Video encoding method, video encoding apparatus, bitstream storage method, video decoding method, video decoding apparatus, and storage medium

Abstract

To provide a video coding method.SOLUTION: When a determination is made that multiple sub partitions satisfy a first condition of an intra prediction, the intra prediction is executed for the multiple sub partitions of a coded block in an intra sub partition (ISP) mode. Executing the intra prediction for the multiple sub partitions of the coded block includes merging at least two sub partitions of the multiple sub partitions into one prediction region of the intra prediction, and generating prediction samples in that one prediction region of the intra prediction on the basis of multiple reference samples of the coded block adjacent to that one prediction region. The first condition includes that the multiple sub-partitions comprise multiple vertical sub-partitions and each of the sub partitions has a width less than or equal to 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure generally relates to video coding and compression. More specifically, this disclosure relates to a system and method for performing video coding using an intra-sub-segment coding mode. More specifically, it relates to a video decoding method, a video decoding apparatus and a storage medium. [Background technology]

[0002] This section provides background information relating to this disclosure. The information contained in this section should not necessarily be construed as prior art.

[0003] To compress video data, one of several video encoding techniques can be used. Video encoding can be performed according to one or more video encoding standards. Some exemplary video encoding standards include VVC (versatile video coding), JEM (joint exploration test model) encoding, H.265 / HEVC (high-efficiency video coding), H.264 / AVC (advanced video coding), and MPEG (moving picture experts group) encoding.

[0004] Video coding generally utilizes prediction methods (e.g., interpretation, intrapretation) that take advantage of the inherent redundancy in video images or sequences. One goal of video coding techniques is to compress video data into a format that uses a lower bitrate while avoiding or minimizing degradation of video quality.

[0005] The initial version of the HEVC standard, completed in October 2013, offers approximately 50% bitrate savings or equivalent perceived quality compared to the previous generation video encoding standard (H.264 / MPEG AVC). While the HEVC standard offers significant encoding improvements compared to previous technologies, there is evidence that even better encoding efficiency can be achieved by using additional encoding tools. Based on this evidence, both the Video Coding Expert Group (VCEG) and the Video Expert Group (MPEG) initiated exploratory research to develop new encoding techniques for future video encoding standardization. The Joint Video Exploration Team (JVET) was established in October 2015 by ITU-T VECG and ISO / IEC MPEG to begin important research into advanced technologies that will enable significant improvements in encoding efficiency. One reference software model called the Joint Exploration Model (JEM) was maintained by JVET by integrating several additional coding tools on top of the HEVC Test Model (HM).

[0006] In October 2017, the ITU-T and ISO / IEC published a joint proposal (CfP) for video compression with capabilities exceeding HEVC. In April 2018, 23 CfP responses were received and evaluated at the 10th JVET (Japan Video Encoding Test) meeting. These responses showed a compression efficiency gain of approximately 40% compared to the HEVC standard. Based on these evaluation results, JVET launched a new project toward the development of the next-generation video coding standard, "VVC (Versatile Video Coding)." Also in April 2018, a reference software codebase called the VVC Test Model (VTM) was established to demonstrate a reference implementation of the VVC standard.

[0007] This section provides a general overview of this disclosure and is not a comprehensive disclosure of its entire scope or features. [Overview of the Initiative] [Means for solving the problem]

[0008] According to a first aspect of the present disclosure, a video encoding method is performed in a computing device having one or more processors and memory storing a plurality of programs executed by the one or more processors. The method includes independently generating an intra-prediction for each of a plurality of corresponding sub-partitions, each intra-prediction being generated using a plurality of reference samples from the current encoding block.

[0009] According to a second aspect of the present disclosure, a video coding method is performed in a computing device having one or more processors and memory storing a plurality of programs executed by the one or more processors. The method includes generating an intra-prediction for each of a plurality of corresponding subdivisions using only N modes out of M possible intra-prediction modes for the luminance component of an intra-subdivision (ISP) coding block, where M and N are positive integers and N is less than M.

[0010] According to a third aspect of the present disclosure, a video coding method is performed in a computing device having one or more processors and memory storing a plurality of programs executed by the one or more processors. The method includes generating an intra-prediction for the saturation component of an intra-sub-partitioning (ISP) coding block using only N of the possible intra-prediction modes of M, where M and N are positive integers and N is less than M.

[0011] According to a fourth aspect of the present disclosure, a video encoding method is executed in a computing device having one or more processors and a memory storing a plurality of programs executed by the one or more processors. The method generates respective intra predictions for each of a plurality of corresponding sub-divisions of an entire intra-subdivision (ISP) encoding block for a luminance component and for a chrominance component, and generates a chrominance intra prediction for the entire intra-subdivision (ISP) encoding block.

[0012] According to a fifth aspect of the present disclosure, a video encoding method is executed in a computing device having one or more processors and a memory storing a plurality of programs executed by the one or more processors. The method generates a first prediction using an intra-subdivision mode, generates a second prediction using an inter prediction mode, and combines the first prediction and the second prediction to generate a final prediction by applying a weighted average to the first prediction and the second prediction.

