Line buffer for in-loop filter in video coding

Abstract

A mechanism of processing video data is disclosed. The mechanism includes determining usage of side information in a loop filter by applying a line buffer restriction to the side information. The side information can include intermediate values from another filter. The conversion between the visual media data and the bitstream is performed based on the loop filter.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to International Patent Application No. PCT / CN2024 / 071841, filed on January 11, 2024. The aforementioned patent application is incorporated herein by reference in its entirety. Technical Field

[0003] This patent document relates to the generation, storage, and use of digital audio and video media information in file formats. Background Technology

[0004] Digital video consumes the largest bandwidth of the internet and other digital communication networks. As the number of connected user devices capable of receiving and displaying video increases, the bandwidth demand for digital video is likely to continue to grow. Summary of the Invention

[0005] The first aspect relates to a method for processing video data, comprising: determining the use of side information in a loop filter by applying line buffer constraints to the side information; and performing a conversion between visual media data and a bitstream based on the loop filter.

[0006] The second aspect relates to an apparatus for processing video data, comprising: a processor and a non-transitory memory having instructions thereon, wherein the instructions, when executed by the processor, cause the processor to perform any of the aforementioned aspects.

[0007] The third aspect relates to a non-transitory computer-readable medium including a computer program product for use by a video codec apparatus, the computer program product including computer-executable instructions stored on the non-transitory computer-readable medium, such that when executed by a processor, the video codec apparatus performs the methods of any of the preceding aspects.

[0008] The fourth aspect relates to a non-transitory computer-readable recording medium storing a bitstream of video generated by a method performed by a video processing apparatus, wherein the method includes: determining the use of side information in a loop filter by applying line buffer constraints to side information; and generating the bitstream based on the determination.

[0009] The fifth aspect relates to a method for storing a bitstream of video, comprising: determining the use of side information in a loop filter by applying line buffer constraints to the side information; generating a bitstream based on the determination; and storing the bitstream in a non-transitory computer-readable recording medium.

[0010] For clarity, any of the foregoing embodiments may be combined with any one or more other foregoing embodiments to create new embodiments within the scope of this disclosure.

[0011] These and other features will be more clearly understood through the following detailed description with reference to the accompanying drawings and claims. Attached Figure Description

[0012] To gain a more complete understanding of this disclosure, reference is now made to the following brief description, taken in conjunction with the accompanying drawings and detailed description, wherein like reference numerals denote like parts.

[0013] Figure 1 An example of the nominal vertical and horizontal positions of 4:2:2 luminance and chrominance samples in an image is shown.

[0014] Figure 2 A sample encoder block diagram is shown.

[0015] Figure 3 An example image is shown, segmented into raster scan strips.

[0016] Figure 4 An example image is shown, segmented into rectangular scan strips.

[0017] Figure 5 An example image showing the structure divided into bricks is shown.

[0018] Figures 6A-6C An example of a codec tree block (CTB) spanning image boundaries is shown.

[0019] Figure 7 An example of an intra-frame prediction mode is shown.

[0020] Figure 8 An example of a block boundary is shown in the image.

[0021] Figure 9 An example of pixels used in a filter is shown.

[0022] Figure 10 An example of the filter shape for an adaptive loop filter (ALF) is shown.

[0023] Figure 11 An example of the transform coefficients supported by a 5×5 diamond filter is shown.

[0024] Figure 12 An example of relative coordinates supported by a 5×5 rhombus filter is shown.

[0025] Figure 13 This is a block diagram illustrating an example video processing system.

[0026] Figure 14 This is a block diagram of an example video processing device.

[0027] Figure 15This is a flowchart of an example method for video processing.

[0028] Figure 16 This is a block diagram illustrating an example video codec system.

[0029] Figure 17 This is a block diagram showing an example encoder.

[0030] Figure 18 This is a block diagram showing an example decoder.

[0031] Figure 19 This is a schematic diagram of an example encoder.

[0032] Figure 20 This is a flowchart of another example method for video processing. Detailed Implementation

[0033] First, it should be understood that although illustrative implementations of one or more embodiments are provided below, the disclosed systems and / or methods can be implemented using any number of techniques, whether currently known or yet to be developed. This disclosure should not be limited in any way to the illustrative implementations, drawings, and techniques shown below, including the exemplary designs and implementations shown and described herein, but modifications can be made within the scope of the appended claims and their equivalents.

[0034] The use of chapter headings in this document is for ease of understanding and not to limit the applicability of the technologies and embodiments disclosed in each chapter to that chapter only. Furthermore, the technologies described herein are applicable to other video codec protocols and designs.

[0035] 1. Preliminary Discussion

[0036] This document relates to video codec technology. Specifically, it covers loop filters and other codec tools in image / video codecs. These ideas can be applied individually or in various combinations to video codecs, such as High Efficiency Video Codec (HEVC), Multi-Functional Video Codec (VVC), or other video codec technologies.

[0037] 2. Abbreviation

[0038] This disclosure includes the following abbreviations: Advanced Video Coding (ITU-T H.264 | ISO / IEC 14496-10) (AVC), Cocoded Picture Buffer (CPB), Pure Random Access (CRA), Codec Tree Unit (CTU), Coded Video Sequence (CVS), Decoded Picture Buffer (DPB), Decoded Parameter Set (DPS), General Constraint Information (GCI), High-Efficiency Video Coding, also known as ITU-T H.265 | ISO / IEC 23008-2 (HEVC), Joint Exploration Model (JEM), Motion Constraint Piece Set (MCTS), Network Abstraction Layer (NAL), Output Layer Set (OLS), Picture Header (PH), Picture Parameter Set (PPS), Grade, Layer and Level (PTL), Picture Unit (PU), Reference Picture Resampling (RPR), Raw Byte Sequence Payload (RBSP), Supplementary Enhancement Information (SEI), Strip Header (SH), Sequence Parameter Set (SPS), Video Coding Layer (VCL), Video Parameter Set (VPS), Multifunctional Video Coding, also known as ITU-T H.265 (HEVC). H.266 | ISO / IEC 23090-3 (VVC), VVC Test Model (VTM), Video Availability Information (VUI), Transform Unit (TU), Codec Unit (CU), Deblocking Filter (DF), Sample Adaptive Compensation (SAO), Adaptive Loop Filter (ALF), Codec Block Flag (CBF), Quantization Parameter (QP), Rate Distortion Optimization (RDO), Bilateral Filter (BF).

[0039] 3. Video codec standards

[0040] Video coding standards have evolved primarily through the development of standards by ITU-T and the International Organization for Standardization (ISO) / International Electrotechnical Commission (IEC). ITU-T developed the H.261 and H.263 standards, ISO / IEC developed the Moving Picture Experts Group (MPEG)-1 and MPEG-4 Vision, and the two organizations jointly developed the H.262 / MPEG-2 video standard and the H.264 / MPEG-4 Advanced Video Coding (AVC) standard and the H.265 / HEVC standard[1]. Starting with H.262, video coding standards are based on a hybrid video coding architecture, which utilizes temporal prediction plus transform coding. In order to explore future video coding technologies beyond HEVC, the Joint Video Exploration Team (JVET) was jointly established by the Video Coding Experts Group (VCEG) and MPEG. JVET adopted many methods and incorporated them into a reference software called the Joint Exploration Model (JEM)[2]. When the Multifunctional Video Coding (VVC) project was officially launched, JVET was renamed the Joint Video Experts Group (JVET). VVC is a codec standard that aims to reduce the bit rate by 50% compared to HEVC. The VVC working draft and VVC Test Model (VTM) are constantly being updated.

[0041] A sample version of the VVC draft, namely the Multi-Functional Video Codec (Draft 10), can be found at: https: / / jvet-experts.org / doc_end_user / documents / 19_Teleconference / wg11 / JVET-S2001-v17.zip. A sample version of the VVC reference software, named VTM, can be found at: https: / / vcgit.hhi.fraunhofer.de / jvet-u-ee2 / VVCSoftware_VTM / - / tree / VTM-11.2.

[0042] The International Telecommunication Union Telecommunication Standardization Sector (ITU-T) Video Coding Experts Group (VCEG) and the International Organization for Standardization and the International Electrotechnical Commission (ISO / IEC) Moving Picture Experts Group (MPEG) Joint Technical Committee (JTC) 1 / Subcommittee (SC) 29 / Working Group (WG) 11 are studying the potential need to standardize future video coding and decoding technologies with compression capabilities significantly exceeding the current VVC standard. This future standardization action could take the form of extended forms of VVC (multiple extensions) or entirely new standards. These groups are working together on 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. JVET has established the first exploratory experiment (EE), and reference software called the Enhanced Compression Model (ECM) is in use. The test model ECM is continuously being updated.

[0043] 3.1 Color Space and Chromaticity Downsampling

[0044] A color space, also known as a color model (or color system), is a mathematical model that describes a range of colors as tuples of numbers, such as 3 or 4 values ​​or color components (e.g., RGB). Generally, a color space is a refinement of a coordinate system and its subspaces. For video compression, the most commonly used color spaces are Luminance, Blue Difference, and Red Difference (YCbCr) and Red, Green, and Blue (RGB).

[0045] YCbCr, Y'CbCr, or Y Pb / Cb Pr / Cr, also written as YCBCR or Y'CBCR, is a family of color spaces used as part of the color image pipeline in video and digital photography systems. Y' is the luminance component, and CB and CR are the blue and red difference chromaticity components. Y' (with an apostrophe) is distinguished from Y, which is luminance, meaning that light intensity is non-linearly encoded based on gamma-corrected RGB primary colors.

[0046] Chromaticity downsampling is a practice of encoding images by applying a lower resolution to chromaticity information compared to luminance information, taking advantage of the fact that the human visual system is less sensitive to color differences than to luminance differences. 3.1.1 4:4:4

[0048] In a 4:4:4 scheme, each of the three Y'CbCr components has the same sampling rate. Therefore, there is no chromaticity downsampling. This scheme is sometimes used in high-end film scanners and film post-production. 3.1.2 4:2:2

[0050] In a 4:2:2 format, both chroma components are sampled at half the luminance sampling rate. The horizontal chroma resolution is halved, while the vertical chroma resolution remains unchanged. This reduces the bandwidth of the uncompressed video signal by one-third, with almost no visual difference. Figure 1 An example of the nominal vertical and horizontal positions of 4:2:2 luminance and chrominance samples in an image is shown. 3.1.3 4:2:0

[0052] In 4:2:0, the horizontal sampling is doubled compared to 4:1:1, but the vertical resolution is halved because the Cb and Cr channels are sampled only on each alternating row in this scheme, so the data rate is the same. Cb and Cr are downsampled by a factor of 2 in both the horizontal and vertical directions. There are three variations of the 4:2:0 scheme with different horizontal and vertical positions.

[0053] In MPEG-2, Cb and Cr are co-located horizontally. Cb and Cr are located between pixels vertically (at gap positions). In Joint Picture Experts Group (JPEG) / JPEG File Exchange Format (JFIF), H.261, and MPEG-1, Cb and Cr are located at gap positions, in the middle of alternating luminance samples. In 4:2:0 DV, Cb and Cr are co-located horizontally. Vertically, they are co-located on alternating lines.

[0054] Table 1. SubWidthC and SubHeightC values ​​derived from chroma_format_idc and separate_colour_plane_flag.

[0055]

[0056] 3.2 Example Encoding / Decoding Flow of Video Codec

[0057] Figure 2 An example encoder block diagram is shown, for example in VVC. The encoder contains 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 an offset and by applying a Finite Impulse Response (FIR) filter, respectively, and by utilizing the encoded and decoded side information through the signal transmission offset and filter coefficients. ALF is located in the final processing stage of each image and can be thought of as a tool to attempt to capture and repair artifacts caused by previous stages.

[0058] 3.3 Definition of Video / Encoding / Decoding Unit

[0059] An image is divided into one or more slice rows and one or more slice columns. A slice is a sequence of CTUs covering a rectangular area of ​​the image. A slice can be divided into one or more bricks, each brick comprising multiple CTU rows within the slice. A slice that is not divided into multiple bricks can also be called a brick. However, a brick that is a proper subset of a slice cannot be called a slice. A strip contains multiple slices of an image or multiple bricks of a slice.

[0060] Two stripe modes are supported: raster scan stripe mode and rectangular stripe mode. In raster scan stripe mode, the stripe contains a sequence of slices from a raster scan of the image. In rectangular stripe mode, the stripe contains multiple tiles that together form a rectangular area of ​​the image. The tiles within the rectangular stripe are arranged in the order of the stripe's raster scan. Figure 3 An example image segmented into raster scan strips is shown. In the example, the image is segmented according to raster scan strip segmentation, where the image includes 18×12 luminance CTUs and is divided into 12 patches and 3 raster scan strips.

[0061] Figure 4 Example images segmented into rectangular scan strips are shown. For example, Figure 4 An example of rectangular strip segmentation of an image with 18×12 luminance CTUs is shown, where the image is divided into 24 slices (6 slice columns and 4 slice rows) and 9 rectangular strips.

[0062] Figure 5 Example images showing the structure divided into bricks are shown. For example, Figure 5 An example of an image divided into slices, bricks, and rectangular strips is shown, where the image is divided into 4 slices (2 slice columns and 2 slice rows), 11 bricks (the top left slice contains 1 brick, the top right slice contains 5 bricks, the bottom left slice contains 2 bricks, and the bottom right slice contains 3 bricks) and 4 rectangular strips.

[0063] 3.3.1 CTU / CTB Dimensions

[0064] In VVC, the CTU size transmitted via signaling in the Sequence Parameter Set (SPS) by the syntax element log2_ctu_size_minus2 can be as small as 4×4.

[0065] 7.3.2.3 Sequence Parameter Set (RBSP) Syntax

[0066]

[0067]

[0068]

[0069] `log2_ctu_size_minus2` plus 2 specifies the luma codec block size for each CTU. `log2_min_luma_coding_block_size_minus2` plus 2 specifies the minimum luma codec block size. The variables `CtbLog2SizeY`, `CtbSizeY`, `MinCbLog2SizeY`, `MinCbSizeY`, `MinTbLog2SizeY`, `MaxTbLog2SizeY`, `MinTbSizeY`, `MaxTbSizeY`, `PicWidthInCtbsY`, `PicHeightInCtbsY`, `PicSizeInCtbsY`, `PicWidthInMinCbsY`, `PicHeightInMinCbsY`, `PicSizeInMinCbsY`, `PicSizeInSamplesY`, `PicWidthInSamplesC`, and `PicHeightInSamplesC` are derived as follows:

[0070] CtbLog2SizeY = log2_ctu_size_minus2 + 2 (7-9)

[0071] CtbSizeY = 1 << CtbLog2SizeY (7-10)

[0072] MinCbLog2SizeY = log2_min_luma_coding_block_size_minus2 + 2 (7-11)

[0073] MinCbSizeY = 1 << MinCbLog2SizeY (7-12)

[0074] MinTbLog2SizeY = 2 (7-13)

[0075] MaxTbLog2SizeY = 6 (7-14)

[0076] MinTbSizeY = 1 << MinTbLog2SizeY (7-15)

[0077] MaxTbSizeY = 1 << MaxTbLog2SizeY (7-16)

[0078] PicWidthInCtbsY = Ceil( pic_width_in_luma_samples ÷ CtbSizeY ) (7-17)

[0079] PicHeightInCtbsY = Ceil( pic_height_in_luma_samples ÷ CtbSizeY ) (7-18)

[0080] PicSizeInCtbsY = PicWidthInCtbsY PicHeightInCtbsY (7-19)

[0081] PicWidthInMinCbsY = pic_width_in_luma_samples / MinCbSizeY (7-20)

[0082] PicHeightInMinCbsY = pic_height_in_luma_samples / MinCbSizeY (7-21)

[0083] PicSizeInMinCbsY = PicWidthInMinCbsY PicHeightInMinCbsY (7-22)

[0084] PicSizeInSamplesY = pic_width_in_luma_samples pic_height_in_luma_samples (7-23)

[0085] PicWidthInSamplesC = pic_width_in_luma_samples / SubWidthC (7-24)

[0086] PicHeightInSamplesC = pic_height_in_luma_samples / SubHeightC (7-25)

[0087] 3.3.2 CTU in an image

[0088] Figures 6A-6C An example of CTB across image boundaries is shown. Figure 6A The CTB (Content Tolerance) across the bottom image boundary is shown. Figure 6B The CTB (Content Boundary) across the right edge of the image is shown. Figure 6CShows a CTB across the lower right picture boundary. Assume that the CTB / largest coding unit (LCU) size is indicated by M×N (usually M equals N), and for a CTB located at the picture boundary (or slice or stripe or other type of boundary, taking the picture boundary as an example), K×L samples are within the picture boundary, where K < M or L < N. For the CTBs such as Figures 6A-6C shown, the CTB size is still equal to M×N. However, the bottom boundary / right boundary of the CTB is outside the picture.

