Method and apparatus for decoding using unified position dependent prediction combination process, and computer program

Abstract

To provide methods and apparatuses for video encoding / decoding.SOLUTION: An apparatus for video decoding includes processing circuitry that decodes prediction information for a current block in a current picture that is a part of a coded video sequence. The prediction information indicates an intra prediction direction for the current block that is one of (i) a diagonal intra prediction direction or (ii) a neighboring intra prediction direction adjacent to the diagonal intra prediction direction. The processing circuitry determines a usage of a position dependent prediction combination (PDPC) process according to the intra prediction direction of the current block. The same PDPC process is applied to both the diagonal intra prediction direction and the neighboring intra prediction direction. The processing circuitry reconstructs the current block based on the usage of the PDPC process on the current block.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] Incorporation by Reference This application claims the benefit of U.S. Patent Application No. 15 / 931,225, entitled "Integrated Location-Dependent Prediction Combination Process," filed May 13, 2020. This application claims the benefit of priority to U.S. Provisional Application No. 62 / 859,920, entitled "Integrated Location-Dependent Prediction Combination Process," filed June 11, 2019, and U.S. Provisional Application No. 62 / 869,015, entitled "Further Integration for a Location-Dependent Prediction Combination Process," filed June 30, 2019. The entire disclosures of these earlier applications are hereby incorporated by reference in their entireties.

[0002] Technical Field This disclosure describes embodiments generally related to video encoding. [Background technology]

[0003] The background discussion provided herein is intended to generally present the context of the present disclosure. Work of the inventors named in this application, to the extent that their work is described in this background section, and aspects of this description that may not otherwise qualify as prior art at the time of filing, are not admitted, either explicitly or implicitly, as prior art to the present disclosure.

[0004] Video encoding and decoding can be performed using inter-picture prediction with motion compensation. Uncompressed digital video can include a sequence of pictures, each having spatial dimensions of, for example, 1920x1080 luminance samples and associated chrominance samples. The sequence of pictures can have a fixed or variable picture rate (also informally known as frame rate), for example, 60 pictures per second or 60 Hz. Uncompressed video has significant bitrate requirements. For example, 1080p60 4:2:0 video (1920x1080 luminance sample resolution at a frame rate of 60 Hz) with 8 bits per sample requires a bandwidth approaching 1.5 Gbit / s. One hour of such video requires more than 600 Gbytes of storage space.

[0005] One goal of video encoding and decoding may be the reduction of redundancy in the input video signal through compression. Compression may help reduce the aforementioned bandwidth or storage space requirements, in some cases by more than one order of magnitude. Both lossless and lossy compression, as well as combinations thereof, may be used. Lossless compression refers to techniques where an exact copy of the original signal can be reconstructed from the compressed original signal. When lossy compression is used, the reconstructed signal may not be identical to the original signal, but the distortion between the original and reconstructed signals is small enough to make the reconstructed signal useful for the intended application. For video, lossy compression is widely used. The amount of acceptable distortion depends on the application, for example, users of certain consumer streaming applications may tolerate higher distortion than users of television distribution applications. The achievable compression ratio may reflect that a higher tolerable / acceptable distortion can result in a higher compression ratio.

[0006] Video encoders and decoders may utilize techniques from several broad categories, including motion compensation, transform, quantization, and entropy coding.

[0007] Video codec techniques can include a technique known as intra-coding. In intra-coding, sample values ​​are represented without reference to samples or other data from a previously reconstructed reference picture. In some video codecs, a picture is spatially divided into blocks of samples. If all blocks of samples are coded in intra mode, the picture may be an intra picture. Intra pictures and their derivatives, such as independent decoder refresh pictures, can be used to reset the decoder state and thus can be used as the first picture in a coded video bitstream and video session or as a still image. Samples of an intra block may be subjected to a transform, and the transform coefficients may be quantized before entropy coding. Intra prediction may be a technique that minimizes sample values ​​in the pre-transform domain. In some cases, the smaller the DC value and the smaller the AC coefficients after the transform, the fewer bits are required for a given quantization step size to represent the block after entropy coding.

[0008] Traditional intra-coding, as known for example from MPEG-2 generation coding techniques, does not use intra-prediction. However, some newer video compression techniques include techniques that attempt to do so from surrounding sample data and / or metadata obtained during encoding / decoding of blocks of data that are spatially neighbors and preceding in decoding order. Such techniques are referred to below as "intra-prediction" techniques. It should be noted that, at least in some cases, intra-prediction uses only reference data from the current picture being reconstructed and not from reference pictures.

[0009] There may be various forms of intra prediction. If more than one such technique is available for a given video coding technique, the technique used may be coded in an intra prediction mode. In some cases, a mode may have sub-modes and / or parameters, which may be coded separately or may be included in the mode codeword. Which codeword to use for a given mode / sub-mode / parameter combination may affect the coding efficiency gain through intra prediction, as well as the entropy coding technique used to convert the codeword into a bitstream.

[0010] Certain modes of intra prediction were introduced in H.264, refined in H.265, and further refined in newer coding techniques such as the Joint Exploration Model (JEM), Versatile Video Coding (VVC), and Benchmark Set (BMS). A predictor block can be formed using neighboring sample values ​​belonging to already available samples. The sample values ​​of the neighboring samples are copied to the predictor block according to a certain direction. The reference to the direction used can be coded in the bitstream or may itself be predicted.

[0011] Referring to FIG. 1A, at the bottom right, a subset of 9 known predictor directions from the 33 possible predictor directions (corresponding to the 33 angle modes of the 35 intra modes) of H.265 is depicted. The point (101) where the arrows converge represents the sample to be predicted. The arrows represent the direction in which the sample is predicted. For example, arrow (102) indicates that sample (101) is predicted from the sample(s) to the top right and at an angle of 45 degrees from the horizontal. Similarly, arrow (103) indicates that sample (101) is predicted from the sample(s) to the bottom left of sample (101), at an angle of 22.5 degrees from the horizontal.

[0012] Continuing to refer to FIG. 1A, at the top left, a square block (104) of 4×4 samples is depicted (indicated by a thick dashed line). The square block (104) contains 16 samples, each labeled with an “S” and its position in the Y dimension (e.g., row index) and its position in the X dimension (e.g., column index). For example, sample S21 is the second sample (from the top) in the Y dimension and the first sample (from the left) in the X dimension. Similarly, sample S44 is the fourth sample in the block (104) in both the Y and X dimensions. Since the block is 4×4 samples in size, S44 is at the bottom right. Additionally, a reference sample is shown that follows a similar numbering scheme. The reference sample is labeled with R and its Y position (e.g., row index) and X position (column index) relative to the block (104). In both H.264 and H.265, the predicted samples are neighbors of the block being reconstructed, so there is no need to use negative values.

[0013] Intra-picture prediction can work by copying reference sample values ​​from neighboring samples that are filled by the signaled prediction direction. For example, assume that the coded video bitstream includes signaling for this block that indicates a prediction direction that is consistent with the arrow (102). That is, the sample is predicted from the top right prediction sample(s) at an angle of 45 degrees from the horizontal. In that case, samples S41, S32, S23, and S14 are predicted from the same reference sample R05. Sample S44 is then predicted from reference sample R08.

[0014] In some cases, particularly when the orientation is not divisible by 45 degrees, the values ​​of multiple reference samples may be combined, for example by interpolation, to calculate the reference sample.

[0015] As video coding technology develops, the number of possible directions has increased. In H.264 (2003), nine different directions could be represented. This increased to 33 in H.265 (2013), and JEM / VVC / BMS at the time of this disclosure can support up to 65 directions. Experiments are performed to identify the most likely directions, and certain techniques in entropy coding are used to represent those likely directions with a small number of bits while accepting some penalty for the less likely directions. Furthermore, the direction itself may be predictable from nearby directions used in nearby already decoded blocks.

[0016] FIG. 1B shows a schematic diagram (105) depicting 65 intra prediction directions with JEM to illustrate the increasing number of prediction directions over time.

[0017] The mapping of intra-prediction direction bits in the coded video bitstream to represent directions can vary from one video coding technique to another, ranging from a simple direct mapping of prediction directions to intra-prediction modes, to complex adaptation schemes involving codewords, most probable modes, and similar techniques. In any case, however, there may be certain directions that are statistically less likely to occur in the video content than certain other directions. Because the goal of video compression is to reduce redundancy, in a well-performing video coding technique, these less likely ways are represented by more bits than the more likely directions.

[0018] Motion compensation may be a lossy compression technique and may refer to a technique used for the prediction of a newly reconstructed picture or part thereof after blocks of sample data from a previously reconstructed picture or part thereof (reference picture) are spatially shifted in a direction indicated by a motion vector (hereafter MV). In some cases, the reference picture may be the same as the picture currently being reconstructed. The MV may have two dimensions, X and Y, or three dimensions, with the third dimension being an indication of the reference picture used (which may indirectly be the temporal dimension).

[0019] In some video compression techniques, the MV applicable to a region of sample data can be predicted from other MVs, for example from an MV associated with another region of sample data that is spatially adjacent to the region being reconstructed and precedes it in decoding order. By doing so, the amount of data required to encode the MV can be significantly reduced, thereby removing redundancy and increasing compression. MV prediction can work in a directed manner because, for example, when encoding an input video signal derived from a camera (known as natural video), there is a statistical probability that regions larger than the region to which a single MV is applicable move in a similar direction and can therefore, in some cases, be predicted using similar motion vectors derived from the MVs of nearby regions. As a result, the MV found for a given region will be similar or identical to the MV predicted from the surrounding MVs, which, after entropy encoding, can be represented with fewer bits than would be used to directly encode the MVs. In some cases, MV prediction can be an example of lossless compression of a signal (i.e., an MV) derived from the original signal (i.e., a sample stream). In other cases, the MV prediction itself may be irreversible, for example due to rounding errors in computing the predictor from several surrounding MVs.

[0020] Various MV prediction mechanisms are described in H.265 / HEVC (ITU-T Rec. H.265, "High Efficiency Video Coding", December 2016). Among the many MV prediction mechanisms provided by H.265, a technique hereafter referred to as "spatial merge" is described herein.

[0021] Referring to Figure 1C, the current block (101) may contain samples that the encoder found during the motion search process to be predictable from a spatially shifted previous block of the same size. Instead of directly encoding its MV, the MV can be derived from metadata associated with one or more reference pictures, for example, from the most recent reference picture (in decoding order), using the MV associated with any of the five surrounding samples, denoted A0, A1, and B0, B1, B2 (112 to 116, respectively). In H.265, MV prediction can use predictors from the same reference picture that neighboring blocks use. Summary of the Invention [Means for solving the problem]

[0022] Aspects of the present disclosure provide a method and apparatus for video encoding / decoding. In some examples, a video decoding apparatus includes a processing circuit.

[0023] According to aspects of the disclosure, a method for video decoding in a decoder is provided. In the method, a processing circuit decodes prediction information for a current block in a current picture that is a part of a coded video sequence. The prediction information indicates an intra prediction direction for the current block, which is one of (i) a diagonal intra prediction direction or (ii) a neighboring intra prediction direction adjacent to the diagonal intra prediction direction. The processing circuit determines a usage of a position dependent prediction combination (PDPC) process according to the intra prediction direction of the current block. The same PDPC process is applied to both the diagonal intra prediction direction and the neighboring intra prediction direction. The processing circuit reconstructs the current block based on the usage of the PDPC process for the current block.

[0024] According to aspects of the present disclosure, the diagonal intra prediction direction is one of a bottom-left intra prediction direction and a top-right intra prediction direction. In an embodiment, if the diagonal intra prediction direction is a bottom-left intra prediction direction, the mode index of the neighboring intra prediction direction is lower than the mode index of the horizontal intra prediction direction. In an embodiment, if the diagonal intra prediction direction is a top-right intra prediction direction, the mode index of the neighboring intra prediction direction is higher than the mode index of the vertical intra prediction direction.

[0025] According to aspects of the present disclosure, if the intra prediction direction is a neighboring intra prediction direction, the processing circuit determines whether the intra prediction direction points to a fractional position. In response to determining that the intra prediction points to a fractional position, the processing circuit determines an early termination of the PDPC process.

