CN112333450B - Video coding and decoding method and device - Google Patents

Abstract

The application discloses a video decoding method and device. The method comprises the following steps: decoding coding and decoding information of a current block from an encoded video bit stream, wherein the coding and decoding information indicates the current block to be coded and decoded by using an interframe combination mode; pruning a merge candidate list including at least one Control Point Motion Vector Prediction (CPMVP) for the current block, the pruning being based on motion information associated with each of the at least one CPMVP merge candidates and a flag indicating whether the respective neighboring block uses an optional half-pixel (half-Pel) Interpolation Filter (IF); reconstructing samples in the current block based on one CPMVP merge candidate of the at least one CPMVP merge candidates.

Description

Video coding and decoding method and device

The present application claims priority to U.S. provisional application No. 62/883,084, filed 8/5/2019, "method for adaptive motion vector resolution (Methods on adaptive Motion Vector Resolution)", and U.S. application No. 16/941,286, filed 7/28/2020, which are incorporated herein by reference in their entirety.

Technical Field

Embodiments of the present disclosure relate to the field of video encoding and decoding.

Background

The background description provided herein is for the purpose of presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present application.

Currently, video encoding and decoding may be performed using inter-image prediction in combination with motion compensation. Uncompressed digital video typically includes a series of images. For example, each image has luma samples of 1920×1080 resolution and associated chroma samples. The series of images may have, for example, 60 images per second or a fixed or variable image rate (also referred to as frame rate) of 60 Hz. Thus, uncompressed video has significant bit rate requirements. For example, 1080p60:2:0 video (1920 x 1080 luma sample resolution at 60Hz frame rate) of 8 bits per sample requires a bandwidth of approximately 1.5 Gbit/s. Such video, one hour in length, requires over 600GB of memory space.

One purpose of video encoding and decoding may be to reduce redundancy in an input video signal by compression. Compression helps reduce the bandwidth or storage space requirements described above, which in some cases may be reduced by two orders of magnitude or more. Typically, lossless compression and lossy compression, as well as combinations thereof, may be used. Lossless compression refers to a technique by which an exact copy of the original signal can be reconstructed from the compressed original signal. When lossy compression is used, the reconstructed signal may be different from the original signal, but the distortion between the original signal and the reconstructed signal is small, so that the reconstructed signal can achieve the desired use. Lossy compression is widely used in the video field. The amount of distortion that is tolerated varies from application to application. For example, users of consumer live applications can tolerate higher distortion than users of television programming applications. The achievable compression ratio may reflect: the higher the allowable/tolerable distortion, the higher the compression ratio that can be produced.

Motion compensation may be a lossy compression technique and may be associated with the following techniques: for blocks of sample data from a previously reconstructed image or a part thereof (reference image), after a spatial shift in the direction indicated by the Motion Vector (MV) can be used to predict a newly reconstructed image or a part of an image. In some cases, the reference image may be the same as the image currently being reconstructed. Each MV may have two dimensions X and Y, or three dimensions, the third dimension indicating the reference image being used (indirectly, the third dimension may also be the temporal dimension).

In some video compression techniques, MVs that are applicable to a certain sample data region may be predicted from other MVs, e.g., relating to another sample data region spatially adjacent to the region being reconstructed, and the decoding order is before the MVs of the certain sample data region. In this way, the amount of data required to encode the MVs can be greatly reduced, thereby eliminating redundancy and improving compression. For example, when encoding an input video signal from a camera (referred to as raw video), there is the following statistical likelihood: multiple regions that are larger than a single MV region will move in similar directions, and thus, in some cases, prediction can be performed using similar motion vectors extracted from MVs of neighboring regions, and thus, MV prediction is very efficient. In this way, MVs determined for a given region are made similar or identical to MVs predicted from surrounding MVs, and after entropy encoding, the number of bits representing MVs is smaller than that used in the case of directly encoding MVs. In some cases, MV prediction may be an embodiment of lossless compression of a signal (i.e., MV) extracted from an original signal (i.e., a sample stream). In other cases, MV prediction itself may be lossy, for example, due to rounding errors when calculating the prediction value from several surrounding MVs.

Various MV prediction mechanisms are described in h.265/HEVC (ITU-T h.265 recommendation, "high efficiency video codec (High Efficiency Video Coding)", month 12 in 2016). Among the various MV prediction mechanisms provided by h.265, described herein is a technique hereinafter referred to as "spatial merging".

Referring to fig. 1, a current block (101) includes samples that have been found by an encoder during a motion search process, which may be predicted from a previous block of the same size that has generated a spatial offset. In addition, rather than encoding the MVs directly, the MVs may be derived from metadata associated with one or more reference pictures. For example, using the MVs associated with any of the five surrounding samples A0, A1 and B0, B1, B2 (102 to 106, respectively), the MVs are derived (in decoding order) from the metadata of the nearest reference picture. In h.265, MV prediction may use the prediction value of the same reference picture that neighboring blocks are also using.

Disclosure of Invention

Aspects of the present disclosure provide methods and apparatus for video encoding/decoding. In some examples, an apparatus for video decoding includes a processing circuit. The processing circuitry may be operative to decode the codec information for the current block from the encoded video bitstream. The codec information may indicate an inter merge mode of the current block. The processing circuitry may prune a merge candidate list including at least one CPMVP merge candidate for the current block, the pruning may be based on motion information and flags associated with each of the at least one CPMVP merge candidates. Each CPMVP combining candidate of the at least one CPMVP combining candidates may be information of each neighboring block of the current block. The flag may indicate whether an optional half-pixel (half-Pel) interpolation filter (interpolation filter, IF) is used for the respective neighboring block. The processing circuitry may reconstruct samples in the current block based on one of the at least one CPMVP merge candidates.

In one embodiment, the at least one CPMVP merge candidate includes a first candidate CPMVP and a second candidate CPMVP. The first candidate CPMVP may include first motion information of a first neighboring block and a first flag. The second candidate CPMVP may include second motion information and a second flag of a second neighboring block. The first neighboring block and the second neighboring block may be neighboring blocks of the current block. The first flag and the second flag may indicate whether the respective first neighboring block and second neighboring block use an optional half-Pel IF. The processing circuit may prune the merge candidate list based on the first motion information, the second motion information, the first flag, and the second flag.

In one embodiment, the motion information includes motion vectors of neighboring blocks of the current block and corresponding reference images.

Aspects of the present disclosure provide methods and apparatus for video encoding/decoding. In some examples, an apparatus for video decoding includes a processing circuit. The processing circuitry may be operative to decode codec information for a current block in a current picture from the encoded video bitstream. The codec information may include a flag indicating whether a half-Pel (half-Pel) precision is used for a component of a Motion Vector Difference (MVD) of the current block. The processing circuit may determine the value of the flag based on one of: (i) at least one of the first flag and the second flag; (ii) A temporal layer Identification (ID) of a current image in the temporal layer; and (iii) block size information for the current block. The first flag may indicate whether the left neighboring block of the current block uses an optional half-Pel IF, and the second flag may indicate whether the upper neighboring block of the current block uses an optional half-Pel IF. In response to the value of the flag indicating that the component of the MVD uses half-Pel precision, the processing circuit may determine a Motion Vector (MV) for the current block using half-Pel precision and reconstruct samples in the current block based on the MV.

In one example, the processing circuit may determine one context model from a plurality of context models in context-adaptive binary arithmetic coding (CABAC) based on at least one of the first flag and the second flag. The processing circuit may determine the value of the flag using CABAC with the determined context model.

In one example, the processing circuit may determine whether to use the context model in CABAC based on at least one of the first flag and the second flag. In response to determining to use the context model, the processing circuitry may determine the value of the flag using CABAC with the context model. In response to determining not to use the context model, the processing circuitry may use the bypass codec mode to determine a value of the flag.

In one example, the processing circuit may determine a context model to use in CABAC based on a temporal layer ID of the current image. The processing circuit may determine the value of the flag using CABAC with the determined context model.

The context model is one of one or more context models in CABAC. The temporal layer ID is one of one or more temporal layer IDs of a corresponding one or more temporal layers allowed by the current image. The temporal layer ID corresponds to the determined context model.

In one example, the processing circuit may determine the context model from two context models in CABAC based on the temporal layer ID and a threshold.

In one example, the processing circuit may determine the context model from N context models in CABAC based on the temporal layer ID and the (N-1) thresholds. N is less than the allowable maximum number of temporal layers having a plurality of temporal layer IDs including the temporal layer ID.

In one example, the processing circuit may determine the context model from two context models of CABAC based on the block size information of the current block and a threshold. The processing circuit may determine the value of the flag using CABAC with the determined context model.

In one example, the block size information of the current block indicates at least one of: (i) width of the current block; (ii) the height of the current block; and (iii) the number of luma samples in the current block.

In one example, the plurality of accuracies that may be used for the component of the MVD of the current block include a quarter-Pel (1/4-Pel) accuracy, a 1/2-Pel accuracy, a 1-Pel (1-Pel) accuracy, and a 4-Pel (4-Pel) accuracy. The flag indicating whether 1/2-Pel precision is used may be signaled after the flag indicating whether 1-Pel precision is used and after the flag indicating whether 1/4-Pel precision is used.

In one example, the plurality of accuracies that may be used for the component of the MVD of the current block include 1/4-Pel accuracy, 1/2-Pel accuracy, 1-Pel accuracy, and 4-Pel accuracy. A flag indicating whether 1/2-Pel precision is used may be signaled before a flag indicating whether 4-Pel precision or 1-Pel precision is used. A value of 0 for the flag indicating whether 4-Pel precision or 1-Pel precision is used indicates that 4-Pel precision is used. A value of 1 for the flag indicating whether 4-Pel precision or 1-Pel precision is used indicates that 1-Pel precision is used.

In one example, the plurality of accuracies that may be used for the component of the MVD of the current block include 1/4-Pel accuracy, 1/2-Pel accuracy, 1-Pel accuracy, and 4-Pel accuracy. The plurality of accuracies is encoded using a fixed length codec having a first binary number and a second binary number, the first binary number indicating whether fractional accuracy is used.

Aspects of the present disclosure provide methods and apparatus for video encoding/decoding. In some examples, an apparatus for video decoding includes a processing circuit. The processing circuitry may be operative to decode the codec information for the current block from the encoded video bitstream. The codec information may indicate whether the current block uses an optional 1/4-Pel Interpolation Filter (IF). In response to the codec information indicating that the current block uses the optional 1/4-Pel IF, the processing circuit may reconstruct samples in the current block based on the optional 1/4-Pel IF.

In one example, the codec information includes a flag indicating whether the current block uses an optional 1/4-Pel IF.

In one example, the processing circuit may determine to use an optional 1/4-Pel IF based on the codec information. The CPMVP merge candidates in the merge candidate list of neighboring blocks to the current block include a flag of the current block and an MV, wherein the flag indicates that an optional 1/4-Pel IF is used.

In one example, the processing circuitry may prune the merge candidate list for neighboring blocks of the current block, the pruning may be based on motion information and a flag indicating whether each CPMVP merge candidate of at least one CPMVP merge candidate in the merge candidate list uses an optional 1/4-Pel IF. The at least one CPMVP merge candidate may include the above CPMVP merge candidate.

Aspects of the present disclosure also provide a non-transitory computer-readable medium storing instructions that, when executed by a computer for video decoding, cause the computer to perform any of the methods for video decoding.

Drawings

Other features, nature, and various advantages of the disclosed subject matter can be more apparent from the following detailed description and the accompanying drawings in which:

Fig. 1 is a schematic diagram of a current block and its surrounding spatial merge candidate blocks in one embodiment.

Fig. 2 is a schematic diagram of a simplified block diagram of a communication system of an embodiment.

Fig. 3 is a schematic diagram of a simplified block diagram of a communication system of another embodiment.

Fig. 4 is a schematic diagram of a simplified block diagram of a decoder of an embodiment.

Fig. 5 is a schematic diagram of a simplified block diagram of an encoder of an embodiment.

Fig. 6 is a block diagram of an encoder of another embodiment.

Fig. 7 is a block diagram of a decoder of another embodiment.

Fig. 8A is a schematic diagram of affine motion patterns of blocks in one embodiment.

Fig. 8B is a schematic diagram of affine motion patterns of a block in another embodiment.

Fig. 9 is a schematic diagram of sub-block based affine motion compensation of one embodiment.

Fig. 10A is a schematic diagram of candidate CUs of a CU of an embodiment.

Fig. 10B is a schematic diagram of control point motion vector inheritance for one embodiment.

FIG. 11 is a schematic diagram of candidate locations for creating affine merge candidate blocks, according to one embodiment.

FIG. 12 is a flow diagram of a method of one embodiment.

Fig. 13 is a flow diagram of a method of another embodiment.

Fig. 14 is a flow diagram of a method of yet another embodiment.

FIG. 15 is a schematic diagram of a computer system of one embodiment.

Detailed Description

Fig. 2 shows a simplified block diagram of a communication system (200) according to an embodiment of the disclosure. The communication system (200) comprises a plurality of terminal devices which can communicate with each other via, for example, a network (250). For example, the communication system (200) includes a first pair of terminal devices (210) and terminal devices (220) interconnected by a network (250). In the embodiment of fig. 2, the first pair of terminal devices (210) and (220) perform unidirectional data transmission. For example, the terminal device (210) may encode video data (e.g., a video image stream collected by the terminal device (210)) for transmission over the network (250) to another terminal device (220). The encoded video data may be transmitted in one or more encoded video code streams. The terminal device (220) may receive the encoded video data from the network (250), decode the encoded video data, recover the video data, and display the video image based on the recovered video data. Unidirectional data transmission is common in applications such as media services.

In another embodiment, the communication system (200) comprises a second pair of terminal devices (230) and terminal devices (240) for performing bi-directional transmission of encoded video data that may occur, for example, during a video conference. For bi-directional data transmission, in one embodiment, each of the terminal device (230) and the terminal device (240) may encode video data (e.g., a video image stream captured by the terminal device) for transmission over the network (250) to the other of the terminal device (230) and the terminal device (240). Each of the terminal device (230) and the terminal device (240) may also receive encoded video data transmitted by the other of the terminal device (230) and the terminal device (240), and may decode the encoded video data, recover the video data, and may display a video image at an accessible display device according to the recovered video data.