[0089] 3.4 Intra prediction

[0090] Figure 7 Shows an example of intra prediction modes. To capture any edge direction presented in natural videos, the number of directional intra modes is extended from 33 used in HEVC to 65. The extended directional modes are as shown in Figure 7 and the planar and direct current (DC) modes remain unchanged. These denser directional intra prediction modes apply to all block sizes and apply to both luminance and chrominance intra prediction.

[0091] As shown in Figure 7 , the angular intra prediction directions can be defined as clockwise from 45 degrees to -135 degrees. In VTM, for non-square blocks, multiple angular intra prediction modes are adaptively replaced by wide-angle intra prediction modes. The replaced modes are signaled and remapped to the indices of the wide-angle modes after parsing. The total number of intra prediction modes remains unchanged, e.g., 67, and the intra mode coding and decoding remain unchanged.

[0092] In HEVC, each intra-coded block has a square shape and the length of each side of the block is a power of 2. Therefore, no division operation is required to generate intra prediction values using the DC mode. In VVC, blocks can have a rectangular shape, which generally requires a division operation for each block. To avoid the division operation for DC prediction, only the longer side is used to calculate the average value of non-square blocks.

[0093] 3.5 Inter prediction

[0094] For each inter-frame predicted CU, motion parameters include motion vectors, reference picture indexes, reference picture list usage indexes, and extended information for new encoding / decoding features used to generate the VVC from the samples used for inter-frame prediction. 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 does not have significant residual coefficients, encoded / decoded motion vector increments, and / or reference picture indexes. A Merge mode is defined, thereby obtaining the motion parameters of the current CU from extended scheduling introduced from neighboring CUs (including spatial and temporal candidates) and VVCs. The Merge mode can be applied to any inter-frame predicted CU, not just skip mode. An alternative to the Merge mode is explicit transmission of motion parameters, where motion vectors, corresponding reference picture indexes for each reference picture list, reference picture list usage flags, and other useful information are explicitly transmitted via signaling for each CU.

[0095] 3.6 Deblocking Filter

[0096] Deblocking filtering is an example of a loop filter in a video codec. In VVC, the deblocking filtering process is applied to CU boundaries, transform subblock boundaries, and predictive subblock boundaries. Predictive subblock boundaries include prediction unit boundaries introduced by subblock-based temporal motion vector prediction (SbTMVP) and affine modes. Transform subblock boundaries include transform unit boundaries introduced by subblock transform (SBT) and intra-fractional sub-segmentation (ISP) modes, as well as transforms resulting from the implicit partitioning of large CUs. The processing order of the deblocking filter is defined as first performing horizontal filtering on the vertical edges of the entire image, and then performing vertical filtering on the horizontal edges. This specific order allows multiple horizontal or vertical filtering processes to be applied in parallel threads. The filtering process can also be implemented on a CTB-by-CTB basis with only a small processing latency.

[0097] The vertical edges in the image are first filtered. Then, using the samples modified by the vertical edge filtering process as input, the horizontal edges in the image are filtered. Vertical and horizontal edges in the CTB of each CTU are processed individually on a per-encoder-decoder-unit basis. The vertical edges of the codec blocks within an encodec unit are filtered, starting from the edge on the left-hand side of the codec block and proceeding geometrically through the edges towards the right-hand side of the codec block. The horizontal edges of the codec blocks within an encodec unit are filtered, starting from the edge on the top of the codec block and proceeding geometrically through the edges towards the bottom of the codec block.

[0098] Figure 8 An example of a block boundary in an image is shown. For example, Figure 8The image samples on an 8×8 grid, along with the horizontal and vertical block boundaries, and the non-overlapping blocks of the 8×8 samples, can be de-blocked in parallel.

[0099] 3.6.1 Boundary Decision

[0100] The filter is applied to the 8×8 block boundaries. Additionally, such boundaries must be transform block boundaries or codec sub-block boundaries, for example, due to the use of Affine Motion Prediction (ATMVP). For other boundaries, deblocking filtering is disabled.

[0101] 3.6.2 Boundary Strength Calculation

[0102] For transform block boundaries / encoder / decoder sub-block boundaries, if the boundary is located in an 8×8 grid, the boundary can be filtered, and the settings of bS[xDi][yDj] (where [xDi][yDj] represents the coordinates) of the edge are defined as in Tables 2 and 3, respectively.

[0103] Table 2 Boundary Strength (when SPS Intra-Block Copying (IBC) is disabled)

[0104]

[0105] Table 3 Boundary Strength (when SPS IBC is enabled)

[0106]

[0107] 3.6.3 Deblocking decision for the luminance component

[0108] Figure 9 An example involving the pixels used by the filter is shown. For example, Figure 9 The image shows pixels involved in filter on / off decisions and strong / weak filter selection. A wider and stronger luminance filter is used only if conditions 1, 2, and 3 are all true. Condition 1 is the "bulk condition." This condition detects whether samples on the P-side and Q-side belong to a bulk, represented by the variables bSidePisLargeBlk and bSideQisLargeBlk, respectively. bSidePisLargeBlk and bSideQisLargeBlk are defined as follows.

[0109] bSidePisLargeBlk = ((Edge type is vertical and p0 belongs to CU with width >= 32) || (Edge type is horizontal and p0 belongs to CU with height >= 32))? TRUE : FALSE

[0110] bSideQisLargeBlk = ((Edge type is vertical and q0 belongs to CU with width >= 32) || (Edge type is horizontal and q0 belongs to CU with height >= 32))? TRUE : FALSE

[0111] Based on bSidePisLargeBlk and bSideQisLargeBlk, condition 1 is defined as follows:

[0112] Condition 1 = (bSidePisLargeBlk || bSidePisLargeBlk) ? TRUE : FALSE

[0113] Next, if condition 1 is true, then condition 2 will be further checked. First, derive the following variables:

[0114] First, derive dp0, dp3, dq0, and dq3 using the HEVC method.

[0115] if (p side is greater than or equal to 32)

[0116] dp0 = (dp0 + Abs(p50 - 2)) p40 + p30 + 1) >> 1

[0117] dp3 = (dp3 + Abs(p53 - 2)) p43 + p33 + 1) >> 1

[0118] if (q side is greater than or equal to 32)

[0119] dq0 = (dq0 + Abs(q50 - 2)) q40 + q30 + 1) >> 1

[0120] dq3 = (dq3 + Abs(q53 - 2)) q43 + q33 + 1) >> 1

[0121] Condition 2 = (d < β) ? TRUE : FALSE

[0122] Where d = dp0 + dq0 + dp3 + dq3.

[0123] If conditions 1 and 2 are valid, then further check whether any of the blocks uses a sub-block:

[0124] If (bSidePisLargeBlk)

[0125] {

[0126] If (block P's mode == SUBBLOCKMODE)

[0127] Sp = 5

[0128] else

[0129] Sp = 7

[0130] }

[0131] else

[0132] Sp = 3

[0133] If (bSideQisLargeBlk)

[0134] {

[0135] If (block Q's mode == SUBBLOCKMODE)

[0136] Sq = 5

[0137] else

[0138] Sq = 7

[0139] }

[0140] else

[0141] Sq = 3

[0142] Finally, if both conditions 1 and 2 are valid, the deblocking method will check condition 3 (the strong filter condition), which is defined as follows. In condition 3, StrongFilterCondition, the following variables are derived:

[0143] Derive dpq using the HEVC method.

[0144] Derive sp3 = Abs( p3 - p0 ) using the HEVC method

[0145] if (p side is greater than or equal to 32)

[0146] if (Sp == 5)

[0147] sp3 = ( sp3 + Abs( p5 - p3 ) + 1) >> 1

[0148] else

[0149] sp3 = ( sp3 + Abs( p7 - p3 ) + 1) >> 1

[0150] Derive sq3 = Abs( q0 - q3 ) using the HEVC method.

[0151] if (q side is greater than or equal to 32)

[0152] If (Sq == 5)

[0153] sq3 = ( sq3 + Abs( q5 - q3 ) + 1) >> 1

[0154] else

[0155] sq3 = ( sq3 + Abs( q7 - q3 ) + 1) >> 1

[0156] According to HEVC, StrongFilterCondition = (dpq < (β >> 2), sp3 + sq3 < (3)). β >> 5), and Abs(p0 - q0) is less than (5). tC + 1 ) >> 1) ? TRUE : FALSE.

[0157] 3.6.4 A more robust deblocking filter for luminance

[0158] When samples on either side of the boundary belong to a large block, a bilinear filter is used. Samples belonging to a large block are defined as those with a vertical edge width >= 32 and a horizontal edge height >= 32. The bilinear filter is listed below. In the above HEVC deblocking, the block boundary samples pi (i = 0 to Sp-1) and qi (i = 0 to Sq-1) (pi and qi are the i-th samples in the row used for filtering the vertical edge, or the i-th samples in the column used for filtering the horizontal edge) are then replaced by the following linear interpolation:

[0159]

[0160]

[0161] in and The item is the location-related limiting as described above, and , , , and As shown below.

[0162] 3.6.5 Color Deblocking Decision

[0163] A strong chroma filter is used on both sides of the block boundary. Here, a chroma filter is selected when the chroma edge on both sides is greater than or equal to 8 (chroma position), and the following decision is satisfied with three conditions: The first is the decision for boundary strength and the size of the block. The filter can be applied when the block width or height orthogonally spanning the block edge in the chroma sample domain is equal to or greater than 8. The second and third are essentially the same as the decision for HEVC luminance deblocking, which are the on / off decision and the strong filter decision, respectively.

[0164] In the first decision, the boundary strength (bS) is modified for chroma filtering, and conditions are checked sequentially. If a condition is met, the remaining conditions with lower priority are skipped. Chroma deblocking is performed when bS equals 2, or when bS equals 1 when a large block boundary is detected. The second and third conditions are essentially the same as the HEVC luma strong filter decision below.

[0165] In the second condition, d is then derived using the HEVC luminance deblocking method. The second condition will be true when d is less than β. In the third condition, StrongFilterCondition is derived as follows:

[0166] Derive dpq using the HEVC method.

[0167] Derive sp3 = Abs( p3 - p0 ) using the HEVC method

[0168] Derive sq3 = Abs( q0 - q3 ) using the HEVC method.

[0169] According to the HEVC design, StrongFilterCondition = (dpq < (β >> 2), sp3 + sq3 < (β >> 3), and Abs(p0 - q0) < (5). tC + 1) >> 1)

[0170] 3.6.6 Strong Deblocking Filter for Chromaticity

[0171] The following strong deblocking filter is defined for chroma:

[0172] p2′= (3 p3+2 p2+p1+p0+q0+4) >> 3

[0173] p1′= (2 p3+p2+2 p1+p0+q0+q1+4) >> 3

[0174] p0′= (p3+p2+p1+2 p0+q0+q1+q2+4) >> 3

[0175] The example chroma filter performs deblocking on a 4×4 chroma sample grid.

[0176] 3.6.7 Location-related amplitude limiting

[0177] Position-dependent limiting (tcPD) is applied to the output samples of a luminance filtering process involving modifications to strong and long filters at the boundaries of 7, 5, and 3 samples. Assuming a quantization error distribution, the limiting value can be increased for samples expected to have higher quantization noise, thus anticipating a higher deviation between the reconstructed sample value and the true sample value.

[0178] For each P or Q boundary filtered by an asymmetric filter, a position-related threshold table is selected from two tables (e.g., Tc7 and Tc3 listed below) that serve as edge information, based on the results of the decision process:

[0179] Tc7 = {6, 5, 4, 3, 2, 1, 1}; Tc3 = {6, 4, 2};

[0180] tcPD = (Sp == 3) ? Tc3 : Tc7;

[0181] tcQD = (Sq == 3) ? Tc3 : Tc7;

[0182] For P or Q boundaries filtered by a short symmetric filter, a lower-amplitude position correlation threshold is applied:

[0183] Tc3 = { 3, 2, 1};

[0184] After defining the threshold, the filtered p'i and q'i sample values ​​are limited according to the tcP and tcQ limiting values:

[0185] p''i = Clip3(p'i + tcPi, p'i - tcPi, p'i );

[0186] q''j = Clip3(q'j + tcQj, q'j - tcQj, q'j );

[0187] Where p'i and q'i are the filtered sample values, p''i and q''j are the output sample values ​​after clipping, and tcPi and tcQj are the clipping thresholds derived from the VVC tc parameters, tcPD, and tcQD. The function Clip3 is the clipping function as specified in VVC.

[0188] 3.6.8 Sub-block Removal and Adjustment

[0189] To enable parallel-friendly deblocking using both long filters and sub-block deblocking, the long filter is restricted to modifying a maximum of 5 samples on the side using sub-block deblocking (AFFINE or ATMVP or decoder-side motion vector refinement (DMVR)), as shown in the long filter's brightness control. Extending this, sub-block deblocking is adjusted such that sub-block boundaries on the 8×8 grid near the CU or implicit TU boundaries are restricted to modifying a maximum of two samples on each side.

[0190] The following applies to sub-block boundaries that are not aligned with the CU boundary.

[0191] If (block Q's mode == SUBBLOCKMODE && edge != 0) {

[0192] if (!(implicitTU && (edge ​​== (64 / 4))))

[0193] if (edge ​​== 2 || edge == (orthogonalLength - 2) || edge== (56 / 4) || edge == (72 / 4))

[0194] Sp = Sq = 2;

[0195] else

[0196] Sp = Sq = 3;

[0197] else

[0198] Sp = Sq = bSideQisLargeBlk ? 5:3

[0199] }

[0200] Where edge = 0 corresponds to the CU boundary, edge = 2 or orthogonalLength-2 corresponds to the sub-block boundary 8 samples away from the CU boundary, etc. If implicit partitioning of TU is used, then implicit TU is true.

[0201] 3.7 Sample point adaptive compensation

[0202] Sample Adaptive Compensation (SAO) is applied to the reconstructed signal after the deblocking filter by using an offset specified by the encoder for each CTB. The video encoder first decides whether to apply the SAO process to the current slice. If SAO is applied to a slice, each CTB is classified into one of five SAO types as shown in Table 4. The concept of SAO is to classify pixels into multiple categories and reduce distortion by adding an offset to the pixels in each category. SAO operations include Edge Compensation (EO) and Band Compensation (BO), where EO uses edge attributes to classify pixels in SAO types 1 through 4, and BO uses pixel intensity to classify pixels in SAO type 5. Each applicable CTB has SAO parameters including sao_merge_left_flag, sao_merge_up_flag, SAO type, and four offsets. If sao_merge_left_flag equals 1, the current CTB will reuse the SAO type and offset of the left CTB. If sao_merge_up_flag equals 1, the current CTB will reuse the SAO type and offset of the upper CTB.

