) may manage the operation of the video encoder (603). During encoding, the controller (650) may assign a certain coded picture type to each coded picture, but this may affect the coding techniques that can be applied to the corresponding picture. For example, a picture may generally be assigned to any of the following picture types:

[0094] An intra picture (I picture) may be a picture that can be encoded and decoded without using any other picture in the sequence as a prediction source. Some video codecs allow different types of intra pictures, including, for example, Independent Decoder Refresh ("IDR") pictures. Those of ordinary skill in the art are aware of the variations of I pictures and their corresponding applications and features.

[0095] A predictive picture (P picture) may be a picture that can be encoded and decoded using intra prediction or inter prediction, which uses at most one motion vector and a reference index to predict sample values ​​for each block.

[0096] Bidirectional predictive pictures (B pictures), which can be pictures that can be encoded and decoded using intra prediction or inter prediction, which uses up to two motion vectors and reference indices to predict the sample values ​​of each block. Similarly, multiple predictive pictures can use more than two reference pictures and associated metadata for reconstructing a single block.

[0097] The source picture may typically be spatially subdivided into a plurality of coding blocks of samples (e.g., blocks of 4×4, 8×8, 4×8, or 16×16 samples), and encoded block by block. These blocks may be predictively coded with reference to other (already coded) blocks, which are determined by the coding allocation applied to the corresponding picture of the block. For example, a block of an I picture may be non-predictively coded, or the block may be predictively coded (spatial prediction or intra-frame prediction) with reference to already coded blocks of the same picture. A pixel block of a P picture may be predictively coded by spatial prediction with reference to a previously coded reference picture or by temporal prediction. A block of a B picture may be predictively coded by spatial prediction with reference to one or two previously coded reference pictures or by temporal prediction. For other purposes, the source picture or the intermediate processed picture may be subdivided into other types of blocks. The division of coding blocks and other types of blocks may or may not follow the same approach, as described in further detail below.

[0098] The video encoder (603) may perform encoding operations according to a predetermined video encoding technique or standard, such as ITU-T H.265 Recommendation. In operation, the video encoder (603) may perform various compression operations, including predictive encoding operations that exploit temporal and spatial redundancy in an input video sequence. Thus, the encoded video data may conform to the syntax specified by the video encoding technique or standard used.

[0099] In some exemplary embodiments, the transmitter (640) may transmit additional data when transmitting the encoded video. The source encoder (630) may include such data as part of the encoded video sequence. The additional data may include other forms of redundant data such as temporal / spatial / SNR enhancement layers, redundant pictures and slices, SEI messages, VUI parameter set fragments, etc.

[0100] The captured video may be taken as multiple source pictures (video pictures) in a temporal sequence. Intra-picture prediction (often shortened to intra-prediction) exploits spatial correlations in a given picture, while inter-picture prediction exploits temporal or other correlations between pictures. For example, a particular picture being encoded / decoded is divided into blocks, and the particular picture being encoded / decoded is referred to as the current picture. When a block in the current picture is similar to a reference block in a reference picture that was previously encoded in the video and is still buffered, the block in the current picture may be encoded by a vector called a motion vector. The motion vector points to a reference block in a reference picture, and in the case where multiple reference pictures are used, the motion vector may have a third dimension that identifies the reference picture.

[0101] In some example embodiments, bidirectional prediction techniques may be used in inter-picture prediction. According to the bidirectional prediction technique, two reference pictures are used, such as a first reference picture and a second reference picture that are both before the current picture in the video in decoding order (but may be in the past and future, respectively, in display order). A block in the current picture may be encoded by a first motion vector pointing to a first reference block in the first reference picture and a second motion vector pointing to a second reference block in the second reference picture. The block may be jointly predicted by a combination of the first reference block and the second reference block.

[0102] In addition, merge mode technology can be used in inter-picture prediction to improve coding efficiency.

[0103] According to some example embodiments of the present disclosure, predictions such as inter-picture prediction and intra-picture prediction are performed in units of blocks. For example, a picture in a video picture sequence is partitioned into coding tree units (CTUs) for compression, and the CTUs in the picture may have the same size, such as 128×128 pixels, 64×64 pixels, 32×32 pixels, or 16×16 pixels. Typically, a CTU may include three parallel coding tree blocks (CTBs): one luminance CTB and two chrominance CTBs. Each CTU may be recursively quadtree split into one or more coding units (CUs). For example, a 64×64 pixel CTU may be split into a 64×64 pixel CU, or four 32×32 pixel CUs. Each of one or more of the 32×32 blocks may be further split into four CUs of 16×16 pixels. In some exemplary embodiments, each CU may be analyzed during encoding to determine a prediction type for the CU among various prediction types (e.g., an inter-prediction type or an intra-prediction type). Depending on temporal and / or spatial predictability, a CU can be split into one or more prediction units (PUs). Typically, each PU includes a luminance prediction block (PB) and two chrominance PBs. In one embodiment, the prediction operation in the codec (encoding / decoding) is performed in units of prediction blocks. Splitting a CU into PUs (or PBs of different color channels) can be performed in various spatial modes. For example, a luminance or chrominance PB may include a matrix of sample values ​​(e.g., luminance values), such as 8×8 pixels, 16×16 pixels, 8×16 pixels, 16×8 pixels, etc.

[0104] Figure 7A diagram of a video encoder (703) according to another example embodiment of the present disclosure is shown. The video encoder (703) is configured to receive a processed block (e.g., a prediction block) of sample values ​​within a current video picture in a sequence of video pictures and encode the processed block into an encoded picture that is part of an encoded video sequence. The example video encoder (703) may be used instead of Figure 4 The video encoder (403) in the example.

[0105] For example, the video encoder (703) receives a matrix of sample values ​​for a processing block, which is, for example, a prediction block of 8×8 samples, etc. The video encoder (703) then uses, for example, rate-distortion optimization (RDO) to determine whether to use intra mode, inter mode, or bidirectional prediction mode to best encode the processing block. When it is determined that the processing block is encoded in intra mode, the video encoder (703) may use intra prediction techniques to encode the processing block into an encoded picture; and when it is determined that the processing block is encoded in inter mode or bidirectional prediction mode, the video encoder (703) may encode the processing block into an encoded picture using inter prediction or bidirectional prediction techniques, respectively. In some example embodiments, merge mode may be used as a sub-mode of inter-picture prediction, in which motion vectors are derived from one or more motion vector predictors without the aid of encoded motion vector components external to the predictor. In some other example embodiments, there may be motion vector components applicable to the subject block. Therefore, the video encoder (703) may include Figure 7 Components not explicitly shown, such as a mode decision module for determining a prediction mode for a processing block.

[0106] exist Figure 7 In the example of FIG. 7 , the video encoder ( 703 ) includes Figure 7 An inter-frame encoder (730), an intra-frame encoder (722), a residual calculator (723), a switch (726), a residual encoder (724), a common controller (721), and an entropy encoder (725) coupled together are shown in an exemplary arrangement.

[0107] The inter-frame encoder (730) is configured to receive samples of a current block (e.g., a processing block), compare the block with one or more reference blocks in a reference picture (e.g., blocks in a previous picture and a subsequent picture in display order), generate inter-frame prediction information (e.g., redundant information description according to an inter-frame coding technique, motion vectors, merge mode information), and calculate an inter-frame prediction result (e.g., a predicted block) based on the inter-frame prediction information using any suitable technique. In some examples, the reference picture is encoded using a decoded image embedded in a decoded image. Figure 6 The decoding unit 633 in the example encoder 620 (such as Figure 7The residual decoder 728 (as shown in further detail below) is a decoded reference picture decoded based on the encoded video information.

[0108] The intra encoder (722) is configured to receive samples of a current block (e.g., a processing block), compare the block with an encoded block in the same picture, generate quantization coefficients after transformation, and in some cases also generate intra prediction information (e.g., intra prediction direction information according to one or more intra coding techniques). The intra encoder (722) can calculate an intra prediction result (e.g., a predicted block) based on the intra prediction information and a reference block in the same picture.

[0109] The general controller (721) can be configured to determine general control data and control other components of the video encoder (703) based on the general control data. In an example, the general controller (721) determines a prediction mode for a block and provides a control signal to a switch (726) based on the prediction mode. For example, when the prediction mode is an intra-frame mode, the general controller (721) controls the switch (726) to select an intra-frame mode result for use by the residual calculator (723), and controls the entropy encoder (725) to select intra-frame prediction information and add the intra-frame prediction information to the bitstream; and when the prediction mode for the block is an inter-frame mode, the general controller (721) controls the switch (726) to select an inter-frame prediction result for use by the residual calculator (723), and controls the entropy encoder (725) to select inter-frame prediction information and add the inter-frame prediction information to the bitstream.

[0110] The residual calculator (723) may be configured to calculate the difference (residual data) between the received block and the prediction result of the block selected from the intra encoder (722) or the inter encoder (730). The residual encoder (724) may be configured to encode the residual data to generate a transform coefficient. For example, the residual encoder (724) may be configured to transform the residual data from the spatial domain to the frequency domain to generate a transform coefficient. The transform coefficient is then subjected to a quantization process to obtain a quantized transform coefficient. In various example embodiments, the video encoder (703) further includes a residual decoder (728). The residual decoder (728) is configured to perform an inverse transform and generate decoded residual data. The decoded residual data may be appropriately used by the intra encoder (722) and the inter encoder (730). For example, the inter encoder (730) may generate a decoded block based on the decoded residual data and the inter prediction information, and the intra encoder (722) may generate a decoded block based on the decoded residual data and the intra prediction information. The decoded blocks are appropriately processed to generate a decoded picture, and the decoded picture may be buffered in a memory circuit (not shown) and used as a reference picture.

[0111] The entropy encoder (725) may be configured to format the bitstream to include the encoded blocks and perform entropy encoding. The entropy encoder (725) may be configured to include various information in the bitstream. For example, the entropy encoder (725) may be configured to include general control data, selected prediction information (e.g., intra-frame prediction information or inter-frame prediction information), residual information, and other suitable information in the bitstream. When the block is encoded in the merge sub-mode of the inter-frame mode or the bidirectional prediction mode, there is no residual information.

[0112] Figure 8 A diagram of an example video decoder (810) according to another embodiment of the present disclosure is shown. The video decoder (810) is configured to receive an encoded picture as part of an encoded video sequence and decode the encoded picture to generate a reconstructed picture. In an example, the video decoder (810) may be used instead of Figure 4 A video decoder (410) in an example of FIG.

[0113] exist Figure 8 In the example of FIG. 8 , the video decoder ( 810 ) includes Figure 8 An entropy decoder (871), an inter-frame decoder (880), a residual decoder (873), a reconstruction module (874), and an intra-frame decoder (872) coupled together are shown in the example arrangement of.

[0114] The entropy decoder (871) may be configured to reconstruct certain symbols from the encoded picture, which represent syntax elements that constitute the encoded picture. Such symbols may include, for example, a mode for encoding the block (e.g., intra mode, inter mode, bidirectional prediction mode, merge submode, or other submode), prediction information (e.g., intra prediction information or inter prediction information) that may identify certain samples or metadata for prediction by the intra decoder (872) or the inter decoder (880), residual information in the form of, for example, quantized transform coefficients, and the like. In an example, when the prediction mode is inter or bidirectional prediction mode, the inter prediction information is provided to the inter decoder (880); and when the prediction type is an intra prediction type, the intra prediction information is provided to the intra decoder (872). The residual information may be subjected to inverse quantization and provided to the residual decoder (873).

[0115] The inter-frame decoder (880) may be configured to receive the inter-frame prediction information and generate an inter-frame prediction result based on the inter-frame prediction information.