[0026] According to aspects of the present disclosure, when a current sample in a current block is filtered by a PDPC process, the processing circuit determines whether the reference sample of the current sample is located within a preset range by row-wise or column-wise checking. In an embodiment, the column-wise checking depends on at least one of (i) the total number of available reference samples located to the left of the current block, (ii) the block height of the current block, and (iii) the horizontal coordinate value of the current sample. In an embodiment, the row-wise checking depends on at least one of (i) the total number of available reference samples located above the current block, (ii) the block width of the current block, and (iii) the vertical coordinate value of the current sample.

[0027] According to aspects of the present disclosure, the angle of the intra prediction direction is equal to or greater than a preset value. In an embodiment, if the intra prediction direction is closer to the vertical intra prediction direction than the horizontal intra prediction direction, the processing circuit performs the PDPC process on a first number of columns of samples in the current block, the first number being determined according to the preset value and a block size of the current block. In an embodiment, if the intra prediction direction is closer to the horizontal intra prediction direction than the vertical intra prediction direction, the processing circuit performs the PDPC process on a second number of rows of samples in the current block, the second number being determined according to the preset value and a block size of the current block.

[0028] 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 or a combination of the above methods for video decoding. [Brief description of the drawings]

[0029] Further features, nature and various advantages of the disclosed subject matter will become more apparent from the following detailed description and the accompanying drawings.

[0030] [Figure 1A] FIG. 2 is a schematic diagram of an example subset of intra-prediction modes.

[0031] [Figure 1B] FIG. 2 is an illustration of an exemplary intra-prediction direction.

[0032] [Figure 1C] FIG. 2 is a schematic diagram of a current block and its surrounding spatial merging candidates in one example.

[0033] [Diagram 2] FIG. 1 is a schematic diagram of a simplified block diagram of a communication system according to an embodiment.

[0034] [Diagram 3] FIG. 1 is a schematic diagram of a simplified block diagram of a communication system according to an embodiment.

[0035] [Figure 4] FIG. 2 is a schematic diagram of a simplified block diagram of a decoder according to an embodiment.

[0036] [Diagram 5] FIG. 2 is a schematic diagram of a simplified block diagram of an encoder according to an embodiment.

[0037] [Figure 6] 4 shows a block diagram of an encoder according to another embodiment;

[0038] [Figure 7] 4 shows a block diagram of a decoder according to another embodiment;

[0039] [Figure 8A] 1 shows an illustrative diagram of exemplary intra-prediction directions and corresponding intra-prediction modes in some examples (e.g., VVC).

[0040] [Figure 8B]1 shows a table of angular intra-prediction modes and their corresponding prediction angles in some examples (eg, VVC).

[0041] [Figure 9A] 13 illustrates an example weighting factor for a prediction sample at (0,0) in DC mode, according to an embodiment.

[0042] [Figure 9B] 13 illustrates an example weighting factor for a prediction sample at (1,0) in DC mode, according to an embodiment.

[0043] [Figure 10] 1 shows a flowchart outlining an exemplary process according to an embodiment of the present disclosure.

[0044] [Figure 11] 1 is a schematic diagram of a computer system according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] Video Encoders and Decoders

[0046] FIG. 2 illustrates a simplified block diagram of a communication system (200) according to an embodiment of the present disclosure. The communication system (200) includes a plurality of terminal devices that can communicate with each other, for example, via a network (250). For example, the communication system (200) includes a first pair of terminal devices (210) and (220) interconnected via the network (250). In the example of FIG. 2, the first pair of terminal devices (210) and (220) perform a unidirectional transmission of data. For example, the terminal device (210) may encode video data (e.g., a stream of video pictures captured by the terminal device (210)) for transmission to the other terminal device (220) via the network (250). The encoded video data can be transmitted in the form of one or more encoded video bitstreams. The terminal device (220) may receive encoded video data from the network (250), decode the encoded video data to recover a video picture, and display the video picture according to the recovered video data. One-way data transmission may be common in media service applications, etc.

[0047] In another example, the communication system (200) includes a second pair of terminal devices (230) and (240) performing bidirectional transmission of encoded video data, such as may occur during a video conference. For the bidirectional transmission of data, in one example, each of the terminal devices (230) and (240) may encode video data (e.g., a stream of video pictures captured by the terminal device) for transmission to the other of the terminal devices (230) and (240) over the network (250). Each of the terminal devices (230) and (240) may receive the encoded video data transmitted by the other of the terminal devices (230) and (240), decode the encoded video data to recover the video pictures, and display the video pictures on an accessible display device in accordance with the recovered video data.

[0048] In the example of FIG. 2, terminal devices (210), (220), (230), and (240) may be depicted as a server, a personal computer, and a smartphone, although the principles of the present disclosure may not be so limited. Embodiments of the present disclosure find application in laptop computers, tablet computers, media players, and / or dedicated video conferencing equipment. Network (250) represents any number of networks that convey encoded video data between terminal devices (210), (220), (230), and (240), including, for example, wired and / or wireless communication networks. Communication network (250) may exchange data in circuit-switched and / or packet-switched channels. Representative networks include telecommunications networks, local area networks, wide area networks, and / or the Internet. For purposes of the present discussion, the architecture and topology of network (250) may not be important to the operation of the present disclosure, unless otherwise described below.

[0049] 3 illustrates an arrangement of a video encoder and a video decoder in a streaming environment as an example of an application for the disclosed subject matter. The disclosed subject matter may be equally applicable to other video-enabled applications including, for example, video conferencing, digital TV, storage of compressed video on digital media including CDs, DVDs, memory sticks, etc.

[0050] The streaming system may include a video source (301), e.g., a digital camera, and may include a capture subsystem (313) that generates, e.g., a stream of uncompressed video pictures (302). In one example, the stream of video pictures (302) includes samples captured by a digital camera. The stream of video pictures (302), depicted as a thick line to emphasize its high data volume compared to the encoded video data (304) (or encoded video bitstream), may be processed by an electronic device (320) that includes a video encoder (303) coupled to the video source (301). The video encoder (303) may include hardware, software, or a combination thereof to enable or implement aspects of the disclosed subject matter, as described in more detail below. The encoded video data (304) (or encoded video bitstream (304)), depicted as a thin line to emphasize its lower data volume when compared to the stream of video pictures (302), can be stored in a streaming server (305) for future use. One or more streaming client subsystems, such as the client subsystems (306) and (308) of FIG. 3, can access the streaming server (305) to retrieve copies (307) and (309) of the encoded video data (304). The client subsystem (306) can include a video decoder (310), for example within the electronic device (330). The video decoder (310) decodes the incoming copy of the encoded video data (307) and generates an outgoing stream of video pictures (311) that can be rendered on a display (312) (e.g., a display screen) or other rendering device (not shown). In some streaming systems, the encoded video data (304), (307), and (309) (e.g., a video bitstream) may be encoded according to some video encoding / compression standard.Examples of these standards include ITU-T Recommendation H.265. In one example, the developing video coding standard is informally known as Versatile Video Coding (VVC). The disclosed subject matter may be used in the context of VVC.

[0051] It is noted that electronic devices (320) and (330) may include other components (not shown). For example, electronic device (320) may include a video decoder (not shown), and electronic device (330) may also include a video encoder (not shown).

[0052] 4 shows a block diagram of a video decoder (410) according to an embodiment of the present disclosure. The video decoder (410) can be included in an electronic device (430). The electronic device (430) can include a receiver (431) (e.g., a receiving circuit). The video decoder (410) can be used in place of the video decoder (310) in the example of FIG. 3.

[0053] The receiver (431) may receive one or more coded video sequences to be decoded by the video decoder (410); in the same or another embodiment, one coded video sequence at a time, with the decoding of each coded video sequence being independent of the other coded video sequences. The coded video sequences may be received from a channel (401), which may be a hardware / software link to a storage device that stores the encoded video data. The receiver (431) may receive the encoded video data together with other data, such as coded audio data and / or auxiliary data streams, which may be forwarded to respective usage entities (not shown). The receiver (431) may separate the coded video sequences from the other data. To combat network jitter, a buffer memory (415) may be coupled between the receiver (431) and the entropy decoder / parser (420) (hereinafter the "parser"). In some applications, the buffer memory (415) is part of the video decoder (410). In other applications, it may be external to the video decoder (410) (not shown). In still other applications, there may be a buffer memory (not shown) external to the video decoder (410), e.g., to combat network jitter, and yet another buffer memory (415) internal to the video decoder (410), e.g., to handle playback timing. If the receiver (431) is receiving data from a storage / forwarder of sufficient bandwidth and controllability, or from an isochronous network, the buffer memory (415) may not be required or may be small. For use in best-effort packet networks such as the Internet, the buffer memory (415) may be required and may be relatively large, advantageously of adaptive size, and may be implemented, at least in part, in an operating system or similar element (not shown) external to the video decoder (410).

[0054] The video decoder (410) may include a parser (420) for reconstructing symbols (421) from the coded video sequence. These categories of symbols include information used to manage the operation of the video decoder (410) and potentially information for controlling a rendering device such as a render device (412) (e.g., a display screen). The render device may be coupled to the electronic device (430) rather than being an integral part of the electronic device (430) as shown in FIG. 4. The control information for the rendering device(s) may be in the form of Supplementary Enhancement Information (SEI) messages or Video Usability Information (VUI) parameter set fragments (not shown). The parser (420) may parse / entropy decode the received coded video sequence. The coding of the coded video sequence may follow a video coding technique or standard and may follow various principles including variable length coding, Huffman coding, arithmetic coding with or without context sensitivity, etc. The parser (420) can extract from the coded video sequence a set of subgroup parameters for at least one of the subgroups of pixels in the video decoder based on at least one parameter corresponding to the group. The subgroups can include a Group of Pictures (GOP), a picture, a tile, a slice, a macroblock, a coding unit (CU), a block, a transform unit (TU), a prediction unit (PU), etc. The parser (420) can also extract information from the coded video sequence, such as transform coefficients, quantizer parameter values, motion vectors, etc.

[0055] The parser (420) performs an entropy decoding / parsing operation on the video sequence received from the buffer memory (415), thereby generating symbols (421).

[0056] The reconstruction of symbols (421) can involve several different units, depending on the type of coded video picture or its parts (e.g., inter and intra pictures, inter and intra blocks) and other factors. Which units are involved and how can be controlled by subgroup control information parsed by the parser (420) from the coded video sequence. The flow of such subgroup control information between the parser (420) and the following units is not depicted for clarity.

[0057] In addition to the functional blocks already mentioned, the video decoder (410) may be conceptually divided into several functional units, as described below. In a practical implementation working within commercial constraints, many of these units may interact closely with each other and may be at least partially integrated with each other. However, for purposes of describing the disclosed subject matter, the following conceptual subdivision into functional units is appropriate.

[0058] The first unit is a scaler / inverse transform unit (451). The scaler / inverse transform unit (451) receives quantized transform coefficients and control information as symbol(s) (421) from the parser (420). The control information includes which transform to use, block size, quantization factor, quantization scaling matrix, etc. The scaler / inverse transform unit (451) can output a block containing sample values ​​that can be input to an aggregator (455).

[0059] In some cases, the output samples of the scaler / inverse transform (451) may relate to intra-coded blocks, i.e. blocks that do not use prediction information from a previously reconstructed picture, but may use prediction information from a previously reconstructed part of the current picture. Such prediction information may be provided by an intra picture prediction unit (452). In some cases, the intra picture prediction unit (452) generates a block of the same size and shape as the block being reconstructed using surrounding already reconstructed information taken from a current picture buffer (458). The current picture buffer (458) may, for example, buffer a partially reconstructed current picture and / or a fully reconstructed current picture. The aggregator (455) may add, possibly on a sample-by-sample basis, the prediction information generated by the intra prediction unit (452) to the output sample information provided by the scaler / inverse transform unit (451).

[0060] In other cases, the output samples of the scaler / inverse transform unit (451) may relate to an inter-coded, potentially motion-compensated block. In such cases, the motion compensation prediction unit (453) may access a reference picture memory (457) to fetch samples used for prediction. After motion compensating the fetched samples according to the symbols (421) for the block, these samples may be added by an aggregator (455) to the output of the scaler / inverse transform unit (in this case referred to as residual samples or residual signals) to generate output sample information. The addresses in the reference picture memory (457) from which the motion compensation unit (453) fetches the prediction samples may be controlled by a motion vector available to the motion compensation unit (453) in the form of a symbol (421). The symbol may have, for example, X, Y, and reference picture components. Motion compensation may include interpolation of sample values ​​fetched from the reference picture memory (457) when subsample accurate motion vectors are used, motion vector prediction mechanisms, etc.

