Method, device, electronic device and storage medium for decoding current video block

Abstract

Embodiments of the present application disclose a method, apparatus, electronic device, and storage medium for decoding a current video block of a video stream. The method includes receiving an encoded video stream; obtaining a first motion vector difference (MVD) and a dynamic reference list (DRL) index for the current video block from the encoded video stream; deriving a second MVD for the current video block based on the first MVD; generating, by a device, a motion vector (MV) pair based on the first MVD, the derived second MVD, and a motion vector predictor (MVP) indicated by the DRL index; and decoding, by the device, the current video block based on the MV pair.

Description

[0001] Incorporation by reference

[0002] This application is based on and claims priority to U.S. Provisional Patent Application No. 63 / 261,252, filed on September 15, 2021, the entire contents of which are incorporated herein by reference. This application is based on and claims priority to U.S. Non-Provisional Patent Application No. 17 / 945,935, filed on September 15, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure generally relates to video encoding and decoding, and more particularly to a method, apparatus, electronic device, and storage medium for decoding a current video block. Background Art

[0004] The background description provided herein is intended to generally present the context of the present application. To the extent described in this background section, the work of the presently named inventors, as well as aspects of the description that may not have qualified as prior art at the time the present application was filed, are neither explicitly nor implicitly admitted to being prior art to the present application.

[0005] Video encoding and decoding can use inter-picture prediction with motion compensation. Uncompressed digital video may include a series of pictures, each picture having a certain spatial dimension, for example, 1920×1080 luma samples and associated full chroma samples or subsampled chroma samples. The series of pictures may have a fixed or variable picture rate (alternatively referred to as a frame rate), for example, 60 pictures per second or 60 frames per second. Uncompressed video has specific bit rate requirements for streaming or data processing. For example, a video with a pixel resolution of 1920×1080, a frame rate of 60 frames per second, and 4:2:0 chroma downsampling with 8 bits per pixel per color channel requires a bandwidth of nearly 1.5 Gbit / s. One hour of such video requires more than 600 GB of storage space.

[0006] One goal of video encoding and decoding can be to reduce redundancy in an uncompressed input video signal through compression. Compression can help reduce the bandwidth and / or storage space requirements mentioned above, in some cases by two or more orders of magnitude. Both lossless and lossy compression, as well as combinations thereof, can be used for video encoding and decoding. Lossless compression refers to techniques that can reconstruct an exact replica of the original signal from the compressed original signal through a decoding process. Lossy compression refers to an encoding / decoding process in which the original video signal is not completely preserved during the encoding process and not completely restored during the decoding process. When using lossy compression, the reconstructed signal may not be completely identical to the original signal, but the distortion between the original and reconstructed signals is small enough that the reconstructed signal can be used for the intended application, albeit with some information loss. For video, lossy compression is widely used in many applications. The amount of distortion that can be tolerated by lossy compression depends on the application. For example, consumer users of certain 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 generally allows the use of encoding algorithms that produce higher losses and higher compression ratios.

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

[0008] Video coding techniques may include intra-frame coding techniques. In intra-frame coding techniques, sample values ​​are represented without reference to samples or other data in previously reconstructed reference pictures. In some video coding techniques, a picture is spatially divided into blocks of samples. When all sample blocks are encoded using intra-frame mode, the picture can be called an intra-frame picture. Intra-frame pictures and their derivatives, such as independent decoder refresh pictures, can be used to reset the state of the decoder and can therefore be used as the first picture in an encoded video stream and video session, or as a still picture. The samples of the intra-frame predicted block can then be transformed into the frequency domain, and the transform coefficients generated in this way can be quantized before entropy coding. Intra-frame prediction refers to 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 required to represent the entropy coded block for a given quantization step size.

[0009] Traditional intra-frame coding techniques, such as the known MPEG-2 coding techniques, do not use intra-frame prediction. However, some newer video compression techniques include techniques that attempt to encode / decode blocks based on, for example, neighboring sample data and / or metadata obtained during the encoding and / or decoding of data blocks that are spatially adjacent to and preceding in decoding order the data block being intra-coded or decoded. Such techniques are therefore 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 not reference data from other reference pictures.

[0010] Intra-frame prediction can take many different forms. When more than one such technique is available for a given video coding technique, the technique in use is 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, some modes have sub-modes and / or are associated with various parameters, and the mode / sub-mode information and intra-frame coding parameters for a video block may be encoded separately or may be collectively contained in a mode codeword. The codeword used for a given mode / sub-mode and / or parameter combination will affect the coding efficiency gain through intra-frame prediction, as will the entropy coding technique used to translate the codeword into the bitstream.

[0011] The H.264 standard introduced a certain mode of intra-frame prediction, which was improved by the H.265 standard and further improved in newer coding technologies such as the Joint Exploration Model (JEM), Versatile Video Coding (VVC), and Benchmark Sets (BMS). Typically, for intra-frame prediction, a predictor block can be formed using already available adjacent sample values. For example, the available values ​​of adjacent samples of a specific set along a specific direction and / or row can be copied to the prediction block. The reference to the direction used can be encoded into the bitstream, or it can be predicted itself.

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

[0013] Still refer to Figure 1A As shown, Figure 1A Depicted in the upper left corner of FIG. 1 is a square block (104) having 4×4 samples (indicated by a bold dashed line). The square block (104) includes 16 samples, each labeled with an "S," 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 (counting from top to bottom) and the first sample in the X dimension (counting from left to right). Similarly, sample S44 is the fourth sample in both the X and Y dimensions in the block (104). Because the size of the block is 4×4 samples, S44 is in its lower right corner. Figure 1A Example reference samples are further shown, which follow a similar numbering scheme. Reference samples are labeled with R, their Y position (e.g., row index), and X position (e.g., column index) relative to the block (104). In the H.264 and H.265 standards, prediction samples immediately adjacent to the block being reconstructed are used.

[0014] The intra picture prediction for block 104 may begin by copying the reference sample values ​​of adjacent samples according to a prediction direction indicated by a signal. For example, assuming that the coded video stream includes signaling indicating the prediction direction of arrow (102) for block 104, the prediction of the samples in the block is performed based on one or more reference samples in the upper right corner at a 45-degree angle to the horizontal. In this case, samples S41, S32, S23, and S14 are predicted based on the same reference sample R05. 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 one reference sample; in particular when the direction is not divisible by 45 degrees.

[0016] As video coding technology continues to develop, the number of possible directions is also increasing. In the H.264 standard (2003), for example, 9 different directions can be used for intra-frame prediction. In the H.265 standard (2013), this has increased to 33 directions. At the time of the invention of this application, JEM / VVC / BMS can support up to 65 directions. Some experimental studies have been conducted to help identify the most suitable intra-frame prediction directions, and some entropy coding techniques encode these most suitable directions with a small number of bits, accepting a certain bit cost for the directions. In addition, sometimes these directions themselves can be predicted based on the adjacent directions used by adjacent decoded blocks for intra-frame prediction.

[0017] Figure 1BA diagram (180) depicting 65 intra prediction directions according to JEM is shown to illustrate that the number of prediction directions increases over time in various coding techniques.

[0018] The mapping of the bits representing the intra prediction direction to the prediction direction in the coded video stream varies across different video coding techniques; for example, it can range from a simple, direct mapping of the intra prediction mode's prediction direction to a codeword to complex adaptive schemes involving most likely modes and similar techniques. However, in all of these cases, some directions used for intra prediction are statistically less likely to occur in the video content than others. Since the goal of video compression is to reduce redundancy, these less likely directions are represented using more bits than more likely directions in better performing video coding techniques.

[0019] Intra-frame prediction or inter-frame prediction can be based on motion compensation. In motion compensation, a block of sample data from a previously reconstructed picture or part thereof (reference picture) can be used to predict a newly reconstructed picture or picture part (e.g., block) after being spatially shifted in the direction indicated by a motion vector (hereinafter referred to as 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 in use (i.e., the temporal dimension).

[0020] In some video compression techniques, the current MV applicable to a region of sample data can be predicted based on other MVs, for example, MVs associated with another region of sample data that is spatially adjacent to the region being reconstructed and precedes the MV in decoding order. This significantly reduces the total amount of data required to encode the MV by eliminating redundancy in the associated MVs, thereby improving compression efficiency. For example, MV prediction works effectively because when encoding an input video signal from a camera (referred to as native video), there is a statistical probability that regions larger than the one for which a single MV applies move in similar directions within the video sequence. Therefore, similar motion vectors derived from MVs in neighboring regions can be used for prediction in some cases. This results in the actual MV in a given region being similar or identical to the MV predicted from surrounding MVs. Such MVs, after entropy coding, can be represented using fewer bits than would be used if the MV were encoded directly rather than predicted from neighboring 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 corrupted, for example due to rounding errors when computing the predictor from several surrounding MVs.

[0021] H.265 / HEVC (ITU-T Recommendation H.265, "High Efficiency Video Coding," December 2016) describes various MV prediction mechanisms. Among the various MV prediction mechanisms specified in H.265, the technique called "spatial merging" is described below.

[0022] Specifically, refer to Figure 2 As shown, the current block (201) includes samples that the encoder found during motion search to be predictable from a previous block of the same size as the current block (which has been spatially shifted). The MV is not encoded directly, but can be derived from metadata associated with one or more reference pictures (e.g., the most recent (in decoding order) reference picture) using the MV associated with any of the five surrounding samples (denoted as A0, A1, B0, B1, B2 (202 to 206 respectively)). In H.265, MV prediction can use predictors from the same reference picture as its neighboring blocks. Summary of the Invention

[0023] This disclosure describes various embodiments of methods, apparatus, and computer-readable storage media for video encoding and / or decoding.

[0024] According to one aspect, an embodiment of the present disclosure provides a method for decoding a current video block of a video stream. The method includes receiving an encoded video stream by a device. The device includes a memory storing instructions and a processor communicating with the memory. The method also includes obtaining, by the device, a first motion vector difference (MVD) and a dynamic reference list (DRL) index for the current video block from the encoded video stream; deriving, by the device, a second MVD for the current video block based on the first MVD; generating, by the device, a motion vector (MV) pair based on the first MVD, the derived second MVD, and a motion vector predictor (MVP) indicated by the DRL index; and decoding, by the device, the current video block based on the MV pair.

[0025] According to another aspect, an embodiment of the present invention provides an apparatus for decoding a current video block of a video stream. The apparatus includes a memory storing instructions; and a processor in communication with the memory. When the processor executes the instructions, the processor is configured to cause the apparatus to perform the aforementioned method for video decoding and / or encoding.

[0026] In another aspect, an embodiment of the present disclosure provides a non-transitory computer-readable medium storing instructions, which, when executed by a computer for video decoding and / or encoding, causes the computer to perform the above-described method for video decoding and / or encoding.

[0027] The above and other aspects and their implementations are described in more detail in the drawings, description, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Other features, properties, and various advantages of the disclosed subject matter will become more apparent from the following detailed description and accompanying drawings, in which:

[0029] Figure 1A A schematic diagram illustrating an exemplary subset of intra prediction direction modes;

[0030] Figure 1B A diagram showing exemplary intra prediction directions;

[0031] Figure 2 A schematic diagram showing a current block and its surrounding spatial merging candidates for motion vector prediction in an example is shown;

[0032] Figure 3 a schematic diagram showing a simplified block diagram of a communication system (300) according to an example embodiment;

[0033] Figure 4 A schematic diagram illustrating a simplified block diagram of a communication system (400) according to an example embodiment;

[0034] Figure 5 a schematic diagram showing a simplified block diagram of a video decoder according to an example embodiment;

[0035] Figure 6 A schematic diagram illustrating a simplified block diagram of a video encoder according to an example embodiment;

[0036] Figure 7 shows a block diagram of a video encoder according to another example embodiment;

[0037] Figure 8 shows a block diagram of a video decoder according to another example embodiment;

[0038] Figure 9 A scheme for encoding block partitioning according to an exemplary embodiment of the present disclosure is shown;

[0039] Figure 10 Another scheme of coding block partitioning according to an exemplary embodiment of the present disclosure is shown;

[0040] Figure 11 Another scheme of coding block partitioning according to an exemplary embodiment of the present disclosure is shown;

[0041] Figure 12 An example of partitioning a basic block into coding blocks according to an example partitioning scheme is shown;

[0042] Figure 13An example ternary partitioning scheme is shown;

[0043] Figure 14 An example quadtree binary tree coding block partitioning scheme is shown;

[0044] Figure 15 A scheme for partitioning a coding block into multiple transform blocks and a coding order of the transform blocks according to an exemplary embodiment of the present disclosure is shown;

[0045] Figure 16 Another scheme for partitioning a coding block into multiple transform blocks and the encoding order of the transform blocks according to an example embodiment of the present disclosure is shown;

[0046] Figure 17 Another scheme for partitioning a coding block into multiple transform blocks according to an example embodiment of the present disclosure is shown;

[0047] Figure 18 A flowchart illustrating a method according to an example embodiment of the present disclosure is shown;

[0048] Figure 19 A schematic diagram of a computer system according to an example embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0049] Throughout the specification and claims, terms may have meanings that are implied or connoted by the context in addition to their explicitly stated meanings. The phrases "in one embodiment" or "in some embodiments" used in this application do not necessarily refer to the same embodiment, and the phrases "in another embodiment" or "in other embodiments" used in this application do not necessarily refer to different embodiments. Similarly, the phrases "in one embodiment" or "in some embodiments" used in this application do not necessarily refer to the same embodiment, and the phrases "in another embodiment" or "in other embodiments" used in this application do not necessarily refer to different embodiments. For example, it is intended that the claimed subject matter includes all or part of the combination of the example embodiments / embodiments.

[0050] In general, terms can be understood at least in part based on their usage in the context. For example, terms such as "and", "or" or "and / or" used in this application can include various meanings, which may depend at least in part on the context in which the terms are used. Typically, "or" if used in an associative list, such as A, B or C, is intended to mean A, B and C (here in an inclusive sense) as well as A, B or C (here in an exclusive sense). In addition, the terms "one or more" or "at least one" used in this application, depending at least in part on the context, can be used to describe any feature, structure or characteristic in the singular sense, or can be used to describe a combination of features, structures or characteristics in the plural sense. Similarly, terms such as "a" or "an" or "the" can be understood to convey singular usage or to convey plural usage, depending 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 represent a set of exclusive factors, but rather to allow for the presence of other factors that are not necessarily explicitly described, again, depending at least in part on the context. Figure 3 The figure shows a simplified block diagram of a communication system (300) according to an embodiment disclosed in the present application. 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 3In an example, a first pair of terminal devices (310) and (320) can perform unidirectional data transmission. For example, the terminal device (310) can encode video data (e.g., a video picture stream collected by the terminal device (310)) for transmission to another terminal device (320) via a network (350). The encoded video data can be transmitted in the form of one or more encoded video code streams. 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. 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, and the bidirectional transmission can be implemented, for example, during a video conference. For bidirectional data transmission, in one example, each of the terminal device (330) and the terminal device (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 the terminal device (340) through the network (350). Each of the terminal device (330) and the terminal device (340) can also receive the encoded video data transmitted by the other terminal device (330) and the terminal device (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.