[0116] The intra decoder (872) may be configured to receive intra prediction information and generate a prediction result based on the intra prediction information.

[0117] The residual decoder (873) may be configured to perform inverse quantization to extract dequantized transform coefficients, and process the dequantized transform coefficients to transform the residual from the frequency domain to the spatial domain. The residual decoder (873) may also utilize certain control information (to include a quantizer parameter QP), and this information may be provided by the entropy decoder (871) (the data path is not indicated because this is only low-data-volume control information).

[0118] The reconstruction module (874) can be configured to combine the residual output by the residual decoder (873) with the prediction result (which can be output by the inter-frame prediction module or the intra-frame prediction module, depending on the specific situation) in the spatial domain to form a reconstructed block, which forms part of the reconstructed picture, which in turn is part of the reconstructed video. It should be noted that other suitable operations such as deblocking operations can also be performed to improve visual quality.

[0119] It should be noted that the video encoders (403), (603) and (703) and the video decoders (410), (510) and (810) may be implemented using any suitable technology. In some example embodiments, the video encoders (403), (603) and (703) and the video decoders (410), (510) and (810) may be implemented using one or more integrated circuits. In another embodiment, the video encoders (403), (603) and (703) and the video decoders (410), (510) and (810) may be implemented using one or more processors that execute software instructions.

[0120] Turning to the block partitioning for encoding and decoding, the general partitioning can start from the basic block and can follow a predefined set of rules, a specific pattern, a partition tree or any partition structure or scheme. Partitioning can be hierarchical and recursive. After following any of the example partitioning processes described below or other processes or combinations thereof to divide or partition the basic block, a final set of partitions or coding blocks can be obtained. Each of these partitions can be in one of the various partition levels in the partition hierarchy and can have various shapes. Each partition can be referred to as a coding block (CB). For the various example partitioning implementations further described below, each result CB can be any allowed size and partition level. Such partitions are called coding blocks because they can form units to which some basic coding / decoding decisions can be made, and coding / decoding parameters can be optimized, determined and signaled in the encoded video bitstream. The highest or deepest level in the final partition represents the depth of the coding block partition structure of the tree. The coding block can be a luminance coding block or a chrominance coding block. The CB tree structure of each color can be referred to as a coding block tree (CBT).

[0121] The coding blocks of all color channels can be collectively referred to as coding units (CUs). The hierarchical structure of all color channels can be collectively referred to as coding tree units (CTUs). The partitioning modes or structures of various color channels in a CTU may be the same or different.

[0122] In some implementations, the partition tree schemes or structures for luma and chroma channels may not need to be the same. In other words, luma and chroma channels may have separate coding tree structures or modes. In addition, whether luma and chroma channels use the same or different coding partition tree structures and the coding partition tree structures actually used may depend on whether the slice being encoded is a P, B, or I slice. For example, for an I slice, the chroma channel and the luma channel may have separate coding partition tree structures or coding partition tree structure modes, while for a P or B slice, the luma and chroma channels may share the same coding partition tree scheme. When a separate coding partition tree structure or mode is applied, the luma channel may be partitioned into CBs by one coding partition tree structure, and the chroma channel may be partitioned into chroma CBs by another coding partition tree structure.

[0123] In some example implementations, a predetermined partitioning scheme may be applied to basic blocks. Fig. 9 As shown, the example 4-way partition tree can start from a first predefined level (e.g., 64x64 block level or other size, as a basic block size), and the basic blocks can be hierarchically partitioned down to a predefined lowest level (e.g., 4x4 level). For example, the basic blocks can be affected by four predefined partitioning options or modes indicated by 902, 904, 906 and 908, where the partition designated as R can be used for recursive partitioning because Fig. 9 The same partitioning options shown can be repeated at lower scales until the lowest level (e.g., 4x4 level). In some implementations, additional restrictions can be applied Fig. 9 The partition scheme of Fig. 9 In the implementation of , it can be rectangular partitions (for example, 1:2 / 2:1 rectangular partitions), but these rectangular partitions cannot be recursive, while square partitions can be recursive. If necessary, continue Fig. 9 The recursive partitioning of generates a final set of coding blocks. The coding tree depth can be further defined to indicate the split depth from the root node or root block. For example, the coding tree depth of the root node or root block (e.g., 64x64 block) can be set to 0, and the root block can be split according to Fig. 9 After being further split once, the coding tree depth increases by 1. For the above scheme, the maximum or deepest level of the minimum partition from 64x64 basic block to 4x4 will be 4 (starting from level 0). This partitioning scheme can be applied to one or more color channels. Each color channel can be divided into Fig. 9Alternatively, two or more color channels may share Fig. 9 The same hierarchical pattern tree (e.g., the same partitioning pattern or option in a predefined pattern can be selected for two or more color channels at each hierarchical level).

[0124] Fig.10 Another example predefined partitioning pattern that can be recursively partitioned to form a partition tree is shown. Fig.10 As shown, an example 10-way partition structure or pattern may be predefined. A root block may start from a predefined level (eg, from a basic block at a 128×128 level or a 64×64 level). Fig.10 Example partition structures include various 2:1 / 1:2 and 4:1 / 1:4 rectangular partitions. Fig.10 The partition type with three sub-partitions represented as 1002, 1004, 1006 and 1008 in the second row of the table may be referred to as a "T-type" partition. The "T-type" partitions 1002, 1004, 1006 and 1008 may be referred to as a left T-type, an upper T-type, a right T-type and a lower T-type. In some example implementations, further subdivision is not allowed. Fig.10 The coding tree depth may be further defined to indicate the split depth from the root node or root block. For example, the coding tree depth of the root node or root block (e.g., 128x128 block) may be set to 0, and the coding tree depth of the root block may be set to 0 according to Fig.10 After being further split once, the coding tree depth increases by 1. In some implementations, only full square partitions in 1010 can be divided according to Fig.10 In other words, for the square partitions within the T-patterns 1002, 1004, 1006, and 1008, recursive partitioning may not be allowed. Fig.10 The recursive partitioning process of generates a final set of coding blocks. This scheme can be applied to one or more color channels. In some implementations, the use of partitions below the 8×8 level can be made more flexible. For example, 2×2 chroma inter-frame prediction can be used in some cases.

[0125] In some other implementations for coding block partitioning, a quadtree structure can be used to split a basic block or an intermediate block into quadtree partitions. This quadtree splitting can be applied hierarchically and recursively to any square partition. Whether a basic block, intermediate block, or partition can be further quadtree split can be applicable to various local characteristics of the basic block, intermediate block, or partition. The quadtree partitions at the picture boundaries can be further adjusted. For example, an implicit quadtree splitting can be performed at the picture boundaries to keep the block quadtree split until the size fits the picture boundary.

[0126] In some other example implementations, hierarchical binary partitioning from basic blocks can be used. For such a scheme, a basic block or an intermediate block can be divided into two partitions. The binary partitioning can be horizontal or vertical. For example, a horizontal binary partitioning can split a basic block or an intermediate block into equal right and left partitions. Similarly, a vertical binary partitioning can split a basic block or an intermediate block into equal upper and lower partitions. This binary partitioning can be hierarchical and recursive. It can be decided at each of the basic blocks or intermediate blocks whether the binary partitioning scheme should be continued, and if it is determined to further implement the scheme, horizontal or vertical binary partitioning should be used. In some implementations, further partitioning can be stopped at a predefined minimum partition size (in one dimension or two dimensions). Alternatively, further partitioning can be stopped once a predefined partitioning level or depth from a basic block is reached. In some implementations, the aspect ratio of the partition can be limited. For example, the aspect ratio of the partition can be not less than 1:4 (or greater than 4:1). Therefore, a vertical stripe partition with a vertical to horizontal aspect ratio of 4:1 can only be further vertically binary partitioned into an upper partition and a lower partition, each with a vertical to horizontal aspect ratio of 2:1.

[0127] In some other examples, the ternary partitioning scheme can be used to partition the basic block or any intermediate block, such as Fig.13 The ternary pattern can be Fig.13 The vertical implementation shown in 1302, or as Fig.13 1304 is shown as a horizontal implementation. Although whether vertical or horizontal, Fig.13 The example split ratios in are all shown as 1:2:1, but other ratios can also be predefined. In some implementations, two or more different ratios can be predefined. This ternary partitioning scheme can be used to complement the quadtree or binary partitioning structure because this ternary tree partitioning can capture objects located at the center of the block in one continuous partition, while the quadtree and binary tree always split along the center of the block, thereby dividing the object into separate partitions. In some implementations, in order to avoid additional transformations, the width and height of the partitions of the example ternary tree are always powers of 2.

[0128] The above partitioning schemes can be combined in any way at different partitioning levels. As an example, the above quadtree and binary partitioning schemes can be combined to partition basic blocks into a quadtree-binary-tree (QTBT) structure. In such a scheme, basic blocks or intermediate blocks / partitions can be quadtree split or binary split, if specified, subject to a set of predefined conditions. A specific example is Fig.14 As shown. Fig.14 In the example of , the basic block is first split into four partitions by a quadtree, as shown in 1402, 1404, 1406 and 1408. Thereafter, each of the resulting partitions is either split into four partitions by a quadtree (e.g., 1408), or is binary split into two further partitions at the next level (e.g., horizontally or vertically, such as 1402 or 1406, both of which are symmetrical), or is not split (e.g., 1404). For square partitions, binary or quadtree splitting can be recursively performed, as shown in the overall example partitioning pattern of 1410 and the corresponding tree structure / representation in 1420, where solid lines represent quadtree splitting and dashed lines represent binary splitting. A flag can be used for each binary split node (non-leaf binary partition) to indicate whether the binary split is horizontal or vertical. For example, as shown in 1420, consistent with the partition structure of 1410, a flag "0" can represent a horizontal binary split and a flag "1" can represent a vertical binary split. For quadtree-split partitions, there is no need to indicate the split type, since quadtree splits always split a block or partition horizontally and vertically to produce 4 sub-blocks / partitions of equal size. In some implementations, a flag of "1" may indicate a horizontal binary split, and a flag of "0" may indicate a vertical binary split.

[0129] In some example implementations of QTBT, the quadtree and binary splitting rule set may be represented by the following predefined parameters and corresponding functions associated therewith:

[0130] -CTU size: the root node size of the quadtree (the size of the basic block)

[0131] -MinQTSize: Minimum allowed quadtree leaf node size

[0132] -MaxBTSize: Maximum allowed binary tree root node size

[0133] -MaxBTDepth: Maximum allowed binary tree depth

[0134] -MinBTSize: The minimum allowed binary tree leaf node size

[0135] In some example implementations of the QTBT partition structure, the CTU size can be set to 128×128 luma samples, and two corresponding blocks of 64×64 chroma samples (when example chroma subsampling is considered and used), MinQTSize can be set to 16×16, MaxBTSize can be set to 64×64, MinBTSize (for width and height) can be set to 4×4, and MaxBTDepth can be set to 4. Quadtree partitioning can be first applied to the CTU to generate quadtree leaf nodes. Quadtree leaf nodes can have sizes from their minimum allowed size of 16×16 (i.e., MinQTSize) to 128×128 (i.e., the CTU size). If the node is 128×128, it will not be split first through the binary tree because its size exceeds the MaxBTSize (i.e., 64×64). Otherwise, nodes that do not exceed MaxBTSize can be partitioned through the binary tree. Fig.14 In the example, the basic block is 128×128. According to the predefined set of rules, the basic block can only be quadtree split. The partition depth of the basic block is 0. Each of the four partitions obtained is 64x64, not exceeding MaxBTSize, and can be further quadtree or binary tree split at level 1. This process continues. When the binary tree depth reaches MaxBTDepth (i.e. 4), further splitting can be ignored. When the width of the binary tree node is equal to MinBTSize (i.e. 4), further horizontal splitting can be ignored. Similarly, when the height of the binary tree node is equal to MinBTSize, further vertical splitting is not considered.

