Method and device for video processing and medium

Abstract

Embodiments of the present disclosure provide a solution for video processing. A method for video processing is proposed. The method comprises: for a conversion between a video unit of a video and a bitstream of the video unit, performing refinement on prediction or reconstruction of the video unit by applying a filter for the video unit; and performing a conversion based on the refined prediction or the refined reconstruction.

Description

Technical Field

[0001] The embodiments of this disclosure generally relate to video processing techniques, and more specifically, to filter-based prediction for video encoding and decoding. Background Technology

[0002] Today, digital video capabilities are being applied to all aspects of people's lives. Various video compression technologies have been proposed for video encoding / decoding, such as MPEG-2, MPEG-4, ITU-TH.263, ITU-TH.264 / MPEG-4 Part 10 Advanced Video Codec (AVC), ITU-TH.265 High Efficiency Video Codec (HEVC) standard, and Multi-Functional Video Codec (VVC) standard. However, the encoding and decoding efficiency of video encoding and decoding technologies is generally expected to be further improved. Summary of the Invention

[0003] Embodiments of this disclosure provide a solution for video processing.

[0004] In a first aspect, a method for video processing is proposed. This method includes: conversion between video units and bitstreams of video units; refining the prediction or reconstruction of video units by applying filters to them; and performing a conversion based on the refined prediction or reconstruction. In this manner, encoding / decoding efficiency and performance can be improved.

[0005] In a second aspect, an apparatus for video processing is proposed. The apparatus includes a processor and a non-transitory memory having instructions thereon, wherein the instructions, when executed by the processor, cause the processor to perform the method according to the first aspect of this disclosure.

[0006] In a third aspect, a non-transitory computer-readable storage medium is proposed. This non-transitory computer-readable storage medium stores instructions that cause a processor to perform the method according to the first aspect of this disclosure.

[0007] In a fourth aspect, another non-transitory computer-readable recording medium is proposed. This non-transitory computer-readable recording medium stores a bitstream of video generated by a method performed by an apparatus for video processing. The method includes: refining the prediction or reconstruction of video cells by applying filters to the video cells; and generating a bitstream based on the refined prediction or refined reconstruction.

[0008] In the fifth aspect, a method for storing a bitstream of video is proposed. This method includes: refining the prediction or reconstruction of video cells by applying filters to the video cells; generating a bitstream based on the refined prediction or reconstruction; and storing the bitstream in a non-transitory computer-readable recording medium.

[0009] This synopsis aims to present, in a simplified form, the selected concepts further described below in the detailed embodiments. This synopsis is not intended to identify key or essential features of the claimed subject matter, nor is it intended to limit the scope of the claimed subject matter. Attached Figure Description

[0010] The above and other objects, features, and advantages of exemplary embodiments of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. In the exemplary embodiments of the present disclosure, the same reference numerals generally refer to the same components.

[0011] Figure 1 A block diagram of an example video codec system according to some embodiments of the present disclosure is shown; Figure 2 A block diagram of a first example video encoder according to some embodiments of the present disclosure is shown; Figure 3 A block diagram of an example video decoder according to some embodiments of the present disclosure is shown; Figure 4 An example of an encoder block diagram is shown; Figure 5 67 intra-frame prediction modes are shown; Figure 6 Reference samples for wide-angle intra-frame prediction are shown; Figure 7 The discontinuity problem is shown when the orientation exceeds 45°; Figure 8 The MMVD search point is shown; Figure 9 This is a schematic diagram of the symmetrical MVD model; Figure 10 The extended CU region used in BDOF is shown; Figure 11 An affine motion model based on control points is shown; Figure 12 The affine MVF for each sub-block is shown; Figure 13 The location of the inherited affine motion prediction value is shown; Figure 14 This demonstrates the inheritance of control point motion vectors; Figure 15The locations of candidate positions for the constructed affine Merge pattern are shown; Figure 16 This is a schematic diagram illustrating the use of motion vectors in the proposed combination method; Figure 17 The sub-block MV VSB and pixels are shown. ; Figure 18A This shows the spatial neighbor blocks used by ATVMP; Figure 18B The paper demonstrates how to derive the motion field of a sub-CU by applying motion shifts from spatial neighbors and scaling motion information from the corresponding co-located sub-CUs. Figure 19 Position lighting compensation is shown; Figure 20 This indicates that no downsampling was performed on the short side; Figure 21 This shows the refinement of motion vectors on the decoding side; Figure 22 The diamond-shaped area in the search region is shown; Figure 23 The locations of the spatial merge candidates are shown; Figure 24 The candidate pairs considered for redundancy checks of spatial merge candidates are shown. Figure 25 This is a schematic diagram of motion vector scaling for temporal merge candidates; Figure 26 The candidate positions for time-domain Merge candidates C0 and C1 are shown; Figure 27 The VVC spatial neighboring blocks of the current block are shown; Figure 28 This is a schematic diagram of the virtual block in the i-th round of search; Figure 29 An example of GPM partitioning grouped at the same angle is shown; Figure 30 The unidirectional prediction MV selection for geometric segmentation patterns is shown; Figure 31 The bending weights using the geometric segmentation pattern are shown. An example of generation; Figure 32 The spatial neighboring blocks used to derive spatial merge candidates are shown; Figure 33 This illustrates template matching performed on the search area surrounding the initial MV; Figure 34 This is a schematic diagram of a sub-block in an OBMC application; Figure 35The location, type, and transformation type of the SBT are shown; Figure 36 The neighboring samples used to calculate SAD are shown; Figure 37 The neighboring samples used to calculate SAD for sub-CU level motion information are shown; Figure 38 The sorting process is shown; Figure 39 The recording process in the encoder is shown; Figure 40 The reordering process in the decoder is shown; Figure 41 This is a schematic diagram of the extended reference area; Figure 42 The IBC reference area is shown, depending on the current CU location; Figure 43 An example of symmetry is shown in a screen content image; Figure 44A This is a diagram illustrating the adjustment of BV for horizontal flipping; Figure 44B This is a diagram illustrating the BV adjustment for vertical flipping; Figure 45 The intra-frame template matching search area used is shown; Figure 46 This is a schematic diagram of the template area; Figure 47 The spatial portion of the convolution filter is shown; Figure 48 The reference region (and its filling) used to derive the filter coefficients is shown. Figure 49 Four Sobel-based gradient modes for GLM are shown; Figures 50A to 50G The neighboring samples used in the filter are shown; Figures 51A to 51E A template for deriving the parameters of the filter is shown; Figures 52A to 52F A combined template for the parameters used to derive the filter is shown; Figure 53 An L-shaped template used to derive the parameters of the filter is shown; Figure 54 The non-adjacent templates used to derive the filter parameters are shown; Figure 55 A flowchart of a method for video processing according to embodiments of the present disclosure is shown; and Figure 56 A block diagram of a computing device in which various embodiments of the present disclosure may be implemented is shown.

[0012] In all accompanying drawings, the same or similar reference numerals usually refer to the same or similar elements. Detailed Implementation

[0013] The principles of this disclosure will now be described with reference to some embodiments. It should be understood that these embodiments are described for illustrative purposes only and to help those skilled in the art understand and implement this disclosure, and do not imply any limitation on the scope of this disclosure. The disclosure described herein can be implemented in various ways besides the methods described below.

[0014] In the following description and claims, unless otherwise defined, all scientific and technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains.

[0015] The terms "an embodiment," "embodiment," "example embodiment," etc., used in this disclosure refer to embodiments that may include specific features, structures, or characteristics, but not every embodiment is required to include that specific feature, structure, or characteristic. Furthermore, these phrases do not necessarily refer to the same embodiment. Additionally, when a specific feature, structure, or characteristic is described in conjunction with an example embodiment, whether explicitly described or not, it is believed that such a feature, structure, or characteristic affecting its relation to other embodiments is within the knowledge of those skilled in the art.

[0016] It should be understood that although the terms “first” and “second”, etc., can be used to describe various elements, these elements should not be limited to these terms. These terms are used only to distinguish one element from another. For example, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element, without departing from the scope of the exemplary embodiments. As used herein, the term “and / or” includes any and all combinations of one or more of the listed terms.

[0017] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. As used herein, the singular forms “a,” “an,” and “the” are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising,” “including,” and / or “having” as used herein mean the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof.

[0018] Example Environment Figure 1This is a block diagram illustrating an example video encoding / decoding system 100 from which the techniques of this disclosure may be utilized. As shown, the video encoding / decoding system 100 may include a source device 110 and a destination device 120. The source device 110 may also be referred to as a video encoding device, and the destination device 120 may also be referred to as a video decoding device. In operation, the source device 110 may be configured to generate encoded video data, and the destination device 120 may be configured to decode the encoded video data generated by the source device 110. The source device 110 may include a video source 112, a video encoder 114, and an input / output (I / O) interface 116.

[0019] Video source 112 may include sources such as video capture devices. Examples of video capture devices include, but are not limited to, interfaces for receiving video data from video content providers, computer graphics systems for generating video data, and / or combinations thereof.

[0020] Video data may include one or more images. Video encoder 114 encodes the video data from video source 112 to generate a bitstream. The bitstream may include a sequence of bits forming a codec representation of the video data. The bitstream may include codec images and associated data. The codec images are codec representations of images. The associated data may include sequence parameter sets, image parameter sets, and other syntax structures. I / O interface 116 may include a modulator / demodulator and / or a transmitter. Encoded video data can be directly transmitted to destination device 120 via network 130A through I / O interface 116. Encoded video data may also be stored on storage medium / server 130B for access by destination device 120.

[0021] The destination device 120 may include an I / O interface 126, a video decoder 124, and a display device 122. The I / O interface 126 may include a receiver and / or a modem. The I / O interface 126 may acquire encoded video data from the source device 110 or the storage medium / server 130B. The video decoder 124 may decode the encoded video data. The display device 122 may display the decoded video data to a user. The display device 122 may be integrated with the destination device 120, or it may be external to the destination device 120, which is configured to interface with an external display device.

[0022] The video encoder 114 and the video decoder 124 can operate according to video compression standards, such as the High Efficiency Video Codec (HEVC) standard, the Multi-Functional Video Codec (VVC) standard, and other existing and / or further standards.

[0023] Figure 2This is a block diagram illustrating an example of a video encoder 200 according to some embodiments of the present disclosure. The video encoder 200 may be... Figure 1 An example of a video encoder 114 in system 100 is shown.

[0024] The video encoder 200 can be configured to implement any or all of the technologies disclosed herein. Figure 2 In the example, the video encoder 200 includes multiple functional components. The techniques described in this disclosure can be shared among the various components of the video encoder 200. In some examples, the processor can be configured to perform any or all of the techniques described in this disclosure.

[0025] In some embodiments, the video encoder 200 may include a segmentation unit 201, a prediction unit 202, a residual generation unit 207, a transform unit 208, a quantization unit 209, an inverse quantization unit 210, an inverse transform unit 211, a reconstruction unit 212, a buffer 213, and an entropy coding unit 214. The prediction unit 202 may include a mode selection unit 203, a motion estimation unit 204, a motion compensation unit 205, and an intra-frame prediction unit 206.

[0026] In other examples, the video encoder 200 may include more, fewer, or different functional components. In one example, the prediction unit 202 may include an intra-block copy (IBC) unit. The IBC unit can perform prediction in an IBC mode, where at least one reference picture is the picture containing the current video block.

[0027] Furthermore, although some components (such as motion estimation unit 204 and motion compensation unit 205) can be integrated, for interpretable purposes, these components are... Figure 2 The examples are shown separately.

[0028] The segmentation unit 201 can segment an image into one or more video blocks. The video encoder 200 and the video decoder 300 can support various video block sizes.

[0029] The mode selection unit 203 can select one of several codec modes (intra-frame codec or inter-frame codec) based, for example, on the error result, and provide the resulting intra-frame or inter-frame codec block to the residual generation unit 207 to generate residual block data, and to the reconstruction unit 212 to reconstruct the coded block for use as a reference image. In some examples, the mode selection unit 203 can select an intra-frame / inter-frame joint prediction (CIIP) mode, where prediction is based on inter-frame prediction signals and intra-frame prediction signals. In the case of inter-frame prediction, the mode selection unit 203 can also select a resolution for the block based on the motion vector (e.g., sub-pixel precision or integer pixel precision).

[0030] To perform inter-frame prediction on the current video block, motion estimation unit 204 can generate motion information for the current video block by comparing one or more reference frames from buffer 213 with the current video block. Motion compensation unit 205 can determine the predicted video block for the current video block based on the motion information and decoded samples of images from buffer 213 other than the image associated with the current video block.

[0031] The motion estimation unit 204 and the motion compensation unit 205 can perform different operations on the current video block, for example, depending on whether the current video block is in an I-strip, P-strip, or B-strip. As used herein, an "I-strip" can refer to a portion of an image composed of macroblocks, all of which are based on macroblocks within the same image. Furthermore, as used herein, in some aspects, "P-strip" and "B-strip" can refer to portions of an image composed of macroblocks that do not depend on macroblocks within the same image.

[0032] In some examples, motion estimation unit 204 can perform unidirectional prediction on the current video block, and can search reference images in list 0 or list 1 to find a reference video block for the current video block. Motion estimation unit 204 can then generate a reference index indicating the reference image containing the reference video block in list 0 or list 1, and a motion vector indicating the spatial displacement between the current video block and the reference video block. Motion estimation unit 204 can output the reference index, prediction direction indicator, and motion vector as motion information for the current video block. Motion compensation unit 205 can generate a predicted video block for the current video block based on the reference video block indicated by the motion information of the current video block.

[0033] Alternatively, in other examples, motion estimation unit 204 can perform bidirectional prediction on the current video block. Motion estimation unit 204 can search for reference images in list 0 to find a reference video block for the current video block, and can also search for reference images in list 1 to find another reference video block for the current video block. Motion estimation unit 204 can then generate reference indices indicating the reference images containing the reference video blocks in lists 0 and 1, and motion vectors indicating the spatial displacement between the reference video blocks and the current video block. Motion estimation unit 204 can output the reference index and motion vector of the current video block as motion information for the current video block. Motion compensation unit 205 can generate a predicted video block for the current video block based on the reference video blocks indicated by the motion information of the current video block.

[0034] In some examples, the motion estimation unit 204 can output a complete set of motion information for use in the decoder's decoding process. Alternatively, in some embodiments, the motion estimation unit 204 can reference the motion information of another video block to transmit the motion information of the current video block via a signal. For example, the motion estimation unit 204 can determine that the motion information of the current video block is sufficiently similar to the motion information of neighboring video blocks.

[0035] In one example, the motion estimation unit 204 may indicate a value to the video decoder 300 in the syntax structure associated with the current video block, which indicates that the current video block has the same motion information as another video block.

[0036] In another example, motion estimation unit 204 may identify another video block and motion vector difference (MVD) in the syntax structure associated with the current video block. The motion vector difference indicates the difference between the motion vector of the current video block and the motion vector of the indicated video block. Video decoder 300 can use the motion vector of the indicated video block and the motion vector difference to determine the motion vector of the current video block.

[0037] As discussed above, the video encoder 200 can transmit motion vectors via signals in a predictive manner. Two examples of predictive signaling techniques that can be implemented by the video encoder 200 include Advanced Motion Vector Prediction (AMVP) and Merge Pattern Signaling.

[0038] Intra-prediction unit 206 can perform intra-prediction on the current video block. When intra-prediction unit 206 performs intra-prediction on the current video block, it can generate prediction data for the current video block based on decoded samples of other video blocks in the same frame. The prediction data for the current video block can include the predicted video block and various syntax elements.

[0039] The residual generation unit 207 can generate residual data for the current video block by subtracting (e.g., indicated by a minus sign) multiple predicted video blocks from the current video block. The residual data for the current video block can include residual video blocks corresponding to different sample components of the samples in the current video block.

[0040] In other examples, such as in skip mode, there may be no residual data for the current video block, and the residual generation unit 207 may not perform subtraction operations.

[0041] The transform processing unit 208 can generate one or more transform coefficient video blocks for the current video block by applying one or more transforms to the residual video blocks associated with the current video block.

[0042] After the transform processing unit 208 generates a transform coefficient video block associated with the current video block, the quantization unit 209 can quantize the transform coefficient video block associated with the current video block based on one or more quantization parameter (QP) values ​​associated with the current video block.

[0043] The inverse quantization unit 210 and the inverse transform unit 211 can apply inverse quantization and inverse transform to the transform coefficient video block respectively to reconstruct the residual video block from the transform coefficient video block. The reconstruction unit 212 can add the reconstructed residual video block to the corresponding samples from one or more predicted video blocks generated by the prediction unit 202 to generate a reconstructed video block associated with the current video block, which is stored in the buffer 213.

[0044] After the video block is reconstructed by reconstruction unit 212, a loop filtering operation can be performed to reduce video block artifacts in the video block.

[0045] Entropy encoding unit 214 can receive data from other functional components of video encoder 200. When entropy encoding unit 214 receives data, it can perform one or more entropy encoding operations to generate entropy-encoded data and output a bitstream including the entropy-encoded data.

[0046] Figure 3 This is a block diagram illustrating an example of a video decoder 300 according to some embodiments of the present disclosure. The video decoder 300 may be... Figure 1 An example of video decoder 124 in system 100 is shown.

[0047] The video decoder 300 can be configured to perform any or all of the technologies disclosed herein. Figure 3 In the example, the video decoder 300 includes multiple functional components. The techniques described in this disclosure can be shared among the various components of the video decoder 300. In some examples, the processor can be configured to perform any or all of the techniques described in this disclosure.

[0048] exist Figure 3 In the example, the video decoder 300 includes an entropy decoding unit 301, a motion compensation unit 302, an intra-frame prediction unit 303, an inverse quantization unit 304, an inverse transform unit 305, a reconstruction unit 306, and a buffer 307. In some examples, the video decoder 300 can perform a decoding process that is generally contrasted with the encoding process described with respect to the video encoder 200.

[0049] Entropy decoding unit 301 can retrieve encoded bitstreams. Encoded bitstreams may include entropy-encoded video data (e.g., encoded video data blocks). Entropy decoding unit 301 can decode the entropy-encoded video data, and motion compensation unit 302 can determine motion information from the entropy-decoded video data, including motion vectors, motion vector precision, reference picture list indices, and other motion information. Motion compensation unit 302 can determine this information, for example, by performing AMVP and Merge pattern. AMVP is used, which involves deriving several most likely candidates based on data from adjacent PBs and reference pictures. Motion information typically includes horizontal and vertical motion vector displacement values, one or two reference picture indices, and, in the case of a prediction region in a B-strip, an identifier of which reference picture list is associated with each index. As used herein, in some aspects, "Merge pattern" can refer to deriving motion information from spatially or temporally adjacent blocks.

[0050] The motion compensation unit 302 can generate motion compensation blocks and can perform interpolation based on an interpolation filter. The identifier of the interpolation filter to be used, with sub-pixel accuracy, can be included in the syntax element.

[0051] The motion compensation unit 302 can use the interpolation filter used by the video encoder 200 during the encoding of the video block to calculate the interpolation for sub-integer pixels of the reference block. The motion compensation unit 302 can determine the interpolation filter used by the video encoder 200 based on the received syntax information, and the motion compensation unit 302 can use the interpolation filter to generate the prediction block.

[0052] Motion compensation unit 302 may use at least some of the syntax information to determine the size of the blocks used to encode (multiple) frames and / or (multiple) stripes of the encoded video sequence, segmentation information describing how each macroblock of the image of the encoded video sequence is segmented, a pattern indicating how each segment is encoded, one or more reference frames (and a list of reference frames) for each inter-frame coded block, and other information for decoding the encoded video sequence. As used herein, in some aspects, a “strip” can refer to a data structure that can be decoded independently of other stripes of the same image in terms of entropy encoding / decoding, signal prediction, and residual signal reconstruction. A strip can be an entire image or a region of an image.

[0053] Intra-prediction unit 303 can use, for example, an intra-prediction mode received in the bitstream to form prediction blocks from spatially adjacent blocks. Dequantization unit 304 dequantizes (i.e., dequantizes) the quantized video block coefficients provided in the bitstream and decoded by entropy decoding unit 301. Inverse transform unit 305 applies the inverse transform.

[0054] The reconstruction unit 306 can obtain the decoded block, for example, by adding the residual block to the corresponding predicted block generated by the motion compensation unit 302 or the intra-frame prediction unit 303. If necessary, a deblocking filter can also be used to filter the decoded block to eliminate block artifacts. The decoded video block is then stored in a buffer 307, which provides a reference block for subsequent motion compensation / intra-frame prediction and also generates decoded video for presentation on a display device.

[0055] Some exemplary embodiments of this disclosure will be described in detail below. It should be understood that section headings are used in this document for ease of understanding and not to limit the embodiments disclosed in a section to that section only. Furthermore, while specific embodiments are described with reference to multi-functional video codecs or other specific video codecs, the disclosed techniques are also applicable to other video codec techniques. Additionally, while some embodiments describe video encoding and decoding steps in detail, it should be understood that the corresponding decoding steps to undo encoding and decoding will be implemented by the decoder. Furthermore, the term "video processing" includes video encoding and decoding or compression, video decoding or decompression, and video transcoding, wherein video pixels are represented from one compression format to another or at different compression bitrates.

[0056] 1. Brief Overview This disclosure relates to video codec technology. Specifically, the technology involves intra-frame template matching prediction and its fusion with other codec tools, as well as other codec tools in image / video codecs. It can be applied to existing video codec standards such as HEVC or VVC. It can also be applied to future video codec standards or video codecs.

[0057] 2. Introduction Video codec standards have primarily evolved through the development of well-known ITU-T and ISO / IEC standards. ITU-T developed the H.261 and H.263 standards, while ISO / IEC developed MPEG-1 and MPEG-4 Vision. These two organizations jointly developed the H.262 / MPEG-2 video standard, the H.264 / MPEG-4 Advanced Video Codec (AVC) standard, and the H.265 / HEVC standard. Starting with H.262, video codec standards are based on a hybrid video codec architecture, which utilizes temporal prediction plus transform coding. To explore future video codec technologies beyond HEVC, VCEG and MPEG jointly established the Joint Video Exploration Team (JVET) in 2015. Since then, JVET has adopted many new methods and incorporated them into reference software called the Joint Exploration Model (JEM). In April 2018, the Joint Video Experts Group (JVET) between ITU-T VCEG (Q6 / 16) and ISO / IEC JTC1 SC29 / WG11 (MPEG) was established to work on the VVC standard, aiming to reduce the bitrate by 50% compared to HEVC. ITU-T VCEG (Q6 / 16) and ISO / IEC MPEG (JTC 1 / SC 29 / WG 5) are investigating the potential need for standardization of future video codec technologies with compression capabilities significantly exceeding the current VVC standard. Such future standardization efforts could take the form of multiple additional extensions to VVC or entirely new standards. These groups are conducting this exploration through a joint collaborative effort called the Joint Video Exploration Team (JVET) to evaluate compression technology designs proposed by experts in the field. New codec features and coding methods implemented in Enhanced Compression Model (ECM) software, as potential enhanced video codec technologies exceeding VVC capabilities, are being coordinated and explored by the Joint Video Exploration Team (JVET) of ITU-T VCEG and ISO / IEC MPEG.

[0058] 2.1. Encoder / decoder streams of typical video codecs Figure 4 An example of a VVC encoder block diagram is shown, comprising three loop filtering blocks: Deblocking Filter (DF), Sample Adaptive Compensation (SAO), and ALF. Unlike DF, which uses predefined filters, SAO and ALF utilize the original samples of the current image, reducing the mean square error between the original and reconstructed samples by adding compensation and by applying a Finite Impulse Response (FIR) filter, respectively, and by utilizing the encoded / decoded side information through signal transmission compensation and filter coefficients. ALF is located in the last processing stage of each image and can be viewed as a tool attempting to capture and repair artifacts caused by previous stages.