[0061] The output samples of the aggregator (455) can be subjected to various loop filtering techniques in a loop filter unit (456). Video compression techniques can include in-loop filter techniques that are controlled by parameters contained in the coded video sequence (also called coded video bitstream) and made available to the loop filter unit (456) as symbols (421) from the parser (420), but can also be responsive to meta-information obtained during decoding of a previous part (in decoding order) of the coded picture or coded video sequence, as well as to previously reconstructed loop filtered sample values.

[0062] The output of the loop filter unit (456) can be a sample stream, which can be output to a render device (412) or can be stored in a reference picture memory (457) for use in future inter-picture prediction.

[0063] Once an encoded picture is fully reconstructed, it can be used as a reference picture for future predictions. For example, once an encoded picture corresponding to a current picture is fully reconstructed and the encoded picture is identified (e.g., by the parser (420)) as a reference picture, the current picture buffer (458) can become part of the reference picture memory (457) and a fresh current picture buffer can be reallocated before starting the reconstruction of a subsequent encoded picture.

[0064] The video decoder (410) may perform decoding operations according to a given video compression technique in a standard, such as ITU-T Recommendation H.265. The coded video sequence may be compliant with the syntax prescribed by the video compression technique or standard being used, in the sense that the coded video sequence follows the syntax of the video compression technique or standard and the profile documented in the video compression technique or standard. Specifically, the profile may select certain tools from all tools available in the video compression technique or standard as the only tools available for use under that profile. Compliance may also require that the complexity of the coded video sequence be within a range defined by the level of the video compression technique or standard. In some cases, the level constrains the maximum picture size, maximum frame rate, maximum reconstruction sample rate (e.g., measured in units of megasamples per second), maximum reference picture size, etc. The limits set by the level may be further constrained through a Hypothetical Reference Decoder (HRD) specification and metadata for HRD buffer management, possibly signaled in the coded video sequence.

[0065] In some embodiments, the receiver (431) may receive additional (redundant) data along with the encoded video. The additional data may be included as part of the encoded video sequence(s). The additional data may be used by the video decoder (410) to properly decode the data and / or to more accurately reconstruct the original video data. The additional data may be in the form of, for example, temporal, spatial, or signal-to-noise ratio (SNR) improvement layers, redundant slices, redundant pictures, forward error correction codes, etc.

[0066] 5 shows a block diagram of a video encoder (503) according to one embodiment of the present disclosure. The video encoder (503) is included in an electronic device (520). The electronic device (520) includes a transmitter (540) (e.g., a transmission circuit). The video encoder (503) can be used in place of the video encoder (303) in the example of FIG. 3.

[0067] The video encoder (503) can receive video samples from a video source (501) (which is not part of the electronic device (520) in the example of FIG. 5) that can capture video images to be encoded by the video encoder (503). In another example, the video source (501) is part of the electronic device (520).

[0068] The video source (501) may provide a source video sequence to be encoded by the video encoder (503) in the form of a digital video sample stream that may be of any suitable bit depth (e.g., 8-bit, 10-bit, 12-bit, ...), any color space (e.g., BT.601 YCrCB, RGB, ...) and any suitable sampling structure (e.g., YCrCb 4:2:0, YCrCb 4:4:4). In a media service system, the video source (501) may be a storage device that stores pre-prepared video. In a video conferencing system, the video source (501) may be a camera that captures image information locally as a video sequence. The video data may be provided as a number of individual pictures that impart motion when viewed in sequence. The pictures themselves may be organized as a spatial array of pixels, each of which may contain one or more samples depending on the sampling structure, color space, etc. in use. Those skilled in the art can easily understand the relationship between pixels and samples. The following description focuses on samples.

[0069] According to an embodiment, the video encoder (503) can encode and compress pictures of a source video sequence into an encoded video sequence (543) in real-time or under any other time constraint required by an application. Enforcing an appropriate encoding rate is one function of the controller (550). In some embodiments, the controller (550) controls and is operatively coupled to other functional units, such as those described below. Such couplings are not depicted for clarity. Parameters set by the controller (550) can include parameters related to rate control (picture skip, quantizer, lambda value for rate-distortion optimization techniques, ...), picture size, group of pictures (GOP) layout, maximum motion vector allowable reference region, etc. The controller (550) can be configured with other suitable functions for the video encoder (503) optimized for a certain system design.

[0070] In some embodiments, the video encoder (503) is configured to operate in an encoding loop. As a simplistic description, in one example, the encoding loop can include a source encoder (530) (e.g., responsible for generating symbols, such as a symbol stream, based on an input picture to be encoded and a reference picture(s)) and a (local) decoder (533) embedded in the video encoder (503). The decoder (533) reconstructs the symbols to generate sample data in a similar manner that a (remote) decoder would also generate (in the video compression techniques considered in the disclosed subject matter, any compression between the symbols and the encoded video bitstream is lossless). The reconstructed sample stream (sample data) is input to a reference picture memory (534). Since the decoding of the symbol stream produces bit-accurate results regardless of the decoder location (local or remote), the contents of the reference picture memory (534) are also bit-accurate between the local and remote encoders. In other words, the prediction part of the encoder "sees" exactly the same sample values ​​as the reference picture samples that the decoder "sees" when using the prediction during decoding. This basic principle of reference picture synchrony (and the resulting drift when synchrony cannot be maintained, e.g., due to channel errors) is also used in several related technologies.

[0071] The operation of the "local" decoder (533) may be the same as the operation of a "remote" decoder, e.g., the video decoder (410), already described in detail above in connection with Figure 4. However, referring also briefly to Figure 4, since symbols are available and the encoding / decoding of symbols into a coded video sequence by the entropy coder (545) and parser (420) may be lossless, the entropy decoding portion of the video decoder (410), including the buffer memory (415) and the parser (420), may not be fully implemented in the local decoder (533).

[0072] An observation that can be made at this point is that any decoder technique, except for parsing / entropy decoding, that exists in the decoder must exist in substantially the same functional form in the corresponding encoder. For this reason, the disclosed subject matter focuses on the decoder operation. The description of the encoder techniques can be abbreviated since they are the inverse of the decoder techniques, which are described generically. Only in certain areas is more detailed explanation necessary, and is provided below.

[0073] During operation, in some examples, the source encoder (530) may perform motion-compensated predictive encoding, which predictively encodes an input picture with reference to one or more previously encoded pictures from a video sequence, designated as “reference pictures.” In this manner, the encoding engine (532) encodes differences between pixel blocks of the input picture and pixel blocks of the reference picture(s) that may be selected as predictive references for the input picture.

[0074] The local video decoder (533) can decode the coded video data of pictures that may be designated as reference pictures based on the symbols generated by the source encoder (530). The operation of the coding engine (532) can advantageously be a lossy process. When the coded video data can be decoded by a video decoder (not shown in FIG. 5), the reconstructed video sequence can be a copy of the source video sequence, typically with some errors. The local video decoder (533) can replicate the decoding process that may be performed on the reference pictures by the video decoder and store the reconstructed reference pictures in a reference picture cache (534). In this way, the video encoder (503) can locally store copies of reconstructed reference pictures that have common content (in the absence of transmission errors) as the reconstructed reference pictures that would be obtained by the far-end video decoder.

[0075] The predictor (535) may perform a prediction search for the coding engine (532). That is, for a new picture to be coded, the predictor (535) may search the reference picture memory (534) for sample data (as candidate reference pixel blocks) or certain metadata, such as reference picture motion vectors, block shapes, etc., that may serve as suitable prediction references for the new picture. The predictor (535) may operate on a sample block-by-pixel block basis to find suitable prediction references. In some cases, as determined by the search results obtained by the predictor (535), the input picture may have prediction references derived from multiple reference pictures stored in the reference picture memory (534).

[0076] The controller (550) may manage the encoding operations of the source encoder (530), including, for example, setting the parameters and subgroup parameters used to encode the video data.

[0077] The output of all the above functional units can be subjected to entropy coding in an entropy coder (545), which converts the symbols produced by the various functional units into a coded video sequence by losslessly compressing the symbols according to techniques such as Huffman coding, variable length coding, arithmetic coding, etc.

[0078] The transmitter (540) can buffer the coded video sequence produced by the entropy coder (545) and prepare it for transmission over a communication channel (560), which may be a hardware / software link to a storage device that stores the encoded video data. The transmitter (540) can merge the coded video data from the video coder (530) with other data to be transmitted, such as coded audio data and / or auxiliary data streams (sources not shown).

[0079] A controller (550) may manage the operation of the video encoder (503). During encoding, the controller (550) may assign a coding picture type to each coded picture. The coding picture type may affect the coding technique that may be applied to each picture. For example, pictures may often be assigned as one of the following picture types:

[0080] An intra picture (I picture) may be one that can be coded and decoded without using other pictures in a sequence as a source of prediction. Some video codecs allow different types of intra pictures, including, for example, Independent Decoder Refresh ("IDR") pictures. Those skilled in the art will recognize these variations of I pictures, as well as their respective uses and characteristics.

[0081] A predictive picture (P picture) may be one that can be encoded and decoded using intra- or inter-prediction, which uses at most one motion vector and reference index to predict the sample values ​​of each block.

[0082] A bidirectionally predictive picture (B picture) may be one that can be encoded and decoded using intra- or inter-prediction that uses up to two motion vectors and reference indices to predict the sample values ​​of each block. Similarly, a multi-predictive picture may use more than two reference pictures and associated metadata for the reconstruction of a single block.

[0083] A source picture is usually spatially divided into multiple sample blocks (e.g., blocks of 4x4, 8x8, 4x8, or 16x16 samples each) and may be coded block by block. Blocks may be predictively coded with reference to other (already coded) blocks, as determined by the coding assignment applied to the respective picture of the block. For example, blocks of an I picture may be non-predictively coded or predictively coded with reference to already coded blocks of the same picture (spatial or intra prediction). Pixel blocks of a P picture may be predictively coded via spatial prediction or via temporal prediction with reference to one previously coded reference picture. Blocks of a B picture may be predictively coded via spatial prediction or via temporal prediction with reference to one or two previously coded reference pictures.

[0084] The video encoder (503) may perform encoding operations according to a given video encoding technique or standard, such as ITU-T Recommendation H.265. In its operations, the video encoder (503) may perform various compression operations, including predictive encoding operations that exploit temporal and spatial redundancy in the input video sequence. Thus, the encoded video data may conform to a syntax specified by the video encoding technique or standard used.

[0085] In some embodiments, the sender (540) may transmit additional data along with the encoded video. The source encoder (530) may include such data as part of the encoded video sequence. The additional data may include temporal / spatial / SNR enhancement layers, other forms of redundant data such as redundant pictures and slices, SEI messages, VUI parameter set fragments, etc.

[0086] Video may be captured as multiple source pictures (video pictures) in a temporal sequence. Intra-picture prediction (often abbreviated as intra-prediction) exploits spatial correlations in a given picture, while inter-picture prediction exploits correlations (temporal or otherwise) between pictures. In one example, a particular picture to be encoded / decoded, called the current picture, is divided into blocks. If a block in the current picture is similar to a reference block in a previously coded and still buffered reference picture in the video, that block in the current picture can be coded by a vector called a motion vector. The motion vector points to a reference block in the reference picture, and may have a third dimension that identifies the reference picture if multiple reference pictures are used.

[0087] In some embodiments, bi-prediction techniques can be used in inter-picture prediction. According to bi-prediction techniques, two reference pictures are used, such as a first reference picture and a second reference picture, both of which precede the current picture in decoding order (but may be past and future, respectively, in display order) in the video. A block in the current picture can be coded by a first motion vector that points to a first reference block in the first reference picture and a second motion vector that points to a second reference block in the second reference picture. A block can be predicted by a combination of the first reference block and the second reference block.

[0088] Furthermore, to improve coding efficiency, merge mode techniques can be used in inter-picture prediction.