In the fig. 2 embodiment, examples of the terminal device (210), the terminal device (220), the terminal device (230), and the terminal device (240) may include a server, a personal computer, and a smart phone, but the principles disclosed herein may not be limited thereto. The embodiments disclosed herein are applicable to notebook computers, tablet computers, media players, and/or dedicated video conferencing devices. Network (250) represents any number of networks that transfer encoded video data between terminal device (210), terminal device (220), terminal device (230), and terminal device (240), including, for example, wired (or connected) and/or wireless communication networks. The communication network (250) may exchange data in circuit-switched and/or packet-switched channels. Representative networks include telecommunication networks, local area networks, wide area networks, and/or the internet. For purposes of this discussion, the architecture and topology of the network (250) may not be critical to the operation disclosed herein unless explained below.

As an application embodiment of the disclosed subject matter, fig. 3 shows an arrangement of a video encoder and a video decoder in a streaming environment. The subject matter disclosed herein is equally applicable to other video-enabled applications including, for example, video conferencing, digital TV, storing compressed video on digital media including CDs, DVDs, memory sticks, etc.

The streaming system may include an acquisition subsystem (313) that may include a video source (301) such as a digital camera that creates, for example, an uncompressed video image stream (302). In one embodiment, the video image stream (302) includes samples taken by a digital camera. The video image stream (302) is depicted with bold lines to emphasize its high data volume compared to the encoded video data (304) (or encoded video code stream), which can be processed by an electronic device (320) comprising a video encoder (303) coupled to a video source (301). The video encoder (303) may include hardware, software, or a combination of hardware and software, implementing or implementing aspects of the disclosed subject matter as described in more detail below. The encoded video data (304) (or encoded video code stream (304)) is depicted with thin lines compared to the video image stream (302) to emphasize its lower data volume, which may be stored on a streaming server (305) for future use. One or more streaming client sub-systems, such as client sub-system (306) and client sub-system (308) in fig. 3, may access streaming server (305), retrieve copies (307) and copies (309) of encoded video data (304). The client subsystem (306) may include, for example, a video decoder (310) in an electronic device (330). A video decoder (310) decodes an incoming copy (307) of the encoded video data and generates a video image output stream (311) that can be presented on a display (312) (e.g., a display screen) or another presentation device (not shown). In some streaming systems, encoded video data (304), video data (307), and video data (309) (e.g., a video bitstream) may be encoded according to some video encoding/compression standards. Examples of such standards include ITU-T.265 recommendations. In one embodiment, the video coding standard being developed is informally referred to as the next generation video coding (Versatile Video Coding, VVC) standard. The presently disclosed subject matter may be used in the context of VVC standards.

It should be noted that the electronic device (320) and the electronic device (330) may include other components (not shown). For example, the electronic device (320) may include a video decoder (not shown), while the electronic device (330) may also include a video encoder (not shown).

Fig. 4 is a block diagram of a video decoder (410) according to an embodiment of the disclosure. The video decoder (410) may be disposed in the electronic device (430). The electronic device (430) may include a receiver (431) (e.g., a receiving circuit). The video decoder (410) may be used in place of the video decoder (310) in the embodiment of fig. 3.

A receiver (431) may receive one or more encoded video sequences to be decoded by the video decoder (410); in the same or another embodiment, one encoded video sequence is received at a time, wherein the decoding of each encoded video sequence is independent of the other encoded video sequences. The encoded video sequence may be received from a channel (401), which may be a hardware/software link to a storage device storing encoded video data. The receiver (431) may receive encoded video data as well as other data, e.g. encoded audio data and/or auxiliary data streams, which may be forwarded to their respective use entities (not shown). The receiver (431) may separate the encoded video sequence from other data. To prevent network jitter, a buffer memory (415) may be coupled between the receiver (431) and the entropy decoder/parser (420) (hereinafter "parser (420)"). In some applications, the buffer memory (415) is part of the video decoder (410). In other applications, the buffer memory (415) may be external (not shown) to the video decoder (410). In still other applications, other buffer memory (not shown) may be provided external to the video decoder (410), e.g., to prevent network jitter, and another buffer memory (415) may be present internal to the video decoder (410), e.g., to handle playout timing. It may also be unnecessary to configure the buffer memory (415) or make it smaller when the receiver (431) receives data from a store/forward device with sufficient bandwidth and controllability or from an isochronous network. For use over best effort packet networks such as the internet, a buffer memory (415) may be required, which may be relatively large and of adaptive size, and may even be implemented at least in part in an operating system or similar element (not shown) external to the video decoder (410).

The video decoder (410) may include a parser (420) to reconstruct the symbols (421) from the encoded video sequence. The categories of these symbols include information for managing the operation of the video decoder (410), as well as information that may be used to control a display device such as the display device (412) (e.g., a display screen) that is not an integral part of the electronic device (430), but that may be coupled to the electronic device (430), as shown in fig. 4. The control information for the display device may take the form of auxiliary enhancement information (Supplemental Enhancement Information, SEI message) or video availability information (Video Usability Information, VUI) parameter set fragments (not shown). A parser (420) may parse/entropy decode the received encoded video sequence. The encoding of the encoded video sequence may be in accordance with video encoding techniques or standards, and may follow various principles, including variable length encoding, huffman coding (Huffman coding), arithmetic coding with or without context sensitivity, and the like. Based on at least one parameter corresponding to the group, a parser (420) may extract a subgroup parameter set for at least one subgroup of pixels in the video decoder from the encoded video sequence. A subgroup may include a group of pictures (Group of Pictures, GOP), pictures, tiles, slices, macroblocks, coding Units (CUs), blocks, transform Units (TUs), prediction Units (PUs), and the like. The parser (420) may also extract information, such as transform coefficients, quantizer parameter values, motion vectors, etc., from the encoded video sequence.

The parser (420) may perform entropy decoding/parsing operations on the video sequence received from the buffer memory (415), thereby creating symbols (421).

The reconstructed symbol (421) may involve a plurality of different units depending on the type of encoded video image or a portion of the encoded video image (e.g., inter and intra images, inter and intra blocks), and other factors. Which units are involved and how are controlled by subgroup control information that a parser (420) parses from the encoded video sequence. For brevity, such a sub-group control information flow between the parser (420) and the various units below is not described.

In addition to the functional blocks already mentioned, the video decoder (410) may be conceptually subdivided into several functional units as described below. In practical embodiments operating under commercial constraints, many of these units interact closely with each other and may be at least partially integrated with each other. However, for the purpose of describing the disclosed subject matter, it is suitable to conceptually subdivide into the following functional units.

The first unit is a scaler/inverse transform unit (451). The sealer/inverse transform unit (451) receives quantized transform coefficients as symbols (421) from the parser (420) along with control information, including which transform, block size, quantization factor, quantization scaling matrix, etc. to use. The sealer/inverse transform unit (451) may output a block comprising sample values, which may be input into the aggregator (455).

In some cases, the output samples of the scaler/inverse transform unit (451) may relate to intra-coded blocks; namely: blocks of predictive information from previously reconstructed portions of the current image are not used but may be used. Such predictive information may be provided by an intra image prediction unit (452). In some cases, the intra image prediction unit (452) uses surrounding reconstructed information extracted from the current image buffer (458) to generate a block of the same size and shape as the block being reconstructed. For example, the current image buffer (458) buffers a partially reconstructed current image and/or a fully reconstructed current image. In some cases, the aggregator (455) adds the prediction information generated by the intra prediction unit (452) to the output sample information provided by the scaler/inverse transform unit (451) on a per sample basis.

In other cases, the output samples of the scaler/inverse transform unit (451) may involve inter-coding and potential motion compensation blocks. In this case, the motion compensated prediction unit (453) may access the reference picture store (457) to extract samples for prediction. After motion compensation of the extracted samples according to the symbols (421) related to the block, these samples may be added by an aggregator (455) to the output of the sealer/inverse transform unit (451), in this case referred to as residual samples or residual signals, generating output sample information. The motion compensated prediction unit (453) obtains prediction samples from addresses in the reference image memory (457), which addresses may be controlled by motion vectors, which motion vectors in the form of symbols (421) may have, for example, X, Y and reference image components, for use by the motion compensated prediction unit (453). The motion compensation may also include interpolation of sample values extracted from a reference image memory (457) when sub-sampling accurate motion vectors are used, motion vector prediction mechanisms, etc.

The output samples of the aggregator (455) may undergo various loop filtering techniques in a loop filter unit (456). Video compression techniques may include in-loop filter techniques that are controlled by parameters included in an encoded video sequence (also referred to as an encoded video bitstream) and that are available to a loop filter unit (456) as symbols (421) from a parser (420), but video compression techniques may also be responsive to meta-information obtained during decoding of a previous (in decoding order) portion of an encoded image or encoded video sequence, and to previously reconstructed and loop filtered sample values.

The output of the loop filter unit (456) may be a stream of samples that may be output to a display device (412) and stored in a reference image memory (457) for future inter-image prediction.

Once fully reconstructed, some of the encoded pictures can be used as reference pictures for future prediction. For example, once an encoded image corresponding to a current image is fully reconstructed and the encoded image is identified (by, for example, a parser (420)) as a reference image, the current image buffer (458) may become part of the reference image memory (457) and a new current image buffer may be reallocated before starting to reconstruct a subsequent encoded image.

The video decoder (410) may perform decoding operations according to a predetermined video compression technique in the ITU-t h.265, etc. standard. The coded video sequence may conform to the syntax specified by the video compression technique or standard used in the sense that the coded video sequence follows the syntax of the video compression technique or standard and the configuration files recorded in the video compression technique or standard. In particular, a profile may select some tools from all tools available in a video compression technology or standard as the only tools available under the profile. To be satisfactory, the complexity of the encoded video sequence must also lie within the limits defined by the level of video compression techniques or standards. In some cases, the hierarchy limits a maximum image size, a maximum frame rate, a maximum reconstructed sample rate (e.g., measured in megasamples per second), a maximum reference image size, and so forth. In some cases, the limits set by the hierarchy may be further defined by hypothetical reference decoder (Hypothetical Reference Decoder, HRD) specifications and HRD buffer management metadata sent in the encoded video sequence.

In one embodiment, the receiver (431) may receive the encoded video and additional (redundant) data. The additional data may be considered part of the encoded video sequence. The additional data may be used by the video decoder (410) 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 (signal noise ratio, SNR) enhancement layers, redundant slices, redundant pictures, forward error correction codes, and the like.

Fig. 5 is a block diagram of a video encoder (503) according to an embodiment of the present disclosure. The video encoder (503) is disposed in the electronic device (520). The electronic device (520) includes a transmitter (540) (e.g., a transmission circuit). A video encoder (503) may be used in place of the video encoder (303) in the embodiment of fig. 3.

The video encoder (503) may receive video samples from a video source (501) (not part of the electronic device (520) in the embodiment of fig. 5) that may acquire video images to be encoded by the video encoder (503). In another embodiment, the video source (501) is part of an electronic device (520).

The video source (501) may provide a source video sequence in the form of a stream of digital video samples to be encoded by the video encoder (503), which may have any suitable bit depth (e.g., 8 bits, 10 bits, 12 bits … …), any color space (e.g., BT.601YCrCB, RGB … …), and any suitable sampling structure (e.g., YCrCb4:2:0, YCrCb4: 4:4). In a media service system, a video source (501) may be a storage device that stores previously prepared video. In a video conferencing system, the video source (501) may be a camera that collects local image information as a video sequence. The video data may be provided as a plurality of individual images which, when viewed in sequence, are given motion. The image itself may be constructed as a spatial pixel array, 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 those skilled in the art. The following focuses on describing sampling.

According to an embodiment, the video encoder (503) may encode and compress the images of the source video sequence into an encoded video sequence (543) in real time or under any other temporal constraint required by the application. Performing the proper encoding speed is a function of the controller (550). In some embodiments, a controller (550) controls and is functionally coupled to other functional units as described below. For simplicity, the coupling is not shown. The parameters set by the controller (550) may include rate control related parameters (picture skip, quantizer, lambda value for rate distortion optimization techniques, etc.), picture size, picture group (group of pictures, GOP) layout, maximum motion vector search range, etc. The controller (550) may be used to have other suitable functions related to the video encoder (503) optimized for a certain system design.

In some embodiments, a video encoder (503) is used to operate in an encoding loop. As a simple description, in one embodiment, the encoding loop may include a source encoder (530) (e.g., responsible for creating symbols, such as a symbol stream, based on the input image and reference image to be encoded) and a (local) decoder (533) embedded in the video encoder (503). The decoder (533) reconstructs the symbols in a similar manner to the (remote) decoder creating the sampled data to create the sampled data (since any compression between the symbols and the encoded video stream is lossless in the video compression technique considered in the disclosed subject matter). The reconstructed sample stream (sample data) is input to a reference picture store (534). Since decoding of the symbol stream produces a bit-accurate result independent of the decoder location (local or remote), the content in the reference picture store (534) is also bit-accurate 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 as the sample values "seen" when the decoder would use prediction during decoding. This reference picture synchronicity rationale (and drift that occurs in the event that synchronicity cannot be maintained due to channel errors, for example) is also used in some related art.

The operation of the "local" decoder (533) may be the same as, for example, the "remote" decoder of the video decoder (410) that has been described in detail above in connection with fig. 4. However, referring briefly to fig. 4 in addition, when a symbol is available and the entropy encoder (545) and the parser (420) are able to losslessly encode/decode the symbol into an encoded video sequence, the entropy decoding portion of the video decoder (410), including the buffer memory (415) and the parser (420), may not be implemented entirely in the local decoder (533).

It can be observed at this point that any decoder technique other than the parsing/entropy decoding present in the decoder must also be present in the corresponding encoder in substantially the same functional form. For this reason, the disclosed subject matter focuses on decoder operation. The description of the encoder technique may be simplified because the encoder technique is reciprocal to the fully described decoder technique. A more detailed description is required only in certain areas and is provided below.

During operation, in some embodiments, the source encoder (530) may perform motion compensated predictive encoding. The motion compensated predictive coding predictively codes an input image with reference to one or more previously coded images from a video sequence designated as "reference images". In this way, the encoding engine (532) encodes differences between blocks of pixels of an input image and blocks of pixels of a reference image, which may be selected as a prediction reference for the input image.

