RU2780794C1 - Simplified method for signalling for the mode of affine linear weighted intra prediction - Google Patents

Abstract

FIELD: video data processing.

SUBSTANCE: invention relates to video encoding tools. The prediction information for the current block is decoded in the current image, said image being part of the encoded video sequence. Said prediction information indicates whether the current block is encoded using matrix-based intra prediction (MIP). In response to the prediction information indicating that the current block is encoded using MIP, the index of the MIP mode is determined, wherein the index of the MIP mode indicates one of a set of MIP modes, and the current block is reconstructed according to said one of the set of MIP modes. Herein, in response to the prediction information indicating the current block being encoded using MIP, a list of potential modes is formed, including at least one fixed potential mode, wherein the list of potential modes constitutes a preset subset of the set of MIP modes.

EFFECT: increased efficiency of video decoding.

17 cl, 15 dwg

Description

INCLUSION BY LINK

[0001] The present invention claims priority of U.S. Ordinary Application No. 16/822,985 "SIMPLIFIED SIGNALING METHOD FOR AFFINE LINEAR WEIGHTED INTRA PREDICTION MODE", filed March 18, 2020, which claims priority of U.S. Provisional Application No. 62/829,439 "SIMPLIFIED SIGNALING METHOD FOR AFFINE LINEAR WEIGHTED INTRA PREDICTION MODE", filed April 4th, 2019. The contents of previous applications are hereby incorporated by reference in their entirety.

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

[0002] This application describes embodiments generally related to video coding.

BACKGROUND OF THE INVENTION

[0003] The description of the prior art is provided herein for the purpose of presenting the overall context of the invention. The work of the authors of the invention, to the extent that it is described in this section, as well as aspects of the description that cannot be qualified as state of the art at the time of filing, neither expressly nor impliedly recognized as the state of the art underlying the present invention.

[0004] Encoding and decoding of the video signal may be performed using inter-picture prediction with motion compensation. Uncompressed digital video may include a sequence of images, each of which has a spatial size of, for example, 1920×1080 luma samples and their associated chrominance samples. The image sequence may have a fixed or variable image rate (informally also referred to as frame rate), such as 60 images per second, or 60 Hz. Uncompressed video has significant bitrate requirements. For example, 1080p60 4:2:0 video with 8 bits per sample (resolution of 1920x1080 luminance samples at 60Hz frame rate) requires about 1.5Gbps of bandwidth. An hour of such video requires more than 600 GB of storage.

[0005] One goal of video encoding and decoding may be to reduce redundancy in the input video signal by compressing. Compression can help to alleviate the aforementioned bandwidth or storage requirements, in some cases by two orders of magnitude or more. You can use both lossless and lossy compression, as well as a combination of both. Lossless compression refers to techniques for reconstructing an exact copy of the original signal from the compressed original signal. When lossy compression is used, the reconstructed signal may not be identical to the original signal, but the discrepancy between the original and reconstructed signals is small enough that the reconstructed signal can be used for the intended application. Lossy compression is widely used for video. The amount of distortion allowed depends on the application; for example, users of some custom streaming applications may tolerate higher distortion than users of broadcast television applications. With an achievable compression ratio, a higher allowed/allowable distortion may result in a higher compression ratio.

[0006] The video encoder and decoder may use techniques from several broad categories including, for example, motion compensation, transformation, quantization, and entropy coding.

[0007] Video codec technologies may include techniques known as intra-coding. With internal (intra-) coding, sample values are represented without reference to samples or other data from previously reconstructed reference pictures. In some video codecs, the image is spatially divided into blocks of samples. When all blocks of samples are encoded in intra-mode, the picture is called an intra-picture. Intra-pictures and their derivatives, such as pictures obtained in the decoder independent update mode, can be used to reset the decoder state, allowing them to be used as the first picture in the encoded video bitstream and video session, or as a still picture. The intra-block samples may be transformed and the transform coefficients may be quantized prior to entropy coding. Intra-prediction may be a technique for minimizing sample values in the pre-transform region. In some cases, the smaller the value of DC (constant component) after the transformation, and the smaller the AC (variable components) coefficients, the fewer bits are required for a given quantization step size to represent a block after entropy coding.

[0008] Conventional intra coding known, for example, from MPEG-2 generation coding technologies, does not use intra prediction. However, some more recent video compression techniques include techniques that attempt, for example, from ambient sample data and/or metadata obtained during encoding/decoding of spatially adjacent and preceding data blocks in decoding order. Such methods are hereinafter referred to as "internal prediction" methods. Note that, in at least some cases, intra prediction is only performed using reference data from the current image to be reconstructed, and not from reference images.

[0009] There may be many different forms of intra prediction. When more than one of these methods can be used in a given video coding technology, the method used can be encoded in intra prediction mode. In some cases, modes may have sub-modes and/or parameters that may be encoded separately or included in the mode codeword. The use of a particular codeword for a given combination of modes/submodes/parameters can affect the gain in coding efficiency through intra prediction and hence the entropy coding technology used to translate the codewords into the bitstream.

[0010] A certain mode of intra prediction was first specified in H.264, refined in H.265, and further refined in more modern coding technologies, for example, the joint exploration model (JEM, joint exploration model), universal video coding (VVC, versatile video coding) and a set of standards (BMS, benchmark set). The predictor block can be formed using the values of neighboring samples belonging to already available samples. The values of neighboring samples are copied into the predictor block according to the direction. The reference to the direction to be used may be encoded in the bitstream, or may be self-predictable.

SUMMARY OF THE INVENTION

[0011] Aspects of the invention provide methods and apparatus for encoding/decoding a video signal. In some examples, the video decoding apparatus includes a processing circuit.

[0012] According to aspects of the invention, a method for video decoding in a decoder is provided. Within the method, the processing circuit decodes the prediction data for the current block of the current picture included in the encoded video sequence. The prediction data indicates whether the current block is encoded using affine linear weighted intra prediction (ALWIP). In response to the prediction information indicating that the current block is encoded using ALWIP, the processing circuit determines the ALWIP mode index regardless of the prediction modes of neighboring blocks adjacent to the current block. The ALWIP mode index indicates one of a plurality of ALWIP modes. The processing circuit reconstructs the current block according to this one of the plurality of ALWIP modes.

[0013] In an embodiment, the ALWIP mode index is either a truncated binary codeword, a fixed length codeword, or a truncated unary codeword.

[0014] In an embodiment, in response to prediction information indicative of encoding the current block using ALWIP, the processing circuit compiles a list of possible modes including at least one fixed mode. At least one fixed mode is a predefined subset of the set of ALWIP modes.

[0015] In an embodiment, the total number of ALWIP modes is a power of 2.

[0016] According to aspects of the invention responsive to prediction data about the current block not being coded using ALWIP, the processing circuit determines whether one of the adjacent blocks is coded using ALWIP. When encoding one of the adjacent blocks using ALWIP, the processing circuit generates a list of possible modes based on (i) a predetermined intra prediction mode or (ii) the intra prediction mode of the other neighboring block of the adjacent blocks.

[0017] In an embodiment, the predetermined prediction mode is a flat intra prediction mode, a DC intra prediction mode, a horizontal intra prediction mode, or a vertical intra prediction mode.

[0018] In an embodiment, the processing circuit sets one of the neighboring blocks as unavailable in response to encoding one of the neighboring blocks using ALWIP.

[0019] In an embodiment, in response to prediction information indicating encoding the current block using ALWIP and using a derived mode for the associated chroma block associated with the current block, the processing circuit sets the intra prediction mode of the associated chroma block to a predetermined intra prediction mode.

[0020] According to aspects of the invention, another method for video decoding in a decoder is provided. Within this method, the processing circuit decodes the prediction data for the current block of the current picture that is included in the encoded video sequence. The prediction information indicates that the current block is encoded using affine linear weighted intra prediction (ALWIP). The processing scheme determines whether an adjacent block adjacent to the current block is encoded using ALWIP. If a neighboring block is not encoded using ALWIP, the processing circuit makes a list of possible modes based on (i) a predetermined ALWIP mode or (ii) another neighboring block's ALWIP mode. The processing circuit reconstructs the current block based on the list of possible modes.

[0021] In an embodiment, the processing circuit sets the adjacent block as unreachable in response to the adjacent block not being encoded using ALWIP.

[0022] In an embodiment, an adjacent block is adjacent to the top right or bottom left corner of the current block.

[0023] In an embodiment, the size of the list of possible modes is based on the coded neighbor block information included in the coded video sequence.

[0024] In an embodiment, the prediction information indicates that a chrominance block of the current block is associated with a plurality of luminance blocks, and the processing circuit determines whether one of the plurality of luma blocks is encoded in a non-ALWIP intra coding mode. In response to encoding a luma block in a non-ALWIP intra coding mode, the processing circuit determines the chrominance block prediction mode of the current block as a non-ALWIP intra luminance block prediction mode.

[0025] In an embodiment, the prediction data indicates that the chrominance block of the current block is associated with a plurality of luma blocks, and the processing circuit determines whether the luminance block is encoded from the plurality of luma blocks in a non-ALWIP intra coding mode. In response to encoding each of the plurality of luminance blocks using ALWIP, the processing circuit determines the prediction mode of the chrominance block of the current block as a predetermined intra prediction mode.