[0203] Table 4 Specifications for SAO Types

[0204]

[0205] 3.8 Adaptive Loop Filter

[0206] Adaptive Loop Filtering (ALF) for video encoding and decoding minimizes the mean square error between the original and decoded samples using Wiener-based adaptive filters. ALF is located at the final processing stage of each picture and can be considered a tool for capturing and repairing artifacts from previous stages. Appropriate filter coefficients are determined by the encoder and explicitly transmitted to the decoder via the signal. To achieve better encoding and decoding efficiency, especially for high-resolution video, local adaptation is used for the luminance signal by applying different filters to different regions or blocks in the picture. In addition to filter adaptation, filter on / off control at the codec tree unit (CTU) level also contributes to improved encoding and decoding efficiency. Syntactically, filter coefficients are sent in a picture-level header called the adaptive parameter set, and the filter on / off flags of the CTUs are interleaved at the CTU level in the stripe data. This syntax design not only supports picture-level optimization but also achieves low encoding latency.

[0207] 3.8.1 Signaling of Parameters

[0208] According to the ALF design in VTM, filter coefficients and clipping indices are carried in the ALF Adaptive Parameter Set (APS). The ALF APS can include up to eight chromaticity filters and a luma filter set with up to 25 filters. An index is also included for each of the 25 luma categories. Categories with the same index share the same filters. By merging different categories, the number of bits required to represent the filter coefficients is reduced. The absolute values ​​of the filter coefficients are represented using 0th-order Exp-Golomb code, followed by a sign bit for non-zero coefficients. When clipping is enabled, a two-bit fixed-length code is also used for each filter coefficient transmitted via signal transmission as a clipping index. The decoder can use up to eight ALF APSs simultaneously.

[0209] The filter control syntax elements of ALF in VTM include two types of information. First, the ALF on / off flag is transmitted via signaling at the sequence, picture, strip, and CTB levels. Chroma ALF can only be enabled at the picture and strip levels if the luma ALF is enabled at the corresponding level. Second, if the ALF is enabled at that level, filter usage information is transmitted via signaling at the picture, strip, and CTB levels. If all strips within a picture use the same APS, the referenced ALF APSID is encoded or decoded at the strip level or the picture level. The luma component can reference up to 7 ALF APSs, and the chroma component can reference 1 ALF APS. For the luma CTB, an index is transmitted via signaling to indicate which ALF APS or offline-trained luma filter set is used. For the chroma CTB, the index indicates which filter in the referenced APS is used.

[0210] The data syntax elements of ALF associated with the luminance component in VTM are listed below:

[0211]

[0212] `alf_luma_filter_signal_flag` equal to 1 specifies the set of luminance filters transmitted via signal transmission. `alf_luma_filter_signal_flag` equal to 0 specifies that no luminance filter set is transmitted via signal transmission. `alf_luma_clip_flag` equal to 0 specifies that linear adaptive loop filtering is applied to the luminance component. `alf_luma_clip_flag` equal to 1 specifies that nonlinear adaptive loop filtering can be applied to the luminance component. `alf_luma_num_filters_signalled_minus1` plus 1 specifies the number of adaptive loop filter classes whose luminance coefficients can be transmitted via signal transmission. The value of `alf_luma_num_filters_signalled_minus1` must be in the range of 0 to NumAlfFilters - 1 (inclusive). `alf_luma_coeff_delta_idx[filtIdx]` specifies the index of the adaptive loop filter luminance coefficient increment of the filter class transmitted via signal transmission, indicated by `filtIdx` in the range of 0 to NumAlfFilters - 1. When alf_luma_coeff_delta_idx[filtIdx] does not exist, it is presumed to be equal to 0. The length of alf_luma_coeff_delta_idx[filtIdx] is Ceil(Log2(alf_luma_num_filters_signalled_minus1 + 1)) bits. The value of alf_luma_coeff_delta_idx[filtIdx] must be in the range from 0 to alf_luma_num_filters_signalled_minus1 (inclusive).

[0213] `alf_luma_coeff_abs[ sfIdx ][ j ]` specifies the absolute value of the j-th coefficient of the luminance filter transmitted through the signal, indicated by `sfIdx`. When `alf_luma_coeff_abs[ sfIdx ][ j ]` does not exist, it is presumed to be equal to 0. The value of `alf_luma_coeff_abs[ sfIdx ][ j ]` must be in the range of 0 to 128 (inclusive). `alf_luma_coeff_sign[ sfIdx ][ j ]` specifies the sign of the j-th luminance coefficient of the filter indicated by `sfIdx`, as follows:

[0214] If alf_luma_coeff_sign[ sfIdx ][ j ] equals 0, the corresponding luminance filter coefficient has a positive value.

[0215] Otherwise (alf_luma_coeff_sign[ sfIdx ][ j ] equals 1), the corresponding luminance filter coefficient has a negative value.

[0216] When alf_luma_coeff_sign[ sfIdx ][ j ] does not exist, it is presumed to be equal to 0.

[0217] `alf_luma_clip_idx[ sfIdx ][ j ]` specifies the limiting index to be used before multiplying by the j-th coefficient of the luminance filter transmitted through the signal, indicated by `sfIdx`. When `alf_luma_clip_idx[ sfIdx][ j ]` does not exist, it is presumed to be equal to 0. The codec tree unit syntax elements of the ALF associated with the luminance component in the VTM are listed below:

[0218]

[0219] `alf_ctb_flag[ cIdx ][ xCtb >> CtbLog2SizeY ][ yCtb >> CtbLog2SizeY ]` equal to 1 indicates that the adaptive loop filter is applied to the codec tree block of the codec tree unit at the luma position (xCtb, yCtb), for the color component indicated by `cIdx`. `alf_ctb_flag[ cIdx ][ xCtb >> CtbLog2SizeY ][ yCtb >> CtbLog2SizeY ]` equal to 0 indicates that the adaptive loop filter is not applied to the codec tree block of the codec tree unit at the luma position (xCtb, yCtb), for the color component indicated by `cIdx`.

[0220] When `alf_ctb_flag[ cIdx ][ xCtb >> CtbLog2SizeY ][ yCtb >> CtbLog2SizeY]` does not exist, it is presumed to be equal to 0. `alf_use_aps_flag` equal to 0 specifies that one of the fixed filter sets is applied to the luma CTB. `alf_use_aps_flag` equal to 1 specifies that a filter set from the APS is applied to the luma CTB. When `alf_use_aps_flag` does not exist, it is presumed to be equal to 0. `alf_luma_prev_filter_idx` specifies the previous filter applied to the luma CTB. The value of `alf_luma_prev_filter_idx` must be in the range of 0 to `sh_num_alf_aps_ids_luma - 1` (inclusive). When `alf_luma_prev_filter_idx` does not exist, it is presumed to be equal to 0.

[0221] The variable AlfCtbFiltSetIdxY[xCtb >> CtbLog2SizeY ][ yCtb >> CtbLog2SizeY ], which represents the filter set index of the luminance CTB at a specified location (xCtb, yCtb), is derived as follows:

[0222] If alf_use_aps_flag equals 0, AlfCtbFiltSetIdxY[ xCtb >> CtbLog2SizeY ][ yCtb >> CtbLog2SizeY ] is set to equal alf_luma_fixed_filter_idx.

[0223] Otherwise, AlfCtbFiltSetIdxY[ xCtb >> CtbLog2SizeY ][ yCtb >> CtbLog2SizeY] is set to equal to 16 + alf_luma_prev_filter_idx.

[0224] alf_luma_fixed_filter_idx specifies the fixed filter to be applied to the luminance CTB. The value of alf_luma_fixed_filter_idx must be in the range of 0 to 15 (inclusive).

[0225] Based on the VTM-based ALF design, the ECM ALF design further introduces the concept of alternative filter sets into the luminance filter. The luminance filter is trained with multiple alternatives / rounds based on the updated luminance CTU ALF on / off decisions for each alternative / round. In this way, multiple filter sets will be associated with each trained alternative, and the class merging results for each filter set can be different. Each CTU can select the optimal filter set via RDO, and the relevant alternative information will be transmitted via signal transmission. The data syntax elements of the ALF associated with the luminance component in the ECM are listed below:

[0226]

[0227] `alf_luma_num_alts_minus1` incremented by 1 specifies the number of alternative filter sets for the luminance component. The value of `alf_luma_num_alts_minus1` must be in the range of 0 to 3 (inclusive). `alf_luma_clip_flag[altIdx]` equal to 0 specifies that linear adaptive loop filtering is applied to the alternative luminance filter set for the luminance component at index `altIdx`. `alf_luma_clip_flag[altIdx]` equal to 1 specifies that nonlinear adaptive loop filtering can be applied to the alternative luminance filter set for the luminance component at index `altIdx`. `alf_luma_num_filters_signalled_minus1[altIdx]` incremented by 1 specifies the number of adaptive loop filter categories through which the luminance coefficients of the alternative luminance filter set at index `altIdx` can be transmitted via signal transmission. The value of alf_luma_num_filters_signalled_minus1[altIdx] must be in the range of 0 to NumAlfFilters - 1 (inclusive).

[0228] `alf_luma_coeff_delta_idx[altIdx][filtIdx]` specifies an index of the adaptive loop filter luminance coefficient increments transmitted through the signal, indicated by `filtIdx` ranging from 0 to `NumAlfFilters - 1`, used to index the alternative luminance filter set for `altIdx`. When `alf_luma_coeff_delta_idx[filtIdx][altIdx]` does not exist, it is presumed to be equal to 0. The length of `alf_luma_coeff_delta_idx[altIdx][filtIdx]` is Ceil(Log2(alf_luma_num_filters_signalled_minus1[altIdx] + 1)) bits. The value of `alf_luma_coeff_delta_idx[altIdx][filtIdx]` must be within the range of 0 to `alf_luma_num_filters_signalled_minus1[altIdx]` (inclusive). `alf_luma_coeff_abs[altIdx][sfIdx][j]` specifies the absolute value of the j-th coefficient of the luminance filter indicated by `sfIdx` in the alternative luminance filter set indexed at `altIdx`. When `alf_luma_coeff_abs[altIdx][sfIdx][j]` does not exist, it is presumed to be equal to 0. The value of alf_luma_coeff_abs[altIdx][sfIdx][j] must be in the range of 0 to 128 (inclusive).

[0229] `alf_luma_coeff_sign[altIdx][sfIdx][j]` specifies the sign of the j-th luminance coefficient of the filter indicated by `sfIdx` in the alternative luminance filter set with index `altIdx`, as follows:

[0230] If alf_luma_coeff_sign[altIdx][sfIdx][j] equals 0, the corresponding luminance filter coefficient has a positive value.

[0231] Otherwise (alf_luma_coeff_sign[altIdx][sfIdx][j] equals 1), the corresponding luminance filter coefficient has a negative value.

[0232] When alf_luma_coeff_sign[altIdx][sfIdx][j] does not exist, it is presumed to be equal to 0.

[0233] `alf_luma_clip_idx[altIdx][sfIdx][j]` specifies the limiting index to be used before the j-th coefficient of the luminance filter transmitted through the signal, indicated by `sfIdx`, in the alternative luminance filter set with index `altIdx`. When `alf_luma_clip_idx[altIdx][sfIdx][j]` does not exist, it is presumed to be equal to 0. The codec tree unit syntax elements of the ALF associated with the luminance component in the ECM are listed below:

[0234]

[0235] `alf_ctb_luma_filter_alt_idx[ xCtb >> CtbLog2SizeY ][ yCtb >> CtbLog2SizeY ]` specifies the index of the alternative luma filter applied to the luma component of the codec tree block at the luma location (xCtb, yCtb). If `alf_ctb_luma_filter_alt_idx[ xCtb >> CtbLog2SizeY ][ yCtb >> CtbLog2SizeY ]` does not exist, it is presumed to be equal to 0.

[0236] 3.8.2 Filter Shape

[0237] Figure 10 An example of ALF filter shape is shown. In JEM, there are a maximum of three diamond filter shapes (such as...). Figure 10 (As shown) can be selected for the luma component. At the image level, the filter shape used for the luma component is indicated by a signal transmission index. Each square represents a sample, and Ci (i = 0~6 (left), 0~12 (middle), 0~20 (right)) represents the coefficient to be applied to the sample. For the chroma component in the image, a 5×5 rhombus shape is always used. In VVC, a 7×7 rhombus shape is always used for luma, while a 5×5 rhombus shape is always used for chroma.

[0238] 3.8.3 Classification of ALF

[0239] Each 2×2 (or 4×4) block is classified into one of 25 categories. The classification index C is based on its directionality. and activity The quantization value is derived as follows:

[0240] .

[0241] In order to calculate and First, the gradients in the horizontal, vertical, and two diagonal directions are calculated using the one-dimensional Laplacian operator:

[0242]

[0243]

[0244]

[0245]

[0246] index and Referencing the coordinates of the top left sample point in the 2×2 block, and Indicator coordinates The reconstructed sample points are then used. Then, the gradients in the horizontal and vertical directions are... The maximum and minimum values ​​are set as follows:

[0247] , ,

[0248] Furthermore, the maximum and minimum values ​​of the gradients in the two diagonal directions are set as follows:

[0249] , ,

[0250] In order to derive directionality The values ​​are compared with each other and with two thresholds. and Compare:

[0251] Step 1. If and If both are true, then Set as ;

[0252] Step 2. If If yes, continue from step 3; otherwise, continue from step 4.

[0253] Step 3. If ,but Set as ;otherwise Set as ;

[0254] Step 4. If ,but Set as ;otherwise Set as .

[0255] Activity value Calculated as:

[0256]

[0257] It is further quantized to the range of 0 to 4 (inclusive), and the quantized value is represented as For the two chromaticity components in the image, no classification method is applied; instead, a single ALF coefficient set is applied to each chromaticity component.

[0258] 3.8.4 Geometric Transformation of Filter Coefficients

[0259] Before filtering each 2×2 block, geometric transformations (such as rotation or diagonal and vertical flips) are applied to the filter coefficients associated with coordinates (k, l), based on the gradient values ​​calculated for that block. This is equivalent to applying these transformations to samples in the filter's support region. The idea is to make them more similar by aligning the directions of different blocks to which ALF is applied.

[0260] Three geometric transformations are introduced, including diagonal flip, vertical flip, and rotation:

[0261] diagonal:

[0262] Vertical Flip: ,

[0263] Rotation:

[0264] in It is the size of the filter, and These are coefficient coordinates, which make the position... In the top left corner, and in position In the bottom right corner. Based on the gradient values ​​calculated for the block, the transform is applied to the filter coefficients f(k, l). The relationship between the transform and the four gradients in the four directions is summarized in Table 5.

[0265] Figure 11 An example of the transform coefficients used as the support for a 5×5 rhombus filter is shown. For example, Figure 11 The transformation coefficients for each position based on a 5×5 rhombus are shown.

[0266] Table 5 shows the mapping between gradients and transformations computed for a single block.

[0267]

[0268] 3.8.5 Filtering Process

[0269] On the decoder side, when ALF is enabled for a block, each sample within the block... Filtering causes sample values As shown below, where L represents the filter length, Represents the filter coefficients. This represents the decoded filter coefficients.

[0270]

[0271] Figure 12 This example illustrates relative coordinates supported by a 5×5 diamond filter, assuming the current sample point's coordinates (i, j) are (0, 0). Sample points at different coordinates filled with the same color are multiplied by the same filter coefficients.

[0272] 3.8.6 Restating Nonlinear Filtering

[0273] Linear filtering can be restated in the following expression without affecting encoding / decoding efficiency:

[0274]

[0275] in They are the same filter coefficients.