Brief Description of the Drawings

[0013] [Figure 1] It is a block diagram showing an exemplary encoder that can be used in conjunction with many video encoding standards. [Figure 2] It is a block diagram showing an exemplary decoder that can be used in conjunction with many video encoding standards. [Figure 3] Shows five types of exemplary block partitions for a multi-type tree structure. [Figure 4] Shows an exemplary set of intra modes for use with the VVC standard. [Figure 5] It is a diagram showing a set of a plurality of reference lines for performing intra prediction. [Figure 6A] Shows a first set of reference samples and an angular direction used to perform intra prediction of a first rectangular block. [Figure 6B]Shows a second set of reference samples and angular directions used to perform intra prediction of the second rectangular block. [Figure 6C] Shows a third set of reference samples and angular directions used to perform intra prediction of the square block. [Figure 7] Shows an exemplary set of positions for adjacent reconstructed samples used for position-dependent intra prediction combination (PDPC) of one coded block. [Figure 8A] Shows an exemplary set of short-distance intra prediction splitting (SDIP) for an 8×4 block. [Figure 8B] Shows an exemplary set of short-distance intra prediction splitting (SDIP) for a 4×8 block. [Figure 8C] Shows an exemplary set of short-distance intra prediction splitting (SDIP) for blocks of any size. [Figure 9A] A plot of chroma values as a function of luminance values, where the plot is used to derive a set of linear model parameters. [Figure 9B] Shows the positions of samples used for deriving the linear model parameters of FIG. 9A. [Figure 10] Shows the generation of reference samples for intra prediction for all sub-divisions using only reference samples outside the current coded block. [Figure 11] Shows the combination of an inter predictor sample and an intra predictor sample for the first sub-division of FIG. 10. [Figure 12] Shows the combination of an inter predictor sample and an intra prediction sample for the second sub-division of FIG. 10.

Best Mode for Carrying Out the Invention

[0014] A set of exemplary and non-limiting embodiments of this disclosure are described below in conjunction with the accompanying drawings. Variations of structures, methods, or functions may be implemented by those skilled in the art based on the examples presented herein, and all such variations are included within the scope of this disclosure. Teachings of different embodiments can be combined with one another, but are not necessarily required, where there is no conflict.

[0015] The terms used in this disclosure are intended to illustrate specific examples, not to limit this disclosure. The singular form “one,” etc., as used in this disclosure and the attached claims, also refers to the plural form unless the context clearly indicates otherwise. The terms “and / or” as used herein should be understood to refer to any or all possible combinations of one or more related enumerated items.

[0016] Here, various types of information can be described using terms such as “first,” “second,” and “third,” but these terms should not limit the information. These terms are used solely to distinguish one category of information from another. For example, without departing from the scope of this disclosure, first information may be referred to as second information, and similarly, second information may be referred to as first information. As used herein, the term “if” means “when,” “at the time,” or “in response,” depending on the context.

[0017] Throughout this specification, any single or multiple references to “one embodiment,” “a certain embodiment,” “another embodiment,” etc., mean that one or more specific features, structures, or characteristics described in relation to one embodiment are included in at least one embodiment of this disclosure. Therefore, the various occurrences of phrases such as “one embodiment,” “a certain embodiment,” “another embodiment,” etc., throughout this specification do not necessarily all refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable manner.

[0018] Conceptually, many video coding standards are similar, as described above. For example, virtually all video coding standards use block-based processing and share similar video coding block diagrams to achieve video compression. Like HEVC, the VVC standard is built on a block-based hybrid video coding framework.

[0019] Figure 1 shows a block diagram of an exemplary encoder 100, which can be used in conjunction with many video encoding standards. In encoder 100, a video frame is divided into multiple video blocks for processing. For each given video block, a prediction is formed based on either an inter-prediction approach or an intra-prediction approach. In inter-prediction, one or more predictors are formed by motion estimation and motion compensation based on pixels from previously reconstructed frames. In intra-prediction, predictors are formed based on reconstructed pixels in the current frame. Mode determination allows for the selection of the best predictor to predict the current block.

[0020] The prediction residual, representing the difference between the current video block and its predictor, is transmitted to the conversion circuit 102. The conversion coefficients are then transmitted from the conversion circuit 102 to the quantum circuit 104 for entropy reduction. The quantization coefficients are then supplied to the entropy coding circuit 106 to generate a compressed video bitstream. As shown in Figure 1, prediction-related information 110 from the inter-prediction circuit and / or intra-prediction circuit 112, such as video block division information, motion vectors, reference picture index, and intra-prediction mode, is also supplied through the entropy coding circuit 106 and stored in the compressed video bitstream 114.

[0021] Encoder 100 also requires decoder-related circuitry to reconstruct pixels for prediction purposes. First, the prediction residuals are reconstructed through the inverse quantization circuit 116 and the inverse transform circuit 118. These reconstructed prediction residuals are combined with the block predictor 120 to generate unfiltered reconstructed pixels for the current video block.

[0022] In-loop filters 115 are commonly used to improve encoding efficiency and visual quality. For example, deblocking filters are available in current versions of AVC, HEVC, and VVC. HEVC defines an additional in-loop filter called SAO (Sample Adaptive Offset) to further improve encoding efficiency. In the current VVC standard, yet another in-loop filter called ALF (Adaptive Loop Filter) is being actively considered and is likely to be included in the final standard.