[0136] In some example implementations, the above-mentioned QTBT scheme can be configured to support the flexibility of having the same QTBT structure or separate QTBT structures for luma and chroma. For example, for P and B slices, the luma and chroma CTBs in one CTU can share the same QTBT structure. However, for I slices, the luma CTB can be partitioned into CBs by the QTBT structure, and the chroma CTB can be partitioned into chroma CBs by another QTBT structure. This means that a CU can be used to refer to different color channels in an I slice, for example, an I slice can consist of coding blocks of a luma component or coding blocks of two chroma components, and a CU in a P or B slice can consist of coding blocks of all three color components.

[0137] In some other implementations, the QTBT scheme can be supplemented with the above-mentioned ternary scheme. Such an implementation can be referred to as a multi-type tree (MTT) structure. For example, in addition to the binary split of the node, one can choose Fig.13 In some implementations, only square nodes can be ternary split. An additional flag can be used to indicate whether the ternary partition is horizontal or vertical.

[0138] Designs of two-level or multi-level trees, such as the QTBT implementation and the QTBT implementation supplemented by ternary splitting, may be motivated primarily by reducing complexity. In theory, the complexity of traversing the tree is T D , where T represents the number of split types, and D is the depth of the tree. A tradeoff can be made by using multiple types (T) while reducing the depth (D).

[0139] In some implementations, CB can be further partitioned. For example, for the purpose of intra-frame or inter-frame prediction during the encoding and decoding process, CB can be further partitioned into multiple prediction blocks (PBs). In other words, CB can be further divided into different sub-partitions, in which separate prediction decisions / configurations can be made. In parallel, in order to depict the level of transformation or inverse transformation of video data, CB can be further partitioned into multiple transform blocks (TBs). The partitioning schemes of CB to PB and TB can be the same or different. For example, each partitioning scheme can be performed using its own process based on various features of video data, for example. In some example implementations, PB and TB partitioning schemes can be independent. In some other example implementations, PB and TB partitioning schemes and boundaries can be related. In some implementations, for example, TB can be partitioned after PB partitioning, and specifically, each PB can be further partitioned into one or more TBs after being determined after the partitioning of the coding block. For example, in some implementations, PB can be split into one, two, four or other number of TBs.

[0140] In some implementations, in order to partition the basic block into coding blocks and further partition into prediction blocks and / or transform blocks, the luma channel and the chroma channel may be processed differently. For example, in some implementations, for the luma channel, the coding block may be partitioned into prediction blocks and / or transform blocks, while for the chroma channel, the coding block may not be partitioned into prediction blocks and / or transform blocks. Therefore, in such an implementation, the transformation and / or prediction of the luma block may be performed only at the coding block level. For another example, the minimum transform block size of the luma channel and the chroma channel may be different, for example, the coding block of the luma channel may be partitioned into a smaller transform and / or prediction block than the chroma channel. For yet another example, the maximum depth of partitioning the coding block into transform blocks and / or prediction blocks may be different between the luma channel and the chroma channel, for example, the coding block of the luma channel may be partitioned into a deeper transform block and / or prediction block than the chroma channel. For a specific example, a luma coding block may be partitioned into transform blocks of multiple sizes, which may be represented by recursive partitioning down to a maximum of 2 levels, and may allow transform block shapes such as square, 2:1 / 1:2, and 4:1 / 1:4, and transform block sizes from 4×4 to 64×64. However, for chroma blocks, only the largest possible transform block specified for the luma block may be allowed.

[0141] In some example implementations for partitioning a coding block into PBs, the depth, shape, and / or other characteristics of the PB partitions may depend on whether the PB is intra-coded or inter-coded.

[0142] The partitioning of coding blocks (or prediction blocks) into transform blocks can be implemented in various example schemes, including but not limited to recursively or non-recursively quadtree splitting and predetermined pattern splitting, and additionally considering transform blocks at the boundaries of coding blocks or prediction blocks. In general, the resulting transform blocks may be at different split levels, may not have the same size, and may not need to be square in shape (e.g., they may be rectangular with certain allowed sizes and aspect ratios). The following will be combined with Fig.15 , 16 and 17 further describe more examples in detail.

[0143] However, in some other implementations, the CB obtained via any of the above-mentioned partitioning schemes may be used as a basic or minimum coding block for prediction and / or transformation. In other words, no further splitting is performed for the purpose of performing inter-frame prediction / intra-frame prediction and / or transformation purposes. For example, the CB obtained from the above-mentioned QTBT scheme can be directly used as a unit for prediction. Specifically, this QTBT structure eliminates the concept of multiple partition types, that is, it eliminates the separation of CU, PU and TU, and supports greater flexibility in the CU / CB partition shape as described above. In this QTBT block structure, the CU / CB can be square or rectangular in shape. The leaf nodes of this QTBT are used as units of prediction and transformation processing without any further partitioning. This means that in this exemplary QTBT coding block structure, the CU, PU and TU have the same block size.

[0144] The various CB partitioning schemes described above and further partitioning of CB into PB and / or TB (excluding PB / TB partitioning) may be combined in any manner.The following specific implementations are provided as non-limiting examples.

[0145] A specific example implementation of coding block and transform block partitioning is described below. In such an exemplary implementation, recursive quadtree splitting or the above-mentioned predefined splitting patterns (e.g. Fig. 9 and 10) is split into coding blocks. At each level, it can be determined by local video data characteristics whether to continue to perform further quadtree splitting on a specific partition. The resulting CB can be at various quadtree splitting levels and have various sizes. The decision on whether to use inter-frame (time) or intra-frame (space) prediction to encode the picture area can be made at the CB level (or the CU level for all three color channels). Each CB can be further split into one, two, four or other number of PBs according to a predefined PB splitting type. Within a PB, the same prediction process can be applied, and relevant information can be sent to the decoder based on the PB. After obtaining the residual block by applying a prediction process based on the PB splitting type, the CB can be partitioned into TBs according to another quadtree structure of the coding tree similar to the CB. In this specific implementation, the CB or TB can be, but not necessarily limited to, a square. In addition, in this specific example, for inter-frame prediction, the PB can be a square or a rectangle, and for intra-frame prediction, the PB can be only a square. The coding block can be split into, for example, four square TBs. Each TB can be further recursively split (using quadtree splitting) into smaller TBs, called residual quadtrees (RQTs).

[0146] Another example implementation for partitioning a basic block into CBs, PBs, and / or TBs is described further below. Fig. 9 or Fig.10 For the multiple partition unit types shown, a quadtree with a nested multi-type tree can be used, which uses a binary and ternary split partitioning structure (for example, a QTBT as described above or a QTBT with a ternary split). The separation of CB, PB, and TB can be abandoned (i.e., partitioning CB into PB and / or TB, and partitioning PB into TB) unless a CB is required that is too large for the maximum transform length, where such a CB may need to be further split. The example partitioning scheme can be designed to support greater flexibility in the shape of CB partitions, so that both prediction and transformation can be performed at the CB level without further partitioning. In this coding tree structure, the shape of the CB can be square or rectangular. Specifically, the coding tree block (CTB) can be first partitioned by a quadtree structure. Then, the quadtree leaf nodes can be further partitioned by a nested multi-type tree structure. An example of a nested multi-type tree structure using binary or ternary splitting is shown in FIG. Fig.11 shown. Specifically, Fig.11The exemplary multi-type tree structure includes four split types, namely vertical binary split (SPLIT_BT_VER) (1102), horizontal binary split (SPLIT_BT_HOR) (1104), vertical ternary split (SPLIT_TT_VER) (1106) and horizontal ternary split (SPLIT_TT_HOR) (1108). The CB then corresponds to the leaves of the multi-type tree. In this example implementation, unless the CB is too large for the maximum transform length, the partition is used for prediction and transform processing without any further partitioning. This means that in most cases, in a quadtree with a nested multi-type tree coding block structure, the CB, PB, and TB have the same block size. An exception occurs when the maximum supported transform length is less than the width or height of the color component of the CB. In some implementations, in addition to the binary or ternary split, Fig.11 The nested pattern can also include quadtree splits.

[0147] Fig.12 A specific example of a quadtree with a nested multi-type tree coding block structure for block partitioning of a basic block (including quadtree, binary and ternary split options) is shown. In more detail, Fig.12 The basic block 1200 is shown to be quadtree-split into four square partitions 1202, 1204, 1206, and 1208. For each quadtree-split partition, it is decided to further use Fig.11 The multi-type tree structure and quadtree are further split. Fig.12 In the example, partition 1204 is not further split. Partitions 1202 and 1208 each use another quadtree split. For partition 1202, the second-level quadtree-splits the upper left, upper right, lower left, and lower right partitions using the third-level quadtree split, Fig.11 Horizontal binary split 1104, no split and Fig.11 The horizontal ternary split 1108 of the partition 1208 is performed using another quadtree split, and the second level quadtree-splits the upper left, upper right, lower left and lower right partitions respectively using Fig.11 The third level split of the vertical ternary split 1106, no split, no split and Fig.11 Horizontal binary split 1104. According to Fig.11 The horizontal binary split 1104 and the horizontal ternary split 1108 further split the two sub-partitions of the third level upper left partition 1208. Partition 1206 adopts the second level split mode, which follows Fig.11 The vertical binary split 1102 is divided into two partitions, which are divided into two partitions according to Fig.11 The horizontal ternary split 1108 and vertical binary split 1102 are further split at the third level. Fig.11's horizontal binary split 1104, a fourth level split is further applied to one of them.

[0148] For the specific example above, the maximum luma transform size may be 64×64, and the maximum supported chroma transform size may be different, e.g. 32×32 for luma. Fig.12 The example CB in the example is usually not further split into smaller PBs and / or TBs, but when the width or height of the luminance coding block or the chrominance coding block is larger than the maximum transform width or height, the luminance coding block or the chrominance coding block may be automatically split in the horizontal and / or vertical directions to meet the transform size limit in that direction.

[0149] In the above specific example for partitioning basic blocks into CBs, and as described above, the coding tree scheme can support the ability for luma and chroma to have separate block tree structures. For example, for P and B slices, the luma and chroma CTBs in one CTU can share the same coding tree structure. For example, for I slices, luma and chroma can have separate coding block tree structures. When a separate block tree structure is applied, the luma CTB can be partitioned into luma CBs through one coding tree structure, and the chroma CTB can be partitioned into chroma CBs through another coding tree structure. This means that a CU in an I slice can consist of coding blocks of a luma component or coding blocks of two chroma components, and a CU in a P or B slice always consists of coding blocks of all three color components unless the video is monochrome.

[0150] When a coding block is further partitioned into multiple transform blocks, the transform blocks therein can be ordered in the bitstream in various orders or scanning modes. Example implementations for partitioning a coding block or prediction block into transform blocks and the encoding order of transform blocks are further described in detail below. In some example implementations, as described above, transform partitioning can support transform blocks of multiple shapes, such as 1:1 (square), 1:2 / 2:1, and 1:4 / 4:1, with transform block sizes ranging from, for example, 4×4 to 64×64. In some implementations, if the coding block is less than or equal to 64×64, the transform block partitioning can be applied only to the luma component, so that for the chroma block, the transform block size is the same as the coding block size. Otherwise, if the coding block width or height is greater than 64, the luma and chroma coding blocks can be implicitly split into multiples of min(W, 64)×min(H, 64) and min(W, 32)×min(H, 32) transform blocks, respectively.