The local video decoder (533) may decode encoded video data of an image specifiable as a reference image based on the symbol created by the source encoder (530). Advantageously, the operation of the encoding engine (532) may be a lossy process. When encoded video data may be decoded at a video decoder (not shown in fig. 5), the reconstructed video sequence may typically be a copy of the source video sequence with some errors. The local video decoder (533) repeats the decoding process, which may be performed on the reference picture by the video decoder, and may cause the reconstructed reference picture to be stored in the reference picture cache (534). In this way, the video encoder (503) may locally store a copy of the reconstructed reference picture that has common content (no transmission errors) with the reconstructed reference picture to be obtained by the remote video decoder.

The predictor (535) may perform a predictive search for the encoding engine (532). That is, for a new image to be encoded, the predictor (535) may search the reference image memory (534) for sample data (as candidate reference pixel blocks) or some metadata, such as reference image motion vectors, block shapes, etc., that may be suitable prediction references for the new image. The predictor (535) may operate on a block of samples by block of pixels basis to find a suitable prediction reference. In some cases, from the search results obtained by the predictor (535), it may be determined that the input image may have prediction references derived from a plurality of reference images stored in a reference image memory (534).

The controller (550) may manage the encoding operations of the source encoder (530) including, for example, setting parameters and subgroup parameters for encoding video data.

The outputs of all of the above functional units may be entropy encoded in an entropy encoder (545). An entropy encoder (545) losslessly compresses symbols generated by various functional units according to techniques such as Huffman coding, variable length coding, arithmetic coding, and the like, thereby converting the symbols into an encoded video sequence.

The transmitter (540) may buffer the encoded video sequence created by the entropy encoder (545) in preparation for transmission over a communication channel (560), which may be a hardware/software link to a storage device that is to store encoded video data. The transmitter (540) may combine the encoded video data from the video encoder (503) with other data to be transmitted, such as encoded audio data and/or an auxiliary data stream (source not shown).

The controller (550) may manage the operation of the video encoder (503). During encoding, the controller (550) may assign each encoded image a certain encoded image type, which may affect the encoding techniques applicable to the respective image. For example, images may be generally assigned to one of the following image types:

An intra picture (I picture) may be a picture that can be encoded and decoded without using any other picture in the sequence as a prediction source. Some video codecs allow for different types of intra pictures, including, for example, independent decoder refresh (Independent Decoder Refresh, "IDR") pictures. Those skilled in the art will recognize those variations of the I image and their corresponding applications and features.

A predictive picture (P-picture) may be a picture that can be encoded and decoded using intra-or inter-prediction that predicts sample values for each block using at most one motion vector and a reference index.

A bi-predictive picture (B-picture) may be a picture that can be encoded and decoded using intra-or inter-prediction that predicts sample values for each block using at most two motion vectors and a reference index. Similarly, more than two reference pictures and associated metadata may be used by the multiple predictive pictures for reconstructing a single block.

The source image may typically be spatially sub-divided into multiple blocks of samples (e.g., blocks of 4 x 4, 8 x 8, 4 x 8, or 16 x 16 samples each) and encoded on a block-by-block basis. A block may be predictive coded with reference to other (coded) blocks, which are determined from the coding allocation applied to the respective pictures of the block. For example, a block of an I picture may be non-predictive coded, or the block may be predictive coded (spatial prediction or intra prediction) with reference to an already coded block of the same picture. The pixel blocks of the P picture may be predictively coded by spatial prediction or by temporal prediction with reference to a previously coded reference picture. The block of B pictures may be predictively coded by spatial prediction or by temporal prediction with reference to one or two previously coded reference pictures.

The video encoder (503) may perform encoding operations according to a predetermined video encoding technique or standard, such as the ITU-t h.265 recommendation. In operation, the video encoder (503) may perform various compression operations, including predictive coding operations that exploit temporal and spatial redundancies in the input video sequence. Thus, the encoded video data may conform to the syntax specified by the video encoding technique or standard used.

In one embodiment, the transmitter (540) may transmit the additional data and the encoded video. The source encoder (530) may take such data as part of the encoded video sequence. The additional data may include temporal/spatial/SNR enhancement layers, redundant pictures and slices, other forms of redundant data, SEI messages, VUI parameter set slices, and the like.

The acquired video may be taken as a plurality of source images (video images) in a time series. Intra-picture prediction (often abbreviated as intra-prediction) exploits spatial correlation in a given picture, while inter-picture prediction exploits (temporal or other) correlation between pictures. In one embodiment, the particular image being encoded/decoded is partitioned into blocks, and the particular image being encoded/decoded is referred to as the current image. When a block in the current image is similar to a reference block in a reference image that has been previously encoded and still buffered in the video, the block in the current image may be encoded by a vector called a motion vector. The motion vector points to a reference block in a reference picture, and in the case of using multiple reference pictures, the motion vector may have a third dimension that identifies the reference picture.

In some embodiments, bi-prediction techniques may be used in inter-picture prediction. According to bi-prediction techniques, two reference pictures are used, e.g., a first reference picture and a second reference picture, that are both prior to the current picture in the video in decoding order (but may be past and future, respectively, in display order). The block in the current image may be encoded by a first motion vector pointing to a first reference block in the first reference image and a second motion vector pointing to a second reference block in the second reference image. The block may be predicted by a combination of the first reference block and the second reference block.

Furthermore, merge mode techniques may be used in inter-picture prediction to improve coding efficiency.

According to some embodiments of the present disclosure, prediction such as inter-image prediction and intra-image prediction is performed in units of blocks. For example, according to the HEVC standard, pictures in a video picture sequence are partitioned into Coding Tree Units (CTUs) for compression, with CTUs in the pictures having the same size, e.g., 64 x 64 pixels, 32 x 32 pixels, or 16 x 16 pixels. In general, a CTU includes three coding tree blocks (coding tree block, CTB), which are one luma CTB and two chroma CTBs. Each CTU quadtree may be further split into one or more Coding Units (CUs). For example, a 64×64 pixel CTU may be split into one 64×64 pixel CU, or 4 32×32 pixel CUs, or 16 16×16 pixel CUs. In one embodiment, each CU is analyzed to determine a prediction type, such as an inter prediction type or an intra prediction type, for the CU. Depending on temporal and/or spatial predictability, a CU is split into one or more Prediction Units (PUs). In general, each PU includes a luminance Prediction Block (PB) and two chrominance PB. In one embodiment, a prediction operation in encoding (encoding/decoding) is performed in units of prediction blocks. An embodiment using a luminance prediction block as the prediction block includes a matrix of pixel values (e.g., luminance values), such as 8×8 pixels, 16×16 pixels, 8×16 pixels, 16×8 pixels, and the like.

Fig. 6 is a diagram of a video encoder (603) according to another embodiment of the present disclosure. A video encoder (603) is for receiving a processing block (e.g., a prediction block) of sample values within a current video image in a sequence of video images and encoding the processing block into an encoded image that is part of the encoded video sequence. In one embodiment, a video encoder (603) is used in place of the video encoder (303) in the embodiment of fig. 3.

In an HEVC embodiment, a video encoder (603) receives a matrix of sample values for a processing block, such as an 8 x 8 sample prediction block or the like. The video encoder (603) uses, for example, rate distortion optimization to determine whether to encode the processing block using intra mode, inter mode, or bi-predictive mode. When encoding a processing block in intra mode, the video encoder (603) may use intra-prediction techniques to encode the processing block into the encoded image; and when encoding the processing block in inter mode or bi-predictive mode, the video encoder (603) may encode the processing block into the encoded image using inter-prediction or bi-prediction techniques, respectively. In some video coding techniques, the merge mode may be an inter-picture predictor mode in which motion vectors are derived from one or more motion vector predictors without resorting to coded motion vector components outside of the predictor. In some other video coding techniques, there may be motion vector components that are applicable to the subject block. In one embodiment, the video encoder (603) includes other components, such as a mode decision module (not shown) for determining the mode of the processing block.

In the embodiment of fig. 6, the video encoder (603) includes an inter-frame encoder (630), an intra-frame encoder (622), a residual calculator (623), a switch (626), a residual encoder (624), a general controller (621), and an entropy encoder (625) coupled together as shown in fig. 6.

An inter-frame encoder (630) is used to receive samples of a current block (e.g., a processing block), compare the block to one or more of the reference blocks (e.g., blocks in a previous image and a subsequent image), generate inter-frame prediction information (e.g., redundancy information description, motion vectors, merge mode information according to inter-frame coding techniques), and calculate inter-frame prediction results (e.g., predicted blocks) based on the inter-frame prediction information using any suitable technique. In some embodiments, the reference picture is a decoded reference picture that is decoded based on the encoded video information.

An intra encoder (622) is used to receive samples of a current block (e.g., a processed block), in some cases compare the block to blocks already encoded in the same image, generate quantized coefficients after transformation, and in some cases also generate intra prediction information (e.g., according to intra prediction direction information of one or more intra coding techniques). In one embodiment, the intra-encoder (622) also calculates an intra-prediction result (e.g., a predicted block) based on the intra-prediction information and a reference block in the same picture.

A universal controller (621) is used to determine universal control data and control other components of the video encoder (603) based on the universal control data. In one embodiment, a general purpose controller (621) determines a mode of the block and provides a control signal to a switch (626) based on the mode. For example, when the mode is an intra mode, the general controller (621) controls the switch (626) to select an intra mode result for use by the residual calculator (623), and controls the entropy encoder (625) to select intra prediction information and add the intra prediction information in the bitstream; and when the mode is an inter mode, the general controller (621) controls the switch (626) to select an inter prediction result for use by the residual calculator (623), and controls the entropy encoder (625) to select inter prediction information and add the inter prediction information in the bitstream.

The residual calculator (623) is configured to calculate a difference (residual data) between the received block and a prediction result selected from the intra-encoder (622) or the inter-encoder (630). A residual encoder (624) is operative to encode residual data based on the residual data to generate transform coefficients. In one embodiment, a residual encoder (624) is used to convert residual data from the spatial domain to the frequency domain and generate transform coefficients. The transform coefficients are then processed through quantization to obtain quantized transform coefficients. In various embodiments, the video encoder (603) further comprises a residual decoder (628). A residual decoder (628) is used to perform the inverse transform and generate decoded residual data. The decoded residual data may be suitably used by the intra-encoder (622) and the inter-encoder (630). For example, inter-encoder (630) may generate a decoded block based on the decoded residual data and the inter-prediction information, and intra-encoder (622) may generate a decoded block based on the decoded residual data and the intra-prediction information. The decoded blocks are processed appropriately to generate decoded images, and in some embodiments, the decoded images may be buffered in a memory circuit (not shown) and used as reference images.

An entropy encoder (625) is used to format the code stream to produce encoded blocks. The entropy encoder (625) generates various information according to suitable standards, such as the HEVC standard. In one embodiment, the entropy encoder (625) is configured to include general control data, selected prediction information (e.g., intra prediction information or inter prediction information), residual information, and other suitable information in the bitstream. It should be noted that, according to the disclosed subject matter, when a block is encoded in an inter mode or a merge sub-mode of a bi-prediction mode, there is no residual information.

Fig. 7 is a diagram of a video decoder (710) according to another embodiment of the present disclosure. A video decoder (710) is configured to receive encoded pictures that are part of an encoded video sequence and decode the encoded pictures to generate reconstructed pictures. In one embodiment, a video decoder (710) is used in place of the video decoder (310) in the embodiment of fig. 3.

In the fig. 7 embodiment, video decoder (710) includes an entropy decoder (771), an inter decoder (780), a residual decoder (773), a reconstruction module (774), and an intra decoder (772) coupled together as shown in fig. 7.

An entropy decoder (771) is operable to reconstruct certain symbols from an encoded picture, the symbols representing syntax elements that constitute the encoded picture. Such symbols may include, for example, a mode in which the block is encoded (e.g., an intra mode, an inter mode, a bi-predictive mode, a merge sub-mode of the latter two, or another sub-mode), prediction information (e.g., intra prediction information or inter prediction information) that may identify certain samples or metadata used by the intra decoder (772) or the inter decoder (780), respectively, for prediction, residual information in the form of, for example, quantized transform coefficients, and the like. In one embodiment, when the prediction mode is an inter prediction mode or a bi-directional prediction mode, inter prediction information is provided to an inter decoder (780); and providing the intra prediction information to an intra decoder (772) when the prediction type is an intra prediction type. The residual information may be provided to a residual decoder (773) via inverse quantization.

An inter decoder (780) is configured to receive inter prediction information and generate an inter prediction result based on the inter prediction information.

An intra decoder (772) is configured to receive intra prediction information and generate a prediction result based on the intra prediction information.

A residual decoder (773) is used to perform inverse quantization to extract dequantized transform coefficients, and to process the dequantized transform coefficients to transform a residual from the frequency domain to the spatial domain. The residual decoder (773) may also need some control information (to include quantizer parameters (Quantizer Parameter, QP)) and that information may be provided by the entropy decoder (771) (data path not shown because this is a low amount of control information).

A reconstruction module (774) is used to combine the residual output by the residual decoder (773) with the prediction result (as may be output by the inter prediction module or the intra prediction module as appropriate) in the spatial domain to form a reconstructed block, which may be part of a reconstructed image, which in turn may be part of a reconstructed video. It should be noted that other suitable operations, such as deblocking operations, may be performed to improve visual quality.

It should be noted that video encoder (303), video encoder (503) and video encoder (603), as well as video decoder (310), video decoder (410) and video decoder (710) may be implemented using any suitable technique. In one embodiment, video encoder (303), video encoder (503) and video encoder (603), and video decoder (310), video decoder (410) and video decoder (710) may be implemented using one or more integrated circuits. In another embodiment, the video encoder (303), the video encoder (503) and the video encoder (603), and the video decoder (310), the video decoder (410) and the video decoder (710) may be implemented using one or more processors executing software instructions.

Aspects of the present disclosure relate to methods of inter prediction, such as Adaptive Motion Vector Resolution (AMVR) in conventional inter motion vector difference (inter motion vector difference, MVD) coding, affine MVD coding, and Symmetric MVD (SMVD) coding in advanced video codecs.