[0026] Aspects of the invention also provide one or more computer-readable media that stores instructions that, when executed by a video decoding computer, cause the computer to perform any of said video decoding method or a combination thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Additional features, nature and various advantages of the disclosed invention will be apparent from the following detailed description and the accompanying drawings, in which:

[0028] FIG. 1 is a simplified block diagram of a communication system in accordance with an embodiment;

[0029] FIG. 2 is a simplified block diagram of a communication system in accordance with an embodiment;

[0030] FIG. 3 is a simplified block diagram of an encoder according to an embodiment;

[0031] FIG. 4 is a simplified block diagram of an encoder according to an embodiment;

[0032] FIG. 5 is a block diagram of an encoder according to an embodiment;

[0033] FIG. 6 is a block diagram of a decoder according to another embodiment;

[0034] FIG. 7 illustrates intra prediction directions and intra prediction modes in a number of examples;

[0035] FIG. 8 is an illustration of intra prediction directions and intra prediction modes in a number of examples;

[0036] FIG. 9 is an illustration of intra multilinear prediction in a number of examples;

[0037] FIG. 10 illustrates exemplary positions of adjacent blocks to obtain a Most Likely Mode List (MPL) for the current block in a number of examples;

[0038] FIG. 11 is a table of examples of encoding a chrominance block by intra mode;

[0039] FIG. 12 is an illustration of affine linear weighted intra prediction (ALWIP) in a number of examples;

[0040] FIG. 13 is a flow diagram of an example process in accordance with some embodiments;

[0041] FIG. 14 is a flow diagram of another exemplary process in accordance with some embodiments; and

[0042] FIG. 15 is a diagram of a computer system in accordance with an embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

[0043] Video encoder and decoder

[0044] FIG. 1 shows a simplified block diagram of a communication system (100) according to an embodiment of the present invention. The communication system (100) includes a plurality of terminal devices that can communicate with each other, for example, via a network (150). For example, the communication system (100) includes a first pair of terminals (110) and (120) interconnected via a network (150). In the example shown in figure 1, the first pair of terminal devices (110) and (120) performs a unidirectional data transfer. For example, terminal (110) may encode video data (eg, a video stream captured by terminal (110)) for transmission to another terminal (120) via network (150). The encoded video data may be transmitted in the form of one or more encoded video bitstreams. The terminal device (120) may receive the encoded video data from the network (150), decode the encoded video data to reconstruct the video images, and display the video images according to the reconstructed video data. One-way communication may be inherent in media service applications and the like.

[0045] In another example, the communication system (100) includes a second pair of terminals (130) and (140) that carry out bi-directional transmission of encoded video data that may occur, for example, during a video conference. For bidirectional data communication, by way of example, each terminal of terminals (130) and (140) may encode video data (eg, a video stream captured by the terminal) for transmission to the other terminal of terminals (130) and (140). ) through the network (150). Each terminal of terminals (130) and (140) can also receive encoded video data transmitted by another terminal from terminals (130) and (140) and can decode the encoded video data to reconstruct video images and display video images on an available display device according to reconstructed video data.

[0046] In the example shown in FIG. 1, terminal devices (110), (120), (130), and (140) can be illustrated as servers, personal computers, and smartphones, but this does not limit the principles of the present invention. Embodiments of the present invention find application in laptop computers, tablet computers, media players and/or dedicated video conferencing equipment. Network (150) represents any number of networks that carry encoded video data between terminal devices (110), (120), (130) and (140), including, for example, wired and/or wireless communication networks. The communication network (150) allows data to be exchanged in a circuit-switched and/or packet-switched mode. Exemplary networks include telecommunications networks, local area networks, wide area networks, and/or the Internet. For the purposes of this discussion, the architecture and topology of the network (150) may not be relevant to the present invention unless specifically noted below.

[0047] FIG. 2 shows, as an example of the application of the disclosed invention, the placement of a video encoder and a video decoder in a streaming environment. The disclosed invention may be equally applicable to other video processing applications, including, for example, videoconferencing, digital television, storage of compressed video on digital media, including CD, DVD, memory card, etc., etc.

[0048] The streaming system may include a capture subsystem (213), which may include a video signal source (201), such as a digital camera, creating, for example, an uncompressed video stream (202). For example, the video stream (202) includes samples taken by a digital camera. The video stream (202), shown in bold to emphasize the large amount of data compared to the encoded video data (204) (or encoded video bitstreams), may be processed by an electronic device (220) that includes a video encoder (203) connected to video source (201). The video encoder (203) may include hardware, software, or a combination thereof for providing or implementing aspects of the disclosed invention, as described in more detail below. The encoded video data (204) (or the encoded video bitstream (204)) depicted with a thin line to emphasize the smaller amount of data compared to the video stream (202) may be stored on the streaming server (205) for future use. One or more streaming client subsystems, such as client subsystems (206) and (208) in FIG. 2 may access the streaming server (205) to retrieve copies (207) and (209) of the encoded video data (204). The client subsystem (206) may include a video decoder (210), such as in an electronic device (230). The video decoder (210) decodes the incoming copy (207) of the encoded video data and creates an outgoing video stream (211) that can be rendered on a display (212) (eg, a display screen) or other rendering device (not shown). In some streaming systems, the encoded video data (204), (207), and (209) (eg, video bitstreams) may be encoded according to one or another video coding/compression standard. Examples of these standards include ITU-T Recommendation H.265. For example, a video coding standard is being developed under the informal name "universal video coding" (VVC, Versatile Video Coding). The disclosed invention may be used in the context of VVC.

[0049] Note that the electronic devices (220) and (230) may include other components (not shown). For example, electronic device (220) may include a video decoder (not shown), and electronic device (230) may also include a video encoder (not shown).

[0050] FIG. 3 shows a block diagram of a video decoder (310) according to an embodiment of the present invention. The video decoder (310) may be part of the electronic device (330). The electronic device (330) may include a receiver (331) (eg, receiver circuits). Video decoder (310) may be used instead of video decoder (210) in the example shown in FIG. 2.

[0051] The receiver (331) may receive one or more encoded video sequences for decoding by the video decoder (310); in the same or another embodiment, one coded video sequence at a time, where the decoding of each coded video sequence is independent of other coded video sequences. The encoded video sequence may be received from a channel (301), which may be a hardware/software link to a storage device where the encoded video data is stored. The receiver (331) may receive the encoded video data with other data, such as encoded audio data and/or auxiliary data streams, which may be relayed to their respective utilizing entities (not shown). The receiver (331) may separate the encoded video sequence from other data. To combat network jitter, a buffer memory (315) may be connected between the receiver (331) and the entropy decoder/analyzer (320) (hereinafter "analyzer (320)"). In some applications, the buffer memory (315) is included in the video decoder (310). In others, it may not be part of the video decoder (310) (not shown). In other embodiments, there may be a buffer memory (not shown) outside the video decoder (310), for example, to combat network jitter, in addition to another buffer memory (315) within the video decoder (310), for example, to control the timing of the playout. When the receiver (331) receives data from a storage/relay device with sufficient bandwidth and controllability, or from an isosynchronous network, the buffer memory (315) may not be needed or may be small. For use in best attempt packet networks, such as the Internet, buffer memory (315) may be required, may be relatively large, and may have a predominantly adaptive size, and may at least partially be implemented in an operating system or similar elements (not shown) outside video decoder (310).

[0052] The video decoder (310) may include an analyzer (320) for reconstructing the symbols (321) from the encoded video sequence. The categories of these symbols include information used to control the operation of the video decoder (310), and possibly information to control a visualization device, such as a visualization device (312) (for example, a display screen), which is not an integral part of the electronic device (330), but may be connected to an electronic device (330) as shown in FIG. 3. The control information for the rendering device(s) may be Supplemental Enhancement Information (SEI) messages or Video Usability Information (VUI) parameter set fragments (not shown). The analyzer (320) may analyze/entropy decode the received encoded video sequence. Encoding of the encoded video sequence may be in accordance with a video coding technology or standard, and may follow various principles, including variable run length coding, Huffman coding, arithmetic coding with or without context sensitivity, and so on. The analyzer (320) can extract from the encoded video sequence a set of subgroup parameters for at least one of the subgroups of pixels in the video decoder based on at least one parameter corresponding to the group. Subgroups may include groups of pictures (GOP, Groups of Pictures), images, tiles, slices, macroblocks, coding units (CU, Coding Units), blocks, transformation units (TU, Transform Units), prediction units (PU, Prediction Units ) etc. The analyzer (320) can also extract information from the encoded video sequence, such as transform coefficients, quantizer parameter values, motion vectors, and so on.

[0053] The analyzer (320) may perform an entropy decoding/analysis operation of the video sequence received from the buffer memory (315) to create symbols (321).

[0054] Several different modules may be used for symbol reconstruction (321) depending on the type of encoded video image or parts thereof (eg: inter- and intra-pictures, inter- and intra-block) and other factors. Which modules are used and how can be determined by the subgroup management information extracted from the encoded video sequence by the analyzer (320). The flow of such subgroup management information between the analyzer (320) and multiple modules is not shown hereinafter for simplicity.

[0055] In addition to the previously mentioned functional blocks, the video decoder (310) can be fundamentally divided into several functional modules as described below. In a practical implementation operating under commercial constraints, many of these modules interact closely with one another and can, at least partially, be nested within one another. However, for the purposes of describing the disclosed invention, a fundamental subdivision into the following functional modules is appropriate.

[0056] The first module is the scaling/inverse transform module (351). The scaling/inverse transform module (351) receives the quantized transform coefficient as well as control information including the transform used, block size, quantization factor, quantization scaling matrices, and so on. as character(s) (321) from the analyzer (320). The scaling/inverse transform module (351) can output blocks containing sample values that can be input to the aggregator (355).

[0057] In some cases, the output samples of the scaling/inverse transform block (351) may refer to an intra-coded block; that is, a block that does not use predicted information from previously reconstructed images, but may use predicted information from previously reconstructed portions of the current image. Such predicted information may be provided by an intra-picture prediction module (352). In some cases, the intra-image prediction module (352) generates a block of the same size and shape as the block to be reconstructed using the previously reconstructed environment information retrieved from the current image buffer (358). The current picture buffer (358) buffers, for example, a partially reconstructed current picture and/or a fully reconstructed current picture. The aggregator (355) sometimes adds, for each sample, the prediction information generated by the intra prediction module (352) to the output sample information provided by the scaler/inverse transform module (351).

[0058] In other cases, the output samples of the scaler / demapper (351) may refer to an intra-coded block, possibly with motion compensation. In such a case, the motion compensation prediction module (353) may access the reference picture memory (357) to retrieve samples used in the prediction. After motion compensation has been applied to the extracted samples in accordance with the symbols (321) associated with the block, these samples can be added by the aggregator (355) to the output of the scaler/inverse transform module (351) (in this case referred to as residual samples or residual signal) to generation of output sample information. The addresses in the reference picture memory (357) from where the motion compensation prediction module (353) retrieves the predicted samples may be governed by motion vectors available to the motion compensation prediction module (353) in the form of symbols (321), which may have, for example, components X, Y and reference image components. Motion compensation may also include interpolation of sample values retrieved from reference picture memory (357) when precise sub-sample motion vectors, motion vector prediction mechanisms, etc. are used.