[0059] 2.2. Intra-mode encoding and decoding with 67 intra-prediction modes To capture arbitrary edge directions presented in natural video, such as Figure 5 As shown, the number of directional intra-prediction modes has been expanded from 33 used in HEVC to 65, while the planar and DC modes remain unchanged. These denser directional intra-prediction modes are applicable to all block sizes and both luma and chroma intra-prediction.

[0060] In HEVC, each intra-codec block has a square shape, and the length of each side is a power of 2. Therefore, no division is needed to generate intra-prediction values ​​using DC mode. In VVC, blocks can have rectangular shapes, which generally requires division for each block. To avoid division for DC prediction, only the longer side is used to calculate the average of non-square blocks.

[0061] 2.2.1. Wide-angle intra-frame prediction Although 67 modes are defined in VVC, the precise prediction direction for a given intra-prediction mode index depends on the block shape. Regular angular intra-prediction directions are defined clockwise from 45 degrees to -135 degrees. In VVC, for non-square blocks, several regular angular intra-prediction modes are adaptively replaced with wide-angle intra-prediction modes. The replaced modes are transmitted via signaling using the original mode index, which is then remapped to the wide-angle mode index after resolution. The total number of intra-prediction modes remains unchanged at 67, and the intra-mode encoding / decoding method also remains unchanged.

[0062] To support these predicted directions, such as Figure 6 As shown, a top reference with a length of 2W+1 and a left reference with a length of 2H+1 are defined.

[0063] The number of modes replaced in the wide-angle directional mode depends on the aspect ratio of the block. The replaced intra-prediction modes are shown in Table 2-1.

[0064] Table 2-1 – Intra-prediction modes replaced by wide-angle mode

[0065] like Figure 7As shown, in the case of wide-angle intra-frame prediction, two vertically adjacent predicted samples can use two non-adjacent reference samples. Therefore, a low-pass reference sample filter and edge smoothing are applied to wide-angle prediction to reduce the negative impact of the increased gap ∆pα. This is if the wide-angle mode represents a non-fractional offset. There are 8 wide-angle modes that satisfy this condition, namely [-14, -12, -10, -6, 72, 76, 78, 80]. When a block is predicted through these modes, the samples in the reference buffer are directly copied without applying any interpolation. This modification reduces the number of samples that need to be smoothed. Furthermore, it aligns the design of non-fractional modes in regular prediction modes with that of wide-angle modes.

[0066] In VVC, in addition to 4:2:0, 4:2:2 and 4:4:4 chroma formats are also supported. The chroma derivation mode (DM) derivation table for the 4:2:2 chroma format was originally ported from HEVC, with the number of entries expanded from 35 to 67 to align with the expansion of intra-prediction modes. Since the HEVC specification does not support prediction angles below -135 degrees and above 45 degrees, the luma intra-prediction modes ranging from 2 to 5 are mapped to 2. Therefore, the chroma DM derivation table for the 4:2:2 chroma format is updated by replacing some values ​​in the mapping table entries to more accurately translate the prediction angles for chroma blocks.

[0067] 2.3. Inter-frame prediction For each inter-frame prediction CU, motion parameters consist of a motion vector, a reference picture index, and a reference picture list usage index, along with additional information required for inter-frame prediction sample generation using new encoding / decoding features of the VVC. Motion parameters can be transmitted via signaling in an explicit or implicit manner. When a CU is encoded / decoded in skip mode, the CU is associated with a PU and has no significant residual coefficients, no encoded / decoded motion vector increments, or a reference picture index. A Merge mode is defined where motion parameters for the current CU are obtained from neighboring CUs, including spatial and temporal candidates and additional scheduling introduced in the VVC. The Merge mode can be applied to any inter-frame prediction CU, not just skip mode. An alternative to the Merge mode is explicit transmission of motion parameters, where for each CU, the motion vector, the corresponding reference picture index for each reference picture list, the reference picture list usage flag, and other necessary information are explicitly transmitted via signaling.

[0068] 2.4. Intra-Block Copy (IBC) Intra-Block Copy (IBC) is a tool used in the HEVC extension on SCC. It is well known to significantly improve the encoding and decoding efficiency of screen content material. Since IBC mode is implemented as a block-level encoding and decoding mode, block matching (BM) is performed at the encoder to find the optimal block vector (or motion vector) for each CU. Here, the block vector is used to indicate the displacement from the current block to a reference block that has already been reconstructed within the current image. The luma block vector of an IBC-encoded CU is integer precise. The chroma block vector is also rounded to integer precision. When combined with AMVR, IBC mode can switch between 1-pixel motion vector precision and 4-pixel motion vector precision. IBC-encoded CUs are considered a third prediction mode, distinct from intra-frame or inter-frame prediction modes. IBC mode is suitable for CUs with a width and height of 64 luma samples or less.

[0069] On the encoder side, hash-based motion estimation for IBC is performed. The encoder performs RD verification on blocks with a width or height no greater than 16 luminance samples. For non-Merge mode, a block vector search is first performed using a hash-based search. If the hash search does not return valid candidates, a local search based on block matching is performed.

[0070] In hash-based search, hash key matching (32-bit CRC) between the current block and reference blocks is extended to all allowed block sizes. Hash key calculation for each location in the current image is based on 4×4 sub-blocks. For the larger current block, a hash key match with a reference block is determined when all hash keys of all 4×4 sub-blocks match the hash key at the corresponding reference location. If multiple reference blocks are found to match the hash key of the current block, the block vector cost of each matching reference is calculated, and the one with the lowest cost is selected.

[0071] In block matching search, the search range is set to cover both the previous CTU and the current CTU. At the CU level, the IBC mode is transmitted via signaling using a flag, and it can be transmitted via signaling as either IBC AMVP mode or IBC skip / Merge mode as follows: – IBC Skip / Merge Mode: The Merge candidate index is used to indicate which block vector from the list of neighboring candidate IBC codec blocks is used to predict the current block. The Merge list consists of a spatial domain, HMVP, and paired candidates.

[0072] – IBC AMVP Mode: Block vector differences are encoded and decoded in the same way as motion vector differences. The block vector prediction method uses two candidates as prediction values, one from the left neighbor and one from the upper neighbor (if IBC encoded and decoded). When either neighbor is unavailable, the default block vector is used as the prediction value. A flag is transmitted via signaling to indicate the index of the block vector prediction value.

[0073] 2.5. IBC Movement Candidates The term "block" can refer to a codec tree block (CTB), codec tree unit (CTU), codec block (CB), CU, PU, ​​TU, PB, TB, or a video processing unit comprising multiple samples / pixels. Blocks can be rectangular or non-rectangular.

[0074] For IBC-encoded blocks, the block vector (BV) is used to indicate the displacement from the current block to a reference block that has already been reconstructed within the current image. W and H are the width and height of the current block (e.g., the luma block).

[0075] The non-adjacent spatial domain candidates of the current encoding / decoding block are the adjacent spatial domain candidates of the virtual block in the i-th round of search (e.g., Figure 9 (As shown). For the i-th search round, the width and height of the virtual block are calculated using the following formulas: newWidth = i × 2 × gridX + W, newHeight = i × 2 × gridY + H. Clearly, if search round i is 0, then the virtual block is the current block.

[0076] In the following text, BV predictions are also BV candidates. Skip mode is also Merge mode. BV candidates can be divided into several groups according to some criteria. Each group is called a subgroup. For example, we can group adjacent spatial and temporal BV candidates as the first subgroup and the remaining BV candidates as the second subgroup; in another example, we can also group the first N (N≥2) BV candidates as the first subgroup, the next M (M≥2) BV candidates as the second subgroup, and the remaining BV candidates as the third subgroup.

[0077] 2.6. Merge Pattern with MVD (MMVD) In addition to the Merge mode (where implicitly derived motion information is directly used to generate prediction samples for the current CU), a Merge mode with motion vector difference (MMVD) is also introduced in VVC. Immediately after sending the regular Merge flag, the MMVD flag is transmitted via signaling to specify whether the MMVD mode is used for the CU.

[0078] In MMVD, after a Merge candidate is selected, it is further refined using MVD information transmitted via signals. This further information includes a Merge candidate flag, an index specifying the amplitude of motion, and an index indicating the direction of motion. In MMVD mode, one of the top two candidates in the Merge list is selected as the basis for the MV. The MMVD candidate flag is transmitted via signals to specify which candidate to use between the first and second Merge candidates.

[0079] The distance index specifies the motion amplitude information and indicates a predefined offset from the starting point. For example... Figure 8 As shown, the offset is added to the horizontal or vertical component of the starting MV. The relationship between the distance index and the predefined offset is specified in Table 2-2.

[0080] Table 2-2 – Relationship between Distance Index and Predefined Offset

[0081] The direction index indicates the direction of the MVD relative to the starting point. The direction index can represent the four directions shown in Table 2-3. It is important to note that the meaning of the MVD sign can vary depending on the information of the starting MV. When the starting MV is a unidirectional or bidirectional predictive MV (where both lists point to the same side of the current image, i.e., both reference POCs are greater than or less than the current image's POC), the signs in Table 2-3 specify the sign of the MV offset added to the starting MV. When the starting MV is a bidirectional predictive MV (where the two MVs point to different sides of the current image, i.e., one reference POC is greater than the current image's POC, and the other reference POC is less than the current image's POC), and the POC difference in list 0 is greater than the POC difference in list 1, the signs in Table 2-3 specify the sign of the MV offset added to the list0 MV component of the starting MV, and the signs for list1 MV have the opposite value. Otherwise, if the POC difference in list 1 is greater than the POC difference in list 0, the signs in Table 2-3 specify the signs of the MV offsets added to the list 1 MV component of the starting MV, and have the opposite values ​​for the signs of the list 0 MV.

[0082] MVD is scaled based on the difference in POC in each direction. If the difference in POC in the two lists is the same, no scaling is needed. Otherwise, if the difference in POC in list 0 is greater than the difference in POC in list 1, then the MVD of list 1 is scaled by defining the difference in POC in L0 as td and the difference in POC in L1 as tb, as follows. Figure 26As shown. If the POC difference of L1 is greater than the POC difference of L0, then the MVD of list 0 is scaled in the same way. If the initial MV is predicted unidirectionally, then the MVD is added to the available MV.

[0083] Table 2-3 – Signs of MV Offsets Defined by Direction Index

[0084] 2.7. Symmetric MVD Encoding and Decoding In VVC, in addition to the normal one-way and two-way prediction MVD signal transmission, a symmetrical MVD mode for two-way prediction MVD signal transmission is also applied. In the symmetrical MVD mode, the reference image indices of both List 0 and List 1, as well as the motion information of the MVD in List 1, are not transmitted via signal transmission but are derived.

[0085] The decoding process of the symmetric MVD mode is as follows: 1) At the strip level, the variables BiDirPredFlag, RefIdxSymL0, and RefIdxSymL1 are derived as follows: – If mvd_l1_zero_flag is 1, then BiDirPredFlag is set to 0.

[0086] Otherwise, if the most recent reference image in list 0 and the most recent reference image in list 1 form a forward and reverse reference image pair or a reverse and forward reference image pair, then BiDirPredFlag is set to 1, and both the reference images in list 0 and list 1 are short-term reference images. Otherwise, BiDirPredFlag is set to 0.

[0087] 2) At the CU level, if the CU is bidirectional predictive codec and BiDirPredFlag is equal to 1, then the symmetric mode flag indicating whether to use symmetric mode is explicitly indicated by signal transmission.

[0088] When the symmetric mode flag is true, only mvp_l0_flag, mvp_l1_flag, and MVD0 are explicitly transmitted via signals. The reference indices of list 0 and list 1 are set to [values ​​to be inserted here].

[0089] In the encoder, symmetric MVD motion estimation begins with an initial MV evaluation. A set of initial MV candidates includes MVs obtained from a one-way prediction search, MVs obtained from a two-way prediction search, and MVs from an AMVP list. The one with the lowest rate-distortion cost is selected as the initial MV for the symmetric MVD motion search.

[0090] 2.8. Bidirectional Optical Flow (BDOF) The Bidirectional Optical Flow (BDOF) tool is included in VVC. BDOF, formerly known as BIO, was included in JEM. Compared to the JEM version, the BDOF in VVC is a simpler version, requiring significantly less computation, especially in terms of the number of multiplications and multiplier size.

[0091] BDOF is used to refine the bidirectional prediction signal of the CU at the 4×4 sub-block level. BDOF is applied to the CU if all of the following conditions are met: – CU is encoded and decoded using a “true” bidirectional prediction mode, that is, one of the two reference images is displayed before the current image in the order of display, and the other is displayed after the current image in the order of display; – The distances (i.e., the difference in point of view) from the two reference images to the current image are the same; – Both reference images are short-term reference images; – CU is not encoded or decoded using affine mode or SbTMVP Merge mode; – The CU has more than 64 luminance samples; – Both the CU height and CU width are greater than or equal to 8 luminance samples; – The BCW weight index indicates equal weights; – WP is not enabled for the current CU; – CIIP mode is not used in the current CU.

[0092] BDOF is applied only to the luminance component. As the name suggests, the BDOF mode is based on the concept of optical flow, which assumes that the motion of the object is smooth. For each 4×4 sub-block, motion refinement is calculated by minimizing the difference between the L0 predicted samples and the L1 predicted samples. Motion refinement is then used to adjust the bidirectional prediction sample values ​​in the 4×4 sub-blocks. The following steps are applied during the BDOF process.

[0093] First, the horizontal and vertical gradients of the two predicted signals. and , It is calculated by directly calculating the difference between two neighboring sample points, that is,

[0094] in It is a list Coordinates of the predicted signal in The sample value at the location, and shift1 is calculated based on the luminance bit depth bitDepth as shift1 = max(6, bitDepth-6).

[0095] Then, the autocorrelation and cross-correlation of the gradients. Calculated as

[0096] in

[0097] in It is a 6x6 window surrounding a 4x4 sub-block, and and The values ​​are set to min(1, bitDepth – 11) and min(4, bitDepth – 8) respectively.

[0098] Then, use the following formula to refine the motion. It is derived using cross-correlation and autocorrelation terms:

[0099] in . It is a floor function, and .

[0100] Based on motion refinement and gradients, the following adjustments are calculated for each sample point in the 4×4 sub-block:

[0101] Finally, the BDOF samples of CU are calculated by adjusting the bidirectional prediction samples as follows:

[0102] These values ​​are chosen so that the multiplier in the BDOF process does not exceed 15 bits, and the maximum bit width of the intermediate parameters in the BDOF process is kept within 32 bits.

[0103] To derive the gradient values, a list of values ​​outside the current CU boundary needs to be generated. Some predicted samples .like Figure 10 As shown, BDOF in VVC uses an extended row / column around the CU boundary. To control the computational complexity of generating prediction samples outside the boundary, prediction samples in the extended region (white area) are generated by directly taking reference samples at nearby integer positions (using the floor() operation on coordinates) without interpolation, and a normal 8-tap motion-compensated interpolation filter is used to generate prediction samples inside the CU (gray area). These extended sample values ​​are used only for gradient calculation. For the remaining steps in the BDOF process, if any samples and gradient values ​​outside the CU boundary are needed, they are filled from their nearest neighbors (i.e., repeated).

[0104] When the width and / or height of a CU is greater than 16 luminance samples, it will be divided into sub-blocks with a width and / or height equal to 16 luminance samples, and the sub-block boundaries will be considered as CU boundaries in the BDOF process. The maximum cell size for the BDOF process is limited to 16×16. The BDOF process can be skipped for each sub-block. The BDOF process is not applied to the sub-block when the SAD between the initial L0 predicted samples and the L1 predicted samples is less than a threshold. The threshold is set to equal to (8... W (H>>1), where W indicates the sub-block width and H indicates the sub-block height. To avoid the additional complexity of SAD calculation, the SAD between the initial L0 prediction samples and L1 prediction samples calculated during the DVMR process is reused here.

[0105] Bidirectional optical flow (BDOF) is disabled if BCW is enabled for the current block, meaning the BCW weight index indicates unequal weights. Similarly, BDOF is disabled if WP is enabled for the current block, meaning luma_weight_lx_flag is 1 for either of the two reference images. BDOF is also disabled when the CU is encoded / decoded using symmetric MVD mode or CIIP mode.

[0106] 2.9. Inter-frame and Intra-frame Joint Prediction (CIIP) 2.10. Affine Motion Compensation Prediction In HEVC, only the translational motion model is applied to motion compensation prediction (MCP). In the real world, there are many types of motion, such as zooming in / out, rotation, perspective motion, and other irregular motions. In VVC, block-based affine transformation motion compensation prediction is applied. Figure 11 As shown, the affine motion field of a block is described by motion information from two control points (4 parameters) or three control point motion vectors (6 parameters).

[0107] For the 4-parameter affine motion model, the motion vector at the sample point position (x, y) in the block is derived as follows:

[0108] For the 6-parameter affine motion model, the motion vector at the sample point position (x, y) in the block is derived as follows:

[0109] Where (mv0x, mv0y) is the motion vector of the top left control point, (mv1x, mv1y) is the motion vector of the top right control point, and (mv2x, mv2y) is the motion vector of the bottom left control point.

[0110] To simplify motion compensation prediction, block-based affine transformation prediction is applied. To derive the motion vector for each 4×4 lumen sub-block, the motion vector of the center sample point of each sub-block is calculated according to the above equation (e.g., ...). Figure 12 (As shown), and rounded to 1 / 16 fractional precision. Then a motion-compensated interpolation filter is applied to generate a prediction for each sub-block with a derived motion vector. The sub-block size for the chroma component is also set to 4×4. The MV of the 4×4 chroma sub-block is calculated as the average of the MVs of the four corresponding 4×4 luma sub-blocks.

[0111] Similar to translational motion inter-frame prediction, there are two affine motion inter-frame prediction modes: affine Merge mode and affine AMVP mode.

[0112] 2.10.1. Affine Merge Prediction The AF_MERGE mode can be applied to CUs with a width and height greater than or equal to 8. In this mode, the CPVM of the current CU is generated based on the motion information of spatially neighboring CUs. There can be up to five CPVM candidates, and the one to be used for the current CU is indicated by a signal transmission index. The following three types of CPVM candidates are used to form the affine merge candidate list: – Inherited affine Merge candidates inferred from the CPMV of neighboring CUs; – Affine Merge candidate CPMVP constructed using translational MV derivation of neighboring CUs; – Zero MV.

[0113] In VVC, there are at most two inherited affine candidates, which are derived from the affine motion model of neighboring blocks: one from the left neighboring CU and one from the upper neighboring CU. Candidate blocks are as follows: Figure 13 As shown. For the left-side prediction, the scan order is A0->A1, and for the top-side prediction, the scan order is B0->B1->B2. Only the first inherited candidate from each side is selected. No deduplication check is performed between candidates from two inheritances. When a neighboring affine CU is identified, its control point motion vector is used to derive the CPMVP candidate in the affine Merge list of the current CU. As shown, if the neighboring lower-left block A is encoded and decoded in affine mode, the motion vectors of the upper-left, upper-right, and lower-left corners of the CU containing block A are obtained. When block A is encoded and decoded using a 4-parameter affine model, the two CPMVs of the current CU are based on... Computed. When block A is encoded and decoded using a 6-parameter affine model, the three CPMVs of the current CU are calculated according to... Calculated.

[0114] The constructed affine candidate means that the candidate is constructed by combining the translational motion information of the neighbors of each control point. The motion information of the control points is derived from... Figure 15 The spatial and temporal nearest neighbors shown are derived. CPMV k (k=1, 2, 3, 4) represents the k-th control point. For CPMV1, check the B2->B3->A2 block and use the MV of the first available block. For CPMV2, check the B1->B0 block, and for CPMV3, check the A1->A0 block. If available, the TMVP is used as CPMV4.

[0115] After obtaining the motion signatures (MVs) of the four control points, the affine Merge candidate is constructed based on this motion information. The following combinations of control point MVs are used for sequential construction: {CPMV1, CPMV2, CPMV3}, {CPMV1, CPMV2, CPMV4}, {CPMV1, CPMV3, CPMV4}, {CPMV2, CPMV3, CPMV4}, { CPMV1, CPMV2}, { CPMV1, CPMV3}.

[0116] Combining three CPMVs constructs a 6-parameter affine merge candidate, and combining two CPMVs constructs a 4-parameter affine merge candidate. To avoid motion scaling, combinations of control point MVs are discarded if the reference indices of the control points are different.

[0117] After the inherited affine Merge candidates and the constructed affine Merge candidates are checked, if the list is still not full, a zero MV is inserted at the end of the list.

[0118] 2.10.2. Affine AMVP Prediction The affine AMVP mode can be applied to CUs with a width and height both greater than or equal to 16. An affine flag at the CU level is signaled in the bitstream to indicate whether the affine AMVP mode is used, and another flag is signaled to indicate whether it is a 4-parameter affine or a 6-parameter affine. In this mode, the difference between the current CU's CPVM and its predicted CPMVP is signaled in the bitstream. The affine AMVP candidate list is of size 2 and is generated by sequentially using the following four types of CPVM candidates: – Inherited affine AMVP candidates inferred from the CPMV of neighboring CUs; – A constructive affine AMVP candidate CPMVP derived using translational MV of neighboring CUs; – Translation MV from the neighboring CU; – Zero MV.

[0119] The checking order for inherited affine AMVP candidates is the same as that for inherited affine Merge candidates. The only difference is that, for AVMP candidates, only affine CUs with the same reference picture as those in the current block are considered. No deduplication process is applied when inserting inherited affine motion predictions into the candidate list.

[0120] The constructed AMVP candidate is from Figure 15 The specified spatial nearest neighbor derivation is shown. The same checking order as in the affine Merge candidate construction is used. Additionally, the reference picture index of neighboring blocks is checked. The block that is the first to be inter-coded in the checking order and has the same reference picture as in the current CU is used. Only one is considered. When the current CU is encoded in a 4-parameter affine mode and both mv0 and mv1 are available, they are added as candidates in the affine AMVP list. When the current CU is encoded in a 6-parameter affine mode and all three CPMVs are available, they are added as candidates in the affine AMVP list. Otherwise, the constructed AMVP candidates are set to unavailable.

[0121] If the affine AMVP list still has fewer than 2 candidates after checking the inherited and constructed AMVP candidates, then mv0, mv1, and mv2 will be added sequentially as translation MVs to predict all control point MVs of the current CU, when available. Finally, if the affine AMVP list is still not full, zero MVs are used to populate the affine AMVP list.

[0122] 2.10.3. Affine Motion Information Storage In VVC, the CPMV of an affine CU is stored in a separate cache. The stored CPMV is used only to generate inherited CPMVPs in the affine Merge mode and affine AMVP mode for the most recently encoded / decoded CU. Subblock MVs derived from the CPMV are used for motion compensation, MV derivation of the Merge / AMVP list for translation MVs, and deblocking.

[0123] To avoid image row caching for additional CPMVs, affine motion data inheritance from the CU of the upper CTU is handled differently from inheritance from regular neighboring CUs. If the candidate CU for affine motion data inheritance is in the upper CTU row, the lower left and lower right sub-block MVs in the row cache, instead of the CPMV, are used for affine MVP derivation. Thus, the CPMV is only stored in the local cache. If the candidate CU is a 6-parameter affine codec, the affine model is downgraded to a 4-parameter model. Figure 16 As shown, along the top CTU boundary, the motion vectors of the lower left and lower right sub-blocks of the CU are used for the affine inheritance of the CU in the bottom CTU.

[0124] 2.10.4. Refinement of Optical Flow Prediction for Affine Modes Compared to pixel-based motion compensation, sub-block-based affine motion compensation can save memory access bandwidth and reduce computational complexity, but at the cost of prediction accuracy. To achieve finer-grained motion compensation, prediction refinement using optical flow (PROF) is used to refine the sub-block-based affine motion compensation prediction without increasing the memory access bandwidth used for motion compensation. In VVC, after sub-block-based affine motion compensation is performed, the brightness prediction samples are refined by adding the difference derived from the optical flow equation. PROF is described in the following four steps: Step 1) Sub-block-based affine motion compensation is performed to generate sub-block predictions. .