In various embodiments, for inter-predicted CUs, motion parameters may be used for sample generation for inter-prediction, including motion vectors, reference picture indices, reference picture list use indices, and/or other additional information. Inter-prediction may include unidirectional prediction, bi-directional prediction, and/or other prediction modes. In unidirectional prediction, a reference picture list (e.g., a first reference picture list or list 0 (L0), a second reference picture list or list 1 (L1)) may be used. In bi-prediction, both L0 and L1 may be used. The reference picture list use index may indicate that the reference picture list includes L0, L1, or L0 and L1.

The motion parameters may be signaled explicitly or implicitly. When a CU is encoded in skip mode, the CU may be associated with one PU and may have no significant residual coefficients (e.g., zero residual coefficients), no encoded Motion Vector Differences (MVDs), or no reference picture indices.

A merge mode may be used in which the motion parameters of the current CU may be obtained from a neighboring CU, which includes spatial and temporal merge candidate CUs, and optionally other merge candidate CUs. The merge mode may be applied to inter-predicted CUs and may be used for a skip mode. In other examples, the motion parameter may be explicitly transmitted or signaled. For example, a motion vector, a reference picture index corresponding to each reference picture list, a reference picture list use flag, and other information may be explicitly signaled for each CU.

In some embodiments, one or more of the following inter-prediction codec tools may be used: (1) extended merge prediction; (2) Merge mode with motion vector difference (merge mode with motion vector difference, MMVD); (3) Advanced motion vector prediction (advanced motion vector prediction, AMVP) mode with symmetric MVD signaling; (4) affine motion compensated prediction; (5) Temporal motion vector prediction based on sub-blocks (sub-block-based temporal motion vector prediction, sbTMVP); (6) Adaptive motion vector resolution (adaptive motion vector resolution, AMVR); (7) Bi-prediction with weighted average (bi-prediction with weighted averaging, BWA); (8) Bidirectional optical flow (bi-directional optical flow, BDOF); (9) Decoder-side motion vector correction (decoder side motion vector refinement, DMVR); (10) triangle partition prediction; and (11) combined inter and intra prediction (combined inter and intra prediction, CIIP).

In some examples, a translational motion model is applied to the motion compensated prediction (motion compensation prediction, MCP). Block-based affine motion compensation (also referred to as affine motion compensation prediction, affine motion compensation method, affine motion prediction, affine motion model, affine transformation motion compensation prediction) can be applied, for example, to model various types of motion, such as zoom-in/out, rotation, perspective motion, and other irregular motions (e.g., motions other than translational motion).

In fig. 8A, when a 4-parameter affine model (or a 4-parameter affine motion model) is used, affine motion fields of a block (810A) are described with motion information of two Control Points (CPs) (CP 0 and CP 1). The motion information may include two MVs or control points MV (control point motion vector, CPMV) of CP0 and CP1, CPMV0 and CPMV1, respectively. In fig. 8B, when a 6-parameter affine model (or 6-parameter affine motion model) is used, affine motion fields of the block (810B) are described by motion information of three CPs, i.e., CP0-CP 2. The motion information may include three MVs or CPMVs of CP0-CP2, CPMVs 0-CPMVs 2, respectively.

For a 4-parameter affine motion model, the motion vectors at sample positions (x, y) in block (810A) can be derived as:

Wherein (mv) _0x ,mv _0y ) MV (CPMV 0) which is the upper left CP (CP 0), (MV _1x ,mv _1y ) MV (CPMV 1) which is the upper right CP (CP 1). The coordinates (x, y) are relative to the upper left sample of the block (810A), W representing the width of the block (810A).

For a 6-parameter affine motion model, the motion vectors at sample positions (x, y) in block (810B) can be derived as:

wherein (mv) _0x ,mv _0y ) MV (CPMV 0) which is the upper left corner CP (CP 0), (MV _1x ,mv _1y ) MV (CPMV 1) which is the upper right corner CP (CP 1), (MV _2x ,mv _2y ) Is MV (CPMV 2) of the lower left corner CP (CP 2). Coordinates (x, y) are relative to the upper left sample of block (810B), W represents the width of block (810B), and H represents the height of block (810B).

As shown in fig. 9, to simplify motion compensated prediction, sub-block based affine motion compensation (also referred to as sub-block based affine motion model) is applied in some embodiments. In sub-block based affine motion compensation, a current block (e.g., a luminance block) (900) may be divided into a plurality of sub-blocks (also referred to as affine sub-blocks) (902). The MVs (also referred to as sub-blocks MVs) may be used to represent MVs (901) for individual samples of each of a plurality of sub-blocks (902). In one example, the sub-block MV (901) of the sub-block (902) is the MV of the center sample of the sub-block (902). Accordingly, the sub-block MV (901) may be calculated using a 4-parameter affine motion model (e.g., equation (1)), a 6-parameter affine motion model (e.g., equation (2)), or the like. Referring to fig. 9, a current block (900) is divided into 16 sub-blocks (902) having 16 sub-blocks MV (e.g., MVa-MVp) (901).

Referring to fig. 9, a 4-parameter affine motion model is used as an example.

And->

CPMVs of the upper left CP (CP 0) and the upper right CP (CP 1), respectively. To derive the sub-block MV (901) of the sub-block (902), the MV of the center sample of the sub-block (902) may be calculated according to equation (1), and rounded to a fractional accuracy of 1/16 (e.g., the accuracy of the sub-block MV is 1/16 of the sample or pixel). A motion compensated interpolation filter may be used to generate a prediction for each sub-block (902) with the derived MV (901).

The sub-block size of the chrominance component may be set to 4×4. The sub-block MV of the 4 x 4 chroma sub-block may be calculated as an average value of the sub-blocks MV of four corresponding 4 x 4 luma sub-blocks.

Similar to translational motion inter prediction, two affine motion inter prediction modes, affine MERGE mode (or affine MERGE prediction, af_merge mode) and affine AMVP mode (or affine AMVP prediction), are employed in some embodiments.

In some embodiments, an affine MERGE mode (e.g., af_merge mode) may be applied to CUs having both width and height greater than or equal to 8. In affine merge mode, the CPMV of the current CU may be generated based on motion information of spatially neighboring CUs of the current CU. Up to five candidate CPMV predictors (control point motion vector predictor, CPMVP) may be included in the candidate list (e.g., affine merge candidate list), and an index may be signaled to indicate the candidate CPMVP for the current CU. The following three types of candidate CPMVPs may be used to form an affine merge candidate list: (a) Inherited CPMVP affine merge candidates extrapolated from CPMVs of the neighboring CUs (e.g., spatially neighboring CUs); (b) Constructed CPMVP affine merge candidates derived using the translated MVs of the neighboring CUs (e.g., spatial neighboring CUs and/or temporal neighboring CUs); and/or (c) zero MV.

In one embodiment, for example in VTM (Versatile test model, multifunctional test model) 3, the candidate list (e.g., affine merge candidate list) includes at most two inherited CPMVP affine merge candidates that may be derived from affine motion models of neighboring CUs (or blocks). For example, a first inherited CPMVP affine merge candidate may be derived from a plurality of CUs adjacent to the left side, and a second inherited CPMVP affine merge candidate may be derived from a plurality of CUs adjacent above. An exemplary candidate CU (or block) for CU (1001) is shown in fig. 10A. To obtain the first inherited CPMVP affine merge candidate (or left predictor), a scan order of A0- > A1 may be used. To obtain the second inherited CPMVP affine merge candidate (or upper predictor), the scan order may be B0- > B1- > B2. In one example, only the candidate predictors of the first inheritance are selected from each side (e.g., left side and/or above). In addition, no pruning check is performed between the two inherited candidate predictors. When determining one neighboring affine CU, multiple CPMVs of the neighboring affine CU may be used to derive candidate CPMVPs in the affine merge candidate list of the current CU. As shown in fig. 10B, if adjacent lower left block a is encoded in affine motion mode, MVs including the upper left corner, upper right corner, and lower left corner of the CU (1002) of the block a can be obtained: v2, v3 and v4. When block a is encoded with a 4-parameter affine motion model, two CPMV of the current CU (1000) can be calculated from v2 and v 3. When block a is encoded with a 6-parameter affine motion model, three CPMV of the current CU (1000) can be calculated using v2, v3, and v4.

The CPMVP affine merge candidates constructed for a CU may refer to candidate CPMVPs constructed by combining neighboring translational motion information of each CP of the CU. The motion information used by the CP may be derived from a spatial neighboring block and a temporal neighboring block of the current block (1100) as shown in fig. 11. CPMV (CPMU- _k (k=1, 2, 3, 4) may represent the kth CP of the current block (1100). For CPMV ₁ Blocks B2, B3 and A2 may be checked. For example, where the scanning order is B2- > B3- > A2, the MVs of the first available block may be used as CPMVs ₁ . For CPMV ₂ Blocks B1 and B0 may be checked, for example, using a scan order of B1- > B0. For CPMV ₃ Blocks A1 and A0 may be checked, for example, using a scan order of A1- > A0. When a Temporal Motion Vector Predictor (TMVP) (indicated by T in fig. 11) is available, the TMVP may be used as a CPMV ₄ And (3) using.

After obtaining MVs of four CPs, a plurality of CPMVP affine merging candidates may be constructed based on motion information of four control points. The following combination of CPMV may be used to construct CPMVP affine merge candidates in sequence:

{CPMV ₁ ，CPMV ₂ ，CPMV ₃ }、{CPMV ₁ ，CPMV ₂ ，CPMV ₄ }、{CPMV ₁ ，CPMV ₃ ，CPMV ₄ }、{CPMV ₂ ，CPMV ₃ ，CPMV ₄ }、{CPMV ₁ ，CPMV ₂ sum { CPMV }, and ₁ ，CPMV ₃ }。

the combination of 3 CPMVs can construct 6-parameter CPMVP affine merging candidates, and the combination of 2 CPMVs can construct 4-parameter CPMVP affine merging candidates. To avoid the motion scaling procedure, if the reference indices of the control points are different, the corresponding combination of CPMV may be discarded.

After checking the inherited CPMVP affine merge candidate and the constructed CPMVP affine merge candidate, if the affine merge candidate list is not full, a zero MV may be inserted at the end of the affine merge candidate list.

In some embodiments, affine AMVP mode may be applied to CUs with both width and height greater than or equal to 16. Affine flags at CU level may be signaled in the bitstream to indicate whether affine AMVP mode is used, and then another flag may be signaled to indicate whether 4-parameter affine motion model or 6-parameter affine motion model is used. In affine AMVP mode, differences of multiple CPMVs and corresponding Cpmvpredictors (CPMVPs) of the current CU may be signaled in the bitstream. The affine AMVP candidate list may be 2 in size and may be generated by using the following four types of CPMV candidates (e.g., in the order of (a) - > (b) - > (c) - > (d)): (a) Inherited affine AMVP candidate CPMVP extrapolated from CPMVs of multiple neighbor CUs; (b) Constructed affine AMVP candidate cpmvs derived using the translated MVs of multiple neighbor CUs; (c) a translational MV from a plurality of neighboring CUs; and (d) a plurality of zero MVs.

In one example, the order of checking (or scanning order) of inherited affine AMVP candidates CPMVP is similar to or the same as the order of checking of inherited CPMVP affine merge candidates. In one example, the difference between the inherited affine AMVP candidate CPMVP and the inherited CPMVP affine merge candidate is that for the inherited affine AMVP candidate CPMVP, only affine CUs with the same reference image as the reference image in the current block are considered. When an inherited affine MV predictor (or inherited affine AMVP candidate CPMVP) is inserted into the affine AMVP candidate list, the pruning process is not performed.

The constructed AMVP candidate CPMVP may be derived from the specific specified spatial neighbors shown in fig. 11. The same order of checking as used in constructing CPMVP affine merge candidates(s) may be used. In addition, reference picture indexes of neighboring blocks may also be checked. A first block in the checking order may be used, which employs inter-frame coding and has the same reference picture as the reference picture in the current CU. When the current CU is encoded with a 4-parameter affine motion model and both CPMV1 and CPMV2 are available, the available CPMV (e.g., CPMV1 and CPMV 2) may be added as one candidate CPMVP to the affine AMVP candidate list. When the current CU is encoded with a 6-parameter affine motion mode and all three CPMV (e.g., CPMV1, CPMV2, and CPMV 3) are available, the available CPMV may be added as one candidate CPMVP to the affine AMVP candidate list. Otherwise, the constructed AMVP candidate CPMVP may be set to unavailable.

If the size of the affine AMVP candidate list is less than 2 after checking the inherited AMVP candidate CPMVP(s) and the constructed AMVP candidate CPMVP(s), the translated MV of the neighboring CU(s) of the current block (1100) may be added, so that all CPMVs of the current block (1100) are predicted when these translated MVs are available. Finally, if the affine AMVP candidate list is still not full, the affine AMVP candidate list may be populated with zero MVs.

Aspects of the present disclosure relate to AMVR methods or schemes. In some examples (e.g., in HEVC), MVDs between MVs of a block (e.g., CU, coded block) and a prediction MV (also referred to as MV predictor) may be signaled in units of quarter-luma samples (or quarter-pixel precision or 1/4-Pel precision) when one flag (e.g., use_integer_mv_flag) is equal to 0 (e.g., in a slice header). In some examples (e.g., in VVC), a CU-level AMVR scheme may be used, where the MVD of a CU may be encoded with different precision (also referred to as MVD precision or MVD resolution). The MVD resolution (or MVD precision) of a CU may be adaptively selected according to the mode of the CU (e.g., normal AMVP mode, affine AVMP mode), for example, as shown in table 1.

The conventional AMVP mode may refer to conventional inter prediction with AMVP mode signaled for the block (e.g., a coded block). In one example, the AMVR flag is signaled when AMVP mode is used.

For normal AMVP mode, the MVD resolution may specify the resolution of one or more MVDs for the block. For affine AMVP mode, the MVD resolution may specify the resolution of one or more MVDs for multiple CPs for the block.

