CN112073720B - Method and apparatus for video decoding, computer device and storage medium - Google Patents

Abstract

Embodiments of the present application provide a method and apparatus for video decoding, a computer device, and a storage medium. The method comprises the following steps: decoding prediction information for a current block in a current picture, the current picture being part of an encoded video sequence, the prediction information indicating an intra-prediction direction for the current block, the intra-prediction direction being one of a diagonal intra-prediction direction and an adjacent intra-prediction direction that is adjacent to the diagonal intra-prediction direction; determining to use a Position Dependent Prediction Combining (PDPC) process according to the intra prediction direction of the current block, wherein the same PDPC process is applied to the diagonal intra prediction direction and the neighboring intra prediction direction; and reconstructing the current block based on the PDPC process used on the current block.

Description

Method and apparatus for video decoding, computer device and storage medium

Incorporated herein by reference

The present application claims priority from U.S. provisional application No. 62/859,920 entitled "unified location-related predictive combining procedure" filed on 11.6.2019, U.S. provisional application No. 62/869,015 entitled "further unification of location-related predictive combining procedures" filed on 30.6.2019, and U.S. application No. 15/931,225 entitled "unified location-related predictive combining procedure" filed on 13.5.2020, the entire contents of which are incorporated herein by reference.

Technical Field

The present application relates to video encoding and decoding techniques. In particular, the present application relates to a method and apparatus for video decoding, a computer device and a storage medium.

Background

Video encoding and decoding may be performed by an inter-picture prediction technique with motion compensation. Uncompressed digital video may comprise a series of pictures, each picture having spatial dimensions of, for example, 1920x1080 luma samples and related chroma samples. The series of pictures has a fixed or variable picture rate (also informally referred to as frame rate), e.g. 60 pictures per second or 60 Hz. Uncompressed video has very large bit rate requirements. For example, 1080p 604: 2:0 video (1920x1080 luminance sample resolution, 60Hz frame rate) with 8 bits per sample requires close to 1.5Gbit/s bandwidth. One hour of such video requires more than 600GB of storage space.

One purpose of video encoding and decoding is to reduce redundant information of an input video signal by compression. Video compression can help reduce the bandwidth or storage requirements described above, by two or more orders of magnitude in some cases. Lossless and lossy compression, as well as combinations of both, may be employed. Lossless compression refers to a technique for reconstructing an exact copy of an original signal from a 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 signal and the reconstructed signal is small enough that the reconstructed signal is useful for the intended application. Lossy compression is widely used for video. The amount of distortion tolerated depends on the application. For example, some users consuming streaming media applications may tolerate higher distortion than users of television applications. The achievable compression ratio reflects: higher allowable/tolerable distortion may result in higher compression ratios.

Video encoders and decoders may utilize several broad classes of techniques, including, for example: motion compensation, transformation, quantization and entropy coding.

The video codec techniques may include known intra-coding techniques. In intra coding, sample values are represented without reference to samples or other data of a previously reconstructed reference picture. In some video codecs, a picture is spatially subdivided into blocks of samples. When all sample blocks are encoded in intra mode, the picture may be an intra picture. Intra pictures and their derivatives (e.g., independent decoder refresh pictures) can be used to reset the decoder state and thus can be used as the first picture in an encoded video bitstream and video session, or as still images. Samples of the intra block may be used for the transform, and the transform coefficients may be quantized prior to entropy encoding. Intra prediction may be a technique that minimizes sample values in the pre-transform domain. In some cases, the smaller the transformed DC value and the smaller the AC coefficient, the fewer bits are needed to represent the block after entropy coding at a given quantization step size.

As is known from techniques such as MPEG-2 generation coding, conventional intra-frame coding does not use intra-prediction. However, some newer video compression techniques include: techniques are attempted to derive data chunks from, for example, surrounding sample data and/or metadata obtained during spatially adjacent encoding/decoding and prior to the decoding order. This technique was later referred to as an "intra-prediction" technique. It is noted that, at least in some cases, intra prediction uses only the reference data of the current picture being reconstructed, and not the reference data of the reference picture.

There may be many different forms of intra prediction. When more than one such technique may be used in 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, and these modes may be encoded separately or included in a mode codeword. Which codeword is used for a given mode/sub-mode/parameter combination affects the coding efficiency gain through intra prediction, and so does the entropy coding technique used to convert the codeword into a bitstream.

Disclosure of Invention

Embodiments of the present application provide a method and apparatus for video decoding, a computer device, and a storage medium, which aim to solve the problems in the prior art that no significant benefit is obtained when different PDPC processes are applied to an intra-coded block having a diagonal intra-prediction mode and its neighboring modes because the prediction processes of the diagonal prediction mode and its neighboring modes are similar, and in the prior art, each sample needs to be checked to determine whether a reference sample of a current sample is within a specified range, thereby causing a reduction in decoding efficiency.

According to an embodiment of the present application, a method of video decoding is provided. The method comprises the following steps:

Decoding prediction information for a current block in a current picture, the current picture being part of an encoded video sequence, the prediction information indicating an intra-prediction direction for the current block, the intra-prediction direction being one of a diagonal intra-prediction direction and an adjacent intra-prediction direction that is adjacent to the diagonal intra-prediction direction;

determining a PDPC process using a position dependent prediction combination according to the intra prediction direction of the current block, wherein the PDPC process used when the intra prediction direction is the diagonal intra prediction direction is the same as the PDPC process used when the intra prediction direction is the neighboring intra prediction direction; and

reconstructing the current block based on the PDPC process used on the current block.

According to an embodiment of the present application, there is provided an apparatus for video decoding. The device includes:

a decoding module to decode prediction information for a current block in a current picture, the current picture being part of an encoded video sequence, the prediction information indicating an intra-prediction direction for the current block, the intra-prediction direction being one of a diagonal intra-prediction direction and an adjacent intra-prediction direction adjacent to the diagonal intra-prediction direction;

A determination module for determining a PDPC process using a position dependent prediction combination according to the intra prediction direction of the current block, wherein the PDPC process used when the intra prediction direction is the diagonal intra prediction direction is the same as the PDPC process used when the intra prediction direction is the neighboring intra prediction direction; and

a reconstruction module to reconstruct the current block based on the PDPC process used on the current block.

Embodiments of the present application also provide a non-transitory computer-readable medium storing program instructions that, when executed by a computer for video encoding/decoding, cause the computer to perform the method of video decoding.

Embodiments of the present application also provide a computer device comprising one or more processors and one or more memories having stored therein at least one program instruction, the at least one program instruction being loaded and executed by the one or more processors to implement the method of video decoding.

In the embodiment of the present application, by modifying the PDPC process, different PDPC processes can be applied to an intra-coded block having a diagonal intra-prediction mode and its neighboring intra-prediction modes, and it is possible to determine whether a reference sample of a current sample is within a specified range without checking each sample, thereby improving decoding efficiency.

Drawings

Other features, properties, and various advantages of the disclosed subject matter will be further apparent from the following detailed description and the accompanying drawings, in which:

FIG. 1A shows a schematic diagram of an exemplary subset of intra prediction modes;

FIG. 1B shows a diagram of exemplary intra prediction directions;

FIG. 1C is a diagram illustrating a current block and its surrounding spatial merge candidates in one example;

FIG. 2 shows a schematic diagram of a simplified block diagram of a communication system according to an embodiment;

FIG. 3 shows a schematic diagram of a simplified block diagram of a communication system according to another embodiment;

FIG. 4 shows a schematic diagram of a simplified block diagram of a decoder according to an embodiment;

FIG. 5 shows a schematic diagram of a simplified block diagram of an encoder according to an embodiment;

FIG. 6 shows a block diagram of an encoder according to another embodiment;

FIG. 7 shows a block diagram of a decoder according to another embodiment;

fig. 8A illustrates a schematic diagram of exemplary intra prediction directions and corresponding intra prediction modes in some examples (e.g., VVC);

fig. 8B shows a list of angular intra prediction modes and their corresponding intra prediction angles in some examples (e.g., VVC);

fig. 9A shows exemplary weighting factors for a prediction sample at (0, 0) in DC mode according to an embodiment;

Fig. 9B shows exemplary weighting factors for the prediction samples at (1, 0) in DC mode according to an embodiment;

fig. 10 shows a flowchart outlining an exemplary process of a video decoding method according to an embodiment of the present application.

Fig. 11 is a schematic diagram of a computer system, according to an embodiment.

Detailed Description

H.264 introduces an intra prediction mode that is improved in h.265 and further improved in newer coding techniques such as joint development model (JEM)/universal video coding (VVC)/reference set (BMS). A prediction block may be formed by using neighboring sample values belonging to already available samples. In some examples, sample values of neighboring samples are copied into a prediction block in a certain direction. The reference to the direction used may be encoded in the bitstream or may itself be predicted.

Referring to fig. 1A, the bottom right depicts a subset of nine prediction directions known from the 33 possible prediction directions of h.265 (33 angular modes corresponding to 35 intra modes). The point (101) where the arrows converge represents the sample being predicted. The arrows indicate the direction in which the samples are being predicted. For example, arrow (102) represents the prediction of a sample (101) from one or more samples at an angle of 45 degrees to the horizontal from the upper right. Similarly, arrow (103) represents the prediction of a sample (101) from one or more samples at an angle of 22.5 degrees to the horizontal at the bottom left.

Still referring to fig. 1A, a square block (104) comprising 4 x 4 samples is shown at the top left (indicated by the thick dashed line). The square block (104) includes 16 samples, each labeled with "S", and its position in the Y dimension (e.g., row index) and its position in the X dimension (e.g., column index). For example, sample S21 is the second sample in the Y dimension (starting from the top) and the first sample in the X dimension (starting from the left). Similarly, sample S44 is the fourth sample in the block (104) in both the Y dimension and the X dimension. Since the block is a 4 × 4 sample size, S44 is located at the lower right corner. Reference samples following a similar numbering scheme are also shown. The reference sample is labeled with R, and its Y position (e.g., row index) and X position (e.g., column index) relative to the block (104). In h.264 and h.265, the prediction samples are adjacent to the block being reconstructed, so negative values need not be used.

Intra picture prediction can be performed by copying the reference sample values from the neighbouring samples occupied by the signaled prediction direction. For example, assume that the encoded video bitstream includes signaling indicating, for the block, a prediction direction that coincides with the arrow (102), i.e. samples are predicted from one or more predicted samples whose upper right is at a 45 degree angle to the horizontal direction. In this case, samples S41, S32, S23, and S14 are predicted from the same reference sample R05. Then, a sample S44 is predicted from the reference sample R08.

In some cases, the values of multiple reference samples may be combined, for example by interpolation, to calculate the reference sample, especially when the direction is not evenly divisible by 45 degrees.

As video coding techniques have evolved, the number of possible directions has increased. In h.264 (2003), nine different directions can be represented. There are 33 increases in H.265 (2013) and JEM/VVC/BMS, and up to 65 orientations can be supported at the time of this application. Experiments have been performed to identify the most likely directions and some techniques in entropy coding are used to represent those possible directions using a small number of bits, accepting some cost for less likely directions. Furthermore, sometimes the direction itself can be predicted from the neighboring directions used in neighboring, already decoded blocks.

Fig. 1B shows a schematic diagram (105) depicting 65 intra prediction directions according to JEM to illustrate the increase in the number of prediction directions over time.

The mapping of intra prediction direction bits in the coded video bitstream representing directions may differ from one video coding technique to another and may for example range from a simple direct mapping of intra prediction modes to prediction directions of codewords to a complex adaptation scheme including most probable modes and similar techniques. In all cases, however, there may be certain directions in the video content that are statistically less likely to occur than other directions. Since the goal of video compression is to reduce redundancy, in well-functioning video coding techniques, those unlikely directions will be represented using a greater number of bits than the more likely directions.

Motion compensation may be a lossy compression technique and may involve the following: sample data blocks from a previously reconstructed picture or a portion of a reconstructed picture (reference picture) are spatially shifted in the direction indicated by a motion vector (hereinafter MV) and used for prediction of the newly reconstructed picture or portion of the picture. 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, where the third dimension represents the reference picture in use (the latter may be indirectly the temporal dimension).