[0151] In some example implementations of transform block partitioning, for intra and inter coding blocks, the coding block may be further partitioned into multiple transform blocks with a partition depth of up to a predetermined number of levels (e.g., 2 levels). The transform block partition depth and size may be associated. For some example implementations, the mapping from the transform size of the current depth to the transform size of the next depth is as shown in Table 1 below.

[0152] Table 1: Change partition size settings

[0153]

[0154] Based on the example mapping of Table 1, for a 1:1 square block, the next level transform split can create four 1:1 square sub-transform blocks. For example, the transform partition can stop at 4x4. Therefore, the transform size of 4×4 at the current depth corresponds to the same size 4×4 at the next depth. In the example of Table 1, for a 1:2 / 2:1 non-square block, the next level transform split can create two 1:1 square sub-transform blocks, and for a 1:4 / 4:1 non-square block, the next level transform split can create two 1:2 / 2:1 sub-transform blocks.

[0155] In some example implementations, for the luma component of an intra-coded block, additional restrictions may be applied with respect to the transform block partitioning. For example, for each level of transform partitioning, all sub-transform blocks may be constrained to have equal size. For example, for a 32x16 coding block, a level 1 transform split creates 2 16x16 sub-transform blocks and a level 2 transform split creates 8 8x8 sub-transform blocks. In other words, the second level split must be applied to all first level sub-blocks to keep the transform unit sizes equal. Fig.15 1504 shows an example of transform block partitioning for intra-coded square blocks according to Table 1 and the coding order indicated by the arrows. Specifically, 1502 shows a square coding block. 1504 shows the first-level splitting into 4 equal-sized transform blocks according to Table 1, and the coding order is indicated by the arrows. 1506 shows the second-level splitting of all first-level equal-sized blocks into 16 equal-sized transform blocks according to Table 1, and the coding order is indicated by the arrows.

[0156] In some example implementations, the above-mentioned restrictions on intra-frame coding may not apply to the luminance component of the inter-frame coded block. For example, after the first level transform splitting, any of the sub-transform blocks can be further independently split into more than one level. Therefore, the resulting transform blocks can have the same or different sizes. Fig.16 An example of splitting an inter-frame coded block into transform blocks with their coding order is shown. Fig.16In the example of FIG. 1602, the inter-frame coded block 1602 is split into two levels of transform blocks according to Table 1. In the first level, the inter-frame coded block is split into four transform blocks of equal size. Then, only one of the four transform blocks (not all) is further split into four sub-transform blocks, resulting in a total of 7 transform blocks with two different sizes, as shown in 1604. The example coding order of these 7 transform blocks is as follows: Fig.16 As shown by the arrow in 1604.

[0157] In some example implementations, for chroma components, some additional restrictions on transform blocks may be applied. For example, for chroma components, the transform block size may be as large as the coding block size, but not smaller than a predefined size, such as 8×8.

[0158] In some other example implementations, for coding blocks with width (W) or height (H) greater than 64, both luma and chroma coding blocks may be implicitly split into multiples of min(W, 64)×min(H, 64) and min(W, 32)×min(H, 32) transform units, respectively. Here, in the present disclosure, "min(a, b)" may return the smaller value between a and b.

[0159] Fig.17 Another alternative example scheme for partitioning a coding block or prediction block into transform blocks is further shown. Fig.17 As shown, instead of using recursive transform partitioning, a predefined set of partition types can be applied to the coding block according to the transform type of the coding block. Fig.17 In the specific example shown, one of six example partition types may be applied to split a coding block into various numbers of transform blocks. This scheme for generating transform block partitions may be applied to either a coding block or a prediction block.

[0160] In more detail, Fig.17 The partition scheme of provides up to 6 example partition types for any given transform type (transform type refers to, for example, the type of main transform, such as ADST and others). In this scheme, each coding block or prediction block can be assigned a transform partition type based on, for example, rate-distortion cost. In an example, the transform partition type assigned to a coding block or prediction block can be determined based on the transform type of the coding block or prediction block. A specific transform partition type can correspond to a transform block split size and mode, such as Fig.17 As shown in the 6 transform partition types in . The correspondence between various transform types and various transform partition types can be predefined. An example is shown below, where the uppercase label indicates the transform partition type that can be assigned to the coding block or prediction block based on the rate-distortion cost:

[0161] PARTITION_NONE: Allocate a transform size equal to the block size.

[0162] PARTITION_SPLIT: Allocate a transform size whose width is 1 / 2 of the width of the block size and whose height is 1 / 2 of the height of the block size.

[0163] PARTITION_HORZ: Allocate a transform size with the same width as the block size and a height that is 1 / 2 of the block size's height.

[0164] PARTITION_VERT: Allocate a transform size whose width is 1 / 2 the width of the block size and whose height is the same as the height of the block size.

[0165] PARTITION_HORZ4: Allocates a transform size whose width is the same as the width of the block size and whose height is 1 / 4 of the height of the block size.

[0166] PARTITION_VERT4: Allocates a transform size whose width is 1 / 4 of the width of the block size and whose height is the same as the height of the block size.

[0167] In the above example, if Fig.17 The transform partition types shown all include a uniform transform size for the partitioned transform blocks. This is just an example and is not intended to limit the present invention. In some other implementations, a mixed transform block size can be used for the partitioned transform blocks in a specific partition type (or mode).

[0168] A video block (PB or CB, also referred to as a PB when not further partitioned into multiple prediction blocks) can be predicted in various ways, rather than directly encoded, thereby taking advantage of various correlations and redundancies in the video data to improve compression efficiency. Accordingly, this prediction can be performed in various modes. For example, a video block can be predicted by intra-frame prediction or inter-frame prediction. In particular, in the inter-frame prediction mode, a video block can be predicted by one or more other reference blocks or inter-frame predictor blocks from one or more other frames through single reference or composite reference inter-frame prediction. In order to implement inter-frame prediction, a reference block can be specified by its frame identifier (the temporal position of the reference block) and a motion vector indicating the spatial offset between the current block being encoded or decoded and the reference block (the spatial position of the reference block). The reference frame identifier and motion vector can be signaled in the bitstream. The motion vector as a spatial block offset can be directly signaled, or can be predicted by another reference motion vector or the predictor motion vector itself. For example, the current motion vector may be predicted directly by a reference motion vector (e.g., of a candidate neighboring block), or by a combination of a reference motion vector and a motion vector difference (MVD) between the current motion vector and the reference motion vector. The latter may be referred to as a merge mode with motion vector difference (MMVD). In a bitstream, a reference motion vector may be identified as a pointer to, for example, a spatial neighboring block of the current block or a temporally adjacent but spatially co-located block.

[0169] In some other example implementations, intra-block copy (IBC) prediction may be employed. In IBC, a current block in a current frame may be predicted using another block in the current frame (rather than a different frame in time, hence the term "intra") in conjunction with a block vector (BV) indicating the offset of the position of the intra predictor or reference block relative to the position of the block being predicted. The position of the coding block may be represented by, for example, the pixel coordinates of the upper left corner relative to the upper left corner of the current frame (or slice). Thus, the IBC mode uses similar inter-frame prediction concepts within the current frame. For example, a BV may be predicted by other reference BVs directly or in conjunction with the BV difference between the current BV and the reference BV, similar to using a reference MV and MV difference to predict an MV in inter-frame prediction. IBC helps provide improved codec efficiency, particularly for encoding and decoding video frames with screen content, for example, the screen content contains a large number of repetitive patterns, such as text information, where the same text segments (letters, symbols, words, phrases, etc.) appear in different parts of the same frame and can be used to predict each other.

[0170] In some implementations, IBC can be considered as a separate prediction mode in addition to the normal intra-frame prediction mode and the normal inter-frame prediction mode. Therefore, the prediction mode of a specific block can be selected and the selected prediction mode can be signaled in three different prediction modes: intra-frame prediction, inter-frame prediction and IBC mode. In these implementations, flexibility can be established in each of these modes to optimize the encoding and decoding efficiency of each of these modes. In some other implementations, similar motion vector determination, reference and encoding and decoding mechanisms can be used to regard IBC as a sub-mode or branch within the inter-frame prediction mode. In such an implementation (integrating inter-frame prediction mode and IBC mode), in order to coordinate the general inter-frame prediction mode and IBC mode, the flexibility of IBC may be limited to a certain extent. However, this implementation is not too complicated, and IBC can still be used to improve the encoding and decoding efficiency of video frames characterized by screen content, for example. In some example implementations, the inter-frame prediction mode can be extended to support IBC using existing pre-specified mechanisms for separate inter-frame prediction modes and intra-frame prediction modes.

[0171] The selection of these prediction modes can be made at various levels, including but not limited to sequence level, frame level, picture level, slice level, CTU level, CT level, CU level, CB level or PB level. For example, for the purpose of IBC, the decision on whether to adopt the IBC mode can be made at the CTU level and signaled. If the CTU is signaled to adopt the IBC mode, all coding blocks in the entire CTU can be predicted by IBC. In some other implementations, the IBC prediction can be determined at the super block (SB or super block) level. Each SB can be split into multiple CTUs or partitions in various ways (e.g., quadtree partitioning). Examples are further provided below.

[0172] Fig.18 An example brief description of a portion of a current frame containing multiple CTUs is shown from the perspective of a decoder. Each square (such as 1802) represents a CTU. The CTU size can be one of the various predefined sizes described in detail above, such as SB. Each CTU may include one or more coding blocks (or prediction blocks, for a particular color channel). CTUs masked with horizontal lines represent those CTUs that have been reconstructed. CTU 1804 represents the current CTU being reconstructed. In the current CTU 1804, the coding blocks masked with horizontal lines represent those blocks that have been reconstructed in the current CTU, the coding blocks 1806 masked with diagonal lines are currently being reconstructed, and the unmasked coding blocks in the current CTU 1804 are waiting to be reconstructed. Other unmasked CTUs have not yet been processed.

[0173] like Fig.18As shown by the example arrow in FIG. 1 , the position or offset of the reference block (relative to the current block) used in the IBC to predict the current coding block can be indicated by BV. For example, BV can indicate the reference block (in Fig.18 The position difference between the upper left corner of the block marked as "Ref" in the figure and the upper left corner of the current block. Fig.18 The above description is illustrated using CTU as the basic IBC unit. The basic principles apply to implementations using SB as the basic IBC unit. In such implementations, each super block may be divided into multiple CTUs, and each CTU may be further divided into multiple coding blocks, as described in more detail below.

[0174] As further disclosed in more detail below, depending on the position of the reference CTU / SB for IBC relative to the current CTU / SB, the reference CTU / SB may be referred to as a local CTU / SB or a non-local CTU / SB. A local CTU / SB may refer to a CTU / SB that overlaps with the current CTU / SB, or to a CTU / SB that is close to the current CTU / SB and has been reconstructed (e.g., a left-neighboring CTU / SB of the current CTU / SB). A non-local CTU / SB may refer to a CTU / SB that is farther away from the current CTU / SB. When performing IBC prediction of the current coding block, any or all of the local CTU / SB and the non-local CTU / SB may be searched for a reference block. The specific manner of implementing IBC may depend on whether the reference CTU / SB is local or non-local, because the on-chip and off-chip storage management of the reconstructed samples (e.g., an off-chip picture buffer (DPB) and / or on-chip memory) for reference to a local or non-local CTU / SB may be different. For example, the reconstructed local CTU / SB samples may be suitable for storage in an on-chip memory of an encoder or decoder for IBC. For example, the reconstructed non-local CTU / SB samples may be stored in an off-chip DPB memory or an external memory.