[0276] VVC introduces nonlinearity by using a simple limiting function to measure the value at neighboring sample points. Compared with the current sample value being filtered ( When the difference is too large, the influence of neighboring sample values ​​is reduced, thus making ALF more efficient. More specifically, the ALF filter is modified as follows:

[0277]

[0278] in It is a limiting function. It is the limiting parameter, which depends on Filter coefficients. The encoder performs optimization to find the optimal values. .

[0279] Specify limiting parameters for each ALF filter Each filter coefficient is transmitted with a limiting value via signal transmission. This means that each luminance filter can transmit a maximum of 12 limiting values ​​via signal transmission in the bitstream, and the chrominance filter can transmit a maximum of 6 limiting values ​​via signal transmission. To limit signaling costs and encoder complexity, only 4 fixed values ​​are used, which are the same for both inter-frame and intra-frame stripes.

[0280] Because the variance of local differences in luminance is typically higher than that in chrominance, two different sets of filters are applied for luminance and chrominance. The maximum sample value in each set (here, 1024 for a 10-bit bit depth) is also introduced so that clipping can be disabled if unnecessary. These four values ​​are chosen by dividing the entire range of luminance sample values ​​(encoded and decoded on 10 bits) and the range of chrominance from 4 to 1024 into approximately equal parts in the logarithmic domain. More precisely, the luminance table of clipping values ​​has been obtained using the following formula:

[0281] AlfClip L Where M=2 10 And N=4.

[0282] Similarly, the colorimetric table for the limiting values ​​is obtained using the following formula:

[0283] AlfClip C Where M=2 10 N=4 and A=4.

[0284] 3.9 Bilateral Loop Filter

[0285] 3.9.1 Bilateral Image Filter

[0286] Bilateral image filtering is a nonlinear filter that smooths noise while preserving edge structure. Bilateral filtering is a technique where the filter weights decrease not only as the distance between samples decreases but also as the intensity difference increases. This improves the smoothing of overly smoothed edges. The weights are defined as:

[0287]

[0288] in and It is the distance in the vertical and horizontal directions, and It is the intensity difference between sample points.

[0289] The edge-preserving denoising bilateral filter employs low-pass Gaussian filters for both the domain and range filters. The domain low-pass Gaussian filter assigns higher weights to pixels spatially closer to the center pixel. The range low-pass Gaussian filter assigns higher weights to pixels similar to the center pixel. Combining the range and domain filters, the bilateral filter at edge pixels becomes a thin Gaussian filter, oriented along the edge and significantly reduced in the gradient direction. This is why the bilateral filter can smooth noise while preserving edge structure.

[0290] 3.9.2 Bilateral Filters in Video Encoding and Decoding

[0291] Bilateral filters in video encoding and decoding are encoding and decoding tools used for VVC [2]. The filter acts as a loop filter in parallel with the Sample Adaptive Compensation (SAO) filter. Both the bilateral filter and the SAO act on the same input sample, each filter produces an offset, and these offsets are then added to the input sample to produce an output sample, which is then clipped before proceeding to the next stage. Spatial filtering intensity Determined by the block size, smaller blocks are filtered more strongly, and the intensity of the filter is determined. Determined by the quantization parameters, with stronger filtering used for higher QP values. Only the four nearest samples are used, therefore the filtered sample intensity... It can be calculated as

[0292]

[0293] in Indicates the intensity of the central sample point. This indicates the intensity difference between the center sample point and the sample point above it. These represent the intensity differences between the center sample point and the sample points below, to the left, and to the right, respectively.

[0294] 4. The technical problem solved by the disclosed technical solution

[0295] The example design of the Adaptive Loop Filter (ALF) in video encoding and decoding has the following problems.

[0296] In the example ALF and Cross-Component ALF (CCALF) designs of ECM, additional side information (e.g., residual or reconstructed samples before the ALF or CCALF) is also used, in addition to the reconstructed samples before the ALF or CCALF. This side information is stored in memory. However, the line cache for ALF and / or CCALF is limited, so this additional side information breaks the line cache limitation.

[0297] 5. List of solutions and implementation examples

[0298] To address the aforementioned problems, the following summarized methods are disclosed. The embodiments should be considered as examples for explaining general concepts and should not be interpreted in a narrow sense. Furthermore, these embodiments can be applied individually or in any combination.

[0299] It should be noted that the disclosed method can be used as a loop filter or post-processing.

[0300] In this disclosure, a video unit can refer to a sequence, picture, subpicture, strip, CTU, block, and / or region. A video unit may include one color component or multiple color components.

[0301] In this disclosure, an ALF processing unit can refer to a sequence, image, sub-image, stripe, CTU, block, region, or sample. An ALF processing unit can include one or more color components. Furthermore, side information can include encoding / decoding information other than the samples to be filtered by the current filter, and such side information can be used to determine the current filter's use of the samples to be filtered.

[0302] The padding method used for line cache constraints can be represented as “mirror padding”, where the first unavailable sample at (i, j) is padded, and the second sample (e.g., the corresponding sample at (m, n) at the same distance from the current luminance sample) defined by the “corresponding sample of the first sample” in the filter support of ALF / CCALF is also padded, even when the second sample is available.

[0303] In one example, vertical fill is used such that the sample point to be filled at (x, y1) is set to be equal to the sample point at (x, y2), where y1 represents the y coordinate of the sample point or the corresponding sample point, and y2 represents the y coordinate of the sample point used for filling.

[0304] In one example, horizontal fill is used such that the sample point to be filled at (x1, y) is set to be equal to the sample point at (x2, y), where x1 represents the x-coordinate of the sample point or the corresponding sample point, and x2 represents the x-coordinate of the sample point used for filling.

[0305] The filling method used for images, sub-images, stripes, piece boundaries and / or 360-degree video virtual boundaries, normal boundaries (e.g., top and bottom boundaries) can be represented as "repeated filling", where if a sample to be used is outside the boundary, the sample is copied from an available sample inside the boundary.

[0306] Line buffer of loop filter

[0307] 1. It is proposed that whether and / or how to use additional edge information depends on whether the sample points associated with the additional edge information are at the boundary.

[0308] a. The boundary can be a CTU boundary, a CTU row boundary, or a virtual boundary.

[0309] b. Samples at the boundary can also be referred to as "at the line buffer".

[0310] c. It is proposed whether and / or how to use additional side information can be the same as whether and / or how to use reconstructed samples at the line buffer of one or more loop filters.

[0311] d. In one example, a loop filter may refer to a DBF, and / or a SAO, and / or a cross-component SAO (CCSAO), and / or an ALF luminance, and / or an ALF chrominance, and / or a CCALF, and / or a bilateral filter (BIF), and / or a BIF chrominance, and variations thereof.

[0312] e. In one example, row caching limits for additional side information can be applied to different stages in one or more loop filters.

[0313] i. In one example, row caching limits for additional edge information can be applied to the filtering stage.

[0314] ii. In one example, row caching limits for additional edge information can be applied to the classification phase.

[0315] iii. In one example, row caching limits for additional edge information can be applied to both the filtering and classification stages.

[0316] f. In one example, additional edge information could refer to predicted samples, residual samples, reconstructed samples before / after a particular loop filter, or intermediate values ​​within a particular loop filter.

[0317] i. In one example, the intermediate value can refer to the output of the offline or online filter of ALF / CCALF.

[0318] ii. In one example, the input used to generate intermediate values ​​can refer to the reconstruction prior to DBF.

[0319] iii. In one example, the input used to generate intermediate values ​​can refer to the reconstruction prior to ALF.

[0320] iv. In one example, the input used to generate intermediate values ​​can refer to the predicted samples.

[0321] v. In one example, the input used to generate intermediate values ​​could refer to residual samples.

[0322] g. In one example, additional edge information may refer to encoding / decoding information, such as prediction mode, and / or boundary strength, and / or QP.

[0323] h. In one example, the method for filling unavailable samples of additional edge information at the row cache can be the same as the method for filling unavailable samples of the reconstructed samples.

[0324] i. In one example, the fill method could refer to repeated (one-sided) fill.

[0325] ii. In one example, the fill method could refer to mirror (symmetric) fill.

[0326] i. Alternatively, whether and / or how to use additional side information can differ from whether and / or how to use reconstructed samples at the line buffer of one or more loop filters.

[0327] i. In one example, the number of rows (N1) used in the row cache for additional edge information can be different from the number of rows (N2) used in the row cache for reconstructed samples.

[0328] 1) In one example, N1 <N2。

[0329] 2) In one example, N1 > N2.

[0330] 3) In one example, N1=0.

[0331] ii. In one example, additional edge information is not stored in the row cache.

[0332] iii. In one example, the method for filling unavailable samples with additional edge information at the row cache can be different from the method for filling unavailable samples with reconstructed samples.

[0333] 2. In one example, the edge information may come from one or more color components.

[0334] a. In one example, color components can refer to Y, Cb, or Cr in the YCbCr color space.

[0335] b. In one example, color components can refer to G, B, or R in the GBR color space.

[0336] c. In one example, a color component can refer to any other color space used in video encoding / decoding.

[0337] 3. It proposes to execute ALF chroma and CCALF in parallel, instead of sequentially.

[0338] a. In one example, the first offset (O1) is generated from ALF chroma and the second offset (O2) is generated from CCALF. O1 and O2 are first added to the chroma samples and then a clipping operation is performed.

[0339] i. For example, R' = clip(R + O1 + O2), where R represents the current chroma sample, R' represents the sample filtered by ALF chroma and CCALF, and clip() represents the clipping operation.

[0340] b. In one example, a clipping operation can be performed on both ALF chroma and CCALF.

[0341] 4. In one example, the disclosed methods may be used in post-processing and / or pre-processing.

[0342] How are the boundary positions of the loop filter defined?

[0343] 5. The “luminance loop filter boundary” can be derived for luminance-related edge information, and the “chrominance loop filter boundary” can be derived for chrominance-related edge information. The “luminance loop filter boundary” can be different from the “chrominance loop filter boundary”.

[0344] a. In one example, the “luminance loop filter boundary” can be derived and used for luminance-related edge information in DBF / BF / SAO / CCSAO / ALF / CCALF.

[0345] b. In one example, the “chroma loop filter boundary” can be derived and used for chroma-related edge information in DBF / BF / SAO / CCSAO / ALF / CCALF.

[0346] c. In one example, the “chroma loop filter boundary” can depend on the color format and / or the filtering method.

[0347] i. For example, the “chroma loop filter boundary” can be derived in different ways for 4:2:0 color format and 4:2:2 / 4:4:4 color format.

[0348] d. The “luminance loop filter boundary” location can refer to the top boundary location, or / and the bottom boundary location, or / and the left boundary location, or / and the right boundary location.

[0349] e. In one example, the derivation of the "luminance loop filter boundary" position can depend on the variable vbOffset, which specifies the offset of the loop filter virtual boundary (or the distance between the loop filter virtual boundary and the bottom boundary of the current CTB), and / or the variable M, which specifies the offset relative to the top boundary of the current CTB. The luminance position of the current edge information sample relative to the upper left sample of the current luminance CTB is represented as (x, y). The luminance position of the upper left sample of the current luminance CTB relative to the upper left sample of the current image is (xCtb, yCtb), and the size of the current luminance CTB is CtbSizeY.

[0350] i. In one example, when y - (CtbSizeY - vbOffset) is greater than or equal to 0, the top boundary position can be set to be equal to yCtb + CtbSizeY - vbOffset.

[0351] ii. In one example, if the top boundary of the current CTB is the top boundary of a slice / strip / subpicture and the loop filter across slice / strip / subpicture is disabled, then the top boundary position can be set to equal yCtb when y is less than M.

[0352] iii. In one example, when CtbSizeY - vbOffset - y is greater than 0 and less than N, the bottom boundary position can be set to be equal to yCtb + CtbSizeY - vbOffset.

[0353] iv. In one example, if the bottom boundary of the current CTB is the bottom boundary of a slice / strip / subpicture, and the loop filter across slice / strip / subpicture is disabled, then the bottom boundary position can be set to equal yCtb + CtbSizeY when CtbSizeY - y is less than L.

[0354] f. In one example, the “chroma loop filter boundary” used in the 4:2:0 format is derived in the same way as the first “luminance loop filter boundary”.

[0355] i. In one example, when the chroma format is 4:2:0, the same value of vbOffset can be used for the luminance and chroma-related edge information during the derivation of the top and / or bottom boundary positions.

[0356] 1) In one example, vbOffset is an integer, such as 4.

[0357] ii. In one example, when the chroma format is 4:2:0, the same values ​​of M, N, and L can be used for the luminance and chroma-related edge information during the derivation of the top and / or bottom boundary positions.

[0358] 1) In one example, M, N, and L are integers, such as M = 3, N = 5, and L = 5.

[0359] g. In one example, the “chroma loop filter boundary” and the “luminance loop filter boundary” used in the 4:2:2 / 4:4:4 chroma format are derived in different ways.

[0360] i. In one example, when the chroma format is 4:2:2 / 4:4:4, different values ​​of vbOffset can be used for luminance and chroma-related edge information during the derivation of the top and / or bottom boundary positions.

[0361] 1) In one example, vbOffset1 can be used for chroma-related edge information, and vbOffset2 can be used for luminance-related edge information. vbOffset1 can be different from vbOffset2, for example, vbOffset1 = 2 and vbOffset2 = 4.

[0362] ii. In one example, when the chroma format is 4:2:2 / 4:4:4, different values ​​of vbOffset can be used for chroma-related edge information when the top boundary position and / or bottom boundary position is derived.

[0363] iii. In one example, when the chroma format is 4:2:2 / 4:4:4, different values ​​of M, N, and L can be used for luminance and chroma-related edge information during the derivation of the top and / or bottom boundary positions.

[0364] 1) In one example, M1, N1, and L1 are used for chroma-related edge information, and M2, N2, and L2 are used for luminance-related edge information, where M1 may not be equal to M2, N1 may not be equal to N2, and L1 may not be equal to L2.

[0365] a) In one example, M1 = 2, M1 = 3, L1 = 3, and M2 = 3, N2 = 5, L2 = 5.

[0366] 6. In one example, edge information samples can be filled at the boundary locations.

[0367] a. In one example, when encountering a brightness boundary location, brightness-related edge information samples can be filled.

[0368] b. In one example, when a chromaticity boundary location is encountered, chromaticity-related edge information samples can be filled.

[0369] c. In one example, side information samples can be filled at different stages of the loop filter.

[0370] i. In one example, this stage could be the classification of filters trained offline.

[0371] ii. In one example, this stage could be the classification of an online-trained filter.

[0372] iii. In one example, this stage could be filtering of a filter trained offline.

[0373] iv. In one example, this stage could be filtering using an online-trained filter.

[0374] General Example

[0375] 7. In the above examples, a video unit can refer to a sequence, picture, subpicture, strip, slice, codec tree unit (CTU), CTU row or CTU group, codec unit (CU), prediction unit (PU), transform unit (TU), codec tree block (CTB), codec block (CB), prediction block (PB), transform block (TB), or any other region containing more than one luminance or chrominance sample or pixel.

[0376] 8. Whether and / or how the methods disclosed above can be applied can be transmitted via signaling at the sequence level, picture group level, picture level, stripe level, or slice group level, such as in the sequence header, picture header, SPS, VPS, DPS, decoding capability information (DCI), PPS, APS, stripe header, or slice group header.

[0377] 9. Whether and / or how to apply the above methods may depend on the following information:

[0378] a. Messages transmitted via signals in DPS, SPS, VPS, PPS, APS, image header, strip header, slice header, codec tree unit (CTU), codec unit (CU), CTU line, CTU group, TU, PU block, or video codec unit.

[0379] b. Location of CU, PU, ​​TU, block or video codec unit

[0380] c. Block dimensions of the current block and / or its neighboring blocks

[0381] d. Block shape of the current block and / or its neighboring blocks

[0382] e. The encoding / decoding mode of the block, such as IBC or non-IBC inter-frame mode or non-IBC sub-block mode.