[0059] Various loop filtering techniques can be applied to the output samples of the aggregator (355) in the loop filter module (356). The video compression technologies may include deblocking filter technologies driven by parameters included in the encoded video sequence (also referred to as the encoded video bitstream) and made available to the loop filter module (356) as symbols (321) from the analyzer (320), but may also respond to meta-information obtained during the decoding of the previous (in the order of decoding) parts of the encoded image or encoded video sequence, as well as respond to previously reconstructed and loop-filtered sample values.

[0060] The loop filter module (356) may provide a stream of samples that may be fed to the renderer (312) as well as stored in reference picture memory (357) for use in future inter-picture prediction.

[0061] Some encoded pictures, when fully reconstructed, can be used as reference pictures for future prediction. For example, when the encoded picture corresponding to the current picture is completely reconstructed and the encoded picture is identified as a reference picture (eg, by the analyzer (320)), the current picture buffer (358) may become part of the reference picture memory (357), and a fresh current picture buffer may be re-allocated before the reconstruction of the next encoded picture starts.

[0062] The video decoder (310) may perform decoding operations according to a predetermined video compression technology, such as the ITU-T Rec. H.265. The encoded video sequence may conform to the syntax specified by the used video compression technology or standard in the sense that the encoded video sequence may adhere to both the syntax of the video compression technology or standard and the profiles documented in the video compression technology or standard. In particular, a profile may select certain tools as tools available for use only under that profile, from among all the tools available in a video compression technology or standard. It may also be necessary for consistency that the complexity of the encoded video sequence remain within the boundaries set by the video compression technology level or standard. In some cases, the levels limit the maximum image size, the maximum frame rate, the maximum sampling rate for reconstruction (measured in megasamples per second, for example), the maximum reference image size, and so on. The limits set by the levels, in some cases, may be further limited by the specifications of the hypothetical reference decoder (HRD, Hypothetical Reference Decoder) and metadata for managing the HRD buffer signaled in the encoded video sequence.

[0063] According to an embodiment, the receiver (331) may receive additional (redundant) data with encoded video. Additional data may be included as part of the encoded video sequence(s). The additional data may be used by the video decoder (310) to properly decode the data and/or more accurately reconstruct the original video data. The additional data may be, for example, enhancement layers in time, space, or signal-to-noise ratio (SNR), redundant slices, redundant images, forward error correction codes, and so on.

[0064] FIG. 4 shows a block diagram of a video encoder (403) according to an embodiment of the present invention. The video encoder (403) is included in the electronic device (420). The electronic device (420) includes a transmitter (440) (eg, a transmission circuit). Video encoder (403) may be used instead of video encoder (203) in the example shown in FIG. 2.

[0065] The video encoder (403) may receive video samples from a video signal source (401) (which is not included in the electronic device (420) in the example shown in Fig. 4), which may capture the video image(s) to be encoding with a video encoder (403). In another example, the video signal source (401) is included in the electronic device (420).

[0066] The video source (401) may provide the source video sequence to be encoded by the video encoder (403) in the form of a digital video sample stream of any suitable bit depth (eg: 8 bit, 10 bit, 12 bit, ...), any color space (eg, BT.601 Y CrCB, RGB, ...) and any suitable sampling structure (eg Y CrCb 4:2:0, Y CrCb 4:4:4). In a media service system, the video source (401) may be a storage device where previously prepared video is stored. In a videoconferencing system, the video source (401) may be a camera that captures local image information as a video sequence. The video data may be provided as a plurality of individual images that give a sense of movement when viewed in sequence. The images themselves may be organized as a spatial array of pixels, where each pixel may contain one or more samples depending on the sampling structure, color space, etc. used. It is not difficult for a person skilled in the art to understand the relationship between pixels and samples. The following description focuses on readings.

[0067] According to an embodiment, the video encoder (403) may encode and compress images of the source video sequence into the encoded video sequence (443) in real time or subject to any other time constraints imposed by the application. Setting the proper coding rate is one of the functions of the controller (450). In some embodiments, the controller (450) controls other functional modules, as described below, and is operatively connected to other functional modules. The connection is not shown for simplicity. The parameters set by the controller (450) may include parameters related to frequency adjustment (picture skip, quantizer, lambda value applied in rate-distortion optimization, ...), picture size, group of pictures scheme (GOP, group of pictures), maximum motion vector search area, etc. The controller (450) may be configured to have other suitable functions related to the video encoder (403) optimized for a given system design.

[0068] In some embodiments, video encoder (403) is configured to operate in a coding loop. As a very simplified description, by way of example, an encoding loop may include a source encoder (430) (e.g., responsible for creating symbols, e.g., a stream of symbols, based on an input image to be encoded and reference image(s) ) and a (local) decoder (433) built into the video encoder (403). The decoder (433) reconstructs the symbols to create sample data, in a similar manner as a (remote) decoder would (because any compression between the symbols and the encoded video bitstream is lossless in the video compression technologies of the disclosed invention). The reconstructed sample stream (sample data) enters the reference picture memory (434). Since the decoding of the symbol stream produces bit-accurate results independent of the position of the decoder (local or remote), the contents of the reference picture memory (434) will also be the same bit-accuracy for the local encoder and the remote encoder. In other words, the predicted portion of the encoder "sees" as reference picture samples exactly the same sample values as the decoder would "see" if using prediction during decoding. This fundamental principle of reference picture synchronism (and eventually drift if synchronism cannot be maintained, for example due to channel errors) is also used in some related fields of technology.

[0069] A "local" decoder (433) may operate in the same manner as a "remote" decoder, such as the video decoder (310) detailed above with reference to FIG. 3. However, again, referring to FIG. 3, since the symbols are available and encoding/decoding of the symbols into the encoded video sequence by the entropy encoder (445) and analyzer (320) can be lossless, the entropy decoding parts of the video decoder (310) including the buffer memory (315) and the analyzer (320) , may not be fully implemented in the local decoder (433).

[0070] In doing so, it can be concluded that any decoding technology present in a decoder, with the exception of analysis/entropy decoding, must also be present, in essentially identical functional form, in the corresponding encoder. For this reason, the disclosed invention is concentrated on the operation of the decoder. The description of encoding technologies can be abbreviated as they are the inverse of the decoded technologies described in detail. Only in some areas a more detailed description is required, which is given below.

[0071] According to some examples, in operation, source encoder (430) may perform motion-compensated predictive coding, in which an input picture is predictively encoded based on one or more previously encoded pictures from a video sequence, referred to as "reference pictures". Thus, the coding engine (432) encodes the differences between the pixel blocks of the input image and the pixel blocks of the reference image(s) that can be selected as the predicted reference(s) to the input image.

[0072] The local video decoder (433) may decode the encoded video data of pictures that can be specified as reference pictures based on the symbols generated by the source encoder (430). The operations of the encoding engine (432) may be predominantly lossy processes. When the encoded video data can be decoded in a video decoder (not shown in FIG. 4), the reconstructed video sequence can typically be a copy of the original video sequence with some errors. The local video decoder (433) duplicates the decoding processes that may be performed by the video decoder on the reference pictures and may cause the reconstructed reference pictures to be stored in the reference picture cache (434). Thus, the video encoder (403) can locally store copies of the reconstructed reference pictures having the same content as the reconstructed reference pictures to be received by the video decoder at the receiver side (in the absence of transmission errors).

[0073] The predictor (435) may perform prediction searches for the coding engine (432). Thus, for a new image to be encoded, the predictor (435) can search the reference image memory (434) for sample data (as candidates for the role of reference pixel blocks) or some metadata, for example, motion vectors of the reference image, block shapes etc., which can serve as a proper reference for predicting new images. The predictor (435) may operate on a sample-block-pixel-block basis to find the proper references for prediction. In some cases, according to the search results obtained by the predictor (435), the input image may have prediction references extracted from a plurality of reference pictures stored in the reference picture memory (434).

[0074] The controller (450) may control the encoding operations of the source encoder (430), including, for example, setting parameters and subgroup parameters used to encode video data.

[0075] The output signal of all the above functional modules can be entropy encoded in an entropy encoder (445). An entropy encoder (445) translates symbols generated by various functional units into a coded video sequence by lossless symbol compression according to techniques such as Huffman coding, variable run length coding, arithmetic coding, and so on.

[0076] The transmitter (440) may buffer the encoded video sequence(s) created by the entropy encoder (445) in preparation for transmission over a communication channel (460), which may be a hardware/software link to a storage device where the encoded video data. The transmitter (440) may combine the encoded video data from the video encoder (403) with other data to be transmitted, such as encoded audio data and/or auxiliary data streams (sources not shown).

[0077] The controller (450) may control the operation of the video encoder (403). During encoding, the controller (450) may assign to each encoded picture one or another encoded picture type, which may determine the encoding methods applicable to the corresponding picture. For example, images can often be assigned the following image types:

[0078] An intra-picture (I-picture) that can be encoded and decoded without using any other picture in the sequence as a prediction source. Some video codecs allow different types of intra-pictures, including, for example, pictures in the Independent Decoder Refresh ("IDR" format). The person skilled in the art will be aware of the varieties of I-images and their respective applications and features.

[0079] A predicted picture (P-picture) that can be encoded and decoded using intra prediction or inter prediction using at most one motion vector and a reference index to predict sample values of each block.

[0080] A bi-directionally predicted picture (B-picture) that can be encoded and decoded using intra prediction or inter prediction using no more than two motion vectors and reference indices to predict sample values of each block. Likewise, multi-predicted pictures may use more than two reference pictures and associated metadata to reconstruct a single block.

[0081] Source images typically allow for spatial division into multiple blocks of samples (eg, blocks of 4x4, 8x8, 4x8, or 16x16 samples each) and coding on a block-by-block basis. The blocks may be predictively encoded with reference to other (previously encoded) blocks determined by the coding assignment applied to the respective images of those blocks. For example, blocks of I-pictures may be encoded without prediction or predictively with reference to previously coded blocks of the same picture (spatial prediction or intra prediction). The pixel blocks of P-pictures may be predictively encoded by spatial prediction or temporal prediction with reference to one previously encoded reference picture. Blocks of B-pictures may be predictively encoded by spatial prediction or temporal prediction with reference to one or two previously encoded reference pictures.

[0082] The video encoder (403) may perform encoding operations according to a predetermined video coding technology or standard, such as ITU-T Rec. H.265. In operation, the video encoder (403) may perform various compression operations, including predictive coding operations that exploit temporal and spatial redundancies in the input video sequence. Therefore, the encoded video data may conform to the syntax given by the video coding technology or standard being used.