[0051] exist Figure 3 In the example of , terminal device (310), terminal device (320), terminal device (330) and terminal device (340) may be implemented as a server, a personal computer and a smart phone, but the underlying principles disclosed in the present application may not be limited thereto. The embodiments disclosed in the present application may be implemented in a laptop computer, a laptop computer, a tablet computer, a media player, a wearable computer, a dedicated video conferencing device, and the like. Network (350) represents any number or type of network that transmits encoded video data between terminal device (310), terminal device (320), terminal device (330) and terminal device (340), including, for example, wired (wired) and / or wireless communication networks. The communication network (350) may exchange data in circuit switching, packet switching channels and / or other types of channels. Representative networks include telecommunications networks, local area networks, wide area networks and / or the Internet. For the purposes of this discussion, unless otherwise explicitly explained below, the architecture and topology of the network (350) may be irrelevant to the operations disclosed in the present application.

[0052] As an example of the application of the subject matter disclosed in this application, Figure 4The video encoder and video decoder are placed in a video streaming environment. The subject matter disclosed in this application is equally applicable to other video applications, including, for example, video conferencing, digital TV, broadcasting, gaming, virtual reality, storing compressed video on digital media including CDs, DVDs, memory sticks, etc.

[0053] The video streaming system may include a video capture 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 one example, the video picture stream (402) includes samples captured by the digital camera of the video source 401. The video picture stream (402) is depicted as a thick line to emphasize that it has a higher data volume than the encoded video data (404) (or encoded video bitstream). The video picture stream (402) may be processed by an electronic device (420) including 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 embody various aspects of the disclosed subject matter as described in more detail below. The encoded video data (404) (or encoded video code stream (404)) is depicted as a thin line to emphasize that it has a lower data volume compared to the uncompressed video picture stream (402), which can be stored on the streaming server (405) for future use or directly stored to 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 streaming server (405) can access the streaming server (405) to retrieve a copy (407) and a copy (409) of the encoded video data (404). The client subsystem (406) can 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 uncompressed output video picture stream (411) that 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 this disclosure. In some streaming systems, the encoded video data (404), the video data (407), and the video data (409) (e.g., a video bitstream) can be encoded according to certain video encoding / compression standards. Examples of such standards include ITU-T Recommendation H.265. In one example, a video coding standard under development is informally referred to as Versatile Video Coding (VVC), and the subject matter disclosed herein may be used in the context of the VVC standard and other video coding standards.

[0054] 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).

[0055] Figure 5 The following is a block diagram of a video decoder (510) according to any embodiment disclosed in the present application. The video decoder (510) may be provided 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 (410) is shown in the example.

[0056] A receiver (531) may receive one or more encoded video sequences to be decoded by a 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 decoding 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 transmitting the encoded video data. The receiver (531) may receive the encoded video data as well as 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 external to the video decoder (510) and separate from the video decoder (510) (not depicted). In yet other applications, a buffer memory (not depicted) may be provided external to the video decoder (510), for example, to prevent network jitter, and another additional buffer memory (515) may be provided internal to the video decoder (510), for example, to handle playback timing. When the receiver (531) receives data from a store / forward device with sufficient bandwidth and controllability, or from an isochronous network, the buffer memory (515) may not be required, 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 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 at least partially implemented in an operating system or similar component (not depicted) external to the video decoder (510).

[0057] The video decoder (510) may include a parser (520) to reconstruct symbols (521) from the encoded video sequence. The types of symbols include information used to manage the operation of the video decoder (510) and potentially information used to control a display device such as a display (512) (e.g., a display screen), which may or may not be part of the electronic device (530) but may be coupled to the electronic device (530), such as Figure 5As shown. The control information for the display device may be a parameter set fragment (not depicted) of a Supplemental Enhancement Information (SEI) message or a Video Usability Information (VUI) message. The parser (520) may parse / entropy decode the coded video sequence it receives. Entropy coding of the coded 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 for at least one subgroup of the subgroups of pixels in the video decoder from the coded 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), quantizer parameter values, motion vectors, and so on.

[0058] The parser (520) may perform entropy decoding / parsing operations on the video sequence received from the buffer memory (515), thereby creating symbols (521).

[0059] Depending on the type of coded video picture or coded video picture portion (e.g., inter-frame and intra-frame pictures, inter-frame blocks and intra-frame blocks) and other factors, the reconstruction of the symbol (521) may involve multiple different processing or functional units. Which units are involved and how they are involved can be controlled by subgroup control information parsed from the coded video sequence by the parser (520). For the sake of brevity, the flow of such subgroup control information between the parser (520) and the multiple processing or functional units described below is not described.

[0060] In addition to the functional blocks already mentioned, the video decoder (510) can be conceptually subdivided into several functional units as described below. In practical embodiments operating under commercial constraints, many of these functional units interact closely with each other and may be at least partially integrated with each other. However, for the purpose of clearly describing the various functions of the disclosed subject matter, this disclosure adopts a conceptual subdivision of functional units below.

[0061] The first unit may include a scaler / inverse transform unit (551). The scaler / inverse transform unit (551) may receive quantized transform coefficients as symbols (521) and control information from the parser (520), including an indication of which type of inverse transform method to use, block size, quantization factors / parameters, quantization scaling matrix, etc. The scaler / inverse transform unit (551) may output a block including sample values, which may be input to the aggregator (555).

[0062] In some cases, the output samples of the scaler / inverse transform unit (551) may belong to intra-coded blocks; that is, blocks that do not use predictive information from a previously reconstructed picture, but may use predictive information from a previously reconstructed portion of the current picture. Such predictive information may be provided by the 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 information from surrounding blocks that have already been reconstructed and stored in the current picture buffer (558). For example, the current picture buffer (558) buffers partially reconstructed current pictures and / or fully reconstructed current pictures. In some embodiments, the aggregator (555) may add the prediction information generated by the intra-picture prediction unit (552) to the output sample information provided by the scaler / inverse transform unit (551) on a per-sample basis.

[0063] In other cases, the output samples of the scaler / inverse transform unit (551) may belong to an inter-frame 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 inter-frame 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) by an aggregator (555) (the output of the unit 551 may be referred to as residual samples or residual signal), thereby generating output sample information. The retrieval of the prediction samples by the motion compensated prediction unit (553) from the address in the reference picture memory (557) may be controlled by a motion vector, and the motion vector is provided to the motion compensated prediction unit (553) in the form of the symbols (521), for example, including an X, Y component (displacement) and a reference picture component (time). Motion compensation may also include interpolation of sample values ​​retrieved from a reference picture memory (557) when using sub-sample accurate motion vectors, may also be associated with a motion vector prediction mechanism, and so on.

[0064] The output samples of the aggregator (555) can be used by various loop filtering techniques in a loop filter unit (556). The video compression techniques can include in-loop filter techniques that are controlled by parameters included in the coded video sequence (also called the coded video bitstream) and available to the loop filter unit (556) as symbols (521) from the parser (520), but can 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 previously reconstructed and loop filtered sample values. Several types of loop filters can be included as part of the loop filter unit 556 in various orders, as described in detail below.

[0065] 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.

[0066] Once fully reconstructed, certain coded pictures can 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) can become part of the reference picture memory (557) and a new current picture buffer can be reallocated before starting to reconstruct a subsequent coded picture.

[0067] The video decoder (510) may perform decoding operations according to a predetermined video compression technique employed in a standard such as ITU-T Recommendation H.265. 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 a profile documented 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. To conform to the standard, it is also required that the complexity of the coded video sequence be within a range defined by the hierarchy of the video compression technique or standard. In some cases, the hierarchy limits the maximum picture size, maximum frame rate, maximum reconstruction sampling rate (measured in, for example, megasamples per second), maximum reference picture size, etc. In some cases, the limits set by the hierarchy may be further defined by the Hypothetical Reference Decoder (HRD) specification and metadata about the HRD buffer management signaled in the coded video sequence.

[0068] In some example embodiments, a receiver (531) may receive additional (redundant) data along with the encoded video. The additional data may be 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, and the like.

[0069] Figure 6 is a block diagram of a video encoder (603) according to an example embodiment disclosed herein. The video encoder (603) may be provided in an electronic device (620). The electronic device (620) may further include a transmitter (640) (e.g., a transmission circuit). The video encoder (603) may be used to replace Figure 4 The video encoder (403) in the example.

[0070] The video encoder (603) can be used to generate a video from a video source (601) (not Figure 6 In another embodiment, the video source (601) may be implemented as part of the electronic device (620) to receive video samples. The video source may capture video images to be encoded by the video encoder (603). In another embodiment, the video source (601) may be implemented as part of the electronic device (620).

[0071] The video source (601) may provide a source video sequence in the form of a stream of digital video samples to be encoded by the video encoder (603), wherein the stream of digital video samples may have any suitable bit depth (e.g., 8-bit, 10-bit, 12-bit, ...), any color space (e.g., BT.601 Y CrCB, RGB, XYZ, ...), and any suitable sampling structure (e.g., Y CrCb 4:2:0, YCrCb 4:4:4). In a media serving system, the video source (601) may be a storage device 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 individual pictures or images that are given motion when viewed sequentially. The pictures themselves may be constructed as a spatial array of pixels, where each pixel may include one or more samples depending on the sampling structure, color space, etc. used. The relationship between pixels and samples can be readily understood by one of ordinary skill in the art. The following description focuses on samples.

[0072] According to an embodiment, 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) controls other functional units as described below and is functionally coupled to these units. For the sake of simplicity, the coupling is not shown 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, etc.), picture size, group of pictures (GOP) layout, maximum motion vector search range, etc. The controller (650) can be used to have other suitable functions that are related to the video encoder (603) optimized for a certain system design.

[0073] According to some example embodiments, the video encoder (603) may operate in a coding loop. As a simplified description, in one example, the coding loop may include a source encoder (630) (e.g., responsible for creating symbols, e.g., a symbol stream, based on an input picture to be coded and a reference picture) and a (local) decoder (633) embedded in the video encoder (603). Even though the embedded decoder 633 processes the non-entropy-coded coded video stream of the source encoder 630, the decoder (633) reconstructs the symbols to create sample data in a manner similar to that of the (remote) decoder (because any compression between the symbols and the coded video stream in entropy coding can be lossless in the video compression technology considered in the subject matter disclosed in this application). 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 regardless of the decoder location (local or remote), the contents of the reference picture memory (634) also correspond bit-accurately between the local encoder and the remote encoder. In other words, the reference picture samples "seen" by the prediction portion of the encoder are exactly the same sample values ​​that the decoder will "see" when using prediction during decoding. This fundamental principle of reference picture synchronization (and the drift that occurs when synchronization cannot be maintained, for example due to channel errors) is used to improve encoding quality.

[0074] The operation of the "local" decoder (633) can be combined with the operation of Figure 5 The "remote" decoder described in detail for the video decoder (510) is identical. However, additional brief reference is made to Figure 5, when symbols are available and the entropy encoder (645) and parser (520) are able to losslessly encode / decode the symbols into the coded 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.

[0075] At this point, it can be observed that any decoder technology other than parsing / entropy decoding, which may only exist in a decoder, must also exist in a corresponding encoder in essentially the same functional form. For this reason, this application sometimes focuses on decoder operations, which are similar to the decoding portion of an encoder. 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.

[0076] During operation, in some example embodiments, the source encoder (630) may perform motion-compensated predictive coding to predictively encode an input picture with reference to one or more previously encoded pictures in a video sequence designated as "reference pictures." In this manner, the encoding engine (632) encodes the differences (or residuals) in the color channels 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 "residual" may be used interchangeably.

[0077] The local video decoder (633) may decode the coded video data of a picture that may be designated as a reference picture based on the symbols created by the source encoder (630). The operation of the encoding engine (632) may be a lossy process. When the coded video data is available at the video decoder ( Figure 6 When decoded at a local (not shown) location, 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 the video decoder may perform on the reference picture and may cause the reconstructed reference picture to be stored in the reference picture cache (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 that will be obtained by the remote video decoder.

[0078] 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 suitable prediction references for the new picture. The predictor (635) may operate on a pixel-by-pixel-block basis based on sample blocks to find a suitable prediction reference. In some cases, based on the search results obtained by the predictor (635), it may be determined that the input picture may have prediction references taken from multiple reference pictures stored in the reference picture memory (634).

[0079] The controller (650) can manage encoding operations of the source encoder (630), including, for example, setting parameters and subgroup parameters for encoding video data.

[0080] The outputs of all the above functional units may be entropy coded in an entropy encoder (645). The entropy encoder (645) losslessly compresses the symbols generated by the various functional units using techniques such as Huffman coding, variable length coding, arithmetic coding, etc., thereby converting the symbols into a coded video sequence.

[0081] The transmitter (640) can buffer the encoded video sequence created by the entropy encoder (645) in preparation for transmission over a communication channel (660), which can be a hardware / software link to a storage device where the encoded video data will be stored. The transmitter (640) can combine the encoded video data from the video encoder (603) with other data to be transmitted, such as encoded audio data and / or an auxiliary data stream (source not shown).

[0082] The controller (650) can manage the operation of the video encoder (603). During encoding, the controller (650) can assign a coded picture type to each coded picture, which may affect the coding techniques that can be applied to the corresponding picture. For example, a picture can generally be assigned to any of the following picture types:

[0083] An intra picture (I picture) can 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 skilled in the art are aware of the variations of I pictures and their corresponding applications and features.

[0084] 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.

[0085] Bidirectionally predictive pictures (B pictures) can be encoded and decoded using intra prediction or inter prediction, which uses up to two motion vectors and reference indices to predict sample values ​​for each block. Similarly, multiple predictive pictures can use more than two reference pictures and associated metadata to reconstruct a single block.