[0383] f. Indication of color format (e.g., 4:2:0, 4:4:4)

[0384] g. Encoder / decoder tree structure

[0385] h. Strip or slice type and / or image type

[0386] i. Color components (e.g., can be applied only to the chromaticity component or the luminance component)

[0387] j. Time-domain layer ID

[0388] k. Standard grade, level, or tier

[0389] 6. Examples

[0390] Encoding and decoding tree block filtering process for brightness-related side information

[0391] - The variables clipLeftPos, clipRightPos, clipTopPos, clipBottomPos, clipTopLeftFlag, and clipBotRightFlag (e.g., N = 4) are derived by calling the loop filter boundary position derivation process that takes (xCtb, yCtb), (x, y), and the variable vbOffset set to N as input.

[0392] - By calling (xCtb, yCtb), (h x + i , v y + j The loop filter side information sample filling process, using clipLeftPos, clipRightPos, clipTopPos, clipBottomPos, clipTopLeftFlag, and clipBotRightFlag as inputs, modifies the variable h. x + i and v y + j .

[0393] The encoding / decoding tree block filtering process for chroma-related edge information

[0394] - By calling (xCtbC) SubWidthC, yCtbC SubHeightC), (x) SubWidthC, y SubHeightC) and set it to equal 2 The variable vbOffset of SubHeightC is used as the input to derive the loop filter boundary position derivation process to derive the variables clipLeftPos, clipRightPos, clipTopPos, clipBottomPos, clipTopLeftFlag, and clipBotRightFlag.

[0395] - By calling (xCtbC) SubWidthC, yCtbC SubHeightC, (hx + i, vy + j), and variables isChroma, clipLeftPos, clipRightPos, clipTopPos, clipBottomPos, clipTopLeftFlag, and clipBotRightFlag, set to 1, are used as inputs to the loop filter side information sample filling process to modify variables hx + i and vy + j.

[0396] Derivation of the boundary position of the loop filter

[0397] The input to this process is:

[0398] - Luminance position (xCtb, yCtb), which specifies the position of the top-left sample of the current luminance codec block relative to the top-left sample of the current image.

[0399] - Luminance position (x, y), which specifies the position of the current sample relative to the upper left sample of the current luminance codec block.

[0400] - The variable vbOffset specifies the offset of the virtual boundary of the loop filter.

[0401] The variable clipTopPos has been modified as follows:

[0402] - If y - (CtbSizeY - vbOffset) is greater than or equal to 0, then the variable clipTopPos is set to equal to yCtb + CtbSizeY - vbOffset.

[0403] - Otherwise, if VirtualBoundariesPresentFlag equals 1, and for any n = 0..NumHorVirtualBoundaries - 1, yCtb + y - VirtualBoundaryPosY[n] is greater than or equal to 0 and less than (vbOffset >> 1) + 1, then the following applies:

[0404] clipTopPos = VirtualBoundaryPosY[ n ]

[0405] Otherwise, if y is less than (vbOffset >> 1) + 1, and one or more of the following conditions are true, then the variable clipTopPos is set to equal yCtb:

[0406] - The top boundary of the current codec tree block is the top boundary of the slice, and pps_loop_filter_across_tiles_enabled_flag is equal to 0.

[0407] - The top boundary of the current codec tree block is the top boundary of the slice, and pps_loop_filter_across_slices_enabled_flag is equal to 0.

[0408] - The top boundary of the current codec tree block is the top boundary of the subpic, and sps_loop_filter_across_subpic_enabled_flag[CurSubpicIdx] equals 0.

[0409] The variable clipBottomPos has been modified as follows:

[0410] - If VirtualBoundariesPresentFlag equals 1, VirtualBoundaryPosY[n] is not equal to pps_pic_height_in_luma_samples - 1 or 0, and for any n = 0..NumHorVirtualBoundaries - 1, VirtualBoundaryPosY[n] - yCtb - y is greater than 0 and less than vbOffset + 1, then the following applies:

[0411] clipBottomPos = VirtualBoundaryPosY[ n ]

[0412] Otherwise, if CtbSizeY - vbOffset - y is greater than 0 and less than vbOffset + 1, the variable clipBottomPos is set to equal yCtb + CtbSizeY - vbOffset.

[0413] Otherwise, if CtbSizeY - y is less than vbOffset + 1, and one or more of the following conditions are true, then the variable clipBottomPos is set to equal yCtb + CtbSizeY:

[0414] - The bottom boundary of the current codec tree block is the bottom boundary of the tile, and pps_loop_filter_across_tiles_enabled_flag is equal to 0.

[0415] - The bottom boundary of the current codec tree block is the bottom boundary of the slice, and pps_loop_filter_across_slices_enabled_flag is equal to 0.

[0416] - The bottom boundary of the current codec tree block is the bottom boundary of the subpic, and sps_loop_filter_across_subpic_enabled_flag[CurSubpicIdx] equals 0.

[0417] Loop filter side information sample filling process

[0418] The input to this process is:

[0419] - Luminance position (xCtb, yCtb), which specifies the position of the top-left sample of the current luminance codec block relative to the top-left sample of the current image.

[0420] - Brightness position (x, y), which specifies the position of neighboring samples relative to the top-left sample of the current image.

[0421] - The isChroma flag specifies whether a color component is a chromaticity component.

[0422] - Left vertical boundary position clipLeftPos,

[0423] - Right vertical boundary position clipRightPos

[0424] - The upper horizontal boundary position is clipTopPos.

[0425] - The lower horizontal boundary position is clipBottomPos.

[0426] - The top left border marker, clipTopLeftFlag,

[0427] - The bottom right border marker is clipBotRightFlag.

[0428] The output of this process is:

[0429] - Modified brightness position (x, y), which specifies the position of neighboring samples relative to the top-left sample of the current image.

[0430] Cross-component filtering process of side information

[0431] - By calling (xCtbC) SubWidthC, yCtbC SubHeightC), (x) SubWidthC, y The loop filter boundary position derivation process, with SubHeightC and the variable vbOffset set to equal N as input, derives the variables clipLeftPos, clipRightPos, clipTopPos, clipBottomPos, clipTopLeftFlag, and clipBotRightFlag (e.g., N = 4).

[0432] By calling (xCtbC) SubWidthC, yCtbC SubHeightC), (h) x + i , v y + j The variable h is modified by filling in the loop filter side information samples with variables isChroma, clipLeftPos, clipRightPos, clipTopPos, clipBottomPos, clipTopLeftFlag, and clipBotRightFlag, which are set to 0. x + i and v y + j .

[0433] Figure 13 This is a block diagram illustrating an example video processing system 4000 in which various techniques disclosed herein may be implemented. Various implementations may include some or all of the components of system 4000. System 4000 may include an input 4002 for receiving video content. The video content may be received in a raw or uncompressed format, such as 8 or 10-bit multi-component pixel values, or in a compressed or encoded format. Input 4002 may represent a network interface, a peripheral bus interface, or a storage interface. Examples of network interfaces include wired interfaces (such as Ethernet, Passive Optical Networking (PON), etc.) and wireless interfaces (such as Wi-Fi or cellular interfaces).

[0434] System 4000 may include an encoding component 4004 capable of implementing the various encoding / decoding or encoding methods described in this document. Encoding component 4004 can reduce the average bit rate from the video input 4002 to the output of encoding component 4004 to produce an encoded representation of the video. Encoding techniques are therefore sometimes referred to as video compression or video transcoding techniques. The output of encoding component 4004 may be stored or transmitted via a communication connection such as that represented by component 4006. The bitstream (or encoded) representation of the video received at input 4002, whether stored or transmitted via communication, may be used by component 4008 to generate pixel values ​​or displayable video that is sent to display interface 4010. The process of generating user-visible video from the bitstream representation is sometimes referred to as video decompression. Furthermore, although some video processing operations are referred to as “encoding” operations or tools, it is understood that encoding tools or operations are used by the encoder, and the corresponding decoding tools or operations that reverse the encoded result will be performed by the decoder.

[0435] Examples of peripheral bus interfaces or display interfaces may include Universal Serial Bus (USB), High Definition Multimedia Interface (HDMI), or DisplayPort. Examples of storage interfaces include Serial Advanced Technology Attachment (SATA), Peripheral Component Interconnect (PCI), and Integrated Drive Electronic Devices (IDE) interfaces. The technologies described in this document can be found in a variety of electronic devices, such as mobile phones, laptops, smartphones, or other devices capable of performing digital data processing and / or video display.

[0436] Figure 14 This is a block diagram of an example video processing apparatus 4100. Apparatus 4100 can be used to implement one or more methods described herein. Apparatus 4100 can be embodied in a smartphone, tablet, computer, Internet of Things (IoT) receiver, etc. Apparatus 4100 may include one or more processors 4102, one or more memories 4104, and video processing circuitry 4106. The processors 4102(s) may be configured to implement one or more methods described herein. The memories 4104(s) may be used to store data and code used to implement the methods and techniques described herein. The video processing circuitry 4106 may be used to implement some of the techniques described herein in hardware circuitry. In some embodiments, the video processing circuitry 4106 may be at least partially included in the processor 4102, for example, a graphics coprocessor.

[0437] Figure 15This is a flowchart of an example method 4200 for video processing. Method 4200 includes: in step 4202, determining the use of side information in a loop filter based on whether samples associated with the side information are at boundaries. In step 4204, performing a conversion between visual media data and a bitstream based on the loop filter. Depending on the example, the conversion in step 4204 may include encoding at an encoder or decoding at a decoder.

[0438] It should be noted that method 4200 can be implemented in an apparatus for processing video data, including a processor and a non-transitory memory having instructions thereon, such as a video encoder 4400, a video decoder 4500, and / or an encoder 4600. In this case, the instructions cause the processor to execute method 4200 when executed by the processor. Furthermore, method 4200 can be executed by a non-transitory computer-readable medium including a computer program product for use by a video codec device. The computer program product includes computer-executable instructions stored on the non-transitory computer-readable medium, such that when the computer-executable instructions are executed by a processor, the video codec device executes method 4200.

[0439] Figure 16 This is a block diagram illustrating an example video encoding / decoding system 4300 from which the techniques of this disclosure can be utilized. The video encoding / decoding system 4300 may include a source device 4310 and a target device 4320. The source device 4310 generates encoded video data, and this source device 4310 may be referred to as a video encoding device. The target device 4320 can decode the encoded video data generated by the source device 4310, and this target device 4320 may be referred to as a video decoding device.

[0440] Source device 4310 may include video source 4312, video encoder 4314, and input / output (I / O) interface 4316. Video source 4312 may include sources such as video capture devices, interfaces for receiving video data from video content providers, and / or computer graphics systems for generating video data, or combinations thereof. Video data may include one or more pictures. Video encoder 4314 encodes the video data from video source 4312 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 pictures and associated data. Codec pictures are codec representations of pictures. Associated data may include sequence parameter sets, picture parameter sets, and other syntax structures. I / O interface 4316 may include a modulator / demodulator (modem) and / or a transmitter. Encoded video data may be transmitted directly to target device 4320 via network 4330 through I / O interface 4316. Encoded video data may also be stored on storage medium / server 4340 for access by target device 4320.

[0441] Target device 4320 may include I / O interface 4326, video decoder 4324, and display device 4322. I / O interface 4326 may include a receiver and / or a modem. I / O interface 4326 may acquire encoded video data from source device 4310 or storage medium / server 4340. Video decoder 4324 may decode the encoded video data. Display device 4322 may display the decoded video data to a user. Display device 4322 may be integrated with target device 4320 or may be external to target device 4320, wherein target device 4320 may be configured to interface with an external display device.

[0442] The video encoder 4314 and the video decoder 4324 can operate according to video compression standards, such as the High Efficiency Video Codec (HEVC) standard, the Multi-Functional Video Codec (VVM) standard, and other existing and / or further standards.

[0443] Figure 17 This is a block diagram illustrating an example of a video encoder 4400, which can be... Figure 16 The system 4300 shown includes a video encoder 4314. The video encoder 4400 can be configured to perform any or all of the techniques disclosed herein. The video encoder 4400 includes multiple functional components. The techniques described in this disclosure can be shared among the various components of the video encoder 4400. In some examples, a processor can be configured to perform any or all of the techniques described in this disclosure.

[0444] The functional components of the video encoder 4400 may include a segmentation unit 4401, a prediction unit 4402 (which may include a mode selection unit 4403, a motion estimation unit 4404, a motion compensation unit 4405, and an intra-frame prediction unit 4406), a residual generation unit 4407, a transform processing unit 4408, a quantization unit 4409, an inverse quantization unit 4410, an inverse transform unit 4411, a reconstruction unit 4412, a buffer 4413, and an entropy coding unit 4414.

[0445] In other examples, the video encoder 4400 may include more, fewer, or different functional components. In one example, the prediction unit 4402 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 in which the current video block is located.

[0446] Furthermore, some components such as the motion estimation unit 4404 and the motion compensation unit 4405 can be highly integrated, but for illustrative purposes, these components are represented separately in the example of the video encoder 4400.

[0447] The segmentation unit 4401 can segment an image into one or more video blocks. The video encoder 4400 and the video decoder 4500 can support various video block sizes.

[0448] The mode selection unit 4403 can select one of several encoding / decoding modes (intra-frame encoding / decoding or inter-frame encoding / decoding), for example, based on error results, and provide the resulting intra-frame or inter-frame encoded / decoded block to the residual generation unit 4407 to generate residual block data, and to the reconstruction unit 4412 to reconstruct the coded block for use as a reference image. In some examples, the mode selection unit 4403 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 4403 can also select a resolution for the block based on motion vectors (e.g., sub-pixel precision or integer pixel precision).

[0449] To perform inter-frame prediction on the current video block, motion estimation unit 4404 can generate motion information for the current video block by comparing one or more reference frames from buffer 4413 with the current video block. Motion compensation unit 4405 can determine the predicted video block for the current video block based on the motion information and decoded samples of images from buffer 4413 other than the image associated with the current video block.

[0450] The motion estimation unit 4404 and the motion compensation unit 4405 can perform different operations on the current video block, for example, depending on whether the current video block is in an I-band, P-band, or B-band.

[0451] In some examples, motion estimation unit 4404 can perform unidirectional prediction on the current video block, and can search for a reference video block for the current video block in the reference images of list 0 or list 1. Motion estimation unit 4404 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 4404 can output the reference index, prediction direction indicator, and motion vector as motion information for the current video block. Motion compensation unit 4405 can generate a predicted video block for the current block based on the reference video block indicated by the motion information of the current video block.

[0452] In other examples, motion estimation unit 4404 can perform bidirectional prediction on the current video block. Motion estimation unit 4404 can search for a reference video block for the current video block in the reference images in list 0, and can also search for another reference video block for the current video block in the reference images in list 1. Motion estimation unit 4404 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 4404 can output the reference index and motion vector of the current video block as motion information for the current video block. Motion compensation unit 4405 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.

[0453] In some examples, the motion estimation unit 4404 can output a complete set of motion information for use in the decoder's decoding process. In some examples, the motion estimation unit 4404 may not output a complete set of motion information for the current video. Instead, the motion estimation unit 4404 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 4404 may determine that the motion information of the current video block is sufficiently similar to the motion information of neighboring video blocks.

[0454] In one example, the motion estimation unit 4404 may indicate a value to the video decoder 4500 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.

[0455] In another example, motion estimation unit 4404 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 4500 may use the motion vector of the indicated video block and the motion vector difference to determine the motion vector of the current video block.

[0456] As discussed above, the video encoder 4400 can transmit motion vectors via signaling in a predictive manner. Two examples of predictive signaling techniques that can be implemented by the video encoder 4400 include Advanced Motion Vector Prediction (AMVP) and Merge Pattern Signaling.