[0023] These in-loop filter operations are optional. Performing these operations helps improve encoding efficiency and visual quality. They can also be turned off as determined by encoder 100 to save computational complexity.

[0024] Note that intra-prediction is typically based on unfiltered reconstructed pixels, while inter-prediction is based on filtered reconstructed pixels when these filtering options are enabled by encoder 100.

[0025] Figure 2 is a block diagram of an exemplary decoder 200 that can be used with many video encoding standards. This decoder 200 is similar to the reconstruction-related portion present in encoder 100 in Figure 1. In decoder 200 (Figure 2), the input video bitstream 201 is first decoded through an entropy decoding circuit 202 to derive quantization coefficient levels and prediction-related information. The quantized coefficient levels are processed through an inverse quantization circuit 204 and an inverse transform circuit 206 to obtain reconstructed prediction residuals. The block prediction mechanism implemented in the intra / intermode selector 212 is configured to execute either an intra-prediction procedure 208 or a motion compensation procedure 210 based on the decoded prediction information. An adder 214 is used to sum the reconstructed prediction residuals from the inverse transform circuit 206 with the prediction output generated by the block predictor mechanism to obtain a set of unfiltered reconstructed pixels. The reconstructed blocks can further pass through an in-loop filter 209 before being stored in a picture buffer 213, which functions as a reference picture store. The reconstructed video in the picture buffer 213 can then be sent out to drive the display device and can also be used to predict future video blocks. In situations where the in-loop filter 209 is turned on, filtering operations are performed on these reconstructed pixels to derive the final reconstructed video output 222.

[0026] Returning to Figure 1, the input video signal to encoder 100 is processed block by block. Each block is called an Encoded Unit (CU). In VTM-1.0, a CU may be up to 128 x 128 pixels. In HEVC (High Efficiency Video Encoding), JEM (Joint Exploration Test Model), and VVC (Versatile Video Encoding), the basic unit of compression is called an Encoded Tree Unit (CTU). However, in contrast to the HEVC standard, which divides blocks based solely on quadtrees, in the VVC standard, a single CTU is divided into CUs to adapt to local characteristics that vary based on quadtree / binary / ternary tree structures. Furthermore, the concept of multiple-partitioned unit types in the HEVC standard does not exist in the VVC standard. That is, the separation of CU, PU (Prediction Unit), and TU (Transform Unit) does not exist in the VVC standard. Instead, each CU is always used as the basic unit for both prediction and transformation without further division. The maximum CTU size for HEVC and JEM is defined as two blocks of 64x64 luminance pixels and, in the case of a 4:2:0 saturation format, two blocks of 32x32 saturation pixels. The maximum allowable size of a luminance block within a CTU is specified as 128x128 (although the maximum size of a luminance conversion block is 64x64).

[0027] Figure 3 shows five exemplary block partitions for a multi-type tree structure. The five exemplary block partitions include quad partitioning 301, horizontal duplicating partitioning 302, vertical duplicating partitioning 303, horizontal ternary partitioning 304, and vertical ternary partitioning 305. In situations where a multi-type tree structure is used, one CTU is initially partitioned by a quad tree structure. Then, each quad tree leaf node can be further partitioned by binary and ternary tree structures.

[0028] Using one or more of the exemplary block divisions 301, 302, 303, 304, or 305 in Figure 3, spatial and / or temporal predictions can be performed using the configuration shown in Figure 1. Spatial prediction (or "intra prediction") uses pixels from samples of already encoded adjacent blocks (called reference samples) within the same video picture / slice to predict the current video block. Spatial prediction reduces the spatial redundancy inherent in video signals.

[0029] Time prediction (also known as "interpretation" or "motion-compensated prediction") predicts the current video block using reconstructed pixels from an already encoded video picture. Time prediction reduces the temporal redundancy inherent in video signals. A time prediction signal for a given CU is typically signaled by one or more motion vectors (MVs) indicating the amount and direction of motion between the current CU and its time reference. If multiple reference pictures are supported, an additional reference picture index is also transmitted, which is used to identify which reference picture in the reference picture store the time prediction signal is coming from.

[0030] After spatial and / or temporal predictions are performed, an intra-mode / inter-mode determination circuit 121 within encoder 100 selects the best prediction mode, for example, based on a rate-distortion optimization method. The block predictor 120 is then subtracted from the current video block, and the resulting prediction residual is decorrelated using a transform circuit 102 and a quantization circuit 104. The obtained quantized residual coefficients are dequantized by an inverse quantization circuit 116 and inversely transformed by an inverse transform circuit 118 to form a reconstructed residual, which is then returned to the prediction block to form a reconstructed signal for the CU. Further in-loop filters 115, such as a deblocking filter, sample-adaptive offset (SAO), and / or adaptive in-loop filter (ALF), can be applied to the reconstructed CU before it is placed in the reference picture store of picture buffer 117 and used to encode future video blocks. To form the output video bitstream 114, the encoding mode (inter or intra), prediction mode information, motion information, and quantized residual coefficients are all sent to the entropy encoding unit 106, where they are further compressed and packed to form the bitstream.