[0086] A source picture is typically spatially subdivided into blocks of samples (e.g., blocks of 4×4, 8×8, 4×8, or 16×16 samples each) and coded block by block. These blocks may be predictively coded with reference to other (already coded) blocks, determined according to the coding allocation applied to the corresponding picture for that 'block'. For example, blocks of an I picture may be non-predictively coded, or they may be predictively coded (spatial or intra-predicted) with reference to already coded blocks of the same picture. Pixel blocks of a P picture may be predictively coded using spatial prediction or temporal prediction with reference to a previously coded reference picture. Blocks of a B picture may be predictively coded using spatial prediction or temporal prediction with reference to one or two previously coded reference pictures. Source pictures or intermediately processed pictures may be subdivided into other types of blocks for other purposes. The division of coding blocks and other types of blocks may or may not follow the same pattern, as described further below.

[0087] The video encoder (603) may perform encoding operations according to a predetermined video coding technique or standard, such as ITU-T Recommendation H.265. In operation, the video encoder (603) may perform various compression operations, including predictive coding operations that exploit temporal and spatial redundancy in the input video sequence. Accordingly, the encoded video data may conform to the syntax specified by the video coding technique or standard used.

[0088] In some example embodiments, the transmitter (640) may transmit additional data along with the encoded video. The source encoder (630) may include such data as part of the encoded video sequence. The additional data may include temporal / spatial / SNR enhancement layers, redundant pictures and slices, and other forms of redundant data, SEI messages, VUI parameter set fragments, and the like.

[0089] The captured video can be presented as a temporal sequence of multiple source pictures (video pictures). Intra-picture prediction (often shortened to intra prediction) exploits spatial correlations within a given picture, while inter-picture prediction exploits temporal or other correlations between pictures. For example, a particular picture being encoded / decoded can be divided into blocks, with the particular picture being encoded / decoded being referred to as the current picture. When a block in the current picture is similar to a reference block in a previously encoded and still buffered reference picture in the video, it can be encoded using a vector called a motion vector. The motion vector points to the reference block in a reference picture, and when multiple reference pictures are used, the motion vector can have a third dimension that identifies the reference picture.

[0090] In some example embodiments, bidirectional prediction techniques may be used for inter-picture prediction. According to this bidirectional prediction technique, two reference pictures are used, for example, a first reference picture and a second reference picture that both precede the current picture in the video in decoding order (but may be in the past or future, respectively, in display order). A block in the current picture may be encoded using 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 using a combination of the first and second reference blocks.

[0091] In addition, merge mode technology can be used in inter-picture prediction to improve coding efficiency.

[0092] According to some example embodiments disclosed in the present application, 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 divided into coding tree units (CTUs) for compression, and the CTUs in the picture have the same size, for example, 64×64 pixels, 32×32 pixels, or 16×16 pixels. In general, a CTU may include three parallel coding tree blocks (CTBs): one luminance CTB and two chrominance CTBs. Furthermore, each CTU may be split into one or more coding units (CUs) using a quadtree. For example, a 64×64 pixel CTU may be split into a 64×64 pixel CU, or four 32×32 pixel CUs, or sixteen 16×16 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 example implementations, each CU may be analyzed during the encoding process to determine a prediction type for the CU among various prediction types, for example, an inter-frame prediction type or an intra-frame prediction type. In addition, depending on temporal and / or spatial predictability, the CU may be split into one or more prediction units (PUs). Typically, each PU includes a luminance prediction block (PB) and two chrominance PBs. In an embodiment, the prediction operation in encoding (encoding / decoding) is performed in units of prediction blocks. Splitting a CU into PUs (or PBs with different color channels) may be performed in various spatial modes. A luminance or chrominance PB, for example, may include matrix values ​​of samples (e.g., luminance values), for example, 8×8 pixels, 16×16 pixels, 8×16 pixels, 16×8 pixels, and so on.

[0093] Figure 7 A diagram of a video encoder (703) according to another 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 to 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.

[0094] For example, the video encoder (703) receives a matrix of sample values ​​for a processing block, wherein the processing block is, for example, a prediction block of 8×8 samples, etc. The video encoder (703) uses, for example, rate-distortion optimization (RDO) to determine whether to use intra mode, inter mode, or bidirectional prediction mode to 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 use inter prediction or bidirectional prediction techniques to encode the processing block into an encoded picture, respectively. In some example embodiments, merge mode may be used as a submode of inter-picture prediction, wherein a motion vector is derived from one or more motion vector predictors without the aid of an encoded motion vector component external to the predictor. In certain other example embodiments, there may be a motion vector component applicable to the subject block. Accordingly, the video encoder (703) may include Figure 7 Components not explicitly shown in FIG, for example, a mode decision module for determining a prediction mode for a processing block.

[0095] exist Figure 7 In the example of , the video encoder (703) includes Figure 7 Shown are an inter-frame encoder (730), an intra-frame encoder (722), a residual calculator (723), a switch (726), a residual encoder (724), a general controller (721), and an entropy encoder (725) coupled together.

[0096] The inter-frame encoder (730) is configured to receive samples of a current block (e.g., a processing block), compare the block to 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 an embedded image. Figure 6 The decoding unit 633 in the example encoder 620 (e.g., Figure 7 The residual decoder 728, as described in further detail below, decodes the decoded reference pictures based on the encoded video information.

[0097] The intra-frame encoder (722) is configured to receive samples of a current block (e.g., a processing block), compare the block with previously encoded blocks in the same picture, generate quantization coefficients after transformation, and in some cases also generate intra-frame prediction information (e.g., intra-frame prediction direction information according to one or more intra-frame coding techniques). The intra-frame encoder (722) also calculates an intra-frame prediction result (e.g., a predicted block) based on the intra-frame prediction information and a reference block in the same picture.

[0098] The general controller (721) can be used to determine general control data and control other components of the video encoder (703) based on the general control data. In an embodiment, the general controller (721) determines a prediction mode for a block and provides a control signal to the switch (726) based on the prediction mode. For example, when the prediction mode is intra mode, the general controller (721) controls the switch (726) to select the intra mode result for use by the residual calculator (723) and controls the entropy encoder (725) to select intra prediction information and add the intra prediction information to the bitstream; and when the prediction mode for the block is inter mode, the general controller (721) controls the switch (726) to select the inter prediction result for use by the residual calculator (723) and controls the entropy encoder (725) to select inter prediction information and add the inter prediction information to the bitstream.

[0099] The residual calculator (723) can be used to calculate the difference (residual data) between the received block and the prediction result of the block selected from the intra-frame encoder (722) or the inter-frame encoder (730). The residual encoder (724) can be used to encode the residual data to generate transform coefficients. In an embodiment, the residual encoder (724) is used to convert the residual data from the time domain to the frequency domain and generate transform coefficients. The transform coefficients are then quantized to obtain quantized transform coefficients. For example, the video encoder (703) may also include a residual decoder (728). The residual decoder (728) is used to perform an inverse transform to generate decoded residual data. The decoded residual data can be used appropriately by the intra-frame encoder (722) and the inter-frame encoder (730). For example, the inter-frame encoder (730) can generate a decoded block based on the decoded residual data and inter-frame prediction information, and the intra-frame encoder (722) can generate a decoded block based on the decoded residual data and intra-frame prediction information. The decoded blocks are appropriately processed to generate decoded pictures, which may be buffered in memory circuitry (not shown) and used as reference pictures.

[0100] The entropy encoder (725) can be used to format the codestream to produce coded blocks and perform entropy encoding. The entropy encoder (725) is used to include various information in the codestream. For example, the entropy encoder (725) is used to obtain general control data, selected prediction information (e.g., intra-frame prediction information or inter-frame prediction information), residual information, and other appropriate information in the codestream. When encoding a block in inter-frame mode or the merge submode of bidirectional prediction mode, there is no residual information.

[0101] Figure 8A 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 image as part of an encoded video sequence and decode the encoded image to generate a reconstructed picture. In one example, the video decoder (810) may be used instead of Figure 4 A video decoder (410) is shown in the example.

[0102] exist Figure 8 In the example of , the video decoder (810) includes Figure 8 The example arrangement shown in FIG. 8 includes an entropy decoder ( 871 ), an inter decoder ( 880 ), a residual decoder ( 873 ), a reconstruction module ( 874 ), and an intra decoder ( 872 ) coupled together.

[0103] The entropy decoder (871) can be used to reconstruct certain symbols from the encoded picture, which represent syntax elements that constitute the encoded picture. Such symbols may include, for example, the mode of the block coding (e.g., intra mode, inter mode, bidirectional prediction mode, merge submode, or another submode), prediction information (e.g., intra prediction information or inter prediction information) that can identify certain samples or metadata for the intra decoder (872) or inter decoder (880) to use for prediction, respectively, residual information in the form of, for example, quantized transform coefficients, etc. In one example, when the prediction mode is inter prediction mode or bidirectional prediction mode, the inter prediction information is provided to the inter decoder (880); and when the prediction type is intra prediction type, the intra prediction information is provided to the intra decoder (872). The residual information can be inverse quantized and provided to the residual decoder (873).

[0104] The inter-frame decoder (880) may be configured to receive inter-frame prediction information and generate an inter-frame prediction result based on the inter-frame prediction information.

[0105] The intra decoder (872) may be configured to receive intra prediction information and generate a prediction result based on the intra prediction information.

[0106] The residual decoder (873) can be used to perform inverse quantization to extract dequantized transform coefficients and process the dequantized transform coefficients to convert the residual from the frequency domain to the spatial domain. The residual decoder (873) may also use certain control information (to obtain the quantizer parameter QP) that may be provided by the entropy decoder (871) (the data path is not shown because this may only be low-level control information).

[0107] The reconstruction module (874) can be used 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) in the spatial domain to form a reconstructed block, which forms part of a reconstructed picture, which in turn can be part of a reconstructed video. It should be noted that other suitable operations such as deblocking operations can be performed to improve visual quality.

[0108] It should be noted that the video encoder (403), video encoder (603), and video encoder (703), as well as the video decoder (410), video decoder (510), and video decoder (810) may be implemented using any suitable technology. In one embodiment, the video encoder (403), video encoder (603), and video encoder (703), as well as the video decoder (410), video decoder (510), and video decoder (810) may be implemented using one or more integrated circuits. In another embodiment, the video encoder (403), video encoder (603), and video encoder (603), as well as the video decoder (410), video decoder (510), and video decoder (810) may be implemented using one or more processors executing software instructions.

[0109] Turning to block partitioning for encoding and decoding, partitioning can generally start from basic blocks 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 dividing or partitioning the basic blocks according to any example partitioning process or other processes described below or their combination, a final set of partitions or coding blocks can be obtained. Each of these partitions can be at one of the various partition levels in the partition hierarchy and can have various shapes. Each of the partitions can be called a coding block (CB). For the various example partitioning implementations further described below, each resulting CB can have any allowed size and partition level. Such partitions are called coding blocks because they can form some units for which some basic encoding / decoding decisions can be made, and the encoding / decoding parameters of these units can be optimized, determined, and signaled in the encoded video stream. 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 for each color can be called a coding block tree (CBT).

[0110] The coding blocks of all color channels may be collectively referred to as a coding unit (CU). The hierarchical structure for all color channels may be collectively referred to as a coding tree unit (CTU). The partitioning scheme or structure for each color channel in a CTU may be the same or different.

[0111] In some embodiments, the partition tree schemes or structures used for the luma channel and the chroma channels may not necessarily be the same. In other words, the luma channel and the chroma channel may have separate coding tree structures or modes. Further, whether the luma channel and the chroma channel use the same or different coding partition tree structures and the actual coding partition tree structure to be used may depend on whether the stripe being coded is a P stripe, a B stripe, or an I stripe. For example, for an I stripe, the chroma channel and the luma channel may have separate coding partition tree structures or coding partition tree structure modes, while for a P stripe or a B stripe, the luma channel and the chroma channels may share the same coding partition tree scheme. When separate coding partition tree structures or modes are 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.

[0112] In some example embodiments, a predetermined partitioning scheme may be applied to a basic block. Figure 9 As shown, the example 4-way partition tree can start from a first predefined level (e.g., 64×64 block level or other size as a basic block size), and the basic block can be partitioned hierarchically down to a predefined lowest level (e.g., 4×4 level). For example, the basic block can go through four predefined partitioning options or modes indicated by 902, 904, 906 and 908, where the partition designated as R allows for recursive partitioning because it can be repeated at a lower ratio. Figure 9 In some embodiments, the same partitioning options indicated in , up to the lowest level (e.g., 4×4 level). Figure 9 Additional restrictions apply to partitioning schemes. Figure 9 In the implementation of , rectangular partitions (e.g., 1:2 / 2:1 rectangular partitions) may be allowed, but they may not be recursive, while square partitions may be allowed to be recursive. If necessary, follow Figure 9 The recursive partitioning of generates the final set of coding blocks. The coding tree depth can be further defined to indicate the partition depth from the root node or root block. For example, the coding tree depth of the root node or root block (e.g., 64×64 block) can be set to 0, and the root block is Figure 9 After being further partitioned once, the coding tree depth increases by 1. For the above scheme, the maximum level or deepest level of the minimum partition from 64×64 basic block to 4×4 will be 4 (starting from level 0). This partitioning scheme can be applied to one or more color channels. It can be followed Figure 9 The scheme partitions each color channel independently (e.g., a partitioning pattern or option in a predefined pattern may be determined independently for each color channel at each hierarchical level). Optionally, two or more color channels may share Figure 9The same hierarchical mode tree (eg, the same partitioning mode or option in the predefined modes can be selected for two or more color channels at each hierarchical level).

[0113] Figure 10 Another example predefined partitioning scheme that allows the use of recursive partitioning to form a partition tree is shown. Figure 10 As shown in , an example 10-way partitioning structure or pattern may be predefined. A root block may start at a predefined level (eg, from a basic block at a 128x128 level or a 64x64 level). Figure 10 Example partition structures include various 2:1 / 1:2 and 4:1 / 1:4 rectangular partitions. Figure 10 The partition type with three sub-partitions indicated as 1002, 1004, 1006 and 1008 in the second row of FIG 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, a top T-type, a right T-type and a bottom T-type. In some example embodiments, Figure 10 None of the rectangular partitions are allowed to be further subdivided. The coding tree depth can be further defined to indicate the partition depth from the root node or root block. For example, the coding tree depth of the root node or root block (e.g., 128×128 block) can be set to 0, and the root block is Figure 10 After being further split once, the coding tree depth increases by 1. In some embodiments, all square partitions in 1010 may only be allowed to follow Figure 10 The pattern recursively partitions to the next level of the partition tree. In other words, for the square partitions 1002, 1004, 1006, and 1008 within the T-pattern, recursive partitioning may not be allowed. If necessary, follow Figure 10 The recursive partitioning process generates the final set of coding blocks. Such a scheme can be applied to one or more color channels. In some embodiments, more flexibility can be added to the use of partitions below the 8×8 level. For example, 2×2 chroma inter-frame prediction can be used in some cases.