[0083] According to an embodiment, the transmitter (440) may transmit additional data with encoded video. The source encoder (430) may include such data as part of the encoded video sequence. The additional data may include temporal/spatial/SNR enhancement layers, other forms of redundant data such as redundant images and slices, SEI messages, VUI parameter set fragments, and so on.

[0084] The video may be captured as a plurality of source images (video images) in time sequence. Intra-image prediction (often abbreviated as intra-image prediction) uses spatial correlation within a given image, and inter-image prediction uses (temporal or otherwise) correlation between images. For example, a specific image to be encoded/decoded, which is called the current image, is divided into blocks. When a block in the current picture is similar to a reference block in a previously encoded and still buffered reference picture in a video, the block in the current picture may be encoded with a vector, which is referred to as a motion vector. The motion vector points to a reference block in the reference picture and may have a third dimension identifying the reference picture in case multiple reference pictures are used.

[0085] In some embodiments, a dual prediction technique may be used in inter-picture prediction. According to the double prediction method, two reference pictures are used, for example, a first reference picture and a second reference picture, both of which precede the current picture in the video in decoding order (but may be in the past and future, respectively, in display order). A block in the current picture may be encoded by a first motion vector that points to a first reference block in the first reference picture and a second motion vector that points to a second reference block in the second reference picture. A block may be predicted by a combination of the first and second reference blocks.

[0086] Additionally, a combining mode technique may be used in inter-picture prediction to improve coding efficiency.

[0087] According to some embodiments of the invention, predictions, such as inter-picture predictions and intra-picture predictions, are performed block by block. For example, according to the HEVC standard, an image in a video sequence is divided into coding tree units (CTUs) for compression, CTUs in an image are the same size, such as 64×64 pixels, 32×32 pixels, or 16×16 pixels. In general, the CTU includes three coding tree blocks (CTBs), namely one luma CTB and two chrominance CTBs. Each CTU may recursively divide the quadtree into one or more coding units (CUs). For example, a 64x64 pixel CTU can be divided into one 64x64 pixel CU or 4 32x32 pixel CUs or 16 16x16 pixel CUs. For example, each CU is analyzed to determine a prediction type for the CU, such as an inter prediction type or an intra prediction type. The CU is divided into one or more prediction units (PU) depending on temporal and/or spatial predictability. In general, each PU includes a Luma Prediction Unit (PB) and two Chroma PBs. According to an embodiment, an encoding (encoding/decoding) prediction operation is performed in a prediction block unit. Taking the luminance prediction block as an example, the prediction block includes a matrix of values (e.g., luminance values) for pixels, e.g., 8x8 pixels, 16x16 pixels, 8x16 pixels, 16x8 pixels, and the like.

[0088] FIG. 5 shows a diagram of a video encoder (503) according to another embodiment of the invention. The video encoder (503) is configured to receive a processing block (eg, a prediction block) of sample values in the current video image in the video sequence and to encode the processing block into an encoded image that is part of the encoded video sequence. For example, video encoder (503) is used instead of video encoder (203) in the example shown in FIG. 2.

[0089] In the HEVC example, video encoder (503) receives a matrix of sample values for a processing block, such as an 8x8 sample prediction block, or the like. The video encoder (503) determines whether the processing block is best encoded in intra mode, inter mode, or dual prediction mode using, for example, rate-distortion optimization. When the processing block is to be encoded in intra mode, the video encoder (503) may use an intra prediction technique to encode the processing block into an encoded picture; and when the processing unit is to be encoded in inter mode or dual prediction mode, the video encoder (503) may use an inter prediction or dual prediction technique, respectively, to encode the processing unit into an encoded picture. In some video coding technologies, the combining mode may be a sub-mode of inter-picture prediction where a motion vector is derived from one or more motion vector predictors without involving the encoded motion vector component outside of the predictors. In some other video coding technologies, there may be a motion vector component applicable to a given block. By way of example, the video encoder (503) includes other components, such as a mode determination module (not shown) for determining the mode of the processing units.

[0090] In the example shown in FIG. 5, the video encoder (503) includes an inter encoder (530), an intra encoder (522), a residual calculator (523), a switch (526), a residual encoder (524), a common controller (521), and an entropy encoder (525). ) connected to each other as shown in Fig. 5.

[0091] The inter-encoder (530) is configured to receive samples of the current block (e.g., processing block), compare the block with one or more reference blocks in reference pictures (e.g., blocks in previous pictures and later pictures), generate external prediction (eg, describing redundant information according to the intra coding method, motion vectors, combining mode information), and calculating inter prediction results (eg, prediction block) based on the inter prediction information using any suitable method. In some examples, reference pictures are decoded reference pictures that are decoded based on encoded video information.

[0092] The intra-encoder (522) is configured to receive samples of the current block (e.g., processing block), in some cases comparing the block with blocks previously encoded in the same picture, generating quantized coefficients after the transformation, and in some cases also information intra prediction (eg, intra prediction direction information according to one or more intra coding methods). By way of example, the intra encoder 522 also calculates intra prediction results (eg, prediction block) based on intra prediction information and reference blocks in the same picture.

[0093] The common controller (521) is configured to determine common control data and control other components of the video encoder (503) based on the common control data. For example, the common controller (521) determines the mode of the block and outputs a control signal to the switch (526) based on the mode. For example, when the mode is the intra mode, the common controller (521) controls the switch (526) to select the result of the intra mode for use by the residual calculator (523), and controls the entropy encoder (525) to select the intra prediction information and turn on the intra prediction information into the bitstream; and when the mode is inter mode, the common controller (521) controls the switch (526) to select the inter prediction result to be used by the residual calculator (523), and controls the entropy encoder (525) to select the inter prediction information and include the inter prediction information in the bit flow.

[0094] The residual calculator (523) is configured to calculate the difference (residual data) between the received block and the prediction results selected from the intra-coder (522) or inter-coder (530). The residual encoder (524) is configured to operate on the residual data to encode the residual data to generate transform coefficients. For example, the residual encoder (524) is configured to transform residual data from the spatial domain to the frequency domain and generate transform coefficients. Then, the transform coefficients are subjected to quantization processing to obtain quantized transform coefficients. In various embodiments, the video encoder (503) also includes a residual decoder (528). The residual decoder (528) is configured to perform inverse transformation and generate decoded residual data. The decoded residual data may be appropriately used by the intra-coder (522) and the inter-coder (530). For example, the intercoder (530) may generate decoded blocks based on the decoded residual data and inter prediction information, and the intra encoder (522) may generate decoded blocks based on the decoded residual data and intra prediction information. The decoded blocks are properly processed to generate decoded pictures, and the decoded pictures can be buffered in a memory circuit (not shown) and used as reference pictures in some examples.

[0095] The entropy encoder (525) is configured to format the bitstream so that it includes a coded block. The entropy encoder (525) is configured to include various information according to an appropriate standard, such as the HEVC standard. For example, the entropy encoder (525) is configured to include common control data, selected prediction information (eg, intra prediction information or inter prediction information), residual information, and other suitable information in the bitstream. Note that, according to the disclosed invention, when encoding a block in the combining submode of the inter mode or dual prediction mode, there is no residual information.

[0096] FIG. 6 shows a diagram of a video decoder (610) according to another embodiment of the invention. The video decoder (610) is configured to receive encoded pictures that are part of the encoded video sequence and decode the encoded pictures to generate reconstructed pictures. For example, video decoder (610) is used instead of video decoder (210) in the example shown in FIG. 2.

[0097] In the example shown in FIG. 6, the video decoder (610) includes an entropy decoder (671), an inter decoder (680), a residual decoder (673), a reconstruction unit (674), and an intra decoder (672) connected to each other as shown in FIG. 6.

[0098] The entropy decoder (671) may be configured to reconstruct from the encoded image some symbols that represent the syntax elements that make up the encoded image. Such symbols may include, for example, a block coding mode (e.g., intra mode, inter mode, dual prediction mode, the latter two being in a pooling submode or other submode), prediction information (e.g., intra prediction information, or inter prediction information ) that can identify a specific sample or metadata used for prediction by the intra-decoder (672) or inter-decoder (680), respectively, residual information in the form of, for example, quantized transform coefficients, and the like. For example, when the prediction mode is an intra or dual prediction mode, the inter prediction information is input to the inter decoder (680); and when the prediction type is an intra prediction type, the intra prediction information is input to the intra decoder (672). The residual information may be inverse quantized and fed to a residual decoder (673).

[0099] The inter decoder (680) is configured to receive inter prediction information and generate inter prediction results based on the inter prediction information.

[0100] The intra decoder (672) is configured to receive intra prediction information and generate prediction results based on the intra prediction information.

[0101] The residual decoder (673) is configured to perform inverse quantization to extract the dequantized transform coefficients and process the dequantized transform coefficients to transform the residual from the frequency domain to the spatial domain. The residual decoder (673) may also require some control information (include a quantizer parameter (QP, Quantizer Parameter)), and this information may be provided by the entropy decoder (671) (the data path is not shown since this may only be small volume control information).

[0102] The reconstruction module (674) is configured to combine in the spatial domain the residual at the output of the residual decoder (673) and the prediction results (at the output of the inter or intra prediction modules, as appropriate) to form a reconstructed block that may be included in reconstructed image, which, in turn, can be part of the reconstructed video. Note that other suitable operations, such as a release operation and the like, may be performed to improve the visual quality.

[0103] Note that video encoders (203), (403) and (503) and video decoders (210), (310) and (610) may be implemented using any suitable technique. According to an embodiment, video encoders (203), (403) and (503) and video decoders (210), (310) and (610) may be implemented using one or more integrated circuits. In another embodiment, video encoders (203), (403) and (503) and video decoders (210), (310) and (610) may be implemented using one or more processors that execute program instructions.

[0104] Intra prediction in HEVC and VVC

[0105] In the following description, the term "block" may mean a prediction block, a coding block, or a coding unit.

[0106] FIG. 7 exemplarily shows intra prediction directions and corresponding intra prediction modes in a number of examples (eg, in HEVC). Fig. 7 includes 35 intra prediction modes (modes 0-34). Mode 0 and mode 1 are non-directional modes, among which mode 0 is a flat mode (intra-prediction flat mode) and mode 1 is a DC (intra-prediction DC) mode. Modes 2-34 are directional (or angular) modes (angular intra prediction modes), among which mode 10 is horizontal mode, mode 26 is vertical mode, and mode 2, 18 and 34 are diagonal.