In some video compression techniques, an MV applied to a certain sample data region may be predicted from other MVs, e.g., from those MVs that are related to another sample data region spatially adjacent to the region being reconstructed and that precede the MV in decoding order. This can greatly reduce the amount of data required to encode the MV, thereby eliminating redundant information and increasing the amount of compression. MV prediction can be performed efficiently, for example, when encoding an input video signal derived from a camera (referred to as natural video), there is a statistical possibility that regions having areas larger than a single MV applicable region will move in similar directions, and thus prediction can be performed using similar motion vectors derived from MVs of adjacent regions in some cases. This results in the MVs found for a given region being similar or identical to the MVs predicted from the surrounding MVs and, after entropy encoding, can in turn be represented by a smaller number of bits than the number of bits used when directly encoding the MVs. In some cases, MV prediction may be an example of lossless compression of a signal (i.e., MV) derived from an original signal (i.e., a sample stream). In other cases, MV prediction itself may be lossy, for example due to rounding errors that occur when calculating the predicted values from several surrounding MVs.

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

Referring to fig. 1C, the current block (111) includes samples that have been found by the encoder during the motion search process, which can be predicted from previous blocks of the same size that have generated spatial offsets. In addition, the MVs may be derived from metadata associated with one or more reference pictures, rather than directly encoding the MVs. For example, the MVs associated with any of the five surrounding samples a0, a1 and B0, B1, B2 (112 to 116, respectively) are used to derive the MVs from the metadata of the most recent reference picture (in decoding order). In h.265, MV prediction can use the prediction value of the same reference picture that the neighboring block is also using.

Video encoder and decoder

Fig. 2 is a simplified block diagram of a communication system (200) according to an embodiment disclosed herein. The communication system (200) includes a plurality of terminal devices that can communicate with each other through, for example, a network (250). For example, a communication system (200) includes a first terminal device (210) and a second terminal device (220) interconnected by a network (250). In the embodiment of fig. 2, the first terminal device (210) and the second terminal device (220) perform unidirectional data transmission. For example, a first end device (210) may encode video data, such as a stream of video pictures captured by the end device (210), for transmission over a network (250) to a second end device (220). The encoded video data is transmitted in the form of one or more encoded video streams. The second terminal device (220) may receive the encoded video data from the network (250), decode the encoded video data to recover the video data, and display a video picture according to the recovered video data. Unidirectional data transmission is common in applications such as media services.

In another embodiment, the communication system (200) includes a third terminal device (230) and a fourth terminal device (240) that perform bi-directional transmission of encoded video data, which may occur, for example, during a video conference. For bi-directional data transmission, each of the third terminal device (230) and the fourth terminal device (240) may encode video data (e.g., a stream of video pictures captured by the terminal device) for transmission over the network (250) to the other of the third terminal device (230) and the fourth terminal device (240). Each of the third terminal device (230) and the fourth terminal device (240) may also receive encoded video data transmitted by the other of the third terminal device (230) and the fourth terminal device (240), and may decode the encoded video data to recover the video data, and may display video pictures on an accessible display device according to the recovered video data.

In the embodiment of fig. 2, the first terminal device (210), the second terminal device (220), the third terminal device (230), and the fourth terminal device (240) may be a server, a personal computer, and a smart phone, but the principles disclosed herein may not be limited thereto. Embodiments disclosed herein are applicable to laptop computers, tablet computers, media players, and/or dedicated video conferencing equipment. Network (250) represents any number of networks that communicate encoded video data between first terminal device (210), second terminal device (220), third terminal device (230), and fourth terminal device (240), including, for example, wired (wired) and/or wireless communication networks. The communication network (250) may exchange data in circuit-switched and/or packet-switched channels. The network may include a telecommunications network, a local area network, a wide area network, and/or the internet. For purposes of this application, the architecture and topology of the network (250) may be immaterial to the operation disclosed herein, unless explained below.

By way of example, fig. 3 illustrates the placement of a video encoder and a video decoder in a streaming environment. The subject matter disclosed herein is equally applicable to other video-enabled applications including, for example, video conferencing, digital TV, storing compressed video on digital media including CDs, DVDs, memory sticks, and the like.

The streaming system may include an acquisition subsystem (313), which may include a video source (301), such as a digital camera, that creates an uncompressed video picture stream (302). In an embodiment, the video picture stream (302) includes samples taken by a digital camera. The video picture stream (302) is depicted as a thick line to emphasize a high data amount video picture stream compared to the encoded video data (304) (or encoded video code stream), the video picture stream (302) being processable by an electronic device (320), the electronic device (320) comprising a video encoder (303) coupled to a video source (301). The video encoder (303) may comprise hardware, software, or a combination of hardware and software to implement or embody aspects of the disclosed subject matter as described in more detail below. The encoded video data (304) (or encoded video codestream (304)) is depicted as a thin line to emphasize the lower data amount of the encoded video data (304) (or encoded video codestream (304)) as compared to the video picture stream (302), which may be stored on a streaming server (305) for future use. One or more streaming client subsystems, such as client subsystem (306) and client subsystem (308) in fig. 3, may access streaming server (305) to retrieve copies (307) and copies (309) of encoded video data (304). The client subsystem (306) may include, for example, a video decoder (310) in an electronic device (330). The video decoder (310) decodes incoming copies (307) of the encoded video data and generates an output video picture stream (311) that may be presented on a display (312), such as a display screen, or another presentation device (not depicted). In some streaming systems, encoded video data (304), video data (307), and video data (309) (e.g., video streams) may be encoded according to certain video encoding/compression standards. Examples of such standards include ITU-T H.265. In an embodiment, the Video Coding standard under development is informally referred to as next generation Video Coding (VVC), and the present application may be used in the context of the VVC standard.

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

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

The receiver (431) may receive one or more encoded video sequences to be decoded by the video decoder (410); in the same or another embodiment, the encoded video sequences are received one at a time, wherein each encoded video sequence is decoded independently of the other encoded video sequences. The encoded video sequence may be received from a channel (401), which may be a hardware/software link to a storage device that stores encoded video data. The receiver (431) may receive encoded video data as well as other data, e.g., encoded audio data and/or auxiliary data streams, which may be forwarded to their respective usage entities (not labeled). The receiver (431) may separate the encoded video sequence from other data. To prevent network jitter, a buffer memory (415) may be coupled between the receiver (431) and the entropy decoder/parser (420) (hereinafter "parser (420)"). In some applications, the buffer memory (415) is part of the video decoder (410). In other cases, the buffer memory (415) may be disposed external (not labeled) to the video decoder (410). While in other cases a buffer memory (not labeled) is provided external to the video decoder (410), e.g., to prevent network jitter, and another buffer memory (415) may be configured internal to the video decoder (410), e.g., to handle playout timing. The buffer memory (415) may not be required to be configured or may be made smaller when the receiver (431) receives data from a store/forward device with sufficient bandwidth and controllability or from an isochronous network. Of course, for use over traffic packet networks such as the internet, a buffer memory (415) may also be required, which may be relatively large and may be of an adaptive size, and may be implemented at least partially in an operating system or similar element (not labeled) external to the video decoder (410).

The video decoder (410) may include a parser (420) to reconstruct symbols (421) from the encoded video sequence. The categories of these symbols include information for managing the operation of the video decoder (410), as well as potential information to control a display device, such as a display screen (412), that is not an integral part of the electronic device (430), but may be coupled to the electronic device (430), as shown in fig. 4. The control Information for the display device may be a parameter set fragment (not shown) of Supplemental Enhancement Information (SEI message) or Video Usability Information (VUI). The parser (420) may parse/entropy decode the received encoded video sequence. Encoding of the encoded video sequence may be performed in accordance with video coding techniques or standards and may follow various principles, including variable length coding, Huffman coding, arithmetic coding with or without contextual sensitivity, and so forth. A parser (420) may extract a subgroup parameter set for at least one of the subgroups of pixels in the video decoder from the encoded video sequence based on at least one parameter corresponding to the group. A subgroup may include a Group of Pictures (GOP), a picture, a tile, a slice, a macroblock, a Coding Unit (CU), a block, a Transform Unit (TU), a Prediction Unit (PU), and so on. The parser (420) may also extract information from the encoded video sequence, such as transform coefficients, quantizer parameter values, motion vectors, and so on.

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

The reconstruction of the symbol (421) may involve a number of different units depending on the type of the encoded video picture or portion of the encoded video picture (e.g., inter and intra pictures, inter and intra blocks), among other factors. Which units are involved and the way in which they are involved can be controlled by subgroup control information parsed from the coded video sequence by a parser (420). For the sake of brevity, such a subgroup control information flow between parser (420) and a plurality of units below is not described.

In addition to the functional blocks already mentioned, the video decoder (410) may be conceptually subdivided into several functional units as described below. In a practical embodiment operating under business constraints, many of these units interact closely with each other and may be integrated with each other. However, for the purposes of describing the disclosed subject matter, a conceptual subdivision into the following functional units is appropriate.

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

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

In other cases, the output samples of sealer/inverse transform unit (451) may belong to inter-coded and potential motion compensated blocks. In this case, motion compensated prediction unit (453) may access reference picture memory (457) to extract samples for prediction. After motion compensating the extracted samples according to the sign (421), the samples may be added to the output of the scaler/inverse transform unit (451), in this case referred to as residual samples or residual signals, by an aggregator (455), thereby generating output sample information. The fetching of prediction samples by motion compensated prediction unit (453) from addresses within reference picture memory (457) may be controlled by motion vectors, and the motion vectors are used by motion compensated prediction unit (453) in the form of the symbol (421), e.g., comprising X, Y and a reference picture component. Motion compensation may also include interpolation of sample values fetched from the reference picture memory (457), motion vector prediction mechanisms, etc., when using sub-sample exact motion vectors.

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

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

Once fully reconstructed, some of the coded pictures may be used as reference pictures for future prediction. For example, once the encoded picture corresponding to the current picture is fully reconstructed and the encoded picture is identified (by, e.g., parser (420)) as a reference picture, current picture buffer (458) may become part of reference picture memory (457) and a new current picture buffer may be reallocated before reconstruction of a subsequent encoded picture begins.

The video decoder (410) may perform decoding operations according to predetermined video compression techniques, such as in the ITU-T h.265 standard. The encoded video sequence may conform to the syntax specified by the video compression technique or standard used, in the sense that the encoded video sequence conforms to the syntax of the video compression technique or standard and the configuration files recorded in the video compression technique or standard. In particular, the configuration file may select certain tools from all tools available in the video compression technology or standard as the only tools available under the configuration file. For compliance, the complexity of the encoded video sequence is also required to be within the limits defined by the level of the video compression technique or standard. In some cases, the hierarchy limits the maximum picture size, the maximum frame rate, the maximum reconstruction sampling rate (measured in units of, e.g., mega samples per second), the maximum reference picture size, and so on. In some cases, the limits set by the hierarchy may be further defined by a Hypothetical Reference Decoder (HRD) specification and metadata signaled HRD buffer management in the encoded video sequence.

In an embodiment, receiver (431) may receive additional (redundant) data along with the encoded video. The additional data may be part of an encoded video sequence. The additional data may be used by the video decoder (410) to properly decode the data and/or more accurately reconstruct the original video data. The additional data may be in the form of, for example, a temporal, spatial, or signal-to-noise ratio (SNR) enhancement layer, a redundant slice, a redundant picture, a forward error correction code, and so forth.

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

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

The video source (501) may provide a source video sequence in the form of a stream of digital video samples to be encoded by the video encoder (503), which may have any suitable bit depth (e.g., 8-bit, 10-bit, 12-bit … …), any color space (e.g., bt.601y CrCB, RGB … …), and any suitable sampling structure (e.g., Y CrCB 4:2:0, Y CrCB 4:4: 4). In the media service system, the video source (501) may be a storage device that stores previously prepared video. In a video conferencing system, the video source (501) may be a camera that captures local image information as a video sequence. Video data may be provided as a plurality of individual pictures that are given motion when viewed in sequence. The picture itself may be constructed as an array of spatial pixels, where each pixel may comprise one or more samples, depending on the sampling structure, color space, etc. used. The relationship between pixels and samples can be readily understood by those skilled in the art. The following text focuses on describing the samples.

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

In some embodiments, the video encoder (503) operates in an encoding loop. As a brief description, in an embodiment, an encoding loop may include a source encoder (530) (e.g., responsible for creating symbols, such as a symbol stream, based on input pictures and reference pictures to be encoded) and a (local) decoder (533) embedded in the video encoder (503). The decoder (533) reconstructs the symbols to create sample data in a similar manner as the (remote) decoder creates the sample data (since any compression between the symbols and the encoded video bitstream is lossless in the video compression techniques considered in this application). 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 independent of decoder location (local or remote), the content in the reference picture store (534) also corresponds bit-accurately between the local encoder and the remote encoder. In other words, the reference picture samples that the prediction portion of the encoder "sees" are identical to the sample values that the decoder would "see" when using prediction during decoding. This reference picture synchronization philosophy (and the drift that occurs if synchronization cannot be maintained due to, for example, channel errors) is also used in some related techniques.