[0125] Step 2) Calculate the spatial gradient of the sub-block prediction at each sample location using a 3-tap filter [-1, 0, 1]. and The gradient calculation is exactly the same as the gradient calculation in BDOF.

[0126]

[0127] This is used to control the precision of the gradient. The sub-block (i.e., 4×4) prediction is expanded by one sample point on each side for gradient calculation. To avoid additional memory bandwidth and additional interpolation calculations, those expanded samples on the expanded boundaries are copied from the nearest integer pixel position in the reference image.

[0128] Step 3) Brightness prediction refinement is calculated using the following optical flow equation.

[0129]

[0130] in It refers to the location of the sample points. The calculated sample MV (by (representation) and sample points The difference between the MVs of the sub-blocks of the same sub-block, such as Figure 17 As shown. It is quantized in units of 1 / 32 brightness sample precision.

[0131] Since the affine model parameters and the sample point positions relative to the sub-block center do not change from one sub-block to another, therefore It can be computed for the first sub-block and reused for other sub-blocks in the same CU. This allows... and From the sample point location To the center of the sub-block Horizontal and vertical offsets It can be derived from the following equation:

[0132] To maintain accuracy, the center of the sub-block Calculated as ((W) SB - 1) / 2, (H SB - 1) / 2), where W SB and H SB These are the width and height of the sub-block, respectively.

[0133] For a 4-parameter affine model

[0134] For a 6-parameter affine model

[0135] in These are the motion vectors of the control points at the top left, top right, and bottom left. and These are the width and height of the CU.

[0136] Step 4) Finally, refine the brightness A-level prediction. Added to sub-block prediction The final prediction I' is generated as the following equation.

[0137]

[0138] PROF is not applied to CUs that are affinely encoded or decoded in two cases: 1) All control points MV are the same, which indicates that the CU has only translational motion; 2) The affine motion parameters are greater than the specified limits, because the sub-block-based affine MC is downgraded to the CU-based MC to avoid large memory access bandwidth requirements.

[0139] Fast coding methods are applied to reduce the coding complexity of affine motion estimation using PROF. PROF is not applied in the affine motion estimation stage in the following two cases: a) if the CU is not the root block and its parent block does not choose an affine mode as its optimal mode, then PROF is not applied because the probability of the current CU choosing an affine mode as its optimal mode is low; b) if the magnitudes of all four affine parameters (C, D, E, F) are less than a predefined threshold, and the current image is not a low-latency image, then PROF is not applied because the improvement introduced by PROF is small in this case. Thus, affine motion estimation using PROF can be accelerated.

[0140] 2.11. Sub-block-based temporal motion vector prediction (SbTMVP) VVC supports a sub-block-based temporal motion vector prediction (SbTMVP) method. Similar to temporal motion vector prediction (TMVP) in HEVC, SbTMVP uses the motion field in the co-located image to improve motion vector prediction and merge patterns for the current CU (Cubic Component) in the current image. The same co-located image used by TMVP is used for SbTVMP. SbTMVP differs from TMVP in the following two main aspects: – TMVP predicts motion at the CU level, but SbTMVP predicts motion at the sub-CU level; – TMVP obtains temporal motion vectors from co-op blocks in the co-op image (the co-op block is the lower right or center block relative to the current CU), and SbTMVP applies motion shift before obtaining temporal motion information from the co-op image, where the motion shift is obtained from the motion vector of one of the spatial neighboring blocks from the current CU.

[0141] The SbTVMP process is as follows: Figure 18A and Figure 18B As shown. SbTMVP predicts the motion vectors of sub-CUs within the current CU in two steps. In the first step, it checks... Figure 18A The spatial nearest neighbor A1 in the image is selected. If A1 has a motion vector that uses a co-located image as its reference image, then that motion vector is chosen as the motion shift to apply. If no such motion is identified, the motion shift is set to (0, 0).

[0142] In the second step, the motion shift identified in step 1 is applied (i.e., added to the coordinates of the current block) to shift from, for example... Figure 18B The corresponding image shown obtains motion information (motion vectors and reference indices) at the sub-CU level. Figure 18B The example assumes that motion shift is set as the motion of block A1. Then, for each sub-CU, the motion information of its corresponding block (the smallest motion grid covering the center sample) in the co-location image is used to derive the motion information for the sub-CU. After the motion information of the co-location sub-CU is identified, it is converted into the motion vector and reference index of the current sub-CU in a manner similar to the TMVP process of HEVC, where temporal motion scaling is applied to align the reference image of the temporal motion vector with the reference image of the current CU.

[0143] In VVC, a sub-block-based Merge list containing both SbTVMP candidates and affine Merge candidates is used for signal transmission in sub-block-based Merge mode. The SbTVMP mode is enabled / disabled via the Sequence Parameter Set (SPS) flag. If the SbTVMP mode is enabled, the SbTVMP prediction is added as the first entry in the sub-block-based Merge candidate list, followed by the affine Merge candidate. The size of the sub-block-based Merge list is transmitted via signal transmission in the SPS, and the maximum allowed size of the sub-block-based Merge list in VVC is 5.

[0144] The sub-CU size used in SbTMVP is fixed at 8×8, and like the affine Merge pattern, the SbTMVP pattern only applies to CUs with a width and height greater than or equal to 8.

[0145] The encoding logic for the additional SbTMVP Merge candidate is the same as that for other Merge candidates, that is, for each CU in the P-strip or B-strip, an additional RD check is performed to determine whether to use the SbTMVP candidate.

[0146] 2.12. Adaptive Motion Vector Resolution (AMVR) In HEVC, when `use_integer_mv_flag` in the strip header is equal to 0, the motion vector difference (MVD) (between the CU's motion vector and the predicted motion vector) is transmitted through the signal in units of quarter-luminance samples. In VVC, a CU-level adaptive motion vector resolution (AMVR) scheme is introduced. AMVR allows the CU's MVD to be encoded and decoded with different precisions. Depending on the current CU's mode (normal AMVP mode or affine AVMP mode), the current CU's MVD can be adaptively selected as follows: – Normal AMVP mode: quarter brightness sample, half brightness sample, integer brightness sample or four brightness sample.

[0147] – Affine AMVP mode: quarter luminance sample, integer luminance sample, or 1 / 16 luminance sample.

[0148] If the current CU has at least one non-zero MVD component, the CU-level MVD resolution indication is conditionally transmitted via signal transmission. If all MVD components (i.e., both the horizontal and vertical MVD for reference lists L0 and L1) are zero, the quarter-spot luminance sample MVD resolution is presumed.

[0149] For a CU with at least one non-zero MVD component, a first flag is transmitted to indicate whether quarter-luminance sample MVD precision is used for the CU. If the first flag is 0, no further signal transmission is required, and quarter-luminance sample MVD precision is used for the current CU. Otherwise, a second flag is transmitted to indicate that half-luminance sample or other MVD precision (integer or quad-luminance sample) is used for the normal AMVP CU. In the case of half-luminance sample, a 6-tap interpolation filter is used instead of the default 8-tap interpolation filter for the half-luminance sample position. Otherwise, a third flag is transmitted to indicate whether integer luminance sample MVD precision or quad-luminance sample MVD precision is used for the normal AMVP CU. In the case of an affine AMVP CU, the second flag is used to indicate whether integer luminance sample MVD precision or 1 / 16 luminance sample MVD precision is used. To ensure that the reconstructed MV has the expected precision (quarter-luminance sample, half-luminance sample, integer luminance sample, or quad-luminance sample), the CU's motion vector prediction value is rounded to the same precision as the MVD before being added to the MVD. The motion vector predictions are rounded to zero (i.e., negative motion vector predictions are rounded to positive infinity, and positive motion vector predictions are rounded to negative infinity).

[0150] The encoder uses RD checks to determine the motion vector resolution for the current CU. To avoid always performing four CU-level RD checks for each MVD resolution, in VTM11, RD checks for MVD accuracy other than quarter-luminance samples are only invoked under certain conditions. For normal AVMP mode, the RD costs for quarter-luminance sample MVD accuracy and integer luminance sample MVD accuracy are first calculated. Then, the RD costs for integer luminance sample MVD accuracy are compared with those for quarter-luminance sample MVD accuracy to determine if it is necessary to further check the RD costs for four-luminance sample MVD accuracy. When the RD cost for quarter-luminance sample MVD accuracy is significantly less than the RD cost for integer luminance sample MVD accuracy, the RD check for four-luminance sample MVD accuracy is skipped. Then, if the RD cost for integer luminance sample MVD accuracy is significantly greater than the best RD cost of the previously tested MVD accuracy, the check for half-luminance sample MVD accuracy is skipped. For affine AMVP mode, if the affine inter-frame mode is not selected after checking the rate-distortion cost of affine Merge / Skip mode, Merge / Skip mode, quarter-lumen sample MVD precision normal AMVP mode, and quarter-lumen sample MVD precision affine AMVP mode, then the 1 / 16-lumen sample MVD precision and 1-pixel MVD precision affine inter-frame modes are not checked. Furthermore, in the 1 / 16-lumen sample and quarter-lumen sample MVD precision affine inter-frame modes, the affine parameters obtained in the quarter-lumen sample MVD precision affine inter-frame mode are used as the starting search point.

[0151] 2.13. Bidirectional prediction (BCW) with CU-level weights In HEVC, the bidirectional prediction signal is generated by averaging two prediction signals obtained from two different reference images and / or using two different motion vectors. In VVC, the bidirectional prediction mode extends beyond simple averaging to allow for a weighted average of the two prediction signals.

[0152]

[0153] Five weights are allowed in weighted average two-way forecasting. For each bidirectional prediction CU, the weights w are determined in one of two ways: 1) for non-merge CUs, the weight index is transmitted via signal after the motion vector difference; 2) for merge CUs, the weight index is inferred from neighboring blocks based on the merge candidate index. BCW is applied only to CUs with 256 or more luma samples (i.e., CU width multiplied by CU height is greater than or equal to 256). For low-latency images, all 5 weights are used. For non-low-latency images, only 3 weights are used (w∈{3,4,5}).

[0154] – At the encoder, fast search algorithms are applied to find the weight indices without significantly increasing encoder complexity. These algorithms are summarized below. For more details, refer to the VTM software. When combined with AMVR, if the current image is a low-latency image, unequal weights are conditionally checked for 1-pixel and 4-pixel motion vector precision.

[0155] – When combined with an affine pattern, an affine ME will be performed for unequal weights if and only if the affine pattern is selected as the current best pattern.

[0156] – When the two reference images in bidirectional prediction are the same, conditionally check for unequal weights.

[0157] – Based on the POC distance between the current image and its reference image, the encoding / decoding QP, and the temporal level, unequal weights are not searched when certain conditions are met.

[0158] The BCW weight index uses a context codec bit followed by a bypass codec bit. The first context codec bit indicates whether equal weights are used; if unequal weights are used, additional bits are transmitted via bypass codec to indicate which unequal weights are applied. Weighted Prediction (WP) is a codec tool supported by the H.264 / AVC and HEVC standards for efficiently encoding and decoding video content with fade-in and fade-out. Support for WP has also been added to the VVC standard. WP allows weighting parameters (weights and offsets) to be transmitted via signal for each reference picture in each of the reference picture lists L0 and L1. Then, during motion compensation, the corresponding weights and offsets for the reference picture(s) are applied. WP and BCW are designed for different types of video content. To avoid interaction between WP and BCW, which would complicate the VVC decoder design, if the CU uses WP, the BCW weight index is not transmitted via signal, and w is presumed to be 4 (i.e., equal weights are applied). For Merge CUs, the weight index is inferred from neighboring blocks based on the Merge candidate index. This can be applied to both normal Merge patterns and inherited affine Merge patterns. For constructed affine Merge patterns, affine motion information is constructed based on the motion information of up to 3 blocks. The BCW index of a CU using a constructed affine Merge pattern is simply set to be equal to the BCW index of the first control point MV.

[0159] In VVC, CIIP and BCW cannot be jointly applied to a CU. When a CU is encoded or decoded using CIIP mode, the BCW index of the current CU is set to 2, for example, with equal weights.

[0160] 2.14. Local Illumination Compensation (LIC) Local Illumination Compensation (LIC) is an encoding / decoding tool used to address the problem of local illumination variations between the current image and its temporal reference image. LIC is based on a linear model, where a scaling factor and offset are applied to the reference samples to obtain the predicted samples for the current block. Specifically, LIC can be mathematically modeled using the following equation:

[0161] in Is the current block at coordinates Predicted signal at the location; It is composed of motion vectors The reference block it points to; These are the corresponding scaling factors and offsets applied to the reference block. Figure 19 The LIC procedure is shown. Figure 19 In this context, when applying LIC to a block, the Minimum Mean Square Error (LMSE) method is employed to minimize the number of neighboring samples in the current block (i.e., Figure 19 The template T in the image and its corresponding reference sample in the time-domain reference image (i.e., Figure 19 The LIC parameter is derived from the difference between T0 or T1 in the original text. The value of ). Furthermore, to reduce computational complexity, both the template samples and the reference template samples are downsampled (adaptive downsampling) to derive the LIC parameters; that is, only Figure 19 The shaded samples in the data were used for derivation. .

[0162] To improve encoding and decoding performance, such as Figure 20 As shown, downsampling is not performed on the shorter side.

[0163] 2.15. Decoder-side Motion Vector Refinement (DMVR) To improve the accuracy of motion vector refinement (MV) in Merge mode, decoder-side refinement based on bilateral matching (BM) is applied in VVC. In the bidirectional prediction operation, a refined MV is searched around the initial MV in reference image lists L0 and L1. The BM method computes the distortion between two candidate blocks in reference image lists L0 and L1. Figure 21 As shown, the SAD between two blocks of each MV candidate (e.g., MV0' and MV1') around the initial MV is calculated. The MV candidate with the lowest SAD becomes the refined MV and is used to generate the bidirectional prediction signal.

[0164] In VVC, the application of DMVR is restricted and can only be used with CUs encoded and decoded using the following modes and features: – CU-level Merge pattern with bidirectional prediction MV – Relative to the current image, one reference image is from the past and the other is from the future. – The distances (i.e., the difference in point of view) from the two reference images to the current image are the same. – Both reference images are short-term reference images. – The CU has more than 64 luminance samples. – Both the CU height and CU width are greater than or equal to 8 luminance samples. – The BCW weight index indicates equal weights. – Do not enable WP for the current block – CIIP mode is not used in the current block.

[0165] The refined motion vector (MV) derived through the DMVR process was used to generate inter-frame prediction samples and also for temporal motion vector prediction in future image encoding and decoding. The original MV was used in the deblocking process and also for spatial motion vector prediction in future CU encoding and decoding.

[0166] Additional features of DMVR are mentioned in the following sub-entries.

[0167] 2.15.1. Search Scheme In DVMR, the search point revolves around the initial MV, and the MV offset follows the MV difference mirror rule. In other words, any point examined by DMVR, represented by the candidate MV pair (MV0, MV1), obeys the following two equations:

[0168] in This represents the refinement offset between the initial MV and the refined MV in one of the reference images. The refinement search range is two integer luminance samples from the initial MV. The search includes an integer sample offset search phase and a fractional sample refinement phase.

[0169] A 25-point full search is applied to the integer sample offset search. First, the SAD of the initial MV pair is calculated. If the SAD of the initial MV pair is less than a threshold, the integer sample stage of DMVR is terminated. Otherwise, the SAD of the remaining 24 points is calculated and checked in raster scan order. The point with the minimum SAD is selected as the output of the integer sample offset search stage. To reduce the impact of DMVR refinement uncertainties, a bias towards the original MV is proposed during the DMVR process. The SAD value between the reference blocks of the initial MV candidate references is reduced by 1 / 4.

[0170] The integer sample search is followed by fractional sample refinement. To save computational complexity, fractional sample refinement is derived using the surface equation of parameter error, rather than through an additional search with SAD comparison. Fractional sample refinement is conditionally invoked based on the output of the integer sample search phase. Fractional sample refinement is further applied when the integer sample search phase terminates in the first or second iteration with the minimum SAD at the center.

[0171] In subpixel offset estimation based on parametric error surfaces, the cost at the center location and the costs at four neighboring locations from the center are used to fit a two-dimensional parabolic error surface equation of the following form.

[0172] in This corresponds to the score position with the minimum cost, and C corresponds to the minimum cost value. The above equation is solved by using the cost values ​​of the five search points. Calculated as:

[0173]

[0174] The value is automatically constrained between -8 and 8 because all values ​​are positive, and the minimum value is... This corresponds to a half-pixel offset with 1 / 16 pixel MV precision. The calculated score... It is added to the integer distance thinning MV to obtain the subpixel accurate thinning increment MV.

[0175] 2.15.2. Bilinear Interpolation and Sample Filling In VVC, the resolution of the MV is 1 / 16 of a lumen sample. Samples at fractional positions are interpolated using an 8-tap interpolation filter. In DMVR, the search point surrounds the initial fractional pixel MV with an integer sample offset; therefore, for the DMVR search process, samples at those fractional positions need to be interpolated. To reduce computational complexity, a bilinear interpolation filter is used to generate fractional samples for the search process in DMVR. Another important effect of using a bilinear filter is that, utilizing a 2-sample search range, DVMR does not access more reference samples compared to the normal motion compensation process. After obtaining the refined MV through the DMVR search process, a normal 8-tap interpolation filter is applied to generate the final prediction. To avoid accessing more reference samples than the normal MC process, samples that are not needed by the interpolation process based on the original MV but are needed by the interpolation process based on the refined MV are filled from these available samples.

[0176] 2.15.3. Maximum DMVR Processing Unit When the width and / or height of a CU is greater than 16 luminance samples, it will be further divided into sub-blocks with a width and / or height equal to 16 luminance samples. The maximum cell size for the DMVR search process is limited to 16×16.

[0177] 2.16. Multi-pass decoder-side motion vector refinement In this contribution, multi-pass decoder-side motion vector refinement is applied instead of DMVR. In the first pass, bilateral matching (BM) is applied to the codec block. In the second pass, BM is applied to each 16×16 sub-block within the codec block. In the third pass, the motion vectors (MVs) in each 8×8 sub-block are refined by applying bidirectional optical flow (BDOF). The refined MVs are stored for both spatial and temporal motion vector prediction.

[0178] 2.16.1. First pass – Block-based bilateral matching MV refinement In the first pass, the refined MV is derived by applying the BM to the codec block. Similar to decoder-side motion vector refinement (DMVR), the refined MV is searched around the two initial MVs (MV0 and MV1) in the reference picture lists L0 and L1. The refined MVs (MV0_pass1 and MV1_pass1) are derived around the initial MVs based on the minimum bilateral matching cost between the two reference blocks in L0 and L1.

[0179] BM performs a local search to derive the integer sample precision intDeltaMV and the half-pixel sample precision halfDeltaMv. The local search applies a 3×3 square search pattern to iterate through the search range [-sHor, sHor] in the horizontal direction and [-sVer, sVer] in the vertical direction, where the values ​​of sHor and sVer are determined by the block dimension, and the maximum value of sHor and sVer is 8.

[0180] The cost of bilateral matching is calculated as: bilCost = mvDistanceCost + sadCost. When the block size is cbW... When cbH is greater than 64, the MRSAD cost function is applied to remove the DC effect of distortion between reference blocks. The local search of intDeltaMV or halfDeltaMV is terminated when bilCost at the center point of the 3×3 search pattern has the minimum cost. Otherwise, the current minimum cost search point becomes the new center point of the 3×3 search pattern, and the search for the minimum cost continues until it reaches the end of the search range.

[0181] The existing fractional sample refinement is further applied to derive the final deltaMV. Then, the refined MV after the first pass is derived as follows: MV0_pass1 = MV0 + deltaMV MV1_pass1 = MV1 – deltaMV.

[0182] 2.16.2. Second pass – Sub-block-based bilateral matching MV refinement In the second pass, the refined MV is derived by applying the BM to 16×16 grid sub-blocks. For each sub-block, the refined MV is searched around the two MVs (MV0_pass1 and MV1_pass1) obtained from the first pass for the reference image lists L0 and L1. The refined MVs (MV0_pass2(sbIdx2) and MV1_pass2(sbIdx2)) are derived based on the minimum bilateral matching cost between the two reference sub-blocks in L0 and L1.

[0183] For each sub-block, BM performs a full search to derive the integer sample precision intDeltaMV. The full search has a search range of [-sHor, sHor] in the horizontal direction and [-sVer, sVer] in the vertical direction, where the values ​​of sHor and sVer are determined by the block dimension, and the maximum value of sHor and sVer is 8.

[0184] The bilateral matching cost is calculated by applying a cost factor to the SATD cost between the two reference subblocks, as follows: bilCost = satdCost costFactor. Search area (2) sHor+1) (2) sVer+1) is classified as Figure 22 A maximum of five diamond-shaped search regions are shown. Each search region is assigned a costFactor, which is determined by the distance (intDeltaMV) between each search point and the starting MV, and each diamond region is processed sequentially starting from the center of the search region. Within each region, search points are processed in raster scan order, starting from the top left corner and ending at the bottom right corner. A minimum bilCost is calculated when the minimum bilCost within the current search region is less than a threshold (which is equal to sbW). When sbH), the integer pixel full search is terminated; otherwise, the integer pixel full search continues to the next search area until all search points have been checked.

[0185] BM performs a local search to derive the half-sample precision halfDeltaMv. The search pattern and cost function are the same as defined in 2.9.1.

[0186] The existing VVC DMVR fractional sample refinement is further applied to derive the final deltaMV(sbIdx2). Then, the refined MV at the second pass is derived as follows: MV0_pass2(sbIdx2) = MV0_pass1 + deltaMV(sbIdx2) MV1_pass2(sbIdx2) = MV1_pass1 – deltaMV(sbIdx2). 2.16.3. Third pass – Sub-block based bidirectional optical flow MV refinement In the third pass, the refined MV is derived by applying BDOF to the 8×8 grid sub-blocks. For each 8×8 sub-block, BDOF refinement is applied to derive scaled Vx and Vy, without clipping from the refined MV of the parent block in the second pass. The derived bioMv(Vx, Vy) is rounded to 1 / 16 sample precision and clipped between -32 and 32.

[0187] The refined MVs (MV0_pass3(sbIdx3) and MV1_pass3(sbIdx3)) at the third pass are derived as follows: MV0_pass3(sbIdx3) = MV0_pass2(sbIdx2) + bioMv MV1_pass3(sbIdx3) = MV0_pass2(sbIdx2) – bioMv.

[0188] 2.17. Sample-based BDOF In sample-based BDOF, motion refinement is not based on block derivation (Vx, Vy), but is performed on a per-sample basis.

[0189] The encoding / decoding block is divided into 8×8 sub-blocks. For each sub-block, whether to apply BDOF is determined by checking the SAD between two reference sub-blocks against a threshold. If it is decided to apply BDOF to the sub-block, a sliding 5×5 window is used for each sample in the sub-block, and the existing BDOF process is applied to derive Vx and Vy for each sliding window. The derived motion refinement (Vx, Vy) is applied to adjust the bidirectionally predicted sample values ​​for the center sample of the window.

[0190] 2.18. Extended Merge Forecast In VVC, the Merge candidate list is constructed by including the following five types of candidates in sequence: (1) Airspace MVP from adjacent CU (2) Temporal MVP from co-located CU (3) Historical MVP from FIFO table (4) Paired average MVP (5) Zero MV.

[0191] The size of the Merge list is transmitted via signaling in the sequence parameter set header, and the maximum allowed size of the Merge list is 6. For each CU encoded in Merge mode, the index of the best Merge candidate is encoded using rounding univariate binarization (TU). The first bit of the Merge index is encoded using the context, and bypass encoding is used for the remaining bits.