[0031] The basic intra-prediction scheme applied in the VVC standard remains largely the same as that in the HEVC standard, except that several modules are further extended and / or improved in the VVC standard, such as intra-subdivision (ISP) coding mode, extended intra-wide-angle intra-prediction, position-dependent intra-prediction combination (PDPC), and 4-tap intra-interpolation. One broad aspect of this disclosure focuses on improving existing ISP designs in the VVC standard. Furthermore, other coding tools included in the VVC standard and closely related to the techniques proposed in this disclosure (e.g., tools in the intra-prediction and transform coding processes) are described in more detail below.

[0032] [Intra-predictive mode with wide-angle intra-direction] As with the HEVC standard, the VVC standard uses a set of previously decoded samples adjacent to (i.e., above or to the left of) a current CU to predict the sample for the CU. However, to capture the finer edge orientations present in natural video (especially for video content with high resolution, e.g., 4K), the number of intra-angle modes is expanded from 33 modes in the HEVC standard to 93 modes in the VVC standard. In addition to angular orientation, both the HEVC and VVC standards provide for planar modes (assuming a gently changing surface with horizontal and vertical inclinations derived from the boundary) and DC modes (assuming a flat surface).

[0033] Figure 4 illustrates an exemplary set of intra-modes 400 for use with the VVC standard, and Figure 5 illustrates a set of multiple reference lines for performing intra-prediction. Referring to Figure 4, the exemplary set of intra-modes 400 includes modes 0, 1, -14, -12, -10, -8, -6, -4, -2, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, and 80. Mode 0 corresponds to the planar mode, and Mode 1 corresponds to the DC mode. Similar to the intra-prediction process in the HEVC standard, all defined intra-modes in the VVC standard (i.e., planar, DC, and angular) utilize a set of adjacent reconstructed samples above and to the left of the predicted block as a reference for intra-prediction. However, unlike the HEVC standard, where only the nearest row / column of the reconstructed samples (rows 0, 501 in Figure 5) is used as a reference, VVC introduces multi-reference lines (MRLs) where two additional rows / columns (i.e., rows 1, 503 and rows 3, 505 in Figure 5) are used for the intra-prediction process. The index of the selected reference row / column is signaled from encoder 100 (Figure 1) to decoder 200 (Figure 2). If a row / column that is not the closest in Figure 5, such as row 1, 503 or row 3, 505, is selected, the planar and DC modes in Figure 4 are excluded from the set of intra-modes that can be used to predict the current block.

[0034] Figure 6A illustrates the first set of reference samples and angular directions 602, 604 used for intra-prediction of a rectangular block (where width W divided by height H is equal to 2). The first set of reference samples includes the first sample 601 and the second sample 603. Figure 6B shows the second set of reference samples and angular directions 606, 608 used for intra-prediction of a vertically elongated rectangular block (W / H=1 / 2). The second set of reference samples includes the third sample 605 and the fourth sample 607. Figure 6C shows the third set of reference samples and angular directions 610 and 612 used for intra-prediction of a square block (W=H). The third set of reference samples includes the fifth sample 609 and the sixth sample 610. Assuming nearest neighbor is used, Figure 6C shows the location of the third reference sample that can be used in the VVC standard to derive prediction samples for one intra-block. As shown in Figure 6C, since a quadtree / binary / ternary tree partitioning structure is applied, in addition to square coding blocks, rectangular coding blocks also exist in the intra-prediction procedure in the context of the VVC standard.

[0035] Due to the uneven width and height of a given block, a variety of sets of angular directions are selected for different block shapes, also known as wide-angle intra-prediction. In detail, in addition to planar and DC modes, 65 of the 93 angular directions are also supported for each block shape for both square and rectangular coding blocks, as shown in Table 1. Such a design not only efficiently captures the directional structures typically present in video (by adaptively selecting angular directions based on block shape), but also ensures that a total of 67 intra-modes (i.e., planar, DC, and 65 angular directions) are enabled for each coding block. This allows for good efficiency of signal intra-modes while providing a consistent design across different block sizes.

[0036] [Table 1] [Table 1: Angular Directions Selected for Intra Prediction of Different Block Shapes of VVC]

[0037] [Location-dependent intra-predictive coupling] As previously mentioned, intra-prediction samples are generated from either an unfiltered or filtered set of neighboring reference samples, which can introduce discontinuities along the block boundary between the current encoded block and its neighbors. To address this issue, boundary filtering is applied in the HEVC standard by utilizing a two-tap filter (for DC mode) or a gradient-based smoothing filter (for horizontal and vertical prediction modes) by combining the first row / column of prediction samples for DC, horizontal (i.e., mode 18 in Figure 4), and vertical (i.e., mode 50) prediction modes with an unfiltered reference sample.

[0038] The position-dependent intra-predictive coupling (PDPC) tool in the VVC standard extends the aforementioned concept by using a weighted coupling of intra-predicted samples and unfiltered reference samples. In the current VVC working draft, PDPC is enabled for the following unsignalized intra-modes: planar, DC, horizontal (i.e., mode 18), vertical (i.e., mode 50), angular directions near the lower left diagonal (i.e., modes 2, 3, 4, ..., 10), and angular directions near the upper right diagonal (i.e., modes 58, 59, 60, ..., 66). Assuming that the predicted sample located at coordinate (x,y) is pred(x,y), its corresponding value after PDPC is calculated as follows: pred(x,y)=(wL×R -1,y +wT×R x-1 -wTL×R -1,-1 +(64-wL-wT+wTL)×pred(x,y)+32)>>6 … (1) Here, R x-1, R -1,y represents the reference samples above and to the left of the current sample (x, y), respectively, and R -1,-1 represents the reference sample at the upper left corner of the current block.