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

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

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

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

The predictor (535) may perform a prediction search against the coding engine (532). That is, for a new picture to be encoded, predictor (535) may search reference picture memory (534) for sample data (as candidate reference pixel blocks) or some metadata, such as reference picture motion vectors, block shapes, etc., that may be referenced as appropriate predictions for the new picture. The predictor (535) may operate on a block-by-block basis of samples to find a suitable prediction reference. In some cases, from search results obtained by predictor (535), it may be determined that the input picture may have prediction references taken from multiple reference pictures stored in reference picture memory (534).

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

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

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

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

Intra pictures (I pictures), which may be pictures that can be encoded and decoded without using any other picture in the sequence as a prediction source. Some video codecs tolerate different types of intra pictures, including, for example, Independent Decoder Refresh ("IDR") pictures. Those skilled in the art are aware of variants of picture I and their corresponding applications and features.

Predictive pictures (P pictures), which may be pictures that may be encoded and decoded using intra prediction or inter prediction that uses at most one motion vector and reference index to predict sample values of each block.

Bi-predictive pictures (B-pictures), which may be pictures that can be encoded and decoded using intra-prediction or inter-prediction that uses at most two motion vectors and reference indices to predict sample values of each block. Similarly, multiple predictive pictures may use more than two reference pictures and associated metadata for reconstructing a single block.

A source picture may typically be spatially subdivided into blocks of samples (e.g., blocks of 4 x 4, 8 x 8, 4 x 8, or 16 x 16 samples) and encoded block-wise. These blocks may be predictively encoded with reference to other (encoded) blocks that are determined according to the encoding allocation applied to their respective pictures. For example, a block of an I picture may be non-predictive encoded, or the block may be predictive encoded (spatial prediction or intra prediction) with reference to an already encoded block of the same picture. The pixel block of the P picture can be prediction-coded by spatial prediction or by temporal prediction with reference to one previously coded reference picture. A block of a B picture may be prediction coded by spatial prediction or by temporal prediction with reference to one or two previously coded reference pictures.

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

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

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

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

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

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

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

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

In the embodiment of fig. 6, the video encoder (603) comprises 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 encoder (625) coupled together as shown in fig. 6.

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

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

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

A residual calculator (623) is used to calculate the difference (residual data) between the received block and the prediction result selected from the intra encoder (622) or the inter encoder (630). A residual encoder (624) is operative based on the residual data to encode the residual data to generate transform coefficients. In an embodiment, a residual encoder (624) is used to convert residual data from the time domain to the frequency domain and 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). A residual decoder (628) is used to perform the inverse transform and generate decoded residual data. The decoded residual data may be suitably used by an intra encoder (622) and an inter encoder (630). For example, inter encoder (630) may generate a decoded block based on decoded residual data and inter prediction information, and intra encoder (622) may generate a decoded block based on decoded residual data and intra prediction information. The decoded blocks are processed appropriately to generate a decoded picture, and in some embodiments, the decoded picture may be buffered in a memory circuit (not shown) and used as a reference picture.

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

Fig. 7 is a diagram of a video decoder (710) according to another embodiment of the present disclosure. A video decoder (710) is for receiving an encoded image that is part of an encoded video sequence and decoding the encoded image to generate a reconstructed picture. In an embodiment, the video decoder (710) is used in place of the video decoder (310) in the fig. 3 embodiment.

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

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

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

An intra decoder (772) is used for receiving intra prediction information and generating a prediction result based on the intra prediction information.

A residual decoder (773) is used to perform inverse quantization to extract dequantized transform coefficients and process the dequantized transform coefficients to convert the residual from the frequency domain to the spatial domain. The residual decoder (773) may also need some control information (to obtain the quantizer parameter QP) and that information may be provided by the entropy decoder (771) (data path not labeled as this is only low-level control information).

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

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

Intra prediction in VVC

Fig. 8A illustrates a schematic diagram of exemplary intra prediction directions and corresponding intra prediction modes in some examples (e.g., VVC). In FIG. 8A, there are 95 INTRA prediction modes (modes-14 ~ 80) in total, where mode 0 is a PLANAR mode (called INTRA _ PLANAR), mode 1 is a DC mode (called INTRA _ DC), and the other modes (modes-14 ~ 1 and 2 ~ 80) are ANGULAR (or directional) modes (also called INTRA _ ANGULAR). In the angle (or direction) mode, mode 18 (referred to as INTRA _ ANGULAR18) is horizontal mode, mode 50 (referred to as INTRA _ ANGULAR50) is vertical mode, mode 2 (referred to as INTRA _ ANGULAR2) refers to diagonal mode to the lower left, mode 34 (referred to as INTRA _ ANGULAR34) is diagonal mode pointing to the upper left, and mode 66 (referred to as INTRA _ ANGULAR66) is diagonal mode pointing to the upper right. The modes-14 to-1 and 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 listed in fig. 8B.

Position Dependent Prediction Combining (PDPC) filtering process

According to embodiments of the application, the Position Dependent Prediction Combining (PDPC) can be applied without signaling to the following intra modes: a planar mode, a DC mode, a WAIP mode, a horizontal mode, a vertical mode, a lower left angle mode (mode 2) and 8 adjacent angle modes thereof (mode 3 to mode 10), and an upper right angle mode (mode 66) and 8 adjacent angle modes thereof (mode 58 to mode 65).

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

pred' [ x ] [ y ] (wLxR (-1, y) + wT xR (x, -1) -wTL xR (-1, -1) + (64-wL-wT + wTL) × pred [ x ] [ y ] +32) > 6 (equation 1)

Wherein pred [ x ] [ y ] is an intra prediction value generated by the intra prediction mode; r (x, -1) represents an (unfiltered) reference sample, which is located on the top reference line of the current sample (x, y) and has the same horizontal coordinate as the current sample (x, y); r (-1, y) represents an (unfiltered) reference sample, which is located on the left reference line of the current sample (x, y) and has the same vertical coordinate as the current sample (x, y); r (-1, -1) represents a reference sample located at the upper left corner of the current block; wT, wL, and wTL represent weighting factors.

In an embodiment, when the intra prediction mode is the DC mode, the weighting factor may be calculated by equations 2 to 5.

wT 32 > ((y < 1) > nScale) (equation 2)

wL 32 > ((x < 1) > nScale) (equation 3)

wTL ═ 4 (wL > 4) + (wT > 4) (equation 4)

nScale ═ (log2(width) + log2(height) -2) > 2 (equation 5)

Where wT represents the weighting factor for the reference sample (x, -1), wL represents the weighting factor for the reference sample (-1, y), and wTL represents the weighting factor for the upper left reference sample (-1, -1), nccale (referred to as the weighting factor decrement rate) specifies the rate at which these weighting factors decrease along the axis (e.g., wL decreases from left to right along the x-axis, or wT decreases from top to bottom along the y-axis). The constant 32 in equations 2 and 3 represents the initial weighting factor for the neighboring samples (e.g., the top neighboring sample, the left neighboring sample, or the top left neighboring sample). An initial weighting factor is also assigned to the top-left sample of the current block. The weighting factors of adjacent samples in the PDPC filtering process are equal to or less than the initial weighting factor.

In an embodiment, when the intra prediction mode is the planar mode, wTL is set equal to 0; when the intra prediction mode is the horizontal mode, wTL is set equal to wT; when the intra prediction mode is the vertical mode, wTL is set equal to wL. The PDPC weighting factors may be calculated using addition operations and shift operations. The value of pred' [ x ] [ y ] can be calculated by equation 1.

Fig. 9A shows exemplary weighting factors for the prediction samples at (0, 0) in DC mode. In the example of fig. 9A, the current block is a 4x4 block (width-height-4), so ncale is 0. Then, wT is 32, wL is 32, wTL is 4.

Fig. 9B shows exemplary weighting factors for the prediction samples at (1, 0) in DC mode. In the example of fig. 9B, the current block is a 4x4 block (width-height-4), so ncale is 0. Then, wT is 32, wL is 8, wTL is 2.

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

Exemplary PDPC Filtering Process

In some examples, the inputs to the PDPC filtering process include:

intra prediction mode represented by preModeIntra;

the width of the current block, denoted by nTbW;

height of the current block, denoted by nTbH;

the width of the reference sample denoted by refW;

height of the reference sample, denoted by refH;

prediction samples represented by predSamples [ x ] [ y ], where x ═ 0.. nTbW-1, y ═ 0.. nTbH-1;

unfiltered reference (also referred to as adjacent) samples denoted by p [ x ] [ y ], where x-1, y-1.. refH-1, and x-0.. refW-1, y-1; and

the color component of the current block is represented by cIdx.

Depending on the value of cIdx, the function clip1Cmp is set as follows:

If cIdx equals 0, Clip1Cmp is set equal to Clip1 _Y 。

Otherwise, Clip1Cmp is set equal to Clip1 _C 。

Further, the output of the PDPC filtering process is the modified prediction samples predSamples' [ x ] [ y ], where x ═ 0.. nTbW-1, y ═ 0.. nTbH-1.

Then, the scaling factor nScale can be calculated by equation 6.

nScale ═ ((Log2(nTbW) + Log2(nTbH) -2) > 2) (equation 6)

Further, a reference sample array mainRef [ x ] of x-0.. refW may be defined as an array of unfiltered reference samples above the current block, and another reference sample array sideRef [ y ] of 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 unfiltered reference samples according to equations 7-8, respectively.

mainRef [ x ] ═ p [ x ] [ -1] (equation 7)

sideRef [ y ] ═ p [ -1] [ y ] (equation 8)

For each position (x, y) in the current block, the PDPC calculation may use the reference sample at the top, denoted refT [ x ] [ y ], the reference sample at the left, denoted refL [ x ] [ y ], and the reference sample at the angle p [ -1, -1 ]. The modified prediction sample can be calculated by equation 9 and the result is appropriately adjusted according to the variable cIdx indicating the color component.

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.

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.

refL [ x ] [ y ] ═ p [ -1] [ y ] (equation 10)

refT [ x ] [ y ] ═ p [ x ] [ -1] (equation 11)

wT [ y ] > ((y < 1) > nScale) (equation 12)

wL [ x ] > ((x < 1) > nScale) (equation 13)

wTL [ x ] [ y ] (predModeIntra ═ INTRA _ DC)? ((wL [ x ] > 4) + (wT [ y ] > 4)): 0 (equation 14)

Otherwise, when 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.

refL [ x ] [ y ] ═ p [ -1] [ y ] (equation 15)

refT [ x ] [ y ] ═ p [ x ] [ -1] (equation 16)

Is wT [ y ] (predModeIntra ═ INTRA _ ANGULAR 18)? 32 > ((y < 1) > nScale): 0 (equation 17)

wL [ x ] (predModeIntra ═ INTRA _ ANGULAR 50)? 32 > ((x < 1) > nScale): 0 (equation 18)

wTL [ x ] [ y ] (predModeIntra ═ INTRA _ ANGULAR 18)? wT [ y ]: wL [ x ] (equation 19)

Otherwise, when 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.

refL [ x ] [ y ] ═ p [ -1] [ x + y +1] (equation 20)

refT [ x ] [ y ] ═ p [ x + y +1] [ -1] (equation 21)

wT [ y ] (32 > 1) > ((y < 1) > nScale) (equation 22)

wL [ x ] > (32 > 1) > ((x < 1) > nScale) (equation 23)

wTL [ x ] [ y ] ═ 0 (equation 24)

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

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

dXPos [ y ] ((y +1) × invAngle +2) > 2 (equation 25)

dXFlac [ y ] ═ dXPos [ y ] &63 (Eq. 26)

dXINt [ y ] ═ dXPos [ y ] > 6 (equation 27)

dX [ x ] [ y ] ═ x + dXInt [ y ] (equation 28)

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

refL [ x ] [ y ] ═ 0 (equation 29)

refT [ x ] [ y ], (dX [ x ] [ y ] < refW-1)? MAnRef [ dX [ x ] [ y ] + (dXFrac [ y ] > 5) ]: 0 (equation 30)

wT [ y ] - (dX [ y ] < refW-1)? 32 > ((y < 1) > nScale): 0 (equation 31)

wL [ x ] ═ 0 (equation 32)

wTL [ x ] [ y ] ═ 0 (equation 33)

Otherwise, when the INTRA prediction mode preModeIntra is greater than or equal to INTRA _ ANGULAR58 (e.g., 58 or mode 58), the variables dYPos [ x ], dypass [ x ], dYInt [ x ], and dY [ x ] [ y ] may be derived based on the variable invAngle, where the variable invAngle is a function of the INTRA prediction mode preModeIntra. invAngle can be determined based on a lookup table that stores invAngle values corresponding to each intra-prediction mode, and then reference samples refT [ x ] [ y ], refL [ x ] [ y ] and weighting factors wL, wT, and wTL can be determined based on variables dYPos [ x ], dYFrac [ x ], dYInt [ x ], and dY [ x ] [ y ].