[0192] This section provides the derivation process for various merge candidates. Similar to HEVC, VVC also supports parallel derivation of the merge candidate list for all CUs within a region of a certain size.

[0193] 2.18.1. Derivation of Airspace Candidates The derivation of spatial merge candidates in VVC is the same as in HEVC, except that the positions of the first two merge candidates are swapped. At most four merge candidates are selected from those at the indicated positions. The derivation order is B0, A0, B1, A1, and B2. Position B2 is considered only if one or more CUs at positions B0, A0, B1, and A1 are unavailable (e.g., because it belongs to another stripe or slice) or if it is intra-frame encoded / decoded. After adding the candidate at position A1, a redundancy check is performed on the remaining candidates. This check ensures that candidates with the same motion information are excluded from the list, thus improving encoding / decoding efficiency. To reduce computational complexity, not all possible candidate pairs are considered in the redundancy check. Instead, only... Figure 24 The system uses arrow links to select pairs, and only adds candidates to the list if the corresponding candidates used for redundancy checks do not have the same motion information.

[0194] 2.18.2. Derivation of Time-Domain Candidates In this step, only one candidate is added to the list. Specifically, in the derivation of this temporal merge candidate, the scaled motion vector is derived based on the co-located CU belonging to the co-located reference image. The list of reference images to be used for the derivation of the co-located CU is explicitly transmitted via signal transmission in the strip header. Figure 25As shown by the dashed lines, the scaled motion vectors of the temporal merge candidate are obtained by scaling the motion vectors of the co-located CU using the POC distances tb and td, where tb is defined as the POC difference between the current image and the reference image, and td is defined as the POC difference between the co-located reference image and the co-located image. The reference image index of the temporal merge candidate is set to 0.

[0195] like Figure 26 As shown, the position for the temporal candidate is selected between candidate C0 and C1. If the CU at position C0 is unavailable, intra-frame encoded or decoded, or outside the current line of the CTU, position C1 is used. Otherwise, position C0 is used for the derivation of the temporal merge candidate.

[0196] 2.18.3. Historical Merge Candidate Derivation Historically based MVP (HMVP) merge candidates are added to the merge list, following the spatial MVP and TMVP. In this method, motion information from previously encoded / decoded blocks is stored in a table and used as the MVP for the current CU. The table with multiple HMVP candidates is maintained during the encoding / decoding process. The table is reset (cleared) when a new CTU row is encountered. Whenever a CU that is not inter-frame encoded / decoded in a sub-block is encountered, the associated motion information is added to the last entry of the table as a new HMVP candidate.

[0197] The HMVP table size S is set to 6, indicating that a maximum of 6 history-based MVP (HMVP) candidates can be added to the table. When a new motion candidate is inserted into the table, a constrained First-In-First-Out (FIFO) rule is used, where a redundancy check is first applied to find if a duplicate HMVP exists in the table. If found, the duplicate HMVP is removed from the table, and all subsequent HMVP candidates are shifted forward. HMVP candidates can be used in the Merge candidate list construction process. The latest few HMVP candidates in the table are checked sequentially and inserted into the candidate list after the TMVP candidates. Redundancy checks are applied between HMVP candidates and spatial or temporal Merge candidates.

[0198] To reduce the number of redundant check operations, the following simplifications are introduced: The number of HMPV candidates used for generating the Merge list is set to (N<=4)?M:(8-N), where N indicates the number of existing candidates in the Merge list and M indicates the number of available HMVP candidates in the table.

[0199] Once the total number of available Merge candidates reaches the maximum allowed Merge candidates minus 1, the process of building the Merge candidate list from the HMVP is terminated.

[0200] 2.18.4. Derivation of Pairwise Average Merge Candidates Pairwise averaging candidates are generated by averaging predefined candidate pairs from an existing Merge candidate list. These predefined pairs are defined as {(0, 1), (0, 2), (1, 2), (0, 3), (1, 3), (2, 3)}, where the numbers represent the Merge indices in the Merge candidate list. The averaged motion vector is calculated separately for each reference list. If two motion vectors are available in a list, they are averaged even if they point to different reference images; if only one motion vector is available, that vector is used directly; if no motion vector is available, the list remains invalid.

[0201] When the Merge list is not full after pairwise average Merge candidates are added, zero MVP will be inserted at the end until the maximum number of Merge candidates is reached.

[0202] 2.18.5. Merge estimation region The Merge Estimation Region (MER) allows for the independent derivation of Merge candidate lists for CUs within the same Merge Estimation Region (MER). Candidate blocks located within the same MER as the current CU are not included in the generation of the Merge candidate list for the current CU. Furthermore, the update process for the historical motion vector prediction candidate list is only updated if (xCb + cbWidth) >> Log2ParMrgLevel is greater than xCb >> Log2ParMrgLevel and (yCb + cbHeight) >> Log2ParMrgLevel is greater than (yCb >> Log2ParMrgLevel), where (xCb, yCb) is the top-left brightness sample position of the current CU in the image, and (cbWidth, cbHeight) is the CU size. The MER size is selected on the encoder side and signaled as log2_parallel_merge_level_minus2 in the sequence parameter set.

[0203] 2.19. New Merge Candidates 2.19.1. Derivation of Non-Adjacent Merge Candidates In VVC, Figure 27 The five spatial neighbor blocks and one temporal nearest neighbor shown were used to derive the Merge candidate.

[0204] We propose using the same pattern as in VVC to derive additional merge candidates from positions not adjacent to the current block. To achieve this, for each search round i, a virtual block is generated based on the current block, as follows: First, the relative position of the virtual block to the current block is calculated using the following formula: Offsetx =-i×gridX, Offsety = -i×gridY Offsetx and Offsety represent the offset of the top-left corner of the virtual block relative to the top-left corner of the current block, and gridX and gridY are the width and height of the search grid.

[0205] Secondly, the width and height of the virtual block are calculated using the following formula: newWidth = i×2×gridX+ currWidthnewHeight = i×2×gridY +currHeight.

[0206] Where currWidth and currHeight are the width and height of the current block. newWidth and newHeight are the width and height of the new virtual block.

[0207] gridX and gridY are currently set to currWidth and currHeight, respectively.

[0208] Figure 28 This illustrates the relationship between the virtual block and the current block.

[0209] After the virtual block is generated, block A i B i C i D i and E i These can be considered VVC spatial neighbor blocks, and their positions are obtained using the same pattern as the pattern in the VVC. Clearly, if the search round i is 0, the virtual block is the current block. In this case, block A... i B i C i D i and E i It is a spatial neighbor block used in VVC Merge mode.

[0210] When constructing the Merge candidate list, deduplication is performed to ensure that each element in the Merge candidate list is unique. The maximum search round is set to 1, which means that five non-adjacent spatial neighbor blocks are utilized.

[0211] Non-adjacent spatial domain merge candidates are inserted into the merge list after the temporal domain merge candidates in the order B1->A1->C1->D1->E1.

[0212] 2.19.2. STMVP We propose using three spatial merge candidates and one temporal merge candidate to derive the average candidate as the STMVP candidate.

[0213] STMVP is inserted before the Merge candidate in the upper left airspace.

[0214] STMVP candidates were deduplicated along with all previous Merge candidates in the Merge list.

[0215] For airspace candidates, the top three candidates in the current Merge candidate list are used.

[0216] For time-domain candidates, use the same position as the VTM / HEVC co-position.

[0217] For airspace candidates, the first, second, and third candidates inserted into the current Merge candidate list before STMVP are denoted as F, S, and T.

[0218] A time-domain candidate with the same position as the VTM / HEVC co-position used in TMVP is denoted as Col.

[0219] The motion vector (denoted as mvLX) of the STMVP candidate in the prediction direction X is derived as follows: 1) If the reference indices of the four Merge candidates are all valid and equal to 0 in the prediction direction X (X = 0 or 1), then mvLX = (mvLX_F + mvLX_S + mvLX_T + mvLX_Col)>>2.

[0220] 2) If the reference indices of three out of the four merge candidates are valid and equal to 0 in the prediction direction X (X = 0 or 1), then mvLX = (mvLX_F × 3 + mvLX_S × 3 + mvLX_Col × 2)>>3 or mvLX = (mvLX_F × 3 + mvLX_T × 3 + mvLX_Col × 2)>>3 or mvLX = (mvLX_S × 3 + mvLX_T × 3 + mvLX_Col × 2)>>3.

[0221] 3) If the reference indices of two of the four merge candidates are valid and equal to 0 in the prediction direction X (X = 0 or 1), then mvLX = (mvLX_F + mvLX_Col)>>1 or mvLX = (mvLX_S + mvLX_Col)>>1 or mvLX = (mvLX_T + mvLX_Col)>>1.

[0222] Note: STMVP mode is turned off if time-domain candidates are not available.

[0223] 2.19.3. Merge List Size If both non-adjacent Merge candidates and STMVP Merge candidates are considered, the size of the Merge list is signaled in the sequence parameter set header, and the maximum allowed size of the Merge list is 8.

[0224] 2.20. Geometric Partitioning (GPM) In VVC, geometric segmentation modes are supported for inter-frame prediction. Geometric segmentation modes are transmitted via signaling using CU-level flags as a merge mode. Other merge modes include regular merge mode, MMVD mode, CIIP mode, and sub-block merge mode. Geometric segmentation modes are tailored to each possible CU size ( ,in Excluding 8x64 and 64x8, a total of 64 partitions are supported.

[0225] When using this mode, the CU is divided into two parts by a straight line of geometric positioning ( Figure 29 The position of the segmentation line is mathematically derived from the angle and offset parameters of a specific segment. Each part of the geometric segmentation in the CU is predicted inter-frame using its own motion; only unidirectional prediction is allowed for each segment, i.e., each part has one motion vector and one reference index. Unidirectional prediction motion constraints are applied to ensure that, as with regular bidirectional prediction, only two motion-compensated predictions are needed per CU. The unidirectional prediction motion for each segment is derived using the process described in 2.20.1.

[0226] If a geometric segmentation mode is used for the current CU, the geometric segmentation index (angle and offset) and two merge indices (one for each segment) are further indicated by signal transmission. The number of maximum GPM candidate sizes is explicitly transmitted in SPS via signal transmission, and the syntax binarization used for the GPM merge indices is specified. After predicting each part of the geometric segmentation, a blending process with adaptive weights, as described in 2.20.2, is used to adjust the sample values ​​along the geometric segmentation edges. This is the prediction signal for the entire CU, and the transformation and quantization processes are applied to the entire CU as in other prediction modes. Finally, the motion field of the CU predicted using the geometric segmentation mode is stored as described in 2.20.3.

[0227] 2.20.1. Construction of One-Way Prediction Candidate List The unidirectional prediction candidate list is directly derived from the Merge candidate list constructed according to the extended Merge prediction process in 2.18. Let n denote the index of the unidirectional prediction motion in the geometric unidirectional prediction candidate list. The LX motion vector of the nth extended Merge candidate (where X equals the parity of n) is used as the nth unidirectional prediction motion vector for the geometric segmentation pattern. These motion vectors in... Figure 30 The value is marked with "x". If the corresponding LX motion vector of the nth extended Merge candidate does not exist, the L(1-X) motion vector of the same candidate is used as the unidirectional predicted motion vector for the geometric segmentation pattern.

[0228] 2.20.2. Blending along geometrically segmented edges After predicting each part of the geometric segment using its own motion, a blend is applied to the two predicted signals to derive samples around the segmentation edges. The blending weights for each location of the CU are derived based on the distance between the individual location and the segmentation edge.

[0229] For location The distance to the segmentation edge is derived as follows:

[0230] in It is an index for the angle and offset of the geometric segmentation, which depends on the geometric segmentation index transmitted via signal. The sign depends on the angle index i.

[0231] The weights of each part of the geometric segment are derived as follows:

[0232] partIdx depends on the angle index i. An example in Figure 31 It is shown in the middle.

[0233] 2.20.3. Motion field storage for geometric segmentation patterns Mv1 from the first part of the geometric segmentation, Mv2 from the second part of the geometric segmentation, and the combination Mv of Mv1 and Mv2 are stored in the motion field of the CU encoded and decoded by the geometric segmentation pattern.

[0234] The type of motion vector stored for each individual location in the sports field is determined as follows:

[0235] Where motionIdx equals It is recalculated from equation (2-18).

[0236] partIdx depends on the angle index .

[0237] If sType equals 0 or 1, then Mv0 or Mv1 is stored in the corresponding motion field. Otherwise, if sType equals 2, then the combined Mv from Mv0 and Mv2 is stored. The combined Mv is generated using the following process: 1) If Mv1 and Mv2 come from different lists of reference images (one from L0 and the other from L1), then Mv1 and Mv2 are simply combined to form a bidirectional predicted motion vector.

[0238] Otherwise, if Mv1 and Mv2 come from the same list, only the unidirectional predicted motion Mv2 is stored.

[0239] 2.21. Multiple Hypothesis Prediction In multiple hypothesis prediction (MHP), in addition to inter-frame AMVP mode, regular Merge mode, affine Merge mode, and MMVD mode, up to two additional prediction values ​​are transmitted via signaling. The resulting overall prediction signal is iteratively accumulated with each additional prediction signal.

[0240] The weighting factor α is specified according to Table 2-4 below.

[0241] Table 2-4 – Weighting Factors for MHP

[0242] For inter-frame AMVP mode, MHP is only applied when unequal weights are selected in BCW in bidirectional prediction mode.

[0243] Additional assumptions can be either Merge or AMVP mode. In Merge mode, motion information is indicated by the Merge index, and the Merge candidate list is the same as in the geometric segmentation mode. In AMVP mode, the reference index, MVP index, and MVD are transmitted via signals.

[0244] 2.22. Non-adjacent airspace candidates Non-adjacent airspace merge candidates are inserted after the TMVP in the regular merge candidate list. The style of airspace merge candidates is as follows: Figure 32 The distance between non-adjacent spatial domain candidates and the current codec block is shown in the diagram. The distance between the current codec block and the candidate spatial domain is based on the width and height of the current codec block.

[0245] 2.23. Template Matching (TM) Template matching (TM) is a decoder-side MV derivation method used to refine the motion information of the current CU by finding the closest match between a template in the current image (i.e., the top and / or left neighboring blocks of the current CU) and a block in the reference image (i.e., of the same size as the template). For example... Figure 33 As shown, a better MV is searched around the initial motion of the current CU within a search range of [-8, +8] pixels. Two modifications to template matching are proposed: determining the search step size based on AMVR mode, and allowing TM to be cascaded with a bilateral matching process in Merge mode.

[0246] In AMVP mode, MVP candidates are determined based on template matching error. The TM process picks the MVP candidate that minimizes the difference between the current block template and the reference block template, and then performs MV refinement only on that specific MVP candidate. The TM refines the MVP candidate using an iterative diamond search, starting with full-pixel MVD precision (or 4 pixels for 4-pixel AMVR mode) within a search range of [-8, +8] pixels. AMVP candidates can be further refined using a cross search with full-pixel MVD precision (or 4 pixels for 4-pixel AMVR mode), followed by half-pixels and quarter-pixels sequentially according to the AMVR mode specified in Table 2-5. This search process ensures that the MVP candidate maintains the same MV precision as indicated by the AMVR mode after the TM process.

[0247] Table 2-5 – AMVR Search Styles and Merge Mode with AMVR

[0248] In Merge mode, a similar search method is applied to the Merge candidates indicated by the Merge index. As shown in Table 2-5, TM can proceed up to 1 / 8 pixel MVD precision, or skip those precisions beyond half-pixel MVD precision, depending on whether an alternative interpolation filter is used based on the merged motion information (i.e., used when AMVR is in half-pixel mode). Furthermore, when TM mode is enabled, template matching can operate as a standalone process or as an additional MV refinement process between block-based and sub-block-based bilateral matching (BM) methods, depending on whether BM can be enabled according to its enable condition check.

[0249] 2.24. Overlapping Block Motion Compensation (OBMC) Overlapping Block Motion Compensation (OBMC) has been previously used in H.263. In JEM, unlike H.263, OBMC can be turned on and off using CU-level syntax. When using OBMC in JEM, OBMC is performed on all motion compensation (MC) block boundaries except for the right and bottom boundaries of the CU. Furthermore, it is applied to both the luma and chroma components. In JEM, MC blocks correspond to codec blocks. When a CU is encoded and decoded using sub-CU modes (including sub-CU merge, affine, and FRUC modes), each sub-block of the CU is an MC block. To handle CU boundaries uniformly, OBMC is performed at the sub-block level on all MC block boundaries, where the sub-block size is set to equal to 4×4, such as... Figure 34 As shown.

[0250] When OBMC is applied to the current sub-block, in addition to the current motion vector, the motion vectors of the four connected neighboring sub-blocks (if available and different from the current motion vector) are also used to derive the prediction block for the current sub-block. These multiple prediction blocks based on multiple motion vectors are combined to generate the final prediction signal for the current sub-block.

[0251] The predicted block based on the motion vectors of neighboring sub-blocks is represented as P. N , where N indicates the index for the neighboring above, below, left, and right sub-blocks, and the predicted block based on the motion vector of the current sub-block is represented as P. C When P N When based on the motion information of neighboring sub-blocks that contain the same motion information as the current sub-block, the OBMC is not removed from P. N Execute. Otherwise, P N Each sample point is added to the corresponding sample point in the PC, i.e., P N Four rows / columns are added to the PC. Weighting factors {1 / 4, 1 / 8, 1 / 16, 1 / 32} are used for P. NAnd the weighting factors {3 / 4, 7 / 8, 15 / 16, 31 / 32} were used for P. C An exception is the small MC block (i.e., when the height or width of the codec block is equal to 4 or the CU is encoded / decoded using sub-CU mode). For small MC blocks, P N Only two rows / columns were added to P C In this case, the weighting factors {1 / 4, 1 / 8} are used for P. N And the weighting factors {3 / 4, 7 / 8} were used for P. C For P generated based on the motion vectors of vertical (horizontal) neighboring sub-blocks N P N Samples in the same row (column) are added to P with the same weighting factor. C .

[0252] In JEM, for CUs with a size of 256 lumen samples or less, a CU level flag is transmitted via signaling to indicate whether OBMC is applied to the current CU. For CUs with a size greater than 256 lumen samples or not encoded / decoded using AMVP mode, OBMC is applied by default. At the encoder, when OBMC is applied to the CU, its effect is considered during the motion estimation phase. The predicted signal formed by OBMC using motion information from the top and left neighbor blocks is used to compensate for the top and left boundaries of the original signal of the current CU, and then the normal motion estimation process is applied.

[0253] 2.25. Multiple Transform Selection (MTS) for Core Transformation In addition to DCT-II, which is used in HEVC, the Multiple Transform Selection (MTS) scheme is also used for residual coding and decoding of both inter-frame and intra-frame codec blocks. It uses multiple transforms selected from DCT8 / DST7. The newly introduced transform matrices are DST-VII and DCT-VIII. Table 2-6 shows the basis functions of the selected DST / DCT.

[0254] Table 2-6 – Transform basis functions for DCT-II / VIII and DSTVII for N-point inputs

[0255] To maintain the orthogonality of the transformation matrices, the transformation matrices are quantized more accurately than those in HEVC. To keep the intermediate values ​​of the transformation coefficients within the 16-bit range, all coefficients must have 10 bits after both the horizontal and vertical transformations.

[0256] To control the MTS scheme, separate enable flags are specified at the SPS level for intra-frame and inter-frame operations. When MTS is enabled at SPS, a CU-level flag is signaled to indicate whether MTS is applied. Here, MTS is applied only to luminance. MTS signal transmission is skipped when one of the following conditions is met.

[0257] – The position of the last significant coefficient of luminance TB is less than 1 (i.e., DC only); – The last significant coefficient of luminance TB is located in the MTS zero region.

[0258] If the MTS CU flag is equal to 0, DCT2 is applied in both directions. However, if the MTS CU flag is equal to 1, two additional flags are transmitted via signaling to indicate the transform type for the horizontal and vertical directions, respectively. The transform and signaling mapping table is shown in Table 2-7. By removing intra-frame mode and block shape dependencies, a unified transform selection for ISP and implicit MTS is used. If the current block is in ISP mode, or if the current block is an intra-frame block and both intra-frame explicit MTS and inter-frame explicit MTS are enabled, only DST7 is used for both the horizontal and vertical transform cores. When transform matrix precision is involved, an 8-bit master transform core is used. Therefore, all transform cores used in HEVC remain unchanged, including 4-point DCT-2 and DST-7, 8-point, 16-point, and 32-point DCT-2. In addition, other transform cores (including 64-point DCT-2, 4-point DCT-8, 8-point, 16-point, and 32-point DST-7 and DCT-8) use an 8-bit master transform core.

[0259] Table 2-7 – Transformation and Signal Transmission Mapping Table

[0260] To reduce the complexity of large-sized DST-7 and DCT-8 blocks, the high-frequency transform coefficients are zeroed for DST-7 and DCT-8 blocks with dimensions (width or height, or both) equal to 32. Only the coefficients in the 16×16 low-frequency region are retained.

[0261] Similar to HEVC, block residuals can be encoded and decoded using transform skip mode. To avoid redundancy in syntax encoding and decoding, the transform skip flag is not signaled when the CU-level MTS_CU_flag is not equal to 0. Note that when LFNST or MIP is activated for the current CU, the implicit MTS transform is set to DCT2. Implicit MTS can also be enabled when MTS is enabled for inter-frame encoding / decoding blocks.

[0262] 2.26. Subblock Transformation (SBT) In VTM, a sub-block transform is introduced for inter-frame prediction CUs. In this transform mode, only a sub-part of the residual block is encoded or decoded for the CU. When the inter-frame prediction CU has cu_cbf equal to 1, the signal cu_sbt_flag can be used to indicate whether the entire residual block or a sub-part of the residual block is encoded or decoded. In the former case, the inter-frame MTS information is further parsed to determine the transform type of the CU. In the latter case, a portion of the residual block is encoded or decoded using a presumed adaptive transform, and another portion of the residual block is zeroed out.

[0263] When SBTs are used in inter-frame encoding / decoding CUs, the SBT type and SBT position information are transmitted via signals in the bitstream. For example... Figure 35 As shown, there are two SBT types and two SBT locations. For SBT-V (or SBT-H), the TU width (or height) can be equal to half the CU width (or height) or 1 / 4 of the CU width (or height), resulting in a 2:2 partition or a 1:3 / 3:1 partition. A 2:2 partition is like a binary tree (BT) partition, while a 1:3 / 3:1 partition is like an asymmetric binary tree (ABT) partition. In an ABT partition, only small regions contain non-zero residuals. If one dimension of the CU is 8 in the luma sample, a 1:3 / 3:1 partition along that dimension is prohibited. There can be a maximum of 8 SBT modes for a CU.

[0264] Position-dependent transform core selection is applied to the luma transform blocks in SBT-V and SBT-H (chroma TB always uses DCT-2). Two positions in SBT-H and SBT-V are associated with different core transforms. More specifically, the horizontal and vertical transforms for each SBT position are... Figure 35 The transformations are specified in the code. For example, the horizontal and vertical transformations for SBT-V position 0 are DCT-8 and DST-7, respectively. When one side of the residual TU is greater than 32, the transformations in both dimensions are set to DCT-2. Therefore, the sub-block transformations jointly specify the TU slice, cbf, and horizontal and vertical core transformation types of the residual block.

[0265] SBT is not applied to CUs encoded and decoded using a combination of inter-frame and intra-frame modes.

[0266] 2.27. Adaptive Merge Candidate Reordering Based on Template Matching To improve encoding and decoding efficiency, after constructing the merge candidate list, the order of each merge candidate is adjusted based on the template matching cost. The merge candidates are arranged in the list according to their ascending template matching cost. This is done in subgroups.