[0114] In some other example embodiments for coding block partitioning, a quadtree structure can be used to partition a basic block or intermediate block into quadtree partitions. This quadtree partitioning can be applied hierarchically and recursively to any square partition. Further quadtree partitioning of a basic block, intermediate block, or partition can be adapted to the various local characteristics of the basic block or intermediate block / partition. The quadtree partitioning can be further adjusted at picture boundaries. For example, implicit quadtree partitioning can be performed at picture boundaries so that a block will continue to be quadtree partitioned until its size fits within the picture boundary.

[0115] In some other example embodiments, a hierarchical binary partitioning scheme can be used starting from a basic block. In this scheme, a basic block or an intermediate block can be partitioned into two partitions. The binary partitioning can be horizontal or vertical. For example, horizontal binary partitioning can split a basic block or an intermediate block into equal left and right partitions. Similarly, 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. A decision can be made at each basic block or intermediate block whether the binary partitioning scheme should be continued. If the scheme is continued, a decision is made whether horizontal binary partitioning or vertical binary partitioning should be used. In some embodiments, further partitioning can stop at a predefined minimum partition size (in one or two dimensions). Optionally, further partitioning can stop once a predefined partitioning level or depth starting from the basic block is reached. In some embodiments, the aspect ratio of the partitions can be restricted. For example, the aspect ratio of the partitions can be no less than 1:4 (or greater than 4:1). In this way, a vertical stripe partition having 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 having a vertical to horizontal aspect ratio of 2:1.

[0116] In some other examples, Figure 13 As shown, the three-pronged partitioning scheme can be used to partition basic blocks or any intermediate blocks. The three-pronged pattern can be as follows Figure 13 1302 in vertical implementation, or as shown in Figure 13 1304 is implemented horizontally. Figure 13 An example vertical or horizontal partition ratio is shown as 1:2:1, but other ratios can be predefined. In some embodiments, two or more different ratios can be predefined. This three-way partitioning scheme can be used to compensate for quadtree or binary partitioning structures because the three-way partitioning can capture objects located at the center of the block in one continuous partition, while quadtree and binary trees always partition along the center of the block, thus dividing the objects into separate partitions. In some embodiments, the width and height of the partitions of the example three-way tree are always powers of 2 to avoid additional transformations.

[0117] 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 the basic block into a quadtree-binary tree (QTBT) structure. In this scheme, the basic block or intermediate block / partition can be quadtree-partitioned or binary-partitioned, subject to a specified predefined set of conditions. Figure 14 A specific example is illustrated in . Figure 14In the example of FIG, a basic block is first quadtree-partitioned into four partitions, as shown in 1402, 1404, 1406, and 1408. Thereafter, each resulting partition is either quadtree-partitioned into four additional partitions (such as 1408), or binary-partitioned at the next level into two additional partitions (horizontally or vertically, such as 1402 or 1406, for example, both are symmetrical), or not partitioned (such as 1404). For square partitions, binary or quadtree partitioning can be recursively allowed, as shown in the overall example partitioning pattern 1410 and the corresponding tree structure / representation in 1420, where solid lines represent quadtree partitioning and dashed lines represent binary partitioning. A flag can be used for each binary partition node (non-leaf binary partition) to indicate whether the binary partitioning is horizontal or vertical. For example, as shown in 1420, consistent with the partitioning structure of 1410, a flag of "0" can indicate a horizontal binary partitioning and a flag of "1" can indicate a vertical binary partitioning. For quadtree partitioning, there is no need to indicate the partition type, because quadtree partitioning always splits the block or partition horizontally and vertically to produce 4 sub-blocks / partitions of equal size. In some embodiments, the flag "1" can indicate horizontal binary partitioning, and the flag "0" can indicate vertical binary partitioning.

[0118] In some example implementations of QTBT, the quadtree and binary split rule set may be represented by the following predefined parameters and their associated corresponding functions:

[0119] –CTU size: the root node size of the quadtree (the size of the basic block)

[0120] –MinQTSize: Minimum allowed quadtree leaf node size

[0121] –MaxBTSize: Maximum allowed binary tree root node size

[0122] –MaxBTDepth: Maximum allowed binary tree depth

[0123] –MinBTSize: Minimum allowed binary tree leaf node size

[0124] In some example implementations of the QTBT partition structure, the CTU size can be set to 128×128 luma samples with two corresponding 64×64 chroma sample blocks (when example chroma subsampling is considered and used), MinQTSize can be set to 16×16, MaxBTSize can be set to 64×64, MinBTSize (for both 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. The size of the quadtree leaf node can be from its 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 by the binary tree first because the size exceeds the MaxBTSize (i.e., 64×64). Otherwise, nodes that do not exceed the MaxBTSize can be partitioned by the binary tree. In Figure 14 In the example, the basic block is 128×128. According to a 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 resulting partitions is 64×64, not exceeding MaxBTSize, and can be further quadtree or binary tree split at level 1. The process continues. When the binary tree depth reaches MaxBTDepth (i.e., 4), further splitting can be disregarded. When the width of the binary tree node is equal to MinBTSize (i.e., 4), further horizontal splitting can be disregarded. Similarly, when the height of the binary tree node is equal to MinBTSize, further vertical splitting is disregarded.

[0125] In some example embodiments, the above 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 slices and B slices, the luma CTB and chroma CTB 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 for the luma component or coding blocks for two chroma components, and a CU in a P slice or a B slice can consist of coding blocks for all three color components.

[0126] In some other embodiments, the QTBT scheme can be supplemented with the above-mentioned three-pronged scheme. This embodiment can be called a multi-type-tree (MTT) structure. For example, in addition to the binary split of the node, you can choose Figure 13In some embodiments, only square nodes can be trifurcated. An additional flag can be used to indicate whether the trifurcated partition is horizontal or vertical.

[0127] The design of two or more levels of trees, such as the QTBT implementation and the QTBT implementation supplemented by ternary partitioning, can 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 trade-off can be made by using multiple types (T) while reducing the depth (D).

[0128] In some embodiments, the CB can be further partitioned. For example, for the purpose of intra-frame prediction or inter-frame prediction during the encoding and decoding process, the CB can be further partitioned into multiple prediction blocks (PBs). In other words, the CB can be further divided into different sub-partitions, in which separate prediction decisions / configurations can be made. At the same time, for the purpose of depicting the level of transformation or inverse transformation performed on the video data, the CB can be further partitioned into multiple transform blocks (TBs). The partitioning schemes of the CB to PBs and TBs can be the same or different. For example, each partitioning scheme can be performed using its own process based on various characteristics of the video data. In some example embodiments, the PB and TB partitioning schemes can be independent. In some other example embodiments, the PB and TB partitioning schemes and boundaries can be related. In some embodiments, for example, the TB can be partitioned after the PB partitioning, specifically, each PB (after the partitioning of the coding block is determined) can then be further partitioned into one or more TBs. For example, in some embodiments, the PB can be split into one, two, four, or other number of TBs.

[0129] In some embodiments, in order to partition a basic block into coding blocks and further into prediction blocks and / or transform blocks, the luma channel and the chroma channels may be processed differently. For example, in some embodiments, partitioning of a coding block into prediction blocks and / or transform blocks may be allowed for the luma channel, while partitioning of a coding block into prediction blocks and / or transform blocks may not be allowed for one or more chroma channels. In such embodiments, the transform and / or prediction of the luma block may therefore be performed only at the coding block level. For another example, the minimum transform block size for the luma channel and one or more chroma channels may be different, for example, the coding block for the luma channel may be allowed to be partitioned into transform blocks and / or prediction blocks that are smaller than those for the chroma channels. For another example, the maximum depth for partitioning a coding block into transform blocks and / or prediction blocks may be different between the luma channel and the chroma channels, for example, the coding block for the luma channel may be allowed to be partitioned into transform blocks and / or prediction blocks that are deeper than those for the one or more chroma channels. As a specific example, a luma coding block can be partitioned into transform blocks of multiple sizes, which can be represented by recursive partitioning down to up to 2 levels, and can 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 is allowed.

[0130] In some example embodiments 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.

[0131] Partitioning a coding block (or prediction block) into transform blocks can be implemented in various example schemes, including but not limited to recursively or non-recursively quadtree partitioning and predefined pattern partitioning, and additionally considering transform blocks at the boundaries of the coding block or prediction block. In general, the resulting transform blocks may be at different partitioning levels, may not be of the same size, and may not need to be square in shape (e.g., they may be rectangular with some allowed size and aspect ratio). Figure 15 、 Figure 16 and Figure 17 Other examples are described in more detail.

[0132] However, in some other embodiments, the CB obtained via any of the above partitioning schemes can be used as a basic block or minimum coding block for prediction and / or transformation. In other words, no further segmentation is performed for the purpose of performing inter-frame prediction / intra-frame prediction and / or for the purpose of transformation. For example, the CB obtained from the above QTBT scheme can be directly used as a unit for performing prediction. Specifically, this QTBT structure removes the concept of multiple partition types, that is, the distinction between CU, PU and TU is removed, providing greater flexibility for the CU / CB partition shape as described above. In this QTBT block structure, the CU / CB can have a square or rectangular shape. The leaf nodes of this QTBT are used as units of prediction and transformation processing without any further partitioning. This means that the CU, PU and TU have the same block size in this example QTBT coding block structure.

[0133] The above various CB partitioning schemes and further partitioning of CB into PB and / or TB (excluding PB / TB partitioning) can be combined in any manner.The following specific implementations are provided as non-limiting examples.

[0134] The following describes a specific example implementation of coding block and transform block partitioning. In this example implementation, recursive quadtree partitioning or the predefined partitioning patterns described above (e.g. Figure 9 and Figure 10 The basic block is partitioned into coding blocks according to the pattern in (in). At each level, whether further quadtree partitioning of a particular partition should continue can be determined by local video data characteristics. The resulting CBs can be at various quadtree partitioning levels and have various sizes. A decision can be made at the CB level (or CU level, for all three color channels) as to whether to use inter-picture (temporal) prediction or intra-picture (spatial) prediction to encode the picture area. Each CB can be further partitioned into one, two, four or other number of PBs according to a predefined PB partitioning type. Within a PB, the same prediction process can be applied, and relevant information can be transmitted to the decoder based on the PB. After obtaining the residual block by applying the prediction process based on the PB partitioning type, the CB can be partitioned into TBs according to another quadtree structure similar to the coding tree for the CB. In this particular embodiment, the CB or TB can be, but is not necessarily limited to, a square shape. Further, in this particular example, the PB can be a square or rectangular shape for inter prediction and can be only a square for intra prediction. The coding block can be partitioned into, for example, four square TBs. Each TB can be further recursively partitioned (using quadtree partitioning) into smaller TBs, called residual quadtrees (RQTs).

[0135] Another example embodiment for partitioning a basic block into CBs, PBs, and / or TBs is further described below. For example, instead of using a quadtree with nested multi-type trees such as a ternary partitioning segment structure (e.g., a QTBT or a QTBT with ternary partitioning as described above), a quadtree with nested multi-type trees may be used. Figure 9 or Figure 10 The multi-partition unit type shown. The distinction between CB, PB and TB can be abandoned (i.e., partitioning CB into PB and / or TB, and partitioning PB into TB) unless a CB with a size that is too large for the maximum transform length is required, where such a CB may need to be further split. This example partitioning scheme can be designed to provide more flexibility for the CB partition shape so that both prediction and transformation can be performed at the CB level without further partitioning. In this coding tree structure, the CB can have a square or rectangular shape. Specifically, the coding tree block (CTB) can first be partitioned by a quadtree structure. Then, the quadtree leaf nodes can be further partitioned by a nested multi-type tree structure. Figure 11 An example of a nested multi-type tree structure using binary or ternary partitioning is shown in FIG. Figure 11 The example multi-type tree structure includes four split types, called 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 CBs then correspond to the leaves of the multi-type tree. In this example embodiment, unless the CB is too large for the maximum transform length, the segment is used for prediction and transform processing without any further partitioning. This means that in most cases, the CBs, PBs and TBs have the same block size in a quadtree with a nested multi-type tree coding block structure. An exception occurs when the maximum supported transform length is less than the width or height of the color components of the CB. In some embodiments, in addition to binary or ternary splits, Figure 11 The nested pattern can further include quadtree partitioning.

[0136] Figure 12 A specific example of a quadtree with nested multi-type tree coding block structure (including quadtree, binary and ternary split options) for a basic block is shown. In more detail, Figure 12 The basic block 1200 is shown to be divided into four square partitions 1202, 1204, 1206 and 1208 by a quadtree. Further use is made for each quadtree partition. Figure 11 The multi-type tree structure and the decision of the quadtree for further segmentation. Figure 12In the example, partition 1204 is not further split. Each of partitions 1202 and 1208 uses another quadtree split. For partition 1202, the upper left, upper right, lower left and lower right partitions of the second level quadtree split use the third level of quadtree split, Figure 11 Horizontal binary split 1104, non-split and Figure 11 The horizontal three-branch partition 1108 is divided into two parts. Partition 1208 adopts another quadtree partition, and the upper left, upper right, lower left and lower right partitions of the second level quadtree partition are respectively divided into two parts. Figure 11 The third level of vertical trifurcated segmentation 1106 is segmented, non-segmented, non-segmented and Figure 11 The horizontal binary partition 1104. The two sub-partitions of the third level upper left partition 1208 are respectively based on Figure 11 The horizontal binary partition 1104 and the horizontal trifurcated partition 1108 are further divided. The partition 1206 adopts the following Figure 11 The second level segmentation pattern of the vertical binary segmentation 1102 is divided into two partitions, which are divided into two partitions in the third level according to Figure 11 The horizontal trifurcated segmentation 1108 and the vertical binary segmentation 1102 are further segmented. Figure 11 1104, a fourth level of segmentation is further applied to one of them.

[0137] For the specific example above, the maximum luma transform size may be 64×64, and the maximum supported chroma transform size may be different from luma, for example, 32×32. Figure 12 The example CB in is usually not further split into smaller PBs and / or TBs. 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 can be automatically split in the horizontal and / or vertical directions to meet the transform size limit in that direction.

[0138] In the above specific example for partitioning basic blocks into CBs, 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 slices and B slices, the luma CTB and chroma CTB 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 is partitioned into chroma CBs through another coding tree structure. This means that a CU in an I slice can consist of coding blocks for the luma component or coding blocks for two chroma components, and a CU in a P slice or B slice always consists of coding blocks for all three color components unless the video is monochrome.