[0039] Figure 7 shows an exemplary set of positions for adjacent reconstructed samples used for position-dependent intra prediction combining (PDPC) of one coded block. The first reference sample 701 (R x-1 ) represents the reference sample located above the current prediction sample (x, y). The second reference sample 703 (R -1,y ) represents the reference sample located to the left of the current prediction sample (x, y). The third reference sample 705 (R -1,-1 ) represents the reference sample located at the upper left corner of the current prediction sample (x, y).

[0040] The reference samples including the first, second, and third reference samples 701, 703, and 705 are combined with the current prediction sample (x, y) during the PDPC process. Assuming that the current coded block has a size of W×H, as follows, the weights wL, wT, and wTL in Equation (1) are adaptively selected according to the prediction mode and sample position.

[0041] In DC mode, wT = 32 >> ((y << 1) >> shift), wL = 32 >> ((x << 1) >> shift), wTL = (wL >> 4) + (wT >> 4) … (2)

[0042] In planar mode, wT = 32 >> (y << 1) >> shift), wL = 32 >> ((x << 1) >> shift), wTL = 0 … (3)

[0043] In horizontal mode, wT = 32 >> ((y << 1) >> shift), wL = 32 >> ((x << 1) >> shift), wTL = wT … (4)

[0044] In vertical mode, wT=32>>((y<<1)>>shift), wL=32>>((x<<1)>>shift), wTL=wL…(5)

[0045] In the diagonal direction to the lower left, wT=16>>((y<<1)>>shift), wL=16>>((x<<1)>>shift), wTL=0…(6)

[0046] In the upper right diagonal direction, wT=16>>((y<<1)>>shift), wL=16>>((x<<1)>>shift), wTL=0…(7)

[0047] Here, shift=(log2(W)-2+log2(H)-2+2)>>2

[0048] [Multiple transformation selection and shape-adaptive transformation selection]

[0049] The VVC standard enables the use of multiple transformation selection (MTS) tools by introducing additional core transformations, DCT-VIII and DST-VII, in addition to the DCT-II transformation used in the HEVC standard. In the VVC standard, adaptive transformation selection is enabled at the coding block level by signaling a single MTS flag to the bitstream. Specifically, if the MTS flag is equal to 0 for a block, a pair of fixed transformations (e.g., DCT-II) are applied horizontally and vertically. Otherwise (if the MTS flag is equal to 1), two additional flags are further signaled for the block to indicate the type of transformation in each direction (either DCT-VIII or DST-VII).

[0050] On the other hand, the introduction of quadtree / binary / ternary-based block partitioning structures in the VVC standard strongly correlates the distribution of intra-prediction residuals with the block shape. Therefore, when MTS is disabled (i.e., the MTS flag is equal to 0 for a single coded block), one shape-adaptive transform selection method is applied to all intra-coded blocks where the DCT-II and DST-VII transforms are implicitly enabled based on the width and height of the current block. More specifically, for each rectangular block, this method uses the DST-VII transform in the direction related to the shorter side of the block and the DCT-II transform in the direction related to the longer side of the block. For each square block, DST-VII is applied in both directions. Furthermore, to avoid introducing new transforms for different block sizes, the DST-VII transform is only enabled if the shorter side of a single intra-coded block is 16 or less. Otherwise, the DCT-II transform is always applied.

[0051] Table 2 shows the enabled horizontal and vertical transforms for intra-encoded blocks based on the shape-adaptive transform selection method in VVC.

[0052] [Table 2] [Table 2: Shape-Adaptive Transformation Selection within VVC Blocks]

[0053] [Intra-sub-partition coding mode] Conventional intra-mode coding uses only reconstructed samples adjacent to a single coded block to generate intra-predictive samples for that block. The spatial correlation between predictive and reference samples based on this method is approximately proportional to the distance between the predictive and reference samples. Therefore, samples in the inner portion (particularly those located in the lower right corner of the block) typically have lower predictive quality than samples closer to the block boundary. To further improve intra-predictive efficiency, short-range intra-prediction (SDIP) has been proposed and well-studied. This method divides a single intra-coded block into multiple sub-blocks for prediction, either horizontally or vertically. Typically, a square block is divided into four sub-blocks. For example, an 8x8 block can be divided into four 2x8 or four 8x2 sub-blocks. One extreme case of such sub-block-based intra-prediction is so-called line-based prediction, where the block is divided into one-dimensional rows / columns for prediction. For example, a single W×H (width × height) block can be divided into H subblocks of size W×1, or W subblocks of size 1×H, for intra-prediction. Each of the resulting rows / columns is encoded in the same way as a normal two-dimensional (2D) block (as shown in Figures 6A, 6B, 6C, and 7), i.e., predicted by one of the available intra-modes, and the prediction error is decorrelated based on transformation and quantization and sent to the decoder 200 (Figure 2) for reconstruction. As a result, the reconstructed sample in one subblock (e.g., row / column) can be used as a reference for predicting the sample in the next subblock. The above process is repeated until all subblocks in the current block have been predicted and encoded. Furthermore, to reduce signaling overhead, all subblocks within a single encoded block share the same intra-mode.