The variables dYPos [ x ], dYFrac [ x ], dYInt [ x ], and dY [ x ] [ y ] can be determined from equations 34-37.

dYPos [ x ] ((x +1) × invAngle +2) > 2 (equation 34)

dYFrac [ x ] ═ dYPos [ x ] &63 (Eq. 35)

dYInt [ x ] ═ dYPos [ x ] > 6 (EQUATION 36)

dY [ x ] [ y ] ═ x + dYInt [ x ] (equation 37)

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

Is refL [ x ] [ y ] (dY [ x ] [ y ] < refH-1)? sideRef [ dY [ x ] [ y ] + (dYFrac [ x ] > 5) ]: 0 (equation 38)

refT [ x ] [ y ] ═ 0 (equation 39)

wT [ y ] ═ 0 (equation 40)

wL [ x ] < refH-1? 32 > ((x < 1) > nScale): 0 (equation 41)

wTL [ x ] [ y ] ═ 0 (equation 42)

Otherwise, when the variable premodentra is between patterns 11-57 and is not one of patterns 18 and 50, the reference samples refT [ x ] [ y ], rPfl [ x ] [ y ] and the weighting factors wL, wT, and wTL are all set equal to 0.

Finally, the value of filtered sample filtSamples [ x ] [ y ] may be derived according to equation 43, where x ═ 0.. nTbW-1 and y ═ 0.. nTbH-1.

filtSamples [ x ] [ y ] ═ clip1Cmp ((refL [ x ] [ y ] × wL + refT [ x ] [ y ] × wT-p [ -1] [ -1] × wTL [ x ] [ y ] + (64-wL [ x ] -wT [ y ] + wTL [ x ] [ y ]) × predSamples [ x ] [ y ] +32) > 6) (equation 43)

In some examples (e.g., in VVC), for an nTbW × nTbH transform block in an nCbW × nCbH current block, if the current block is not encoded in intra sub-partition (ISP) mode (i.e., intrasubportionssplittype is equal to ISP _ NO _ SPLIT, as shown in VVC draft v 5), when performing intra prediction with PDPC, the range of top available reference samples (refW) is set to 2 × nTbW and the range of left available reference samples (refH) is set to 2 × nTbH. Otherwise, if the ISP is applied to the current block (i.e. intrasubportionssplittype is not equal to ISP _ NO _ SPLIT, as shown in VVC draft v 5), the range of top available reference samples (refW) is set to 2 × nCbW and the range of left available reference samples (refH) is set to 2 × nTbH.

Improved PDPC technology

In the "exemplary PDPC filtering process" or some related examples of the above section (e.g., in VTM 5.0), 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, different PDPC procedures may be applied to mode 2 and its neighboring modes (e.g., mode index equal to or less than 10). In another example, a different PDPC process is applied to the pattern 66 and its neighboring patterns (e.g., pattern index equal to or greater than 58). However, the prediction processes for the diagonal prediction mode and its neighbors are similar, so there is no obvious benefit to retaining different PDPC processes for these modes. Accordingly, embodiments of the present application provide improved techniques for PDPC processes.

The present techniques or methods may be used alone or in any order in combination. It should be noted that in the following section, PDPC may be used as a general term for the position-dependent boundary filtering process of a prediction sample, which uses position-dependent weights to apply linear combinations of prediction samples and neighboring reconstructed samples, and the results may be used to replace the original prediction samples. Therefore, the PDPC process is not limited to the process described in the section "exemplary PDPC filtering process" above.

In addition, in the following description, the diagonal intra prediction modes may be mode 2 and mode 66 in fig. 8A, the mode adjacent to mode 2 may have a mode index smaller than the horizontal mode (e.g., the intra mode index is smaller than 18), and the mode adjacent to mode 66 may have a mode index larger than the vertical mode (e.g., the intra mode index is larger than 50).

According to embodiments of the present application, the same PDPC process (e.g., the same range of available reference samples, the same weighting factor for each location) is applied to the diagonal intra-prediction mode and the modes neighboring the diagonal intra-prediction mode.

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 mode may be mode-1 to mode-14, mode 3 to mode 10, mode 58 to mode 65, and mode 67 to mode 80 in fig. 8A.

In one embodiment, the PDPC process may use only a subset of the available neighboring reference samples for blocks using a diagonal prediction mode, but may use all the available neighboring reference samples for blocks using a mode neighboring the diagonal prediction mode. For example, for a block predicted using diagonal intra prediction modes (e.g., mode 2 and mode 66 in VVC draft v 5), only refW-K top neighboring reference samples and refH-K left neighboring reference samples are used in the PDPC process, where refW and refH represent the total number of available top reference samples and available left reference samples, respectively (as specified in VVC draft v5 clause "general intra sample prediction" and also described in the section "exemplary PDPC filtering process" above), and K is a positive integer (e.g., 1, 2, 3, or 4).

In one embodiment, for diagonal modes (e.g., mode 2 and mode 66 in VVC draft v 5), all top and left available reference samples, except the rightmost and bottommost samples, are available for PDPC.

Exemplary modifications of PDPC Process

In some embodiments (e.g., embodiments a-E below), the PDPC process may be modified as follows.

Example A

Exemplary inputs to the PDPC filtering process include:

intra prediction mode represented by preModeIntra;

the width of the current block, denoted by nTbW;

height of the current block, denoted by nTbH;

the width of the reference sample denoted by refW;

height of the reference sample, denoted by refH;

prediction samples represented by predSamples [ x ] [ y ], where x ═ 0.. nTbW-1, y ═ 0.. nTbH-1;

unfiltered reference (also referred to as adjacent) samples denoted by p [ x ] [ y ], where x-1, y-1.. refH-1, and x-0.. refW-1, y-1; and

the color component of the current block is represented by cIdx.

Depending on the value of cIdx, the function clip1Cmp can be set as follows:

if cIdx equals 0, Clip1Cmp is set equal to Clip1 _Y 。

Otherwise, Clip1Cmp is set equal to Clip1 _C 。

Further, the output of the PDPC filtering process may be modified prediction samples predSamples' [ x ] [ y ], where x ═ 0.. nTbW-1, y ═ 0.. nTbH-1.

The scaling factor nccale can then be calculated by equation 44.

nScale ═ ((Log2(nTbW) + Log2(nTbH) -2) > 2) (equation 44)

Further, a reference sample array mainRef [ x ] of x-0.. refW may be defined as an array of unfiltered reference samples above the current block, and another reference sample array sideRef [ y ] of 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 unfiltered reference samples according to equations 45-46, respectively.

mainRef [ x ] ═ p [ x ] [ -1] (equation 45)

sideRef [ y ] ═ p [ -1] [ y ] (equation 46)

For each location (x, y) in the current block, the PDPC calculation may use the reference sample at the top, denoted refT [ x ] [ y ], the reference sample at the left, denoted refL [ x ] [ y ], and the reference sample at the corner p [ -1, -1 ]. In some examples, the modified prediction samples may be calculated by equation 47 and the results appropriately adjusted according to the variable cIdx indicative of the color component.

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.

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.

refL [ x ] [ y ] ═ p [ -1] [ y ] (equation 48)

refT [ x ] [ y ] ═ p [ x ] [ -1] (equation 49)

wT [ y ] > ((y < 1) > nScale) (equation 50)

wL [ x ] > ((x < 1) > nScale) (equation 51)

wTL [ x ] [ y ] (predModeIntra ═ INTRA _ DC)? ((wL [ x ] > 4) + (wT [ y ] > 4)): 0 (equation 52)

Otherwise, when 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.

refL [ x ] [ y ] ═ p [ -1] [ y ] (equation 53)

refT [ x ] [ y ] ═ p [ x ] [ -1] (equation 54)

wT [ y ═ predModeIntra ═ INTRA _ ANGULAR 18)? 32 > ((y < 1) > nScale): 0 (equation 55)

wL [ x ] (predModeIntra ═ INTRA _ ANGULAR 50)? 32 > ((x < 1) > nScale): 0 (equation 56)

wTL [ x ] [ y ] (predModeIntra ═ INTRA _ ANGULAR 18)? wT [ y ]: wL [ x ] (equation 57)

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

For example, the variables dXPos [ y ], dXFrac [ y ], dXINT [ y ], and dX [ x ] [ y ] may be determined according to equations 58 through 61.

dXPos [ y ] ((y +1) × invAngle +2) > 2 (equation 58)

dXFlac [ y ] ═ dXPos [ y ] &63 (equation 59)

dXINt [ y ] ═ dXPos [ y ] > 6 (equation 60)

dX [ x ] [ y ] ═ x + dXInt [ y ] (equation 61)

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.

refL [ x ] [ y ] ═ 0 (equation 62)

refT [ x ] [ y ], (dX [ x ] [ y ] < refW-1)? MAnRef [ dX [ x ] [ y ] + (dXFrac [ y ] > 5) ]: 0 (equation 63)

wT [ y ] - (dX [ y ] < refW-1)? 32 > ((y < 1) > nScale): 0 (equation 64)

wL [ x ] ═ 0 (equation 65)

wTL [ x ] [ y ] ═ 0 (equation 66)

Otherwise, when the INTRA prediction mode preModeIntra is greater than or equal to INTRA _ ANGULAR58 (e.g., 58 or mode 58), the variables dYPos [ x ], dypass [ x ], dYInt [ x ], and dY [ x ] [ y ] may be derived based on the variable invAngle, where the variable invAngle is a function of the INTRA prediction mode preModeIntra. invAngle can be determined based on a lookup table that stores invAngle values corresponding to each intra-prediction mode, and then reference samples refT [ x ] [ y ], refL [ x ] [ y ] and weighting factors wL, wT, and wTL can be determined based on variables dYPos [ x ], dYFrac [ x ], dYInt [ x ], and dY [ x ] [ y ].

For example, the variables dYPos [ x ], dYFrac [ x ], dYInt [ x ], and dY [ x ] [ y ] can be determined from equations 67 through 70.

dYPos [ x ] ((x +1) × invAngle +2) > 2 (equation 67)

dYFrac [ x ] ═ dYPos [ x ] &63 (Eq. 68)

dYInt [ x ] ═ dYPos [ x ] > 6 (equation 69)

dY [ x ] [ y ] ═ x + dYInt [ x ] (equation 70)

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.

Is refL [ x ] [ y ] (dY [ x ] [ y ] < refH-1)? sideRef [ dY [ x ] [ y ] + (dYFrac [ x ] > 5) ]: 0 (equation 71)

refT [ x ] [ y ] ═ 0 (equation 72)

wT [ y ] ═ 0 (equation 73)

wL [ x ] < refH-1? 32 > ((x < 1) > nScale): 0 (equation 74)

wTL [ x ] [ y ] ═ 0 (equation 75)

Otherwise, when the variable premodentra is between modes 11-57 and is not one of modes 18 and 50, the reference samples refT [ x ] [ y ], refL [ x ] [ y ] and the weighting factors wL, wT, and wTL are all set equal to 0.

Finally, the value of filtered sample filtSamples [ x ] [ y ] may be derived according to equation 76, where x ═ 0.. nTbW-1 and y ═ 0.. nTbH-1.

filtSamples [ x ] [ y ] ═ clip1Cmp ((refL [ x ] [ y ] × wL + refT [ x ] [ y ] × wT-p [ -1] [ -1] × wTL [ x ] [ y ] + (64-wL [ x ] -wT [ y ] + wTL [ x ] [ y ]) × predSamples [ x ] [ y ] +32) > 6) (equation 76)

The difference between embodiment a and the section "exemplary PDPC filtering process" described above is that in embodiment a, the same PDPC process is applied to the diagonal intra-prediction mode and the modes adjacent to the diagonal intra-prediction mode. In an example, the same PDPC procedure is applied to mode 2 and modes adjacent to mode 2 (e.g., mode index equal to or less than 10). In another example, the same PDPC process is applied to the pattern 66 and patterns adjacent to the pattern 66 (e.g., pattern index equal to or less than 58).