[0139] 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 embodiments for partitioning a coding block or prediction block into transform blocks and the encoding order of the transform blocks are further described in detail below. In some example embodiments, as described above, transform partitioning can support transform blocks of various shapes (e.g., 1:1 (square), 1:2 / 2:1, and 1:4 / 4:1), where transform block sizes range from, for example, 4×4 to 64×64. In some embodiments, if the coding block is less than or equal to 64×64, transform block partitioning can be applied only to the luma component, so that for chroma blocks, the transform block size is the same as the coding block size. Otherwise, if the coding block width or height is greater than 64, both luma and chroma coding blocks can be implicitly split into multiples of min(W,64) x min(H,64) and min(W,32) x min(H,32) transform blocks, respectively.

[0140] In some example embodiments of transform block partitioning, for both intra-coded blocks and inter-coded blocks, the coding block can be further partitioned into multiple transform blocks with a partition depth of up to a predefined number of levels (e.g., 2 levels). The transform block partition depth and partition size can be related. For some example embodiments, the mapping from the transform size of the current depth to the transform size of the next depth is shown in Table 1 below.

[0141] Table 1: Change partition size settings

[0142]

[0143] Based on the example mapping in Table 1, for a 1:1 square block, the next level of transform partitioning can create four 1:1 square sub-transform blocks. Transform partitioning can, for example, stop at 4×4. In this way, the transform size of 4×4 at the current depth corresponds to the same size of 4×4 at the next depth. In the example in Table 1, for a 1:2 / 2:1 non-square block, the next level of transform partitioning can create two 1:1 square sub-transform blocks, while for a 1:4 / 4:1 non-square block, the next level of transform partitioning can create two 1:2 / 2:1 sub-transform blocks.

[0144] In some example embodiments, for the luma component of an intra-coded block, additional restrictions may be applied to the transform block partitioning. For example, for each level of transform partitioning, all its sub-transform blocks may be constrained to have equal sizes. For example, for a 32×16 coding block, level 1 transform partitioning creates two 16×16 sub-transform blocks, and level 2 transform partitioning creates eight 8×8 sub-transform blocks. In other words, the second level partitioning must be applied to all first level sub-blocks to keep the transform unit sizes equal. Figure 151 shows an example of transform block partitioning for an intra-coded square block according to Table 1, and the coding order illustrated by the arrows. Specifically, 1502 shows a square coding block. 1504 shows a first level partitioning into 4 equal-sized transform blocks according to Table 1, with the coding order indicated by the arrows. 1506 shows a second level partitioning of all first level equal-sized blocks into 16 equal-sized transform blocks according to Table 1, with the coding order indicated by the arrows. In some example embodiments, the above restrictions on intra coding may not apply to the luma component of an inter-coded block. For example, after the first level transform partitioning, any of the sub-transform blocks may be further partitioned independently by one more level. Thus, the resulting transform blocks may or may not have the same size. Figure 16 An example of partitioning an inter-coded block into transforms with their coding order is shown in . Figure 16 In the example of FIG1 , the inter-frame coded block 1602 is divided into two levels of transform blocks according to Table 1. At the first level, the inter-frame coded block is divided into four transform blocks of equal size. Then, as shown in 1604, only one of the four transform blocks (not all) is further divided into four sub-transform blocks, resulting in a total of 7 transform blocks with two different sizes. The example coding order of these 7 transform blocks is represented by Figure 16 The arrow in 1604 is shown.

[0145] In some example embodiments, for one or more chroma components, some additional restrictions on the transform block may be applied. For example, for one or more 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.

[0146] In some other example embodiments, for coding blocks with a width (W) or height (H) greater than 64, both luma coding blocks 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.

[0147] Figure 17 Another optional example scheme for partitioning a coding block or prediction block into transform blocks is further shown. Figure 17 As shown in , 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. Figure 17 In the specific example shown in , one of six example partition types can be applied to split the coding block into various numbers of transform blocks. This scheme for generating transform block partitions can be applied to either the coding block or the prediction block.

[0148] In more detail, Figure 17 The partitioning scheme of provides up to 6 example partition types for any given transform type (transform type refers to, for example, the type of primary transform, such as ADST and others). In this scheme, a transform partition type can be assigned to each coding block or prediction block based on, for example, rate-distortion cost. In one 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. Figure 17 As shown in the 6 transform partition types shown, a specific transform partition type can correspond to a transform block partition size and a partition mode. The correspondence between various transform types and various transform partition types can be predefined. An example is shown below, where the capitalized mark indicates the transform partition type that can be assigned to a coding block or prediction block based on the rate-distortion cost:

[0149] PARTITION_NONE: Allocate a transform size equal to the block size.

[0150] PARTITION_SPLIT: allocates a transform size whose width is 1 / 2 of the block size and whose height is 1 / 2 of the block size.

[0151] PARTITION_HORZ: Allocate a transform size whose width is the same as the block size and whose height is 1 / 2 of the block size.

[0152] PARTITION_VERT: Allocate a transform size whose width is 1 / 2 the block size and whose height is the same as the block size.

[0153] PARTITION_HORZ4: Allocates a transform size whose width is the same as the block size and whose height is 1 / 4 of the block size.

[0154] PARTITION_VERT4: Allocates a transform size whose width is 1 / 4 of the block size and whose height is the same as the block size.

[0155] In the above example, if Figure 17 The transform partition types shown all include a uniform transform size for the transform blocks after partitioning. This is merely an example and not a limitation. In some other embodiments, mixed transform block sizes may be used for the transform blocks after partitioning for a particular partition type (or mode).

[0156] The PB (or CB, also referred to as a PB when not further partitioned into prediction blocks) obtained from any of the above partitioning schemes can then become individual blocks for encoding via intra-frame prediction or inter-frame prediction. For inter-frame prediction for the current PB, the residual between the current block and the prediction block can be generated, encoded, and included in the encoded bitstream.

[0157] Inter-frame prediction can be implemented, for example, in a single reference mode or a composite reference mode. In some embodiments, a skip flag can be initially included in the codestream for the current block (or at a higher level) to indicate whether the current block is inter-coded and not skipped. If the current block is inter-coded, another flag can be further included in the codestream as a signal to indicate whether a single reference mode or a composite reference mode is used for prediction of the current block. For a single reference mode, a single reference block can be used to generate a prediction block for the current block. For a composite reference mode, two or more reference blocks can be used (for example), with a weighted average to generate a prediction block. A composite reference mode can refer to a mode with more than one reference, a mode with two references, or a mode with multiple references. One or more reference blocks can be identified using a reference frame index or multiple reference frame indices in addition to a corresponding motion vector or motion vectors, wherein the motion vector or motion vectors indicate one or more shifts in position (for example, in horizontal and vertical pixels) between the one or more reference blocks and the current block. For example, in single reference mode, the inter prediction block for the current block can be generated from a single reference block identified as a prediction block by a motion vector in a reference frame, while for composite reference mode, the prediction block can be generated by a weighted average of two reference blocks in two reference frames indicated by two reference frame indices and two corresponding motion vectors. One or more motion vectors can be encoded and included in the codestream in various ways.

[0158] In some embodiments, the encoding or decoding system may maintain a decoded picture buffer (DPB). Some images / pictures may be held in the DPB awaiting display (in the decoding system), and some images / pictures in the DPB may be used as reference frames for inter-frame prediction (in the decoding system or encoding system). In some embodiments, reference frames in the DPB may be marked as short-term references or long-term references for the current image being encoded or decoded. For example, short-term reference frames may include frames used for inter-frame prediction of blocks in the current frame or in a predefined number (e.g., two) of subsequent video frames closest to the current frame in decoding order. Long-term reference frames may include frames in the DPB that may be used to predict image blocks in frames that are more than a predefined number of frames away from the current frame in decoding order. Information regarding this labeling of short-term and long-term reference frames may be referred to as a reference picture set (RPS) and may be added to the header of each frame in the encoded codestream. Each frame in the encoded video stream may be identified by a picture order count (POC), which is numbered in an absolute manner according to the playback sequence or relative to a group of pictures, for example, starting with an I frame.

[0159] In some example embodiments, one or more reference picture lists may be formed based on information in the RPS, containing identifiers of short-term reference frames and long-term reference frames for inter-frame prediction. For example, a single picture reference list may be formed for unidirectional inter-frame prediction, denoted as L0 reference (or reference list 0), while two picture reference lists may be formed for bidirectional inter-frame prediction, denoted as L0 (or reference list 0) and L1 (or reference list 1) for each of the two prediction directions. The reference frames included in the L0 and L1 lists may be ordered in various predetermined ways. The lengths of the L0 and L1 lists may be signaled in the video bitstream. When multiple references used to generate a prediction block by weighted averaging in a composite prediction mode are on the same side of the block to be predicted, unidirectional inter-frame prediction may be in single reference mode or in composite reference mode. Bidirectional inter-frame prediction may be only a composite mode because bidirectional inter-frame prediction involves at least two reference blocks.

[0160] In some embodiments, merge mode (MM) for inter-frame prediction may be implemented. Generally, with merge mode, a motion vector in a single reference prediction or one or more motion vectors in a composite reference prediction for the current PB may be derived from one or more other motion vectors, rather than being independently calculated and signaled. For example, in the encoding system, one or more current motion vectors for the current PB may be represented by one or more differences between the one or more current motion vectors and one or more other encoded motion vectors (referred to as reference motion vectors). One or more of these differences, rather than the entire one or more current motion vectors, may be encoded and included in the bitstream and may be linked to one or more reference motion vectors. Accordingly, in the decoding system, one or more motion vectors corresponding to the current PB may be derived based on the one or more decoded motion vector differences and the one or more decoded reference motion vectors to which they are linked. As a specific form of general merge mode (MM) inter-frame prediction, this inter-frame prediction based on one or more motion vector differences may be referred to as merge mode with motion vector differences (MMVD). Therefore, MM in general, or MMVD in particular, may be implemented to exploit correlations between motion vectors associated with different PBs to improve coding efficiency. For example, adjacent PBs may have similar motion vectors, and thus the MVD may be small and may be efficiently encoded.For another example, motion vectors may be associated temporally (between frames) with blocks that are similarly located / positioned in space.

[0161] In some example embodiments, an MM flag may be included in the bitstream during the encoding process to indicate whether the current PB is in merge mode. Additionally, or alternatively, an MMVD flag may be included in the bitstream and signaled during the encoding process to indicate whether the current PB is in MMVD mode. The MM and / or MMVD flags or indicators may be provided at the PB level, CB level, CU level, CTB level, CTU level, slice level, picture level, etc. For a specific example, both the MM flag and the MMVD flag may be included for the current CU, and the MMVD flag may be signaled immediately after the skip flag and the MM flag to specify whether the MMVD mode is used for the current CU.

[0162] In some example embodiments of MMVD, a list of reference motion vector (RMV) or MV predictor candidates for motion vector prediction may be formed for the block being predicted. The list of RMV candidates may contain a predetermined number (e.g., 2) of MV predictor candidate blocks whose motion vectors may be used to predict the current motion vector. The RMV candidate blocks may include blocks selected from neighboring blocks in the same frame and / or temporal blocks (e.g., blocks at the same location in the previous or next frame of the current frame). These options represent blocks that may have similar or identical motion vectors as the current block at a spatial or temporal location relative to the current block. The size of the list of MV predictor candidates may be predetermined. For example, the list may contain two or more candidates. To be on the list of RMV candidates, for example, a candidate block may need to have the same reference frame (or frames) as the current block, must exist (e.g., when the current block is near a frame edge, a boundary check may need to be performed), and must have been encoded during the encoding process and / or decoded during the decoding process. In some embodiments, the list of merge candidates may be populated first with spatially adjacent blocks (scanned in a specific predefined order) (if available and the above conditions are met), and then with temporal blocks (if space is still available in the list). For example, adjacent RMV candidate blocks may be selected from the left block and the top block of the current block. The list of RMV predictor candidates may be dynamically formed as a dynamic reference list (DRL) at various levels (sequence, picture, frame, slice, super block, etc.). The DRL may be signaled in the bitstream.

[0163] In some embodiments, the actual MV predictor candidate used as the reference motion vector for predicting the motion vector of the current block can be signaled. In the case where the RMV candidate list contains two candidates, a 1-bit flag called the merge candidate flag can be used to indicate the selection of the reference merge candidate. For the current block predicted in composite mode, each of the multiple motion vectors predicted using the MV predictor can be associated with a reference motion vector from the merge candidate list. The encoder can determine which RMV candidate more closely predicts the current coding block and signal this selection as an index to the DRL.

[0164] In some example embodiments of MMVD, after an RMV candidate is selected and used as a base motion vector predictor for a motion vector to be predicted, a motion vector difference (MVD or delta MV, representing the difference between the motion vector to be predicted and the reference candidate motion vector) may be calculated in the encoding system. This MVD may include information indicating the magnitude of the MV difference and the direction of the MV difference, both of which may be signaled in the bitstream. The motion difference magnitude and the motion difference direction may be signaled in various ways.

[0165] In some example implementations of the MMVD, a distance index can be used to specify the magnitude information of the motion vector difference and indicate one of a set of predefined offsets representing the predefined motion vector difference from the starting point (reference motion vector). The MV offset according to the signaled index can then be added to the horizontal component or vertical component of the starting (reference) motion vector. Whether the horizontal component or vertical component of the reference motion vector should be offset can be determined by the direction information of the MVD. An example predefined relationship between the distance index and the predefined offset is specified in Table 2.

[0166] Table 2 - Example relationship between distance index and predefined MV offsets

[0167]

[0168] In some example embodiments of the MMVD, a direction index may be further signaled and used to indicate the direction of the MVD relative to the reference motion vector. In some embodiments, the direction may be restricted to either the horizontal or vertical direction. An example 2-bit direction index is shown in Table 3. In the example of Table 3, the interpretation of the MVD may vary depending on the information of the start / reference MV. For example, when the start / reference MV corresponds to a single-prediction block or to a dual-prediction block and the two reference frame lists point to the same side of the current picture (i.e., the POCs of both reference pictures are greater than the POC of the current picture, or are less than the POC of the current picture), the sign in Table 3 may specify the sign (direction) of the MV offset added to the start / reference MV. When the start / reference MV corresponds to a bidirectionally predicted block and the reference pictures are on different sides of the current picture (i.e., the POC of one reference picture is greater than the POC of the current picture, and the POC of the other reference picture is less than the POC of the current picture), and the difference between the reference POC in picture reference list 0 and the current frame is greater than the difference between the reference POC in picture reference list 1 and the current frame, the symbols in Table 3 may specify the sign of the MV offset added to the reference MV corresponding to the reference picture in picture reference list 0, and the sign of the offset for the MV corresponding to the reference picture in picture reference list 1 may have an opposite value (opposite sign for the offset). Otherwise, if the difference between the reference POC in picture reference list 1 and the current frame is greater than the difference between the reference POC in picture reference list 0 and the current frame, the symbols in Table 3 may specify the sign of the MV offset added to the reference MV associated with picture reference list 1, and the sign of the offset for the reference MV associated with picture reference list 0 has an opposite value.