[0175] In some implementations, the locations of reconstructed blocks that can be used as reference blocks for the current coding block 1804 can be restricted. This restriction can be the result of various factors and can depend on whether IBC is an integrated part of the general inter-frame prediction mode, a special extension of the inter-frame prediction mode, or a separate and independent IBC mode. In some examples, only the current reconstructed CTU / SB samples can be searched to identify the IBC reference block. In some other examples, such as Fig.18As shown in the thick dashed box 1808, the current reconstructed CTU / SB sample and another adjacent reconstructed CTU / SB sample (e.g., the left adjacent CTU / SB) can be used for reference block search and selection. For such an implementation, only the local reconstructed CTU / SB samples can be used for IBC reference block search and selection. In some other examples, due to various other reasons, some CTU / SB may not be available for IBC reference block search and selection. For example, in Fig.18 The CTUs / SBs 1810 marked with cross lines in FIG. 1804 may not be used for searching and selecting reference blocks for the current block 1804 because they may be used for special purposes (eg, wavefront parallel processing), as described further below.

[0176] In some implementations, such as Fig.18 As shown, the area formed by the thick dashed box 1808 may be referred to as a local search area. The samples in the local search area may be stored in an on-chip memory.

[0177] In some implementations, when IntraBC is enabled, the loop filter is disabled, including the deblocking filter, the constrained directional enhancement filter (CDEF), and the loop restoration (LR). By doing so, a second picture buffer dedicated to enabling / supporting IntraBC can be avoided.

[0178] In some implementations, employing parallel decoding (i.e., decoding more than one coding block at the same time) may result in restrictions on the number of reconstructed CTUs / SBs that are allowed to be used to provide IBC reference blocks or reference samples. Fig.19 In the example shown, each block represents a CTU / SB. Parallel decoding can be implemented, where multiple CTU / SBs in multiple consecutive rows and every other column (every two columns) can be reconstructed in parallel, such as Fig.19 As shown in the CTU / SB masked with diagonal lines. The other CTU / SB masked with horizontal lines have been reconstructed, and the unmasked CTU / SB has not yet been constructed. Through this parallel processing, for the current parallel processed CTU / SB with the upper left coordinate (x0, y0), the reconstructed sample at (x, y) can be accessed in the IBC to predict the current CTU / SB only when the vertical coordinate y is less than y0 and the horizontal coordinate x is less than x0+2(y0-y). Therefore, the already constructed CTU / SB masked with horizontal lines can be used as a reference for the current block processed in parallel. Note that coordinate units such as (x0, y0) and (x, y) may include pixels, blocks (e.g., SBs), etc.

[0179] In some implementations, the write-back latency of writing immediately reconstructed samples to the off-chip DPB may impose further restrictions on the CTUs / SBs available to provide IBC reference samples for the current block, especially when the off-chip DPB is used to hold IBC reference samples. Fig. 20 An example is shown in Fig.19 Additional restrictions are imposed on top of those shown. Specifically, to allow for hardware write-back latency, IBC prediction may not access the immediate reconstruction area to search and select reference blocks. The number of immediate reconstruction areas that are restricted or prohibited may be 1 to n CTU / SBs, where n is a positive number that may be positively correlated with the duration of the write-back latency. Thus, in Fig.19 Above the specific parallel processing limit of , for the current CTU / SB (using diagonal line masking), if the coordinates of the upper left position of a current CTU / SB are (x0, y0), then if the vertical coordinate y is less than y0 and the horizontal coordinate is less than x0+2(y0-y)-D, the prediction at position (x, y) can be accessed through IBC, where D represents the number of immediate reconstruction areas (e.g., to the left of the current CTU / SB) that are restricted / prohibited from being used as IBC references. Fig. 20 These additional CTUs / SBs that are restricted from being IBC reference samples are shown for D=2 (in blocks, or 2x128 pixels in pixels when each block is a 128x128 SB). These additional CTUs / SBs that cannot be IBC references are indicated by backslash shading.

[0180] In some implementations, such as Fig. 20 As shown, a region formed by using blocks masked with horizontal lines may be referred to as a non-local search region, and samples in the region may be stored in an external memory.

[0181] In some implementations, also described in further detail below, both local search areas and non-local CTU / SB search areas may be used for IBC reference block search and selection. In addition, when on-chip memory is used, some restrictions on write-back latency in the restrictions on the availability of already constructed CTU / SB as IBC references may be relaxed or removed. In some further implementations, the use of local CTU / SB and non-local CTU / SB when they coexist may be different, due to, for example, different buffer management of reference blocks using on-chip memory or off-chip memory. These implementations are described in more detail in the following disclosure.

[0182] In some implementations, IBC can be implemented as an extension of the inter-frame prediction mode, in which the current frame is considered as a reference frame, so that blocks within the current frame can be used as prediction references. Such an IBC implementation can therefore follow the coding path for inter-frame prediction, even if the IBC process only involves the current frame. In such an implementation, the reference structure of the inter-frame prediction mode can be adapted to IBC, where the representation of the addressing mechanism for reference samples using BV can be similar to the motion vector (MV) in inter-frame prediction. Therefore, relying on a syntax structure and decoding process similar or identical to the inter-frame prediction mode based on the current frame as a reference frame, IBC can be implemented as a special inter-frame prediction mode.

[0183] In such an implementation, since IBC can be regarded as an inter-frame prediction mode, intra-frame prediction-only slices must become prediction slices that allow the use of IBC. In other words, intra-frame prediction-only slices will not be inter-frame predicted (because the intra-frame prediction mode will not call any inter-frame prediction processing path), so IBC will not be allowed for prediction in such intra-frame-only slices. When IBC is applicable, the encoder extends the reference picture list by one entry for a pointer to the current picture. Therefore, the current picture can occupy up to a picture-sized buffer of the shared decoded picture buffer (DPB). The signaling of using IBC can be implicit in the selection of reference frames in inter-frame prediction mode. For example, when the selected reference picture points to the current picture, if necessary and available, the coding unit will adopt IBC with a coding path similar to inter-frame prediction and a special IBC extension. In some specific implementations, in contrast to conventional inter-frame prediction, the reference samples in the IBC process may not be loop-filtered before being used for prediction. In addition, the corresponding reference current picture can be a long-term reference frame because it will be near the next frame to be encoded or decoded. In some implementations, to minimize memory requirements, the encoder can release the buffer immediately after reconstructing the current picture. When the filtered version of the reconstructed picture becomes a reference picture for subsequent frames in true inter-frame prediction, the encoder can fill it back into the DPB as a short-term reference, even though it may be unfiltered when used for IBC.

[0184] In the example implementation above, even though IBC may be merely an extension of the inter-frame prediction mode, IBC may be processed using several special processes that may deviate from normal inter-frame prediction. For example, IBC reference samples may also be unfiltered. In other words, reconstructed samples before in-loop filtering processes including deblocking filtering (DBF), sample adaptive offset (SAO) filtering, cross-component sample offset (CCSO) filtering, etc. may be used for IBC prediction, while the normal inter-frame prediction mode uses filtered samples for prediction. For another example, no luma sample interpolation for IBC may not be performed, and chroma sample interpolation may only be necessary when the chroma BV is non-integer when derived from the luma BV. For another example, when the chroma BV is non-integer and the reference block for IBC is near the boundary of the available area for IBC reference, the surrounding reconstructed samples may be outside the boundary to perform chroma interpolation. It is impossible to avoid this situation with a BV pointing to a line adjacent to the boundary.

[0185] In such an implementation, the prediction of the current block by IBC can reuse the prediction and coding mechanism of the inter prediction process, including using the reference BV to predict the current BV and, for example, additional BV differences. However, in some specific implementations, the luma BV can be implemented with integer resolution rather than fractional precision as in MV for conventional inter prediction.

[0186] In some implementations, Fig.18 All CTUs and SBs indicated by horizontal hatching in the figure can be used to search and select IBC reference blocks, except Fig.18 The two CTUs ( Fig.18 The image is then reconstructed using the cross-hatched lines in Figure 1 to allow for Wavefront Parallel Processing (WPP). Therefore, with some exceptions for parallel processing purposes, almost the entire area of ​​the current picture has been reconstructed.

[0187] In some other implementations, the area from which IBC reference blocks can be searched and selected can be limited to local CTU / SB. Fig.18Indicated by the thick dashed box 1808. In such an example, the CTU / SB to the left of the current CTU can be used as a reference sample area for IBC at the beginning of the reconstruction process of the current CTU. When such a local reference area is used, instead of allocating additional external memory space in the DPB, on-chip memory space can be allocated to hold the local CTU / SB for IBC reference. In some implementations, fixed on-chip memory can be used for IBC, thereby reducing the complexity of implementing IBC in the hardware architecture. Therefore, a dedicated IBC mode independent of normal inter-frame prediction can be implemented for utilizing on-chip memory, rather than simply being implemented as an extension of the inter-frame prediction mode.

[0188] For example, for each color component, the fixed on-chip memory size for storing local IBC reference samples (e.g., left CTU or SB) can be 128×128. In some implementations, the maximum CTU size can also be 128×128. In this case, the reference sample memory (RSM) can hold samples with a single CTU size. In some other alternative implementations, the CTU size can be smaller. For example, the CTU size can be 64x64. Therefore, the RSM can hold multiple (4 in this example case) CTUs at the same time. In some other implementations, the RSM can hold multiple SBs, each SB can include one or more CTUs, and each CTU can include multiple coding blocks.

[0189] In some implementations of local on-chip IBC reference, the on-chip RSM holds one CTU and a continuous update mechanism may be implemented for replacing the reconstructed samples of the left-neighboring CTU with the reconstructed samples of the current CTU. Fig.21 A simplified example of this continuous RSM update mechanism is shown at four intermediate times during the reconstruction process. Fig.21 In the example, the RSM has a fixed size to hold one CTU. The CTU may include implicit partitioning. For example, the CTU may be implicitly divided into four separate regions (e.g., quadtree partitioning). Each region may include multiple coding blocks. The size of the CTU may be 128×128, while for the example quadtree partitioning, the size of each example region or partition may be 64×64. The region / partition of the RSM shaded with horizontal lines in each intermediate time holds the corresponding reconstructed reference samples of the left adjacent CTU, and the region / partition shaded with vertical lines in gray holds the corresponding reconstructed reference samples of the current CTU. The coding block of the RSM shaded with diagonal lines indicates that the current coding block within the current region is being encoded / decoded / reconstructed.

[0190] As shown in 2102, at the first intermediate time representing the start of reconstruction of the current CTU, the RSM may include reconstructed reference samples of the left-neighboring CTU only for each of the four example regions. In the other three intermediate times, the reconstruction process gradually replaces the reconstructed reference samples of the left-neighboring CTU with the reconstructed samples of the current CTU. When the encoder processes the first coding block of the region / partition, the 64×64 region / partition in the RSM is reset. When the region of the RSM is reset, the region is considered to be blank and is considered to not hold any reconstructed reference samples for IBC (in other words, the region of the RSM is not yet ready to be used as IBC reference samples). When processing the corresponding current coding block in the region, the corresponding block in the RSM is filled with the reconstructed samples of the corresponding block of the current CTU to be used as reference samples of the IBC of the next current block, as Fig.21 As shown in FIG. 2 for intermediate times 2104, 2106 and 2108. Once the region / partition corresponding to the RSM has processed all coding blocks, the entire region is filled with the reconstructed samples of these current coding blocks as IBC reference samples, as shown in FIG. Fig.21 As shown in the area completely shaded by vertical lines at each intermediate time. Therefore, in the intermediate times 2104 and 2106, some areas / partitions in the RSM hold IBC reference samples from adjacent CTUs, some other areas / partitions completely hold reference samples from the current CTU, and some areas / partitions partially hold reference samples from the current CTU and are partially blank (the blank portion is not used for IBC reference as a result of the above-mentioned reset process). When the last area (e.g., the lower right area) is being processed, all other three areas will hold the reconstructed samples of the current CTU as reference samples for IBC, while the last area / partition partially holds the reconstructed samples of the corresponding coding blocks in the current CTU and is partially blank until the last coding block of the CTU is reconstructed, at which time the entire RSM holds the reconstructed samples of the current CTU and if it is also encoded in IBC mode, the RSM is ready for the next CTU.