[0054] In SDIP, different subblock divisions can provide different coding efficiencies. Generally, line-based prediction provides the best coding efficiency because it offers the "shortest prediction distance" between different divisions. On the other hand, codec hardware implementations have the worst coding / decoding throughput. For example, consider a block with 4x4 subblocks and the same block with 4x1 or 1x4 subblocks; the latter has only a quarter of the throughput of the former. In HEVC, the minimum intra-prediction block size for luminance is 4x4.

[0055] Figure 8A shows an exemplary set of Short-Range Intra-Prediction (SDIP) partitioning for an 8x4 block 801, Figure 8B shows an exemplary set of Short-Range Intra-Prediction (SDIP) partitioning for a 4x8 block 803, and Figure 8C shows an exemplary set of Short-Range Intra-Prediction (SDIP) partitioning for a block 805 of arbitrary size. In recent years, a video coding tool called Sub-Partitioning Prediction (ISP) has been introduced into the VVC standard. Conceptually, ISP is very similar to SDIP. In detail, depending on the block size, ISP divides the current coded block into two or four sub-blocks either horizontally or vertically, with each sub-block containing at least 16 samples.

[0056] In summary, Figures 8A, 8B, and 8C illustrate all possible partitioning cases for different encoded block sizes. Furthermore, to address interactions with other encoding tools in the VVC standard, the current ISP design also includes the following main aspects:

[0057] ● Interaction with wide-angle intra-directions: ISP is combined with wide-angle intra-directions. In the current design, the block size (i.e., width / height ratio) used to determine whether the normal intra-direction or its corresponding wide-angle intra-direction should be applied is one of the original encoded blocks, i.e., the block before sub-block division.

[0058] ● Interaction with multiple reference lines: ISP cannot be enabled with multiple reference lines. In detail, in the current VVC signaling design, the ISP enable / disable flag is signaled after the MRL index. If one intrablock has one non-zero MRL index (i.e., refers to a non-nearest neighboring sample), the ISP enable / disable flag is not signaled and is inferred as 0, meaning that in this case, ISP is automatically disabled for the encoded block.

[0059] ●Interaction with the Most Probable Mode: Similar to normal intra-modes, the intra-modes used for a single ISP block are signaled via the Most Probable Mode (MPM) mechanism. However, compared to normal intra-modes, the ISP's MPM scheme has the following modifications: 1) A divided ISP block enables only the intra-modes included in the MPM list and disables all other intra-modes not included in the MPM list. 2) For a divided ISP block, its MPM list excludes DC modes, prioritizes horizontal intra-modes for ISP horizontal division and vertical modes for ISP vertical division.

[0060] ● At least one non-zero coefficient block flag (CBF): In current VVCs, a CBF flag is signaled for each transform unit (TU) to identify that a transform block contains one or more transform coefficient levels that are not equal to zero. If there is a particular block using ISP, the decoder assumes that at least one of the sub-subdivisions has a non-zero CBF. Therefore, if n is the number of sub-subdivisions and the first n-1 sub-subdivisions produced zero CBFs, then the CBF of the nth sub-subdivision is inferred to be 1. Thus, it is transmitted and does not need to be decoded.

[0061] ●Interaction with Multiple Transform Selection: ISP is applied exclusively with MTS. That is, if a coded block uses ISP, its MTS flag is not notified but is always inferred to be 0 (disabled). However, instead of always using the DCT-II transform, a fixed set of core transforms (including DST-VII and DCT-II) is implicitly applied to ISP coded blocks based on the block size. In detail, assuming that W and H are the width and height of one ISP subdivision, its horizontal and vertical transforms are selected according to the following rules, as shown in Table 3.

[0062] [Table 3] [Table 3 Selected Horizontal and Vertical Transformations for ISP Blocks]

[0063] [Prediction using a cross-component linear model] Figure 9A is a plot of saturation values ​​as a function of luminance values, where the plot is used to derive a set of linear model parameters. More specifically, the straight line 901 representing the relationship between saturation and luminance values ​​is used to derive a set of linear model parameters, as shown below. To reduce cross-component redundancy, the cross-component linear model (CCLM) prediction mode is used in the VVC, so that saturation samples are predicted based on reconfigured luminance samples of the same CU by using the following linear model. Nod C (i,j) = α·rec L '(i,j)+β …(8) Here, pred C (i,j) represents the predicted saturation sample within CU, rec L '(i,j) represents a downsampled and reconstructed luminance sample of the same CU. The linear model parameters α and β are derived from the two samples, as illustrated in Figure 9A, from the straight line 901 representing the relationship between luminance and chrominance values. These are the minimum luminance sample A(X A, Y A ) and the maximum luminance sample B(X) within the set of adjacent luminance samples. B , Y B ) is the case here, X A , Y A These are the x-coordinate (luminance value) and y-coordinate (saturation value) values ​​of sample A, X B , Y B These are the x and y coordinate values ​​for sample B. The linear model parameters are obtained according to the following equation. α=(y B -y A ) / (x B -x A ) β=y A -αx A This method is also called the min-max method. The division in the above formula can be avoided and replaced with multiplication and shift.