[0457] Intra-prediction unit 4406 can perform intra-prediction on the current video block. When intra-prediction unit 4406 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.

[0458] The residual generation unit 4407 can generate residual data for the current video block by subtracting (or more) predicted video blocks from the current video block. The residual data for the current video block may include residual video blocks corresponding to different sample components of the samples in the current video block.

[0459] In other examples, such as in skip mode, there may be no residual data for the current video block, and the residual generation unit 4407 may not perform subtraction operations.

[0460] The transform processing unit 4408 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.

[0461] After the transform processing unit 4408 generates a transform coefficient video block associated with the current video block, the quantization unit 4409 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.

[0462] The inverse quantization unit 4410 and the inverse transform unit 4411 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 4412 can add the reconstructed residual video block to the corresponding sample points of one or more predicted video blocks generated by the prediction unit 4402 to generate a reconstructed video block associated with the current block for storage in the buffer 4413.

[0463] After the video block is reconstructed by reconstruction unit 4412, a loop filtering operation can be performed to reduce video block artifacts in the video block.

[0464] Entropy encoding unit 4414 can receive data from other functional components of video encoder 4400. When entropy encoding unit 4414 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.

[0465] Figure 18 This is a block diagram illustrating an example of a video decoder 4500, which can be... Figure 16 The system 4300 shown includes a video decoder 4324. The video decoder 4500 can be configured to perform any or all of the techniques disclosed herein. In the example shown, the video decoder 4500 includes multiple functional components. The techniques described in this disclosure can be shared among the various components of the video decoder 4500. In some examples, a processor can be configured to perform any or all of the techniques described in this disclosure.

[0466] In the example shown, the video decoder 4500 includes an entropy decoding unit 4501, a motion compensation unit 4502, an intra-frame prediction unit 4503, an inverse quantization unit 4504, an inverse transform unit 4505, a reconstruction unit 4506, and a buffer 4507. In some examples, the video decoder 4500 can perform a decoding process that is generally contrasted with the encoding process described with respect to the video encoder 4400.

[0467] The entropy decoding unit 4501 can retrieve the encoded bitstream. The encoded bitstream may include entropy-encoded video data (e.g., encoded blocks of video data). The entropy decoding unit 4501 can decode the entropy-encoded video data, and based on the entropy-decoded video data, the motion compensation unit 4502 can determine motion information, including motion vectors, motion vector precision, reference image list index, and other motion information. The motion compensation unit 4502 can determine this information, for example, by executing AMVP and Merge modes.

[0468] The motion compensation unit 4502 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.

[0469] The motion compensation unit 4502 can use interpolation filters, such as those used by the video encoder 4400 during the encoding of a video block, to calculate sub-integer pixels for a reference block. The motion compensation unit 4502 can determine the interpolation filter used by the video encoder 4400 based on the received syntax information, and the motion compensation unit 4502 can use the interpolation filter to generate a prediction block.

[0470] The motion compensation unit 4502 may use some syntax information to determine the size of the blocks of (multiple) frames and / or (multiple) stripes used to encode the encoded video sequence, segmentation information describing how each macroblock of the picture of the encoded video sequence is segmented, a mode indicating how each segment is encoded, one or more reference frames (and a list of reference frames) for each inter-frame codec block, and other information for decoding the encoded video sequence.

[0471] Intra-prediction unit 4503 can use, for example, an intra-prediction mode received in the bitstream to form prediction blocks from spatially adjacent blocks. Inverse quantization unit 4504 performs inverse quantization (i.e., dequantization) on the quantized video block coefficients provided in the bitstream and decoded by entropy decoding unit 4501. Inverse transform unit 4505 applies the inverse transform.

[0472] The reconstruction unit 4506 can add the residual block to the corresponding predicted block generated by the motion compensation unit 4502 or the intra-frame prediction unit 4503 to form a decoded block. If necessary, a deblocking filter can also be used to filter the decoded block to remove block artifacts. The decoded video block is then stored in a buffer 4507, which provides a reference block for subsequent motion compensation / intra-frame prediction and also generates decoded video for presentation on a display device.

[0473] Figure 19 This is a schematic diagram of the example encoder 4600. Encoder 4600 is suitable for implementing VVC techniques. Encoder 4600 includes three loop filters: a deblocking filter (DF) 4602, a sample adaptive compensation (SAO) 4604, and an adaptive loop filter (ALF) 4606. Unlike DF 4602, which uses predefined filters, SAO 4604 and ALF 4606 utilize the original samples of the current image, respectively, by adding an offset and by applying a finite impulse response (FIR) filter, and by utilizing the encoded / decoded side information through signal transmission offset and filter coefficients to reduce the mean square error between the original and reconstructed samples. ALF 4606 is located in the final processing stage of each image and can be considered as a tool for attempting to capture and repair artifacts caused by previous stages.

[0474] The encoder 4600 also includes an intra-frame prediction component 4608 and a motion estimation / compensation (ME / MC) component 4610 configured to receive input video. The intra-frame prediction component 4608 is configured to perform intra-frame prediction, while the ME / MC component 4610 is configured to perform inter-frame prediction using reference images obtained from a reference image buffer 4612. Residual blocks from inter-frame or intra-frame prediction are fed into a transform (T) component 4614 and a quantization (Q) component 4616 to generate quantized residual transform coefficients, which are then fed into an entropy coding component 4618. The entropy coding component 4618 entropy-codes the prediction results and the quantized transform coefficients and transmits them to a video decoder (not shown). The quantized components output from the quantization component 4616 can be fed into an inverse quantization (IQ) component 4620, an inverse transform component 4622, and a reconstruction (REC) component 4624. REC component 4624 is able to output images to DF 4602, SAO 4604 and ALF4606 for filtering before these images are stored in reference image buffer 4612.

[0475] Figure 20This is a flowchart of another example method 4700 for video processing. Method 4700 includes: in step 4702, determining the use of side information in a loop filter by applying line buffer constraints to the side information. In step 4704, performing a conversion between visual media data and a bitstream based on the loop filter. Depending on the example, the conversion in step 4704 may include encoding at an encoder or decoding at a decoder.

[0476] It should be noted that method 4700 can be implemented in an apparatus for processing video data, including a processor and a non-transitory memory having instructions thereon, such as a video encoder 4400, a video decoder 4500, and / or an encoder 4600. In this case, the instructions, when executed by the processor, cause the processor to perform method 4700. Furthermore, method 4700 can be executed by a non-transitory computer-readable medium including a computer program product for use by a video codec device. The computer program product includes computer-executable instructions stored on the non-transitory computer-readable medium, causing the video codec device to perform method 4700 when executed by a processor.

[0477] The following is a list of some preferred solutions.

[0478] The following solutions illustrate examples of the techniques discussed in this article.

[0479] 1. A method for processing video data, comprising: determining the use of side information in a loop filter based on whether samples associated with side information are at boundaries; and performing a conversion between visual media data and a bitstream based on the loop filter.

[0480] 2. The method according to Solution 1, wherein the boundary is a codec tree unit (CTU) boundary, a CTU row boundary, or a virtual boundary.

[0481] 3. The method described according to solution 1 or 2, wherein the sample points at the boundary are referred to as being at the row cache.

[0482] 4. The method according to any one of solutions 1-3, wherein the use of the side information is the same as the use of reconstructed samples at the line buffer of one or more loop filters.

[0483] 5. The method according to any one of solutions 1-4, wherein the loop filter is a deblocking filter (DBF), sample adaptive compensation (SAO), cross-component SAO (CCSAO), adaptive loop filter (ALF) luminance, ALF chrominance, cross-component ALF (CCALF), bilateral filter (BIF), BIF chrominance, or a variant thereof.

[0484] 6. The method according to any one of solutions 1-5, wherein the row cache limit for the side information is applied to different stages in one or more loop filters.

[0485] 7. The method according to any one of solutions 1-6, wherein the row cache restriction on the edge information is applied to a filtering stage, a classification stage, or both the filtering stage and the classification stage.

[0486] 8. The method according to any one of solutions 1-7, wherein the edge information refers to a predicted sample, a residual sample, a reconstructed sample before a specific loop filter, a reconstructed sample after a specific loop filter, or an intermediate value within a specific loop filter.

[0487] 9. The method according to any one of solutions 1-8, wherein the intermediate value refers to the output of an offline filter or an online filter of ALF or CCALF, or the input used to generate the intermediate value refers to the reconstruction before DBF, the reconstruction before ALF, the predicted sample, or the residual sample.

[0488] 10. The method according to any one of solutions 1-9, wherein the edge information refers to encoding / decoding information including prediction mode, boundary strength, or quantization parameter (QP).

[0489] 11. The method according to any one of solutions 1-10, wherein the filling process of the unavailable sample points of the edge information at the row cache is the same as the filling process of the unavailable sample points of the reconstructed sample points, or wherein the filling method is repeated filling or mirror filling.

[0490] 12. The method according to any one of solutions 1-11, wherein the use of the side information differs from the use of reconstructed samples at the line buffer of one or more loop filters, or wherein the number of lines (N1) used in the line buffer of the side information differs from the number of second lines (N2) used in the line buffer of the reconstructed samples, wherein N1<N2、N1> N2 or N1=0, or the edge information is not stored in the row cache, or the filling process for the unavailable samples of the edge information in the row cache is different from the filling process for the unavailable samples of the reconstructed samples.

[0491] 13. The method according to any one of solutions 1-12, wherein the edge information comes from one or more color components, and wherein the color components include luminance (Y), blue chromatic aberration (Cb), or red chromatic aberration (Cr) in the YCbCr color space, green (G), blue (B), or red (R) in the GBR color space, or any other color space used in video encoding / decoding.

[0492] 14. The method according to any one of solutions 1-13, wherein ALF chroma and CCALF are executed in parallel, or wherein a first offset (O1) is generated from ALF chroma and a second offset (O2) is generated from CCALF, O1 and O2 are first added to the chroma sample and a clipping operation is performed according to R' = clip(R + O1 + O2), where R represents the current chroma sample, R' represents the sample filtered by ALF chroma and CCALF, and clip() represents the clipping operation, or wherein the clipping operation is performed once on ALF chroma and CCALF.

[0493] 15. The method according to any one of solutions 1-14, wherein the method is used for post-processing or pre-processing.

[0494] 16. The method according to any one of solutions 1-15, wherein the luminance loop filter boundary is derived for luminance-related edge information and the chrominance loop filter boundary is derived for chrominance-related edge information, wherein the luminance loop filter boundary is different from the chrominance loop filter boundary.

[0495] 17. The method according to any one of solutions 1-16, wherein the luminance loop filter boundary is derived and used for luminance-related edge information used in DBF, BIF, SAO, CCSAO, ALF, or CCALF, or wherein the chrominance loop filter boundary is derived and used for chrominance-related edge information used in DBF, BIF, SAO, CCSAO, ALF, or CCALF, or wherein the chrominance loop filter boundary depends on the color format or filtering process, or wherein the chrominance loop filter boundary is derived in different ways for 4:2:0 color format, 4:2:2 color format, and 4:4:4 color format, or wherein the luminance loop filter boundary position is a top boundary position, a bottom boundary position, a left boundary position, or a right boundary position.

[0496] 18. The method according to any one of solutions 1-17, wherein the derivation of the luminance loop filter boundary position depends on a variable vbOffset specifying the offset of the loop filter virtual boundary or the distance between the loop filter virtual boundary and the bottom boundary of the current CTB, or a variable M specifying the offset relative to the top boundary of the current CTB, wherein the luminance position of the current edge information sample relative to the upper left sample of the current luminance CTB is represented as (x, y), the luminance position of the upper left sample of the current luminance CTB relative to the upper left sample of the current image is (xCtb, yCtb), and the size of the current luminance CTB is represented as CtbSizeY, or wherein the top boundary position is set to equal to yCtb + CtbSizeY - vbOffset when y - (CtbSizeY - vbOffset) is greater than or equal to 0. vbOffset, or where the top boundary of the current CTB is the top boundary of a slice, strip, or sub-image, or the loop filter across a slice, strip, or sub-image is disabled, and the top boundary position is set to equal yCtb when y is less than M, or where the bottom boundary position is set to equal yCtb + CtbSizeY - vbOffset when CtbSizeY - y is greater than 0 and less than N, or where the bottom boundary of the current CTB is the bottom boundary of a slice, strip, or sub-image, and the loop filter across a slice, strip, or sub-image is disabled, and the bottom boundary position is set to equal yCtb + CtbSizeY when CtbSizeY - y is less than L.

[0497] 19. The method according to any one of solutions 1-18, wherein the chroma loop filter boundary used in the 4:2:0 format is derived in the same manner as the luma loop filter boundary, or wherein, when the chroma format is 4:2:0, the same value t of vbOffset is used for luma and chroma related edge information during the derivation at the top or bottom boundary position, or wherein vbOffset is an integer including 4, or wherein, when the chroma format is 4:2:0, the same values ​​of M, N, and L are used for luma and chroma related edge information during the derivation at the top or bottom boundary position, or wherein M, N, and L are integers including M = 3, N = 5, and L = 5.

[0498] 20. The method according to any one of solutions 1-19, wherein the chroma loop filter boundary and the luma loop filter boundary used in the 4:2:2 or 4:4:4 chroma format are derived in different ways, or wherein when the chroma format is 4:2:2 or 4:4:4, different values ​​of vbOffset are used for luma and chroma-related side information during the derivation at the top boundary position or the bottom boundary position, or wherein vbOffset1 is used for chroma-related side information and vbOffset2 is used for luma-related side information, wherein vbOffset1 is not equal to vbOffset2, or wherein vbOffset1 = 2 and vbOffset2 = 4, or where, when the chroma format is 4:2:2 or 4:4:4, different values ​​of vbOffset are used for chroma-related edge information in the chroma format of 4:2:0 during the derivation at the top or bottom boundary position, or where, when the chroma format is 4:2:2 or 4:4:4, different values ​​of M, N, and L are used for luminance and chroma-related edge information during the derivation at the top or bottom boundary position, or where M1, N1, and L1 are used for chroma-related edge information, and M2, N2, and L2 are used for luminance-related edge information, where M1 is not equal to M2, N1 is not equal to N2, and L1 is not equal to L2, or where M1 = 2, M1 = 3, L1 = 3, and M2 = 3, N2 = 5, and L2 = 5.

[0499] 21. The method according to any one of solutions 1-20, wherein the edge information samples are filled at boundary locations, or wherein luminance-related edge information samples are filled when a luminance boundary location is encountered, or wherein chrominance-related edge information samples are filled when a chrominance boundary location is encountered, or wherein the edge information samples are filled at different stages of the loop filter, or wherein the stage is classification of an offline-trained filter, classification of an online-trained filter, filtering of an offline-trained filter, or filtering of an online-trained filter.

[0500] 22. The method according to any one of solutions 1-21, wherein the loop filter is applied to a video unit, and wherein the video unit is a color component, sub-picture, strip, slice, CTU, CTU line, CTU group, CU, prediction unit (PU), transform unit (TU), codec tree block (CTB), codec block (CB), prediction block (PB), transform block (TB), block, sub-block of block, sub-region within block, or any other region containing more than one sample point or pixel.

[0501] 23. The method according to any one of solutions 1-22, wherein the use of the method is transmitted via signal at the sequence level, picture group level, picture level, strip level or slice group level, including in the sequence header, picture header, sequence parameter set (SPS), video parameter set (VPS), decoding parameter set (DPS), decoding capability information (DCI), picture parameter set (PPS), adaptive parameter set (APS), strip header or slice group header.