[0107] In some examples, for intra mode coding, a list of candidate modes is compiled from a subset of intra prediction modes. For example, one or more most probable modes form a list of potential modes, which is called the list of the most probable modes (MPM, most probable mode). In an example (eg, HEVC), the MPM list includes the three most likely modes and is compiled based on the intra prediction mode(s) of the adjacent block(s) of the current block. The MPM list is also called the primary MPM list. In such an example, an MPM flag is signaled to indicate whether the intra prediction mode of the current block is in the MPM list. If the MPM flag indicates that the intra prediction mode of the current block is taken from the MPM list, then the MPM list index is signaled to indicate one of the three most likely modes in the MPM list for the current block. However, if the MPM flag indicates that the intra prediction mode of the current block is not in the MPM list, then the mode index is signaled to indicate one of the 32 intra modes for the current block.

[0108] In some examples, the MPM listing process is as follows.

If (leftIntraDir == aboveIntraDir && leftIntraDir>DC_IDX)

MPM[0] = leftIntraDir;

MPM[1] = ((leftIntraDir+offset) % mod)+2;

MPM[2] = ((leftIntraDir - 1) % mod)+2;

Also if (leftIntraDir == aboveIntraDir)

MPM[0] = PLANAR_IDX;

MPM[1] = DC_IDX;

MPM[2] = VER_IDX;

Also if (leftIntraDir ! = above IntraDir)

MPM[0] = leftIntraDir;

MPM[1] = aboveIntraDir;

If (leftIntraDir >0 && aboveIntraDir >0)

MPM[2] = PLANAR_IDX;

Also

MPM[2] = (leftIntraDir + aboveIntraDir) < 2 ? VER_IDX: DC_IDX;

[0109] In the MPM listing process, the variable leftIntraDir indicates the intra prediction mode of the adjacent block to the left of the current block (left neighbor block), and the variable aboveIntraDir indicates the intra prediction mode of the neighboring block above the current block (upper neighbor block). If the left or top adjacent block is not available, then leftIntraDir or aboveIntraDir can be set to DC_IDX. PLANAR_IDX, DC_IDX, and VER_IDX denote the indices of flat mode (eg, mode 0), DC mode (eg, mode 1), and vertical mode (eg, mode 26), respectively. Also, the variables "offset" and "mod" have constant values, which are set to 29 and 32 respectively in the example. In such an example, when the left and top neighboring blocks have the same directional mode, the first most likely mode is set to the same directional mode. The second and third most likely modes are selected as the two directional modes closest to the mode number of the first most likely mode. When the left and top adjacent blocks have the same non-directional mode, the first, second, and third most likely modes are set to flat mode, DC mode, and vertical mode, respectively. When the left and top neighbor blocks have different intra prediction modes, the first and second most likely modes are set to the left and top neighbor block intra prediction modes, respectively, and the third most likely mode is set to one of flat mode, DC mode, and vertical mode, according to which of these modes, in that order, is not a copy of one of the first two most likely modes.

[0110] FIG. 8 illustratively shows intra prediction directions and corresponding intra prediction modes in a number of examples (eg, VVC). Fig. 8 includes 95 intra prediction modes (modes 14 to 80), among which mode 18 is a horizontal mode, mode 50 is a vertical mode, and mode 2, 34, and 66 are diagonal modes. Modes -1~-14 as well as modes 67~80 are called wide-angle intra prediction (WAIP) modes.

[0111] Similar to the example of FIG. 7, in the example of FIG. 8, an MPM list for mode coding is generated. For example, in intra multilinear prediction, the size of the MPM list is set to 6 for an adjacent reference line and 5 for non-adjacent reference lines of the current block. The adjacent reference line and non-adjacent reference lines will be described with reference to FIG. 9.

[0112] FIG. 9 illustratively demonstrates intra multilinear prediction in a number of examples (eg, VVC). In intra multilinear prediction, a plurality of reference lines are used for intra prediction. In the example of FIG. 9 shows four reference lines, that is, reference lines 0-3, where reference line 0 is an adjacent reference line, which is also called a null reference line, and reference lines 1-3 are non-adjacent reference lines, also called non-zero reference lines. Each reference line includes vertical and horizontal parts and consists of 6 segments A-F. Segments A and F are filled with the closest readings from segments B and E, respectively. Also, an upper left reference is included between segments C and D in the example of FIG. 9. The reference line index is signaled before the intra prediction modes to indicate one of the plurality of reference lines to be used. In case of non-zero reference line index signaling, only the most probable modes for intra prediction are allowed to be used.

[0113] FIG. 10 shows exemplary neighbor block positions used to obtain an MPM list for the current block in a number of examples (eg, VVC). Block A and block B denote the left and upper adjacent coding unit (CU) of the current CU, respectively. Block A is adjacent to the current CU in the lower left corner, and block B is adjacent to the current CU in the upper right corner. The variables "candIntraPredModeA" and "candIntraPredModeB" indicate the intra prediction modes of blocks A and B, respectively, and are initially set to Intra Planar. If block A (or B) is marked as available, then the variable candIntraPredModeA (or candIntraPredModeB) is set to the active intra prediction mode of block A (or B). In some examples, the positions of adjacent blocks used to derive potential MPMs are identical for adjacent and non-adjacent reference lines in intra multilinear prediction.

[0114] FIG. 11 shows a table with examples of encoding a chrominance block in an internal mode (eg, VVC). In FIG. 11 shows 8 internal chroma block coding modes: flat mode, vertical mode, horizontal mode, DC mode, derivative mode, and three cross-component linear model modes (CCLM, LM_A, and LM_L). According to the table, the coding of a chrominance block in intra mode may depend (eg, directly depends) on the intra prediction mode of the corresponding luma block. Because the chrominance and luma components may use different block division structures, for example in slice I, one chroma block may correspond to many luma blocks. Thus, when using a derived mode to encode a chrominance block in intra mode, the intra prediction mode of the corresponding luma block covering the center position of the chroma block becomes directly the intra prediction mode of the chrominance block.

[0115] FIG. 12 illustratively demonstrates affine linear weighted intra prediction (ALWIP) in a number of examples (eg, VVC). For predictor block (PB) prediction samples of width W and height H, one left column of reconstructed neighbor boundary prediction block samples H and one upper row of reconstructed neighbor boundary prediction block samples W are taken as input to ALWIP. If reconstructed adjacent boundary samples are not available, then they can be generated using other intra prediction methods. ALWIP is also called matrix based intra prediction (MIP).

[0116] In the example, the prediction block can be predicted based on the following three steps.

[0117] (1) The first set of averaged samples is obtained by averaging (e.g., subsets) of the left column of adjacent edge samples of the prediction block, and the second set of averaged samples is obtained by averaging (e.g., subsets) of the top row of neighboring edge samples of the prediction block. If W=H=4 samples, then the total number of elements of the first and second sets of averaged samples is four. In other cases, 8 average readings are obtained.

[0118] (2) The averaged samples are multiplied by a matrix vector. An offset is added to the result of the multiplication to generate a reduced prediction block on the downsampled set of samples in the original prediction block.

[0119] (3) The prediction samples at the remaining positions are generated from the reduced downsampled prediction block by applying linear interpolation to the reduced downsampled prediction block in each direction.

, i∈{0, …, 17}. В каждой матрице может быть 16 рядов и 4 столбца, а также 18 векторов смещения

, i∈{0, …, 17}. Размер каждого вектора смещения может составлять 16. Матрицы и векторы смещения, включенные в матричный набор S₀, могут применяться для блоков размером 4×4. Матричный набор S₁ состоит из или включает 10 матриц

, i∈{0, …, 9). В каждой матрице может быть 16 рядов и 8 столбцов, а также 10 векторов смещения

, i∈{0, …, 9). Размер каждого вектора смещения может составлять 16. Матрицы и векторы смещения, включенные в матричный набор S₁, могут применяться для блоков размером 4×8, 8×4 и 8×8. Матричный набор S₂ состоит из или включает 6 матриц

, i∈{0, …, 5]. Каждая матрица может иметь 64 ряда и 8 столбцов, а также 6 векторов смещения

, i∈{0, …, 5). Размер каждого вектора смещения может составлять 64. Матрицы и вектора смещения, включенные в матричный набор S₂, можно применять для блоков всех других форм и размеров.[0120] The bias matrices and vectors used to generate the reduced prediction block can be taken from three sets of matrices (S ₀ , S ₁ , and S ₂ ). The matrix set S ₀ consists of or includes 18 matrices

, i∈{0, …, 17}. Each matrix can have 16 rows and 4 columns, as well as 18 offset vectors

, i∈{0, …, 17}. The size of each displacement vector may be 16. The displacement matrices and vectors included in the matrix set S ₀ may be applied to 4x4 blocks. The matrix set S ₁ consists of or includes 10 matrices

, i∈{0, …, 9). Each matrix can have 16 rows and 8 columns, as well as 10 offset vectors

, i∈{0, …, 9). The size of each displacement vector may be 16. The displacement matrices and vectors included in the matrix set S ₁ may be applied to 4x8, 8x4, and 8x8 blocks. The matrix set S ₂ consists of or includes 6 matrices

, i∈{0, …, 5]. Each matrix can have 64 rows and 8 columns as well as 6 offset vectors

, i∈{0, …, 5). The size of each displacement vector can be 64. The displacement matrices and vectors included in the S ₂ matrix set can be applied to all other block shapes and sizes.

[0121] With an 8x8 block as in FIG. 12, ALWIP takes four vertical boundary averages and four horizontal boundary averages. The 8 final averages are the input of the matrix vector multiplication. The matrices are taken from the matrix set S1 due to the block size. Multiplication by a matrix vector yields 16 samples at odd block positions. Thus, (8×16)/(8×8)=2 multiplications per sample is performed. After adding the offset, these samples are interpolated vertically using the reduced upper limit samples, and then interpolated horizontally using the original left border samples. In this case, the interpolation process does not require any multiplications.

[0122] Obtaining the MPM List for ALWIP Intra Prediction Modes

[0123] According to aspects of the invention, a mode other than the ALWIP mode may be mapped to the ALWIP mode according to a mapping table. In one embodiment, there are three mapping tables map_angular_to_alwip _idx , idx∈[0, 1, 2], and each mapping table corresponds to a corresponding set of matrices from (S ₀ -S ₂ ) and associates an intra prediction mode different from the ALWIP predmode _Angular . with a specific ALWIP mode according to Ur. one.