[0191] Fig. 22 The implementation of the above-described continuous updating of the RSM in space at a specific intermediate time is shown, i.e., both the left neighboring CTU and the current CTU with the current coding block (block shaded by oblique shading) are shown. The reconstructed samples corresponding to these two CTUs, in the RSM and valid as IBC reference samples for the current coding block are shown by horizontal and vertical shading. At the specific reconstruction time in this example, in the RSM, the process has replaced the samples covered by the unshaded area in the left neighboring CTU with the area of ​​the current CTU shaded by vertical shading. The remaining valid samples from the neighboring CTU are shown as horizontal line shading.

[0192] In the example implementation above, when the fixed RSM size is the same as the CTU size, the RSM is implemented to contain one CTU. In some other implementations where the CTU size is smaller, the RSM may contain more than one CTU. For example, the size of the CTU may be 32x32, while the size of the fixed RSM may be 128x128. Therefore, the RSM may hold samples of 16 CTUs. Following the same basic RSM update principle described above, the RSM may hold 16 adjacent CTUs of the current 128×128 patch before being reconstructed. Once processing of the first coding block of the current 128×128 patch begins, the first 32×32 region in the RSM that is initially filled with reconstructed samples of one adjacent CTU may be updated as described above for an RSM that holds a single CTU. The remaining 15 32×32 regions contain 15 adjacent CTUs as reference samples for IBC. Once the CTU corresponding to the first 32×32 region of the current 128×128 tile being decoded is reconstructed, the first 32×32 region of the RSM is updated with the reconstructed samples of the CTU. Then, the CTU corresponding to the second 32×32 region of the current 128×128 tile can be processed and eventually updated with the reconstructed samples. This process continues until 16 32×32 regions of the RSM contain reconstructed samples for the current 128×128 tile (a total of 15 CTUs). The decoding process then proceeds to the next 128x128 tile.

[0193] In some other implementations, as Fig.21 and 22 As an extension of , the RSM can hold a set of adjacent CTUs. One current CTU is processed at a time, and the portion of the RSM holding the furthest adjacent CTU is updated with the reconstructed current CTU in the manner described above. For the next current CTU, similarly, the furthest adjacent CTU in the RSM is updated and replaced. Thus, multiple CTUs held in a fixed-size RSM are updated with a moving window of adjacent CTUs for IBC.

[0194] Fig.23 Another specific example implementation of local IBC using on-chip RSM is shown. In this example, the maximum block size of the IBC mode may be limited. For example, the largest IBC block may be 64x64. The on-chip RSM may be configured with a fixed size corresponding to a super block (SB), such as 128×128. Fig.23 The RSM implementation uses Fig.21 and Fig. 22 The implementation principle is similar to that of Fig.23 In , RSM can maintain multiple adjacent and / or current CTUs as IBC reference samples. Fig.23In the example of , the SB can be split by a quadtree. Accordingly, the RSM can be split by a quadtree into 4 regions or units, each of which is 64×64. Each of these regions can hold one or more coding blocks. Alternatively, each of these regions can hold one or more CTUs, and each CTU can hold one or more coding blocks. The coding order of the quadtree regions can be predefined. For example, the coding order can be top left, top right, bottom left, bottom right. Fig.23 The quadtree splitting of the SB is just an example. In some other alternative implementations, the SB can be split according to any other scheme. The RSM update implementation for local IBC described in this article is applicable to those alternative splitting schemes.

[0195] In this local IBC implementation, the local reference blocks that can be used for IBC prediction can be limited. For example, it may be required that the reference block and the current block should be in the same SB row. Specifically, the local reference block can only be located in the current SB or in an SB to the left of the current SB. Fig.23 The dashed arrow in shows an example current block predicted in IBC by another allowed coding block. When the current SB or the left SB is used for IBC reference, the reference sample update process in RSM can follow the above reset process. For example, when any of the 64×64 unit reference sample memories starts to be updated with the reconstructed samples from the current SB, the previously stored reference samples (from the left SB) in the entire 64×64 unit are marked as unavailable for generating IBC prediction samples, and it is gradually updated with the reconstructed samples of the current block.

[0196] Fig.23 5 example states of the RSM during local IBC decoding of the current SB in panel 2302 are shown. Again, in each example state, the area of ​​the RSM shaded with horizontal lines holds the corresponding reference samples of the corresponding quadtree area of ​​the left adjacent SB, and the area / partition shaded with vertical lines in gray holds the corresponding reference samples of the current SB. The coded block of the RSM shaded with diagonal lines indicates that the current coded block within the current quadtree area is being coded / decoded. At the beginning of the coding of each current SB, the RSM stores samples of the previously coded SB ( Fig.23 RSM state (0)). When the current block is located in one of the four 64×64 quadtree regions in the current SB, the corresponding region in the RSM is reset and used to store the samples of the current 64×64 coded region. In this way, the samples in each 64×64 quadtree region of the RSM are gradually updated by the samples in the current SB (state (1)-state (3)). When the current SB has been completely encoded, the entire RSM is filled with all the samples of the current SB (state (4)).

[0197] Fig.23 Each of the 64×64 regions in the panel 2302 is labeled with a spatially encoded sequence number. Sequence numbers 0-3 represent the 4 64×64 quadtree regions of the left neighbor SB, while sequence numbers 4-7 represent the 4 64×64 quadtree regions of the current SB panel. Fig.23 , panel 2304 further illustrates the Fig.23 RSM state (1), state (2) and state (3) of panel 2302, corresponding spatial distribution in the left adjacent and current SB of the reference sample in the 128x28 RSM. The shaded area without cross-hatching indicates the area with reconstructed samples in the RSM. The shaded area with cross-hatching indicates the area in the RSM with the reconstructed samples of the left SB reset (and therefore cannot be used as reference samples for local IBC).

[0198] The encoding order of 64×64 regions and the corresponding RSM update order can follow the horizontal scan (as shown above Fig.23 Horizontal scanning starts from the upper left, goes to the upper right, lower left, and lower right. Vertical scanning starts from the upper left, goes to the lower left, upper right, and lower right. Fig.24 Panels 2402 and 2404 of FIG. 1 show the left adjacent SB and current SB reference sample update process for horizontal scanning and vertical scanning, respectively, for comparison when reconstructing each of the four 64x64 regions of the current SB. Fig.24 In the figure, the 64x64 area shaded with horizontal lines and without cross lines represents the area with samples that can be used for IBC. The area shaded with horizontal lines and with cross lines represents the area of ​​the left adjacent SB that has been updated to the corresponding reconstructed samples of the current SB. The unshaded area represents the unprocessed area of ​​the current SB. The block shaded with diagonal lines represents the current coding block being processed.

[0199] like Fig.24 As shown, according to the position of the current coding block relative to the current SB, the following restrictions on the reference blocks of IBC may be applied.

[0200] If the current block falls into the upper left 64×64 area of ​​the current SB, then in addition to the samples already reconstructed in the current SB, it can also refer to the reference samples in the lower right, lower left, and upper right 64×64 blocks of the left SB, such as Fig.24 2412 (for horizontal scanning) and 2422 (for vertical scanning) are shown.

[0201] If the current block falls into the upper right 64×64 block of the current SB, then in addition to the samples that have been reconstructed in the current SB, if the luma sample at (0, 64) relative to the current SB has not been reconstructed, the current block can also refer to the reference samples in the lower left 64×64 block and the lower right 64×64 block of the left SB ( Fig.24 Otherwise, the current block can also refer to the reference sample in the lower right 64x64 block of the left SB ( Fig.24 2426) for IBC.

[0202] If the current block falls into the lower left 64×64 block of the current SB, then in addition to the samples that have been reconstructed in the current SB, if the brightness position (64, 0) relative to the current SB has not been reconstructed, the current block can also refer to the reference samples in the upper right 64×64 block and the lower right 64×64 block of the left SB ( Fig.24 Otherwise, the current block can also refer to the left SB ( Fig.24 The reference samples in the lower right 64x64 block of 2416) are used for IBC.

[0203] If the current block falls into the lower right 64x64 block of the current SB, it can only refer to the samples that have been reconstructed in the current SB ( Fig.24 2418 and 2428) for IBC.

[0204] As described above, in some example implementations, either or both of local and non-local CTU / SB based can be used for IBC reference block search and selection. In addition, when on-chip RSM is used for local reference, some restrictions on write-back latency in the restrictions on the availability of already constructed CTU / SB as IBC reference can be relaxed or removed. Such implementations can be applied regardless of whether parallel decoding is adopted.

[0205] Fig.25 An example implementation of local and non-local reference CTU / SBs that can be used for IBC is shown, where again, each square represents a CTU / SB. CTU / SBs shaded with diagonal lines represent the current CTU / SB (marked as "0"), while CTU / SBs shaded with horizontal lines (marked as "1"), CTU / SBs shaded with vertical lines (marked as "2"), and CTU / SBs shaded with reverse diagonal lines (marked as "3") represent areas that have been constructed. Unshaded CTU / SBs represent areas that have not yet been reconstructed. Assume that a similar Fig.19 and 20 The CTU / SB shaded with vertical lines ("2") and reverse slashes ("3") represent sample regions that are typically restricted to outside the IBC reference of the current CTU / SB due to write-back latency to the DPB when only off-chip memory is used for IBC reference (see Fig. 20 ). When using on-chip RSM, Fig. 20One or more of the restricted areas may be referenced directly from the RSM, so there may be no need to restrict them out. The number of restricted areas that can now be accessed through the RSM for IBC reference may depend on the size of the RSM. Fig.25 In the example of , it is assumed that the RSM can hold one CTU / SB and the above RSM update mechanism is used. Therefore, the left neighboring CTU / SB shaded with a vertical line and marked as "2" can be used for local reference. Then, the RSM holds samples from the left CTU / SB and the current CTU / SB. Therefore, in Fig.25 In the example of FIG. 1 , the search area available for non-local IBC reference blocks includes CTUs / SBs marked as “1” (search area 1 (SA1), or non-local search area), the search area available for local IBC reference blocks includes CTUs / SBs marked as “2” and “0” (the search area may be referred to as search area 2 (SA2), or local search area), and the restricted-out / forbidden area for IBC reference blocks includes CTUs / SBs marked as “3” due to write-back latency. In some other implementations, using an on-chip RSM size sufficient to hold the entire restricted CTU / SB, all of these potential restricted areas may be included in the RSM for local reference. For example, left neighboring blocks marked as “2” and “3” may be included in the local search area.

[0206] In some other implementations, only the current CTU / SB or a portion of the current CTU / SB marked as "0" may be included in the RSM for local reference.

[0207] In some example implementations, the samples in SA1 may be stored in external memory.

[0208] In some example implementations, the samples in SA2 may be stored in on-chip memory.

[0209] In some example implementations, the external memory and the on-chip memory have different hardware characteristics, such as access speed, access clock, access bandwidth, etc.

[0210] When performing Intra Block Copy (IntraBC) prediction, a special case may occur when the block vector points to a block that is partially located in SA1 and partially located in SA2. In this special case, further restrictions or processing may need to be applied before using the block as a prediction block.

[0211] In some example implementations, in this special case, the block pointed to by the block vector is not allowed or excluded from being used as a prediction block for IntraBC.