[0089] According to some embodiments of the present disclosure, predictions such as inter-picture prediction and intra-picture prediction are performed on a block-by-block basis. For example, according to the HEVC standard, pictures in a sequence of video pictures are divided into coding tree units (CTUs) for compression, and the CTUs in a picture have the same size, such as 64×64 pixels, 32×32 pixels, or 16×16 pixels. In general, a CTU includes three coding tree blocks (CTBs), one luma CTB and two chroma CTBs. Each CTU can be recursively quadtree partitioned into one or more coding units (CUs). For example, a CTU of 64×64 pixels can be partitioned into one CU of 64×64 pixels, or four CUs of 32×32 pixels, or 16 CUs of 16×16 pixels. In one example, each CU is analyzed to determine a prediction type for that CU, such as an inter prediction type or an intra prediction type. A CU is divided into one or more prediction units (PUs) depending on temporal and / or spatial predictability. Generally, each PU includes a luma prediction block (PB) and two chroma PBs. In an embodiment, the prediction operation in encoding / decoding is performed in units of a prediction block. Taking a luma prediction block as an example of a prediction block, the prediction block includes a matrix of values ​​(e.g., luma values) for pixels, such as 8×8 pixels, 16×16 pixels, 8×16 pixels, 16×8 pixels, etc.

[0090] 6 shows a diagram of a video encoder (603) according to another embodiment of the present disclosure. The video encoder (603) is configured to receive a processed block of sample values ​​(e.g., a predictive block) in a current video picture in a sequence of video pictures and to encode the processed block into a coded picture that is part of a coded video sequence. In one example, the video encoder (603) is used in place of the video encoder (303) in the example of FIG. 3.

[0091] In an HEVC example, the video encoder (603) receives a matrix of sample values ​​for a processing block, such as a predictive block, such as 8×8 samples. The video encoder (603) determines whether the processing block is best coded using intra mode, inter mode, or bi-predictive mode, e.g., using rate-distortion optimization. If the processing block is coded in intra mode, the video encoder (603) may use intra prediction techniques to encode the processing block into a coded picture; if the processing block is coded in inter mode or bi-predictive mode, the video encoder (603) may use inter prediction techniques or bi-predictive techniques, respectively, to encode the processing block into a coded picture. In certain video coding techniques, a merge mode may be an inter-picture prediction submode in which motion vectors are derived from one or more motion vector predictors, but without the benefit of coded motion vector components outside the predictors. In certain other video coding techniques, there may be motion vector components applicable to the current block. In one example, the video encoder (603) includes other components, such as a mode decision module (not shown) for determining a mode of a processing block.

[0092] In the example of FIG. 6, the video encoder (603) includes an inter-encoder (630), an intra-encoder (622), a residual calculator (623), a switch (626), a residual encoder (624), a general controller (621), and an entropy coder (625), coupled together as shown in FIG. 6.

[0093] The inter encoder (630) is configured to receive samples of a current block (e.g., a processing block), compare the block with one or more reference blocks in a reference picture (e.g., blocks in previous and subsequent pictures), generate inter prediction information (e.g., a description of redundant information due to inter encoding techniques, motion vectors, merge mode information), and calculate an inter prediction result (e.g., a predicted block) based on the inter prediction information using any suitable technique. In some examples, the reference picture is a decoded reference picture that has been decoded based on the encoded video information.

[0094] The intra encoder (622) is configured to receive samples of a current block (e.g., a processing block), optionally compare the block with blocks already encoded in the same picture, generate transformed and quantized coefficients, and optionally generate intra prediction information (e.g., intra prediction direction information according to one or more intra encoding techniques). In one example, 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.

[0095] The general controller (621) is configured to determine general control data and control other components of the video encoder (603) based on the general control data. In one example, the general controller (621) determines a mode of the block and provides a control signal to the switch (626) based on the mode. For example, if 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 include the intra prediction information in the bitstream; if 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 include the inter prediction information in the bitstream.

[0096] 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). The residual encoder (624) is configured to encode the residual data to generate transform coefficients based on the residual data. In one example, the residual encoder (624) is configured to transform the residual data from a spatial domain to a frequency domain to generate transform coefficients. The transform coefficients are then subjected to a quantization process to obtain quantized transform coefficients. In various embodiments, the video encoder (603) also includes a residual decoder (628). The residual decoder (628) is configured to perform an inverse transform to generate decoded residual data. The decoded residual data can be suitably used by the intra-encoder (622) and the inter-encoder (630). For example, the inter-encoder (630) can generate decoded blocks based on the decoded residual data and the inter-prediction information, and the intra-encoder (622) can generate decoded blocks based on the decoded residual data and the intra-prediction information. The decoded blocks are suitably processed to generate decoded pictures, which can be buffered in a memory circuit (not shown) and, in some examples, used as reference pictures.

[0097] The entropy encoder (625) is configured to format a bitstream to include the encoded block. The entropy encoder (625) is configured to include various information according to a suitable standard, such as the HEVC standard. In one example, 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 is noted that, in accordance with the disclosed subject matter, when encoding a block in a merged sub-mode of either the inter mode or the bi-prediction mode, the residual information is not present.

[0098] 7 shows a diagram of a video decoder (710) according to another embodiment of the present disclosure. The video decoder (710) is configured to receive coded pictures that are part of a coded video sequence and decode the coded pictures to generate reconstructed pictures. In one example, the video decoder (710) is used in place of the video decoder (310) in the example of FIG. 3.

[0099] In the example of FIG. 7, the 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.

[0100] The entropy decoder (771) may be configured to reconstruct from the coded picture certain symbols that represent the syntax elements of which the coded picture is composed. Such symbols may include, for example, prediction information (e.g., intra- or inter-prediction information, etc.) that may identify the mode in which the block is coded (e.g., intra- or inter-prediction mode, merged submode or the latter two in another submode), certain samples or metadata used for prediction by the intra-decoder (772) or the inter-decoder (780), respectively, residual information, e.g., in the form of quantized transform coefficients, etc. In one example, if the prediction mode is an inter- or bi-prediction mode, the inter-prediction information is provided to the inter-decoder (780); if the prediction type is an intra-prediction type, the intra-prediction information is provided to the intra-decoder (772). The residual information may undergo inverse quantization and is provided to the residual decoder (773).

[0101] The inter decoder (780) is configured to receive inter prediction information and generate inter prediction results based on the inter prediction information.

[0102] The intra decoder (772) is configured to receive intra prediction information and generate a prediction result based on the intra prediction information.

[0103] The residual decoder (773) is configured to perform inverse quantization to extract dequantized transform coefficients, and to process the dequantized transform coefficients to transform the residual from the frequency domain to the spatial domain. The residual decoder (773) may also require certain control information (including quantizer parameters (QP)), which may be provided by the entropy decoder (771) (data path not depicted since this is only low-volume control information).

[0104] The reconstruction module (774) is configured to combine, in the spatial domain, the residual output by the residual decoder (773) and the prediction result (output by the intra- or inter-prediction module, as the case may be) to form a reconstructed block, which may be part of a reconstructed picture, which may be part of a reconstructed video. It is noted that other suitable operations, such as deblocking operations, may be performed to improve visual quality.

[0105] It should be noted that the video encoders (303), (503), (603) and the video decoders (310), (410), (710) may be implemented using any suitable techniques. In one embodiment, the video encoders (303), (503), (603) and the video decoders (310), (410), (710) may be implemented using one or more integrated circuits. In another embodiment, the video encoders (303), (503), (603) and the video decoders (310), (410), (710) may be implemented using one or more processors executing software instructions.

[0106] Intra Prediction in VVC

[0107] 8A shows an explanatory diagram of exemplary intra-prediction directions and corresponding intra-prediction modes in some examples (e.g., VVC). In FIG. 8A, there are a total of 95 intra-prediction modes (modes -14 to 80), of which mode 0 is a planar mode (referred to as INTRA_PLANAR), mode 1 is a DC mode (referred to as INTRA_DC), and the other modes (modes -14 to -1 and modes 2 to 80) are angular (or directional) modes (also referred to as INTRA_ANGULAR). Among the angular (or directional) modes, mode 18 (referred to as INTRA_ANGULAR18) is a horizontal mode, mode 50 (referred to as INTRA_ANGULAR50) is a vertical mode, mode 2 (referred to as INTRA_ANGULAR2) is a diagonal mode pointing in the lower left direction, mode 34 (referred to as INTRA_ANGULAR34) is a diagonal mode pointing in the upper left direction, and mode 66 (referred to as INTRA_ANGULAR66) is a diagonal mode pointing in the upper right direction. Modes -14 to -1 and modes 67 to 80 are referred to as wide-angle intra prediction (WAIP) modes. Exemplary angular intra prediction modes and their corresponding intra prediction angles are tabulated in FIG. 8B.

[0108] Position-dependent predictive combination (PDPC) filtering process

[0109] According to aspects of the present disclosure, position dependent prediction combination (PDPC) may be applied to the following intra modes without signaling: planar, DC, WAIP mode, horizontal, vertical, bottom left angular mode (mode 2) and its eight adjacent angular modes (modes 3-10), and top right angular mode (mode 66) and its eight adjacent angular modes (modes 58-65).

[0110] In one embodiment, the prediction sample pred'[x][y] located at position (x, y) in the current block is predicted using an intra prediction mode (e.g., DC, planar, or angular mode) and a linear combination of reference samples according to equation (1).

number

[0111] In an embodiment, when the intra prediction mode is a DC mode, the weighting factor may be calculated according to equations (2) to (5).

number

[0112] In one embodiment, if the intra prediction mode is a planar mode, wTL is set to 0, if the intra prediction mode is a horizontal mode, wTL is set equal to wT, and if the intra prediction mode is a vertical mode, wTL is set equal to wL. The PDPC weighting factor can be calculated with addition and shift operations. The value of pred'[x][y] can be calculated in a single step using equation (1).

[0113] 9A shows an example weighting factor for a prediction sample at (0,0) in DC mode. In the example of FIG. 9A, the current block is a 4×4 block (width=height=4), so nScale is 0. Then wT is 32, wL is 32, and wTL is 4.

[0114] 9B shows an example weighting factor for a prediction sample at (1,0) in DC mode. In the example of FIG. 9B, the current block is a 4×4 block (width=height=4), so nScale is 0. Then wT is 32, wL is 8, and wTL is 2.

[0115] In some embodiments, when the PDPC filtering process is applied to DC, planar, horizontal, and vertical intra modes, no additional boundary filters, such as the HEVC DC mode boundary filter or the horizontal / vertical mode edge filters, are required.

[0116] An exemplary PDPC filtering process

[0117] In some examples, inputs to the PDPC filtering process include: · Intra prediction mode represented by preModeIntra; The width of the current block, expressed as nTbW; · the height of the current block, represented by nTbH; The width of the reference sample represented by refW; · the height of the reference sample represented by refH; · predicted samples represented by predSamples[x][y], where x = 0...nTbW-1, y = 0...nTbH-1; · Unfiltered reference (also called neighborhood) samples, denoted by p[x][y], where x=-1, y=-1…refH-1 and x=0…refW-1, y=-1; The color component of the current block represented by cIdx.

[0118] Depending on the value of cIdx, the function clip1Cmp is set as follows: If cIdx is equal to 0, clip1Cmp is Clip1 Y is set equal to; Otherwise, clip1Cmp is Clip1 C is set equal to

[0119] Furthermore, the output of the PDPC filtering process is the modified predicted samples predSamples'[x][y], x = 0...nTbW-1, y = 0...nTbH-1.

[0120] The scaling factor nScale may then be calculated according to equation (6).

number

[0121] Furthermore, a reference sample array mainRef[x], x = 0...refW may be defined as an array of unfiltered reference samples above the current block, and another reference sample array sideRef[y], y = 0...refH may be defined as an array of unfiltered reference samples to the left of the current block. The reference sample arrays mainRef[x] and sideRef[y] may be derived from the unfiltered reference samples according to equations (7)-(8), respectively.

number

[0122] For each position (x,y) in the current block, the PDPC calculation may use the reference sample at the top, denoted as refT[x][y], the reference sample at the left, denoted as refL[x][y], and the reference sample at the corner, p[-1,-1]. The modified predicted sample may be calculated according to equation (9), and the result is suitably clipped according to the variable cIdx indicating the color component.

number

[0123] The reference samples refT[x][y], refL[x][y] and the weighting factors wL, wT and wTL may be determined based on the intra prediction mode preModeIntra.