[0124] The mapping table index idx indicates one of the three matrix sets from which the ALWIP parameters are taken. The index can be set based on the width W and the height H of the prediction unit (PU) and set according to Eq. 2 and 3.

[0125] According to aspects of the invention, for each intra mode coding unit, a flag is sent to the bitstream that indicates whether ALWIP is applied in the corresponding prediction unit. When the flag indicates a need to apply ALWIP, the ALWIP mode predmode index is signaled to indicate a potential mode in the Most Likely Mode List (MPM). In the example, the MPM list includes 3 potential MPMs.

и левый режим ALWIP

можно получить следующим образом.[0126] To generate an MPM list for the current ALWIP encoded block, the upper ALWIP mode

and left mode ALWIP

can be obtained as follows.

и idx(PU)=idx(PU_above), верхний режим ALWIP можно определить, согласно Ур. 4.[0127] When the upper prediction unit PU _above the current prediction unit is available and belongs to the same coding tree unit where the current prediction unit is located, and the PU _above is encoded using the ALWIP mode

and idx(PU)=idx(PU _above ), the upper ALWIP mode can be determined according to Eq. four.

, верхний режим ALWIP можно определить с помощью таблицы отображения, согласно Ур. 5.[0128] When the upper prediction unit PU _above is available and belongs to the same coding tree unit where the current prediction unit is located, and PU _above is encoded with a non-ALWIP intra prediction mode,

, the upper ALWIP mode can be determined using the mapping table according to Eq. 5.

[0129] In other cases, the upper ALWIP mode can be set as unavailable, according to Eq. 6.

можно получить тем же способом, что и режим

, но без проверки, принадлежит ли левая единица предсказания той же единице дерева кодирования, где расположена текущая единица предсказания.[0130] Value

can be obtained in the same way as the mode

, but without checking if the left prediction unit belongs to the same coding tree unit as the current prediction unit.

и

и трех заранее заданных по умолчанию фиксированных списков МРМ list_idx, idx∈{0, 1, 2}. Каждый заранее заданный по умолчанию фиксированный список МРМ состоит или включает три различных режима ALWIP. В примере недоступный режим -1 заменяется значением по умолчанию, и дублирующие режимы ALWIP удаляются.[0131] Thus, the MPM list is constructed based on the derived modes

and

and three predefined default fixed MPM lists list _idx , idx∈{0, 1, 2}. Each pre-default fixed MPM list consists of or includes three different ALWIP modes. In the example, the unavailable mode -1 is replaced with the default value and duplicate ALWIP modes are removed.

[0132] Obtaining a list of MPMs for non-ALWIP intra prediction modes

[0133] According to aspects of the invention, the ALWIP mode can be mapped to a non-ALWIP mode according to a mapping table. The mapping table can be changed based on the block size. There are three mapping tables map_alwip_to_angular _idx , idx∈{0, 1, 2}. Each mapping table corresponds to a corresponding set of matrices (S ₀ -S ₂ ) and associates an ALWIP predmode _{ALWIP intra} prediction mode with a specific non-ALWIP intra prediction mode as shown in Eq. 7.

[0134] To obtain an MPM list for a luma block when an adjacent luminance block block is encoded in ALWIP mode, one of three mapping tables can be used to map the ALWIP mode to the corresponding non-ALWIP intra prediction mode. To obtain the MPM list of a chrominance block when the associated luma block is encoded in ALWIP mode, the same mapping is applied to convert the ALWIP mode to a non-ALWIP intra-coding mode.

[0135] In the above examples, an MPM list is created for signaling the ALWIP mode. The creation of the MPM list includes checking the prediction mode(s) of the adjacent block(s). When the neighbor block prediction mode is not the ALWIP mode, the neighbor block prediction mode is to be mapped to the ALWIP mode using a mapping table. When the neighbor block prediction mode is the ALWIP mode, access to the width and height of the neighbor block is needed to verify that the same set of matrices is applied by the current and neighbor block. The process of generating the MPM list is complex and can be simplified.

[0136] In addition, for signaling the non-ALWIP intra prediction mode, when encoding an adjacent block in ALWIP mode, a lookup table is used to map the ALWIP mode of the neighboring block to the non-ALWIP intra prediction mode. However, it may not be necessary for a neighboring block to convert the ALWIP mode to a non-ALWIP mode.

[0137] Further, the ALWIP mode is not applied to intra chroma block prediction. However, when using a derived mode for a chrominance block and encoding a luminance block adjacent to the chrominance block in ALWIP mode, the ALWIP mode of the adjacent luminance block needs to be converted to a non-ALWIP intra prediction mode. This process is complex, and it can also be simplified.

[0138] Aspects of the invention provide simplified signaling for ALWIP modes and other modes. The embodiments may be used singly or in combination in any order.

[0139] According to aspects of the invention, signaling or reconstruction of the ALWIP mode index for the current block is performed without checking the intra prediction mode(s) of the adjacent block(s) of the current block. In an embodiment, signaling and/or reconstruction may be performed without checking the intra prediction modes of any neighboring blocks of the current block. For example, according to FIG. 10, the neighbor blocks may be a left neighbor block A and a top neighbor block B. The left neighbor block A is adjacent to the current block at the lower left corner. In this example, signaling and/or reconstruction can be performed without checking the intra prediction modes of the left neighbor block A and the top neighbor block B.

[0140] In an embodiment, the ALWIP mode index is signaled directly. The ALWIP mode index may be transmitted directly with a codeword, such as a truncated binary codeword, a fixed length codeword, or a truncated unary codeword. For example, the ALWIP mode index is signaled with a five-bit fixed length codeword. In another example, a subset of the ALWIP modes, eg, the K1 ALWIP modes, are signaled with an M1-bit fixed-length codeword while signaling the remaining ALWIP modes with an M2-bit fixed-length codeword. In the above examples, K1, M1 and M2 are non-negative integers.

[0141] In an embodiment, the ALWIP mode index is signaled without MPM listing or MPM flag signaling. For example, a truncated binary or fixed length codeword is used to signal the ALWIP mode index.

[0142] In an embodiment, when the current block is encoded by ALWIP, in the MPM list of the current block, the candidate modes are fixed regardless of the intra prediction mode(s) of the adjacent block(s) of the current block. In such an embodiment, the positions of neighboring blocks may be identical to those used for prediction in non-ALWIP modes (eg, neighboring blocks A and B in FIG. 10). In the example, when encoding the current block with ALWIP, the candidate modes in the MPM list of the current block and the order of the candidate modes are fixed, regardless of the intra prediction mode(s) of the neighboring block(s) of the current block. In such an example, the positions of adjacent blocks may be identical to those used for non-ALWIP mode prediction (eg, adjacent blocks A and B in FIG. 10). In another example, when the current block is encoded with ALWIP, the candidate modes and/or the order of the candidate modes in the MPM list of the current block depend on the width and/or height of the current block. Candidate modes and/or order of candidate modes in the MPM list of the current block in some embodiments may depend only on the width and/or height of the current block.

[0143] According to some embodiments, the total number of ALWIP modes is a power of 2, such as N=2 ^k , where N is the total number of ALWIP modes. K is a non-negative integer, such as 0 to 5, etc.

[0144] In an embodiment, the value of K depends on the block size of the current block. For example, the block size of the current block can be indicated by (i) the width of the block, (ii) the height of the block, (iii) the average of the width and height of the block, (iv) the minimum value of the width and height of the block, (v) the maximum value of the width and height of the block, (vi) block area size or (vii) block aspect ratio.

[0145] According to aspects of the invention, when generating the MPM list of a current block encoded in a non-ALWIP intra prediction mode, the prediction mode of one or more neighboring blocks of the current block is marked as unavailable or fixed mode when the prediction mode of the neighboring block is ALWIP mode. In an example, the position of one or more neighboring blocks may be identical to positions used for prediction in other non-ALWIP modes (eg, neighboring blocks A and B in FIG. 10). In an embodiment, when generating the MPM list of a current block that is encoded in a non-ALWIP intra prediction mode, the prediction mode of one or more neighboring blocks of the current block is marked as a flat intra prediction mode (Planar intra). In an embodiment, when compiling the MPM list of a current block that is encoded by a non-ALWIP intra prediction mode, the prediction mode of one or more adjacent blocks of the current block is marked as DC intra prediction mode. In an embodiment, when generating the MPM list of a current block that is encoded by a non-ALWIP intra coding mode, the neighbor block prediction mode of the current block is marked as flat mode, DC mode, horizontal intra prediction mode, or vertical intra prediction mode.

[0146] According to aspects of the invention, to generate the MPM list of the current block, which is encoded by the ALWIP mode, the prediction mode of one or more neighboring blocks of the current block is marked as an available ALWIP mode or a default ALWIP mode. In an embodiment, when encoding an adjacent block with ALWIP, its prediction mode is marked as available, and when encoding a neighboring block with a non-ALWIP mode, its prediction mode is marked as ALWIP mode. set by default.

[0147] In an embodiment, when encoding the current block with ALWIP to generate the MPM list of the current block, the neighboring block prediction mode is converted to the ALWIP prediction mode when the prediction mode is a non-ALWIP mode. For example, the prediction mode is converted to the ALWIP prediction mode with the mode index k, the value of which is a non-negative integer, and it is forbidden to exceed the maximum allowable value of the ALWIP mode index.

[0148] In an embodiment, when encoding the current block with ALWIP, to construct the MPM list of the current block, the neighbor block prediction mode of the current block is marked as unavailable when the prediction mode is not the ALWIP mode.

[0149] In an embodiment, when encoding the current block with ALWIP, the MPM list size is set to 1. The left (or top) neighboring block intra prediction mode may be included in the MPM list when the intra prediction mode is the ALWIP mode. When the left and top adjacent blocks are encoded in a non-ALWIP mode, one ALWIP mode. the default is included in the MPM list. In the example, the default ALWIP mode is set to flat mode (for example, mode 0).

[0150] In an embodiment, when encoding the current block with ALWIP, the MPM list size is set to 2. The left (or top) neighboring block intra prediction mode may be included in the MPM list if the intra prediction mode is the ALWIP mode. When encoding the left (or top) adjacent block with a non-ALWIP mode, the default ALWIP mode is included in the MPM list. In the example, the default ALWIP mode is fixed, regardless of the block size of the current block. In an example, when the MPM flag indicates the intra prediction mode of the current block in the MPM list, for example, the MPM flag is true, another flag is signaled to indicate which candidate MPM is selected from the MPM list for the current block.