[0169] Table 3 - Example implementation of signs for MV offsets specified by direction index

[0170] Direction IDX 00 01 10 11 X axis (horizontal) + - not applicable not applicable Y axis (vertical) not applicable not applicable + -

[0171] In some example embodiments, the MVD may be scaled based on the difference in POC in each direction. If the difference in POC in both lists is the same, no scaling is required. Otherwise, if the difference in POC in reference list 0 is greater than the difference in POC in reference list 1, the MVD for reference list 1 is scaled. If the POC difference for reference list 1 is greater than the POC difference for reference list 0, the MVD for list 0 may be scaled in the same manner. If the starting MV is uni-predicted, the MVD is added to the available or reference MV.

[0172] In some example embodiments of MVD encoding and signaling for bidirectional composite prediction, in addition to or as an alternative to separately encoding and signaling two MVDs, symmetric MVD encoding can be implemented such that only one MVD needs to be signaled, while the other MVD can be derived from the signaled MVD. In such an embodiment, motion information including the reference picture indices for both List-0 and List-1 is signaled. However, only the MVD associated with, for example, Reference List-0 is signaled, and the MVD associated with Reference List-1 is derived without signaling. Specifically, at the slice level, a flag can be included in the codestream, called "mvd_l1_zero_flag," to indicate whether Reference List-1 is not signaled in the codestream. If this flag is 1, indicating that Reference List-1 is equal to 0 (and therefore not signaled), then a bidirectional prediction flag, called "BiDirPredFlag," can be set to 0, meaning that no bidirectional prediction is present. Otherwise, if mvd_l1_zero_flag is zero, BiDirPredFlag may be set to 1 if the nearest reference picture in list-0 and the nearest reference picture in list-1 form a forward and backward reference picture pair or a backward and forward reference picture pair, and both list-0 and list-1 reference pictures are short-term reference pictures. Otherwise, BiDirPredFlag is set to 0. BiDirPredFlag of 1 may indicate that the symmetric mode flag is additionally signaled in the bitstream. When BiDirPredFlag is 1, the decoder may extract the symmetric mode flag from the bitstream. For example, the symmetric mode flag may be signaled (if necessary) at the CU level, and it may indicate whether the symmetric MVD coding mode is being used for the corresponding CU. When the symmetric mode flag is 1, it indicates the use of symmetric MVD coding mode, and only the reference picture indices of both list-0 and list-1 (referred to as "mvp_l0_flag" and "mvp_l1_flag") are signaled with the MVD associated with list-0 (referred to as "MVD0"), and the other motion vector difference "MVD1" will be derived rather than signaled. For example, MVD1 can be derived as -MVD0. Thus, only one MVD is signaled in the example symmetric MVD mode. In some other example embodiments for MV prediction, a coordination scheme can be used to implement general merge mode, MMVD, and some other types of MV prediction for both single reference mode and composite reference mode MV prediction. Various syntax elements can be used to signal the manner in which the MV for the current block is predicted.

[0173] For example, for a single reference mode, the following MV prediction modes may be signaled:

[0174] NEARMV - directly uses one of the motion vector predictors (MVPs) in the list indicated by the dynamic reference list (DRL) index without any MVD.

[0175] NEWMV - uses one of the motion vector predictors (MVPs) in the list signaled by the DRL index as a reference and applies the delta to the MVP (e.g., using MVD).

[0176] GLOBALMV - Uses motion vectors based on frame-level global motion parameters.

[0177] Likewise, for the compound reference inter prediction mode using two reference frames corresponding to the two MVs to be predicted, the following MV prediction modes may be signaled:

[0178] NEAR_NEARMV - For each of the two MVs to be predicted, without MVD, use one of the motion vector predictors (MVPs) in the list signaled by the DRL index.

[0179] NEAR_NEWMV - To predict the first of the two motion vectors, one of the motion vector predictors (MVPs) in the list signaled by the DRL index is used as a reference MV without MVD; to predict the second of the two motion vectors, one of the motion vector predictors (MVPs) in the list signaled by the DRL index is used as a reference MV, combined with an additionally signaled delta MV (MVD).

[0180] NEW_NEARMV - To predict the second of the two motion vectors, one of the motion vector predictors (MVPs) in the list signaled by the DRL index is used as a reference MV without MVD; to predict the first of the two motion vectors, one of the motion vector predictors (MVPs) in the list signaled by the DRL index is used as a reference MV in combination with an additionally signaled delta MV (MVD).

[0181] NEW_NEWMV - uses one of the motion vector predictors (MVPs) in the list signaled by the DRL index as a reference MV, and uses it in conjunction with the additionally signaled delta MV to predict each of the two MVs.

[0182] GLOBAL_GLOBALMV - Uses MVs from each reference based on their frame-level global motion parameters.

[0183] Therefore, the term "NEAR" above refers to MV prediction using a reference MV without MVD as a general merge mode, while the term "NEW" refers to MV prediction involving the use of a reference MV and offsetting it with a signaled MVD as in MMVD mode. For composite inter prediction, the reference base motion vector and motion vector delta above can generally be different or independent between the two references, even though they can be correlated, and this correlation can be exploited to reduce the amount of information required to signal the two motion vector deltas. In this case, joint signaling of the two MVDs can be implemented and indicated in the codestream.

[0184] The above dynamic reference list (DRL) can be used to store a set of indexed motion vectors that are dynamically maintained and considered as candidate motion vector predictors.

[0185] In some example embodiments, a predefined resolution of the MVD may be allowed. For example, a motion vector precision (or accuracy) of 1 / 8 pixel may be allowed. The MVD in the various MV prediction modes described above may be constructed and signaled in various ways. In some embodiments, various syntax elements may be used to signal the above one or more motion vector differences in reference frame list 0 or list 1.

[0186] For example, a syntax element called "mv_joint" may specify which components of the motion vector difference associated with it are non-zero. For MVD, this is signaled jointly for all non-zero components. For example, mv_joint has a value of

[0187] 0 may indicate that there is no non-zero MVD in the horizontal or vertical direction;

[0188] 1 may indicate that there is non-zero MVD only along the horizontal direction;

[0189] 2 may indicate that there is non-zero MVD only along the vertical direction;

[0190] 3 may indicate that there is non-zero MVD in both the horizontal and vertical directions.

[0191] When the "mv_joint" syntax element for MVD signals the absence of non-zero MVD components, no further MVD information is signaled. However, if the "mv_joint" syntax signals the presence of one or two non-zero components, additional syntax elements may be further signaled for each of the non-zero MVD components, as described below.

[0192] For example, a syntax element called "mv_sign" may be used to additionally specify whether the corresponding motion vector difference amount is positive or negative.

[0193] For another example, a syntax element called "mv_class" can be used to specify the class of the motion vector difference from a predefined set of classes for the corresponding non-zero MVD component. For example, the predefined classes for motion vector differences can be used to divide the continuous magnitude space of the motion vector differences into non-overlapping ranges, where each range corresponds to an MVD class. Thus, the signaled MVD class indicates the magnitude range of the corresponding MVD component. In the example implementation shown in Table 4 below, a higher class corresponds to a motion vector difference with a larger magnitude range. In Table 4, the notation (n,m] is used to represent a range of motion vector differences that is greater than n pixels and less than or equal to m pixels.

[0194] Table 4: Magnitude categories for motion vector differences

[0195] MV Category MVD value MV_CLASS_0 (0,2] MV_CLASS_1 (2,4] MV_CLASS_2 (4,8] MV_CLASS_3 (8,16] MV_CLASS_4 (16,32] MV_CLASS_5 (32,64] MV_CLASS_6 (64,128] MV_CLASS_7 (128,256] MV_CLASS_8 (256,512] MV_CLASS_9 (512,1024] MV_CLASS_10 (1024,2048]

[0196] In some other examples, a syntax element called "mv_bit" may be further used to specify the integer portion of the offset between a non-zero motion vector difference component and the starting magnitude of the correspondingly signaled MV class magnitude range. In this way, the mv_bit may indicate the magnitude or amplitude of the MVD. The number of bits required to signal the full range of each MVD class in "mv_bit" may vary as a function of the MV class. For example, MV_CLASS 0 and MV_CLASS 1 in the embodiment of Table 4 may require only a single bit to indicate an integer pixel offset of 1 or 2 from a starting MVD of 0; each higher MV_CLASS in the example embodiment of Table 4 may require one more bit for "mv_bit" than the previous MV_CLASS.

[0197] In some other examples, a syntax element called "mv_fr" may be further used to specify the first 2 fractional bits of the motion vector difference for the corresponding non-zero MVD component, while a syntax element called "mv_hp" may be used to specify the third fractional bit (high-resolution bit) of the motion vector difference for the corresponding non-zero MVD component. The 2-bit "mv_fr" essentially provides a 1 / 4 pixel MVD resolution, while the "mv_hp" bit may further provide a 1 / 8 pixel resolution. In some other embodiments, more than one "mv_hp" bit may be used to provide an MVD pixel resolution finer than 1 / 8 pixel. In some example embodiments, an additional flag may be signaled at one or more of the various levels to indicate whether an MVD resolution of 1 / 8 pixel or higher is supported. If an MVD resolution does not apply to a particular coding unit, the above syntax elements for the corresponding non-supported MVD resolution may not be signaled.

[0198] In some of the above example embodiments, fractional resolution may be independent of different categories of MVD. In other words, similar options for motion vector resolution may be provided using a predefined number of "mv_fr" and "mv_hp" bits for signaling the fractional MVD of non-zero MVD components, regardless of the magnitude of the motion vector difference.

[0199] However, in some other example embodiments, the resolution of motion vector differences in various MVD magnitude categories can be distinguished. Specifically, a high-resolution MVD for large MVD magnitudes of higher MVD categories may not provide a statistically significant improvement in compression efficiency. Thus, for a larger MVD magnitude range corresponding to a higher MVD magnitude category, the MVD can be encoded with a reduced resolution (integer pixel resolution or fractional pixel resolution). Similarly, typically for larger MVD values, the MVD can be encoded with a reduced resolution (integer pixel resolution or fractional pixel resolution). This MVD resolution that depends on the MVD category or on the MVD magnitude can generally be referred to as an adaptive MVD resolution, a magnitude-dependent adaptive MVD resolution, or a magnitude-dependent MVD resolution. The term "resolution" can further be referred to as "pixel resolution". The adaptive MVD resolution can be implemented in various ways as described in the following example embodiments to achieve overall better compression efficiency. In particular, due to the statistical observation that processing the MVD resolution of large-valued or high-category MVDs at a similar level to the resolution of low-valued or low-category MVDs in a non-adaptive manner may not significantly increase the coding efficiency of the inter-frame prediction residual for blocks with large-valued or high-category MVDs, the reduction in the number of signaling bits by targeting a less precise MVD may be greater than the additional bits required to encode the inter-frame prediction residual due to such less precise MVD. In other words, using a higher MVD resolution for large-valued or high-category MVDs may not yield more coding gain than using a lower MVD resolution.

[0200] In some general example embodiments, the pixel resolution or accuracy of the MVD may decrease or not increase as the MVD class increases. Decreasing the pixel resolution of the MVD corresponds to a coarser MVD (or a larger step size from one MVD class to the next). In some embodiments, the correspondence between MVD pixel resolution and MVD class may be specified, predefined, or preconfigured, and thus may not need to be signaled in the coded bitstream.

[0201] In some example embodiments, the MV categories of Table 3 may each be associated with a different MVD pixel resolution.

[0202] In some example embodiments, each MVD class may be associated with a single allowed resolution. In some other embodiments, one or more MVD classes may be associated with two or more selectable MVD pixel resolutions. Thus, the signal in the bitstream for a current MVD component having such an MVD class may be followed by additional signaling indicating the selectable pixel resolutions selected for the current MVD component.

[0203] In some example embodiments, the adaptively allowed MVD pixel resolutions may include, but are not limited to, 1 / 64-pel (pixel), 1 / 32 pixel, 1 / 16 pixel, 1 / 8 pixel, 1-4 pixel, 1 / 2 pixel, 1 pixel, 2 pixels, 4 pixels ... (in descending order of resolution). Thus, each ascending MVD class may be associated with one of these MVD pixel resolutions in a non-ascending manner. In some embodiments, an MVD class may be associated with two or more of the above resolutions, and the higher resolution may be lower than or equal to the lower resolution of the previous MVD class. For example, if MV_CLASS_3 of Table 4 is associated with optional 1 pixel and 2 pixel resolutions, then the highest resolution that MV_CLASS_4 of Table 4 can be associated with would be 2 pixels. In some other embodiments, the highest allowable resolution of an MV class may be higher than the lowest allowable resolution of the previous (lower) MV class. However, the average value of the allowed resolutions of an ascending MV class may only be non-ascending.

[0204] In some embodiments, when fractional pixel resolution higher than 1 / 8 pixel is allowed, the "mv_fr" and "mv_hp" signaling can be correspondingly extended to a total of more than 3 fractional bits.

[0205] In some example embodiments, fractional pixel resolution may only allow MVD classes that are lower than or equal to a threshold MVD class. For example, fractional pixel resolution may only allow MVD-CLASS 0 and not all other MV classes in Table 4. Similarly, fractional pixel resolution may only allow MVD classes that are lower than or equal to any of the other MV classes in Table 4. For other MVD classes that are higher than the threshold MVD class, only integer pixel resolutions of the MVD are allowed. In this way, fractional resolution signaling, such as one or more bits of the "mv-fr" and / or "mv-hp" bits, may not be required for MVD signaling that is signaled with MVD classes that are higher than or equal to the threshold MVD class. For MVD classes with resolutions lower than 1 pixel, the number of bits in the "mv-bit" signaling may be further reduced. For example, for MV_CLASS_5 in Table 4, the range of MVD pixel offsets is (32, 64], so 5 bits are required to signal the entire range at 1 pixel resolution. However, if MV_CLASS_5 is associated with 2-pixel MVD resolution (a lower resolution than 1 pixel resolution), then "mv_bit" may require 4 bits instead of 5 bits, and neither "mv-fr" nor "mv-hp" needs to be signaled after the signaling of "mv_class" as MV-CLASS_5.