[0124] When the intra prediction mode preModeIntra is equal to INTRA_PLANAR (e.g., 0, planar mode, or mode 0) or INTRA_DC (e.g., 1, DC mode, or mode 1), the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT and wTL may be determined according to equations (10) to (14).

number

[0125] Otherwise, if the intra prediction mode preModeIntra is equal to INTRA_ANGULAR18 (e.g., 18, horizontal mode, or mode 18) or INTRA_ANGULAR50 (e.g., 50, vertical mode, or mode 50), the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT and wTL may be determined according to equations (15) to (19).

number

[0126] Otherwise, if the intra prediction mode preModeIntra is equal to INTRA_ANGULAR2 (e.g., 2, or mode 2) or INTRA_ANGULAR66 (e.g., 66, or mode 66), the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT and wTL may be determined according to equations (20) to (24).

number

[0127] Otherwise, if the intra-prediction mode preModeIntra is less than or equal to INTRA_ANGULAR10 (e.g., 10 or mode 10), then for each position (x, y), the variables dXPos[y], dXFrac[y], dXInt[y], and dX[x][y] may be derived based on a variable invAngle, which is a function of the intra-prediction mode preModeIntra. invAngle may be determined based on a lookup table that stores corresponding invAngle values ​​for each intra-prediction mode, and then the reference samples refT[x][y], refL[x][y], and weighting factors wL, wT, and wTL may be determined based on the variables dXPos[y], dXFrac[y], dXInt[y], and dX[x][y].

[0128] The variables dXPos[y], dXFrac[y], dXInt[y], and dX[x][y] may be determined according to equations (25)-(28).

number

[0129] Then, the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL may be determined according to equations (29)-(33).

number

[0130] Otherwise, if the intra-prediction mode preModeIntra is greater than or equal to INTRA_ANGULAR58 (e.g., 58, or mode 58), the variables dYPos[x], dYFrac[x], dYInt[x], and dY[x][y] may be derived based on a variable invAngle, which is a function of the intra-prediction mode preModeIntra. invAngle may be determined based on a lookup table that stores corresponding invAngle values ​​for each intra-prediction mode, and then the reference samples refT[x][y], refL[x][y], and weighting factors wL, wT, and wTL may be determined based on the variables dYPos[x], dYFrac[x], dYInt[x], and dY[x][y].

[0131] The variables dYPos[x], dYFrac[x], dYInt[x], and dY[x][y] may be determined according to equations (34)-(37).

number

[0132] Then, the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL may be determined according to equations (38)-(42).

number

[0133] Otherwise, if the variable preModeIntra is between modes 11 and 57, and is neither mode 18 nor mode 50, then the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL are all set equal to 0.

[0134] Finally, the filtered sample values ​​filtSamples[x][y], x = 0...nTbW-1, y = 0...nTbH-1 may be derived according to equation (43).

number

[0135] In some examples (e.g., in VVC), when performing intra prediction using PDPC for a nTbW×nTbH transform block in a nCbW×nCbH current block, if the current block is not coded in intra sub-partition (ISP) mode (i.e., IntraSubPartitionsSplitType is equal to ISP_NO_SPLIT as shown in VVC draft v5), the range of available reference samples above (refW) is set as 2×nTbW, and the range of available reference samples to the left (refH) is set as 2×nTbH. Otherwise, if ISP is applied to the current block (i.e., IntraSubPartitionsSplitType is not equal to ISP_NO_SPLIT as shown in VVC draft v5), the range of available reference samples above (refW) is set as 2×nCbW, and the range of available reference samples to the left (refH) is set as 2×nCbH.

[0136] Improvement techniques for PDPC

[0137] In the above section "Exemplary PDPC Filtering Process" or some related examples (e.g., in VTM5.0), a different PDPC process may be applied to intra-coded blocks having a diagonal intra-prediction mode and modes adjacent to the diagonal intra-prediction mode. For example, a different PDPC process may be applied to mode 2 and its adjacent modes (e.g., mode index 10 or less). In another example, a different PDPC process is applied to mode 66 and its adjacent modes (e.g., mode index 58 or greater). However, the prediction processes of the diagonal prediction modes and their adjacent modes are similar, and there is no clear advantage to maintaining different PDPC processes for these modes. Thus, aspects of the present disclosure provide an improvement technique for the PDPC process.

[0138] The techniques or methods of the present application may be used separately or in combination in any order. Note that in the following sections, PDPC may be used as a general term for a position-dependent boundary filtering process for a predicted sample that applies a linear combination of the predicted sample and nearby reconstructed samples with position-dependent weighting, the result of which may be used to replace the original predicted sample. Thus, the PDPC process is not limited to the process described in the section "Exemplary PDPC Filtering Process" above.

[0139] Further, in the following description, the diagonal intra prediction modes may be mode 2 and mode 66 in FIG. 8A, and the modes adjacent to mode 2 may have mode indices smaller than the horizontal modes (e.g., intra mode indexes smaller than 18), and the modes adjacent to mode 66 may have mode indices larger than the vertical modes (e.g., intra mode indexes greater than 50).

[0140] According to aspects of this disclosure, the same PDPC process (e.g., same range of available reference samples, same weighting factor applied for each position) is applied to the diagonal intra prediction mode and modes adjacent to the diagonal intra prediction mode.

[0141] In one embodiment, the diagonal intra prediction modes may be mode 2 and mode 66 in FIG. 8A, and the modes adjacent to the diagonal intra prediction modes may be modes -1 to -14, modes 3 to 10, modes 58 to 65, and modes 67 to 80 in FIG. 8A.

[0142] In an embodiment, for a block using a diagonal prediction mode, only a subset of available neighboring reference samples may be used by the PDPC process, while for a block using modes adjacent to the diagonal prediction mode, all available neighboring reference samples may be used by the PDPC process. For example, in the PDPC process for a block predicted using a diagonal intra prediction mode (e.g., mode 2 and mode 66 in VVC draft v5), only refW-K upper neighboring reference samples and refH-K left neighboring reference samples are used, where refW and refH respectively indicate the total number of available upper and left reference samples (specified in the "General Intra Sample Prediction" section of VVC draft v5 and also described in the section "Exemplary PDPC Filtering Process" above), and K is a positive integer (e.g., 1, 2, 3, or 4).

[0143] In an embodiment, for diagonal modes (eg, mode 2 and mode 66 in VVC draft v5), all available top and left reference samples can be used for PDPC, except for the right-most and bottom-most samples.

[0144] Exemplary modifications to the PDPC process

[0145] In some embodiments (eg, embodiments A through E below), the PDPC process can be modified as follows. EXAMPLES

[0146] Embodiment A

[0147] Exemplary inputs to the PDPC filtering process include: · Intra prediction mode represented by preModeIntra; The width of the current block, expressed as nTbW; · the height of the current block, represented by nTbH; The width of the reference sample represented by refW; · the height of the reference sample represented by refH; · predicted samples represented by predSamples[x][y], where x = 0...nTbW-1, y = 0...nTbH-1; · Unfiltered reference (also called neighborhood) samples, denoted by p[x][y], where x=-1, y=-1…refH-1 and x=0…refW-1, y=-1; The color component of the current block represented by cIdx.

[0148] Depending on the value of cIdx, the function clip1Cmp is set as follows: If cIdx is equal to 0, clip1Cmp is Clip1 Y is set equal to; Otherwise, clip1Cmp is Clip1 C is set equal to

[0149] Furthermore, the output of the PDPC filtering process is the modified predicted samples predSamples'[x][y], x = 0...nTbW-1, y = 0...nTbH-1.

[0150] The scaling factor nScale can then be calculated according to equation (44).

number

[0151] Furthermore, a reference sample array mainRef[x], x = 0...refW may be defined as an array of unfiltered reference samples above the current block, and another reference sample array sideRef[y], y = 0...refH may be defined as an array of unfiltered reference samples to the left of the current block. The reference sample arrays mainRef[x] and sideRef[y] may be derived from the unfiltered reference samples according to Equations (45)-(46), respectively.

number

[0152] For each position (x,y) in the current block, the PDPC calculation may use a reference sample at the top denoted as refT[x][y], a reference sample at the left denoted as refL[x][y], and a reference sample at the corner p[-1,-1]. In some examples, the modified predicted sample may be calculated according to equation (47), with the result suitably clipped according to a variable cIdx indicating the color component.

number

[0153] The reference samples refT[x][y], refL[x][y] and the weighting factors wL, wT and wTL may be determined based on the intra prediction mode preModeIntra.

[0154] When the intra prediction mode preModeIntra is equal to INTRA_PLANAR (e.g., 0, planar mode, or mode 0) or INTRA_DC (e.g., 1, DC mode, or mode 1), the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT and wTL may be determined according to equations (48) to (52).

number

[0155] Otherwise, if the intra prediction mode preModeIntra is equal to INTRA_ANGULAR18 (e.g., 18, horizontal mode, or mode 18) or INTRA_ANGULAR50 (e.g., 50, vertical mode, or mode 50), the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT and wTL may be determined according to equations (53) to (57).

number

[0156] Otherwise, if the intra-prediction mode preModeIntra is less than or equal to INTRA_ANGULAR10 (e.g., 10 or mode 10), then for each position (x, y), the variables dXPos[y], dXFrac[y], dXInt[y], and dX[x][y] may be derived based on a variable invAngle, which is a function of the intra-prediction mode preModeIntra. invAngle may be determined based on a lookup table that stores corresponding invAngle values ​​for each intra-prediction mode, and then the reference samples refT[x][y], refL[x][y], and weighting factors wL, wT, and wTL may be determined based on the variables dXPos[y], dXFrac[y], dXInt[y], and dX[x][y].

[0157] For example, the variables dXPos[y], dXFrac[y], dXInt[y], and dX[x][y] may be determined according to equations (58)-(61).

number

[0158] The reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL may then be determined according to equations (62)-(66).

number

[0159] Otherwise, if the intra-prediction mode preModeIntra is greater than or equal to INTRA_ANGULAR58 (e.g., 58, or mode 58), the variables dYPos[x], dYFrac[x], dYInt[x], and dY[x][y] may be derived based on a variable invAngle, which is a function of the intra-prediction mode preModeIntra. invAngle may be determined based on a lookup table that stores corresponding invAngle values ​​for each intra-prediction mode, and then the reference samples refT[x][y], refL[x][y], and weighting factors wL, wT, and wTL may be determined based on the variables dYPos[x], dYFrac[x], dYInt[x], and dY[x][y].

[0160] For example, the variables dYPos[x], dYFrac[x], dYInt[x], and dY[x][y] may be determined according to equations (67)-(70).

number

[0161] The reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL may then be determined according to equations (71)-(75).

number

[0162] Otherwise, if the variable preModeIntra is between modes 11 and 57, and is neither mode 18 nor mode 50, then the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL are all set equal to 0.

[0163] Finally, the filtered sample values ​​filtSamples[x][y], x = 0...nTbW-1, y = 0...nTbH-1 may be derived according to equation (76).

number

[0164] The difference between embodiment A and the above section "Exemplary PDPC Filtering Process" is that in embodiment A, the same PDPC process is applied to the diagonal intra-prediction mode and modes adjacent to the diagonal intra-prediction mode. In one example, the same PDPC process is applied to mode 2 and modes adjacent to mode 2 (e.g., mode index 10 or less). In another example, the same PDPC process is applied to mode 66 and modes adjacent to mode 66 (e.g., mode index 58 or greater). EXAMPLES

[0165] Embodiment B

[0166] Exemplary inputs to the PDPC filtering process include the following: · Intra prediction mode represented by preModeIntra; The width of the current block, expressed as nTbW; · the height of the current block, represented by nTbH; The width of the reference sample represented by refW; · the height of the reference sample represented by refH; · predicted samples represented by predSamples[x][y], where x = 0...nTbW-1, y = 0...nTbH-1; · Unfiltered reference (also called neighborhood) samples, denoted by p[x][y], where x=-1, y=-1…refH-1 and x=0…refW-1, y=-1; The color component of the current block represented by cIdx.

[0167] Depending on the value of cIdx, the function clip1Cmp is set as follows: If cIdx is equal to 0, clip1Cmp is Clip1 Y is set equal to; Otherwise, clip1Cmp is Clip1 C is set equal to

[0168] Furthermore, the output of the PDPC filtering process is the modified predicted samples predSamples'[x][y], x = 0...nTbW-1, y = 0...nTbH-1.