[0151] According to aspects of the invention, the neighbor position used to obtain the ALWIP mode MPM list is similar to the non-ALWIP mode position. In an embodiment for the ALWIP mode, the position(s) of the neighboring block(s) used to obtain the MPM list is(are) adjacent to the top right or bottom left corner of the current block, as shown in FIG. ten.

[0152] According to aspects of the invention, the size of the MPM list for the ALWIP mode is independent of the encoded information included, for example, in the encoded video sequence. The encoded information may include, but is not limited to, one or more intra prediction modes of one or more neighboring blocks, a reference stream index of one or more neighboring blocks, an ALWIP flag of one or more neighboring blocks.

[0153] In an embodiment, when encoding the current block with ALWIP and the top right and bottom left neighboring blocks with non-ALWIP mode, no MPM list is generated and the ALWIP mode index is directly signaled for the current block.

[0154] In an embodiment, when encoding the current block with ALWIP and at least one of the neighboring blocks of the current block with ALWIP, the size of the MPM list for the current block is given by a non-negative integer, such as 1 or 2.

[0155] According to aspects of the invention, ALWIP is not applied to the chrominance block. Thus, when a luma block associated with the current chrominance block (eg, a co-located luma block) is encoded by ALWIP and a derived mode is applied to the current chroma block, the non-ALWIP default mode is applied to the current chroma block. In one embodiment, the default non-ALWIP mode is flat mode. In another embodiment, the default non-ALWIP mode is DC mode.

[0156] According to aspects of the invention, when the current chrominance block is associated with a plurality of luminance blocks, for example, when the current chrominance block is associated with a plurality of co-located luma blocks, and a derived mode is applied to the current block, the plurality of luma blocks is checked to encode one of the set associated luma blocks in non-ALWIP intra prediction mode.

[0157] In an embodiment, when one of the plurality of adjacent luma blocks is encoded in a non-ALWIP intra prediction mode, the non-ALWIP intra prediction mode is applied as the intra prediction mode of the current chrominance block.

[0158] In an embodiment, when none of the plurality of associated luma blocks (e.g., co-spaced luma blocks) is encoded in a non-ALWIP intra prediction mode, the default non-ALWIP intra prediction mode is applied as the mode internal prediction of the current chrominance blocks.

[0159] In FIG. 13 shows a flowchart of the operations of a process (1300) according to an embodiment of the invention. Process (1300) may be used in reconstructing an intra-coded block to generate a prediction block for the block to be reconstructed. In various embodiments, the process (1300) is performed by a processing circuit, for example, a processing circuit in terminal devices (110), (120), (130) and (140), a processing circuit that performs the functions of a video encoder (203), a processing circuit, that performs the functions of a video decoder (210), a processing circuit that performs the functions of a video decoder (310), a processing circuit that performs the functions of a video encoder (403), and the like. In some embodiments, the process (1300) is implemented in program instructions, such that when the processing circuit executes the program instructions, the processing circuit executes the process (1300). The process starts at step (S1301) and proceeds to (S1310).

[0160] In step (S1310), the process (1300) decodes the prediction information for the current block in the current picture that is included in the encoded video sequence. The prediction information indicates whether the current block is encoded using affine linear weighted intra prediction (ALWIP). In response to the prediction information indicating coding of the current block using ALWIP, the process (1300) proceeds to step (S1320).

[0161] In step (S1320), the process (1300) determines the ALWIP mode index regardless of the prediction modes of neighboring blocks adjacent to the current block. The ALWIP mode index indicates one of a plurality of ALWIP modes. Then, the process (1300) proceeds to step (S1330).

[0162] In step (S1330), process (1300) reconstructs the current block according to one of the plurality of ALWIP modes. Then, the process (1300) proceeds to step (S1399) and ends.

[0163] In an embodiment, the ALWIP mode index is a truncated binary codeword, a fixed length codeword, or a truncated unary codeword.

[0164] In an embodiment, in response to prediction information indicating that the current block is encoded using ALWIP, process (1300) generates a list of candidate modes including at least one fixed candidate mode. At least one fixed potential mode is a predefined subset of the set of ALWIP modes.

[0165] In an embodiment, the total number of modes in the ALWIP mode set is a power of 2.

[0166] In an embodiment, in response to prediction information indicating that the current block is not ALWIP coded, the process (1300) determines whether one of the neighboring blocks is ALWIP coded. In response to one of the neighboring blocks being encoded using ALWIP, the process (1300) generates a list of candidate modes based on (i) a predetermined intra prediction mode or (ii) another neighboring block's intra prediction mode of the adjacent blocks.

[0167] In an embodiment, the predetermined prediction mode is a flat intra prediction mode, a DC intra prediction mode, a horizontal intra prediction mode, or a vertical intra prediction mode.

[0168] In an embodiment, process (1300) makes one of the neighboring blocks unavailable in response to one of the neighboring blocks being encoded using ALWIP.

[0169] In an embodiment, in response to prediction information indicating that the current block is encoded using ALWIP, and when using a derived mode for the associated chrominance block associated with the current block, the process (1300) sets the prediction mode of the associated chrominance block as a predetermined mode internal prediction.

[0170] In FIG. 14 shows a flowchart of the operations of a process (1400) according to an embodiment of the invention. Process (1300) may be used in reconstructing an intra-coded block to generate a prediction block for the block to be reconstructed. In various embodiments, the process (1400) is performed by a processing circuit, for example, a processing circuit in terminal devices (110), (120), (130) and (140), a processing circuit that performs the functions of a video encoder (203), a processing circuit, that performs the functions of a video decoder (210), a processing circuit that performs the functions of a video decoder (310), a processing circuit that performs the functions of a video encoder (403), and the like. In some embodiments, the process (1400) is implemented in program instructions, such that when the processing circuitry executes the program instructions, the processing circuitry executes the process (1400). The process starts at step (S1401) and proceeds to (S1410).

[0171] In step (S1410), the process (1400) decodes the prediction information for the current block in the current picture that is included in the encoded video sequence. The prediction information indicates the coding of the current block using affine linear weighted intra prediction (ALWIP). Then, the process (1400) proceeds to step (S1420).

[0172] In step (S1420), the process (1400) determines whether an adjacent block adjacent to the current block is encoded using ALWIP. In response to no neighbor block coding using ALWIP, the process (1400) proceeds to step (S1430).

[0173] In step (S1430), the process (1400) generates a list of candidate modes based on (i) a predetermined ALWIP mode or (ii) an ALWIP mode of another neighboring block. Next, the process (1400) proceeds to step (S1440).

[0174] In step (S1440), process (1400) reconstructs the current block based on the list of candidate modes. Then, the process (1400) proceeds to step (S1499) and ends.

[0175] In an embodiment, the process (1400) sets the neighbor block as unavailable in response to the fact that the neighbor block is not encoded using ALWIP.

[0176] In an embodiment, an adjacent block is adjacent to the current block in the upper right or lower left corner.

[0177] In an embodiment, the size of the candidate mode list is based on the encoded neighbor block information included in the encoded video sequence.

[0178] In an embodiment, the prediction information indicates that a chrominance block of the current block is associated with a plurality of luminance blocks, and a process (1400) determines whether the luminance block of the plurality of luma blocks is encoded in a non-ALWIP intra prediction mode. In response to encoding a luma block in a non-ALWIP intra prediction mode, process (1400) determines the chrominance block prediction mode of the current block as a non-ALWIP luminance block intra prediction mode.

[0179] In an embodiment, the prediction information indicates that a chrominance block of the current block is associated with a plurality of luminance blocks, and a process (1400) determines whether the luminance block of the plurality of luma blocks is encoded in a non-ALWIP intra prediction mode. In response to each of the plurality of luma blocks being encoded using ALWIP, the process (1400) determines the prediction mode of the chrominance block of the current block as a predetermined intra prediction mode.

[0180] Computer system

[0181] The above methods may be implemented in computer software using computer-readable instructions and physically stored on one or more computer-readable media. For example, in FIG. 15 shows a computer system (1500) suitable for implementing some embodiments of the disclosed invention.

[0182] Computer software may be coded using any suitable machine code or computer language that may be assembled, compiled, linked, or similarly processed to create code containing instructions that can be executed directly, or through interpretation, execution of microcode, etc. .p., one or more computer central processing units (CPU, central processing units), graphic processors (GPU, Graphics Processing Units), etc.

[0183] The instructions may be executed on various types of computers or components thereof, including, for example, personal computers, tablet computers, servers, smartphones, gaming devices, IoT devices, and the like.

[0184] The computer system components (1500) shown in FIG. 15 are illustrative in nature and are not intended to impose any limitation on the scope of application or functionality of computer software implementing embodiments of the present invention. The configuration of the components should also not be interpreted as having any dependency or requirement in connection with any one or combination of the components shown in the illustrative embodiment of the computer system (1500).

[0185] The computer system (1500) may include some human interface input devices. Such an input device may be responsible for input by one or more users through, for example, tactile input (e.g., keystrokes, waving, glove movements), audio input (e.g., voice, claps), visual input (e.g., gestures), olfactory input (not shown). Interface devices may also be used to capture certain media not necessarily directly related to conscious human input, such as sound (e.g. speech, music, external sound), images (e.g. scanned images, photographic images received from a still camera), video (eg, 2D video, 3D video including stereoscopic video).

[0186] The input human interface of the device may include one or more devices (one of each shown): keyboard (1501), mouse (1502), touch pad (1503), touch screen (1510), information glove (not shown) , joystick (1505), microphone (1506), scanner (1507), camera (1508).

[0187] The computer system (1500) may also include some human interface output devices. Such output devices may stimulate the senses of one or more users through, for example, tactile output, sound, light, and smell/taste. Such output devices may include tactile output devices (e.g., haptic feedback via touch screen (1510), data glove (not shown), or joystick (1505), but may also be tactile feedback devices that do not serve as input devices) , audio output devices (for example: speakers (1509), headphones (not shown)), visual output devices (for example, screens (1510), including CRT screens, LCD screens, plasma screens, OLED screens, each with touch screen input capabilities, each with or without tactile feedback capabilities, some of which are capable of 2D visual output or more than 3D output through, for example, stereographic output; virtual reality glasses (not shown), holographic displays, and smoke tanks (not shown)) and printers (not shown). These visual output devices (eg screens (1510)) can be connected to the system bus (1548) via a graphics adapter (1550).