[0212] Fig.26Various example blocks pointed to by respective block vectors are shown. Block A is not allowed to be used as a prediction block because it overlaps both SA1 and SA2; Block B is allowed to be used as a prediction block because it is completely contained in SA2; and Block C is allowed to be used as a prediction block because it is completely contained in SA1.

[0213] In some example implementations, if the block vector of IntraBC points to a block (denoted by B) that is partially located in SA1 and partially located in SA2, it is suggested to replace samples in B that overlap with SA1 or replace samples in B that overlap with SA2. The replacement of samples can be done by extending the boundary samples that can be used for prediction. For example, to replace samples in B that overlap with SA1, boundary samples in SA2 can be used; to replace samples in B that overlap with SA2, boundary samples in SA1 can be used.

[0214] In some example implementations, the overlap region size may be used to determine which overlap region sample replacement should be applied to. If the overlap region size between B and SA1 is greater than the overlap region size between B and SA2, samples located in the overlap portion between B and SA2 are replaced, and vice versa.

[0215] In some example implementations, the number of samples may be used to determine to which overlapping region sample replacement should be applied. Denote the number of samples covered by the overlapping portion between B and SA1 as S1, and the number of samples covered by the overlapping portion between B and SA2 as S2. If S1 is greater than S2 multiplied by a weighting factor (t1) (i.e., S1>S2*t1), then replace the samples in the overlapping portion between B and SA2, where t1 may be predefined or dynamically signaled. Similarly, if S2 is greater than S1 multiplied by a weighting factor (t2), then replace the samples in the overlapping portion between B and SA1, where t2 may be predefined or dynamically signaled.

[0216] In some example implementations, when sample replacement is applied to the overlap between B and SA1, samples in SA2 may be used to replace samples in the overlap. Similarly, when sample replacement is applied to the overlap between B and SA2, samples in SA1 may be used to replace samples in the overlap.

[0217] In some example implementations, such as Fig.26 As shown, CTU / SB 2602 and 2604 form a disallowed area. However, in some other implementations, CTU / SB 2602 and / or 2604 may also be part of a local search area (or adjacent allowed search area, SA2). For example, if the on-chip memory is large enough to hold / accommodate the samples in 2602 and / or 2604.

[0218] The present disclosure describes methods, apparatus, and computer-readable media for video encoding / decoding. The present disclosure solves various problems of IntraBC. The methods, apparatus, and computer-readable media described in the present disclosure can enhance the performance of video codecs, optimize the use of on-chip memory in codecs, and facilitate the selection and adjustment of prediction regions of IntraBC.

[0219] Fig. 27 An exemplary method 2700 for processing video data is shown. The method 1900 may include some or all of the following steps: step 2710, receiving a video bitstream, the video bitstream including at least one block of a video frame, the at least one block including a current block; step 2720, determining a first search area in the video frame, wherein the first search area is a first candidate area for locating an intra-block copy (IntraBC) prediction block, wherein the first search area does not overlap with the current block and includes a list of blocks, the IntraBC prediction block is a candidate block for IntraBC prediction of at least a portion of the current block; step 273 0, determine a second search area, wherein the second search area is a second candidate area for locating the IntraBC prediction block, and the second search area includes at least one of the following: (i) a subblock of the current block, and (ii) a neighboring block of the current block; step 2740, identify the IntraBC prediction block referenced by a block vector; step 2750, determine a prediction strategy based on a spatial relationship between the IntraBC prediction block, the first search area and the second search area; and step 2760, decode at least a portion of the current block based on the determined prediction.

[0220] In the embodiments and implementations of the present disclosure, any steps and / or operations may be combined or arranged in any number or order as needed. Two or more of the steps and / or operations may be performed in parallel. The embodiments and implementations in the present disclosure may be used alone or in combination in any order. In addition, each of the method (or embodiment), encoder, and decoder may be implemented by a processing circuit (e.g., one or more processors or one or more integrated circuits). In one example, one or more processors execute a program stored in a non-temporary computer-readable medium. The embodiments in the present disclosure may be applied to luminance blocks or chrominance blocks. The term 'block' may be interpreted as a prediction block, a coding block, or a coding unit, i.e., a CU. The term 'block' here may also be used to refer to a transform block. In the following items, when a block size is mentioned, it may refer to the width or height of the block, or the maximum value of the width and height, or the minimum value of the width and height, or the area size of the block (width * height), or the aspect ratio (width: height, or height: width).

[0221] The above techniques may be implemented as computer software using computer-readable instructions and physically stored in one or more computer-readable media. Fig.28 A computer system (2800) suitable for implementing certain embodiments of the disclosed subject matter is shown.

[0222] Computer software may be encoded using any suitable machine code or computer language that may be subjected to assembly, compilation, linking or similar mechanisms to create code comprising instructions that may be executed directly by one or more computer central processing units (CPUs), graphics processing units (GPUs), etc., or through interpretation, microcode, etc.

[0223] These instructions may be executed on various types of computers or components thereof, including, for example, personal computers, tablet computers, servers, smartphones, gaming devices, IoT devices, and the like.

[0224] Fig.28 The components of the computer system (2800) shown are exemplary in nature and are not intended to suggest any limitation on the scope of use or functionality of computer software implementing embodiments of the present disclosure. Nor should the configuration of components be interpreted as having any dependency or requirement relating to any one component or combination of components shown in the exemplary embodiment of the computer system (2800).

[0225] The computer system (2800) may include certain human-machine interface input devices. Such human-machine interface input devices may respond to input from one or more human-machine interface users through, for example, tactile input (e.g., keystrokes, swipes, data glove motions), audio input (e.g., voice, clapping), visual input (e.g., gestures), olfactory input (not shown). Human-machine interface devices may also be used to capture certain media that are not necessarily directly related to conscious human input, such as audio (e.g., voice, music, ambient sounds), images (e.g., scanned images, photographic images obtained from a still image camera), and videos (e.g., two-dimensional video, three-dimensional video including stereoscopic video).

[0226] The input human-machine interface devices may include one or more (only one of each is shown) of a keyboard (2801), a mouse (2802), a touch pad (2803), a touch screen (2810), data gloves (not shown), a joystick (2805), a microphone (2806), a scanner (2807), and a camera (2808).

[0227] The computer system (2800) may also include certain human-computer interface output devices. Such human-computer interface output devices may stimulate one or more human user senses through, for example, tactile output, sound, light, and smell / taste. Such human-computer interface output devices may include tactile output devices (e.g., tactile feedback of a touch screen (2810), a data glove (not shown), or a joystick (2805), but there may also be tactile feedback devices that are not used as input devices), audio output devices (e.g., speakers (2809), headphones (not shown)), visual output devices (e.g., screens (2810), including CRT screens, LCD screens, plasma screens, OLED screens, each with or without touch screen input capabilities, each with or without tactile feedback capabilities - some of which may be capable of outputting two-dimensional visual output or greater than three-dimensional output through devices such as stereo output; virtual reality glasses (not depicted), holographic displays, and smoke canisters (not depicted)) and printers (not depicted).

[0228] The computer system (2800) may also include human-accessible storage devices and their associated media: for example, optical media including CD / DVD ROM / RW (2820) with CD / DVD etc. media (2821), thumb drives (2822), removable hard drives or solid-state drives (2823), traditional magnetic media such as tapes and floppy disks (not shown), dedicated ROM / ASIC / PLD based devices such as security dongles (not shown), etc.

[0229] Those skilled in the art should also understand that the term "computer-readable media" used in connection with the presently disclosed subject matter does not encompass transmission media, carrier waves, or other transient signals.

[0230] The computer system (2800) may also include an interface (2854) to one or more communication networks (2855). The network may be, for example, a wireless network, a wired network, an optical network. The network may also be a local network, a wide area network, a metropolitan area network, a vehicle and industrial network, a real-time network, a delay-tolerant network, etc. Examples of networks include local area networks such as Ethernet, wireless LANs, cellular networks including GSM, 3G, 4G, 5G, LTE, etc., television wired or wireless wide area digital networks including cable television, satellite television, and terrestrial broadcast television, vehicle and industrial television including CANBus, etc. Some networks typically require an external network interface adapter connected to some common data port or peripheral bus (2849) (e.g., a USB port of the computer system (2800)); as described below, other network interfaces are typically integrated into the kernel of the computer system (2800) by connecting to the system bus (e.g., connecting to an Ethernet interface in a PC computer system or connecting to a cellular network interface in a smartphone computer system). The computer system (2800) can use any of these networks to communicate with other entities. Such communications may be one-way receive only (e.g., broadcast television), one-way send only (e.g., a CANbus connected to certain CANbus devices), or bidirectional, for example, using a LAN or WAN digital network to connect to other computer systems. As described above, certain protocols and protocol stacks may be used on each of those networks and network interfaces.

[0231] The aforementioned human-machine interface device, human-machine interaction storage device and network interface may be connected to the kernel (2840) of the computer system (2800).

[0232] The kernel (2840) may include one or more central processing units (CPUs) (2841), graphics processing units (GPUs) (2842), dedicated programmable processing units in the form of field programmable gate arrays (FPGAs) (2843), hardware accelerators (2844) for certain tasks, graphics adapters (2850), etc. These devices, as well as read-only memory (ROM) (2845), random access memory (2846), internal mass storage (2847) such as internal non-user accessible hard drives, SSDs, etc., may be connected via a system bus (2848). In some computer systems, the system bus (2848) may be accessed in the form of one or more physical plugs to enable expansion by additional CPUs, GPUs, etc. Peripheral devices may be connected directly to the kernel's system bus (2848) or to the kernel's system bus via a peripheral bus (2849). In one example, a screen (2810) may be connected to a graphics adapter (2850). The architecture of the peripheral bus includes PCI, USB, etc.

[0233] The CPU (2841), GPU (2842), FPGA (2843) and accelerator (2844) can execute certain instructions, which can be combined to form the above-mentioned computer code. The computer code can be stored in ROM (2845) or RAM (2846). Transition data can also be stored in RAM (2846), while permanent data can be stored, for example, in internal mass storage (2847). Fast storage and retrieval to any storage device can be performed by using a cache, which can be closely associated with the following: one or more CPUs (2841), GPUs (2842), mass storage (2847), ROM (2845), RAM (2846), etc.

[0234] The computer readable medium may have thereon computer codes for performing various computer-implemented operations. The medium and computer codes may be those specially designed and constructed for the purposes of the present disclosure, or the medium and computer codes may be of a type well known and available to those skilled in the art of computer software.

[0235] As a non-limiting example, a computer system having an architecture (2800), particularly a kernel (2840), can provide functionality due to one or more processors (including CPUs, GPUs, FPGAs, accelerators, etc.) executing software contained in one or more tangible computer-readable media. Such computer-readable media can be media associated with user-accessible mass storage as described above, as well as certain non-temporary memories of the kernel (2840), such as kernel internal mass storage (2847) or ROM (2845). Software implementing various embodiments of the present disclosure can be stored in such devices and executed by the kernel (2840). Depending on specific needs, the computer-readable medium may include one or more storage devices or chips. The software can cause the kernel (2840), particularly the processors therein (including CPUs, GPUs, FPGAs, etc.) to perform specific processes or specific parts of specific processes described herein, including defining data structures stored in RAM (2846) and modifying such data structures according to processes defined by the software. Additionally or alternatively, the computer system may provide functionality due to logic hardwired or otherwise embodied in circuitry (e.g., accelerator (2844)) that may replace software or operate in conjunction with software to perform specific processes or specific portions of specific processes described herein. Where appropriate, references to portions of software may include logic and vice versa. Where appropriate, references to portions of computer-readable media may include circuitry (e.g., integrated circuits (ICs)) storing software for execution, circuitry embodying logic for execution, or both. The present disclosure includes any suitable combination of hardware and software.