Table 1 shows some exemplary MVD resolutions of a CU, such as the precision of components of MVDs that may be used for a CU. The available precision of the CU may include any suitable combination of precision. The available precision of a CU may depend on the prediction mode of the CU (e.g., normal AMVP mode, affine AMVP mode, IBC mode). In one example, the precision or MVD resolution includes a 1/4-Pel (or 1/4-Pel) precision, a half-pixel (1/2-Pel or 1/2-Pel) precision, a one pixel (1-Pel or 1-Pel) precision, and a four pixel (4-Pel or 4-Pel) precision of normal AMVP mode. In normal AMVP mode, samples in a CU may share the same motion information. In one example, the precision or MVD resolution includes 1/4-Pel precision, 1/16-Pel (or 1/16-Pel) precision, and 1-Pel precision of the affine AMVP mode. In affine AMVP mode, samples in a CU may have different motion information. In one example, the precision or MVD resolution includes 1-Pel precision and 4-Pel precision for IBCAMVP mode. In one example, in IBCAMVP mode, a CU in a current picture may be predicted from a block in the current picture.

Table 1: examples of MVD resolution of CUs

	AMVR type=0	AMVR type = 1	AMVR type = 2	AMVR type = 3
					Normal AMVP mode	1/4-Pel	1-Pel	4-Pel	1/2-Pel
Affine AMVP mode	1/4-Pel	1/16-Pel	1-Pel	-
					IBCAMVP mode	-	1-Pel	4-Pel	-

If the CU has at least one non-zero MVD component, a CU level MVD resolution indication may be conditionally signaled. In one example, if all MVD components (e.g., horizontal MVD and vertical MVD of reference list L0 and reference list L1) are zero, then a quarter-luminance sample MVD resolution is derived.

For a current CU having at least one non-zero MVD component, a first flag may be signaled to indicate whether the current CU uses quarter-luma sample MVD precision. If the first flag is 0 (e.g., corresponding to AMVR type=0 in table 1), no further signaling is required and the current CU uses quarter-luma sample MVD precision. In one example, the current CU is encoded using normal AMVP mode or affine AMVP mode. Otherwise, the first flag is not 0, and a second flag may be signaled to indicate whether the current CU (e.g., encoded in normal AMVP mode) uses half-luma sample MVD precision.

If the second flag is 0 (e.g., corresponding to AMVR type=3 in table 1), no further signaling is required and the current CU (e.g., encoded with normal AMVP mode) uses half-luma sample MVD precision. In some examples, an optional half-Pel Interpolation Filter (IF) is used in motion compensation. Otherwise, the second flag is not 0, and a third flag may be signaled for indicating whether the current CU, which is coded in normal AMVP mode, adopts 1-Pel (or integer luminance samples) (e.g., corresponding to AMVR type=1 in table 1) or 4-Pel (or four luminance samples) MVD precision (e.g., corresponding to AMVR type=2 in table 1).

The same second flag may be used to indicate whether the current CU encoded in affine AMVP mode employs integer luma samples or 1/16-Pel (or 1/16 luma samples) MVD precision (e.g., corresponding to AMVR type=1 in table 1).

To ensure that the reconstructed MVs may have the desired precision (e.g., quarter-luma samples (or 1/4-Pel), integer-luma samples (or 1-Pel), or four-luma samples (or 4-Pel)), the MV predictor(s) or MVP(s) of the CU may be rounded to the same precision as the corresponding MVD(s) before adding to the corresponding MVD(s). The MV predictor(s) may be rounded to zero (e.g., a negative MV predictor is rounded to tend to positive infinity, while a positive MV predictor is rounded to tend to negative infinity).

In some examples, the MVD precision of the encoded block, e.g., the AMVR type, may be signaled in the manner described below.

The flag (or AMVR flag, e.g., amvr_flag x0 y 0) may indicate the resolution (or MVD resolution or MVD precision) of the MVD of the encoded block. The array indices x0, y0 may indicate the position (x 0, y 0) of the upper left luma sample of the coding block relative to the upper left luma sample of the image comprising the coding block. An AMVR flag (e.g., amvr_flag [ x0] [ y0 ]) equal to 0 may indicate that the resolution of the MVD is 1/4 (or 1/4-Pel) of a luma sample, as shown in Table 2. An AMVR flag (e.g., amvr_flag [ x0] [ y0 ]) equal to 1 may indicate that the resolution of the MVD may be further indicated by a flag (or AMVR precision index, e.g., amvr_precision_idx [ x0] [ y0 ]).

When the AMVR flag (e.g., amvr_flag [ x0] [ y0 ]) is not present, the AMVR flag may be deduced as follows: (i) If CuPredMode [ chType ] [ x0] [ y0] is equal to MODE_IBC, indicating that the prediction MODE of the encoded block (e.g., cuPredMode [ chType ] [ x0] [ y0 ]) is IBC MODE (e.g., MODE_IBC), then an AMVR flag (e.g., amvr_flag [ x0] [ y0 ]) is equal to 1 can be inferred; (ii) Otherwise, cuPredMode [ chType ] [ x0] [ y0] is not equal to MODE_IBC, indicating that the prediction MODE of the encoded block is not IBC MODE, then an AMVR flag (e.g., amvr_flag [ x0] [ y0 ]) may be inferred to be equal to 0.

Referring to table 2, an amvr precision index (e.g., amvr_precision_idx [ x0] [ y0 ]) (e.g., equal to 0, 1, or 2) may indicate a resolution of the MVD and/or an offset (e.g., amvrShift) relative to a resolution of the MVD of the encoded block encoded with a prediction mode (e.g., IBC mode or IBC AMVP mode, affine AMVP mode, normal AMVP mode). As described above, the array indices x0, y0 may indicate the position (x 0, y 0) of the upper left luma sample of the encoded block relative to the upper left luma sample of the image.

When the AMVR precision index (e.g., amvr_precision_idx [ x0] [ y0 ]) does not exist, the AMVR precision index may be inferred to be equal to 0.

The MVD of the encoded block may be modified in the resolution of the MVD (e.g., amvrShift) as follows. For example, if inter_affine_flag [ x0] [ y0] is equal to 0, indicating that the prediction mode is not affine AMVP mode, the variables MvdL0[ x0] [ y0] [0], mvdL0[ x0] [ y0] [1], mvdL1[ x0] [ y0] [0], mvdL1[ x0] [ y0] [1] are modified as follows:

MvdL0[ x0] [ y0] [0] = MvdL0[ x0] [ y0] [0] < < AmvrShift (equation 3);

MvdL0[ x0] [ y0] [1] =MvdL 0[ x0] [ y0] [1] < < AmvrShift (equation 4);

MvdL1[ x0] [ y0] [0] =MvdL 1[ x0] [ y0] [0] < < AmvrShift (equation 5);

MvdL1[ x0] [ y0] [1] =MvdL 1[ x0] [ y0] [1] < < AmvrShift (equation 6);

wherein the variables MvdL0[ x0] [ y0] [0], mvdL0[ x0] [ y0] [1], mvdL1[ x0] [ y0] [0], mvdL1[ x0] [ y0] [1] may represent a horizontal component of the first MVD of the reference picture L0, a vertical component of the first MVD of the reference picture L0, a horizontal component of the second MVD of the reference picture L1, and a vertical component of the second MVD of the reference picture L1.

Otherwise, inter_affine_flag [ x0] [ y0] equals 1, for example, indicating that the prediction mode is affine AMVP mode, the variables MvdCpL0[ x0] [ y0] [0] [0], mvdCpL0[ x0] [ y0] [1] [0], mvdCpL0[ x0] [ y0] [1], mvdCpL0[ x0] [ y0] [2] [0] and MvdCpL0[ x0] [ y0] [2] [1] can be modified as follows:

MvdCpL0[ x0] [ y0] [0] [0] =mvdcpl 0[ x0] [ y0] [0] [0] < < AmvrShift (equation 7);

MvdCpL1[ x0] [ y0] [0] [1] =mvdcpl 1[ x0] [ y0] [0] [1] < < AmvrShift (equation 8);

MvcpL 0[ x0] [ y0] [1] [0] = MvcpL 0[ x0] [ y0] [1] [0] < < AmvrShift (equation 9);

MvcpL 1[ x0] [ y0] [1] [1] = MvcpL 1[ x0] [ y0] [1] [1] < < AmvrShift (equation 10);

MvcpL 0[ x0] [ y0] [2] [0] = MvcpL 0[ x0] [ y0] [2] [0] < < AmvrShift (equation 11);

MvcdCPL 1[ x0] [ y0] [2] [1] = MvcdCPL 1[ x0] [ y0] [2] [1] < < AmvrShift (equation 12);

wherein the variables MvcpL 0[ x0] [ y0] [0] [0], mvcpL 0[ x0] [ y0] [0] [1], mvcpL 0[ x0] [ y0] [1] [0], mvcpL 0[ x0] [ y0] [1] [1], mvcpL 0[ x0] [ y0] [2] [0] and MvcpL 0[ x0] [ y0] [2] [1] can represent a horizontal component of the first CP MVD, a vertical component of the first CP MVD, a horizontal component of the second CP MVD, a vertical component of the second CP MVD, and a horizontal component of the third CP MVD, a vertical component of the third CP MVD.

Table 2: examples of AmvrShift

Referring to table 2, offsets (e.g., AMVRSshift) 0 (no offset), 2 (e.g., offset by 2 bits), 3 (e.g., offset by 3 bits), 4 (e.g., offset by 4 bits), and 6 (e.g., offset by 6 bits) may correspond to MVD precision of 1/16-Pel (e.g., 1/16 luma samples), 1/4-Pel (e.g., 1/4 luma samples), 1/2-Pel (e.g., 1/2 luma samples), 1-Pel (e.g., 1 luma samples), and 4-Pel (e.g., 4 luma samples), respectively.

An optional half-Pel Interpolation Filter (IF) may be used in accordance with aspects of the present disclosure. In normal AMVP mode, when MVD accuracy (also referred to as AMVR accuracy) is signaled as 1/2-Pel or 1/2 luma samples of a block, an optional half-Pel IF may be used in motion compensation of the block. A half-Pel IF index or flag (e.g., hpelif idx) may be used to indicate whether an optional half-Pel IF is used. The value of the half-Pel IF index (e.g., hpelif idx) can be derived as follows:

hpelifhdx=amvrshift= =31: 0 (Eq.13)

Referring to Table 2, when an offset (e.g., amvrShift) of 3 indicates MVD precision of 1/2-Pel, then the value of the half-Pel IF index (e.g., hPelIfIdx) is 1. Otherwise, when the offset (e.g., amvrShift) is not 3, indicating that the MVD precision is not 1/2-Pel, then the value of the half-Pel IF index (e.g., hPelIfIdx) is 0. The half-Pel IF index (e.g., hPelIfIdx) may be inherited during inter-frame merging. The spatial inter CPMVP merge candidate (also referred to as spatial CPMVP merge candidate) may include a half-Pel IF index or flag (e.g., hpelif idx) along with other motion information (e.g., one or more MVs, reference pictures L0 and/or L1).

In one example, the inter-frame merge process includes a conventional merge mode, as well as other merge modes based on conventional merge candidates. In one example, the inter-frame merging process refers to an inter-frame merging mode. The inter-frame merging process may include a number of tools, such as spatial merging, temporal merging, and/or pairwise averaging (where two candidate uni-directional MVs are combined together), history-based MVP (HMVP), MMVD, and the like. In one example, during inter-frame merging, the merge flag is true (e.g., a value of 1).

In one example, at decoder size, when the MVD precision is 1/2-Pel precision, the decoder may set an internal flag (e.g., not signaled) to indicate the use of an optional half-Pel IF. In one example, the internal flag is not signaled in the grammar. The internal flags of the block may be stored. Thus, the internal markers may propagate. When combined with a spatial neighboring block (e.g., without signaling of MVDs), the internal flags may be inherited from the spatial neighboring block.

In some examples, the MVD precision or AMVR of the normal inter-frame AMVP mode includes a half-Pel precision (1/2-Pel), and when half-Pel precision is used (also referred to as AMVR half-Pel precision), an optional half-Pel IF is used. The flag may be utilized to indicate the use of an optional half-Pel IF (also referred to as a half-Pel IF flag, e.g., hpelif idx). In some examples, the half-Pel IF flag is inherited from one or more spatial neighbors, e.g., in an inter-frame merge mode (or inter-frame merge process). However, the half-Pel IF flag is not considered during the pruning process.

In some examples, the half-Pel IF flag is considered in the pruning process (e.g., CPMVP merge candidate pruning process). Accordingly, the CPMVP merge candidates may be pruned by taking the half-Pel IF flag into account. In the CPMVP combining candidate pruning, the use of an optional half-Pel IF may be considered.

An optional half-Pel IF flag (e.g., denoted hpelif idx) may be used with the motion information in a pruning process (e.g., CPMVP merge candidate pruning process).

In one embodiment, an optional half-Pel IF flag (e.g., denoted hpelif idx) is used in conjunction with motion information (e.g., including the reference picture used, one or more MVs, e.g., value(s) of MV(s), etc.) for comparison of CPMVP merge candidates (e.g., two CPMVP merge candidates) for pruning purposes. In one example, two CPMVP merge candidates are considered identical only when their motion information and the half-Pel IF flag (e.g., hpelif idx) values are identical, and thus one MV of the two CPMVP merge candidates may be pruned (e.g., removed from the merge candidate list).

In one example, the merge candidate list includes a first CPMVP merge candidate including first motion information and a first flag of a first neighboring block. The first flag may indicate whether the first neighboring block uses an optional half-Pel IF. The second CPMVP merge candidate includes second motion information of a second neighboring block and a second flag. The second flag may indicate whether the second neighboring block uses an optional half-Pel IF. The first CPMVP merge candidate and the second CPMVP merge candidate may be compared. In one example, when the first motion information and the second motion information are the same and the first flag is the same as the second flag, the first CPMVP merge candidate and the second CPMVP merge candidate are considered to be the same, and thus the second CPMVP merge candidate may not be added to the merge candidate list.

In some examples, the encoding information for the current block may be decoded from the encoded video bitstream. The codec information may include a pixel precision flag indicating whether the current block uses fractional pixel precision and a first filter flag indicating whether the current block uses an optional fractional pixel Interpolation Filter (IF). Hereinafter, the pixel precision flag and the filter flag may be simply referred to as the flag, but it should be understood that the flag indicating the pixel precision is the pixel precision flag and the flag indicating the IF used is the filter flag. The merge candidate list of the current block may include at least one CPMVP merge candidate. Each of the at least one CPMVP merge candidates may include motion information and a second filter flag. The motion information may include motion vectors of neighboring blocks of the current block and corresponding reference pictures. The second filter flag indicates whether the corresponding neighboring block of the current block uses the optional fractional pixel IF. Each of the at least one CPMVP merge candidates may be attributed to a corresponding neighboring block of the current block. The merge candidate list may be pruned based on motion information and a second filter flag associated with each CPMVP merge candidate. Samples in the current block may be reconstructed based on one CPMVP merge candidate of the at least one CPMVP merge candidates.