[0169] The scaling factor nScale can then be calculated according to equation (77).

number

[0170] Furthermore, a reference sample array mainRef[x], x = 0...refW may be defined as an array of unfiltered reference samples above the current block, and another reference sample array sideRef[y], y = 0...refH may be defined as an array of unfiltered reference samples to the left of the current block. The reference sample arrays mainRef[x] and sideRef[y] may be derived from the unfiltered reference samples according to equations (78)-(79), respectively.

number

[0171] For each position (x,y) in the current block, the PDPC calculation may use a reference sample at the top denoted as refT[x][y], a reference sample at the left denoted as refL[x][y], and a reference sample at the corner p[-1,-1]. In some examples, the modified predicted sample may be calculated according to equation (80), with the result suitably clipped according to a variable cIdx indicating the color component.

number

[0172] The reference samples refT[x][y], refL[x][y] and the weighting factors wL, wT and wTL may be determined based on the intra prediction mode preModeIntra.

[0173] When the intra prediction mode preModeIntra is equal to INTRA_PLANAR (e.g., 0, planar mode, or mode 0) or INTRA_DC (e.g., 1, DC mode, or mode 1), the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT and wTL may be determined according to equations (81) to (85).

number

[0174] Otherwise, if the intra prediction mode preModeIntra is equal to INTRA_ANGULAR18 (e.g., 18, horizontal mode, or mode 18) or INTRA_ANGULAR50 (e.g., 50, vertical mode, or mode 50), the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT and wTL may be determined according to equations (86) to (90).

number

[0175] Otherwise, if the intra-prediction mode preModeIntra is less than or equal to INTRA_ANGULAR10 (e.g., 10 or mode 10), then for each position (x, y), the variables dXPos[y], dXInt[y], and dX[x][y] may be derived based on a variable invAngle, which is a function of the intra-prediction mode preModeIntra. invAngle may be determined based on a lookup table that stores a corresponding invAngle value for each intra-prediction mode, and then the reference samples refT[x][y], refL[x][y], and weighting factors wL, wT, and wTL may be determined based on the variables dXPos[y], dXInt[y], and dX[x][y].

[0176] The variables dXPos[y], dXInt[y], and dX[x][y] may be determined according to equations (91)-(93).

number

[0177] The reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL may then be determined according to equations (94)-(98).

number

[0178] Otherwise, if the intra-prediction mode preModeIntra is greater than or equal to INTRA_ANGULAR58 (e.g., 58, or mode 58), the variables dYPos[x], dYInt[x], and dY[x][y] may be derived based on a variable invAngle, which is a function of the intra-prediction mode preModeIntra. invAngle may be determined based on a lookup table that stores corresponding invAngle values ​​for each intra-prediction mode, and then the reference samples refT[x][y], refL[x][y], and weighting factors wL, wT, and wTL may be determined based on the variables dYPos[x], dYInt[x], and dY[x][y].

[0179] For example, the variables dYPos[x], dYInt[x], and dY[x][y] may be determined according to equations (99)-(101).

number

[0180] The reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL may then be determined according to equations (102)-(106).

number

[0181] Otherwise, if the variable preModeIntra is between modes 11 and 57, and is neither mode 18 nor mode 50, then the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL are all set equal to 0.

[0182] Finally, the values ​​of the filtered samples filtSamples[x][y], x = 0...nTbW-1, y = 0...nTbH-1 may be derived according to equation (107).

number

[0183] The difference between embodiment A and embodiment B is that in embodiment B, when the intra prediction mode preModeIntra is less than or equal to INTRA_ANGULAR10, dXFrac[y] (equation (59)) is not calculated, dXInt[y] may be calculated differently (i.e., equation (60) versus equation (92)), and therefore refT[x][y] and wT[y] are calculated differently than in embodiment A (i.e., equation (63) versus equation (95), equation (64) versus equation (96)). Similarly, when the intra prediction mode preModeIntra is INTRA_ANGULAR58 or higher, in embodiment B, dYFrac[x] (equation (68)) is not calculated and dYInt[x] may be calculated differently (i.e., equation (69) versus equation (100)), and thus refL[x][y] and wL[y] are calculated differently from embodiment A (i.e., equation (71) versus equation (102), equation (74) versus equation (105)). EXAMPLES

[0184] Embodiment C

[0185] Exemplary inputs to the PDPC filtering process include: · Intra prediction mode represented by preModeIntra; The width of the current block, expressed as nTbW; · the height of the current block, represented by nTbH; The width of the reference sample represented by refW; · the height of the reference sample represented by refH; · predicted samples represented by predSamples[x][y], where x = 0...nTbW-1, y = 0...nTbH-1; · Unfiltered reference (also called neighborhood) samples, denoted by p[x][y], where x=-1, y=-1…refH-1 and x=0…refW-1, y=-1; The color component of the current block represented by cIdx.

[0186] Depending on the value of cIdx, the function clip1Cmp is set as follows: If cIdx is equal to 0, clip1Cmp is Clip1 Y is set equal to; Otherwise, clip1Cmp is Clip1 C is set equal to

[0187] Furthermore, the output of the PDPC filtering process is the modified predicted samples predSamples'[x][y], x = 0...nTbW-1, y = 0...nTbH-1.

[0188] The scaling factor nScale can then be calculated according to equation (108).

number

[0189] Furthermore, a reference sample array mainRef[x], x = 0...refW may be defined as an array of unfiltered reference samples above the current block, and another reference sample array sideRef[y], y = 0...refH may be defined as an array of unfiltered reference samples to the left of the current block. The reference sample arrays mainRef[x] and sideRef[y] may be derived from the unfiltered reference samples according to equations (109)-(110), respectively.

number

[0190] For each position (x,y) in the current block, the PDPC calculation may use a reference sample at the top denoted as refT[x][y], a reference sample at the left denoted as refL[x][y], and a reference sample at the corner p[-1,-1]. In some examples, the modified predicted sample may be calculated according to equation (111), with the result suitably clipped according to a variable cIdx indicating the color component.

number

[0191] The reference samples refT[x][y], refL[x][y] and the weighting factors wL, wT and wTL may be determined based on the intra prediction mode preModeIntra.

[0192] When the intra prediction mode preModeIntra is equal to INTRA_PLANAR (e.g., 0, planar mode, or mode 0) or INTRA_DC (e.g., 1, DC mode, or mode 1), the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT and wTL may be determined according to equations (112) to (116).

number

[0193] Otherwise, if the intra prediction mode preModeIntra is equal to INTRA_ANGULAR18 (e.g., 18, horizontal mode, or mode 18) or INTRA_ANGULAR50 (e.g., 50, vertical mode, or mode 50), the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT and wTL may be determined according to equations (117) to (121).

number

[0194] Otherwise, if the intra-prediction mode preModeIntra is less than or equal to INTRA_ANGULAR10 (e.g., 10 or mode 10), then for each position (x, y), the variables dXInt[y] and dX[x][y] may be derived based on a variable invAngle, which is a function of the intra-prediction mode preModeIntra. invAngle may be determined based on a lookup table that stores corresponding invAngle values ​​for each intra-prediction mode, and then the reference samples refT[x][y], refL[x][y], and weighting factors wL, wT, and wTL may be determined based on the variables dXInt[y] and dX[x][y].

[0195] The variables dXInt[y] and dX[x][y] may be determined according to equations (122)-(123).

number

[0196] The reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL may then be determined according to equations (124)-(128).

number

[0197] Otherwise, if the intra-prediction mode preModeIntra is greater than or equal to INTRA_ANGULAR58 (e.g., 58, or mode 58), the variables dYInt[x] and dY[x][y] may be derived based on a variable invAngle, which is a function of the intra-prediction mode preModeIntra. invAngle may be determined based on a lookup table that stores corresponding invAngle values ​​for each intra-prediction mode, and then the reference samples refT[x][y], refL[x][y], and weighting factors wL, wT, and wTL may be determined based on the variables dYInt[x] and dY[x][y].

[0198] For example, the variables dYInt[x] and dY[x][y] may be determined according to equations (129)-(130).

number

[0199] The reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL may then be determined according to equations (131)-(135).

number

[0200] Otherwise, if the variable preModeIntra is between modes 11 and 57, and is neither mode 18 nor mode 50, then the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL are all set equal to 0.

[0201] Finally, the values ​​of the filtered samples filtSamples[x][y], x = 0...nTbW-1, y = 0...nTbH-1 may be derived according to equation (136).

number

[0202] The difference between embodiment B and embodiment C is that in embodiment C, when the intra prediction mode is INTRA_ANGULAR10 or less, dXPos[y] (equation (91)) is not calculated, and dXInt[y] may be calculated differently (i.e., equation (92) versus equation (122)). Similarly, when the intra prediction mode preModeIntra is INTRA_ANGULAR58 or more, in embodiment C, dYPos[x] (equation (99)) is not calculated, and dYInt[x] may be calculated differently (i.e., equation (100) versus equation (129)). EXAMPLES

[0203] Embodiment D

[0204] Exemplary inputs to the PDPC filtering process include: · Intra prediction mode represented by preModeIntra; The width of the current block, expressed as nTbW; · the height of the current block, represented by nTbH; The width of the reference sample represented by refW; · the height of the reference sample represented by refH; · predicted samples represented by predSamples[x][y], where x = 0...nTbW-1, y = 0...nTbH-1; · Unfiltered reference (also called neighborhood) samples, denoted by p[x][y], where x=-1, y=-1…refH-1 and x=0…refW-1, y=-1; The color component of the current block represented by cIdx.

[0205] Depending on the value of cIdx, the function clip1Cmp is set as follows: If cIdx is equal to 0, clip1Cmp is Clip1 Yis set equal to; Otherwise, clip1Cmp is Clip1 C is set equal to

[0206] Furthermore, the output of the PDPC filtering process is the modified predicted samples predSamples'[x][y], x = 0...nTbW-1, y = 0...nTbH-1.

[0207] The scaling factor nScale can then be calculated according to equation (137).

number

[0208] Furthermore, a reference sample array mainRef[x], x = 0...refW may be defined as an array of unfiltered reference samples above the current block, and another reference sample array sideRef[y], y = 0...refH may be defined as an array of unfiltered reference samples to the left of the current block. The reference sample arrays mainRef[x] and sideRef[y] may be derived from the unfiltered reference samples according to equations (138)-(139), respectively.

number

[0209] For each position (x,y) in the current block, the PDPC calculation may use the reference sample at the top, denoted as refT[x][y], the reference sample at the left, denoted as refL[x][y], and the reference sample at the corner, p[-1,-1]. The modified predicted sample may be calculated according to equation (140), with the result suitably clipped according to the variable cIdx indicating the color component.

number

[0210] The reference samples refT[x][y], refL[x][y] and the weighting factors wL, wT and wTL may be determined based on the intra prediction mode preModeIntra.

[0211] When the intra prediction mode preModeIntra is equal to INTRA_PLANAR (e.g., 0, planar mode, or mode 0) or INTRA_DC (e.g., 1, DC mode, or mode 1), the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT and wTL may be determined according to equations (141) to (145).

number

[0212] Otherwise, if the intra prediction mode preModeIntra is equal to INTRA_ANGULAR18 (e.g., 18, horizontal mode, or mode 18) or INTRA_ANGULAR50 (e.g., 50, vertical mode, or mode 50), the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT and wTL may be determined according to equations (146) to (150).

number

[0213] Otherwise, if the intra-prediction mode preModeIntra is equal to INTRA_ANGULAR2 (e.g., 2 or mode 2), then for each position (x, y), the variables dXPos[y], dXFrac[y], dXInt[y], and dX[x][y] may be derived based on a variable invAngle, which is a function of the intra-prediction mode preModeIntra. invAngle may be determined based on a lookup table that stores corresponding invAngle values ​​for each intra-prediction mode, and then the reference samples refT[x][y], refL[x][y], and weighting factors wL, wT, and wTL may be determined based on the variables dXPos[y], dXFrac[y], dXInt[y], and dX[x][y].