[0267] Template matching cost is measured by the sum of absolute differences (SAD) between the current CU's neighboring samples and their corresponding reference samples. If the merge candidate includes bidirectional predicted motion information, then... Figure 36 As shown, the corresponding reference sample is the average of the corresponding reference sample in reference list 0 and the corresponding reference sample in reference list 1. If the Merge candidate includes sub-CU level motion information, then as follows... Figure 37 As shown, the corresponding reference sample point is composed of the neighboring sample points of the corresponding reference sub-block.

[0268] like Figure 38 As shown, the sorting process is performed in subgroups. The first three merge candidates are sorted together. The last three merge candidates are sorted together. The template size (width of the left template or height of the top template) is 1. The subgroup size is 3.

[0269] 2.28. Adaptive Merge Candidate List We can assume there are 8 merge candidates. The first 5 merge candidates are designated as the first subgroup, and the last 3 merge candidates are designated as the second subgroup (i.e., the last subgroup).

[0270] For the encoder, after constructing the Merge candidate list, as follows Figure 39 As shown, some merge candidates are adaptively reordered in ascending order of merge candidate costs. More specifically, the template matching cost of merge candidates in all subgroups except the last subgroup is computed; then, merge candidates in each subgroup except the last subgroup are reordered; finally, the final merge candidate list is obtained.

[0271] For the decoder, after constructing the Merge candidate list, such as Figure 40 As shown, some / no merge candidates are adaptively reordered in ascending order at the merge candidate cost. Figure 40 In this context, the subgroup containing the selected (transmitted via signal) Merge candidate is referred to as the selected subgroup.

[0272] More specifically, if the selected Merge candidate is in the last subgroup, the Merge candidate list construction process is terminated after deriving the selected Merge candidate, no reordering is performed, and the Merge candidate list remains unchanged; otherwise, the process is as follows: After deriving all Merge candidates in the selected subgroup, the Merge candidate list construction process is terminated; the template matching cost of the Merge candidates in the selected subgroup is calculated; the Merge candidates in the selected subgroup are reordered; finally, a new Merge candidate list is obtained.

[0273] For both encoders and decoders The template matching cost is derived as a function of T and RT, where T is the set of samples in the template and RT is the set of reference samples for the template.

[0274] When deriving the reference sample points of the template for the Merge candidate, the motion vector of the Merge candidate is rounded to integer pixel precision.

[0275] The reference samples (RT) for the template used for bidirectional prediction are obtained by referencing the reference samples of the template in reference list 0 as follows. Reference samples of the template in Reference List 1 It is derived by weighted averaging.

[0276]

[0277] The weights (8-w) of the reference templates in reference list 0 and the weights (w) of the reference templates in reference list 1 are determined by the BCW indices of the Merge candidates. The BCW indices equal to {0,1,2,3,4} correspond to w equal to {-2,3,4,5,10}, respectively.

[0278] If the Local Illumination Compensation (LIC) flag of the Merge candidate is true, the reference sample points of the template are derived using the LIC method.

[0279] Template matching cost is calculated based on the sum of absolute differences (SAD) between T and RT.

[0280] The template size is 1. This means that the width of the left template and / or the height of the top template is 1.

[0281] If the encoding / decoding mode is MMVD, the Merge candidates used to derive the base Merge candidates are not reordered.

[0282] If the encoding / decoding mode is GPM, the Merge candidates used to derive the one-way prediction candidate list are not reordered.

[0283] 2.29. IBC with Extended Reference Area An IBC reference area design that does not increase the current memory area required by ECM-3 is proposed and its performance is tested.

[0284] Figure 41The design is illustrated. In the figure, the blue squares represent the current CTU, and the green squares represent CTUs that can be used by the IBC reference. Specifically, assuming W represents the maximum horizontal CTU index and the current CTU index is (m, n), for the codec units in the current CTU, there are reference areas that can be used by the IBC for CTU definitions with indices (0, n)...(m, n) and (m-1, n)...(W, n).

[0285] One reason for this design is that in the current ECM, the CTUs on the left, top, and top-left are in use and therefore need to be preserved. To achieve this, all CTUs to the right of the top CTU in the top CTU row (for CTUs to be encoded / decoded in the current CTU row) and all CTUs to the left of the current CTU in the current CTU row (for CTUs to be encoded / decoded in the next CTU row) must be preserved. This means that this design does not increase the cache size required by the current ECM.

[0286] 2.30. IBC with Template Matching It is proposed that template matching be used with IBC for both the IBC Merge pattern and the IBC AMVP pattern.

[0287] Compared to the list used in the regular IBC Merge mode, the IBC-TM Merge list has been modified so that candidates are selected based on a deduplication method, where the motion distance between candidates is the same as in the regular TM Merge mode. The ending zero motion satisfying (which is meaningless with respect to intra-frame encoding and decoding) has been replaced by the motion vectors of the left (-W, 0), top (0, -H), and upper left (-W, -H) CUs, and then, if necessary, the list is satisfied with the leftmost one without deduplication.

[0288] In IBC-TM Merge mode, the selected candidate is refined using a template matching method before the RDO or decoding process. IBC-TM Merge mode competes with the regular IBC Merge mode, and the TM-Merge flag is transmitted via signaling.

[0289] In the IBC-TM AMVP mode, up to three candidates are selected from the IBC Merge list. Each of these three candidates is refined using a template matching method and ranked according to its resulting template matching cost. Then, typically only the top two are considered in the motion estimation process.

[0290] Because the IBC motion vector is constrained to integers and in such a way Figure 42Within the reference area shown, template matching refinement for both IBC-TM Merge and AMVP modes is relatively straightforward. Therefore, in IBC-TM Merge mode, all refinements are performed with integer precision, while in IBC-TM AMVP mode, they are performed with either integer precision or 4-pixel precision. In both cases, the motion vectors refined in each refinement step must adhere to the constraints of the reference area.

[0291] 2.31. Reconstructing the Reordered IBC (RR-IBC) Screen content codecs such as Intra-Block Copy (IBC) generate predictive blocks by directly copying previously encoded reference regions from the same frame. Symmetry is frequently observed in video content, particularly in text character regions and computer-generated graphics within sequences of screen content, such as… Figure 43 As shown. Therefore, screen-specific content encoding / decoding tools that take symmetry into account will effectively compress such video content.

[0292] A Reconstruction Reordering IBC (RR-IBC) mode is proposed for screen content video encoding and decoding. When applied, samples in the reconstructed block are flipped according to the flip type of the current block. On the encoder side, the original block is flipped before motion search and residual calculation, while the prediction block is derived without flipping. On the decoder side, the reconstructed block is flipped back to recover the original block.

[0293] For blocks encoded and decoded using RR-IBC, two flipping methods are supported: horizontal flipping and vertical flipping. First, for blocks encoded and decoded using IBC AMVP, a syntax flag is signaled to indicate whether the reconstruction has been flipped. If it has been flipped, another flag is further signaled to specify the flipping type. For IBC Merge, the flipping type is inherited from the neighboring block without syntax signaling. Considering horizontal or vertical symmetry, the current block and the reference block are typically aligned horizontally or vertically. Therefore, when a horizontal flip is applied, the vertical component of the BV is not signaled and is presumed to be equal to 0. Similarly, when a vertical flip is applied, the horizontal component of the BV is not signaled and is presumed to be equal to 0.

[0294] To better utilize symmetry, a flip-aware BV adjustment method is applied to refine block vector candidates. For example, as Figure 44A and Figure 44B As shown, (x nbr y nbr ) and (x cur y cur ) represent the coordinates of the center sample points of neighboring blocks and the current block, respectively, BV nbr and BV curThese represent the BV of the neighboring block and the current block, respectively. When the neighboring block is encoded and decoded using horizontal flipping, the BV... cur The horizontal component does not inherit BV directly from neighboring blocks, but rather through BV... nbr The horizontal component (denoted as BV) nbr h Add motion shift to calculate, i.e., BV cur h =2(x) nbr -xcur)+BV nbr h Similarly, when neighboring blocks are encoded and decoded using vertical flipping, BV cur The vertical component is transmitted through BV nbr The vertical component (denoted as BV) nbr v Add motion shift to calculate, i.e., BV cur v =2(y nbr -y cur )+BV nbr v .

[0295] 2.32. Intra-frame template matching prediction Intra-frame template matching prediction (intra-frame TMP) is a special intra-frame prediction mode that copies the best prediction block from the reconstructed portion of the current frame, whose L-shaped template matches the current template. For a predefined search range, the encoder searches the reconstructed portion of the current frame for the template most similar to the current template and uses the corresponding block as the prediction block. The encoder then transmits the use of this mode via signaling, and the same prediction operation is performed on the decoder side.

[0296] The prediction signal is obtained by comparing the L-shaped causal nearest neighbors of the current block with... Figure 45 This is generated by matching another block in a predefined search area, which includes: R1: Current CTU; R2: Top left CTU; R3: Above CTU; R4: Left CTU.

[0297] SAD was used as the cost function.

[0298] Within each region, the decoder searches for the template with the minimum SAD relative to the current template and uses its corresponding block as the prediction block.

[0299] The dimensions of all regions (SearchRange_w, SearchRange_h) are set to be proportional to the block dimensions (BlkW, BlkH) to have a fixed number of SAD comparisons per pixel. That is: SearchRange_w = a BlkW, SearchRange_h = a BlkH in" "" is a constant that controls the trade-off between gain and complexity. In practice, " a "Equals 5. Enables intra-frame template matching for CUs with width and height dimensions less than or equal to 64. This maximum CU size for intra-frame template matching is configurable."

[0300] When DIMD is not used in the current CU, the intra-template matching prediction mode is transmitted at the CU level via a dedicated flag.

[0301] 2.33 Intra-frame prediction fusion Intra-frame prediction fusion methods use multiple predictions generated from different modes / reference lines.

[0302] In subtest a, multiple intra-frame predictions are generated and then fused using a weighted average. The process of deriving the predictions to be used in the fusion process is described below: 1) For the intra-angle prediction mode in a single-mode case including TIMD and DIMD, the proposed method, by representing it as... Intra-prediction is derived by weighting the intra-prediction obtained from multiple reference rows, where It is an intra-frame prediction from the default reference line, and This is a prediction from the row above the default reference row. The weights are set to... .

[0303] 2) For TIMD modes with hybrid patterns, Used in the first mode ,and Used in the second mode .

[0304] 3) For DIMD patterns with mixing, the number of predicted values ​​selected for the weighted average is increased from 3 to 6.

[0305] In subtest b, intra-frame prediction fusion is performed on the reference lines instead of the prediction blocks. The two reference lines (referred to as...) This is used for intra-frame prediction fusion. The corresponding intra-frame prediction angle is considered during the fusion process. Each value in the reference row of the merge ( It is derived from the following: .

[0306] When the intra-frame mode has a non-integer slope (required reference sample interpolation) and the block size is greater than 16, the proposed intra-frame prediction fusion is applied to the luma block, used together with MRL, but not applied to the ISP-encoded block. In the method studied in subtest a, PDPC is applied for the intra-frame prediction mode that uses the closest reference line to the current block.

[0307] 2.34 Template-based Multi-Reference Line Intra-Frame Prediction (TMRL) The proposed TMRL model includes the following aspects: a) Expanded reference line candidate list and intra-prediction mode candidate list.

[0308] The extended reference line candidate list used in this proposal is {1, 3, 5, 7, 12}. The restrictions on the top CTU line remain unchanged. The size of the intra-prediction mode candidate list is 10. The construction of the intra-prediction mode candidate list is similar to that of MPM. The differences are: Planar modes were excluded from the proposed list of intra-prediction mode candidates. DC modes were added after the modes of the five nearest-neighbor PUs and the DIMD mode, if they were not already included.

[0309] With from arrive An angle mode with an incremental angle (compared to existing angle modes in the intra-prediction mode candidate list) has been added.

[0310] b) Construction of the TMRL candidate list.

[0311] For a block, there are 5 × 10 = 50 combinations of extended reference lines and allowed intra-prediction modes. Since the extended reference lines start from reference line 1, the area covered by reference line 0 is used for template matching. For template regions (see...) Figure 46 The SAD cost of the prediction (generated from 50 combinations) is calculated between prediction and reconstruction. The 20 combinations with the lowest SAD cost are selected in ascending order to form the TMRL candidate list.

[0312] c) Signaling of TMRL Instead of directly encoding and decoding the reference line and intra-frame mode, the index of the TMRL candidate list is encoded and decoded to indicate which combination of the reference line and prediction mode is used to encode and decode the current block. In the proposed TMRL mode, Golomb-Rice encoding and decoding with a division by 4 is used to encode and decode the selected combination from the combination list. The binarization process and codewords are shown in Table 2-8.

[0313] Table 2-8 – Binarization process of TMRL indexes

[0314] d) Encoder-side modification Encoder-side modifications were tested to further improve encoding / decoding efficiency. For intra-blocks larger than 8×8, if no TMRL mode is selected via SATD comparison, an additional TMRL RDO is added.

[0315] 2.35 Convolutional Cross-Component Model (CCCM) for Intra-Frame Prediction We propose to apply a convolutional cross-component model (CCCM) similar in spirit to the current CCLM model to predict chroma samples from reconstructed luminance samples. As with CCLM, when chroma downsampling is used, the reconstructed luminance samples are downsampled to match a lower-resolution chroma grid.

[0316] In addition, similar to CCLM, there are options for single-model or multi-model variants of CCCM. The multi-model variant uses two models: one derived for samples above the average luminance reference value, and the other for the remaining samples (following the spirit of the CCLM design). For PUs with at least 128 available reference samples, the multi-model CCCM mode can be selected.

[0317] 2.35.1 Convolution Filter The proposed 7-tap convolutional filter consists of a 5-tap spatial component with a sign shape, a nonlinear term, and a bias term. The input of the 5-tap spatial component of the filter comprises the center (C) luminance sample co-located with the chrominance sample to be predicted, and its top / north (N), bottom / south (S), left / west (W), and right / east (E) nearest neighbors, as shown below. Figure 47 As shown.

[0318] The nonlinear term P is expressed as the square of the center luminance sample C and scaled to the range of sample values ​​for the content: P = (C) C + midVal )>>bitDepth.

[0319] That is, for 10 bits of content, it is calculated as: P = (C C + 512)>>10.

[0320] The bias term B represents the scalar offset between the input and output (similar to the offset term in CCLM) and is set to an intermediate chroma value (512 for 10-bit content).

[0321] The output of the filter is calculated as the convolution between the filter coefficients ci and the input values, and is limited to the range of effective chromaticity samples: predChromaVal = c0C + c1N + c2S + c3E + c4W + c5P + c6B.

[0322] 2.35.2 Calculation of Filter Coefficients Filter coefficients c i It is calculated by minimizing the MSE between the predicted chromaticity samples and the reconstructed chromaticity samples in the reference area. Figure 48 The reference region is shown, consisting of six rows of chroma samples above and to the left of the PU. The reference region extends to the right by one PU width and below the PU boundary by one PU height. The region is adjusted to include only available samples. The expansion of the region shown in blue is necessary to support the "edge samples" of the plus-shaped spatial filter and is filled in unavailable areas.

[0323] MSE minimization is performed by computing the autocorrelation matrix for the luma input and the cross-correlation vector between the luma input and the chromaticity output. The autocorrelation matrix is ​​decomposed using LDL, and the final filter coefficients are computed using inverse substitution. This process largely follows the computation of ALF filter coefficients in ECM; however, LDL decomposition is chosen instead of Cholesky decomposition to avoid the use of square root operations. The proposed method uses only integer operations.

[0324] 2.35.3 Bit Stream Signal Transmission The use of this mode is signaled via PU-level flags encoded and decoded by CABAC. A new CABAC context is included to support this. When signaling is involved, CCCM is considered a sub-mode of CCLM. That is, the CCCM flag is signaled only when the intra-frame prediction mode is LM_CHROMA_IDX (to enable single-mode CCCM) or MMLM_CHROMA_IDX (to enable multi-mode CCCM).

[0325] 2.36 Gradient Linear Model (GLM) Compared to CCLM, GLM uses the gradient of luminance samples to derive a linear model, rather than downsampled luminance values. Specifically, when GLM is applied, the input to the CCLM process (i.e., downsampled luminance samples) is... Gradient of brightness sample points Replacement. Other parts of CCLM (e.g., parameter derivation, linear transformation of prediction samples) remain unchanged.

[0326]

[0327] For signal transmission, when CCLM mode is enabled for the current CU, two flags are transmitted separately for the Cb and Cr components to indicate whether GLM is enabled for each component; if GLM is enabled for a component, a syntax element is further transmitted to select one of the four gradient filters for gradient calculation.

[0328] • Enable four gradient filters for GLM, such as Figure 49 As shown, it illustrates four Soble-based gradient modes for GLM.

[0329] 3. Problem In current designs of video codec standards or video codecs (e.g., VVC, ECM), block prediction is typically derived using intra-frame prediction, inter-frame prediction, or intra-block copying, where predicted samples can be derived using interpolation or directly copied. Codec performance can be improved by refining the predicted samples using filters. 4. Detailed Implementation The following embodiments should be considered as examples to explain general concepts. These embodiments should not be interpreted in a narrow sense. Furthermore, these embodiments can be combined in any way.

[0331] Filter-based prediction 1. It is proposed that the predicted / reconstructed signal can be refined using filters for video units.

[0332] a. In one example, at least one prediction / reconstruction sample can be refined by a filter.

[0333] i. In one example, the filter can be a function with linear form.

[0334] 1) In one example, the filter could be P' = a P + b, where P and P' represent the predicted signal / sample and the refined predicted signal / sample, and a and b represent the filter parameters.

[0335] ii. In one example, the filter can be a function with a nonlinear form.

[0336] 1) In one example, the filter could be P' = a P + b P^2 + c, where P and P' represent the predicted signal / sample and the refined predicted signal / sample, and a, b, and c represent the filter parameters.

[0337] 2) In one example, the filter could be P' = a P + b P P1+c, where P, P1, and P' represent the first predicted signal / sample, the second predicted signal / sample, and the refined predicted signal / sample, and a, b, and c represent the filter parameters.

[0338] iii. In one example, the input values ​​to the filter can be either predicted samples or reconstructed samples.

[0339] 1) In one example, whether the input value is a predicted sample or a reconstructed sample can depend on the location of the sample to be filtered.

[0340] iv. In one example, the input values ​​to the filter can be filled samples.

[0341] 1) In one example, whether the input value is a filled sample can depend on the location of the sample to be filtered.

[0342] v. In one example, a right shift operation can be used after a filter.

[0343] vi. In one example, the clipping operation can be used after the filter.

[0344] vii. In one example, one or more neighboring predicted samples of the current predicted sample can be used in the filter.

[0345] 1) In one example, neighboring samples can be in the horizontal / vertical / 45-degree / 135-degree direction. Example in... Figure 50A , Figure 50B , Figure 50C and Figure 50D It is shown in the middle.

[0346] 2) In one example, neighboring samples can be in the shape of a cross / diamond / square. Example in... Figure 50E , Figure 50F and Figure 50G It is shown in the middle.

[0347] 3) In one example, gradient information from neighboring samples is used in the filter.

[0348] viii. In one example, one or more neighboring reconstructed samples of the current video unit can be used in a filter.

[0349] ix. In one example, location / positional information can be used in a filter.

[0350] 1) In one example, the horizontal and / or vertical distance between the current sample point and the upper left / left boundary / upper boundary position of the current video unit can be used.

[0351] b. In one example, a filter can be used with one or more intra-frame codecs.

[0352] i. In one example, intra-frame codec tool can refer to a specific codec tool, such as regular intra-frame prediction, DIMD, TIMD, MRL, ISP, MIP, IntraTMP, intra-frame prediction fusion, SGPM, TMRL, PDPC / gradient PDPC, CCLM, MMLM, CCCM, GLM, chroma fusion or a variant thereof.

[0353] c. In one example, a filter can be used with one or more inter-frame encoding / decoding tools.

[0354] i. In one example, inter-frame codec tool can refer to a specific codec tool, such as CIIP (e.g., CIIP-plane, CIIP-TIMD, CIIP-TM), BCW (e.g., BCW index derived by TM), MMVD (e.g., MMVD or TM-based MMVD reordering), template matching (TM), affine (e.g., affine-MMVD, TM-based affine MMVD reordering), DMVR / multi-pass DMVR, PROF, BDOF or sample-based BDOF, adaptive decoder-side motion vector refinement (ADMVR), OBMC or TM-based OBMC, MHP, GPM (e.g., GPM, GPM-TM, GPM-MMVD, GPM-intra), bilateral / template matching AMVP-Merge mode or variations thereof.

[0355] d. In one example, a filter can be used with one or more IBC codecs.

[0356] i. In one example, the IBC codec tool refers to the IBC AMVP mode, which may refer to the normal IBC AMVP, or the TM-based IBC AMVP, or the RR-IBC AMVP mode, or other IBC AMVP modes in which the BV prediction value is derived and the BVD is transmitted / derived through signal transmission; or, the IBC Merge mode may refer to the normal IBC Merge mode, or the IBC-TM Merge mode, or the IBC-MBVD mode, or the IBC-CIIP, or the IBC-GPM, or the IBC-LIC, or the subpixel-based IBC, or a variant thereof.

[0357] e. In one example, the filter could be used with other codec tools, such as Palette / BDPCM.

[0358] f. In one example, a filter can be used with more than one codec tool.

[0359] g. In one example, the filter parameters can be predefined.

[0360] h. In one example, the parameters of the filter can be transmitted via a signal.

[0361] i. In one example, one or more parameters of the filter can be derived.

[0362] i. In one example, one or more neighboring samples of the current video unit can be used to derive parameters.

[0363] 1) In one example, a neighboring sample can refer to the neighboring sample to the left and / or above, and / or below left, and / or above left, and / or above right of the current video unit.

[0364] 2) In one example, neighboring samples can be adjacent and / or not adjacent.

[0365] 3) In one example, neighboring samples can refer to predicted samples and / or reconstructed samples.

[0366] ii. In one example, a template composed of neighboring samples can be used to derive parameters.

[0367] 1) In one example, the template above can be used. Example in Figure 51A It is shown in the middle.

[0368] 2) In one example, the template on the left can be used. Example in... Figure 51B It is shown in the middle.

[0369] 3) In one example, the bottom left template can be used. Example in... Figure 51C It is shown in the middle.

[0370] 4) In one example, the top-right template can be used. Example in... Figure 51D It is shown in the middle.

[0371] 5) In one example, the top-left template can be used. Example in... Figure 51E It is shown in the middle.

[0372] 6) In one example, more than one item from the top / left / top right / bottom left / top left templates can be combined into a single template and used. Example in... Figures 52A to 52F It is shown in the middle.

[0373] 7) In one example, an L-shaped template can be used. Example in... Figure 53 It is shown in the middle.

[0374] 8) In one example, non-adjacent templates can be used. Example in Figure 54 It is shown in the middle.

[0375] iii. In one example, more than one template can be used to derive parameters.

[0376] 1) In one example, N templates can be used to derive parameters.

[0377] a) In one example, N=3, the top template or a combination of the top template, the left template or a combination of the left template, and the L-shaped template can be used.

[0378] b) In one example, N=3, the top template or a combination of the top template, the left template or a combination of the left template, and a combination of the top and left templates can be used.

[0379] c) In one example, N=2, the top template or a combination of the top template and the left template or a combination of the left template can be used.

[0380] d) In one example, which template is used to derive the parameters that can be transmitted or derived via signaling.

[0381] iv. In one example, the codec used for the current video unit can be used to derive the predicted samples of the template.

[0382] 1) In one example, the same motion vector (MV) as the current video unit can be used.

[0383] a) In one example, when MV is a fraction, MV is rounded to integer precision.

[0384] 2) In one example, the same block vector (BV) as the current video unit can be used.

[0385] a) In one example, when BV is a fraction, BV is rounded to integer precision.

[0386] 3) In one example, the same intra-frame prediction method as the current video unit can be used.