[0502] 24. The method according to any one of solutions 1-23, wherein the application of the loop filter depends on: messages transmitted via signals in the DPS, SPS, VPS, PPS, APS, picture header, strip header, slice header, codec tree unit (CTU), codec unit (CU), CTU row, CTU group, TU, PU block, or video codec unit; the position of the CU, PU, ​​TU, block, or video codec unit; the block dimension of the current block or neighboring blocks; the block shape of the current block and neighboring blocks; the codec mode of the block, including IBC, non-IBC inter-frame mode, or non-IBC sub-block mode; an indication of a color format including 4:2:0 or 4:4:4; the codec tree structure; the strip group type, slice group type, or picture type; the color component applied only to the chroma component or the luminance component; the temporal layer ID; or the standard grade, level, or layer.

[0503] 25. The method according to any one of solutions 1-24, wherein the conversion includes encoding the visual media data into the bitstream.

[0504] 26. The method according to any one of solutions 1-24, wherein the conversion includes decoding the visual media data from the bitstream.

[0505] 27. An apparatus for processing video data, comprising: 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 any one of solutions 1-26.

[0506] 28. A non-transitory computer-readable medium comprising a computer program product for use by a video codec apparatus, the computer program product including computer-executable instructions stored on the non-transitory computer-readable medium such that when the computer-executable instructions are executed by a processor, the video codec apparatus performs the method according to any one of solutions 1-26.

[0507] 29. A non-transitory computer-readable recording medium storing a bitstream of video generated by a method performed by a video processing apparatus, wherein the method includes: determining the use of the side information in a loop filter based on whether samples associated with side information are at boundaries; and generating the bitstream based on the determination.

[0508] 30. A method for storing a bitstream of video, comprising: determining the use of side information in a loop filter based on whether samples associated with side information are at boundaries; generating a bitstream based on the determination; and storing the bitstream in a non-transitory computer-readable recording medium.

[0509] 31. A method, apparatus or system described in this document.

[0510] The following solutions illustrate further examples of the techniques discussed in this article.

[0511] 1. A method for processing video data, comprising: determining the use of the side information in a loop filter by applying a line buffer constraint to the side information; and performing a conversion between visual media data and a bitstream based on the loop filter.

[0512] 2. The method according to Solution 1, wherein the row cache limit on the edge information is applied to the filtering stage.

[0513] 3. The method according to solution 1 or 2, wherein the row caching restriction on the edge information is applied in the classification phase.

[0514] 4. The method according to any one of solutions 1-3, wherein the use of the side information is the same as the use of reconstructed samples at the line buffer of one or more loop filters.

[0515] 5. The method according to any one of solutions 1-4, wherein the loop filter is a deblocking filter (DBF), sample adaptive compensation (SAO), cross-component SAO (CCSAO), adaptive loop filter (ALF) luminance, ALF chrominance, cross-component ALF (CCALF), bilateral filter (BIF), BIF chrominance, or a variant thereof.

[0516] 6. The method according to any one of solutions 1-5, wherein the side information is an intermediate value within the loop filter, and wherein the intermediate value is the output of the offline filter of the ALF, the output of the online filter of the ALF, the output of the online filter of the CCALF, or the output of the online filter of the CCALF.

[0517] 7. The method according to any one of solutions 1-6, wherein the input for generating intermediate values ​​within the loop filter is either reconstructed samples prior to the DBF or residual samples.

[0518] 8. The method according to any one of solutions 1-7, wherein the edge information includes encoding / decoding information, prediction mode, boundary strength, or quantization parameter (QP).

[0519] 9. The method according to any one of solutions 1-8, wherein a fill is applied to the unavailable sample points of the edge information, and wherein the fill includes a mirror fill or a symmetrical fill.

[0520] 10. The method according to any one of solutions 1-9, wherein the number of rows (N1) used in the row cache of the edge information is different from the second number (N2) used in the row cache of the reconstructed samples, wherein N1 <N2。

[0521] 11. The method according to any one of solutions 1-10, wherein the edge information is obtained from one or more color components, the one or more color components including luminance (Y), blue chromatic aberration (Cb), or red chromatic aberration (Cr) in the YCbCr color space.

[0522] 12. The method according to any one of solutions 1-11, wherein the luminance loop filter boundary is derived and used for luminance-related side information used in DBF, BIF, SAO, CCSAO, ALF, or CCALF.

[0523] 13. The method according to any one of solutions 1-12, wherein the chromaticity loop filter boundary is derived and used for chromaticity-related edge information used in DBF, BIF, SAO, CCSAO, ALF or CCALF.

[0524] 14. The method according to any one of solutions 1-13, wherein the derivation of the luminance loop filter boundary position depends on a virtual boundary offset (vbOffset) variable that specifies the offset of the loop filter virtual boundary or the distance between the loop filter virtual boundary and the bottom boundary of the current codec tree block (CTB), and wherein the derivation of the luminance loop filter boundary position depends on a variable M that specifies the offset relative to the top boundary of the current CTB, wherein the luminance position of the current edge information sample relative to the upper left sample of the current luminance CTB is represented as (x, y), the luminance position of the upper left sample of the current luminance CTB relative to the upper left sample of the current image is (xCtb, yCtb), and the size of the current luminance CTB is represented as CTB size Y (CtbSizeY).

[0525] 15. The method according to any one of solutions 1-14, wherein the chroma loop filter boundary used in the 4:2:0 format is derived in the same manner as the luminance loop filter boundary.

[0526] 16. The method according to any one of solutions 1-15, wherein when a brightness boundary location is encountered, brightness-related edge information samples are filled.

[0527] 17. The method according to any one of solutions 1-16, wherein when a chromaticity boundary location is encountered, chromaticity-related edge information samples are filled.

[0528] 18. The method according to any one of solutions 1-17, wherein the use of the edge information in the loop filter is determined based on whether the sample associated with the edge information is at the boundary.

[0529] 19. The method according to any one of solutions 1-18, wherein the boundary is a codec tree unit (CTU) boundary, a CTU row boundary, or a virtual boundary.

[0530] 20. The method according to any one of solutions 1-19, wherein the sample points at the boundary are referred to as being at the line buffer.

[0531] 21. The method according to any one of solutions 1-20, wherein a row cache constraint on the side information is applied to different stages in one or more loop filters.

[0532] 22. The method according to any one of solutions 1-21, wherein the row cache restriction on the edge information is applied to both the filtering stage and the classification stage.

[0533] 23. The method according to any one of solutions 1-22, wherein the edge information includes predicted samples, residual samples, reconstructed samples before a specific loop filter, reconstructed samples after a specific loop filter, or intermediate values ​​within a specific loop filter.

[0534] 24. The method according to any one of solutions 1-23, wherein the input for generating intermediate values ​​includes reconstructed or predicted samples prior to ALF.

[0535] 25. The method according to any one of solutions 1-24, wherein the padding of unavailable samples of the edge information at the row cache is the same as the padding of unavailable samples of the reconstructed samples, or wherein the padding is repeated padding or one-sided padding.

[0536] 26. The method according to any one of solutions 1-25, wherein the use of the side information differs from the use of reconstructed samples at the line buffer of one or more loop filters, or wherein the number of lines (N1) used in the line buffer of the side information differs from the second number (N2) used in the line buffer of the reconstructed samples, wherein N1>N2 or N1=0, or wherein the side information is not stored in the line buffer, or wherein the filling process for unavailable samples of the side information at the line buffer differs from the filling process for unavailable samples of the reconstructed samples.

[0537] 27. The method according to any one of solutions 1-26, wherein the edge information comes from one or more color components, and wherein the color components include green (G), blue (B), or red (R) in the GBR color space, or any other color space used in video encoding / decoding.

[0538] 28. The method according to any one of solutions 1-27, wherein ALF chroma and CCALF are executed in parallel, or wherein a first offset (O1) is generated from ALF chroma and a second offset (O2) is generated from CCALF, O1 and O2 are first added to the chroma sample and a clipping operation is performed according to R' = clip(R + O1 + O2), where R represents the current chroma sample, R' represents the sample filtered by ALF chroma and CCALF, and clip() represents the clipping operation, or wherein the clipping operation is performed once on ALF chroma and CCALF.

[0539] 29. The method according to any one of solutions 1-28, wherein the edge information is used for post-processing or pre-processing.

[0540] 30. The method according to any one of solutions 1-29, wherein the luminance loop filter boundary is derived for luminance-related edge information and the chrominance loop filter boundary is derived for chrominance-related edge information, wherein the luminance loop filter boundary is different from the chrominance loop filter boundary.

[0541] 31. The method according to any one of solutions 1-30, wherein the chroma loop filter boundary depends on the color format or filtering process, or wherein the chroma loop filter boundary is derived in different ways for 4:2:0 color format, 4:2:2 color format and 4:4:4 color format, or wherein the luminance loop filter boundary position is a top boundary position, a bottom boundary position, a left boundary position or a right boundary position.

[0542] 32. The method according to any one of solutions 1-31, wherein the top boundary position is set to equal yCtb + CtbSizeY - vbOffset when y - (CtbSizeY - vbOffset) is greater than or equal to 0, or wherein the top boundary of the current CTB is the top boundary of a slice, strip, or sub-picture, or a loop filter across slices, strips, or sub-pictures is disabled, and the top boundary position is set to equal yCtb when y is less than M, or wherein the bottom boundary position is set to equal yCtb + CtbSizeY - vbOffset when CtbSizeY - vbOffset - y is greater than 0 and less than N, or wherein the bottom boundary of the current CTB is the bottom boundary of a slice, strip, or sub-picture, and a loop filter across slices, strips, or sub-pictures is disabled, and the bottom boundary position is set to equal yCtb + CtbSizeY when CtbSizeY - y is less than L.

[0543] 33. The method according to any one of solutions 1-32, wherein when the chroma format is 4:2:0, during the derivation of the top boundary position or the bottom boundary position, the same value of vbOffset is used for the luminance and chroma-related edge information, or wherein vbOffset is an integer including 4, or wherein when the chroma format is 4:2:0, during the derivation of the top boundary position or the bottom boundary position, the same values ​​of M, N, and L are used for the luminance and chroma-related edge information, or wherein M, N, and L are integers including M = 3, N = 5, and L = 5.

[0544] 34. The method according to any one of solutions 1-33, wherein the chroma loop filter boundary and the luma loop filter boundary used in the 4:2:2 or 4:4:4 chroma format are derived in different ways, or wherein when the chroma format is 4:2:2 or 4:4:4, different values ​​of vbOffset are used for luma and chroma-related edge information during the derivation at the top boundary position or the bottom boundary position, or wherein vbOffset1 is used for chroma-related edge information and vbOffset2 is used for luma-related edge information, wherein vbOffset1 is not equal to vbOffset2, or wherein vbOffset1 = 2 and vbOffset2 = 4, or where, when the chroma format is 4:2:2 or 4:4:4, different values ​​of vbOffset are used for chroma-related edge information in the chroma format of 4:2:0 during the derivation at the top or bottom boundary position, or where, when the chroma format is 4:2:2 or 4:4:4, different values ​​of M, N, and L are used for luminance and chroma-related edge information during the derivation at the top or bottom boundary position, or where M1, N1, and L1 are used for chroma-related edge information, and M2, N2, and L2 are used for luminance-related edge information, where M1 is not equal to M2, N1 is not equal to N2, and L1 is not equal to L2, or where M1 = 2, M1 = 3, L1 = 3, and M2 = 3, N2 = 5, and L2 = 5.

[0545] 35. The method according to any one of solutions 1-34, wherein the edge information samples are filled at boundary locations, or wherein the edge information samples are filled at different stages of the loop filter, or wherein the stage is classification of an offline-trained filter, classification of an online-trained filter, filtering of an offline-trained filter, or filtering of an online-trained filter.

[0546] 36. The method according to any one of solutions 1-35, wherein the loop filter is applied to a video unit, and wherein the video unit is a color component, sub-picture, strip, slice, CTU, CTU line, CTU group, CU, prediction unit (PU), transform unit (TU), codec tree block (CTB), codec block (CB), prediction block (PB), transform block (TB), block, sub-block of block, sub-region within block, or any other region containing more than one sample point or pixel.

[0547] 37. The method according to any one of solutions 1-36, wherein the use of the side information is transmitted via signaling at the sequence level, picture group level, picture level, strip level, or slice group level, including in the sequence header, picture header, sequence parameter set (SPS), video parameter set (VPS), decoding parameter set (DPS), decoding capability information (DCI), picture parameter set (PPS), adaptive parameter set (APS), strip header, or slice group header.

[0548] 38. The method according to any one of solutions 1-37, wherein the application of the loop filter depends on: messages transmitted via signals in the DPS, SPS, VPS, PPS, APS, picture header, strip header, slice header, codec tree unit (CTU), codec unit (CU), CTU row, CTU group, TU, PU block, or video codec unit; the position of the CU, PU, ​​TU, block, or video codec unit; the block dimension of the current block or neighboring blocks; the block shape of the current block and neighboring blocks; the codec mode of the block, including IBC, non-IBC inter-frame mode, or non-IBC sub-block mode; an indication of a color format including 4:2:0 or 4:4:4; the codec tree structure; the strip group type, slice group type, or picture type; the color component applied only to the chroma component or the luminance component; the temporal layer ID; or the standard grade, level, or layer.

[0549] 39. The method according to any one of solutions 1-38, wherein the conversion includes encoding the visual media data into the bitstream.

[0550] 40. The method according to any one of solutions 1-38, wherein the conversion includes decoding the visual media data from the bitstream.

[0551] 41. An apparatus for processing video data, comprising: 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 any one of solutions 1-40.

[0552] 42. A non-transitory computer-readable medium comprising a computer program product for use by a video codec apparatus, the computer program product including computer-executable instructions stored on the non-transitory computer-readable medium such that when the computer-executable instructions are executed by a processor, the video codec apparatus performs the method according to any one of solutions 1-40.

[0553] 43. A non-transitory computer-readable recording medium storing a bitstream of video generated by a method performed by a video processing apparatus, wherein the method includes: determining the use of the side information in a loop filter by applying a line buffer constraint to the side information; and generating the bitstream based on the determination.

[0554] 44. A method for storing a bitstream of video, comprising: determining the use of side information in a loop filter by applying a line buffer constraint to side information; generating the bitstream based on the determination; and storing the bitstream in a non-transitory computer-readable recording medium.

[0555] In the described solution, the encoder conforms to the format rules by generating an encoded representation based on those rules. In the described solution, the decoder parses the syntax elements in the encoded representation using known information about their presence or absence, based on the format rules, to generate the decoded video.

[0556] In this document, the term "video processing" can refer to video encoding, video decoding, video compression, or video decompression. For example, a video compression algorithm can be applied during the conversion from the pixel representation of a video to the corresponding bitstream representation, and vice versa. For example, the bitstream representation of the current video block can correspond to bits at the same position in the bitstream defined by the syntax or bits propagated at different positions. For example, a macroblock can be encoded based on the error residual value after transformation and encoding, and can also use bits from the header and other fields in the bitstream. Furthermore, during the conversion, the decoder can resolve the bitstream based on determination, knowing whether some fields may or may not be present, as described in the solutions above. Similarly, the encoder can determine whether to include or exclude specific syntax fields and generate the encoded / decoded representation accordingly by including or excluding syntax fields from the encoded / decoded representation.

[0557] The disclosed and other solutions, examples, embodiments, modules, and functional operations described in this document can be implemented in digital electronic circuits, or in computer software, firmware, or hardware, including the structures disclosed in this document and their structural equivalents, or in combinations thereof. The disclosed and other embodiments can be implemented as one or more computer program products, i.e., one or more computer program instruction modules encoded on a computer-readable medium for execution by or control of the operation of a data processing apparatus. The computer-readable medium can be a machine-readable storage device, a machine-readable storage substrate, a storage device, a composition of substances influencing machine-readable propagation signals, or combinations thereof. The term "data processing apparatus" encompasses all means, devices, and machines for processing data, including, for example, a programmable processor, a computer, or multiple processors or computers. In addition to hardware, the apparatus may also include code that creates an execution environment for a related computer program, such as code constituting processor firmware, a protocol stack, a database management system, an operating system, or combinations thereof. Propagation signals are artificially generated signals, such as machine-generated electrical, optical, or electromagnetic signals, which are generated to encode information to be transmitted to a suitable receiver device.