[0188] The computer system (1500) may also include human accessible storage devices and associated media, such as optical media including CD/DVD ROM/RW (1520) with CD/DVD media (1521), etc. .p., flash memory cards (1522), removable hard drive or solid state drive (1523), conventional magnetic media such as tape and floppy disk (not shown), dedicated ROM/ASIC/PLD based devices such as security hardware keys (not shown) and the like.

[0189] Those skilled in the art should also understand that the term "computer-readable media" as used in connection with the invention disclosed herein does not encompass transmission media, carrier waves, or other short-term signals.

[0190] The computer system (1500) may also include an interface (1554) to one or more communication networks (1555). One or more communication networks (1555) may be, for example, wireless, wired, optical. One or more communication networks (1555) may additionally be local, wide area, metropolitan, transport and industrial, real time, delay tolerant, and so on. Examples of one or more communications networks (1555) include local area networks such as Ethernet, wireless LANs, cellular networks including GSM, 3G, 4G, 5G, LTE, and the like, digital wide area wired or wireless television networks , including cable TV, satellite TV and terrestrial TV, transport and industrial include CANBus, etc. Some networks typically require external network interface adapters that are connected to some general purpose data ports or peripheral buses (1549) (for example, computer system USB ports (1500)); others are typically built into the core of the computer system (1500) by connecting to a system bus as described below (eg, 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 (1500) can communicate with other entities. Such communication may be unidirectional with receive-only capability (eg broadcast), unidirectional with transmit-only capability (eg CANbus to some CANbus devices), or bidirectional, eg to other computer systems using a local area network or a wide area digital network. Several protocols and protocol stacks may be used on each of these networks and the network interfaces described above.

[0191] The aforementioned human interface devices, human accessible storage devices, and network interfaces can be connected to the core (1540) of the computer system (1500).

[0192] The core (1540) may include one or more central processing units (CPUs) (1541), graphics processing units (GPUs) (1542), specialized programmable processing modules in the form of Field Programmable Gate Areas (FPGAs). ) (1543), hardware accelerators (1544) for some tasks, etc. These devices, together with read-only memory (ROM) (1545), random access memory (1546), high capacity internal storage such as user-inaccessible internal hard drives, SSD, etc. (1547) can be connected via the system bus (1548). In some computer systems, the system bus (1548) may be available in the form of one or more physical connectors to allow for expansions with additional CPUs, GPUs, or the like. Peripherals can be connected either directly to the system bus (1548) of the kernel, or via a peripheral bus (1549). Peripheral bus architectures include PCI, USB, and the like.

[0193] CPUs (1541), GPUs (1542), FPGAs (1543), and accelerators (1544) may execute some instructions that together may constitute the aforementioned computer code. This computer code may be stored in ROM (1545) or RAM (1546). Transient data may also be stored in RAM (1546), while persistent data may be stored in, for example, an internal mass storage (1547). Fast storage and retrieval from any storage device can be achieved through the use of cache memory, which can be closely associated with one or more CPU (1541), GPU (1542), mass storage (1547), ROM (1545), RAM (1546), etc.

[0194] Computer-readable media may store computer code for performing various computer-implemented operations. The media and computer code may be specially created for the purposes of the present invention or may be well known and available to those skilled in the art of computer software.

[0195] By way of example, and not limitation, a computer system having an architecture (1500), and in particular a core (1540), can provide functionality through execution by processor(s) (including(and) CPU, GPU, FPGAs, accelerators, etc.) software embodied in one or more tangible computer-readable media. Such computer-readable media can be media associated with the user-accessible mass storage described above, as well as some persistent storage in the kernel (1540), such as internal mass storage (1547) or ROM (1545). Software implementing various embodiments of the present invention may be stored on such devices and executed by the kernel (1540). The computer-readable medium may include one or more memory devices or chips, in accordance with specific needs. The software may direct the core (1540), and in particular its processors (including CPUs, GPUs, FPGAs, and the like), to execute specific processes or specific portions of the specific processes described herein, including setting data structures stored in RAM (1546) , and modifying such data structures according to processes defined by the software. Additionally or alternatively, the computer system may provide functionality through logic hardwired or otherwise embodied in circuitry (e.g., an accelerator (1544)) that may operate in place of or in conjunction with software to perform specific processes or specific portions of the specific processes described herein. A reference to software may cover logic, and vice versa when appropriate. Reference to computer-readable media may encompass a circuit (eg, an integrated circuit (IC)) where software is stored for execution, a circuit embodying logic for execution, or both, as appropriate. The present invention encompasses any suitable combination of hardware and software.

[0196] Although several illustrative embodiments are described here, changes, permutations, and various equivalents for substitution are possible within the scope of the invention. Thus, those skilled in the art can provide numerous systems and methods that, although not explicitly shown or described herein, embody the principles of the invention and thus fall within its spirit and scope.

Appendix A: Abbreviations

ALWIP (or LWIP): Affine Linear Weighted Intra Prediction

AMVP: Advanced Motion Vector Prediction

ASIC: Application Specific Integrated Circuit

ATMVP: Alternative/Advanced Temporal Motion Vector Prediction

BMS: a set of standards

BV: block vector

CANBus: controller network bus

SW: coding block

CD: CD

CPR: Current Image Reliance

CPU: central processing units

CRT: kinescope

CTB: coding tree block

CTU: coding tree unit

CU: coding unit

DM: derived mode

DPB: decoder picture buffer

DVD: Digital Video Disc

FPGA: Field Programmable Gate Arrays

GOP: groups of images

GPU: GPUs

GSM: Global System for Mobile Communications

HDR: High (extended) dynamic range

HEVC: High Performance Video Coding

HRD: Hypothetical Reference Decoder

IBC: intra-block copy

IC: integrated circuit

ISP: inner cell

JEM: collaborative research model

JVET: Joint Video Research Group

LAN: local area network

LCD: liquid crystal display

LTE: a project for the long-term development of communication systems

MIP: Matrix Intra Prediction

MRM: most probable mode

MV: motion vector

OLED: organic light emitting diode

RW: prediction block

PCI: Peripheral Component Interconnect

PDPC: Positional Prediction Combination

PLD: Programmable Logic Device

PU: prediction unit

RAM: random access memory

ROM: Read Only Memory

SCC: Screen Content Coding

SDR: standard dynamic range

SEI: Additional Improvement Information

SNR: signal to noise ratio

SSD: solid state drive

TU: conversion unit

USB: Universal Serial Bus

VUI: video suitability information

VVC: Universal Video Coding

WAIP: Wide Angle Intra Prediction.

Claims (43)

1. A video decoding method in a decoder, in which: decoding prediction information for the current block in the current picture that is part of the encoded video sequence, the prediction information indicating whether the current block is encoded using matrix-based intra prediction (MIP); in response to prediction information indicating that the current block is encoded using MIP, determining a MIP mode index, wherein the MIP mode index indicates one of the plurality of MIP modes, and reconstructing the current block according to said one of the plurality of MIP modes. 2. The method of claim 1, wherein the MIP mode index is one of a truncated binary codeword, a fixed length codeword, or a truncated unary codeword. 3. The method according to claim 1 or 2, in which: in response to prediction information indicating encoding of the current block using MIP, generating a candidate mode list including at least one fixed candidate mode, wherein the candidate mode list is a predetermined subset of the plurality of MIP modes. 4. The method of claim 1 or 2, wherein the total number of the plurality of MIP modes is a power of 2. 5. The method according to claim 1 or 2, in which: in response to prediction information indicating that the current block is not encoded using MIP, determining whether one of the plurality of neighboring blocks is encoded using MIP, and if one of the neighboring blocks is encoded using MIP, a list of candidate modes is formed based on (i) a predetermined intra prediction mode or (ii) an intra prediction mode of another neighboring block from neighboring blocks. 6. The method of claim 5, wherein the predetermined intra prediction mode is one of Planar intra prediction mode, DC intra prediction mode, horizontal intra prediction mode, or vertical intra prediction mode. 7. The method of claim 5, wherein generating the list also includes: if one of the neighboring blocks is encoded using MIP, setting that one of the neighboring blocks as unavailable. 8. The method according to claim 1 or 2, in which: in response to prediction information indicating encoding the current block using MIP and applying a derived mode to the chrominance block associated with the current block, setting the prediction mode of the associated chrominance block to a predetermined intra prediction mode. 9. The method according to claim 1 or 2, in which: in response to the fact that the current block is not encoded using MIP, but one of the plurality of neighboring blocks is encoded using MIP, determining the potential intra prediction mode for the current block as a flat intra prediction mode, and reconstructing the current block according to the planar intra prediction mode. 10. A video decoding method in a decoder, wherein: decoding prediction information for the current block in the current picture that is part of the encoded video sequence, the prediction information indicating that the current block is encoded using matrix-based intra prediction (MIP); determining whether an adjacent block adjacent to the current block is encoded using MIP; if the adjacent block is not encoded using MIP, generating a list of candidate modes based on (i) a predetermined MIP mode or (ii) another neighbor block's MIP mode, and reconstructing the current block based on the list of potential modes. 11. The method of claim 10, wherein generating the list also includes: in response to the fact that the neighboring block is not encoded using MIP, setting the neighboring block as unavailable. 12. The method of claim. 10 or 11, in which the neighboring block is adjacent to the upper right or lower left corner of the current block. 13. The method of claim 10 or 11, wherein the size of the candidate mode list is based on encoded neighbor block information included in the encoded video sequence. 14. The method of claim 10 or 11, wherein the prediction information indicates that a chrominance block of the current block is associated with a plurality of luminance blocks, and the method also includes: determining whether a luminance block of the plurality of luminance blocks is encoded in a non-MIP intra prediction mode; and in response to the luma block being encoded in a non-MIP intra prediction mode, determining a chroma block prediction mode of the current block as a non-MIP luminance block intra prediction mode. 15. The method according to claim 14, in which: in response to each of the plurality of luma blocks being encoded using MIP, determining a chrominance block prediction mode of the current block as a predetermined intra prediction mode. 16. A video decoding device, including a processing circuit configured to perform the method according to any one of paragraphs. 1-9. 17. A video decoding device, including a processing circuit configured to perform the method according to any one of paragraphs. 10-15.

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