[0236] Although the present disclosure has described a number of exemplary embodiments, there are modifications, permutations, and various replacement equivalents that fall within the scope of the present disclosure. Therefore, it should be understood that those skilled in the art will be able to design many systems and methods that, although not explicitly shown or described herein, embody the principles of the present disclosure and therefore fall within the spirit and scope of the present disclosure.

[0237] Appendix A: Abbreviations

[0238] IBC: Intra Block Copy

[0239] IntraBC: Intra Block Copy

[0240] JEM: Joint Exploration Model

[0241] VVC: Next Generation Video Coding

[0242] BMS: Benchmark Set

[0243] MV: Motion Vector

[0244] HEVC: High Efficiency Video Coding

[0245] SEI: Supplemental Enhancement Information

[0246] VUI: Video Availability Information

[0247] GOPs: Group of Pictures

[0248] TUs: Transformation Units

[0249] PUs: Prediction Units

[0250] CTUs: Coding Tree Units

[0251] CTBs: Coding Tree Blocks

[0252] PBs: prediction blocks

[0253] HRD: Hypothetical Reference Decoder

[0254] SNR: Signal to Noise Ratio

[0255] CPU: Central Processing Unit

[0256] GPUs: Graphics Processing Units

[0257] CRT: cathode ray tube

[0258] LCD: Liquid Crystal Display

[0259] OLED: Organic Light Emitting Diode

[0260] CD: compact disc

[0261] DVD: Digital Video Disc

[0262] ROM: Read Only Memory

[0263] RAM: Random Access Memory

[0264] ASIC: Application-Specific Integrated Circuit

[0265] PLD: Programmable Logic Device

[0266] LAN: Local Area Network

[0267] GSM: Global System for Mobile Communications

[0268] LTE: Long Term Evolution

[0269] CANBus: Controller Area Network Bus

[0270] USB: Universal Serial Bus

[0271] PCI: Peripheral Component Interconnect

[0272] FPGA: Field Programmable Gate Array

[0273] SSD: Solid State Drive

[0274] IC: Integrated Circuit

[0275] HDR: High Dynamic Range

[0276] SDR: Standard Dynamic Range

[0277] JVET: Joint Video Exploration Team

[0278] MPM: Most Probable Mode

[0279] WAIP: Wide Angle Intra Prediction

[0280] CU: Coding Unit

[0281] PU: prediction unit

[0282] TU: Transformation Unit

[0283] CTU: Coding Tree Unit

[0284] PDPC: Position Dependent Prediction Combination

[0285] ISP: Intra-frame sub-partitioning

[0286] SPS: Sequence Parameter Set

[0287] PPS: Picture Parameter Set

[0288] APS: Adaptive Parameter Set

[0289] VPS: Video Parameter Set

[0290] DPS: Decoding Parameter Set

[0291] ALF: Adaptive Loop Filter

[0292] SAO: Sample Adaptive Offset

[0293] CC-ALF: Cross-Component Adaptive Loop Filter

[0294] CDEF: Constrained Directional Enhancement Filter

[0295] CCSO: Cross-Component Sample Offset

[0296] LSO: Local Sample Offset

[0297] LR: Loop Restoration Filter

[0298] AV1: Alliance for Open Media (AOMedia) Video 1

[0299] AV2: AOMedia Video 2

[0300] RPS: Reference Picture Set

[0301] DPB: Decoded Picture Buffer

[0302] MMVD: Merge mode with motion vector difference

[0303] IntraBC or IBC: Intra-block Copy

[0304] BV: Block Vector

[0305] BVD: Block Vector Difference

[0306] RSM: Reference Sample Memory

Claims

1. A method for processing video data, characterized in that The method comprises: receiving a video bitstream, the video bitstream comprising at least one block of a video frame, the at least one block comprising a current block; Determining a first search area in the video frame, wherein the first search area is a non-local search area for intra block copy (IntraBC) prediction block search and selection, wherein the first search area does not overlap with the current block and includes a list of blocks, the IntraBC prediction block being a candidate block for IntraBC prediction of at least a portion of the current block; Determine a second search area, wherein the second search area is a local search area for searching and selecting the IntraBC prediction block, and the second search area includes at least one of: (i) a sub-block of the current block, and (ii) a reconstructed neighboring block of the current block; the first search area and the second search area do not overlap; samples in the first search area are stored in an off-chip memory, and samples in the second search area are stored in an on-chip memory; identifying the IntraBC prediction block referenced by the block vector; in response to the IntraBC prediction block being partially located in the first search area and partially located in the second search area, determining an area where the IntraBC prediction block overlaps with the first search area as a first overlapping area, and determining an area where the IntraBC prediction block overlaps with the second search area as a second overlapping area; Based on the size of the first overlapping area and the size of the second overlapping area, selecting one of the first overlapping area and the second overlapping area as a target overlapping area; and replacing samples in the target overlapping area with boundary samples adjacent to the target overlapping area in the IntraBC prediction block to obtain an updated IntraBC prediction block; and At least a portion of the current block is decoded based on the updated IntraBC prediction block.

2. The method according to claim 1, characterized in that: The method further comprises: In response to the IntraBC prediction block being a subset of the first search area or a subset of the second search area, allowing IntraBC prediction of at least a portion of the current block using the IntraBC prediction block, the first search area and the second search area do not overlap.

3. The method according to claim 2, characterized in that The current block includes a super block.

4. The method according to claim 1, characterized in that: The neighboring block of the current block is in the same row as the current block and is located on the left side of the current block, and the neighboring block of the current block has the same size as the current block.

5. The method according to any one of claims 1 to 4, characterized in that: The coordinate position of the upper left corner pixel of the current block is (x0, y0); The coordinate position of the upper left corner pixel of each block in the block list is (x, y); y is less than y0; and x is less than [x0+2(y0-y)-D], Where x0, y0, x and y are non-negative numbers, and D is the number of immediately reconstructed blocks limited for IntraBC mode.

6. The method according to claim 5, characterized in that D is equal to 2.

7. The method according to claim 1, characterized in that The selecting one of the first overlapping area and the second overlapping area as the target overlapping area comprises: In response to the size of the second overlapping area being greater than or equal to the size of the first overlapping area, selecting the first overlapping area as the target overlapping area; and In response to the size of the first overlapping area being larger than the size of the second overlapping area, the second overlapping area is selected as the target overlapping area.

8. The method according to claim 1, characterized in that: The selecting one of the first overlapping area and the second overlapping area as the target overlapping area comprises: In response to the size of the second overlapping area being greater than or equal to a first threshold, selecting the first overlapping area as the target overlapping area, wherein the first threshold is a product of the size of the first overlapping area and a predefined first bias factor; and In response to the size of the first overlapping area being greater than or equal to a second threshold, the second overlapping area is selected as the target overlapping area, wherein the second threshold is a product of the size of the second overlapping area and a predefined second bias factor.

9. The method according to claim 8, characterized in that The sizes of the first overlapping region and the second overlapping region are represented by the number of samples in each respective region.

10. The method according to claim 9, wherein: The number of samples includes one of the following: the number of luminance samples; or The number of chroma samples.

11. The method according to any one of claims 8 to 10, characterized in that: The replacing samples in the target overlapping area comprises: In response to the target overlapping region being the first overlapping region, replacing samples in the target overlapping region with samples from the second overlapping region; and In response to the target overlap region being the second overlap region, replacing samples in the target overlap region with samples from the first overlap region.

12. The method according to any one of claims 1 to 4, characterized in that: Samples in the second search area are stored in an on-chip memory of a video codec processing the video data.

13. A device for processing video data, characterized in that A device comprising a memory for storing computer instructions and a processor in communication with the memory, wherein when the processor executes the computer instructions, the processor is configured to cause the device to: receiving a video bitstream, the video bitstream comprising at least one block of a video frame, the at least one block comprising a current block; Determining a first search area in the video frame, wherein the first search area is a non-local search area for intra block copy (IntraBC) prediction block search and selection, wherein the first search area does not overlap with the current block and includes a list of blocks, the IntraBC prediction block being a candidate block for IntraBC prediction of at least a portion of the current block; Determine a second search area, wherein the second search area is a local search area for searching and selecting the IntraBC prediction block, and the second search area includes at least one of: (i) a sub-block of the current block, and (ii) a reconstructed neighboring block of the current block; the first search area and the second search area do not overlap; samples in the first search area are stored in an off-chip memory, and samples in the second search area are stored in an on-chip memory; identifying the IntraBC prediction block referenced by the block vector; in response to the IntraBC prediction block being partially located in the first search area and partially located in the second search area, determining an area where the IntraBC prediction block overlaps with the first search area as a first overlapping area, and determining an area where the IntraBC prediction block overlaps with the second search area as a second overlapping area; Based on the size of the first overlapping area and the size of the second overlapping area, selecting one of the first overlapping area and the second overlapping area as a target overlapping area; and replacing samples in the target overlapping area with boundary samples adjacent to the target overlapping area in the IntraBC prediction block to obtain an updated IntraBC prediction block; and At least a portion of the current block is decoded based on the updated IntraBC prediction block.

14. The device according to claim 13, characterized in that When the processor is configured to cause the device to select the target overlapping area, the processor is configured to cause the device to: In response to the size of the second overlapping area being greater than or equal to the size of the first overlapping area, selecting the first overlapping area as the target overlapping area; as well as In response to the size of the first overlapping area being larger than the size of the second overlapping area, the second overlapping area is selected as the target overlapping area.

15. The device according to claim 13, characterized in that When the processor is configured to cause the device to select the target overlapping area, the processor is configured to cause the device to: In response to the size of the second overlapping area being greater than or equal to a first threshold, selecting the first overlapping area as the target overlapping area, wherein the first threshold is a product of the size of the first overlapping area and a predefined first bias factor; and In response to the size of the first overlapping area being greater than or equal to a second threshold, the second overlapping area is selected as the target overlapping area, wherein the second threshold is a product of the size of the second overlapping area and a predefined second bias factor.

16. A non-transitory storage medium, characterized in that: For storing computer readable instructions, which, when executed by a processor, cause the processor to: receiving a video bitstream, the video bitstream comprising at least one block of a video frame, the at least one block comprising a current block; Determining a first search area in the video frame, wherein the first search area is a non-local search area for intra block copy (IntraBC) prediction block search and selection, wherein the first search area does not overlap with the current block and includes a list of blocks, the IntraBC prediction block being a candidate block for IntraBC prediction of at least a portion of the current block; Determine a second search area, wherein the second search area is a local search area for searching and selecting the IntraBC prediction block, and the second search area includes at least one of: (i) a sub-block of the current block, and (ii) a reconstructed neighboring block of the current block; the first search area and the second search area do not overlap; samples in the first search area are stored in an off-chip memory, and samples in the second search area are stored in an on-chip memory; identifying the IntraBC prediction block referenced by the block vector; in response to the IntraBC prediction block being partially located in the first search area and partially located in the second search area, determining an area where the IntraBC prediction block overlaps with the first search area as a first overlapping area, and determining an area where the IntraBC prediction block overlaps with the second search area as a second overlapping area; Based on the size of the first overlapping area and the size of the second overlapping area, selecting one of the first overlapping area and the second overlapping area as a target overlapping area; and replacing samples in the target overlapping area with boundary samples adjacent to the target overlapping area in the IntraBC prediction block to obtain an updated IntraBC prediction block; and At least a portion of the current block is decoded based on the updated IntraBC prediction block.

17. A method for processing a video code stream, characterized in that: The video code stream is decoded based on the method for processing video data according to any one of claims 1 to 12.

Images