In some examples, the encoding information for the current block may be decoded from the encoded video bitstream. The coding information may indicate an inter merge mode (e.g., a normal AMVP mode) of the current block. The merge candidate list of the current block may include at least one CPMVP merge candidate. Each of the at least one CPMVP merge candidates may include motion information and a flag indicating whether a corresponding neighboring block of the current block uses an optional half-Pel IF. Each of the at least one CPMVP merge candidates may be attributed to a corresponding neighboring block of the current block. According to aspects of the present disclosure, the merge candidate list may be pruned based on motion information and flags associated with respective CPMVP merge candidates. In some examples, the CPMVP merge candidates include motion information and flags. Samples in the current block may be reconstructed based on one CPMVP merge candidate of the at least one CPMVP merge candidates. The motion information may include motion vectors of neighboring blocks of the current block and corresponding reference pictures.

In one example, the at least one CPMVP merge candidate includes a first candidate CPMVP and a second candidate CPMVP. The first candidate CPMVP includes first motion information (e.g., a first MV and a first reference picture L0) of a first neighboring block and a second filter flag of the first neighboring block. The second filter flag of the first neighboring block may indicate whether the first neighboring block uses an optional fractional pixel IF (e.g., half-Pel IF). The second candidate CPMVP includes second motion information (e.g., a second MV and a second reference picture L0) of a second neighboring block and a second filter flag of the second neighboring block. The second filter flag of the second neighboring block may indicate whether the second neighboring block uses an optional fractional pixel IF (e.g., half-Pel IF). The first neighboring block and the second neighboring block may be neighboring blocks of the current block.

One of the first candidate CPMVP and the second candidate CPMVP may be pruned based on the first motion information, the second filter flag of the first neighboring block, and the second filter flag of the second neighboring block.

The merge candidate list may be pruned based on the first motion information, the second filter flag of the first neighboring block, and the second filter flag of the second neighboring block.

In one example, whether the first candidate CPMVP is the same as the second candidate CPMVP may be determined based on the first motion information, the second filter flag of the first neighboring block, and the second filter flag of the second neighboring block. For example, when the first motion information is the same as the second motion information and the second filter flag of the first neighboring block is the same as the second filter flag of the second neighboring block, the first candidate CPMVP is determined to be the same as the second candidate CPMVP, and thus one of the first candidate CPMVP and the second candidate CPMVP may be pruned (e.g., removed from the merge candidate list).

In one example, the first motion information includes a first MV and a first reference picture (e.g., L0), and the second motion information includes a second MV and a second reference picture (e.g., L0). In one example, the first motion information includes a first MV (e.g., MV1 and MV 2) and a corresponding first reference picture (e.g., reference picture L0 of MV1 and reference picture L1 of MV 2), and the second motion information includes a second MV (e.g., MV3 and MV 4) and a corresponding second reference picture (e.g., reference picture L0 of MV3 and reference picture L1 of MV 4).

Any suitable signaling may be applied to the ambr codec. In one example, the encoded information for the block in the current picture may be decoded from the encoded video bitstream. The encoded information may include a flag or binary number (also referred to as half-Pel flag or half-Pel binary number) indicating whether the component of the MVD of the block uses half-Pel precision.

In some examples, variable length coding may be used, as shown in tables 3-6 above. In one example, the signaling order (or binarization) (also referred to as AMVR precision or MVD precision) of an AMVR for normal AMVP mode is shown in table 3 below.

TABLE 3 Table 3

Binary data conversion	AMVR precision
		0	1/4-Pel
10	1/2-Pel (with optional half-Pel IF)
		110	1-Pel
111	4-Pel

As shown in table 3, a first binary number or first flag may be used to encode whether 1/4-Pel precision is used for the block (e.g., a component of the MVD of the block), and a second binary number or second flag may be used to encode whether 1/2-Pel precision is used for the block. In one example, when using 1/2-Pel precision, an optional half-Pel IF is used for motion compensation of the block. A third binary number or a third flag may be used to code whether 1-Pel or 4-Pel precision is used for the block.

The signaling order or binarization of the MVD precision described above may be appropriately adjusted. In general, MVD precision may use any suitable signaling order to optimize codec efficiency and improve codec performance.

In some examples, the plurality of AMVR precision available for the component of the MVD for the block includes 1/4-Pel precision, 1/2-Pel precision, 1-Pel precision, and 4-Pel precision.

The half-Pel flag or half-Pel binary number indicating whether the block uses 1/2-Pel precision may be signaled after one or more flags indicating the use of one or more MVD precision. In one example, the half-Pel flag is signaled after a 1/4-Pel precision flag indicating whether 1/4-Pel precision is used, and after a 1-Pel precision flag indicating whether 1-Pel precision is used, as shown in tables 4-5. Table 4 shows an example of binarization of AMVR in normal AMVP mode.

Table 4 shows an example of binarization of MVD precision in normal AMVP mode.

Binarization of	AMVR precision
		0	1/4-Pel
10	1-Pel
		110	4-Pel
111	1/2-Pel (with optional half-Pel IF)

As shown in table 4, a first flag may be used to codec whether 1/4-Pel precision is used for the block (e.g., the component of the MVD of the block), and a second flag may be used to codec whether 1-Pel precision is used for the block. The third flag may be used to determine whether 1/2-Pel or 4-Pel precision is used for the coding of the block and may therefore be referred to as the half-Pel flag. In one example, when using 1/2-Pel precision, an optional half-Pel IF is used for motion compensation of the block.

Table 5 shows an example of binarization of AMVR in normal AMVP mode.

Table 5 shows an example of binarization of MVD precision in normal AMVP mode.

Binarization of	AMVR precision
		0	1/4-Pel
10	1-Pel
		110	1/2-Pel (with optional half-Pel IF)
111	4-Pel

As shown in table 5, a first flag may be used to codec whether 1/4-Pel precision is used for the block (e.g., the component of the MVD of the block), and a second flag may be used to codec whether 1-Pel precision is used for the block. The third flag may be used to determine whether 1/2-Pel or 4-Pel precision is used for the coding of the block and may therefore be referred to as the half-Pel flag. In one example, when using 1/2-Pel precision, an optional half-Pel IF is used for motion compensation of the block.

The binarization in tables 4 to 5 is similar, except that in Table 4, when the half-Pel flag is 1, 1/2-Pel accuracy is used. In Table 5, when the half-Pel flag is 0, 1/2-Pel precision is used. Comparing tables 3 to 5, the half-Pel flag is the third flag in tables 4 to 5, and the half-Pel flag is the second flag in table 3. Thus, if the frequency of use of 1/2-Pel accuracy is lower than 1-Pel accuracy and/or 4-Pel accuracy, the binary quantization schemes, e.g., in tables 4 and 5, may be used to improve codec efficiency.

In one embodiment, the flags indicating 1-Pel precision or 4-Pel precision may be modified as shown in Table 6. Table 6 shows an example of binarization of MVD precision in normal AMVP mode.

Table 6 shows an example of binarization of MVD precision in normal AMVP mode.

Binarization of	AMVR precision
		0	1/4-Pel
10	1/2-Pel (with optional half-Pel IF)
		110	4-Pel
111	1-Pel

Table 6 is similar to Table 3 except that the binarization for 4-Pel precision in Table 6 is 110,1-Pel precision is 111, while the binarization for 4-Pel precision in Table 3 is 111, and the binarization for 1-Pel precision is 110. Thus, a third flag of 0 in Table 3 indicates that 1-Pel precision is used, while a third flag of 0 in Table 6 indicates that 4-Pel precision is used.

Referring to table 6, before a third flag (also referred to as an integer flag) indicating whether 4-Pel precision or 1-Pel precision is used, a half-Pel flag (e.g., a second flag) indicating whether 1/2-Pel precision is used is signaled. A value of 0 for the third flag indicates that 4-Pel precision is used. A value of 1 for the third flag indicates that 1-Pel accuracy is used.

In some examples, fixed length coding may be used to codec multiple accuracies, as shown in table 7. Referring to table 7, two flags or binary numbers may be used to indicate binarization of MVD precision. The first flag or first binary number may be used to indicate whether a fractional-Pel resolution (also referred to as fractional-Pel precision) is used (e.g., 1/4-Pel or 1/2-Pel). The second flag or the second binary number after the first flag may indicate which fractional-Pel resolution is used if the first binary number indicates that fractional-Pel resolution is used, or may indicate which integer-Pel precision (also referred to as integer-Pel resolution) is used if the first binary number indicates that integer-Pel resolution is used. Table 7 shows an example of binarization of MVD precision in normal AMVP mode.

Table 7 shows an example of binarization of MVD precision in normal AMVP mode.

Binarization of	AMVR precision
		00	1/4-Pel
01	1/2-Pel (with optional half-Pel IF)
		10	1-Pel
11	4-Pel

As described above, the coding information of the block in the current picture may be decoded from the coded video bitstream. The coding information may include a half-Pel flag indicating whether a component of the MVD of the block uses half-Pel precision. The value of the half-Pel flag may be determined based on one of: (i) at least one of the first flag and the second flag; (ii) A temporal layer Identification (ID) of a current image in the temporal layer; and (iii) block size information for the block. The first flag may indicate whether the left neighbor block of the block uses an optional half-Pel IF and may therefore be referred to as the first hPelIfIdx (or first hPelIfIdx flag). The second flag may indicate whether an optional half-Pel IF is used for an upper neighbor of the block, and thus may be referred to as a second hPelIfIdx (or second hPelIfIdx flag). In response to the value of the flag indicating that the component of the MVD uses half-Pel precision, the MVs of the block may be determined using half-Pel precision. Furthermore, samples in the block may be reconstructed based on the MV. The left neighboring block may be adjacent to the block. The upper neighboring block may be adjacent to the block.

The above and following description uses the half-Pel flag to indicate whether the components of the MVD of the block use half-Pel precision as an example, but may also be applied to other MVD precision, such as 1/4-Pel precision, 1-Pel precision, and 4-Pel precision.

Context-adaptive binary arithmetic coding (CABAC) may be used to encode the half-Pel flag. In some examples, the half-Pel flag indicating whether to use AMVR half-Pel accuracy may be encoded with a single context model (also referred to as context, CABAC context model). In some examples, as described above, multiple context models are available in CABAC, and one of the multiple context models may be selected to codec the half-Pel flag, e.g., based on: (i) at least one of the first flag and the second flag; (ii) a temporal layer ID of the current image; and (iii) block size information for the block.

In some examples, one context model may be determined from a plurality of context models (e.g., two context models) of CABAC based on at least one of the first flag and the second flag. Further, the value of the flag may be determined using CABAC with the determined context model.

In some examples, one or more flags of the optional half-Pel IF may be used for context modeling in CABAC.

In one embodiment, a first hpelifhdx flag from a left neighboring block and/or a second hpelifhdx flag from an upper neighboring block is used to determine a context model for encoding and decoding a half-Pel flag that indicates whether AMVR half-Pel precision is used for the block (e.g., encoding or decoding).

In one example, when the value of the first hPelIfIdx is true (e.g., value 1) or the value of the second hPelIfIdx is true (e.g., value 1), one of the two context models is used to codec the half-Pel flag. Otherwise, if the values of both the first hPelIfIdx and the second hPelIfIdx are false (e.g., 0), then the other of the two context models is used to codec the half-Pel flag.

In one example, when both the value of the first hPelIfIdx and the value of the second hPelIfIdx are true, one of the two context models is used to codec the half-Pel flag. Otherwise, if the value of the first hPelIfIdx is false or the value of the second hPelIfIdx is false, the other of the two context models is used to codec the half-Pel flag.

In one embodiment, the half-Pel flag may be encoded using bypass codec mode without CABAC context.

The optional half-Pel IF flag or flags of the neighboring blocks of the block may be used to determine whether to use CABAC with context model or bypass codec mode to codec the half-Pel flag.

In one embodiment, the first hPelIfIdx flag of the left neighboring block and the second hPelIfIdx flag of the upper neighboring block are used to determine whether to use CABAC with at least one context model or bypass codec mode to codec the half-Pel flag.

In one example, when the value of the first hPelIfIdx flag is true or the value of the second hPelIfIdx flag is true, the half-Pel flag indicating the AMVR half-Pel accuracy is encoded using CABAC with at least one context model. Otherwise, if the values of the first hPelIfIdx flag and the second hPelIfIdx flag are both false, the half-Pel flag is encoded using the bypass codec mode.

In one example, when the value of the first hPelIfIdx flag is true and the value of the second hPelIfIdx flag is true, the half-Pel flag is encoded using CABAC with at least one context model. Otherwise, if the value of the first hPelIfIdx flag or the value of the second hPelIfIdx flag is false, the half-Pel flag is encoded using the bypass codec mode.

In general, whether to use a context model in CABAC may be determined based on at least one of the first flag (or the first hPelIfIdx flag) and the second flag (or the second hPelIfIdx flag) (e.g., at least one value of the first hPelIfIdx flag and the second hPelIfIdx flag). In response to using the context model, the value of the half-Pel flag may be determined using CABAC with the context model. The bypass codec mode may be used to determine the value of the half-Pel flag in response to not using the context model.

According to the present disclosure, a context model to be used in CABAC may be determined based on a temporal layer ID of a current image. The value of the half-Pel flag may be determined using CABAC with the determined context model.

In one example, the context model may be one of one or more context models in CABAC. The temporal layer ID may be one of one or more temporal layer IDs of one or more temporal layers allowed by the current image. The temporal layer ID may correspond to a context model.

The temporal layer ID of the current image may be used for context modeling.

In one embodiment, the value of the temporal layer ID of the current image may be used to derive a context model for encoding and decoding the half-Pel flag indicating whether AMVR half-Pel accuracy is used. When the current image allows multiple temporal layers, each of the multiple temporal layer IDs of the multiple temporal layers may correspond to a separate context model. For example, the context models 0, 1, and 2 may correspond to the plurality of temporal layers ID 0, 1, and 2, respectively. Accordingly, if the value of the temporal layer ID of the current image is 0, the context model 0 is selected to codec the half-Pel flag. If the value of the temporal layer ID of the current image is 1, the context model 1 is selected to encode and decode the half-Pel flag. If the value of the temporal layer ID of the current image is 2, the context model 2 is selected to encode and decode the half-Pel flag.