[0214] The variables dXPos[y], dXFrac[y], dXInt[y], and dX[x][y] may be determined according to equations (151)-(154).

number

[0215] The reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL may then be determined according to equations (155)-(159).

number

[0216] Otherwise, if the intra-prediction mode preModeIntra is less than or equal to INTRA_ANGULAR10 (e.g., 10 or mode 10), then for each position (x, y), the variables dXPos[y], dXFrac[y], dXInt[y], and dX[x][y] may be derived based on a variable invAngle, which is a function of the intra-prediction mode preModeIntra. invAngle may be determined based on a lookup table that stores corresponding invAngle values ​​for each intra-prediction mode, and then the reference samples refT[x][y], refL[x][y], and weighting factors wL, wT, and wTL may be determined based on the variables dXPos[y], dXFrac[y], dXInt[y], and dX[x][y].

[0217] The variables dXPos[y], dXFrac[y], dXInt[y], and dX[x][y] may be determined according to equations (160)-(163).

number

[0218] The reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL may then be determined according to equations (164)-(168).

number

[0219] Otherwise, if the intra-prediction mode preModeIntra is equal to INTRA_ANGULAR66 (e.g., 66, or mode 66), the variables dYPos[x], dYFrac[x], dYInt[x], and dY[x][y] may be derived based on a variable invAngle, which is a function of the intra-prediction mode preModeIntra. invAngle may be determined based on a lookup table that stores corresponding invAngle values ​​for each intra-prediction mode, and then the reference samples refT[x][y], refL[x][y], and weighting factors wL, wT, and wTL may be determined based on the variables dYPos[x], dYFrac[x], dYInt[x], and dY[x][y].

[0220] The variables dYPos[x], dYFrac[x], dYInt[x], and dY[x][y] may be determined according to equations (169)-(172).

number

[0221] The reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL may then be determined according to equations (173)-(177).

number

[0222] Otherwise, if the intra-prediction mode preModeIntra is greater than or equal to INTRA_ANGULAR58 (e.g., 58, or mode 58), the variables dYPos[x], dYFrac[x], dYInt[x], and dY[x][y] may be derived based on a variable invAngle, which is a function of the intra-prediction mode preModeIntra. invAngle may be determined based on a lookup table that stores corresponding invAngle values ​​for each intra-prediction mode, and then the reference samples refT[x][y], refL[x][y], and weighting factors wL, wT, and wTL may be determined based on the variables dYPos[x], dYFrac[x], dYInt[x], and dY[x][y].

[0223] For example, the variables dYPos[x], dYFrac[x], dYInt[x], and dY[x][y] may be determined according to equations (178)-(181).

number

[0224] The reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL may then be determined according to equations (182)-(186).

number

[0225] Otherwise, if the variable preModeIntra is between modes 11 and 57, and is neither mode 18 nor mode 50, then the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL are all set equal to 0.

[0226] Finally, the values ​​of the filtered samples filtSamples[x][y], x = 0...nTbW-1, y = 0...nTbH-1 may be derived according to equation (187).

number

[0227] Embodiment D is similar to embodiment A, but describes a different modified PDPC process for mode 2 and mode 66. EXAMPLES

[0228] Embodiment E

[0229] Exemplary inputs to the PDPC filtering process include the following: · Intra prediction mode represented by preModeIntra; The width of the current block, expressed as nTbW; · the height of the current block, represented by nTbH; The width of the reference sample represented by refW; · the height of the reference sample represented by refH; · predicted samples represented by predSamples[x][y], where x = 0...nTbW-1, y = 0...nTbH-1; · Unfiltered reference (also called neighborhood) samples, denoted by p[x][y], where x=-1, y=-1…refH-1 and x=0…refW-1, y=-1; The color component of the current block represented by cIdx.

[0230] Depending on the value of cIdx, the function clip1Cmp is set as follows: If cIdx is equal to 0, clip1Cmp is Clip1 Y is set equal to; Otherwise, clip1Cmp is Clip1 C is set equal to

[0231] Furthermore, the output of the PDPC filtering process is the modified predicted samples predSamples'[x][y], x = 0...nTbW-1, y = 0...nTbH-1.

[0232] The scaling factor nScale can then be calculated according to equation (188).

number

[0233] Furthermore, a reference sample array mainRef[x], x = 0...refW may be defined as an array of unfiltered reference samples above the current block, and another reference sample array sideRef[y], y = 0...refH may be defined as an array of unfiltered reference samples to the left of the current block. The reference sample arrays mainRef[x] and sideRef[y] may be derived from the unfiltered reference samples according to equations (189)-(190), respectively.

number

[0234] For each position (x,y) in the current block, the PDPC calculation may use a reference sample at the top denoted as refT[x][y], a reference sample at the left denoted as refL[x][y], and a reference sample at the corner p[-1,-1]. In some examples, the modified predicted sample may be calculated according to equation (191), with the result suitably clipped according to a variable cIdx indicating the color component.

number

[0235] The reference samples refT[x][y], refL[x][y] and the weighting factors wL, wT and wTL may be determined based on the intra prediction mode preModeIntra.

[0236] When the intra prediction mode preModeIntra is equal to INTRA_PLANAR (e.g., 0, planar mode, or mode 0) or INTRA_DC (e.g., 1, DC mode, or mode 1), the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT and wTL may be determined according to equations (192) to (196).

number

[0237] Otherwise, if the intra prediction mode preModeIntra is equal to INTRA_ANGULAR18 (e.g., 18, horizontal mode, or mode 18) or INTRA_ANGULAR50 (e.g., 50, vertical mode, or mode 50), the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT and wTL may be determined according to equations (197) to (201).

number

[0238] Otherwise, if the intra-prediction mode preModeIntra is less than or equal to INTRA_ANGULAR10 (e.g., 10 or mode 10), then for each position (x, y), the variables dXInt[y] and dX[x][y] may be derived based on a variable invAngle, which is a function of the intra-prediction mode preModeIntra. invAngle may be determined based on a lookup table that stores corresponding invAngle values ​​for each intra-prediction mode, and then the reference samples refT[x][y], refL[x][y], and weighting factors wL, wT, and wTL may be determined based on the variables dXInt[y] and dX[x][y].

[0239] For example, the variables dXInt[y] and dX[x][y] may be determined according to equations (202)-(203).

number

[0240] The reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL may then be determined according to equations (204)-(208).

number

[0241] Otherwise, if the intra-prediction mode preModeIntra is greater than or equal to INTRA_ANGULAR58 (e.g., 58, or mode 58), the variables dYInt[x] and dY[x][y] may be derived based on a variable invAngle, which is a function of the intra-prediction mode preModeIntra. invAngle may be determined based on a lookup table that stores corresponding invAngle values ​​for each intra-prediction mode, and then the reference samples refT[x][y], refL[x][y], and weighting factors wL, wT, and wTL may be determined based on the variables dYInt[x] and dY[x][y].

[0242] For example, the variables dYInt[x] and dY[x][y] may be determined according to equations (209)-(210).

number

[0243] The reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL may then be determined according to equations (211)-(215).

number

[0244] Otherwise, if the variable preModeIntra is between modes 11 and 57, and is neither mode 18 nor mode 50, then the reference samples refT[x][y], refL[x][y], and the weighting factors wL, wT, and wTL are all set equal to 0.

[0245] Finally, the values ​​of the filtered samples filtSamples[x][y], x = 0...nTbW-1, y = 0...nTbH-1 may be derived according to equation (216).

number

[0246] The difference between embodiment C and embodiment E is that in embodiment E, refT[x][y] may be calculated differently (i.e., equation (125) versus equation (205)) when the intra prediction mode is equal to or less than INTRA_ANGULAR10. Similarly, refL[x][y] may be calculated differently (i.e., equation (131) versus equation (211)) when the intra prediction mode preModeIntra is equal to or greater than INTRA_ANGULAR58.

[0247] Early termination of the PDPC process

[0248] According to an embodiment of the present disclosure, for intra prediction modes adjacent to diagonal intra prediction modes, such as modes -1 to -14, modes 3 to 10, modes 58 to 65, and modes 67 to 80 in FIG. 8A, the PDPC process may have an early termination, where the early termination depends on the fractional position to which the intra prediction direction points on the lateral reference samples used in the PDPC process.

[0249] In one embodiment, the assignment of reference sample values ​​used in the PDPC process is modified as follows.

[0250] For intra prediction modes adjacent to mode 2, equation (30) is modified as equation (217).

number

[0251] For intra prediction modes adjacent to mode 66, equation (38) is modified as equation (218).

number

[0252] Reference Sample Testing

[0253] In some related embodiments (e.g., in VVC), a sample-by-sample check is required for a current sample in the PDPC process to determine whether the current sample's reference sample is within a specified range. If the reference sample is not within the specified range, the PDPC weighting factor is set to 0 for the current sample, e.g., as described in Equation (30), Equation (31), Equation (38), and Equation (41). However, this sample-by-sample check may be undesirable, especially for software optimizations that use Single Instruction Multiple Data (SIMD) techniques.

[0254] According to some embodiments, the sample-by-sample check in the PDPC process used to determine whether a reference sample is within the range of available reference samples is replaced by a row-by-row or column-by-column check. In one embodiment, the check condition depends only on the number of available left reference samples, the predicted block height, and the horizontal coordinate value of the current sample to be filtered by the PDPC process. In another embodiment, the check condition depends only on the number of available above reference samples, the predicted block width, and the vertical coordinate value of the current sample to be filtered by the PDPC process.

[0255] In one embodiment, in the case of vertical-like intra prediction (i.e., the prediction direction is closer to the vertical intra prediction direction than the horizontal prediction direction), the check is performed column-wise and the check condition depends only on at least one of the number of available left reference samples, the predicted block height, and the horizontal coordinate value of the current sample filtered by the PDPC process.

[0256] In one embodiment, in the case of horizontal-like intra prediction (i.e., the prediction direction is closer to the horizontal intra prediction direction than the vertical prediction direction), the check is performed row-by-row and the check condition depends only on at least one of the number of available reference samples above, the prediction block width, and the vertical coordinate value of the current sample filtered by the PDPC process.

[0257] According to some embodiments, the PDPC process may be configured such that the intra prediction angle of the intra prediction mode is 2 k It is applied to intra prediction modes if k is greater than or equal to a preset value such as k / 32, where k is a non-negative integer such as 3 or 4.

[0258] In one embodiment, in the case of vertical-like intra prediction (i.e., the prediction direction is closer to the vertical intra prediction direction than the horizontal prediction direction), the first (width / (2 5-k ))(or min(width,height) / (2 5-k )) columns are processed by the PDPC process.

[0259] In one embodiment, for horizontal-like intra prediction (i.e., the prediction direction is closer to the horizontal intra prediction direction than the vertical prediction direction), the first (height / (2 5-k ))(or min(width,height) / (2 5-k )) rows are processed by the PDPC process.

[0260] FIG. 10 shows a flow chart outlining an example process (1000) according to an embodiment of the present disclosure. In various embodiments, the process (1000) is performed by processing circuitry within the terminal devices (210), (220), (230), and (240), a processing circuitry performing the functionality of the video encoder (303), a processing circuitry performing the functionality of the video decoder (310), a processing circuitry performing the functionality of the video decoder (410), a processing circuitry performing the functionality of the intra prediction module (452), a processing circuitry performing the functionality of the video encoder (503), a processing circuitry performing the functionality of the predictor (535), a processing circuitry performing the functionality of the intra encoder (622), a processing circuitry performing the functionality of the intra decoder (772), or the like. In some embodiments, the process (1000) is implemented with software instructions, such that the processing circuitry performs the process (1000) when the processing circuitry executes the software instructions.

[0261] The process (1000) may generally begin at step (S1010), where the process (1000) decodes prediction information for a current block in a current picture that is part of a coded video sequence. The prediction information indicates an intra-prediction direction for the current block, which is one of (i) a diagonal intra-prediction direction, or (ii) a neighboring intra-prediction direction adjacent to the diagonal intra-prediction direction. The process (1000) then proceeds to step (S1020).

[0262] In step (S1020), the process (1000) determines the use of a position-dependent prediction combining (PDPC) process according to the intra-prediction direction of the current block. The same PDPC process is applied to both the diagonal intra-prediction direction and the neighboring intra-prediction direction. Then, the process (1000) proceeds to step (S1030).

[0263] In step S1030, the process 1000 reconstructs the current block based on the use of the PDPC process for the current block.

[0264] After reconstructing the current block, the process (1000) ends.