Example B

Exemplary inputs to the PDPC filtering process include:

intra prediction mode represented by preModeIntra;

the width of the current block, denoted by nTbW;

height of the current block, denoted by nTbH;

the width of the reference sample denoted by refW;

height of the reference sample, denoted by refH;

prediction samples represented by predSamples [ x ] [ y ], where x ═ 0.. nTbW-1, y ═ 0.. nTbH-1;

unfiltered reference (also referred to as adjacent) samples denoted by p [ x ] [ y ], where x-1, y-1.. refH-1, and x-0.. refW-1, y-1; and

the color component of the current block is represented by cIdx.

Depending on the value of cIdx, the function clip1Cmp is set as follows:

If cIdx equals 0, Clip1Cmp is set equal to Clip1 _Y 。

Otherwise, Clip1Cmp is set equal to Clip1 _C 。

Further, the output of the PDPC filtering process is the modified prediction samples predSamples' [ x ] [ y ], where x ═ 0.. nTbW-1, y ═ 0.. nTbH-1.

The scaling factor nccale can then be calculated by equation 77.

nScale ═ ((Log2(nTbW) + Log2(nTbH) -2) > 2) (equation 77)

Further, a reference sample array mainRef [ x ] of x-0.. refW may be defined as an array of unfiltered reference samples above the current block, and another reference sample array sideRef [ y ] of 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 unfiltered reference samples according to equations 78-79, respectively.

mainRef [ x ] ═ p [ x ] [ -1] (equation 78)

sideRef [ y ] ═ p [ -1] [ y ] (equation 79)

For each location (x, y) in the current block, the PDPC calculation may use the reference sample at the top, denoted refT [ x ] [ y ], the reference sample at the left, denoted refL [ x ] [ y ], and the reference sample at the corner p [ -1, -1 ]. In some examples, the modified prediction samples may be calculated by equation 80 and the results appropriately adjusted according to the variable cIdx indicative of the color component.

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.

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.

refL [ x ] [ y ] ═ p [ -1] [ y ] (equation 81)

refT [ x ] [ y ] ═ p [ x ] [ -1] (equation 82)

wT [ y ] > ((y < 1) > nScale) (equation 83)

wL [ x ] > ((x < 1) > nScale) (equation 84)

wTL [ x ] [ y ] (predModeIntra ═ INTRA _ DC)? ((wL [ x ] > 4) + (wT [ y ] > 4)): 0 (equation 85)

Otherwise, when 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.

refL [ x ] [ y ] ═ p [ -1] [ y ] (equation 86)

refT [ x ] [ y ] ═ p [ x ] [ -1] (equation 87)

Is wT [ y ] (predModeIntra ═ INTRA _ ANGULAR 18)? 32 > ((y < 1) > nScale): 0 (equation 88)

wL [ x ] (predModeIntra ═ INTRA _ ANGULAR 50)? 32 > ((x < 1) > nScale): 0 (equation 89)

wTL [ x ] [ y ] (predModeIntra ═ INTRA _ ANGULAR 18)? wT [ y ]: wL [ x ] (equation 90)

Otherwise, when the INTRA prediction mode preModeIntra is less than or equal to INTRA _ ANGULAR10 (e.g., 10 or mode 10), for each position (x, y), the variables dXPos [ y ], dXInt [ y ], and dX [ x [ y ] can be derived based on the variable invAngle, which is a function of the INTRA prediction mode preModeIntra. invAngle can be determined based on a lookup table that stores invAngle values corresponding to each intra-prediction mode, and then reference samples refT [ x ] [ y ], refL [ x ] [ y ], and weighting factors wL, wT, and wTL can be determined based on variables dXPos [ y ], dXINt [ y ], and dX [ x ] [ y ].

For example, the variables dXPos [ y ], dXINt [ y ], and dX [ x ] [ y ] may be determined according to equations 91 to 93.

dXPos [ y ] ((y +1) × invAngle +2) > 2 (equation 91)

dXINT [ y ] ═ (dXPos [ y ] +32) > 6 (EQUATION 92)

dX [ x ] [ y ] ═ x + dXInt [ y ] (equation 93)

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.

refL [ x ] [ y ] ═ 0 (equation 94)

wT [ y ] - (dX [ y ] < refW)? 32 > ((y < 1) > nScale): 0 (equation 96)

wL [ x ] ═ 0 (equation 97)

wTL [ x ] [ y ] ═ 0 (equation 98)

Otherwise, when the INTRA prediction mode preModeIntra is greater than or equal to INTRA _ ANGULAR58 (e.g., 58 or mode 58), variables dYPos [ x ], dYInt [ x ], and dY [ x ] [ y ] may be derived based on variable invAngle, where the variable invAngle is a function of the INTRA prediction mode preModeIntra. invAngle can be determined based on a lookup table that stores invAngle values corresponding to each intra-prediction mode, and then reference samples refT [ x ] [ y ], refL [ x ] [ y ] and weighting factors wL, wT, and wTL can be determined based on variables dYPos [ x ], dYInt [ x ], and dY [ x ] [ y ].

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

dYPos [ x ] ((x +1) × invAngle +2) > 2 (equation 99)

dYInt [ x ] ═ (dYPos [ x ] +32) > 6 (equation 100)

dY [ x ] [ y ] ═ x + dYInt [ x ] (equation 101)

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.

Is refL [ x ] [ y ] (dY [ x ] [ y ] < refH)? sideRef [ dY [ x ] [ y ] ]: 0 (equation 102)

refT [ x ] [ y ] ═ 0 (equation 103)

wT [ y ] ═ 0 (equation 104)

wL [ x ] < refH? 32 > ((x < 1) > nScale): 0 (equation 105)

wTL [ x ] [ y ] ═ 0 (equation 106)

Otherwise, when the variable premodentra is between modes 11-57 and is not one of modes 18 and 50, the reference samples refT [ x ] [ y ], refL [ x ] [ y ] and the weighting factors wL, wT, and wTL are all set equal to 0.

Finally, the value of filtered sample filtSamples [ x ] [ y ] may be derived from equation 107, where x is 0.. nTbW-1 and y is 0.. nTbH-1.

filtSamples [ x ] [ y ] ═ clip1Cmp ((refL [ x ] [ y ] × wL + refT [ x ] [ y ] × wT-p [ -1] [ -1] × wTL [ x ] [ y ] + (64-wL [ x ] -wT [ y ] + wTL [ x ] [ y ]) × predSamples [ x ] [ y ] +32) > 6) (equation 107)

The difference between embodiment A and embodiment B is that in embodiment B dXFrac [ y ] is not calculated (equation 59) when the INTRA prediction mode preModeIntra is less than or equal to INTRA _ ANGULAR10, and dXINT [ y ] may be calculated in a different manner (i.e., equation 60 versus equation 92) such that refT [ x ] [ y ] and wT [ y ] are calculated in a different manner than embodiment A (i.e., equation 63 versus equation 95, and equation 64 versus equation 96). Similarly, when the INTRA prediction mode preModeIntra is greater than or equal to INTRA _ ANGULAR58, in embodiment B, dYFrac [ x ] is not calculated (equation 68) and dYInt [ x ] may be calculated in a different manner (i.e., equation 69 to equation 100) so that refL [ x ] [ y ] and wL [ y ] are calculated in a different manner than embodiment a (i.e., equation 71 to equation 102, and equation 74 to equation 105).

Example C

Exemplary inputs to the PDPC filtering process include:

intra prediction mode represented by preModeIntra;

the width of the current block, denoted by nTbW;

height of the current block, denoted by nTbH;

the width of the reference sample denoted by refW;

height of the reference sample, denoted by refH;

prediction samples represented by predSamples [ x ] [ y ], where x ═ 0.. nTbW-1, y ═ 0.. nTbH-1;

unfiltered reference (also referred to as adjacent) samples denoted by p [ x ] [ y ], where x-1, y-1.. refH-1, and x-0.. refW-1, y-1; and

the color component of the current block is represented by cIdx.

Depending on the value of cIdx, the function clip1Cmp is set as follows:

if cIdx equals 0, Clip1Cmp is set equal to Clip1 _Y 。

Otherwise, Clip1Cmp is set equal to Clip1 _C 。

Further, the output of the PDPC filtering process is the modified prediction samples predSamples' [ x ] [ y ], where x ═ 0.. nTbW-1, y ═ 0.. nTbH-1.

The scaling factor nccale can then be calculated by equation 108.

nScale ═ ((Log2(nTbW) + Log2(nTbH) -2) > 2) (equation 108)

Further, a reference sample array mainRef [ x ] of x-0.. refW may be defined as an array of unfiltered reference samples above the current block, and another reference sample array sideRef [ y ] of 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 unfiltered reference samples according to equations 109-110, respectively.

mainRef [ x ] ═ p [ x ] [ -1] (equation 109)

sideRef [ y ] ═ p [ -1] [ y ] (equation 110)

For each location (x, y) in the current block, the PDPC calculation may use the reference sample at the top, denoted refT [ x ] [ y ], the reference sample at the left, denoted refL [ x ] [ y ], and the reference sample at the corner p [ -1, -1 ]. In some examples, the modified prediction samples may be calculated by equation 111 and the results appropriately adjusted according to the variable cIdx indicative of the color component.

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.

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.

refL [ x ] [ y ] ═ p [ -1] [ y ] (equation 112)

refT [ x ] [ y ] ═ p [ x ] [ -1] (equation 113)

wT [ y ] > ((y < 1) v > nScale) (equation 114)

wL [ x ] > ((x < 1) > nScale) (equation 115)

wTL [ x ] [ y ] (predModeIntra ═ INTRA _ DC)? ((wL [ x ] > 4) + (wT [ y ] > 4)): 0 (equation 116)

Otherwise, when 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.

refL [ x ] [ y ] ═ p [ -1] [ y ] (equation 117)

refT [ x ] [ y ] ═ p [ x ] [ -1] (equation 118)

Is wT [ y ] (predModeIntra ═ INTRA _ ANGULAR 18)? 32 > ((y < 1) > nScale): 0 (equation 119)

wL [ x ] (predModeIntra ═ INTRA _ ANGULAR 50)? 32 > ((x < 1) > nScale): 0 (equation 120)

wTL [ x ] [ y ] (predModeIntra ═ INTRA _ ANGULAR 18)? wT [ y ]: wL [ x ] (equation 121)

Otherwise, when the INTRA prediction mode preModeIntra is less than or equal to INTRA _ ANGULAR10 (e.g., 10 or mode 10), for each position (x, y), the variables dXInt [ y ] and dX [ x ] [ y ] may be derived based on the variable invAngle, which is a function of the INTRA prediction mode preModeIntra. invAngle can be determined based on a lookup table that stores invAngle values corresponding to each intra-prediction mode, and then reference samples refT [ x ] [ y ], refL [ x ] [ y ], and weighting factors wL, wT, and wTL can be determined based on variables dXINt [ y ] and dX [ x ] [ y ].

For example, the variables dXINt [ y ] and dX [ x ] [ y ] may be determined from equations 122-123.

dXINt [ y ] ((y +1) × invAngle +128) > 8 (equation 122)

dX [ x ] [ y ] ═ x + dXInt [ y ] (equation 123)

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.

refL x y 0 (equation 124)

Is wT [ y ] - (dX [ y ] < refW)? 32 > ((y < 1) > nScale): 0 (equation 126)

wL [ x ] ═ 0 (equation 127)

wTL [ x ] [ y ] ═ 0 (equation 128)

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

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

dYInt [ x ] ((x +1) × invAngle +128) > 8 (equation 129)

dY [ x ] [ y ] ═ x + dYInt [ x ] (equation 130)

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.

Is refL [ x ] [ y ] (dY [ x ] [ y ] < refH)? sideRef [ dY [ x ] [ y ] ]: 0 (equation 131)

refT [ x ] [ y ] ═ 0 (equation 132)

wT [ y ] ═ 0 (equation 133)

wL [ x ] < refH? 32 > ((x < 1) > nScale): 0 (equation 134)

wTL [ x ] [ y ] ═ 0 (equation 135)

Otherwise, when the variable premodentra is between modes 11-57 and is not one of modes 18 and 50, the reference samples refT [ x ] [ y ], refL [ x ] [ y ] and the weighting factors wL, wT, and wTL are all set equal to 0.