[0558] Computer programs (also known as programs, software, software applications, scripts, or code) can be written in any programming language, including compiled or interpreted languages, and can be deployed in any form, including standalone programs or modules, components, subroutines, or other units suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the related program, or in multiple co-located files (e.g., a file storing one or more modules, subroutines, or code portions). A computer program can be deployed to execute on one computer or on multiple computers located at a single site or distributed across multiple sites and interconnected by a communications network.

[0559] The processing and logic flows described in this document can be executed by one or more programmable processors that execute one or more computer programs to perform functions by manipulating input data and generating outputs. The processing and logic flows can also be executed by special-purpose logic circuitry, and the devices can be implemented as special-purpose logic circuitry, such as field-programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs).

[0560] Processors suitable for executing computer programs include, for example, general-purpose and special-purpose microprocessors, and any one or more processors of any type of digital computer. Typically, a processor receives instructions and data from read-only memory or random access memory, or both. The basic components of a computer are a processor that executes instructions and one or more storage devices that store the instructions and data. Typically, a computer will also include one or more mass storage devices for storing data, such as magnetic disks, magneto-optical disks, or optical disks, or receive data from or transfer data to one or more mass storage devices via operative coupling, or both. However, a computer does not necessarily have such devices. Computer-readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media, and storage devices, including, for example, semiconductor storage devices such as erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), and flash memory devices; magnetic disks, such as internal hard disks or removable hard disks; magneto-optical disks; and compact disc read-only memory (CD-ROM) and digital versatile disc read-only memory (DVD-ROM). Processors and memory may be supplemented by or incorporated into dedicated logic circuitry.

[0561] While this patent document contains numerous details, these details should not be construed as limiting any subject matter or the scope of the claims, but rather as descriptions of features specific to particular embodiments of a particular technology. In this patent document, certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented separately in multiple embodiments, or in any suitable sub-combination. Furthermore, although features may function in certain combinations as described above, and even were originally claimed in this manner, in some cases one or more features in the claimed combination may be removed from that combination, and the claimed combination may be for sub-combinations or variations thereof.

[0562] Similarly, although operations are depicted in a specific order in the accompanying drawings, this should not be construed as requiring such operations to be performed sequentially in the specific order or sequence shown, or requiring all shown operations to be performed in order to achieve the desired result. Furthermore, the division of various system components in the embodiments described in this patent document should not be construed as requiring such division in all embodiments.

[0563] Only a few implementations and examples are described, and other implementations, improvements and variations can be made based on what is described and shown in this patent document.

[0564] When there are no intermediate components other than a line, trace, or other medium between the first and second components, the first component is directly coupled to the second component. When there are intermediate components other than a line, trace, or other medium between the first and second components, the first component is indirectly coupled to the second component. The term "coupled" and its variations include direct coupling and indirect coupling. The use of the term "about" means including a range of ±10% of the following figures, unless otherwise specified.

[0565] While several embodiments have been provided in this disclosure, it should be understood that the disclosed systems and methods may be embodied in many other specific forms without departing from the spirit or scope of this disclosure. The present examples are to be considered illustrative rather than restrictive and are not intended to be limited to the details set forth herein. For example, various elements or components may be combined or integrated into another system, or certain features may be omitted or not implemented.

[0566] Furthermore, the technologies, systems, subsystems, and methods described and illustrated as discrete or separate in the various embodiments can be combined or integrated with other systems, modules, technologies, or methods without departing from the scope of this disclosure. Other items shown or discussed as couplings may be directly connected or indirectly coupled or communicated through some interface, device, or intermediate component, whether electrically, mechanically, or otherwise. Other examples of variations, substitutions, and alterations can be identified by those skilled in the art and can be made without departing from the spirit and scope of this disclosure.

Claims

1. A method for processing video data, comprising: The use of the edge information in the loop filter is determined by applying a row cache constraint to the edge information; as well as The conversion between visual media data and bitstream is performed based on the loop filter.

2. The method as described in claim 1, wherein, The row cache limit for the edge information is applied during the filtering phase.

3. The method as described in claim 1 or 2, wherein, The row caching limit for the edge information is applied during the classification phase.

4. The method according to any one of claims 1-3, wherein, The use of the side information is the same as the use of reconstructed samples at the line buffer of one or more loop filters.

5. The method according to any one of claims 1-4, wherein, The loop filter is a deblocking filter (DBF), sample adaptive compensation (SAO), cross-component SAO (CCSAO), adaptive loop filter (ALF) luminance, ALF chrominance, cross-component ALF (CCALF), bilateral filter (BIF), BIF chrominance, or a variant thereof.

6. The method according to any one of claims 1-5, wherein, The edge information is an intermediate value within the loop filter, and the intermediate value is the output of the offline filter of the ALF, the output of the online filter of the ALF, the output of the online filter of the CCALF, or the output of the online filter of the CCALF.

7. The method according to any one of claims 1-6, wherein, The input used to generate intermediate values ​​within the loop filter is either the reconstructed samples before the DBF or the residual samples.

8. The method according to any one of claims 1-7, wherein, The edge information includes encoding / decoding information, prediction mode, boundary strength, or quantization parameters (QP).

9. The method according to any one of claims 1-8, wherein, Unavailable samples of the edge information are filled, and the filling includes mirror filling or symmetric filling.

10. The method according to any one of claims 1-9, wherein, The number of rows (N1) used in the row cache of the edge information is different from the second number (N2) used in the row cache of the reconstructed samples, where N1 <N2。 11. The method according to any one of claims 1-10, wherein, The edge information is obtained from one or more color components, which include luminance (Y), blue chromatic aberration (Cb), or red chromatic aberration (Cr) in the YCbCr color space.

12. The method according to any one of claims 1-11, wherein, The luminance loop filter boundary is derived and used for luminance-related edge information in DBF, BIF, SAO, CCSAO, ALF, or CCALF.

13. The method according to any one of claims 1-12, wherein, The chromaticity loop filter boundary is derived and used for chromaticity-related edge information in DBF, BIF, SAO, CCSAO, ALF, or CCALF.

14. The method according to any one of claims 1-13, wherein, The derivation of the luminance loop filter boundary position depends on the virtual boundary offset (vbOffset) variable, which specifies the offset of the loop filter virtual boundary or the distance between the loop filter virtual boundary and the bottom boundary of the current codec tree block (CTB). The derivation of the luminance loop filter boundary position depends on the variable M, which specifies the offset relative to the top boundary of the current CTB. The luminance position of the current edge information sample relative to the upper left sample of the current luminance CTB is represented as (x, y), the luminance position of the upper left sample of the current luminance CTB relative to the upper left sample of the current image is (xCtb, yCtb), and the size of the current luminance CTB is represented as CTB size Y (CtbSizeY).

15. The method according to any one of claims 1-14, wherein, The chroma loop filter boundary used in the 4:2:0 format is derived in the same way as the luminance loop filter boundary.

16. The method according to any one of claims 1-15, wherein, When encountering a brightness boundary location, brightness-related edge information samples are filled in.

17. The method according to any one of claims 1-16, wherein, When encountering a chromaticity boundary location, chromaticity-related edge information samples are filled in.

18. The method according to any one of claims 1-17, wherein, The use of the edge information in the loop filter is determined based on whether the sample points associated with the edge information are at the boundary.

19. The method according to any one of claims 1-18, wherein, The boundary is a codec tree unit (CTU) boundary, a CTU row boundary, or a virtual boundary.

20. The method according to any one of claims 1-19, wherein, Samples at the boundary are referred to as samples at the line cache.

21. The method according to any one of claims 1-20, wherein, The row cache limit for the edge information is applied to different stages in one or more loop filters.

22. The method according to any one of claims 1-21, wherein, The row caching restriction on the edge information is applied to both the filtering and classification stages.

23. The method according to any one of claims 1-22, wherein, The edge information includes predicted samples, residual samples, reconstructed samples before a specific loop filter, reconstructed samples after a specific loop filter, or intermediate values ​​within a specific loop filter.

24. The method according to any one of claims 1-23, wherein, The inputs used to generate intermediate values ​​include reconstructed or predicted samples prior to ALF.

25. The method according to any one of claims 1-24, wherein, The padding of unavailable samples of the edge information at the row cache is the same as the padding of unavailable samples of the reconstructed samples, or the padding is repeated padding or one-sided padding.

26. The method according to any one of claims 1-25, wherein, The use of the side information differs from the use of reconstructed samples at the line buffer of one or more loop filters, or the number of lines (N1) used in the line buffer of the side information differs from the second number (N2) used in the line buffer of the reconstructed samples, where N1>N2 or N1=0, or the side information is not stored in the line buffer, or the filling process for unavailable samples of the side information at the line buffer differs from the filling process for unavailable samples of the reconstructed samples.

27. The method according to any one of claims 1-26, wherein, The edge information comes from one or more color components, and the color components include green (G), blue (B), or red (R) in the GBR color space, or any other color space used in video encoding and decoding.

28. The method according to any one of claims 1-27, wherein, ALF chroma and CCALF are executed in parallel, or a first offset (O1) is generated from ALF chroma and a second offset (O2) is generated from CCALF. O1 and O2 are first added to the chroma sample and a clipping operation is performed according to R' = clip(R + O1 + O2), where R represents the current chroma sample, R' represents the sample filtered by ALF chroma and CCALF, and clip() represents the clipping operation, or the clipping operation is performed once on ALF chroma and CCALF.

29. The method according to any one of claims 1-28, wherein, The edge information is used for post-processing or pre-processing.

30. The method according to any one of claims 1-29, wherein, The boundary of the luminance loop filter is derived based on the luminance-related edge information, and the boundary of the chrominance loop filter is derived based on the chrominance-related edge information, wherein the boundary of the luminance loop filter is different from the boundary of the chrominance loop filter.

31. The method according to any one of claims 1-30, wherein, The chroma loop filter boundary depends on the color format or filtering process, or for 4:2:0, 4:2:2 and 4:4:4 color formats, the chroma loop filter boundary is derived in different ways, or the luminance loop filter boundary position is the top boundary position, bottom boundary position, left boundary position or right boundary position.

32. The method according to any one of claims 1-31, wherein, When y - (CtbSizeY - vbOffset) is greater than or equal to 0, the top boundary position is set to equal to yCtb + CtbSizeY - vbOffset; or when the top boundary of the current CTB is the top boundary of a slice, strip, or sub-image, or the loop filter across slices, strips, or sub-images is disabled, and when y is less than M, the top boundary position is set to equal to yCtb; or when CtbSizeY - vbOffset - y is greater than 0 and less than N, the bottom boundary position is set to equal to yCtb + CtbSizeY - vbOffset; or when the bottom boundary of the current CTB is the bottom boundary of a slice, strip, or sub-image, and the loop filter across slices, strips, or sub-images is disabled, and when CtbSizeY - y is less than L, the bottom boundary position is set to equal to yCtb + CtbSizeY.

33. The method according to any one of claims 1-32, wherein, When the chroma format is 4:2:0, during the derivation at the top or bottom boundary position, the same value of vbOffset is used for the luminance and chroma-related edge information, or vbOffset is an integer including 4, or when the chroma format is 4:2:0, during the derivation at the top or bottom boundary position, the same values ​​of M, N, and L are used for the luminance and chroma-related edge information, or M, N, and L are integers including M = 3, N = 5, and L = 5.

34. The method according to any one of claims 1-33, wherein, In 4:2:2 or 4:4:4 chroma formats, the chroma loop filter boundaries and the luminance loop filter boundaries are derived differently. Alternatively, when the chroma format is 4:2:2 or 4:4:4, during the derivation at the top or bottom boundary position, different values ​​of vbOffset are used for luminance and chroma-related edge information; either vbOffset1 is used for chroma-related edge information and vbOffset2 is used for luminance-related edge information, where vbOffset1 is not equal to vbOffset2, or vbOffset1 = 2 and vbOffset2 = 2.

4. Alternatively, when the chroma format is 4:2:2 or 4:4:4, during the derivation at the top or bottom boundary position, different values ​​of vbOffset are used for chroma-related edge information in a chroma format of 4:2:0; or when the chroma format is 4:2:2 or 4:4:4, during the derivation at the top or bottom boundary position, different values ​​of M, N, and L are used for luminance and chroma-related edge information; or M1, N1, and L1 are used for chroma-related edge information, and M2, N2, and L2 are used for luminance-related edge information, where M1 is not equal to M2, N1 is not equal to N2, and L1 is not equal to L2; or M1 = 2, M1 = 3, L1 = 3, and M2 = 3, N2 = 5, L2 = 5.

35. The method according to any one of claims 1-34, wherein, The edge information samples are filled at the boundary location, or the edge information samples are filled at different stages of the loop filter, or the stage is the classification of the offline trained filter, the classification of the online trained filter, the filtering of the offline trained filter, or the filtering of the online trained filter.

36. The method according to any one of claims 1-35, wherein, The loop filter is applied to a video unit, and the video unit is a color component, sub-picture, strip, slice, CTU, CTU line, CTU group, CU, prediction unit (PU), transform unit (TU), codec tree block (CTB), codec block (CB), prediction block (PB), transform block (TB), block, sub-block of block, sub-region within block, or any other region containing more than one sample or pixel.

37. The method according to any one of claims 1-36, wherein, The use of the side information is transmitted via signals at the sequence level, picture group level, picture level, strip level, or slice group level, and is included in the sequence header, picture header, sequence parameter set (SPS), video parameter set (VPS), decoding parameter set (DPS), decoding capability information (DCI), picture parameter set (PPS), adaptive parameter set (APS), strip header, or slice group header.

38. The method according to any one of claims 1-37, wherein, The application of the loop filter depends on: the messages transmitted via signals in the DPS, SPS, VPS, PPS, APS, picture header, strip header, slice header, codec tree unit (CTU), codec unit (CU), CTU row, CTU group, TU, PU block, or video codec unit; the position of the CU, PU, ​​TU, block, or video codec unit; the block dimension of the current block or neighboring blocks; the block shape of the current block and neighboring blocks; the codec mode of the block, including IBC, non-IBC inter-frame mode, or non-IBC sub-block mode; an indication of the color format, including 4:2:0 or 4:4:4; the codec tree structure; the strip group type, slice group type, or picture type; the color component applied only to the chroma component or the luminance component; the temporal layer ID; or the standard grade, level, or layer.

39. The method according to any one of claims 1-38, wherein, The conversion includes encoding the visual media data into the bitstream.

40. The method according to any one of claims 1-38, wherein, The conversion includes decoding the visual media data from the bitstream.

41. An apparatus for processing video data, comprising a processor and a non-transitory memory having instructions thereon, wherein, When executed by the processor, the instructions cause the processor to perform the method according to any one of claims 1-40.

42. A non-transitory computer-readable medium comprising a computer program product for use with a video encoding / decoding device, wherein, The computer program product includes computer-executable instructions stored on the non-transitory computer-readable medium, such that when the computer-executable instructions are executed by a processor, the video codec device performs the method according to any one of claims 1-40.

43. A non-transitory computer-readable recording medium storing a bitstream of video generated by a method performed by a video processing apparatus, wherein, The method includes: The use of the edge information in the loop filter is determined by applying a line cache constraint to the edge information; and The bit stream is generated based on the determination.

44. A method for storing a video bitstream, comprising: The use of the edge information in the loop filter is determined by applying a row cache constraint to the edge information; The bit stream is generated based on the determination; as well as The bit stream is stored in a non-transitory computer-readable recording medium.

Images