The context model may be determined from two context models in CABAC based on the temporal layer ID and a threshold (e.g., a threshold for the temporal layer ID).

In one embodiment, the value of the temporal layer ID of the current image may be used to derive a context model that encodes a half-Pel flag that indicates whether AMVR half-Pel precision is used. Two context models may be selected. The threshold of temporal layer ID may be used to determine which of the two context models to use. In one example, one of the two context models is used when the value of the temporal layer ID is less than or equal to a threshold. Otherwise, when the value of the time layer ID is greater than the threshold, the other one of the two context models is used. The threshold may be any suitable value. In one example, the threshold is set to 1. In one example, the threshold is set to 2.

The context model may be determined from the N context models in CABAC based on the temporal layer ID and the (N-1) threshold. N may be less than the maximum number of allowable temporal layers having a plurality of temporal layer IDs including the temporal layer ID.

In one embodiment, the value of the temporal layer ID of the current image may be used to derive a context model that encodes a half-Pel flag that indicates whether AMVR half-Pel precision is used. N context models may be selected. The (N-1) threshold may be used to examine the value of the temporal layer ID of the current image to determine which one of the N context models to use.

The block size information of the block may be used for context modeling.

The context model may be determined from two context models in CABAC based on block size information of the block and a threshold. The value of the half-Pel flag may be determined using CABAC with the determined context model. The block size information of the block may indicate at least one of: (i) width of block (or block width); (ii) the height of the block (or block height); and (iii) the number of luma samples in a block (or a region of a block).

In one embodiment, the values of block width and block height may be used to derive a context model to be used in CABAC having two context models for coding and decoding the half-Pel flag indicating whether AMVR half-Pel accuracy is used. When both the block width and the block height are greater than the threshold (or the value of the threshold), one of the two context models may be used. Otherwise, another one of the context models may be used. The threshold may be set to 32 luminance samples.

In one embodiment, the values of block width and block height may be used to derive a context model for encoding and decoding the half-Pel flag. When the block width or the block height is greater than the threshold, one of the two context models may be used. Otherwise, another one of the context models may be used.

In one embodiment, the number of luma samples in the block (or the area of the block) may be used to derive a context model for encoding and decoding the half-Pel flag. When the number of luminance samples in a block is greater than a threshold, one of two context models may be used. Otherwise, another one of the context models may be used. The threshold value may be set to any suitable value or any suitable luminance sample, for example 256 luminance samples, 1024 luminance samples, etc.

In some examples, a first filter flag in the encoded information of the block may indicate whether the block uses an optional 1/4-Pel IF. The samples in the block may be reconstructed based on the optional 1/4-Pel IF in response to the first filter flag of the encoded information indicating that the block uses the optional 1/4-Pel IF.

In some examples, the encoding information for the block may indicate whether the block uses 1/4-Pel precision and optionally 1/4-Pel IF. In response to the encoding information indicating that the block uses 1/4-Pel precision and optionally 1/4-Pel IF, the MV of the block may be determined using 1/4-Pel precision. Samples in the block may be reconstructed based on the MV and optionally the 1/4-Pel IF.

When using AMVR precision, a flag may be signaled to indicate whether an alternative interpolation filter for other MVD precision (e.g., quarter-Pel) motion compensation is used for the block.

An optional quarter-Pel IF may be used for quarter Pel motion compensation.

In one embodiment, when AMVR accuracy is used, a flag may be signaled to indicate whether an optional quarter-Pel IF is used for motion compensation of the block.

A flag may be signaled to indicate whether an optional 1/4-Pel IF is used for the block.

The encoded information may include a flag indicating whether an optional 1/4-Pel IF is used for the block.

The optional quarter Pel IF may have any suitable filter length or any suitable number of taps. In one example, the selectable quarter Pel IF is a 6 tap filter as shown below.

{0，0，128，0，0，0}，

{0，20，60，42，6，0}，

{-2，14，52，52，14，-2}，

{0，6，42，60，20，0}。

In one example, the selectable quarter Pel IF is a 4 tap filter as shown below.

{0，128，0，0}，

{20，60，42，6}，

{12，52，52，12}，

{6，42，60，20}。

The optional quarter Pel IF may be of any other type and is therefore not limited by the above examples.

In one embodiment, an optional quarter Pel IF is used, which may be indicated by a flag (e.g., a quarter Pel IF flag). The quarter Pel IF flag may be signaled or derived. For example, similar to the propagation of half-Pel IF flags, quarter Pel IF flags may propagate in merge mode.

The use of the optional 1/4-Pel IF may be determined based on the encoded information. The CPMVP merge candidates in the merge candidate list of neighboring blocks of the block may include a flag and the MV of the block, wherein the flag may indicate that an optional 1/4-Pel IF is used.

The encoded information may indicate the use of an alternative 1/4-Pel IF, for example, with a quarter Pel IF flag. The CPMVP merge candidates in the merge candidate list of neighboring blocks of the block may include a quarter Pel IF flag and the MV of the block.

For neighboring blocks of the block, the merge candidate list may be pruned based on the motion information and a flag indicating whether an optional 1/4-Pel IF is used for each CPMVP merge candidate of at least one CPMVP merge candidate in the merge candidate list, wherein the at least one CPMVP merge candidate includes the CPMVP merge candidate.

In one embodiment, when using an optional quarter Pel IF and propagating the quarter Pel IF flag in merge mode, the quarter Pel IF flag may be considered in the cpvp merge candidate pruning process, similar to the description above with respect to the half-Pel IF flag.

Fig. 12 shows a flowchart outlining a process (1200) according to an embodiment of the present disclosure. The process (1200) may be used for reconstruction of a block (e.g., CB) to generate a prediction block for the block under reconstruction. The term "block" may be interpreted as a prediction block, a Coding Block (CB), a Coding Unit (CU), etc. In various embodiments, process (1200) is performed by processing circuitry (e.g., processing circuitry in terminal devices (210), (220), (230), and (240), processing circuitry that performs the functions of video encoder (303), processing circuitry that performs the functions of video decoder (310), processing circuitry that performs the functions of video decoder (410), processing circuitry that performs the functions of video encoder (503), etc.). In some embodiments, the process (1200) is implemented by software instructions, so that when the processing circuitry executes the software instructions, the processing circuitry performs the process (1200). The process starts (S1201) and proceeds to (S1210).

At (S1210), the encoded information of the block may be decoded from the encoded video bitstream. The encoding information may indicate that the block is encoded and decoded in an inter-frame merge mode.

At (S1220), for the block, a merge candidate list including at least one CPMVP merge candidate may be pruned based on motion information and a flag associated with each of the at least one CPMVP merge candidates, as described above. Each CPMVP merge candidate of the at least one CPMVP merge candidate may be a neighboring block of the block. In some examples, the motion information and flags may be attributed to respective neighboring blocks of the block. The flag may indicate whether the corresponding neighboring block uses an optional half-Pel IF.

At (S1230), samples in the block may be reconstructed based on one CPMVP merge candidate of the at least one CPMVP merge candidate.

The process (1200) may be adapted for various scenarios and the steps in the process (1200) may be adjusted accordingly. One or more steps in process (1200) may be adjusted, omitted, repeated, and/or combined. The process (1200) may be implemented using any suitable order. Additional step(s) may be added.

Fig. 13 shows an overview flowchart of a process (1300) of an embodiment of the present disclosure. The process (1300) may be used in the reconstruction of a block (e.g., CB) to generate a prediction block for the block under reconstruction. The term "block" may be interpreted as a prediction block, a Coding Block (CB), a Coding Unit (CU), etc. In various embodiments, process (1300) is performed by processing circuitry (e.g., processing circuitry in terminal devices (210), (220), (230), and (240), processing circuitry that performs the functions of video encoder (303), processing circuitry that performs the functions of video decoder (310), processing circuitry that performs the functions of video decoder (410), processing circuitry that performs the functions of video encoder (503), etc.). In some embodiments, the process (1300) is implemented by software instructions, so that when the processing circuit executes the software instructions, the processing circuit executes the process (1300). The process starts (S1301) and proceeds to (S1310).

At (S1310), the encoded information of the block may be decoded from the encoded video bitstream. The coding information may include a flag indicating whether the component of the MVD of the block uses half-Pel precision.

At (S1320), the value of the flag may be determined based on one of: (i) At least one of the first flag and the second flag, (ii) a temporal layer ID of a current image in the temporal layer; and (iii) block size information for the block, as described above. The first flag may indicate whether the left neighbor block of the block uses an optional half-Pel IF and the second flag may indicate whether the upper neighbor block of the block uses an optional half-Pel IF.

At (S1330), a value of a flag indicating whether the component of the MVD uses half-Pel accuracy may be determined. In response to the value of the flag indicating that the component of the MVD uses half-Pel precision, the process (1300) proceeds to (S1340). Otherwise, the process (1300) proceeds to (S1360).

At (S1340), the MV of the block may be determined using half-Pel accuracy. The process (1300) proceeds to (S1350).

At (S1350), samples in the block may be reconstructed based on the MV. The process (1300) proceeds to (S1399), and terminates.

At (S1360), the MVD precision of the block may be determined, for example, by parsing additional markers signaled after the marker. The MVD precision may be 1-Pel precision, 4-Pel precision, etc. The process (1300) proceeds to (S1370).

At (S1370), samples in the block may be reconstructed based on the MVD precision. The process (1300) proceeds to (S1399), and terminates.

The process (1300) can be adapted to a variety of scenarios, and the steps in the process (1300) can be adjusted accordingly. One or more steps in the process (1300) may be adjusted, omitted, repeated, and/or combined. The process (1300) may be implemented using any suitable order. Additional step(s) may be added.

Fig. 14 shows a flowchart outlining a process (1400) according to an embodiment of the present disclosure. The process (1400) may be used for reconstruction of a block (e.g., CB) to generate a prediction block for the block under reconstruction. The term "block" may be interpreted as a prediction block, a Coding Block (CB), a Coding Unit (CU), etc. In various embodiments, process (1400) is performed by processing circuitry (e.g., processing circuitry in terminal devices (210), (220), (230), and (240), processing circuitry that performs the functions of video encoder (303), processing circuitry that performs the functions of video decoder (310), processing circuitry that performs the functions of video decoder (410), processing circuitry that performs the functions of video encoder (503), etc.). In some embodiments, the process (1400) is implemented by software instructions, so that when the processing circuitry executes the software instructions, the processing circuitry performs the process (1400). The process starts (S1401) and proceeds to (S1410).

At (S1410), the encoded information of the block may be decoded from the encoded video bitstream. As described above, the encoding information may indicate whether the block uses an optional 1/4-Pel IF. In some examples, the encoded information indicates whether the block uses 1/4-Pel precision, as described above.

At (S1420), when the encoding information indicates that the block uses an optional 1/4-Pel IF, samples in the block may be reconstructed based on the optional 1/4-Pel IF.

The process (1400) may be applicable to a variety of scenarios, and the steps in the process (1400) may be adjusted accordingly. One or more steps in process (1400) may be adjusted, omitted, repeated, and/or combined. The process (1400) may be implemented using any suitable order. Additional step(s) may be added.

In one example, the MVD precision may be determined when the encoded information indicates that the block does not use 1/4-Pel precision and optionally 1/4-Pel IF. The MVD precision may be used to determine the MVs of the block.

The embodiments in this disclosure may be used alone or in combination in any order. Furthermore, each of the methods, encoders, and decoders may be implemented by a processing circuit (e.g., one or more processors or one or more integrated circuits). In one example, one or more processors execute a program stored in a non-transitory computer readable medium.

The techniques described above may be implemented as computer software using computer readable instructions and physically stored in one or more computer readable media. For example, FIG. 15 is a computer system (1500) suitable for implementing some embodiments of the present application.

The computer software may be encoded with any suitable machine code or computer language, and the instruction code may be generated using assembly, compilation, linking, or similar mechanisms. These instruction codes may be executed directly by one or more computer Central Processing Units (CPUs), graphics Processing Units (GPUs), etc., or through operations such as code interpretation, microcode execution, etc.

These instructions may be executed in various types of computers or computer components, including, for example, personal computers, tablet computers, servers, smart phones, gaming devices, internet of things devices, and the like.

The components shown in fig. 15 for computer system (1500) are exemplary in nature and are not intended to limit the scope of use or functionality of computer software implementing embodiments of the present application. Nor should the arrangement of components be construed as having any dependency or requirement relating to any one or combination of components of the exemplary embodiment of the computer system (1500).

The computer system (1500) may include some human interface input devices. Such a human interface input device may be responsive to input by one or more human users through, for example, tactile input (e.g., key strokes, swipes, data glove movements), audio input (e.g., voice, swipes), visual input (e.g., gestures), olfactory input (not shown). The human interface device may also be used to capture certain media that are not necessarily directly related to human conscious input, such as audio (e.g., speech, music, ambient sound), images (e.g., scanned images, photographic images obtained from still image cameras), video (e.g., two-dimensional video, three-dimensional video including stereoscopic video).

The human interface input device may include one or more of the following (each depicting only one): a keyboard (1501), a mouse (1502), a touch pad (1503), a touch screen (1510), data gloves (not shown), a joystick (1505), a microphone (1506), a scanner (1507), a camera (1508).

The computer system (1500) may also include certain human interface output devices. Such human interface output devices may stimulate the sensation of one or more human users by, for example, tactile output, sound, light, and smell/taste. Such human-machine interface output devices may include haptic output devices (e.g., haptic feedback via a touch screen (1510), a data glove (not shown), or a joystick (1505), but there may be haptic feedback devices that do not serve as input devices), audio output devices (e.g., speakers (1509), headphones (not shown)), visual output devices such as a screen (1510), virtual reality glasses (not shown), holographic displays, and smoke boxes (not shown), and printers (not shown), with the screen (1310) 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 haptic feedback capabilities, some of which are capable of outputting two-dimensional visual output or more than three-dimensional output by means such as stereoscopic image output.