Finally, the value of filtered sample filtSamples [ x ] [ y ] may be derived from equation 136, where x ═ 0.. nTbW-1 and y ═ 0.. nTbH-1.

filtSamples [ x ] [ y ] ═ clip1Cmp ((refL [ x ] [ y ] × wL + refT [ x ] [ y ] × wT-p [ -1] [ -1] × wTL [ x ] [ y ] + (64-wL [ x ] -wT [ y ] + wTL [ x ] [ y ]) × predSamples [ x ] [ y ] +32) > 6) (equation 136)

The difference between embodiment B and embodiment C is that in embodiment C, when the INTRA prediction mode preModeIntra is less than or equal to INTRA _ angul 10, dXPos [ y ] is not calculated (equation 91), and dXInt [ y ] may be calculated in a different manner (i.e., equation 92 vs equation 122). Similarly, when the INTRA prediction mode preModeIntra is greater than or equal to INTRA _ ANGULAR58, dYPos [ x ] (equation 99) is not calculated in embodiment C, and dYInt [ x ] may be calculated in a different manner (i.e., equation 100 versus equation 129).

Example D

Exemplary inputs to the PDPC filtering process include:

intra prediction mode represented by preModeIntra;

the width of the current block, denoted by nTbW;

height of the current block, denoted by nTbH;

the width of the reference sample denoted by refW;

height of the reference sample, denoted by refH;

prediction samples represented by predSamples [ x ] [ y ], where x ═ 0.. nTbW-1, y ═ 0.. nTbH-1;

unfiltered reference (also called neighboring) samples denoted by p [ x ] [ y ], where x ═ 1, y ═ 1.. refH-1, and x ═ 0.. refW-1, y ═ 1; and

the color component of the current block is represented by cIdx.

Depending on the value of cIdx, the function clip1Cmp is set as follows:

if cIdx equals 0, Clip1Cmp is set equal to Clip1 _Y 。

Otherwise, Clip1Cmp is set equal to Clip1 _C 。

Further, the output of the PDPC filtering process is the modified prediction samples predSamples' [ x ] [ y ], where x ═ 0.. nTbW-1, y ═ 0.. nTbH-1.

The scaling factor nccale can then be calculated by equation 137.

nScale ═ ((Log2(nTbW) + Log2(nTbH) -2) > 2) (equation 137)

Further, a reference sample array mainRef [ x ] of x ═ 0.. refW may be defined as an array of unfiltered reference samples above the current block, and another reference sample array sideRef [ y ] of 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 unfiltered reference samples according to equations 138-139, respectively.

mainRef [ x ] ═ p [ x ] [ -1] (equation 138)

sideRef [ y ] ═ p [ -1] [ y ] (equation 139)

For each location (x, y) in the current block, the PDPC calculation may use the reference sample at the top, denoted refT [ x ] [ y ], the reference sample at the left, denoted refL [ x ] [ y ], and the reference sample at the corner p [ -1, -1 ]. The modified prediction samples may be calculated by equation 140 and the result appropriately adjusted according to the variable cIdx indicative of the color component.

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.

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.

refL [ x ] [ y ] ═ p [ -1] [ y ] (equation 141)

refT [ x ] [ y ] ═ p [ x ] [ -1] (equation 142)

wT [ y ] > ((y < 1) > nScale) (equation 143)

wL [ x ] > ((x < 1) > nScale) (equation 144)

wTL [ x ] [ y ] (predModeIntra ═ INTRA _ DC)? ((wL [ x ] > 4) + (wT [ y ] > 4)): 0 (equation 145)

Otherwise, when 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.

refL [ x ] [ y ] ═ p [ -1] [ y ] (equation 146)

refT [ x ] [ y ] ═ p [ x ] [ -1] (equation 147)

Is wT [ y ] (predModeIntra ═ INTRA _ ANGULAR 18)? 32 > ((y < 1) > nScale): 0 (equation 148)

wL [ x ] (predModeIntra ═ INTRA _ ANGULAR 50)? 32 > ((x < 1) > nScale): 0 (equation 149)

wTL [ x ] [ y ] (predModeIntra ═ INTRA _ ANGULAR 18)? wT [ y ]: wL [ x ] (equation 150)

Otherwise, when the INTRA prediction mode preModeIntra is equal to INTRA _ ANGULAR2 (e.g., 2 or mode 2), for each position (x, y), the variables dXPos [ y ], dXFrac [ y ], dXInt [ y ], and dX [ x [ y ] may be derived based on the variable invAngle, where the variable invAngle is a function of the INTRA prediction mode preModeIntra. invAngle can be determined based on a lookup table that stores invAngle values corresponding to each intra-prediction mode, and then reference samples refT [ x ] [ y ], refL [ x ] [ y ], and weighting factors wL, wT, and wTL can be determined based on variables dXPos [ y ], dXFrac [ y ], dXINt [ y ], and dX [ x ] [ y ].

The variables dXPos [ y ], dXFrac [ y ], dXINt [ y ], and dX [ x ] [ y ] may be determined from equations 151 through 154.

dXPos [ y ] ((y +1) × invAngle +2) > 2 (equation 151)

dXFlac [ y ] ═ dXPos [ y ] &63 (Eq. 152)

dXINt [ y ] ═ dXPos [ y ] > 6 (equation 153)

dX [ x ] [ y ] ═ x + dXInt [ y ] (equation 154)

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.

refL [ x ] [ y ] ═ 0 (equation 155)

refT [ x ] [ y ], (dX [ x ] [ y ] < refW-1)? MAnRef [ dX [ x ] [ y ] + (dXFrac [ y ] > 5) ]: 0 (equation 156)

wT [ y ] - (dX [ y ] < refW-1)? 32 > ((y < 1) > nScale): 0 (equation 157)

wL [ x ] ═ 0 (equation 158)

wTL [ x ] [ y ] ═ 0 (equation 159)

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

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

dXPos [ y ] ((y +1) × invAngle +2) > 2 (equation 160)

dXFlac [ y ] ═ dXPos [ y ] &63 (equation 161)

dXINt [ y ] ═ dXPos [ y ] > 6 (equation 162)

dX [ x ] [ y ] ═ x + dXInt [ y ] (equation 163)

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.

refL [ x ] [ y ] ═ 0 (equation 164)

refT [ x ] [ y ], (dX [ x ] [ y ] < refW-1)? MAnRef [ dX [ x ] [ y ] + (dXFrac [ y ] > 5) ]: 0 (equation 165)

wT [ y ] - (dX [ y ] < refW-1)? 32 > ((y < 1) > nScale): 0 (equation 166)

wL [ x ] ═ 0 (equation 167)

wTL [ x ] [ y ] ═ 0 (equation 168)

Otherwise, when 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 ] can be derived based on the variable invAngle, which is a function of the INTRA prediction mode preModeIntra. invAngle can be determined based on a lookup table that stores invAngle values corresponding to each intra-prediction mode, and then reference samples refT [ x ] [ y ], refL [ x ] [ y ] and weighting factors wL, wT, and wTL can be determined based on variables dYPos [ x ], dYFrac [ x ], dYInt [ x ], and dY [ x ] [ y ].

The variables dYPos [ x ], dYFrac [ x ], dYInt [ x ], and dY [ x ] [ y ] can be determined from equations 169 through 172.

dYPos [ x ] ((x +1) × invAngle +2) > 2 (equation 169)

dYFrac [ x ] ═ dYPos [ x ] &63 (Eq. 170)

dYInt [ x ] ═ dYPos [ x ] > 6 (equation 171)

dY [ x ] [ y ] ═ x + dYInt [ x ] (equation 172)

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.

Is refL [ x ] [ y ] (dY [ x ] [ y ] < refH-1)? sideRef [ dY [ x ] [ y ] + (dYFrac [ x ] > 5) ]: 0 (equation 173)

refT [ x ] [ y ] ═ 0 (equation 174)

wT [ y ] ═ 0 (equation 175)

wL [ x ] < refH-1? 32 > ((x < 1) > nScale): 0 (equation 176)

wTL [ x ] [ y ] ═ 0 (equation 177)

Otherwise, when the INTRA prediction mode preModeIntra is greater than or equal to INTRA _ ANGULAR58 (e.g., 58 or mode 58), the variables dYPos [ x ], dypass [ x ], dYInt [ x ], and dY [ x ] [ y ] may be derived based on the variable invAngle, where the variable invAngle is a function of the INTRA prediction mode preModeIntra. invAngle can be determined based on a lookup table that stores invAngle values corresponding to each intra-prediction mode, and then reference samples refT [ x ] [ y ], refL [ x ] [ y ] and weighting factors wL, wT, and wTL can be determined based on variables dYPos [ x ], dYFrac [ x ], dYInt [ x ], and dY [ x ] [ y ].

The variables dYPos [ x ], dYFrac [ x ], dYInt [ x ], and dY [ x ] [ y ] can be determined from equations 178-181.

dYPos [ x ] ((x +1) × inpAngle +2) > 2 (equation 178)

dYFrac [ x ] ═ dYPos [ x ] &63 (Eq. 179)

dYInt [ x ] ═ dYPos [ x ] > 6 (Eq. 180)

dY [ x ] [ y ] ═ x + dYInt [ x ] (equation 181)

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.

Is refL [ x ] [ y ] (dY [ x ] [ y ] < refH-1)? sideRef [ dY [ x ] [ y ] + (dYFrac [ x ] > 5) ]: 0 (equation 182)

refT [ x ] [ y ] ═ 0 (equation 183)

wT [ y ] ═ 0 (equation 184)

wL [ x ] < refH-1? 32 > ((x < 1) > nScale): 0 (equation 185)

wTL [ x ] [ y ] ═ 0 (equation 186)

Otherwise, when the variable premodentra is between modes 11-57 and is not one of modes 18 and 50, the reference samples refT [ x ] [ y ], refL [ x ] [ y ] and the weighting factors wL, wT, and wTL are all set equal to 0.

Finally, the value of filtered sample filtSamples [ x ] [ y ] may be derived according to equation 187, where x is 0.. nTbW-1 and y is 0.. nTbH-1.

filtSamples [ x ] [ y ] ═ clip1Cmp ((refL [ x ] [ y ] × wL + refT [ x ] [ y ] × wT-p [ -1] [ -1] × wTL [ x ] [ y ] + (64-wL [ x ] -wT [ y ] + wTL [ x ] [ y ]) × predSamples [ x ] [ y ] +32) > 6) (equation 187)

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

Example E

Exemplary inputs to the PDPC filtering process include:

intra prediction mode represented by preModeIntra;

the width of the current block, denoted by nTbW;

height of the current block, denoted by nTbH;

the width of the reference sample denoted by refW;

height of the reference sample, denoted by refH;

prediction samples represented by predSamples [ x ] [ y ], where x ═ 0.. nTbW-1, y ═ 0.. nTbH-1;

unfiltered reference (also referred to as adjacent) samples denoted by p [ x ] [ y ], where x-1, y-1.. refH-1, and x-0.. refW-1, y-1; and

the color component of the current block is represented by cIdx.

Depending on the value of cIdx, the function clip1Cmp is set as follows:

if cIdx equals 0, Clip1Cmp is set equal to Clip1 _Y 。

Otherwise, Clip1Cmp is set equal to Clip1 _C 。

Further, the output of the PDPC filtering process is the modified prediction samples predSamples' [ x ] [ y ], where x ═ 0.. nTbW-1, y ═ 0.. nTbH-1.

The scaling factor nccale can then be calculated by equation 188.

nScale ═ ((Log2(nTbW) + Log2(nTbH) -2) > 2) (equation 188)

Further, a reference sample array mainRef [ x ] of x-0.. refW may be defined as an array of unfiltered reference samples above the current block, and another reference sample array sideRef [ y ] of 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 unfiltered reference samples according to equations 189-190, respectively.

mainRef [ x ] ═ p [ x ] [ -1] (equation 189)

sideRef [ y ] ═ p [ -1] [ y ] (equation 190)

For each location (x, y) in the current block, the PDPC calculation may use the reference sample at the top, denoted refT [ x ] [ y ], the reference sample at the left, denoted refL [ x ] [ y ], and the reference sample at the corner p [ -1, -1 ]. In some examples, the modified prediction samples may be calculated by equation 191 and the result appropriately adjusted according to the variable cIdx indicative of the color component.

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.