[0387] 4) Alternatively, modified encoding and decoding tools can be used to derive the predicted samples of the template.

[0388] v. In one example, the method can be applied to derive parameters using a set of training samples by minimizing the difference between the true value (G) and the prediction (P) of the training samples.

[0389] 1) In one example, difference can refer to absolute transformation difference (SATD), sum of squared errors (SSE), or sum of absolute differences (SAD), or mean-reduced sum of absolute differences (MRSAD), or subjective quality measure (e.g., structural similarity index measure (SSIM)).

[0390] a) Alternatively, the difference can be calculated in the form of D + lambda × R, where D is a measure of distortion, such as SAD, SATD, SSE, etc., R represents the number of bits considered, and lambda is a predefined factor or an on-the-fly derived factor.

[0391] 2) In one example, G can refer to the reconstruction of the template, and P can refer to one or more prediction signals of the template.

[0392] 3) In one example, a set of training samples may include all samples of the template.

[0393] 4) In one example, a set of training samples may include at least one sample of the template.

[0394] 5) In one example, gradient information or position information can be used to derive parameters.

[0395] 6) In one example, the Least Mean Square (LMS) method can be used.

[0396] 7) In one example, the LDL method can be used, for example, the method used in CCCM.

[0397] 8) In one example, Gaussian elimination can be used, for example, as is the method used in CCCM.

[0398] 9) In one example, other methods, such as neural networks, can be used to solve for the weighted parameters by minimizing the difference between G and P.

[0399] 2. In one example, more than one prediction signal can be used in the filter.

[0400] a. In one example, all predicted signals can be used directly in the filter.

[0401] b. Alternatively, the predicted signals used in the filter may be transmitted or derived.

[0402] c. Alternatively, at least two predicted signals can be fused before being used in a filter.

[0403] d. In one example, more than one predicted signal can be divided into subgroups, and which subgroup is used in the filter can be determined by signal transmission or by derivation.

[0404] i. In one example, whether and / or how to divide into subgroups can depend on encoding / decoding information, such as block size / dimension.

[0405] 3. Whether and / or how to apply filters to video units can depend on codec information, which may refer to: a. Are specific encoding / decoding methods allowed? b. Block dimensions and / or block size c. Block depth d. Strip type / image type and / or segmentation tree type (single tree, dual tree, or local dual tree) e. Temporal layer identifier f. Block position g. Color format h. Color components i. In one example, the filter can be applied to all color components.

[0406] ii. In one example, when a filter is applied to the chroma component, the filter may be different from the filter applied to the luminance component.

[0407] iii. In one example, whether and / or how the filter is applied to the first component may depend on whether the filter is applied to the second component.

[0408] 1) In one example, the first component may refer to the chromaticity component (e.g., Cb and / or Cr), and the second component may refer to the luminance component (e.g., Y).

[0409] 2) In one example, the filter can be applied to the first component in the same way as the second component.

[0410] a) Alternatively, the filter can be applied to the first component in a different way than to the second component.

[0411] iv. In one example, the filter can be applied to the luminance component but not to the chrominance component.

[0412] 1) In one example, the luminance component can refer to Y in the YCbCr color space or G in the RGB color space.

[0413] 2) In one example, the chromaticity components can refer to Cb and / or Cr in the YCbCr color space or R and / or B in the RGB color space.

[0414] 4. The indication of the proposed filter can be conditionally transmitted via signal, wherein the conditions may include: a. Block dimensions and / or block size b. Block depth c. Strip type / image type and / or segmentation tree type (single tree, dual tree, or partial dual tree) d. Temporal layer identifier e. Block positioning f. Color format g. Color components.

[0415] 5. In one example, multiple filters can be applied.

[0416] a. In one example, the second filter can be applied to the filtering result of the first filter.

[0417] 6. Whether the current block is encoded or decoded using the proposed filter can be transmitted via signaling using one or more syntax elements.

[0418] a. In one example, a syntax element may be binarized using fixed-length encoding, rounded unary encoding, unary encoding, or EG encoding, or encoded as a flag.

[0419] b. In one example, syntax elements can be either bypassed or context-encoded.

[0420] i. The context may depend on encoded or decoded information, such as block dimensions and / or block size and / or stripe type / picture type and / or information about neighboring blocks (adjacent or non-adjacent) and / or information about other encoding / decoding tools used for the current block and / or information about the temporal layer.

[0421] c. In one example, one or more syntax elements may be transmitted via signaling at the sequence header / picture header / SPS / VPS / DPS / DCI / PPS / APS / strip header / piece group header.

[0422] d. In one example, syntax elements can be encoded and decoded in a predictive manner.

[0423] e. For example, the syntax elements of the current block can be predicted from the syntax elements of neighboring blocks.

[0424] General aspects 7. In the above examples, a video unit can refer to a color component / sub-picture / strip / piece / code-decode tree unit (CTU) / CTU line / CTU group / code-decode unit (CU) / prediction unit (PU) / transform unit (TU) / code-decode tree block (CTB) / code-decode block (CB) / prediction block (PB) / transform block (TB) / block / sub-block of a block / sub-region within a block / any other region containing more than one sample or pixel.

[0425] 8. Whether and / or how the methods disclosed above can be applied to be transmitted via signal at the sequence level / picture group level / picture level / strip level / piece group level, such as in the sequence header / picture header / SPS / VPS / DPS / DCI / PPS / APS / strip header / piece group header.

[0426] 9. Whether and / or how to apply the above methods may depend on the following information: a. Messages transmitted via signals in DPS / SPS / VPS / PPS / APS / Image Header / Strip Header / Group Header / Maximum Codec Unit (LCU) / Codec Unit (CU) / LCU Line / LCU Group / TU / PU Block / Video Codec Unit b. Location of CU / PU / TU / block / video codec unit c. Block dimensions of the current block and / or its neighboring blocks d. The block shape of the current block and / or its neighboring blocks. e. The encoding / decoding mode of the block, such as IBC or non-IBC inter-frame mode or non-IBC sub-block mode. f. Instructions for color format (e.g., 4:2:0, 4:4:4) g. Encoder / decoder tree structure h. Strip / panel type and / or image type i. Color components (e.g., applied only to the chromaticity or luminance components) j. Time-domain layer ID k. Standard grade / level / tier.

[0427] 10. The syntax elements disclosed above can be binary-coded into flags, fixed-length codes, EG(x) codes, unary codes, rounded unary codes, rounded binary codes, etc. These can be signed or unsigned.

[0428] 11. The grammatical elements disclosed above can be encoded or decoded using at least one context model. Alternatively, they can be encoded or decoded using a bypass method.

[0429] 12. The above-disclosed grammatical elements can be transmitted via signals in a conditional manner.

[0430] a. SE is transmitted via signal only when the corresponding function is applicable.

[0431] b. SE is transmitted via signal only if the dimensions of the block (width and / or height) meet the conditions.

[0432] 13. The syntax elements disclosed above can be transmitted via signaling at the block level / sequence level / picture group level / picture level / strip level / piece group level, such as in the codec structure of CTU / CU / TU / PU / CTB / CB / TB / PB, or in the sequence header / picture header / SPS / VPS / DPS / DCI / PPS / APS / strip header / piece group header.

[0433] 14. The proposed methods(s) can be combined with another codec tool, such as affine / MTS / LFNST / MMVD / MIP / ISP / CCLM / CCCM / SMVD / BDOF / DMVR / HMVP / template matching / IBC / palette / etc.

[0434] 15. The proposed method(s) may be incompatible with another codec tool, such as affine / MTS / LFNST / MMVD / MIP / ISP / CCLM / CCCM / SMVD / BDOF / DMVR / HMVP / template matching / IBC / palette / etc.

[0435] a. In one example, if the proposed method(s) are used, the excluded codec tools are implicitly disabled without signaling.

[0436] b. In one example, if the excluded codec tools are used, the proposed method(s) are implicitly disabled without signaling.

[0437] As used herein, the term "video unit" or "video block" can be a sequence, picture, strip, slice, brick, sub-picture, codec tree unit (CTU) / codec tree block (CTB), CTU / CTB row, one or more codec units (CU) / codec blocks (CB), one or more CTU / CTB, one or more virtual pipeline data units (VPDU), or a sub-region within a picture / strip / slice / brick. The term "reference row" can refer to a row and / or column of reconstructed samples that are adjacent or non-adjacent to the current block and are used to derive the intra-prediction of the current video unit via an interpolation filter along a specific direction, and the specific direction is determined by an intra-prediction mode (e.g., conventional intra-prediction with an intra-prediction mode), or by deriving the intra-prediction of the current video unit by weighting the reference samples of the reference row using a matrix or vector (e.g., MIP).

[0438] Figure 55 A flowchart of a method 5500 for video processing according to an embodiment of the present disclosure is shown. Method 5500 is implemented during the conversion between video units of a video and a bitstream of a video.

[0439] At box 5510, for the conversion between video units and video unit bitstreams, the prediction or reconstruction of video units is refined by applying filters to the video units.

[0440] At block 5520, a transformation is performed based on the refined prediction or refined reconstruction. In some embodiments, the transformation may include encoding video units into a bitstream. Alternatively, the transformation may include decoding video units from a bitstream. Some embodiments of this disclosure can advantageously improve encoding / decoding efficiency, performance, and flexibility compared to conventional solutions.

[0441] In some embodiments, filters are used by one or more intra-frame codec tools. In some embodiments, one or more intra-frame encoding / decoding tools include at least one of the following: regular intra-frame prediction, a variant of regular intra-frame prediction, decoder-side intra-frame mode derivation (DIMD), a variant of DIMD, template-based intra-frame mode derivation (TIMD), a variant of TIMD, multiple reference lines (MRL), a variant of MRL, intra-frame sub-segmentation (ISP), a variant of ISP, matrix-weighted intra-frame prediction (MIP), a variant of MIP, IntraTMP, a variant of IntraTMP, intra-frame prediction fusion, a variant of intra-frame prediction fusion, spatial geometry segmentation mode (SGPM), a variant of SGPM, template-based multi-reference line intra-frame prediction (TMRL), a variant of TMRL, position-dependent intra-frame prediction combination (PDPC), a variant of PDPC, gradient PDPC, a variant of gradient PDPC, cross-component linear model (CCLM), a variant of CCLM, multi-model CCLM (MMLM), a variant of MMLM, convolutional cross-component model (CCCM), a variant of CCCM, gradient linear model (GLM), a variant of GLM, chroma fusion, or a variant of chroma fusion.

[0442] In some embodiments, filters are used in one or more inter-frame coding / decoding tools. For example, one or more inter-frame coding / decoding tools include at least one of the following: Intra-Inter-Frame Joint Prediction (CIIP), a variant of CIIP, Bidirectional Prediction (BCW) with Codec Unit (CU) Level Weighting, a variant of BCW, Merge Mode with Motion Vector Difference (MMVD), a variant of MMVD, Template Matching (TM), a variant of TM, Affine, a variant of Affine, Decoder-Side Motion Vector Refinement (DMVR), a variant of DMVR, Multi-Pass DMVR, a variant of Multi-Pass DMVR, and Prediction Refinement with Optical Flow (PROF). Variants of PROF, Bidirectional Optical Flow (BDOF), Variants of BDOF, Sample-based BDOF, Variants of Sample-based BDOF, Adaptive Decoder-Side Motion Vector Refinement (ADMVR), Variants of ADMVR, Overlapping Block Motion Compensation (OBMC), Variants of OBMC, TM-based OBMC, Variants of TM-based OBMC, Multiple Hypothesis Prediction (MHP), Variants of MHP, Geometric Segmentation Mode (GPM), Variants of GPM, Bilateral Matching (BM) Advanced Motion Vector Prediction (AMVP)-Merge Mode, Variants of BM AMVP-Merge Mode, TM AMVP-Merge Mode, or Variants of TM AMVP-Merge Mode. In some embodiments, CIIP includes at least one of the following: CIIP-plane, CIIP-TIMD, or CIIP-TM, and / or wherein BCE includes a BCE index derived by TM, and / or wherein MMVD includes a TM-based reordering for MMVD, and / or wherein affine includes affine-MMVD or a TM-based reordering for affine MMVD, and / or wherein GPM includes at least one of the following: GPM, GPM-TM, GPM-MMVD, or GPM-intraframe.

[0443] In some embodiments, filters are used in one or more intra-block copy (IBC) codecs. For example, one or more IBC codecs include at least one of the following: IBC AMVP mode, IBC Merge mode, IBC-CIIP mode, IBC-GPM mode, IBC Local Illumination (IBC-LIC) mode, or subpixel-based IBC mode. In some embodiments, the IBC AMVP mode includes at least one of the following: normal IBC AMVP mode, TM-based IBC AMVP mode, Reconstruction Reordering (RR)-IBC AMVP mode, or other IBC AMVP modes in which block vector (BV) predictions are derived and block vector difference (BVD) is transmitted or derived through signal transmission, and / or wherein the IBC Merge mode includes at least one of the following: normal IBC Merge mode, IBC-TM Merge mode, or IBC Merge mode with block vector difference (IBC-MBVD).

[0444] In some embodiments, filters are used in other codec tools. For example, other codec tools include palette or block-based differential pulse code modulation (BDPCM).

[0445] In some embodiments, at least one predicted or reconstructed sample is refined by a filter. In some embodiments, a right shift operation is used after the filter. Alternatively or additionally, a clipping operation is used after the filter.

[0446] In some embodiments, one or more neighboring reconstructed samples of a video unit are used in a filter. In some other embodiments, one or more neighboring predicted samples of the currently predicted sample are used in a filter.

[0447] In some embodiments, one or more neighboring predicted samples are in at least one of the following directions: horizontal, vertical, 45 degrees, or 135 degrees. Examples are provided in... Figures 50A to 50D The example is shown in [the image]. In some other embodiments, one or more neighboring predicted samples are of one of the following shapes: cross-shaped, rhomboid, or square-shaped. Examples are shown in [the image]. Figures 50E to 50G The image is shown in the figure. In some other embodiments, gradient information from one or more neighboring predicted samples is used in the filter.

[0448] In some embodiments, the filter is a function of linear form. In some embodiments, the filter is P' = a P + b, where P represents the predicted signal / sample, P' represents the refined predicted signal / sample, and a and b represent the filter parameters.

[0449] In some embodiments, the filter is a function with a nonlinear form. In some embodiments, the filter is P' = a P + b P^2 + c, where P represents the predicted signal / sample, P' represents the refined predicted signal / sample, and a, b, and c represent filter parameters. In some embodiments, the filter is P' = a P + b P P1+c, where P represents the first predicted signal / sample, P1 represents the second predicted signal / sample, P' represents the refined predicted signal / sample, and a, b, and c represent filter parameters.

[0450] In some embodiments, the input values ​​to the filter are predicted samples or reconstructed samples. In some embodiments, whether the input values ​​are predicted samples or reconstructed samples depends on the location of the samples to be filtered.

[0451] In some embodiments, the input values ​​to the filter are filled samples. In other embodiments, whether the input values ​​are filled samples depends on the location of the samples to be filtered.

[0452] In some embodiments, positioning or location information is used in the filter. In some embodiments, the horizontal and / or vertical distance between the current sample and the upper left position of the video unit is used in the filter. Alternatively or additionally, the horizontal and / or vertical distance between the current sample and the left boundary position of the video unit is used in the filter. Alternatively or additionally, the horizontal and / or vertical distance between the current sample and the upper boundary position of the video unit is used in the filter.

[0453] In some embodiments, one or more parameters of the filter are derived. In some embodiments, a template including neighboring samples is used to derive one or more parameters.

[0454] In some embodiments, the top template is used. Alternatively or additionally, the left template is used. Alternatively or additionally, the bottom left template is used. Alternatively or additionally, the top right template is used. Alternatively or additionally, the top left template is used. Alternatively or additionally, more than one of the top, left, top right, bottom left, or top left templates is combined into a single template used in the filter. Alternatively or additionally, an L-shaped template is used. Alternatively or additionally, non-adjacent templates are used.

[0455] In some embodiments, multiple templates are used to derive one or more parameters. In some embodiments, a predetermined number of templates are used to derive one or more parameters.

[0456] In some embodiments, the predetermined number is 3, and an upper template or a combination template using an upper template, a left template or a combination template using a left template, and an L-shaped template are used. Alternatively or additionally, the predetermined number is 3, and an upper template or a combination template using an upper template, a left template or a combination template using a left template, and a combination template using both an upper template and a left template are used. Alternatively or additionally, the predetermined number is 2, and an upper template or a combination template using an upper template, and a left template or a combination template using a left template are used.

[0457] In some embodiments, the template used to derive one or more parameters is transmitted or derived via signal transmission. In some embodiments, a scheme is applied to derive one or more parameters using a set of training samples by minimizing the difference between the ground truth and the predictions of a set of training samples. In some embodiments, gradient information or location information is used to derive one or more parameters.

[0458] In some embodiments, the Least Mean Square (LMS) scheme is used to derive one or more parameters. Alternatively or additionally, the LDL scheme is used to derive one or more parameters, and / or Gaussian elimination is used to derive one or more parameters. In some embodiments, the difference includes at least one of the following: Absolute Transform Difference (SATD), Sum of Squared Errors (SSE), Sum of Absolute Differences (SAD), or Mean-Divided Sum of Absolute Differences (MRSAD), or a subjective quality measure. In some embodiments, the subjective quality measure is a Structural Similarity Index (SSIM) measure.

[0459] In some embodiments, the difference is calculated in the form D + lambda R, where D represents a measure of distortion, R represents the number of bits considered, and lambda is a predefined factor or an on-the-fly derived factor. In some embodiments, the ground truth comprises a reconstruction of the template, and the prediction comprises one or more predicted signals of the template. In some embodiments, a set of training samples comprises all samples of the template. Alternatively or additionally, a set of training samples comprises at least one sample of the template.

[0460] In some embodiments, another approach is used to solve for the weighted parameters by minimizing the difference between the true value and the prediction. Alternatively or additionally, another approach includes neural networks.

[0461] In some embodiments, one or more neighboring samples of a video unit are used to derive one or more parameters. In some embodiments, the one or more neighboring samples include at least one of the following: the left neighboring sample of the video unit, the top neighboring sample of the video unit, the lower left neighboring sample of the video unit, the upper left neighboring sample of the video unit, or the upper right neighboring sample of the video unit.

[0462] In some embodiments, one or more neighboring samples are adjacent and / or non-adjacent. In some embodiments, one or more neighboring samples are predicted samples and / or reconstructed samples.

[0463] In some embodiments, the codec tools used for the video unit are used to derive the predicted samples of the template. Alternatively, modified codec tools are used to derive the predicted samples of the template.

[0464] In some embodiments, the same motion vector (MV) as the video unit is used. In some embodiments, if the MV is a fraction, the MV is rounded to integer precision.

[0465] In some embodiments, the same block vector (BV) as the video unit is used. In some embodiments, if the BV is a fraction, the BV is rounded to integer precision.

[0466] In some embodiments, the same intra-frame prediction scheme as the video unit is used. In some embodiments, filters are used for multiple codec tools.

[0467] In some embodiments, one or more parameters of the filter are predefined. Alternatively, one or more parameters of the filter are transmitted via a signal.

[0468] In some embodiments, multiple filters are applied. In some embodiments, a second filter is applied to the filtering result of the first filter.

[0469] In some embodiments, multiple predicted signals are used in the filter. In some embodiments, all predicted signals are used directly in the filter. In some embodiments, which predicted signals are used in the filter is determined by signal transmission or derivation. In some embodiments, at least two predicted signals are first combined before being used in the filter.

[0470] In some embodiments, multiple predicted signals are divided into subgroups, and which subgroup is used in the filter is determined by signal transmission or derivation. In some embodiments, whether and / or how the multiple predicted signals are divided depends on the encoding / decoding information.

[0471] In some embodiments, whether and / or how filters are applied to video units depends on encoding / decoding information. In some embodiments, encoding / decoding information includes at least one of the following: whether an encoding / decoding method is permitted, block dimension, block size, block depth, stripe type, picture type, segmentation tree type, temporal layer identifier, block location, color format, or color components.

[0472] In some embodiments, the filter is applied to all color components. In some embodiments, if the filter is applied to the chroma component, the filter is different from the filter applied to the luminance component.

[0473] In some embodiments, whether a filter is applied to a first component and / or the manner in which a filter is applied to a first component depends on whether a filter is applied to a second component. In some embodiments, the first component includes a chromaticity component, and the second component includes a luminance component.

[0474] In some embodiments, the filter is applied to the first component in the same way as it is applied to the second component. In some other embodiments, the filter is applied to the first component in a different way than it is applied to the second component.

[0475] In some embodiments, the filter is applied to the luminance component but not to the chrominance component. In some embodiments, the luminance component includes Y in the YCbCr color space or green (G) in the RGB color space. In some embodiments, the chrominance component includes at least one of Cb or Cr in the YCbCr color space, or the chrominance component includes at least one of R or B in the RGB color space.

[0476] In some embodiments, whether the current block is encoded or decoded using a filter is transmitted via signaling using one or more syntax elements. In some embodiments, one or more syntax elements are binary-coded into one of the following: a flag, a fixed-length code, an EG(x) code, a unary code, a rounded unary code, or a rounded binary code. In some embodiments, one or more syntax elements are context-coded or decoded. Alternatively, one or more syntax elements are bypass-coded or decoded.

[0477] In some embodiments, the context depends on the encoded / decoded information. In some embodiments, the encoded / decoded information includes at least one of the following: block dimension, block size, stripe type, image type, information about neighboring blocks, information about other encoding / decoding tools used for the current block, or information about the temporal layer.

[0478] In some embodiments, one or more syntax elements are indicated at one of the following: sequence header, picture header, sequence parameter set (SPS), video parameter set (VPS), dependency parameter set (DPS), decoding capability information (DCI), picture parameter set (PPS), adaptive parameter set (APS), strip header, or slice header. In some embodiments, one or more syntax elements are encoded and decoded predictively. In some embodiments, one or more syntax elements are predicted from one or more syntax elements of neighboring blocks.

[0479] In some embodiments, the filter indication is transmitted via a signal based on conditions. In some embodiments, the conditions include at least one of the following: block dimension, block size, block depth, stripe type, image type, segmentation tree type, temporal layer identifier, block location, color format, or color components.

[0480] In some embodiments, a video unit includes at least one of the following: color components, prediction blocks (PB), transform blocks (TB), codec blocks (CB), prediction units (PU), transform units (TU), codec tree blocks (CTB), codec units (CU), codec tree units (CTU), CTU rows, CTU groups, stripes, slices, sub-pictures, blocks, sub-regions within blocks, or regions containing more than one sample point or pixel.

[0481] In some embodiments, an indication of whether and / or how to perform refinement of a video unit by applying filters is given at one of the following: sequence level, picture group level, picture level, strip level, or slice group level. In some embodiments, an indication of whether and / or how to perform refinement of a video unit by applying filters is given at one of the following: sequence header, picture header, sequence parameter set (SPS), video parameter set (VPS), dependency parameter set (DPS), decoding capability information (DCI), picture parameter set (PPS), adaptive parameter set (APS), strip header, or slice group header.

[0482] In some embodiments, method 5500 further includes: determining whether and / or how to perform refinement of video units by applying filters based on at least one of the following: messages indicated in one of the following: DPS, SPS, VPS, PPS, APS, picture header, strip header, slice header, maximum codec unit (LCU), codec unit (CU), LCU line, LCU group, TU, PU block, video codec unit; the position of one of the following: CU, PU, ​​TU, block, video codec unit; the block dimension of the current block and / or the neighboring blocks of the current block; the block shape of the current block and / or the neighboring blocks of the current block; the codec mode of the video unit; an indication of the color format; the codec tree structure; strip type; slice type; picture type; color components; temporal layer identifier; standard grade or level or layer.