[0206] In some example embodiments, fractional pixel resolution may only allow MVDs with integer values ​​below a threshold integer pixel value. For example, fractional pixel resolution may only allow MVDs with less than 5 pixels. Corresponding to this example, fractional resolution may allow MV_CLASS_0 and MV_CLASS_1 of Table 4, and disallow all other MV classes. For another example, fractional pixel resolution may only allow MVDs with less than 7 pixels. Corresponding to this example, fractional resolution may allow MV_CLASS_0 and MV_CLASS_1 of Table 4 (range below 5 pixels), and disallow MV_CLASS_3 and higher (range above 5 pixels). For MVDs belonging to MV_CLASS_2, whose pixel range contains 5 pixels, fractional pixel resolution of the MVD may or may not be allowed depending on the "mv-bit" value. If the signaled "m-bit" value is 1 or 2 (such that the integer part of the signaled MVD is 5 or 6, calculated as the start of the pixel range of MV_CLASS_2 with an offset of 1 or 2 indicated by "m-bit"), then fractional pixel resolution may be allowed. Otherwise, if the signaled "mv-bit" value is 3 or 4 (such that the integer part of the signaled MVD is 7 or 8), then fractional pixel resolution may not be allowed.

[0207] In some other embodiments, only a single MVD value may be allowed for MV classes that are equal to or above a threshold MV class. For example, such a threshold MV class may be MV_CLASS2. Thus, MV_CLASS_2 and above may only allow for a single MVD value and no fractional pixel resolution. The single allowed MVD values ​​for these MV classes may be predefined. In some examples, the allowed single value may be a higher end value for the corresponding ranges for these MV classes in Table 4. For example, MV_CLASS_2 through MV_CLASS_10 may be threshold classes that are higher than or equal to MV_CLASS2, and the single allowed MVD values ​​for these classes may be predefined as 8, 16, 32, 64, 128, 256, 512, 1024, and 2048, respectively. In some other examples, the allowed single value may be a middle value for the corresponding ranges for these MV classes in Table 4. For example, MV_CLASS_2 to MV_CLASS_10 may be above the class threshold, and the single allowed MVD values ​​for these classes may be predefined as 3, 6, 12, 24, 48, 96, 192, 384, 768, and 1536, respectively. Any other value within the range may also be defined as the single allowed resolution for the corresponding MVD class.

[0208] In the above embodiment, when the signaled "mv_class" is equal to or above the predefined MVD category threshold, only "mv_class" signaling is sufficient to determine the MVD value. "mv_class" and "mv_sign" will then be used to determine the magnitude and direction of the MVD.

[0209] In this way, when MVD is signaled for only one reference frame (from reference frame list 0 or list 1, but not both), or when MVD is signaled for two reference frames together, the accuracy (or resolution) of the MVD can depend on the associated category of the motion vector difference and / or the magnitude of the MVD in Table 3.

[0210] In some other embodiments, the pixel resolution or accuracy of the MVD may decrease or not increase as the MVD magnitude increases. For example, the pixel resolution may depend on the integer portion of the MVD magnitude. In some embodiments, the fractional pixel resolution may only allow MVD magnitudes that are less than or equal to an amplitude threshold. For a decoder, the integer portion of the MVD magnitude may first be extracted from the bitstream. The pixel resolution may then be determined, and a decision may then be made as to whether any fractional MVDs are present in the bitstream and need to be parsed (e.g., if the fractional pixel resolution does not allow for a particular extracted MVD integer magnitude, then the fractional MVD bits may not be included in the bitstream that needs to be extracted). The above example embodiments relating to adaptive MVD pixel resolution depending on MVD category are applicable to adaptive MVD pixel resolution depending on MVD magnitude. For a specific example, an MVD category above or including a magnitude threshold may be allowed to have only one predefined value.

[0211] As described in detail above, for the composite reference inter prediction mode, the current coding block can be predicted by two or more reference blocks. Each reference block can be associated with a reference frame (unidirectionally or bidirectionally relative to the current frame associated with the current coding block). Each reference block can be associated with a motion vector relative to the current coding block. The motion vectors of the reference blocks used for the current coding block can generally be different (although in some cases they can be the same). As described above, each of these motion vectors can be predicted by a reference motion vector selected from the candidate motion vectors in, for example, a DRL in combination with the corresponding MVD.

[0212] In some embodiments, to predict any two or more motion vectors associated with two or more reference blocks corresponding to the current coding block, a single MVD (instead of two or more MVDs) can be jointly signaled, and the actual two or more MVDs associated with the two or more predicted motion vectors can be derived from the signed MVD. In other words, for the encoder, two or more reference blocks corresponding to two or more reference frames can first be identified for use in predicting the current coding block in the current frame. The corresponding two or more motion vectors of the two or more reference blocks can be determined by the encoder. A predictor / reference motion vector for predicting the two or more motion vectors can be selected from the DRL (for example, the predictor / reference motion vector can be identified as the motion vector that is most similar to the at least two motion vectors to be predicted). In some other embodiments, two or more predictors / reference motion vectors can be identified (in other words, different motion vectors can be associated with different candidate predictors / reference motion vectors in the DRL). The encoder can then obtain two or more MVDs corresponding to the two or more motion vectors by taking the difference between the two or more motion vectors to be predicted and the corresponding prediction value / one or more reference motion vectors (a common prediction value / reference motion vector or a separate prediction value / reference motion vector). In some example embodiments, the two or more MVDs can be jointly encoded into one MVD in various ways, and have information items that can be used to decode the jointly encoded MVD so that each of the two or more MVDs can be derived at the decoder. In some embodiments, given a single reference frame, another reference frame can be derived based on the given reference frame and the current frame.

[0213] Correspondingly, the decoder can first extract the jointly encoded MVD and other information items from the codestream. The decoder can then derive individual MVDSs for two or more MVDSs based on the jointly encoded / signaled MVD and other information items. The decoder can then derive two or more motion vectors based on the derived individual MVDs and a single predictor / reference motion vector or a separate predictor / reference motion vector from the DRL signaled in the codestream.

[0214] Some implementations of signaling motion vector differences may have some issues / problems. For example, for NEW_NEARMV mode and NEAR_NEWMV, one delta MV needs to be signaled for the first / second MV, and no delta MV needs to be signaled or derived for the other MV; and therefore, the correlation of the motion vector differences in the two reference lists may not be fully utilized.

[0215] Figure 18A flowchart 1800 of an example method according to the principles of the above embodiments for signaling an MVD is shown. The example decoding method flow begins at 1801 and may include some or all of the following steps: at S1810, receiving an encoded video stream; at S1820, obtaining a first motion vector difference (MVD) and a dynamic reference list (DRL) index for a current video block from the encoded video stream; at S1830, deriving a second MVD for the current video block based on the first MVD; at S1840, generating, by a device, a motion vector (MV) pair based on the first MVD, the derived second MVD, and a motion vector predictor (MVP) indicated by the DRL index; and at S1850, decoding, by the device, the current video block based on the MV pair. The example method stops at S1899.

[0216] In some embodiments, two reference frames can be used in a composite reference mode. When the POCs of the two reference frames for a motion vector pair are greater than or less than the POC of the current frame, the directions of the two reference frames can be considered the same. Otherwise, when the POC of one reference frame is greater than the POC of the current frame and the POC of the other reference frame is less than the POC of the current frame, the directions of the two reference frames can be considered different.

[0217] In some embodiments, the current video block is in a composite reference mode with two reference frames; the composite reference mode includes NEW_NEAR mode or NEAR_NEW mode. For non-limiting example, in NEW_NEAR (or NEAR_NEW) mode, an MVD, also called a delta MV, for a first (or second) MV named delta_mv_1 can be used to derive a delta MV for a second (or first) MV named delta_mv_2. Thereafter, delta_mv_1 and delta_mv_2 are added to a motion vector predictor (MVP) indicated by a DRL index to generate an MV pair for a block, where only one of the delta MVs is signaled and transmitted to the decoder.

[0218] In some embodiments, Figure 18 The method may further include obtaining, by the device, a flag for the current video block from the coded video stream, wherein: in response to the current video block being in a composite reference mode of NEW_NEAR mode, the flag indicates whether to add the second MVD to the MVP in the second list indicated by the DRL index, and / or in response to the current video block being in a composite reference mode of NEAR_NEW mode, the flag indicates whether to add the first MVD to the MVP in the first list indicated by the DRL index.

[0219] In various embodiments or implementations of the present disclosure, the flag may be referred to as syntax or syntax element; and / or a motion vector (MV) may be derived based on MVP and MVD, e.g., MV=MVP+MVD; and / or an MV pair includes two motion vectors corresponding to two reference frames.

[0220] For a non-limiting example, if the current block is in NEW_NEAR (or NEAR_NEW) mode, an additional flag named mirrored_mvd_flag may be signaled to indicate whether delta_mv_2 (or delta_mv_1) is derived from delta_mv_1 (or delta_mv_2) and added to the MVP in the second (or first) reference list indicated by the DRL index.

[0221] In some embodiments, Figure 18 The method may further include obtaining, by the device, a flag for the current video block from the coded video stream in response to a condition of the current video block being met, wherein: in response to the current video block being in a composite reference mode of NEW_NEAR mode, the flag indicates whether to add the second MVD to the MVP in the second list indicated by the DRL index, and / or in response to the current video block being in a composite reference mode of NEAR_NEW mode, the flag indicates whether to add the first MVD to the MVP in the first list indicated by the DRL index.

[0222] For a non-limiting example, if the current block is in NEW_NEAR (or NEAR_NEW) mode, an additional flag named mirrored_mvd_flag may be conditionally signaled based on the motion information of the current block to indicate whether delta_mv_2 (or delta_mv_1) is derived from delta_mv_1 (or delta_mv_2) and added to the MVP in the second (or first) reference list indicated by the DRL index.

[0223] In some embodiments, the condition of the current video block includes a picture order count (POC) of the current frame being between the POCs of two reference frames of the current video block.

[0224] For a non-limiting example, if the current block is in NEW_NEAR (or NEAR_NEW) mode, the POC of one reference frame is greater than the current frame, and the POC of the other reference frame is less than the current frame, an additional flag named mirrored_mvd_flag may be signaled to indicate whether delta_mv_2 (or delta_mv_1) is derived from delta_mv_1 (or delta_mv_2) and added to the MVP in the second (or first) reference list indicated by the DRL index.

[0225] In some embodiments, the condition of the current video block includes a first POC distance between the current frame and the first reference frame being equal to a second POC distance between the current frame and the second reference frame.

[0226] For non-limiting examples, when the current block has two reference frames and the temporal distance (or POC distance) between the current frame and the two reference frames is the same, the mirrored_mvd_flag may be signaled. Otherwise, when the current block has two reference frames and the temporal distances between the current frame and the two reference frames are different, the mirrored_mvd_flag is not signaled but derived as 0, which in some embodiments indicates that only one MVD is applied to one of the two motion vectors.

[0227] In some embodiments, in response to a condition of the current video block being satisfied: in response to the current video block being in a composite reference mode of NEW_NEAR mode, adding the second MVD to the MVP in the second list indicated by the DRL index, and / or in response to the current video block being in a composite reference mode of NEAR_NEW mode, adding the first MVD to the MVP in the first list indicated by the DRL index.

[0228] For a non-limiting example, when the current block is in NEW_NEAR (or NEAR_NEW) mode, delta_mv_2 (or delta_mv_1) can be derived from delta_mv_1 (or delta_mv_2) based on the motion information in the two reference lists for the current block, and the derived delta_mv_2 (or delta_mv_1) is added to the MVP in the second (or first) reference list indicated by the DRL index.

[0229] In some embodiments, the condition of the current video block includes a picture order count (POC) of the current frame being between the POCs of two reference frames for the current video block.

[0230] For a non-limiting example, when the POC of one reference frame is greater than the current frame and the POC of another reference frame is less than the current frame, delta_mv_2 (or delta_mv_1) can be derived from delta_mv_1 (or delta_mv_2) and the derived delta_mv_2 (or delta_mv_1) can be added to the MVP in the second (or first) reference list indicated by the DRL index.

[0231] In some embodiments, the condition of the current video block includes a first POC distance between the current frame and the first reference frame being equal to a second POC distance between the current frame and the second reference frame.

[0232] For a non-limiting example, when the POC of one reference frame is greater than the current frame, the POC of another reference frame is less than the current frame, and the POC distances of the two reference frames to the current frame are equal, delta_mv_2 (or delta_mv_1) can be derived from delta_mv_1 (or delta_mv_2), and the derived delta_mv_2 (or delta_mv_1) can be added to the MVP in the second (or first) reference list indicated by the DRL index.

[0233] In the embodiments and implementations of the present disclosure, any steps and / or operations can be combined or arranged in any number or order as needed. Two or more steps and / or operations can be performed in parallel. The embodiments and implementations in the present disclosure can be used alone or in combination in any order. Furthermore, each of the method (or embodiment), encoder and decoder can be implemented by a processing circuit (for example, one or more processors or one or more integrated circuits). In one example, one or more processors execute a program stored in a non-volatile computer-readable medium. The embodiments in the present disclosure can be applied to luminance blocks or chrominance blocks. The term "block" can be interpreted as a prediction block, a coding block or a coding unit (i.e., CU). The term "block" can also be used here to refer to a transform block. In the following items, when talking about block size, it can refer to block width or height, or the maximum value of width and height, or the minimum value of width and height, or the area size (width*height), or the aspect ratio of the block (width:height, or height:width).

[0234] The techniques described above may be implemented as computer software using computer-readable instructions and physically stored in one or more computer-readable media. Figure 19 A computer system (1900) suitable for implementing certain embodiments of the disclosed subject matter is shown.

[0235] The 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 or through interpretation, microcode execution, or the like by one or more computer central processing units (CPUs), graphics processing units (GPUs), or the like.

[0236] The instructions may be executed on various types of computers or computer components, including, for example, personal computers, tablets, servers, smart phones, gaming devices, Internet of Things devices, and the like.

[0237] Figure 19The components shown for the computer system (1900) are exemplary in nature and are not intended to suggest any limitation on the scope of use or functionality of the computer software implementing the embodiments of the application. Nor should the configuration of components be interpreted as having any dependency or requirement on any one or combination of components shown in the exemplary embodiment of the computer system (1900).