[0064] Figure 9B shows the sample positions used to derive the linear model parameters in Figure 9A. For coding blocks with a square shape, the two equations above apply directly to the linear model parameters α and β. For non-square coding blocks, adjacent samples on the longer boundary are first subsampled to have the same number of samples as on the shorter boundary. Figure 9B shows the left and upper sample positions involved in the CCLM mode, including N×N sets of chrominance samples 903 and 2N×2N sets of luminance samples 905, as well as the samples in the current block. In addition to using the upper and left templates to calculate the linear model coefficients together, these templates can also be used alternatively in two other LM modes called LM_A and LM_L modes.

[0065] In LM_A mode, only the pixel samples within the template above are used to calculate the linear model coefficients. To obtain more samples, the template above is extended to (W+W). In LM_L mode, only the pixel samples within the left template are used to calculate the linear model coefficients. To obtain more samples, the left template is extended to (H+H). Note that when the upper reference line is at the CTU boundary, only one luminance line (a common line buffer in intra-prediction) is used to create downsampled luminance samples.

[0066] In the case of saturation intra-mode coding, a total of eight intra-modes are permitted for saturation intra-mode coding. These modes include five conventional intra-modes and three cross-component linear model modes (CCLM, LM_A, and LM_L). The saturation mode signaling and derivation process is shown in Table 4. Saturation mode coding directly depends on the intra-prediction mode of the corresponding luminance block. In an I-slice, separate block partitioning structures are available for the luminance and saturation components, so one saturation block can correspond to multiple luminance blocks. Therefore, in the case of saturation DM mode, the intra-prediction mode of the corresponding luminance block covering the center position of the current saturation block is directly inherited.

[0067] [Table 4] [Table 4: Deriving the saturation prediction mode from the brightness mode when CCLM_ is enabled]

[0068] While ISP tools in VVC can improve intra-predictive efficiency, there is still room to further improve VVC performance. Meanwhile, some parts of existing ISPs would benefit from further simplification to provide more efficient codec hardware implementations and / or improved coding efficiency. This disclosure proposes several methods to further improve ISP coding efficiency, simplify existing ISP designs, and / or facilitate improved hardware implementations.

[0069] [Generating independent (or parallel) sub-partitioning predictors for ISPs] Figure 10 shows the generation of reference samples for intra-predictions 1007 for all sub-partitions using only reference samples from outside the current coding block 1000. The current coding block 1000 includes the first sub-partitions 1, 1001, the second sub-partitions 2, 1002, the third sub-partitions 3, 1003, and the fourth sub-partitions 4, 1004. In this disclosure, it is proposed to generate intra-predictions independently for each sub-partition 1001, 1002, 1003, and 1004. In other words, all predictors for sub-partitions 1001, 1002, 1003, and 1004 can be generated in parallel. In one embodiment, predictors for all sub-partitions are generated using the same method as used in conventional non-sub-partition intra-mode. In detail, the reconfigured samples of one sub-partition are not used to generate intra-prediction samples for any other sub-partitions within the same coding unit; all predictors for each sub-partition 1001, 1002, 1003, and 1004 are generated using the reference samples of the current coding block 1000, as shown in Figure 10.

[0070] In the ISP mode of the VVC standard, the width of each sub-division can be 2 or less. One detailed example is as follows: According to the ISP mode of the VVC standard, the 2×N (width × height) sub-block prediction is not allowed to depend on the reconstructed values ​​of previously decoded 2×N sub-blocks of the encoded block, and as a result, the minimum width for sub-block prediction is 4 samples. For example, an 8×8 encoded block encoded using ISP with vertical partitioning is divided into four prediction regions, each 2×8 in size, and the two leftmost 2×8 prediction regions are merged into a first 4×8 prediction region to perform intra-prediction. The transformation circuit 102 (Figure 1) is applied to each 2×8 division.

[0071] In this example, the two 2x8 prediction regions on the right are merged into a second 4x8 prediction region to perform intra-prediction. The transformation circuit 102 is applied to each 2x8 division. Note that the first 4x8 prediction region generates intra-predictors using adjacent pixels of the current coded block, and the second 4x8 region uses reconstructed pixels from the first 4x8 region (located to the left of the second 4x8 region) or adjacent pixels from the current coded block (located above the second 4x8).

[0072] In another embodiment, it should be noted that intra-predictions for horizontal subdivisions can be formed using only the horizontal (HOR) prediction mode (mode 18 as shown in Figure 4) and only prediction modes having a mode index smaller than 18 (as shown in Figure 4), and intra-predictions for vertical subdivisions can be formed using only the vertical (VER) prediction mode (i.e., mode 50 as shown in Figure 4) and prediction modes having a mode index larger than 50 (as shown in Figure 4). As a result, intra-predictions for each horizontal subdivision can be performed independently and in parallel with the HOR prediction mode (shown as mode 18 in Figure 4) and all angle prediction modes with a mode index smaller than 18. Similarly, intra-predictions for each vertical subdivision can be performed independently and in parallel with the VER prediction mode (mode 50 in Figure 4) and all angle prediction modes with a mode greater than 50.