[0483] In some embodiments, syntax elements are binary-coded into one of the following: a flag, a fixed-length code, an EG(x) code, a unary code, a rounded unary code, or a rounded binary code. In some embodiments, syntax elements are encoded and decoded using at least one context model. Alternatively, syntax elements are bypassed and encoded / decoded.

[0484] In some embodiments, syntax elements are transmitted via signaling based on conditions. In some embodiments, syntax elements are transmitted via signaling only if the corresponding function applies. Alternatively, syntax elements are transmitted via signaling if the dimension of the video unit satisfies a condition.

[0485] In some embodiments, syntax elements are signaled at one of the following levels: block level, sequence level, picture group level, picture level, stripe level, or slice group level. In some embodiments, syntax elements are signaled in one of the following codec structures: CTU, CT, TU, PU, ​​CTB, CB, TB, or PB; sequence header; picture header; sequence parameter set (SPS); video parameter set (VPS); dependency parameter set (DPS); decoding capability information (DCI); picture parameter set (PPS); adaptive parameter set (APS); stripe header; or slice group header.

[0486] In some embodiments, another codec tool is also applied to the video unit. Alternatively, the other codec tool is excluded for the video unit. In some embodiments, the other codec tool includes at least one of the following: affine, multiple transform selection (MTS), low-frequency inseparable transform (LFNST), Merge mode with motion vector difference (MMVD), MIP, ISP, CCLM, CCCM, symmetric motion vector difference (SMVD), bidirectional optical flow (BDOF), DMVR, history-based motion vector prediction (HMVP), template matching, IBC, or palette.

[0487] In some embodiments, if refinement is performed by applying a filter, another codec tool is implicitly disabled without signaling. In some other embodiments, if another codec tool is used, refinement performed by applying a filter is implicitly disabled without signaling.

[0488] According to another embodiment of this disclosure, a non-transitory computer-readable recording medium is provided. This non-transitory computer-readable recording medium stores a bitstream of video generated by a method performed by means of a video processing apparatus. The method includes: refining a prediction or reconstruction of video cells by applying filters to video cells of the video; and generating a bitstream based on the refined prediction or refined reconstruction.

[0489] According to further embodiments of this disclosure, a method for storing a bitstream of video is provided. The method includes: refining a prediction or reconstruction of video cells by applying filters to video cells of the video; generating a bitstream based on the refined prediction or refined reconstruction; and storing the bitstream in a non-transitory computer-readable recording medium.

[0490] The embodiments of this disclosure can be described according to the following entries, and their features can be combined in any reasonable manner.

[0491] Item 1. A method for video processing, comprising: conversion between video units of a video and bitstreams of the video units; refining a prediction or reconstruction of the video units by applying a filter to the video units; and performing the conversion based on the refined prediction or the refined reconstruction.

[0492] Item 2. The method according to Item 1, wherein the filter is used for one or more intra-frame codec tools.

[0493] Item 3. The method according to Item 2, wherein the one or more intra-frame encoding / decoding tools include at least one of the following: regular intra-frame prediction, a variant of regular intra-frame prediction, decoder-side intra-frame mode derivation (DIMD), a variant of DIMD, template-based intra-frame mode derivation (TIMD), a variant of TIMD, multiple reference lines (MRL), a variant of MRL, intra-frame sub-segmentation (ISP), a variant of ISP, matrix-weighted intra-frame prediction (MIP), a variant of MIP, IntraTMP, a variant of IntraTMP, intra-frame prediction fusion, a variant of intra-frame prediction fusion, spatial geometry segmentation mode (SGPM), a variant of SGPM, template-based multi-reference line intra-frame prediction (TMRL), a variant of TMRL, position-dependent intra-frame prediction combination (PDPC), a variant of PDPC, gradient PDPC, a variant of gradient PDPC, cross-component linear model (CCLM), a variant of CCLM, multi-model CCLM (MMLM), a variant of MMLM, convolutional cross-component model (CCCM), a variant of CCCM, gradient linear model (GLM), a variant of GLM, chroma fusion, or a variant of chroma fusion.

[0494] Item 4. The method according to Item 1, wherein the filter is used for one or more inter-frame encoding / decoding tools.

[0495] Item 5. The method according to Item 4, wherein the one or more inter-frame coding / decoding tools comprise at least one of the following: Intra-Inter-Frame Joint Prediction (CIIP), a variant of CIIP, Bidirectional Prediction (BCW) weighted at the codec unit (CU) level, a variant of BCW, Merge Mode with Motion Vector Difference (MMVD), a variant of MMVD, Template Matching (TM), a variant of TM, Affine, a variant of Affine, Decoder-Side Motion Vector Refinement (DMVR), a variant of DMVR, Multi-pass DMVR, a variant of Multi-pass DMVR, Prediction Refinement using Optical Flow (… PROF), PROF variants, Bidirectional Optical Flow (BDOF), BDOF variants, Sample-based BDOF, Sample-based BDOF variants, Adaptive Decoder-Side Motion Vector Refinement (ADMVR), ADMVR variants, Overlapping Block Motion Compensation (OBMC), OBMC variants, TM-based OBMC, TM-based OBMC variants, Multiple Hypothesis Prediction (MHP), MHP variants, Geometric Segmentation Mode (GPM), GPM variants, Bilateral Matching (BM) Advanced Motion Vector Prediction (AMVP) - Merge Mode, BM AMVP-Merge Mode variants, TM AMVP-Merge Mode or TM AMVP-Merge Mode variants.

[0496] Item 6. The method according to Item 5, wherein the CIIP comprises at least one of the following: CIIP-plane, CIIP-TIMD, or CIIP-TM, and / or wherein the BCE comprises a BCE index derived by TM, and / or wherein the MMVD comprises a TM-based reordering for the MMVD, and / or wherein the affine comprises an affine-MMVD or a TM-based reordering for the affine MMVD, and / or wherein the GPM comprises at least one of the following: GPM, GPM-TM, GPM-MMVD, or GPM-intraframe.

[0497] Item 7. The method according to Item 1, wherein the filter is used for one or more intra-block copy (IBC) codecs.

[0498] Item 8. The method according to Item 7, wherein the one or more IBC codec tools include at least one of the following: IBC AMVP mode, IBC Merge mode, IBC-CIIP mode, IBC-GPM mode, IBC Local Illumination (IBC-LIC) mode, or subpixel-based IBC mode.

[0499] Item 9. The method according to Item 8, wherein the IBC AMVP mode includes at least one of the following: normal IBC AMVP mode, TM-based IBC AMVP mode, reconstruction reordering (RR)-IBC AMVP mode, or other IBC AMVP mode wherein block vector (BV) predictions are derived and block vector difference (BVD) is transmitted or derived by signal transmission, and / or wherein the IBC Merge mode includes at least one of the following: normal IBC Merge mode, IBC-TM Merge mode, or IBC Merge mode with block vector difference (IBC-MBVD).

[0500] Item 10. The method according to Item 1, wherein the filter is used in other codec tools.

[0501] Item 11. The method according to Item 10, wherein the other encoding / decoding tool includes a palette or block-based differential pulse code modulation (BDPCM).

[0502] Item 12. The method according to Item 1, wherein at least one predicted sample or reconstructed sample is refined by the filter.

[0503] Item 13. The method according to Item 12, wherein a right shift operation is used after the filter, and / or wherein a limiting operation is used after the filter.

[0504] Item 14. According to the method of Item 12, one or more neighboring reconstructed samples of the video unit are used in the filter.

[0505] Item 15. The method according to Item 12, wherein one or more neighboring predicted samples of the current predicted sample are used in the filter.

[0506] Item 16. The method according to Item 15, wherein the one or more neighboring predicted samples are in at least one of the following directions: horizontal, vertical, 45 degrees or 135 degrees.

[0507] Item 17. The method according to Item 15, wherein the one or more neighboring predicted samples are of one of the following shapes: cross-shaped, rhomboid, or square-shaped.

[0508] Item 18. The method according to Item 15, wherein gradient information of the one or more neighboring predicted samples is used.

[0509] Item 19. The method according to Item 12, wherein the filter is a function having a linear form.

[0510] Item 20. The method according to Item 19, wherein the filter is P' = a P + b, where P represents the predicted signal / sample, P' represents the refined predicted signal / sample, and a and b represent the filter parameters.

[0511] Item 21. The method according to Item 12, wherein the filter is a function having a nonlinear form.

[0512] Item 22. The method according to Item 21, wherein the filter is P' = a P + b P^2 + c, where P represents the predicted signal / sample, P' represents the refined predicted signal / sample, and a, b, and c represent the filter parameters.

[0513] Item 23. The method according to Item 21, wherein the filter is P' = a P + b P P1+c, where P represents the first predicted signal / sample, P1 represents the second predicted signal / sample, P' represents the refined predicted signal / sample, and a, b, and c represent filter parameters.

[0514] Item 24. The method according to Item 12, wherein the input values ​​of the filter are predicted samples or reconstructed samples.

[0515] Item 25. The method according to Item 24, wherein whether the input value is a predicted sample or a reconstructed sample depends on the location of the sample to be filtered.

[0516] Item 26. The method according to Item 12, wherein the input value of the filter is a filled sample.

[0517] Item 27. The method according to Item 26, wherein whether the input value is a filled sample depends on the location of the sample to be filtered.

[0518] Item 28. The method according to Item 12, wherein positioning or location information is used in the filter.

[0519] Item 29. The method according to Item 28, wherein the horizontal and / or vertical distance between the current sample and the upper left position of the video unit is used in the filter, and / or wherein the horizontal and / or vertical distance between the current sample and the left boundary position of the video unit is used in the filter, and / or wherein the horizontal and / or vertical distance between the current sample and the upper boundary position of the video unit is used in the filter.

[0520] Item 30. According to the method described in Item 1, one or more parameters of the filter are derived.

[0521] Item 31. The method according to Item 30, wherein a template of neighboring samples is used to derive the one or more parameters.

[0522] Item 32. The method according to Item 31, wherein an upper template is used, and / or a left template is used, and / or a lower left template is used, and / or an upper right template is used, and / or an upper left template is used, and / or more than one of the upper, left, upper right, lower left, or upper left templates is combined into a template used in the filter, and / or an L-shaped template is used, and / or non-adjacent templates are used.

[0523] Item 33. The method according to Item 30, wherein multiple templates are used to derive the one or more parameters.

[0524] Item 34. The method according to Item 33, wherein a predetermined number of templates are used to derive the one or more parameters.

[0525] Item 35. The method according to Item 34, wherein the predetermined number is 3, and the upper template or a combination template using the upper template, the left template or a combination template using the left template, and the L-shaped template are used; or wherein the predetermined number is 3, and the upper template or a combination template using the upper template, the left template or a combination template using the left template, and the combination template using the upper template and the left template are used; or wherein the predetermined number is 2, and the upper template or a combination template using the upper template, and the left template or a combination template using the left template are used.

[0526] Item 36. The method according to Item 34, wherein which template is used to derive the one or more parameters being transmitted or derived by signaling.

[0527] Item 37. The method according to Item 30, wherein a scheme is applied to derive the one or more parameters using the set of training samples by minimizing the difference between the true value and the prediction of the set of training samples.

[0528] Item 38. The method according to Item 37, wherein gradient information or position information is used to derive the one or more parameters.

[0529] Item 39. The method according to Item 37, wherein the least mean square (LMS) scheme is used to derive the one or more parameters, and / or wherein the LDL scheme is used to derive the one or more parameters, and / or wherein Gaussian elimination is used to derive the one or more parameters.

[0530] Item 40. The method according to Item 37, wherein the difference includes at least one of the following: absolute transform difference (SATD), sum of squares of error (SSE), sum of absolute differences (SAD), or mean-reduced sum of absolute differences (MRSAD), or subjective quality measure.

[0531] Item 41. The method according to Item 40, wherein the subjective quality metric is a structural similarity index (SSIM) measurement.

[0532] Item 42. The method according to Item 37, wherein the difference is calculated in the form of D + lambda × R, where D represents a measure of distortion, R represents the number of bits considered, and lambda is a predefined factor or an on-the-fly derived factor.

[0533] Item 43. The method according to Item 37, wherein the truth value includes a reconstruction of the template, and the prediction includes one or more prediction signals of the template.

[0534] Item 44. The method according to Item 37, wherein the set of training samples includes all samples of the template, and / or wherein the set of training samples includes at least one sample of the template.

[0535] Item 45. The method according to Item 37, wherein an alternative scheme for solving the weighted parameters by minimizing the difference between the true value and the prediction is used, and / or wherein said alternative scheme includes a neural network.

[0536] Item 46. The method according to Item 30, wherein one or more neighboring samples of the video unit are used to derive the one or more parameters.

[0537] Item 47. The method according to Item 46, wherein the one or more neighboring samples include at least one of the following: a left neighboring sample of the video unit, an upper neighboring sample of the video unit, a lower left neighboring sample of the video unit, an upper left neighboring sample of the video unit, or an upper right neighboring sample of the video unit.

[0538] Item 48. The method according to Item 46, wherein the one or more neighboring samples are adjacent and / or non-adjacent.

[0539] Item 49. The method according to Item 46, wherein the one or more neighboring samples are predicted samples and / or reconstructed samples.

[0540] Item 50. The method according to Item 30, wherein the codec tool used for the video unit is used to derive the predicted samples of the template, or wherein a modified codec tool is used to derive the predicted samples of the template.

[0541] Item 51. The method according to Item 50, wherein the same motion vector (MV) as the video unit is used.

[0542] Item 52. The method according to Item 51, wherein if the MV is a fraction, the MV is rounded to integer precision.

[0543] Item 53. The method according to Item 50, wherein the same block vector (BV) as the video unit is used.

[0544] Item 54. The method according to Item 53, wherein if the BV is a fraction, the BV is rounded to integer precision.

[0545] Item 55. The method according to Item 50, wherein the same intra-frame prediction scheme as the video unit is used.

[0546] Item 56. The method according to Item 1, wherein the filter is used in multiple codec tools.

[0547] Item 57. The method according to Item 1, wherein one or more parameters of the filter are predefined, or wherein one or more parameters of the filter are transmitted via a signal.

[0548] Item 58. The method according to any one of items 1 to 57, wherein multiple filters are applied.

[0549] Item 59. The method according to Item 58, wherein the second filter is applied to the filtering result of the first filter.

[0550] Item 60. The method according to any one of items 1 to 59, wherein multiple predicted signals are used in the filter.

[0551] Item 61. The method according to Item 60, wherein all predicted signals are used directly in the filter.

[0552] Item 62. The method according to Item 60, wherein which predicted signals are used in the filter are transmitted by signal transmission or derived.

[0553] Item 63. The method according to Item 60, wherein at least two predicted signals are first combined before being used in the filter.

[0554] Item 64. The method according to Item 60, wherein the plurality of predicted signals are divided into subgroups, and which subgroup is used in the filter is determined by signal transmission or derivation.

[0555] Item 65. The method according to Item 64, wherein whether and / or how the plurality of prediction signals are divided depends on the encoding / decoding information.

[0556] Item 66. The method according to any one of items 1 to 65, wherein whether the filter is applied to the video unit and / or the manner in which the filter is applied to the video unit depends on the encoding / decoding information.

[0557] Item 67. The method according to Item 66, wherein the encoding / decoding information includes at least one of the following: whether the encoding / decoding method is allowed, block dimension, block size, block depth, stripe type, picture type, segmentation tree type, temporal layer identifier, block location, color format, or color components.

[0558] Item 68. The method according to Item 67, wherein the filter is applied to all color components.

[0559] Item 69. The method according to Item 67, wherein if the filter is applied to the chroma component, the filter is different from the filter for the luminance component.

[0560] Item 70. The method according to Item 67, wherein whether the filter is applied to the first component and / or the manner in which the filter is applied to the first component depends on whether the filter is applied to the second component.

[0561] Item 71. The method according to Item 70, wherein the first component includes a chromaticity component and the second component includes a luminance component.

[0562] Item 72. The method according to Item 70, wherein the filter is applied to the first component in the same manner as it is applied to the second component.

[0563] Item 73. The method according to Item 70, wherein the filter is applied to the first component in a manner different from that applied to the second component.

[0564] Item 74. The method according to Item 67, wherein the filter is applied to the luminance component but not to the chrominance component.

[0565] Item 75. The method according to Item 74, wherein the luminance component comprises Y in the YCbCr color space or green (G) in the RGB color space.

[0566] Item 76. The method according to Item 74, wherein the chromaticity component comprises at least one of Cb or Cr in the YCbCr color space, or wherein the chromaticity component comprises at least one of R or B in the RGB color space.

[0567] Item 77. The method according to any one of items 1 to 76, wherein whether the current block is applied to be encoded or decoded using the filter is transmitted via signaling using one or more syntax elements.

[0568] Item 78. According to the method described in Item 77, wherein the one or more syntax elements are binary-coded into one of the following: a flag, a fixed-length code, an EG(x) code, a unary code, a rounded unary code, or a rounded binary code.

[0569] Item 79. The method according to Item 77, wherein the one or more syntax elements are either context-encoded or bypass-encoded.

[0570] Item 80. The method according to Item 79, wherein the context depends on the encoded / decoded information.

[0571] Item 81. The method according to Item 80, wherein the encoded / decoded information includes at least one of the following: block dimension, block size, stripe type, picture type, information of neighboring blocks, information of other encoding / decoding tools used for the current block, or information of the temporal layer.

[0572] Item 82. According to the method described in Item 77, wherein one or more syntax elements are indicated at one of the following: sequence header, picture header, sequence parameter set (SPS), video parameter set (VPS), dependency parameter set (DPS), decoding capability information (DCI), picture parameter set (PPS), adaptive parameter set (APS), strip header, or slice header.

[0573] Item 83. The method according to Item 77, wherein the one or more syntax elements are encoded and decoded in a predictive manner.

[0574] Item 84. The method according to Item 77, wherein the one or more syntax elements are predicted by one or more syntax elements of neighboring blocks.

[0575] Item 85. The method according to any one of items 1 to 84, wherein the indication of the filter is transmitted via a signal based on conditions.

[0576] Item 86. The method according to Item 85, wherein the condition includes at least one of the following: block dimension, block size, block depth, stripe type, image type, segmentation tree type, temporal layer identifier, block location, color format, or color component.

[0577] Item 87. The method according to any one of items 1 to 86, wherein the video unit comprises at least one of the following: color component, prediction block (PB), transform block (TB), codec block (CB), prediction unit (PU), transform unit (TU), codec tree block (CTB), codec unit (CU), codec tree unit (CTU), CTU row, CTU group, strip, slice, sub-picture, block, sub-region within a block, or region containing more than one sample point or pixel.

[0578] Item 88. The method according to any one of items 1 to 87, wherein an indication of whether and / or how to perform the refinement of the video unit by applying the filter is indicated at one of the following: sequence level, picture group level, picture level, strip level, or slice group level.

[0579] Item 89. The method according to any one of items 1 to 87, wherein the indication of whether and / or how to perform the refinement of the video unit by applying the filter is indicated in one of the following: sequence header, picture header, sequence parameter set (SPS), video parameter set (VPS), dependency parameter set (DPS), decoding capability information (DCI), picture parameter set (PPS), adaptive parameter set (APS), strip header, or slice header.

[0580] Item 90. The method according to any one of items 1 to 89 further comprises: determining whether and / or how the refinement of the video unit is performed by applying the filter based on at least one of the following: a message indicated in one of the following: DPS, SPS, VPS, PPS, APS, picture header, strip header, slice header, maximum codec unit (LCU), codec unit (CU), LCU line, LCU group, TU, PU block, video codec unit; the position of one of the following: CU, PU, ​​TU, block, video codec unit; the block dimension of the current block and / or the neighboring blocks of the current block; the block shape of the current block and / or the neighboring blocks of the current block; the codec mode of the video unit; an indication of the color format; the codec tree structure; strip type; slice type; picture type; color components; temporal layer identifier; standard grade or level or layer.

[0581] Item 91. The method according to any one of items 1 to 90, wherein the syntax element is binary-coded as one of the following: a flag, a fixed-length code, an EG(x) code, a unary code, a rounded unary code, or a rounded binary code.

[0582] Item 92. The method according to any one of items 1 to 90, wherein the syntax element is encoded or decoded using at least one context model, or wherein the syntax element is encoded or decoded in a bypass manner.

[0583] Item 93. The method according to any one of items 1 to 90, wherein syntax elements are transmitted via signals based on conditions.

[0584] Item 94. The method according to Item 93, wherein the syntax element is transmitted via signal only when the corresponding function is applicable, or wherein the syntax element is transmitted via signal if the dimension of the video unit satisfies a condition.

[0585] Item 95. The method according to any one of items 1 to 90, wherein syntax elements are transmitted by signaling at one of the following levels: block level, sequence level, picture group level, picture level, strip level, or slice group level.

[0586] Item 96. The method according to Item 95, wherein the syntax element is transmitted via signaling in one of the following encoding / decoding structures: CTU, CT, TU, PU, ​​CTB, CB, TB or PB, sequence header, picture header, sequence parameter set (SPS), video parameter set (VPS), dependency parameter set (DPS), decoding capability information (DCI), picture parameter set (PPS), adaptive parameter set (APS), strip header, or slice header.

[0587] Item 97. The method according to any one of items 1 to 96, wherein another codec tool is also applied to the video unit, or wherein another codec tool is excluded for the video unit.

[0588] Item 98. The method according to Item 97, wherein the other encoding / decoding tool comprises at least one of the following: affine, multiple transform selection (MTS), low-frequency inseparable transform (LFNST), Merge mode with motion vector difference (MMVD), MIP, ISP, CCLM, CCCM, symmetric motion vector difference (SMVD), bidirectional optical flow (BDOF), DMVR, history-based motion vector prediction (HMVP), template matching, IBC, or palette.

[0589] Item 99. The method according to Item 97, wherein if the refinement is performed by applying the filter, the other codec tool is implicitly disabled without signaling.

[0590] Item 100. The method according to Item 97, wherein if the other codec tool is used, the refinement performed by applying the filter is implicitly disabled without signaling.

[0591] Item 101. The method according to any one of items 1 to 100, wherein the conversion includes encoding the video unit into the bitstream.

[0592] Item 102. The method according to any one of items 1 to 100, wherein the conversion includes decoding the video unit from the bitstream.

[0593] Item 103. An apparatus for video processing, comprising a processor and a nontransitory memory having instructions thereon, wherein the instructions, when executed by the processor, cause the processor to perform a method according to any one of items 1 to 102.

[0594] Item 104. A non-transitory computer-readable storage medium storing instructions that cause a processor to perform the method according to any one of items 1 to 102.

[0595] Item 105. A non-transitory computer-readable recording medium storing a bitstream of video generated by a method performed by means of a device for video processing, wherein the method includes: refining a prediction or reconstruction of the video cells by applying a filter to the video cells; and generating the bitstream based on the refined prediction or the refined reconstruction.

[0596] Item 106. A method for storing a bitstream of video, comprising: refining a prediction or reconstruction of a video cell by applying a filter to the video cell; generating the bitstream based on the refined prediction or the refined reconstruction; and storing the bitstream in a non-transitory computer-readable recording medium.

[0597] Example device Figure 56A block diagram of a computing device 5600 in which various embodiments of the present disclosure may be implemented is shown. The computing device 5600 may be implemented as a source device 110 (or video encoder 114 or 200) or a destination device 120 (or video decoder 124 or 300), or may be included in a source device 110 (or video encoder 114 or 200) or a destination device 120 (or video decoder 124 or 300).

[0598] It should be understood that, Figure 56 The computing device 5600 shown is for illustrative purposes only and is not intended to imply any limitation on the functionality and scope of the embodiments of this disclosure.

[0599] like Figure 56 As shown, computing device 5600 includes general-purpose computing device 5600. Computing device 5600 may include at least one or more processors or processing units 5610, memory 5620, storage unit 5630, one or more communication units 5640, one or more input devices 5650, and one or more output devices 5660.