The computer system (1500) may also include human-accessible storage devices and their associated media, such as optical media (including CD/DVD ROM/RW (1520) with CD/DVD) or similar media (1521), thumb drive (1522), removable hard drive or solid state drive (1523), traditional magnetic media (e.g., magnetic tape and floppy disk (not shown)), special ROM/ASIC/PLD based devices (e.g., secure dongle (not shown)), and the like.

It should also be appreciated by those skilled in the art that the term "computer-readable medium" as used in connection with the presently disclosed subject matter does not include transmission media, carrier waves or other transitory signals.

The computer system (1500) may also include an interface to connect to one or more communication networks. The network may be, for example, a wireless network, a wired network, an optical network. The network may also be a local network, wide area network, metropolitan area network, internet of vehicles and industrial network, real-time network, delay tolerant network, and the like. Examples of networks include local area networks (e.g., ethernet, wireless LAN), cellular networks (including global system for mobile communications (GSM), third generation mobile communications system (3G), fourth generation mobile communications system (4G), fifth generation mobile communications system (5G), long Term Evolution (LTE), etc.), television cable or wireless wide area digital networks (including cable television, satellite television, and terrestrial broadcast television), vehicle and industrial networks (including CANBus), and the like. Some networks typically require an external network interface adapter that connects to some general purpose data port or peripheral bus (1549) (e.g., a Universal Serial Bus (USB) port of a computer system (1500); other interfaces are typically integrated into the core of the computer system (1500) by connecting to a system bus as described below (e.g., into an ethernet interface of a personal computer system or into a cellular network interface of a smartphone computer system). Using any of these networks, the computer system (1500) may communicate with other entities. Such communications may be uni-directional, receive-only (e.g., broadcast TV), uni-directional transmit-only (e.g., CAN bus to some CAN bus device), or bi-directional communications to other computer systems using a local or wide area digital network. Certain protocols and protocol stacks may be used on each of those networks and network interfaces as described above.

The human interface device, human accessible storage device, and network interface described above may be connected to a kernel (1540) of the computer system (1500).

The kernel (1540) may include one or more Central Processing Units (CPUs) (1541), graphics Processing Units (GPUs) (1542), dedicated programmable processing units in the form of Field Programmable Gate Arrays (FPGAs) (1543), hardware accelerators (1544) for specific tasks, and the like. These devices, as well as Read Only Memory (ROM) (1545), random access memory (1546), internal mass storage (e.g., internal non-user accessible hard disk drive, SSD) (1547), etc., may be interconnected via a system bus (1548). In some computer systems, the system bus (1548) may be accessed in the form of one or more physical plugs to enable expansion by an additional CPU, GPU, or the like. Peripheral devices may be connected to the system bus (1549) of the core either directly or through a peripheral bus (1548). The architecture of the peripheral bus includes PCI, USB, etc.

The CPU (1541), GPU (1542), FPGA (1543) and accelerator (1544) may execute certain instructions that, in combination, may constitute the aforementioned computer code. The computer code may be stored in ROM (1545) or RAM (1546). Intermediate data may also be stored in RAM (1546), while persistent data may be stored in, for example, internal mass storage (1547). Fast storage and reading to any memory device may be achieved through the use of a cache memory, which may be closely associated with one or more CPUs (1541), GPUs (1542), mass storage (1547), ROMs (1545), RAMs (1546), and the like.

The computer readable medium may have computer code thereon, upon which various computer-executed operations are performed. The media and computer code may be those specially designed and constructed for the purposes of the present application, or they may be of the kind well known and available to those having skill in the computer software arts.

By way of example, and not limitation, a computer system having an architecture (1500), and in particular a kernel (1540), may provide functionality implemented by a processor (including CPU, GPU, FPGA, accelerators, etc.) executing software in one or more tangible computer-readable media. Such computer readable media may be media associated with user accessible mass storage as described above, as well as some storage of the non-transitory kernel (1540), such as the kernel internal mass storage (1547) or ROM (1545). Software implementing embodiments of the present application may be stored in such devices and executed by the kernel (1540). The computer-readable medium may include one or more memory devices or chips, according to particular needs. The software may cause the kernel (1540), particularly a processor therein (including CPU, GPU, FPGA, etc.), to perform certain processes or certain portions of certain processes described herein, including defining data structures stored in RAM (1546), and modifying those data structures according to the software defined processes. Additionally or alternatively, the computer system may provide the same functionality as logical hardwired or other components in the circuit (e.g., accelerator 1544), may operate in place of or in conjunction with software to perform certain processes or certain portions of certain processes described herein. References to software may include logic, and vice versa, where appropriate. References to computer readable medium may include circuitry (e.g., an Integrated Circuit (IC)) storing executable software, circuitry including executable logic, or both, where appropriate. This application includes any suitable combination of hardware and software.

Appendix a: abbreviations

JEM joint exploration model joint exploration model

VVC versatile video coding multifunctional video coding

BMS benchmark set reference set

MV Motion Vector

HEVC High Efficiency Video Coding high efficiency video coding

SEI Supplementary Enhancement Information supplemental enhancement information

VUI Video Usability Information video availability information

GOPs Group of Pictures image group

TUs Transform Units

PUs Prediction Units

CTUs Coding Tree Units coding tree units

CTBs Coding Tree Blocks coding tree blocks

PBs Prediction Blocks prediction block

HRD Hypothetical Reference Decoder hypothetical reference decoder

SNR Signal Noise Ratio SNR

CPU Central Processing Units central processing unit

GPUs Graphics Processing Units graphic processing unit

CRT (Cathode Ray Tube)

LCD (Liquid Crystal Display) Liquid Crystal Display

OLED (Organic Light-Emitting Diode)

Compact Disc

DVD Digital Video Disc digital video disc

ROM Read-Only Memory

RAM Random Access Memory RAM

ASIC Application-Specific Integrated Circuit Application specific integrated circuit

PLD Programmable Logic Device programmable logic device

LAN Local Area Network local area network

Global system for mobile communication (GSM) Global System for Mobile communications

LTE Long Term Evolution of Long-Term Evolution

CANBus Controller Area Network Bus controller area network bus

Universal Serial Bus (USB) Universal Serial Bus

PCI Peripheral Component Interconnect peripheral component interconnect

FPGA Field Programmable Gate Array field programmable gate array

SSD solid state disk

IC Integrated Circuit integrated circuit

CU Coding Unit

Advanced motion vector prediction for AMVP advanced motion vector prediction

HMVP History-based MVP History-based motion vector prediction

MMVD Merge with MVD Merge mode with motion vector difference

MVD Motion vector difference motion vector difference

MVP Motion vector predictor motion vector predictor

SbTMVP sub-based TMVP sub-block based temporal motion vector prediction

TMVP: temporal MVP Temporal motion vector prediction

VTM Versatile test model multifunctional test model

While this application has described a number of exemplary embodiments, various alterations, permutations, and various substitutions of embodiments are within the scope of this application. It will thus be appreciated that those skilled in the art will be able to devise various arrangements and methods which, although not explicitly shown or described herein, embody the principles of the application and are thus within its spirit and scope.

Claims (19)

1. A video decoding method, comprising:

decoding coding information of a current block from an encoded video bitstream, the coding information indicating that the current block is encoded in an inter-frame merge mode, the coding information including at least one pixel precision flag for indicating whether the current block uses fractional pixel precision and/or a first filter flag for indicating whether the current block uses an optional fractional pixel interpolation filter IF (Interpolation Filter);

for the current block, pruning a merge candidate list comprising at least one control point motion vector prediction CPMVP (Control Point Motion Vector Prediction) merge candidate, the pruning based on: deleting one of the two CPMVP merge candidates when motion information associated with the two CPMVP merge candidates and a second filter flag are identical, each CPMVP merge candidate of the at least one CPMVP merge candidate being one neighboring block of the current block, the second filter flag indicating whether the corresponding neighboring block uses an optional fractional-pixel interpolation filter IF;

Reconstructing samples in the current block based on one CPMVP merge candidate of the at least one CPMVP merge candidates.

2. The method of claim 1, wherein the step of determining the position of the substrate comprises,

the at least one CPMVP merge candidate includes a first candidate CPMVP including first motion information and a second filter flag of a first neighboring block and a second candidate CPMVP including second motion information and a second filter flag of a second neighboring block, the first neighboring block and the second neighboring block being neighboring blocks of the current block, the second filter flag of the first neighboring block and the second filter flag of the second neighboring block indicating whether the respective first neighboring block and second neighboring block use a selectable fractional pixel IF;

pruning the merge candidate list includes: and deleting one of the first candidate CPMVP and the second candidate CPMVP when the first motion information is the same as the second motion information and the second filter flag of the first neighboring block is the same as the second filter flag of the second neighboring block.

3. The method of claim 1, wherein the step of determining the position of the substrate comprises,

the motion information includes motion vectors of the neighboring blocks of the current block and corresponding reference images.

4. The method according to claim 1, characterized in that it comprises:

determining a value of the pixel precision flag based on one of: (i) at least one of the first flag and the second flag; (ii) a temporal layer identification, ID, of a current image in the temporal layer; and (iii) block size information of the current block, wherein the first flag indicates whether a left neighboring block of the current block uses an optional half-pixel precision interpolation filter half-Pel IF, and the second flag indicates whether an upper neighboring block of the current block uses an optional half-Pel IF;

the component of the motion vector difference MVD is used with half-Pel precision in response to the value of the pixel precision flag,

determining a Motion Vector (MV) of the current block using half-Pel precision, and

samples in the current block are reconstructed based on the MVs.

5. The method of claim 4, wherein determining the value of the pixel precision flag further comprises:

determining a context model from a plurality of context models in context-adaptive binary arithmetic coding, CABAC (context-adaptive binary arithmetic coding) based on at least one of the first flag and the second flag;

A value of the pixel precision flag is determined using CABAC with the determined context model.

6. The method of claim 4, wherein determining the value of the pixel precision flag further comprises:

determining whether to use a context model in CABAC based on at least one of the first flag and the second flag;

responsive to determining to use a context model, determining a value of the pixel precision flag using CABAC with the context model;

the value of the pixel precision flag is determined using a bypass codec mode in response to determining not to use the context model.

7. The method of claim 4, wherein determining the value of the pixel precision flag further comprises:

determining a context model to be used in CABAC based on a temporal layer ID of the current image;

a value of the pixel precision flag is determined using CABAC with the determined context model.

8. The method of claim 7, wherein the step of determining the position of the probe is performed,

the context model is one of one or more context models in CABAC;

the temporal layer ID is one of one or more temporal layer IDs of a corresponding one or more temporal layers allowed by the current image, the temporal layer ID corresponding to the determined context model.

9. The method of claim 7, wherein determining the context model further comprises:

the context model is determined from two context models in the CABAC based on the temporal layer ID and a threshold.

10. The method of claim 7, wherein determining the context model further comprises:

the context model is determined from N context models in the CABAC based on the temporal layer ID and (N-1) thresholds, N being less than an allowable maximum number of temporal layers having a plurality of temporal layer IDs including the temporal layer ID.

11. The method of claim 4, wherein determining the value of the pixel precision flag further comprises:

determining the context model from two context models of CABAC based on the block size information of the current block and a threshold;

a value of the pixel precision flag is determined using CABAC with the determined context model.

12. The method of claim 11, wherein the block size information of the current block indicates at least one of: (i) a width of the current block; (ii) a height of the current block; and (iii) the number of luma samples in the current block.

13. The method of claim 4, wherein the step of determining the position of the first electrode is performed,

the plurality of accuracies available for the component of the MVD of the current block include a 1/4-Pel accuracy, a 1/2-Pel accuracy, a 1-Pel accuracy, and a 4-Pel accuracy, the fractional pixel accuracy includes a 1/4-Pel accuracy and/or a 1/2-Pel accuracy, and the pixel accuracy flag includes a flag indicating whether to use the 1/2-Pel accuracy and a flag indicating whether to use the 1/4-Pel accuracy;

a flag indicating whether 1/2-Pel precision is used is signaled after a flag indicating whether 1-Pel precision is used and after a flag indicating whether 1/4-Pel precision is used;

wherein 1/4-Pel precision represents one quarter pixel precision; 1/2-Pel precision represents one-half pixel precision; 1-Pel represents 1 pixel precision; the 4-Pel precision represents a 4-pixel precision.

14. The method of claim 4, wherein the step of determining the position of the first electrode is performed,

the plurality of accuracies available for the component of the MVD of the current block include a 1/4-Pel accuracy, a 1/2-Pel accuracy, a 1-Pel accuracy, and a 4-Pel accuracy, the fractional pixel accuracy includes a 1/4-Pel accuracy and/or a 1/2-Pel accuracy, and the pixel accuracy flag includes a flag indicating whether to use the 1/2-Pel accuracy and a flag indicating whether to use the 1/4-Pel accuracy;

A flag indicating whether 1/2-Pel precision is used is signaled before a flag indicating whether 4-Pel precision or 1-Pel precision is used;

the value of the flag indicating whether 4-Pel precision or 1-Pel precision is used is 0, indicating that 4-Pel precision is used;

the value of the flag indicating whether 4-Pel precision or 1-Pel precision is used is 1, indicating that 1-Pel precision is used.

15. The method of claim 4, wherein the step of determining the position of the first electrode is performed,

the plurality of accuracies available for the component of the MVD of the current block includes a 1/4-Pel accuracy, a 1/2-Pel accuracy, a 1-Pel accuracy, and a 4-Pel accuracy;

the plurality of accuracies are encoded using a fixed-length code having a first binary number indicating whether the fractional pixel accuracy is used and a second binary number indicating the fractional pixel accuracy used.

16. The method according to claim 1, characterized in that it comprises:

responsive to the first filter flag in the encoded information indicating that the current block uses an optional 1/4-Pel IF, samples in the current block are reconstructed based on the optional 1/4-Pel IF.

17. The method of claim 16, wherein the step of determining the position of the probe comprises,

a first filter flag in the encoded information indicates whether the current block uses an optional 1/4-Pel IF.

18. A computing device comprising at least one processor and memory, wherein the memory has stored therein computer readable instructions that are executed by the at least one processor to implement the video decoding method of any of claims 1-17.

19. A computer readable storage medium storing computer readable instructions, wherein the instructions are executed by a processor to implement the video decoding method of any one of claims 1-17.

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