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.

refL [ x ] [ y ] ═ p [ -1] [ y ] (equation 192)

refT [ x ] [ y ] ═ p [ x ] [ -1] (equation 193)

wT [ y ] > ((y < 1) > nScale) (equation 194)

wL [ x ] > ((x < 1) > nScale) (equation 195)

wTL [ x ] [ y ] (predModeIntra ═ INTRA _ DC)? ((wL [ x ] > 4) + (wT [ y ] > 4)): 0 (equation 196)

Otherwise, when 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.

refL [ x ] [ y ] ═ p [ -1] [ y ] (equation 197)

refT [ x ] [ y ] ═ p [ x ] [ -1] (equation 198)

wT [ y ═ predModeIntra ═ INTRA _ ANGULAR 18)? 32 > ((y < 1) > nScale): 0 (equation 199)

wL [ x ] (predModeIntra ═ INTRA _ ANGULAR 50)? 32 > ((x < 1) > nScale): 0 (equation 200)

wTL [ x ] [ y ] (predModeIntra ═ INTRA _ ANGULAR 18)? wT [ y ]: wL [ x ] (equation 201)

Otherwise, when the INTRA prediction mode preModeIntra is less than or equal to INTRA _ ANGULAR10 (e.g., 10 or mode 10), for each position (x, y), the variables dXInt [ y ] and dX [ x ] [ y ] may be derived based on the variable invAngle, which is a function of the INTRA prediction mode preModeIntra. invAngle can be determined based on a lookup table that stores invAngle values corresponding to each intra-prediction mode, and then reference samples refT [ x ] [ y ], refL [ x ] [ y ], and weighting factors wL, wT, and wTL can be determined based on variables dXINt [ y ] and dX [ x ] [ y ].

For example, the variables dXINt [ y ] and dX [ x ] [ y ] may be determined from equations 202-203.

dXINt [ y ] ((y +1) × invAngle +128) > 8 (equation 202)

dX [ x ] [ y ] ═ x + dXINt [ y ] (equation 203)

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.

refL [ x ] [ y ] ═ 0 (equation 204)

wT [ y ] > ((y < 1) > nScale) (equation 206)

wL [ x ] ═ 0 (equation 207)

wTL [ x ] [ y ] ═ 0 (equation 208)

Otherwise, when 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 the variable invAngle, which is a function of the INTRA prediction mode preModeIntra. invAngle can be determined based on a lookup table that stores inpAngle values corresponding to each intra prediction mode, and then reference samples refT [ x ] [ y ], refL [ x ] [ y ] and weighting factors wL, wT, and wTL can be determined based on variables dYInt [ x ] and dY [ x ] [ y ].

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

dYInt [ x ] ((x +1) × invAngle +128) > 8 (equation 209)

dY [ x ] [ y ] ═ x + dYInt [ x ] (equation 210)

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.

refL [ x ] [ y ] (dYInt [ y ] < refH-height-1)? sideRef [ dY [ x ] [ y ] ]: 0 (equation 211)

refT [ x ] [ y ] ═ 0 (equation 212)

wT [ y ] ═ 0 (equation 213)

wL [ x ] > ((x < 1) > nScale) (equation 214)

wTL [ x ] [ y ] ═ 0 (equation 215)

Otherwise, when the variable premodentra is between modes 11-57 and is not one of modes 18 and 50, the reference samples refT [ x ] [ y ], refL [ x ] [ y ] and the weighting factors wL, wT, and wTL are all set equal to 0.

Finally, the value of filtered sample filtSamples [ x ] [ y ] may be derived from equation 216, where x ═ 0.. nTbW-1 and y ═ 0.. nTbH-1.

filtSamples [ x ] [ y ] ═ clip1Cmp ((refL [ x ] [ y ] × wL + refT [ x ] [ y ] × wT-p [ -1] [ -1] × wTL [ x ] [ y ] + (64-wL [ x ] -wT [ y ] + wTL [ x ] [ y ]) × predSamples [ x ] [ y ] +32) > 6) (equation 216)

The difference between embodiment C and embodiment E is that in embodiment E, refT [ x ] [ y ] can be calculated in a different manner (i.e., equation 125 vs. equation 205) when the INTRA prediction mode preModeIntra is less than or equal to INTRA _ ANGULAR 10. Similarly, when the INTRA prediction mode preModeIntra is greater than or equal to INTRA _ ansearch 58, refL [ x ] [ y ] can be calculated in a different manner (i.e., equation 131 versus equation 211).

Early termination of PDPC procedures

According to an embodiment of the present application, the PDPC process may terminate early for intra prediction modes adjacent to diagonal intra prediction modes, such as mode-1 to mode-14, mode 3 to mode 10, mode 58 to mode 65, and mode 67 to mode 80 in fig. 8A, and the early termination depends on the fractional position pointed to by the intra prediction direction on the side reference samples used in the PDPC process.

In one embodiment, the allocation of reference sample values used in the PDPC process is modified as follows.

For intra prediction modes adjacent to mode 2, equation 30 is modified to equation 217.

refT [ x ] [ y ] ((dX [ x ] [ y ] + (dXFrac [ y ] > 5)) < refW-1)? MAnRef [ dX [ x ] [ y ] + (dXFrac [ y ] > 5) ]: 0 (equation 217)

For intra prediction modes adjacent to mode 66, equation 38 is modified to equation 218.

refL [ x ] [ y ] ((dY [ x ] [ y ] + (dXFrac [ y ] > 5)) < refH-1)? sideRef [ dY [ x ] [ y ] + (dYFrac [ x ] > 5) ]: 0 (equation 218)

Examination of reference samples

In some related embodiments (e.g., in VVC), for a current sample in the PDPC process, a sample-by-sample check is needed to determine whether a reference sample of the current sample is within a specified range. If the reference sample is not within the specified range, the PDPC weighting factor for the current sample is set to 0, e.g., as described in equations 31, 38, and 41. However, such sample-by-sample checking may not be desirable to perform, particularly for software optimization using Single Instruction Multiple Data (SIMD) techniques.

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

In an embodiment, for vertical-like intra prediction (i.e. the prediction direction is closer to the vertical intra prediction direction than the horizontal prediction direction), each column is checked, and the checking condition depends only on at least one of the number of available left reference samples, the prediction block height, and the horizontal coordinate value of the current sample to be filtered by the PDPC process.

In an embodiment, for horizontal-like intra prediction (i.e. the prediction direction is closer to the horizontal intra prediction direction than the vertical prediction direction), each row is checked, and the checking condition depends only on at least one of the number of available top reference samples, the prediction block width, and the vertical coordinate value of the current sample to be filtered by the PDPC process.

According to some embodiments, when the intra prediction angle of the intra prediction mode is equal to or greater than 2, for example ^k At a preset value of/32, the PDPC process is applied to intra prediction mode, where k is a non-negative integer, e.g., 3 or 4.

In an embodiment, for vertical-like intra prediction (i.e., the prediction direction is closer to the vertical intra prediction direction than the horizontal prediction direction), only the first (width/(2) of the current block ^5-k ) Or min (width, height)/(2) ^5-k ) Column is processed by the PDPC process.

In an embodiment, for horizontal-like intra prediction (i.e., the prediction direction is closer to the horizontal intra prediction direction than the vertical prediction direction), only the first (height/(2) of the current block ^5-k ) Or min (width, height)/(2) ^5-k ) Lines are processed by the PDPC process.

Fig. 10 shows a flowchart outlining an exemplary process (1000) according to an embodiment of the present application. In various embodiments, process (1000) is performed by processing circuitry, e.g., processing circuitry in terminal devices (210), (220), (230), and (240), processing circuitry that performs the functions of video encoder (303), processing circuitry that performs the functions of video decoder (310), processing circuitry that performs the functions of video decoder (410), processing circuitry that performs the functions of intra prediction module (452), processing circuitry that performs the functions of video encoder (503), processing circuitry that performs the functions of predictor (535), processing circuitry that performs the functions of intra encoder (622), processing circuitry that performs the functions of intra decoder (772), and so forth. In some embodiments, process (1000) is implemented in software instructions, such that when the software instructions are executed by the processing circuitry, the processing circuitry performs process (1000).

The process (1000) may generally begin at step (S1010). Wherein, in step (S1010), prediction information of a current block in a current picture, the current picture being part of an encoded video sequence, is decoded, the prediction information indicating an intra prediction direction of the current block, the intra prediction direction being one of (i) a diagonal intra prediction direction and (ii) an adjacent intra prediction direction adjacent to the diagonal intra prediction direction. The process (1000) then proceeds to step (S1020).

In step (S1020), it is determined to use a Position Dependent Prediction Combining (PDPC) process according to the intra prediction direction of the current block, wherein the same PDPC process is applied to the diagonal intra prediction direction and the neighboring intra prediction direction. The process (1000) then proceeds to step (S1030).

In step (S1030), the current block is reconstructed based on the PDPC process used on the current block.

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

In some embodiments, the diagonal intra prediction direction is one of a lower left intra prediction direction and an upper right intra prediction direction. In an embodiment, when the diagonal intra prediction direction is the lower-left intra prediction direction, the mode index of the neighboring intra prediction direction is lower (below) than the mode index of the horizontal intra prediction direction, i.e., the mode index value of the neighboring intra prediction direction is smaller than the mode index value of the horizontal intra prediction direction. For example, in FIG. 8A, for the mode indexes-14 ~ 16 of the lower left intra prediction direction, the mode indexes of the neighboring intra prediction directions (-14 ~ 18 dotted line mode indexes) are lower than the mode index 18 of the horizontal intra prediction direction. In an embodiment, when the diagonal intra prediction direction is a right-upper intra prediction direction, the mode index of the neighboring intra prediction direction is higher than the mode index of the vertical intra prediction direction. For example, in FIG. 8A, for the mode indexes 50 ~ 80 of the upper right intra prediction direction, the mode indexes of the neighboring intra prediction directions (the dotted line mode indexes between 50 ~ 80) are higher than the mode index 50 of the vertical intra prediction direction.

In an embodiment, when the intra prediction direction is the neighboring intra prediction direction, the process (1000) determines whether the intra prediction direction points to a fractional position; the process (1000) terminates the PDPC process prematurely when it is determined that the intra-prediction direction points to a fractional location.

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

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

An embodiment of the present application further provides a video decoding apparatus, including:

a decoding module to decode prediction information for a current block in a current picture, the current picture being part of an encoded video sequence, the prediction information indicating an intra-prediction direction for the current block, the intra-prediction direction being one of a diagonal intra-prediction direction and an adjacent intra-prediction direction adjacent to the diagonal intra-prediction direction;

a determining module for determining a combined PDPC process using position dependent prediction according to the intra prediction direction of the current block, wherein the same PDPC process is applied to the diagonal intra prediction direction and the adjacent intra prediction direction; and

a reconstruction module to reconstruct the current block based on the PDPC process used on the current block.

The embodiment of the present application further provides a computer device, which includes one or more processors and one or more memories, where at least one program instruction is stored in the one or more memories, and the at least one program instruction is loaded and executed by the one or more processors to implement the above-mentioned video decoding method.

The techniques described above may be implemented as computer software via computer readable instructions and physically stored in one or more computer readable media. The computer readable medium may be a non-volatile computer readable storage medium storing program instructions that, when executed by a computer for video encoding/decoding, cause the computer to perform the method for video decoding described in the above embodiments. For example, fig. 11 illustrates a computer system (1100) suitable for implementing certain embodiments of the disclosed subject matter.

The computer software may be encoded in any suitable machine code or computer language, and by assembly, compilation, linking, etc., mechanisms create code that includes instructions that are directly executable by one or more computer Central Processing Units (CPUs), Graphics Processing Units (GPUs), etc., or by way of transcoding, microcode, etc.

The instructions may be executed on various types of computers or components thereof, including, for example, personal computers, tablets, servers, smartphones, gaming devices, internet of things devices, and so forth.

The components illustrated in FIG. 11 for the computer system (1100) are exemplary in nature and are not intended to limit the scope of use or functionality of the computer software implementing embodiments of the present application in any way. Neither should the configuration of components be interpreted as having any dependency or requirement relating to any one or combination of components illustrated in the exemplary embodiments of the computer system (1100).

The computer system (1100) may include some human interface input devices. Such human interface input devices may respond to input from one or more human users through tactile input (e.g., keyboard input, swipe, data glove movement), audio input (e.g., sound, applause), visual input (e.g., gestures), olfactory input (not shown). The human-machine interface device may also be used to capture media that does not necessarily directly relate to human conscious input, such as audio (e.g., voice, music, ambient sounds), images (e.g., scanned images, photographic images obtained from still-image cameras), video (e.g., two-dimensional video, three-dimensional video including stereoscopic video).