[0238] The computer system (1900) may include certain human interface input devices. Such human interface input devices may be responsive to input from one or more human users through, for example, tactile input (e.g., keystrokes, swipes, data glove movements), audio input (e.g., voice, taps), visual input (e.g., gestures), and olfactory input (not depicted). The human interface devices may also be used to capture certain media that may not be directly associated with conscious human input, such as audio (e.g., speech, music, ambient sounds), images (e.g., scanned images, photographic images obtained from a still image camera), and video (e.g., two-dimensional video, three-dimensional video including stereoscopic video).

[0239] Input human interface devices may include one or more of the following (only one of each is depicted): keyboard (1901), mouse (1902), trackpad (1903), touch screen (1910), data gloves (not shown), joystick (1905), microphone (1906), scanner (1907), camera (1908).

[0240] The computer system (1900) may also include certain human interface output devices. Such human interface output devices may stimulate the senses of one or more human users through, for example, tactile output, sound, light, and smell / taste. Such human interface output devices may include tactile output devices (e.g., tactile feedback from a touch screen (1910), a data glove (not shown), or a joystick (1905), although there may also be tactile feedback devices that do not function as input devices), audio output devices (e.g., speakers (1909), headphones (not depicted)), visual output devices (e.g., screens (1910), including cathode ray tube (CRT) screens, liquid crystal display (LCD) screens, plasma screens, organic light emitting diode (OLED) screens, each with or without touch screen input capabilities, each with or without tactile feedback capabilities—some of which are capable of outputting two-dimensional visual output or output greater than three dimensions through, for example, stereographic output; virtual reality glasses (not depicted), holographic displays, and smoke boxes (not depicted), and printers (not depicted).

[0241] The computer system (1900) may also include human-accessible storage devices and associated media for the storage devices, such as optical media including CD / DVD ROM / RW (1920) with CD / DVD etc. media (1921), thumb drives (1922), removable hard drives or solid-state drives (1923), older magnetic media such as tapes and floppy disks (not depicted), specialized devices based on ROM / application specific integrated circuits (ASICs) / programmable logic devices (PLDs), such as security devices (not depicted), and the like.

[0242] Those skilled in the art will also understand that the term "computer-readable medium" used in connection with the presently disclosed subject matter does not encompass transmission media, carrier waves, or other transient signals.

[0243] The computer system (1900) may also include an interface (1954) to one or more communication networks (1955). The network may be, for example, wireless, wired, or optical. The network may also be local, wide-area, metropolitan, vehicular and industrial, real-time, delay-tolerant, and the like. Examples of networks include local area networks such as Ethernet, wireless LAN, cellular networks including Global System for Mobile Communications (GSM), third generation (3G), fourth generation (4G), fifth generation (5G), long term evolution (LTE), etc., TV wired or wireless wide area digital networks including cable TV, satellite TV, and terrestrial broadcast TV, vehicular networks including controller area network bus (CANBus), and industrial networks, and the like. Some networks typically require an external network interface adapter attached to some general data port or peripheral bus (1949) (e.g., a universal serial bus (USB) port of the computer system (1900)); other networks are typically integrated into the core of the computer system (1900) by attaching to a system bus as described below (e.g., integrated into a PC computer system through an Ethernet interface, or integrated into a smartphone computer system through a cellular network interface). Using any of these networks, the computer system (1900) can communicate with other entities. Such communication can be one-way receive only (e.g., broadcast TV), one-way send only (e.g., CANBus connected to some CANBus devices), or bidirectional, for example, using a local area digital network or a wide area digital network to connect to other computer systems. Certain protocols and protocol stacks can be used on each of those networks and network interfaces as described above.

[0244] The above-mentioned human interface device, human-accessible storage device, and network interface may be attached to the core (1940) of the computer system (1900).

[0245] The core (1940) may include one or more central processing units (CPUs) (1941), graphics processing units (GPUs) (1942), specialized programmable processing units in the form of field programmable gate areas (FPGAs) (1943), hardware accelerators for certain tasks (1944), a graphics adapter (1950), and the like. These devices, along with read-only memory (ROM) (1945), random access memory (1946), and internal mass storage devices (1947) such as internal non-user accessible hard drives and solid-state drives (SSDs), may be connected via a system bus (1948). In some computer systems, the system bus (1948) may be accessible via one or more physical plugs to enable expansion with additional CPUs, GPUs, and the like. Peripheral devices may be attached to the core's system bus (1948) directly or via a peripheral bus (1949). In one example, a screen (1910) may be connected to a graphics adapter (1950). Architectures for peripheral buses include peripheral component interconnect (PCI), USB, and the like.

[0246] The CPU (1941), GPU (1942), FPGA (1943), and accelerator (1944) can execute certain instructions, which, when combined, constitute the aforementioned computer code. The computer code can be stored in ROM (1945) or RAM (1946). Transient data can also be stored in RAM (1946), while permanent data can be stored, for example, in an internal mass storage device (1947). Fast storage and retrieval of any of the memory devices can be achieved by using a cache memory, which can be closely associated with one or more of the CPU (1941), GPU (1942), mass storage device (1947), ROM (1945), RAM (1946), etc.

[0247] The computer readable medium may have computer codes for executing various computer-implemented operations. The media and computer codes may be those designed and constructed specifically for the purposes of this application, or they may be of a type well known and available to those skilled in the art of computer software.

[0248] As a non-limiting example, a computer system having the architecture (1900) and, in particular, the core (1940) can provide functionality resulting from the execution of software embodied in one or more tangible computer-readable media by a processor (including a CPU, GPU, FPGA, accelerator, etc.). Such computer-readable media can be media associated with the user-accessible mass storage devices described above and certain non-transitory storage devices of the core (1940) (e.g., the core internal mass storage device (1947) or ROM (1945)). Software implementing various embodiments of the present application can be stored in such devices and executed by the core (1940). Depending on specific needs, the computer-readable medium may include one or more memory devices or chips. The software can enable the core (1940), and specifically, the processors therein (including CPU, GPU, FPGA, etc.), to perform specific processes or specific portions of specific processes described herein, including defining data structures stored in RAM (1946) and modifying such data structures according to processes defined by the software. Additionally or alternatively, the computer system may provide functionality produced by logic hardwired or otherwise embodied in circuitry (e.g., accelerator (1944)), which may operate in place of or in conjunction with software to perform specific processes or specific portions of specific processes described herein. Where appropriate, references to software may encompass logic, and vice versa. Where appropriate, references to computer-readable media may encompass circuitry (e.g., integrated circuits (ICs)) storing software for execution, circuitry embodying logic for execution, or both. This application encompasses any suitable combination of hardware and software.

[0249] Although this application describes several exemplary embodiments, various modifications, permutations, combinations, and substitutions are possible within the scope of this application. Therefore, it should be understood that within the spirit and scope of this application, those skilled in the art will be able to design various systems and methods that, although not explicitly shown or described herein, embody the principles of this application.

[0250] Appendix A: Acronyms

[0251] JEM: Joint Exploration Model

[0252] VVC: Versatile Video Coding

[0253] BMS: Benchmark Set, benchmark set

[0254] MV: Motion Vector

[0255] HEVC: High Efficiency Video Coding

[0256] SEI: Supplementary Enhancement Information, auxiliary enhancement information

[0257] VUI: Video Usability Information, video availability information

[0258] GOP: Groups of Pictures, picture groups

[0259] TU: Transform Unit

[0260] PU: Prediction Unit

[0261] CTU: Coding Tree Unit, coding tree unit

[0262] CTB: Coding Tree Block, coding tree block

[0263] PB: Prediction Block

[0264] HRD: Hypothetical Reference Decoder, hypothetical reference decoder

[0265] SNR: Signal Noise Ratio

[0266] CPU: Central Processing Unit

[0267] GPU: Graphics Processing Unit

[0268] CRT: Cathode Ray Tube

[0269] LCD: Liquid-Crystal Display

[0270] OLED: Organic Light-Emitting Diode

[0271] CD: Compact Disc

[0272] DVD: Digital Video Disc

[0273] ROM: Read-Only Memory

[0274] RAM: Random Access Memory

[0275] ASIC: Application-Specific Integrated Circuit

[0276] PLD: Programmable Logic Device

[0277] LAN: Local Area Network

[0278] GSM: Global System for Mobile communications

[0279] LTE: Long-Term Evolution CANBus: Controller Area Network Bus

[0280] USB: Universal Serial Bus

[0281] PCI: Peripheral Component Interconnect, peripheral device interconnect

[0282] FPGA: Field Programmable Gate Array

[0283] SSD: Solid-state drive

[0284] IC: Integrated Circuit

[0285] HDR: high dynamic range

[0286] SDR: standard dynamic range

[0287] JVET stands for Joint Video Exploration Team.

[0288] MPM: most probable mode

[0289] WAIP: Wide-Angle Intra Prediction, wide-angle intra prediction

[0290] CU: Coding Unit

[0291] PU: Prediction Unit

[0292] TU: Transform Unit

[0293] CTU: Coding Tree Unit, coding tree unit

[0294] PDPC: Position Dependent Prediction Combination, position-determined intra-frame prediction combination ISP: Intra Sub-Partitions, intra-frame sub-partitions

[0295] SPS: Sequence Parameter Setting, sequence parameter setting

[0296] PPS: Picture Parameter Set, picture parameter set

[0297] APS: Adaptation Parameter Set

[0298] VPS: Video Parameter Set, video parameter set

[0299] DPS: Decoding Parameter Set, decoding parameter set

[0300] ALF: Adaptive Loop Filter, adaptive loop filter

[0301] SAO: Sample Adaptive Offset, sample adaptive offset CC-ALF: Cross-Component Adaptive Loop Filter, cross-component adaptive loop filter CDEF: Constrained Directional Enhancement Filter, constrained directional enhancement filter CCSO: Cross-Component Sample Offset, cross-component sample offset

[0302] LSO: Local Sample Offset, local sample offset

[0303] LR: Loop Restoration Filter, loop restoration filter

[0304] AV1: AOMedia Video 1, Alliance for Open Media Video 1

[0305] AV2: AOMedia Video 2, Alliance for Open Media Video 2

[0306] MVD: Motion Vector difference, motion vector difference

[0307] CfL: Chroma from Luma, predicting chromaticity based on brightness

[0308] SDT: Semi Decoupled Tree

[0309] SDP: Semi Decoupled Partitioning, semi-decoupled partitioning

[0310] SST: Semi Separate Tree

[0311] SB: Super Block, IBC (or IntraBC): Intra Block Copy, intra-frame block copy

[0312] CDF: Cumulative Density Function, cumulative density function

[0313] SCC: Screen Content Coding, screen content coding

[0314] GBI: Generalized Bi-prediction, generalized bidirectional prediction

[0315] BCW: Bi-prediction with CU-level Weights, bidirectional prediction with CU-level weights

[0316] CIIP: Combined intra-inter prediction, intra-frame and inter-frame joint prediction

[0317] POC: Picture Order Count, picture order count

[0318] RPS stands for Reference Picture Set.

[0319] DPB: Decoded Picture Buffer, decoded picture buffer

[0320] MMVD: Merge Mode with Motion Vector Difference, MV: Motion Vector, Motion Vector

[0321] MVP: Motion Vector Predictor Motion Vector Predictor, motion vector predictor

Claims

1. A video decoding method, characterized in that: include: Receive encoded video stream; determining whether to apply the NEW_NEAR mode or the NEAR_NEW mode to a current video block of the encoded video stream; When it is determined that the NEW_NEAR mode is applied to the current video block, determining a first flag in the coded video stream, wherein the first flag indicates whether to derive a second motion vector difference (MVD) from the first MVD and add the second MVD to a motion vector predictor (MVP) in a second list indicated by a dynamic reference list (DRL) index; When it is determined that the NEAR_NEW mode is applied to the current video block, determining a first flag in the coded video stream, wherein the first flag indicates whether to derive a first MVD from a second MVD and add the first MVD to the MVP in the first list indicated by the DRL index; generating a motion vector (MV) pair including a first MV generated by adding a first MVD to the MVPs in the first list and a second MV generated by adding a second MVD to the MVPs in the second list; and The current video block is decoded using the MV pair.

2. The method according to claim 1, characterized in that The first flag is conditionally signaled based on motion information of a current video block.

3. The method according to claim 2, wherein: The motion information includes a picture order count (POC) of a current frame between POCs of two reference frames of the current video block.

4. The method according to claim 2, wherein: The motion information includes a first POC distance between the current frame and a first reference frame being equal to a second POC distance between the current frame and a second reference frame.

5. A video encoding method, applied to an encoder including a local decoder, characterized in that: include: Receive encoded video stream; determining whether to apply the NEW_NEAR mode or the NEAR_NEW mode to a current video block of the encoded video stream; When it is determined that the NEW_NEAR mode or the NEAR_NEW mode is applied to the current video block, determining a first flag in the coded video stream, wherein the first flag indicates whether to derive a second motion vector difference (MVD) from the first MVD and add the second MVD to a motion vector predictor (MVP) in a second list indicated by a dynamic reference list (DRL) index; When it is determined that the NEAR_NEW mode is applied to the current video block, determining a first flag in the coded video stream, wherein the first flag indicates whether to derive a first MVD from a second MVD and add the first MVD to the MVP in the first list indicated by the DRL index; generating a motion vector (MV) pair including a first MV generated by adding a first MVD to the MVPs in the first list and a second MV generated by adding a second MVD to the MVPs in the second list; and The current video block is decoded using the MV pair.

6. A video decoding device, characterized in that: The device comprises: a memory for storing instructions; and A processor in communication with the memory, wherein when the processor executes the instructions, the processor is configured to cause the apparatus to perform the method according to any one of claims 1 to 5.

7. A video encoding device, characterized in that: The device comprises: a memory for storing instructions; and A processor in communication with the memory, wherein when the processor executes the instructions, the processor is configured to cause the apparatus to perform the method of claim 6.

8. A non-volatile computer-readable storage medium storing instructions, characterized in that: When the instructions are executed by a processor, the instructions are configured to cause the processor to perform the method according to any one of claims 1 to 5.

9. An electronic device, characterized in that: The invention comprises a memory for storing computer-readable instructions; a processor for reading the computer-readable instructions and executing the method according to any one of claims 1 to 5 according to the instructions of the computer-readable instructions.

10. A method for storing a video stream, characterized in that: Execute the method of claim 5 to generate a video stream, and store the video stream.

11. A method for transmitting a video stream, characterized in that: Execute the method according to claim 5 to generate a video stream, and transmit the video stream.

12. A computer-readable storage medium storing a computer program / instruction and a video stream, characterized in that: When the computer program / instruction is executed by a processor, the steps of the method according to claim 5 are implemented to generate the video code stream.

Images