[0600] In some embodiments, the computing device 5600 can be implemented as any user terminal or server terminal with computing capabilities. The server terminal can be a server provided by a service provider, a large computing device, etc. The user terminal can be, for example, any type of mobile terminal, fixed terminal, or portable terminal, including mobile phones, stations, units, devices, multimedia computers, multimedia tablet computers, internet nodes, communicators, desktop computers, laptop computers, notebook computers, netbook computers, tablet computers, personal communication system (PCS) devices, personal navigation devices, personal digital assistants (PDAs), audio / video players, digital cameras / camcorders, positioning devices, television receivers, radio receivers, e-book devices, gaming devices, or any combination thereof, and includes accessories and peripherals of these devices, or any combination thereof. It is conceivable that the computing device 5600 can support any type of interface to the user (such as "wearable" circuitry devices, etc.).

[0601] Processing unit 5610 can be a physical processor or a virtual processor, and can perform various processes based on programs stored in memory 5620. In a multiprocessor system, multiple processing units execute computer-executable instructions in parallel to improve the parallel processing capabilities of computing device 5600. Processing unit 5610 may also be referred to as a central processing unit (CPU), microprocessor, controller, or microcontroller.

[0602] Computing device 5600 typically includes various computer storage media. Such media can be any media accessible by computing device 5600, including but not limited to volatile and non-volatile media, or removable and non-removable media. Memory 5620 can be volatile memory (e.g., registers, cache, random access memory (RAM)), non-volatile memory (such as read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), or flash memory) or any combination thereof. Storage cell 5630 can be any removable or non-removable media and may include machine-readable media, such as memory, flash drives, disks, or other media that can be used to store information and / or data and can be accessed within computing device 5600.

[0603] The computing device 5600 may also include additional removable / non-removable storage media, volatile / non-volatile storage media. Although in Figure 56 Not shown, but may provide disk drives for reading from and / or writing to removable non-volatile disks, and optical disc drives for reading from and / or writing to removable non-volatile optical discs. In this case, each drive may be connected to a bus (not shown) via one or more data media interfaces.

[0604] Communication unit 5640 communicates with another computing device via a communication medium. Furthermore, the functionality of components in computing device 5600 can be implemented by a single computing cluster or by multiple computing machines communicating via communication connections. Therefore, computing device 5600 can operate in a networked environment using logical connections to one or more other servers, networked personal computers (PCs), or other general-purpose network nodes.

[0605] Input device 5650 can be one or more of various input devices, such as a mouse, keyboard, trackball, voice input device, etc. Output device 5660 can be one or more of various output devices, such as a monitor, speaker, printer, etc. With the aid of communication unit 5640, computing device 5600 can also communicate with one or more external devices (not shown), such as storage devices and display devices. Computing device 5600 can also communicate with one or more devices that enable a user to interact with computing device 5600, or any device that enables computing device 5600 to communicate with one or more other computing devices (e.g., network card, modem, etc.), if needed. Such communication can be performed via an input / output (I / O) interface (not shown).

[0606] In some embodiments, some or all components of computing device 5600 may be arranged in a cloud computing architecture, rather than integrated into a single device. In a cloud computing architecture, components may be provided remotely and work together to achieve the functionality described herein. In some embodiments, cloud computing provides computing, software, data access, and storage services without requiring end users to know the physical location or configuration of the systems or hardware providing these services. In various embodiments, cloud computing is provided via a wide area network (WAN) such as the Internet using suitable protocols. For example, a cloud computing provider provides applications via a WAN that can be accessed through a web browser or any other computing component. The software or components of the cloud computing architecture, along with the corresponding data, may be stored on servers at a remote location. Computing resources in a cloud computing environment may be consolidated or distributed at locations in remote data centers. Cloud computing infrastructure may be provided through shared data centers, although they may appear as a single access point for users. Therefore, cloud computing architectures can be used to provide the components and functionality described herein from service providers at remote locations. Alternatively, they may be provided from conventional servers or installed directly or otherwise on client devices.

[0607] In embodiments of this disclosure, computing device 5600 can be used to implement video encoding / decoding. Memory 5620 may include one or more video codec modules 5625 having one or more program instructions. These modules can be accessed and executed by processing unit 5610 to perform the functions of the various embodiments described herein.

[0608] In an example embodiment of performing video encoding, input device 5650 may receive video data as input 5670 to be encoded. The video data may be processed, for example, by video codec module 5625 to generate an encoded bitstream. The encoded bitstream may be provided as output 5680 via output device 5660.

[0609] In an example embodiment of performing video decoding, input device 5650 may receive an encoded bitstream as input 5670. The encoded bitstream may be processed, for example, by a video codec module 5625 to generate decoded video data. The decoded video data may be provided as output 5680 via output device 5660.

[0610] While this disclosure has been specifically shown and described with reference to preferred embodiments, those skilled in the art will understand that various changes in form and detail may be made without departing from the spirit and scope of this application as defined by the appended claims. These changes are intended to be covered by the scope of this application. Therefore, the foregoing description of embodiments of this application is not intended to be limiting.

Claims

1. A method for video processing, comprising: For the conversion between video units and bitstreams of the video units, the prediction or reconstruction of the video units is refined by applying filters to the video units; as well as The transformation is performed based on the refined prediction or the refined reconstruction.

2. The method of claim 1, wherein the filter is used in one or more intra-frame encoding / decoding tools.

3. The method of claim 2, wherein the one or more intra-frame encoding / decoding tools comprise at least one of the following: regular intra-frame prediction, a variant of regular intra-frame prediction, decoder-side intra-frame mode derivation (DIMD), a variant of DIMD, template-based intra-frame mode derivation (TIMD), a variant of TIMD, multiple reference lines (MRL), a variant of MRL, intra-frame sub-segmentation (ISP), a variant of ISP, matrix-weighted intra-frame prediction (MIP), a variant of MIP, IntraTMP, a variant of IntraTMP, intra-frame prediction fusion, a variant of intra-frame prediction fusion, spatial geometry segmentation mode (SGPM), a variant of SGPM, template-based multi-reference line intra-frame prediction (TMRL), a variant of TMRL, position-dependent intra-frame prediction combination (PDPC), a variant of PDPC, gradient PDPC, a variant of gradient PDPC, cross-component linear model (CCLM), a variant of CCLM, multi-model CCLM (MMLM), a variant of MMLM, convolutional cross-component model (CCCM), a variant of CCCM, gradient linear model (GLM), a variant of GLM, chroma fusion, or a variant of chroma fusion.

4. The method of claim 1, wherein the filter is used in one or more inter-frame encoding / decoding tools.

5. The method of claim 4, wherein the one or more inter-frame coding / decoding tools comprise at least one of the following: Intra-Inter-Frame Joint Prediction (CIIP), a variant of CIIP, Bidirectional Prediction (BCW) weighted at the codec unit (CU) level, a variant of BCW, Merge Mode with Motion Vector Difference (MMVD), a variant of MMVD, Template Matching (TM), a variant of TM, Affine, a variant of Affine, Decoder-Side Motion Vector Refinement (DMVR), a variant of DMVR, Multi-pass DMVR, a variant of Multi-pass DMVR, and Prediction Refinement Utilizing Optical Flow. (PROF), variants of PROF, bidirectional optical flow (BDOF), variants of BDOF, sample-based BDOF, variants of sample-based BDOF, adaptive decoder-side motion vector refinement (ADMVR), variants of ADMVR, overlapping block motion compensation (OBMC), variants of OBMC, TM-based OBMC, variants of TM-based OBMC, multiple hypothesis prediction (MHP), variants of MHP, geometric segmentation mode (GPM), variants of GPM, bilateral matching (BM) advanced motion vector prediction (AMVP)-Merge mode, variants of BM AMVP-Merge mode, TM AMVP-Merge mode or variants of TM AMVP-Merge mode.

6. The method of claim 5, wherein the CIIP comprises at least one of the following: CIIP-planar, CIIP-TIMD, or CIIP-TM, and / or The BCE includes a BCE index derived via TM, and / or The MMVD includes TM-based reordering for MMVD, and / or The affine includes affine-MMVD or TM-based reordering for affine MMVD, and / or The GPM includes at least one of the following: GPM, GPM-TM, GPM-MMVD, or GPM-intraframe.

7. The method of claim 1, wherein the filter is used in one or more intra-block copy (IBC) codecs.

8. The method of claim 7, wherein the one or more IBC codec tools include at least one of the following: IBC AMVP mode, IBC Merge mode, IBC-CIIP mode, IBC-GPM mode, IBC Local Illumination (IBC-LIC) mode, or subpixel-based IBC mode.

9. The method of claim 8, wherein the IBC AMVP mode comprises at least one of the following: a normal IBC AMVP mode, a TM-based IBC AMVP mode, a reconstruction-reordering (RR)-IBC AMVP mode, or other IBC AMVP modes wherein block vector (BV) predictions are derived and block vector difference (BVD) is transmitted or derived via signal transmission, and / or The IBC Merge mode includes at least one of the following: normal IBC Merge mode, IBC-TM Merge mode, or IBC Merge mode with block vector difference (IBC-MBVD).

10. The method of claim 1, wherein the filter is used in other encoding / decoding tools.

11. The method of claim 10, wherein the other encoding / decoding tool includes a palette or block-based differential pulse code modulation (BDPCM).

12. The method of claim 1, wherein at least one predicted sample or reconstructed sample is refined by the filter.

13. The method of claim 12, wherein a right shift operation is used after the filter, and / or The clipping operation is used after the filter.

14. The method of claim 12, wherein one or more neighboring reconstructed samples of the video unit are used in the filter.

15. The method of claim 12, wherein one or more neighboring predicted samples of the current predicted sample are used in the filter.

16. The method of claim 15, wherein the one or more neighboring predicted samples are in at least one of the following directions: horizontal, vertical, 45 degrees or 135 degrees.

17. The method of claim 15, wherein the one or more neighboring predicted samples are of one of the following shapes: cross-shaped, rhomboid, or square-shaped.

18. The method of claim 15, wherein gradient information of one or more neighboring predicted samples is used.

19. The method of claim 12, wherein the filter is a function having a linear form.

20. The method of claim 19, wherein the filter is P' = a P + b, where P represents the predicted signal / sample, P' represents the refined predicted signal / sample, and a and b represent the filter parameters.

21. The method of claim 12, wherein the filter is a function having a nonlinear form.

22. The method of claim 21, wherein the filter is P' = a P + b P^2 + c, where P represents the predicted signal / sample, P' represents the refined predicted signal / sample, and a, b, and c represent the filter parameters.

23. The method of claim 21, wherein the filter is P' = a P + b P P1+c, where P represents the first predicted signal / sample, P1 represents the second predicted signal / sample, P' represents the refined predicted signal / sample, and a, b, and c represent filter parameters.

24. The method of claim 12, wherein the input values ​​of the filter are predicted samples or reconstructed samples.

25. The method of claim 24, wherein whether the input value is a predicted sample or a reconstructed sample depends on the location of the sample to be filtered.

26. The method of claim 12, wherein the input value of the filter is a filled sample.

27. The method of claim 26, wherein whether the input value is a filled sample depends on the position of the sample to be filtered.

28. The method of claim 12, wherein the positioning or location information is used in the filter.

29. The method of claim 28, wherein the horizontal and / or vertical distance between the current sample point and the upper left position of the video unit is used in the filter, and / or The horizontal and / or vertical distance between the current sample point and the left boundary position of the video unit is used in the filter, and / or The horizontal and / or vertical distance between the current sample point and the upper boundary position of the video unit is used in the filter.

30. The method of claim 1, wherein one or more parameters of the filter are derived.

31. The method of claim 30, wherein a template of neighboring samples is used to derive the one or more parameters.

32. The method of claim 31, wherein the upper template is used, and / or The template on the left is used, and / or The bottom left template was used, and / or The upper right template was used, and / or The top-left template was used, and / or The top template, left template, top right template, bottom left template, or top left template are combined into a single template used in the filter, and / or L-shaped templates were used, and / or Non-adjacent templates are used.

33. The method of claim 30, wherein a plurality of templates are used to derive the one or more parameters.

34. The method of claim 33, wherein a predetermined number of templates are used to derive the one or more parameters.

35. The method of claim 34, wherein the predetermined number is 3, and the upper template or a combination template using the upper template, the left template or a combination template using the left template, and the L-shaped template are used, or The predetermined number is 3, and the upper template or a combination template using the upper template, the left template or a combination template using the left template, and a combination template using both the upper template and the left template are used, or The predetermined number is 2, and the upper template or a combination template using the upper template and the left template or a combination template using the left template are used.

36. The method of claim 34, wherein the template used to derive the one or more parameters is transmitted or derived via signal transmission.

37. The method of claim 30, wherein a scheme is applied to derive the one or more parameters using the set of training samples by minimizing the difference between the true value and the prediction of the set of training samples.

38. The method of claim 37, wherein gradient information or position information is used to derive the one or more parameters.

39. The method of claim 37, wherein the least mean square (LMS) scheme is used to derive the one or more parameters, and / or The LDL scheme is used to derive one or more parameters, and / or Gaussian elimination is used to derive one or more of the parameters.

40. The method of claim 37, wherein the difference comprises at least one of: absolute transform difference (SATD), sum of squared errors (SSE), sum of absolute differences (SAD), or mean-reduced sum of absolute differences (MRSAD), or subjective quality measure.

41. The method of claim 40, wherein the subjective quality metric is a structural similarity index (SSIM) measurement.

42. The method of claim 37, wherein the difference is calculated in the form of D + lambda × R, where D represents a measure of distortion, R represents the number of bits considered, and lambda is a predefined factor or an on-the-fly derived factor.

43. The method of claim 37, wherein the true value comprises a reconstruction of the template, and the prediction comprises one or more prediction signals of the template.

44. The method of claim 37, wherein the set of training samples includes all samples of the template, and / or The set of training samples includes at least one sample of the template.

45. The method of claim 37, wherein another scheme for solving the weighting parameters by minimizing the difference between the true value and the prediction is used, and / or The other approach mentioned above includes neural networks.

46. ​​The method of claim 30, wherein one or more neighboring samples of the video unit are used to derive the one or more parameters.

47. The method of claim 46, wherein the one or more neighboring samples comprise at least one of the following: The left-side adjacent sample point of the video unit, The upper adjacent sample points of the video unit, The lower left neighboring sample point of the video unit, The upper left neighboring sample point of the video unit, or The upper right neighboring sample point of the video unit.

48. The method of claim 46, wherein the one or more neighboring samples are adjacent and / or non-adjacent.

49. The method of claim 46, wherein the one or more neighboring samples are predicted samples and / or reconstructed samples.

50. The method of claim 30, wherein the encoding / decoding tool used for the video unit is used to derive the predicted samples of the template, or The modified encoding and decoding tools were used to derive the predicted samples of the template.

51. The method of claim 50, wherein the same motion vector (MV) as the video unit is used.

52. The method of claim 51, wherein if the MV is a fraction, the MV is rounded to integer precision.

53. The method of claim 50, wherein the same block vector (BV) as the video unit is used.

54. The method of claim 53, wherein if the BV is a fraction, the BV is rounded to integer precision.

55. The method of claim 50, wherein the same intra-frame prediction scheme as the video unit is used.

56. The method of claim 1, wherein the filter is used in a plurality of codec tools.

57. The method of claim 1, wherein one or more parameters of the filter are predefined, or One or more parameters of the filter are transmitted via a signal.

58. The method according to any one of claims 1 to 57, wherein a plurality of filters are applied.

59. The method of claim 58, wherein the second filter is applied to the filtering result of the first filter.

60. The method according to any one of claims 1 to 59, wherein a plurality of predicted signals are used in the filter.

61. The method of claim 60, wherein all predicted signals are used directly in the filter.

62. The method of claim 60, wherein which predicted signals are used in the filter are transmitted by signal transmission or derived.

63. The method of claim 60, wherein at least two predicted signals are first combined before being used in the filter.

64. The method of claim 60, wherein the plurality of predicted signals are divided into subgroups, and which subgroup is used in the filter is determined by signal transmission or derivation.

65. The method of claim 64, wherein whether and / or how the plurality of prediction signals are divided depends on the encoding / decoding information.

66. The method according to any one of claims 1 to 65, wherein whether the filter is applied to the video unit and / or the manner in which the filter is applied to the video unit depends on the encoding / decoding information.

67. The method of claim 66, wherein the encoding / decoding information comprises at least one of the following: Are encoding / decoding methods allowed? Block dimension Block size, Block depth, Strip type, Image type Segmentation tree type, Temporal layer identifier, Block position, Color format, or Color components.

68. The method of claim 67, wherein the filter is applied to all color components.

69. The method of claim 67, wherein if the filter is applied to the chroma component, the filter is different from the filter for the luminance component.

70. The method of claim 67, wherein whether the filter is applied to the first component and / or the manner in which the filter is applied to the first component depends on whether the filter is applied to the second component.

71. The method of claim 70, wherein the first component comprises a chromaticity component, and the second component comprises a luminance component.

72. The method of claim 70, wherein the filter is applied to the first component in the same manner as it is applied to the second component.

73. The method of claim 70, wherein the filter is applied to the first component in a different manner than it is applied to the second component.

74. The method of claim 67, wherein the filter is applied to the luminance component but not to the chrominance component.

75. The method of claim 74, wherein the luminance component comprises Y in the YCbCr color space or green (G) in the RGB color space.

76. The method of claim 74, wherein the chromaticity component comprises at least one of Cb or Cr in the YCbCr color space, or The chromaticity components mentioned above include at least one of R or B in the RGB color space.

77. The method according to any one of claims 1 to 76, wherein whether the current block is applied to be encoded or decoded using the filter is transmitted via signaling using one or more syntax elements.

78. The method of claim 77, wherein the one or more syntax elements are binary-coded into one of the following: a flag, a fixed-length code, an EG(x) code, a unary code, a rounded unary code, or a rounded binary code.

79. The method of claim 77, wherein the one or more syntax elements are context-encoded or decoded, or One or more of the syntax elements are bypassed for encoding and decoding.

80. The method of claim 79, wherein the context depends on the encoded / decoded information.

81. The method of claim 80, wherein the encoded / decoded information comprises at least one of the following: Block dimension Block size, Strip type, Image type Information about neighboring blocks Information from other codecs used in the current block, or Information from the time-domain layer.

82. The method of claim 77, wherein the one or more syntax elements are indicated at one of the following: Sequence header, Image header, Sequence Parameter Set (SPS) Video Parameter Set (VPS) Dependency Parameter Set (DPS) Decoding Capability Information (DCI) Image Parameter Set (PPS) Adaptive Parameter Set (APS) strip head, or The beginning of the film.

83. The method of claim 77, wherein the one or more syntax elements are encoded and decoded in a predictive manner.

84. The method of claim 77, wherein the one or more syntax elements are predicted by one or more syntax elements of neighboring blocks.

85. The method according to any one of claims 1 to 84, wherein the indication of the filter is transmitted via a signal based on conditions.

86. The method of claim 85, wherein the condition comprises at least one of the following: Block dimension Block size, Block depth, Strip type, Image type Segmentation tree type, Temporal layer identifier, Block positioning, Color format, or Color components.

87. The method according to any one of claims 1 to 86, wherein the video unit comprises at least one of the following: Color components, Predicted blocks (PB) Transform Block (TB) Code Block (CB) Prediction Unit (PU) Transformer Unit (TU) Code-decode tree block (CTB) Codec Unit (CU) Code-decode tree unit (CTU) CTU line, CTU group strips, piece, Sub-images piece, Sub-regions within a block, or A region containing more than one sample point or pixel.

88. The method according to any one of claims 1 to 87, wherein an indication of whether and / or how to perform the refinement of the video unit by applying the filter is indicated at one of the following: sequence level, Image group level, Image level, strip level, or Film series level.

89. The method according to any one of claims 1 to 87, wherein an indication of whether and / or how to perform the refinement of the video unit by applying the filter is indicated in one of the following: Sequence header, Image header, Sequence Parameter Set (SPS) Video Parameter Set (VPS) Dependency Parameter Set (DPS) Decoding Capability Information (DCI) Image Parameter Set (PPS) Adaptive Parameter Set (APS) strip head, or The beginning of the film.

90. The method according to any one of claims 1 to 89, further comprising: Determine whether and / or how to perform the refinement of the video unit by applying the filter based on at least one of the following: The message indicated in one of the following: DPS, SPS, VPS, PPS, APS, image header, strip header, slice header, maximum codec unit (LCU), codec unit (CU), LCU line, LCU group, TU, PU block, video codec unit. The following are the locations: CU, PU, ​​TU, block, video codec unit. The block dimensions of the current block and / or its neighboring blocks. The block shape of the current block and / or the blocks adjacent to the current block. The encoding and decoding mode of the video unit, Instructions for color format, Encoder tree structure, Strip type, Film set type, Image type, Color components, Temporal layer identifier, Standard grade, level, or tier.

91. The method according to any one of claims 1 to 90, wherein the syntax element is binary-coded as one of the following: a flag, a fixed-length code, an EG(x) code, a unary code, a rounded unary code, or a rounded binary code.

92. The method according to any one of claims 1 to 90, wherein the syntax elements are encoded and decoded using at least one context model, or The syntax elements therein are bypassed and encoded / decoded.

93. The method according to any one of claims 1 to 90, wherein syntax elements are transmitted via signals based on conditions.

94. The method of claim 93, wherein the syntax element is transmitted via signal only when the corresponding function is applicable, or If the dimension of the video unit meets the condition, the syntax element is transmitted via signal.

95. The method according to any one of claims 1 to 90, wherein the syntax element is transmitted via signal at one of the following locations: block level sequence level, Image group level, Image level, strip level, or Film series level.

96. The method of claim 95, wherein the syntax element is transmitted via a signal in one of the following ways: The following are encoding / decoding structures: CTU, CT, TU, PU, ​​CTB, CB, TB, or PB. Sequence header, Image header, Sequence Parameter Set (SPS) Video Parameter Set (VPS) Dependency Parameter Set (DPS) Decoding Capability Information (DCI) Image Parameter Set (PPS) Adaptive Parameter Set (APS) strip head, or The beginning of the film.

97. The method according to any one of claims 1 to 96, wherein another encoding / decoding tool is also applied to the video unit, or Another encoding / decoding tool was excluded for the video unit.

98. The method of claim 97, wherein the other encoding / decoding tool comprises at least one of the following: affine, multiple transform selection (MTS), low-frequency inseparable transform (LFNST), Merge mode with motion vector difference (MMVD), MIP, ISP, CCLM, CCCM, symmetric motion vector difference (SMVD), bidirectional optical flow (BDOF), DMVR, history-based motion vector prediction (HMVP), template matching, IBC, or palette.

99. The method of claim 97, wherein if the refinement is performed by applying the filter, the other codec tool is implicitly disabled without signaling.

100. The method of claim 97, wherein if the other codec tool is used, the refinement performed by applying the filter is implicitly disabled without signaling.

101. The method according to any one of claims 1 to 100, wherein the conversion comprises encoding the video unit into the bitstream.

102. The method according to any one of claims 1 to 100, wherein the conversion comprises decoding the video unit from the bitstream.

103. An apparatus for video processing, comprising a processor and a nontransitory memory having instructions thereon, wherein the instructions, when executed by the processor, cause the processor to perform the method according to any one of claims 1 to 102.

104. A non-transitory computer-readable storage medium storing instructions that cause a processor to perform the method according to any one of claims 1 to 102.

105. A non-transitory computer-readable recording medium storing a bitstream of video generated by a method performed by means of a video processing apparatus, wherein the method includes: The prediction or reconstruction of the video unit is refined by applying filters to the video unit of the video; as well as The bitstream is generated based on the refined prediction or the refined reconstruction.

106. A method for storing a bitstream of video, comprising: The prediction or reconstruction of the video unit is refined by applying filters to the video unit of the video; The bitstream is generated based on the refined prediction or the refined reconstruction; as well as The bitstream is stored in a non-transitory computer-readable recording medium.

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