The human interface input device may include one or more of the following (only one of which is depicted): keyboard (1101), mouse (1102), touch pad (1103), touch screen (1110), data glove (not shown), joystick (1105), microphone (1106), scanner (1107), camera (1108).

The computer system (1100) may also include certain human interface output devices. Such human interface output devices may stimulate the senses of one or more human users through, for example, tactile outputs, sounds, light, and olfactory/gustatory sensations. Such human interface output devices may include tactile output devices (e.g., tactile feedback through a touch screen (1110), data glove (not shown), or joystick (1105), but there may also be tactile 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 cathode ray tube screens, liquid crystal screens, plasma screens, organic light emitting diode screens, each with or without touch screen input functionality, each with or without haptic feedback functionality-some of which may output two-dimensional visual output or more than three-dimensional output by means such as stereoscopic picture output; virtual reality glasses (not shown), holographic displays and smoke boxes (not shown)), and printers (not shown). These visual output devices, such as a screen (1110), may be connected to the system bus (1148) through a graphics adapter (1150).

The computer system (1100) may also include human-accessible storage devices and their associated media, such as optical media including compact disc read-only/rewritable (CD/DVD ROM/RW) (1120) or similar media (1121) with CD/DVD, thumb drives (1122), removable hard drives or solid state drives (1123), conventional magnetic media such as magnetic tapes and floppy disks (not shown), ROM/ASIC/PLD based application specific devices such as secure dongle (not shown), and the like.

Those skilled in the art will also appreciate that the term "computer-readable medium" used in connection with the disclosed subject matter does not include transmission media, carrier waves, or other transitory signals.

The computer system (1100) may also include a network interface (1154) to one or more communication networks (1155). For example, the one or more communication networks (1155) may be wireless, wired, optical. The one or more communication networks (1155) may also be local area networks, wide area networks, metropolitan area networks, vehicular and industrial networks, real-time networks, delay tolerant networks, and the like. The one or more communication networks (1155) also include ethernet, wireless local area networks, local area networks such as cellular networks (GSM, 3G, 4G, 5G, LTE, etc.), television wired or wireless wide area digital networks (including cable, satellite, and terrestrial broadcast television), automotive and industrial networks (including CANBus), and so forth. Some networks typically require an external network interface adapter for connection to some general purpose data port or peripheral bus (1149) (e.g., a USB port of computer system (1100)); other systems are typically integrated into the core of the computer system (1100) by connecting 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) may communicate with other entities. The communication may be unidirectional, for reception only (e.g., wireless television), unidirectional for transmission only (e.g., CAN bus to certain CAN bus devices), or bidirectional, for example, to other computer systems over a local or wide area digital network. Each of the networks and network interfaces described above may use certain protocols and protocol stacks.

The human interface device, human accessible storage device, and network interface described above may be connected to the core (1140) of the computer system (1100).

The core (1140) may include one or more Central Processing Units (CPUs) (1141), Graphics Processing Units (GPUs) (1142), special purpose programmable processing units in the form of Field Programmable Gate Arrays (FPGAs) (1143), hardware accelerators (1144) for specific tasks, and so forth. These devices, as well as Read Only Memory (ROM) (1145), random access memory (1146), internal mass storage (e.g., internal non-user accessible hard drives, solid state disks, etc.) (1147), etc. may be connected via a system bus (1148). In some computer systems, the system bus (1148) may be accessed in the form of one or more physical plugs, so as to be expandable by additional central processing units, graphics processing units, and the like. The peripherals may be attached directly to the system bus (1148) of the core or connected through a peripheral bus (1149). The architecture of the peripheral bus includes peripheral controller interface PCI, universal serial bus USB, etc.

The CPU (1141), GPU (1142), FPGA (1143), and accelerator (1144) may execute certain instructions, which in combination may constitute the computer code. The computer code may be stored in ROM (1145) or RAM (1146). Transitional data may also be stored in RAM (1146), while persistent data may be stored in, for example, internal mass storage (1147). Fast storage and retrieval of any memory device may be achieved through the use of cache memory, which may be closely associated with one or more of CPU (1141), GPU (1142), mass storage (1147), ROM (1145), RAM (1146), and the like.

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

By way of example, and not limitation, a computer system having architecture (1100), and in particular core (1140), may provide functionality as a processor (including CPUs, GPUs, FPGAs, accelerators, etc.) executing software embodied in one or more tangible computer-readable media. Such computer-readable media may be media associated with the user-accessible mass storage described above, as well as specific memory having a non-volatile core (1140) such as core internal mass storage (1147) or ROM (1145). Software implementing various embodiments of the present application may be stored in such devices and executed by the core (1140). The computer-readable medium may include one or more memory devices or chips, according to particular needs. The software may cause the core (1140), and in particular the processors therein (including CPUs, GPUs, FPGAs, etc.), to perform certain processes or certain portions of certain processes described herein, including defining data structures stored in RAM (1146) and modifying such data structures according to software-defined processes. Additionally or alternatively, the computer system may provide functionality that is logically hardwired or otherwise embodied in circuitry (e.g., accelerator (1144)) that may operate in place of or in conjunction with software to perform certain processes or certain portions of certain processes described herein. Where appropriate, reference to software may include logic and vice versa. Where appropriate, reference to a computer-readable medium may include circuitry (e.g., an Integrated Circuit (IC)) storing executable software, circuitry comprising executable logic, or both. The present application includes any suitable combination of hardware and software.

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

Appendix A: acronyms

AMVP: advanced Motion Vector Prediction (Advanced Motion Vector Prediction)

ASIC: Application-Specific Integrated Circuit (Application-Specific Integrated Circuit)

ATMVP: optional/advanced temporal Motion Vector Prediction (Alternative/advanced Motion Vector Prediction)

BDOF: bidirectional Optical Flow (Bi-directional Optical Flow)

BIO: bidirectional Optical Flow (Bi-directional Optical Flow)

BMS: reference Set (Benchmark Set)

BV: block Vector (Block Vector)

CANBus: controller Area Network Bus (Controller Area Network Bus)

CB: coding Block (Coding Block)

And (3) CBF: coded Block Flag (Coded Block Flag)

CCLM: Cross-Component Linear Model/Model (Cross-Component Linear Model/Model)

CD: compact Disc (Compact Disc)

CPR: current Picture Referencing

CPUs: central Processing unit (Central Processing Units)

CRT: cathode Ray Tube (Cathode Ray Tube)

CTBs: coding Tree (Coding Tree Blocks)

CTUs: coding Tree unit (Coding Tree Units)

CU: coding Unit (Coding Unit)

DPB Decoder Picture Buffer (Decoder Picture Buffer)

DVD: digital Video Disc (Digital Video Disc)

FPGA: field Programmable Gate array (Field Programmable Gate Areas)

GOPs: picture group (Groups of Pictures)

GPUs: graphic Processing unit (Graphics Processing Units)

GSM: global System for Mobile communications

HDR: high Dynamic Range image (High Dynamic Range)

HEVC: high Efficiency Video Coding (High Efficiency Video Coding)

HRD: hypothetical Reference Decoder (Hypothetical Reference Decoder)

IBC: intra Block Copy (Intra Block Copy)

IC: integrated Circuit (Integrated Circuit)

ISP: intra-frame Sub-Partitions (Intra Sub-Partitions)

JEM: joint development Model (Joint Exploration Model)

JFET: joint Video development Team (Joint Video exhibition Team)

LAN: local Area Network (Local Area Network)

LCD: LCD Display (Liquid-Crystal Display)

LTE: long Term Evolution (Long-Term Evolution)

MPM: most Probable Mode (Most Probable Mode)

MTS: multiple Transform Selection (Multiple Transform Selection)

MV: motion Vector (Motion Vector)

An OLED: organic Light Emitting Diode (Organic Light-Emitting Diode)

PBs: prediction block (Prediction Blocks)

PCI: peripheral device Interconnect (Peripheral Component Interconnect)

PDPC: joint Prediction of Position decisions (Position Dependent Prediction Combination)

PLD: programmable Logic Device (Programmable Logic Device)

PU (polyurethane): prediction Unit (Prediction Unit)

RAM: random Access Memory (Random Access Memory)

ROM: Read-Only Memory (Read-Only Memory)

SBT Sub-block Transform (Sub-block Transform)

SCC Screen Content Coding

SDR: standard Dynamic Range (Standard Dynamic Range)

SEI: auxiliary Enhancement Information (supplement Enhancement Information)

SNR: Signal-to-Noise Ratio (Signal Noise Ratio)

SSD: solid state Drive (Solid-state Drive)

TUs: transformation unit (Transform Units)

USB: universal Serial Bus (Universal Serial Bus)

VPDU Visual Process Data Unit

VUI: video Usability Information (Video Usability Information)

VVC: general purpose Video Coding (Versatile Video Coding)

The WAIP: Wide-Angle Intra Prediction (Wide-Angle Intra Prediction)

Claims (14)

1. A method of video decoding, comprising:

decoding prediction information for a current block in a current picture, the current picture being part of an encoded video sequence, the prediction information indicating an intra-prediction direction for the current block, the intra-prediction direction being one of a diagonal intra-prediction direction and an adjacent intra-prediction direction that is adjacent to the diagonal intra-prediction direction;

determining a PDPC process using a position dependent prediction combination according to the intra prediction direction of the current block, wherein the PDPC process used when the intra prediction direction is the diagonal intra prediction direction is the same as the PDPC process used when the intra prediction direction is the neighboring intra prediction direction; and

reconstructing the current block based on the PDPC process used on the current block.

2. The method of claim 1, wherein the diagonal intra prediction direction is one of a lower left intra prediction direction and an upper right intra prediction direction.

3. The method of claim 2, wherein when the diagonal intra-prediction direction is the lower-left intra-prediction direction, a mode index of the neighboring intra-prediction direction is lower than a mode index of a horizontal intra-prediction direction.

4. The method of claim 2, wherein when the diagonal intra-prediction direction is the upper-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.

5. The method of claim 1, further comprising:

when the intra prediction direction is the neighboring intra prediction direction,

determining whether the intra prediction direction points to a fractional position; and

terminating the PDPC process prematurely upon determining that the intra-prediction direction points to the fractional location.

6. The method of claim 1, further comprising:

when the current sample in the current block is filtered by the PDPC process,

and determining whether the reference sample of the current sample is located in a preset range according to line-by-line inspection or column-by-column inspection.

7. The method of claim 6, wherein the column-wise examination is dependent on at least one of:

a total number of available reference samples located to the left of the current block;

a block height of the current block; and

a horizontal coordinate value of the current sample.

8. The method of claim 6, wherein the line-by-line examination depends on at least one of:

a total number of available reference samples located above the current block;

a block width of the current block; and

the vertical coordinate value of the current sample.

9. The method according to any one of claims 1 to 8, wherein the angle of the intra prediction direction is equal to or greater than a preset value.

10. The method of claim 9, further comprising:

when the intra prediction direction is closer to the vertical intra prediction direction than the horizontal intra prediction direction,

performing 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; and

when the intra-prediction direction is closer to the horizontal intra-prediction direction than the vertical intra-prediction direction,

performing 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.

11. The method of claim 9, wherein the PDPC process is applied to an intra prediction mode when an intra prediction angle is equal to or greater than a preset value, wherein the preset value is 2 ^k K is a non-negative integer,/32.

12. An apparatus for video decoding, comprising:

a decoding module to decode prediction information for a current block in a current picture, the current picture being part of an encoded video sequence, the prediction information indicating an intra-prediction direction for the current block, the intra-prediction direction being one of a diagonal intra-prediction direction and an adjacent intra-prediction direction adjacent to the diagonal intra-prediction direction;

a determining module for determining a PDPC process using a position dependent prediction combination according to the intra prediction direction of the current block, wherein the PDPC process used when the intra prediction direction is the diagonal intra prediction direction is the same as the PDPC process used when the intra prediction direction is the neighboring intra prediction direction; and

a reconstruction module to reconstruct the current block based on the PDPC process used on the current block.

13. A non-transitory computer-readable storage medium storing program instructions for causing a computer for video encoding/decoding to perform the method for video decoding according to any one of claims 1 to 11 when the program instructions are executed by the computer.

14. A computer device comprising one or more processors and one or more memories having stored therein at least one program instruction, the at least one program instruction being loaded and executed by the one or more processors to implement the method of video decoding of any of claims 1-11.

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