[0265] In some embodiments, the diagonal intra prediction direction is one of a bottom-left prediction direction and a top-right prediction direction. In an embodiment, if the diagonal intra prediction direction is a bottom-left intra prediction direction, the mode index of the neighboring intra prediction direction is below the mode index of the horizontal intra prediction direction. In an embodiment, if the diagonal intra prediction direction is a top-right intra prediction direction, the mode index of the neighboring intra prediction direction is above the mode index of the vertical intra prediction direction.

[0266] In one embodiment, if the intra prediction direction is a neighboring intra prediction direction, the process (1000) determines whether the intra prediction direction points to a fractional position. In response to determining that the intra prediction points to a fractional position, the process (1000) determines an early termination of the PDPC process.

[0267] In some embodiments, when a current sample in a current block is filtered by the PDPC process, the process (1000) determines whether the reference sample of the current sample is located within a preset range according to a row-by-row check or a column-by-column check. In one embodiment, the column-by-column check depends on at least one of (i) the total number of available reference samples located to the left of the current block, (ii) the block height of the current block, and (iii) the horizontal coordinate value of the current sample. In one embodiment, the row-by-row check depends on at least one of (i) the total number of available reference samples located above the current block, (ii) the block width of the current block, and (iii) the vertical coordinate value of the current sample.

[0268] In some embodiments, the angle of the intra prediction direction is equal to or greater than a preset value. In one embodiment, if the intra prediction direction is closer to the vertical intra prediction direction than the horizontal intra prediction direction, the process (1000) performs a PDPC process on a first number of columns of samples in the current block, the first number being determined according to the preset value and the block size of the current block. In one embodiment, if the intra prediction direction is closer to the horizontal intra prediction direction than the vertical intra prediction direction, the process (1000) performs a PDPC process on a second number of rows of samples in the current block, the second number being determined according to the preset value and the block size of the current block.

[0269] The techniques described above can be implemented as computer software using computer-readable instructions and can be physically stored on one or more computer-readable media. For example, Figure 11 illustrates a computer system (1100) suitable for implementing certain embodiments of the disclosed subject matter.

[0270] Computer software may be coded using any suitable machine code or computer language and may be subject to assembly, compilation, linking, or similar mechanisms to produce code containing instructions that are executable by one or more computer central processing units (CPUs), graphics processing units (GPUs), etc., either directly, or through interpretation, microcode execution, etc.

[0271] The instructions may be executed on various types of computers or components thereof including, for example, personal computers, tablet computers, servers, smart phones, gaming devices, Internet of Things devices, and the like.

[0272] 11 for computer system (1100) are exemplary in nature and are not intended to suggest any limitation as to the scope of use or functionality of the computer software implementing the embodiments of the present disclosure, nor should the arrangement of components be interpreted as having any dependency or requirement regarding any one or combination of components illustrated in the exemplary embodiment of computer system (1100).

[0273] The computer system (1100) may include certain human interface input devices that may be responsive to input by one or more human users through, for example, tactile input (e.g., keystrokes, swipes, data glove movements), audio input (e.g., voice, clapping), visual input (e.g., gestures), and olfactory input (not shown). Human interface devices may also be used to capture certain media that are not necessarily directly related to conscious human input, such as audio (e.g., speech, music, ambient sounds), images (e.g., scanned images, photographic images obtained from still image cameras), and video (e.g., two-dimensional video, three-dimensional video including stereoscopic video).

[0274] The input human interface devices may include one or more (only one of each is shown) of a keyboard (1101), a mouse (1102), a trackpad (1103), a touch screen (1110), a data glove (not shown), a joystick (1105), a microphone (1106), a scanner (1107), and a camera (1108).

[0275] The computer system (1100) may also include some type of human interface output device. Such human interface output devices may stimulate one or more of the human user's senses, for example, through haptic output, sound, light, and smell / taste. Such human interface output devices may include haptic output devices (e.g., haptic feedback via a touch screen (1110), data gloves (not shown), or joystick (1105); although there may be haptic feedback devices that do not act as input devices), audio output devices (e.g., speakers (1109), headphones (not shown)), visual output devices (e.g., screens (1110) including CRT screens, LCD screens, plasma screens, OLED screens; each may or may not have touch screen input capability, each may or may not have haptic feedback capability, some of which may output two-dimensional visual output or higher than three-dimensional output through means such as stereoscopic output; virtual reality glasses (not shown), holographic displays, and smoke tanks (not shown)), and printers (not shown). These output devices (such as a screen (1110)) can be connected to the system bus (1148) through a graphics adapter (1150).

[0276] The computer system (1100) may also include human accessible storage and associated media, such as optical media including CD / DVD ROM / RW (1120) along with CD / DVD or similar media (1121), thumb drives (1122), removable hard drives or solid state drives (1123), legacy magnetic media such as tapes and floppy disks (not shown), specialized ROM / ASIC / PLD based devices such as security dongles (not shown), etc.

[0277] Those skilled in the art should also understand that the term "computer-readable medium" as used in connection with the presently disclosed subject matter does not encompass transmission media, carrier waves, or other transitory signals.

[0278] The computer system (1100) may also include a network interface (1154) to one or more communication networks (1155). The one or more communication networks (1155) may be, for example, wireless, wired, optical. The one or more communication networks (1155) may further be local, wide area, metropolitan, in-vehicle and industrial, real-time, delay tolerant, etc. Examples of the one or more communication networks (1155) include cellular networks including Ethernet, WLAN, GSM, 3G, 4G, 5G, LTE, etc., TV wired or wireless wide area digital networks including cable television, satellite television, terrestrial broadcast television, in-vehicle and industrial including CANBus, etc. Some networks usually require an external network interface adapter to be attached to some kind of general-purpose data port or peripheral bus (1149) (e.g., a USB port of the computer system (1100)). Others are typically integrated into the core of the computer system (1100) by attachment to a system bus as described below (e.g., an Ethernet interface to a PC computer system or a cellular network interface to a smartphone computer system). Using any of these networks, the computer system (1100) can communicate with other entities. Such communications may be unidirectional, receive only (e.g., broadcast television), unidirectional transmit only (e.g., CANbus to certain CANbus devices), or bidirectional, for example, to other computer systems using local or wide area digital networks. With each of these networks and network interfaces as described above, certain protocols and protocol stacks may be used.

[0279] The aforementioned human interface devices, human accessible storage devices, and network interfaces may be attached to a core (1140) of the computer system (1100).

[0280] The core (1140) may include one or more central processing units (CPUs) (1141), graphics processing units (GPUs) (1142), specialized programmable processing units in the form of field programmable gate arrays (FPGAs) (1143), hardware accelerators for certain tasks (1144), and the like. These devices may be connected through a system bus (1148), along with read only memory (ROM) (1145), random access memory (1146), and internal mass storage devices (1147), such as internal non-user accessible hard drives, solid state drives (SSDs), and the like. In some computer systems, the system bus (1148) may be accessible in the form of one or more physical plugs to allow expansion with additional CPUs, GPUs, and the like. Peripheral devices may be attached directly to the core's system bus (1148) or through a peripheral bus (1149). Architectures for peripheral buses include PCI, USB, and the like.

[0281] The CPU (1141), GPU (1142), FPGA (1143), and accelerator (1144) can execute certain instructions that, in combination, may constitute the computer code described above. The computer code may be stored in a ROM (1145) or a RAM (1146). Temporary data may also be stored in the RAM (1146), while persistent data may be stored, for example, in an internal mass storage device (1147). Rapid storage and retrieval in any of the memory devices may be enabled through the use of a cache memory that may be closely associated with one or more of the CPU (1141), GPU (1142), mass storage device (1147), ROM (1145), RAM (1146), etc.

[0282] The computer-readable medium can have computer code thereon for performing various computer-implemented operations. The medium and computer code may be those specially designed and constructed for the purposes of the present disclosure, or they may be of the kind well known and available to those having skill in the computer software arts.

[0283] By way of example and not limitation, the architecture (1100), and in particular a computer system having a core (1140), can provide functionality as a result of a processor (including a CPU, GPU, FPGA, accelerator, etc.) executing software embodied in one or more tangible computer readable media. Such computer readable media can be user accessible mass storage as introduced above as well as media associated with some type of storage of the core (1140) of a non-transitory nature such as mass storage (1147) internal to the core or ROM (1145). Software implementing various embodiments of the present disclosure can be stored in such devices and executed by the core (1140). The computer readable media can include one or more memory devices or chips depending on the particular needs. The software can cause the core (1140) and in particular the processors therein (including a CPU, GPU, FPGA, etc.) to execute certain processes or certain specific portions thereof described herein, including defining data structures stored in RAM (1146) and modifying such data structures according to processes defined by the software. Additionally or alternatively, the computer system may provide functionality as a result of logic hardwired or otherwise embodied in circuitry (e.g., accelerator (1144)), which may operate in place of or together with software to perform particular processes or portions of particular processes described herein. Reference to software includes logic, and vice versa, as appropriate. Reference to a computer-readable medium may encompass circuitry (e.g., an integrated circuit (IC)) that stores software for execution, circuitry that embodies logic for execution, or both, as appropriate. The present disclosure encompasses any suitable combination of hardware and software.

[0284] While this disclosure has described several exemplary embodiments, there are alterations, substitutions, and various substitute equivalents, which fall within the scope of this disclosure. Thus, it will be appreciated that those skilled in the art will be able to devise many systems and methods that, although not explicitly shown or described herein, embody the principles of the present disclosure and are thus within the spirit and scope of the present disclosure.

[0285] Appendix A: Acronyms AMVP: Advanced Motion Vector Prediction ASIC: Application-Specific Integrated Circuit ATMVP: Alternative / Advanced Temporal Motion Vector Prediction BDOF: Bi-directional Optical Flow BIO: Bi-directional Optical Flow BMS:Benchmark Set BV: Block Vector CANBus: Controller Area Network Bus CB: Coding Block CBF: Coded Block Flag CCLM: Cross-Component Linear Mode / Model CD: Compact Disc CPR: Current Picture Referencing CPU: Central Processing Unit CRT:Cathode Ray Tube CTB: Coding Tree Block CTU: Coding Tree Units CU: Coding Unit DPB: Decoder Picture Buffer DVD: Digital Video Disc FPGA: Field Programmable Gate Area GOP: Group of Pictures GPU: Graphics Processing Unit GSM: Global System for Mobile communications HDR: High Dynamic Range HEVC: High Efficiency Video Coding HRD: Hypothetical Reference Decoder IBC: Intra Block Copy IC: Integrated Circuit ISP: Intra Sub-Partitions JEM: Joint Exploration Model JVET: Joint Video Exploration Team LAN: Local Area Network LCD: Liquid-Crystal Display LTE: Long-Term Evolution MPM: Most Probable Mode MTS: Multiple Transform Selection MV: Motion Vector OLED: Organic Light-Emitting Diode PB: Prediction Blocks PCI: Peripheral Component Interconnect PDPC: Position Dependent Prediction Combination PLD: Programmable Logic Device PU: Prediction Unit RAM: Random Access Memory ROM: Read-Only Memory SBT: Sub-block Transform SCC: Screen Content Coding SDR: Standard Dynamic Range SEI: Supplementary Enhancement Information SNR: Signal Noise Ratio SSD: Solid-state drive TU: Transform Unit USB: Universal Serial Bus VPDU: Visual Process Data Unit VUI: Video Usability Information VVC:Versatile Video Coding WAIP: Wide-Angle Intra Prediction

Claims

[Claim 1] 1. A method of video decoding performed by a decoder, the method comprising: decoding prediction information for a current block in a current picture that is part of a coded video sequence, the prediction information indicating an intra-prediction direction for the current block that is one of (i) a diagonal intra-prediction direction, or (ii) a neighboring intra-prediction direction that is adjacent to the diagonal intra-prediction direction; determining a usage of a position-dependent prediction combining (PDPC) process according to an intra prediction direction of a current block, where the same PDPC process is applied to both diagonal and neighboring intra prediction directions; Reconstructing the current block based on use of a PDPC process for the current block, the PDPC process comprising: if the intra prediction direction is closer to the vertical intra prediction direction than the horizontal intra prediction direction, then it is performed on a first number of columns of samples in the current block; and if the intra prediction direction is closer to the horizontal intra prediction direction than to the vertical intra prediction direction, for a second number of rows of samples in the current block. method.

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