[0073] [Intra-predictive mode coding for luminance components for ISPs] In this disclosure, it is proposed to allow only N modes out of all possible intra-prediction modes for the luminance component of an ISP coding block (where N is a positive integer). In one embodiment, only one mode is allowed for the luminance component of the ISP coding block. For example, this single-allowed mode may be a planar mode. In another example, this single-allowed mode may be a DC mode. In a third example, this single-allowed mode may be one of the HOR prediction mode, VER prediction mode, or diagonal (DIA) mode (mode 34 in Figure 4) intra-prediction modes.

[0074] In another embodiment, only one mode is permitted for the luminance component of an ISP coded block, and this mode may differ depending on the direction of subdivision, i.e., whether it is horizontal subdivision or vertical subdivision. For example, only the HOR prediction mode may be permitted for horizontal subdivision, while only the VER prediction mode may be permitted for vertical subdivision. In yet another example, only the VER prediction mode may be permitted for horizontal subdivision, while only the HOR prediction mode may be permitted for vertical subdivision.

[0075] In yet another embodiment, only two modes are permitted for the luminance component of an ISP coded block. Each of these modes may be selected in response to the direction of the corresponding subdivision, i.e., whether the subdivision direction is horizontal or vertical. For example, only the planar and HOR prediction modes are permitted for horizontal subdivision, while only the planar and VER prediction modes are permitted for vertical subdivision.

[0076] The conventional most likely mode (MPM) mechanism is not used to signal the N allowed modes for the luminance component of an ISP coded block. Instead, the inventors propose signaling the intra-modes for an ISP coded block using a binary code word determined for each intra-mode. The code word can be generated using any of several different processes, including truncated binary (TB) binarization, fixed-length binarization, truncated rice (TR) binarization, k-order Exp-Golomb binarization, and limited EGk binarization. These binary code word generation processes are clearly defined in the HEVC specification. Truncated rice, where the rice parameter is equal to zero, is also known as truncated unary binarization. Table 5 shows examples of sets of code words using different binarization methods.

[0077] [Table 5] [Table 5: Binary code words generated using various binarization methods]

[0078] [Generating independent (or parallel) sub-partitioning predictors for ISPs] In yet another embodiment, the MPM derivation process for normal intra-mode is directly reused for ISP mode, and the method for signaling the MPM flags and MPM indices is kept the same as in the existing ISP design.

[0079] [Intra-predictive mode coding for saturation components for ISPs] In this disclosure, the ISP coded block (N c For the saturation component (where is a positive integer), N is obtained from all possible saturation intra-prediction modes. cIt is proposed to allow only one mode. In one embodiment, only one mode is allowed for the saturation component of an ISP coding block. For example, this single-allowed mode may be the direct mode (DM). In another example, this single-allowed mode may be the LM mode. In a third example, this single-allowed mode may be either the HOR predictive mode or the VER predictive mode. The direct mode (DM) is configured to apply the same intra predictive mode used by the corresponding luminance block to the saturation block.

[0080] In another embodiment, only two modes are permitted for the saturation component of an ISP coded block. In one example, only DM and LM are permitted for the saturation component of an ISP coded block.

[0081] In yet another embodiment, only four modes are permitted for the saturation component of an ISP coded block. For example, only DM, LM, LM_L, and LM_A are permitted for the saturation component of an ISP coded block.

[0082] N for the saturation component of ISP coding blocks c Conventional MPM mechanisms are not used to signal modes. Instead, a fixed binary code word is used to indicate the saturation mode selected in the bitstream. For example, the saturation intra-prediction mode of an ISP coded block can be signaled using a determined binary code word. The code word can be generated using different processes, including truncated binary (TB) binarization, fixed-length binarization, truncated Rice (TR) binarization, k-order Exp-Golomb binarization, and limited EGk binarization.

[0083] [Encoded block size of the saturation component of the ISP encoded block] This disclosure proposes not allowing subdivision coding for the chroma component of an ISP coded block. Instead, the chroma component of an ISP coded block is treated with the usual whole-block based intra prediction. In other words, for an ISP coded block, subdivision is performed only on its luminance component, which does not have a subdivision for that chroma component.

[0084] [Combination of ISP and Internet Forecasting] Figure 11 shows the combination of inter-predictor samples and intra-predictor samples for the first sub-partition 1001 of Figure 10. Similarly, Figure 12 shows the combination of inter-predictor samples and intra-predictor samples for the second sub-partition 1002 of Figure 10. More specifically, to further improve coding efficiency, a new prediction mode is provided in which predictions are generated as a weighted combination (e.g., weighted averaging) of ISP mode and inter-prediction mode. Intra-predictor generation for ISP mode is the same as described above in relation to Figure 10. Inter-predictors may be generated by a merge mode or inter-mode process.

[0085] In the illustrative example in Figure 11, the inter-predictor sample 1101 for the current block (including all sub-partitions) is generated by performing motion compensation using merge candidates indicated by the merge index. The intra-predictor sample 1103 is generated by performing intra-prediction using signaled intra-modes. Note that this process can generate intra-predictor samples for a sub-partition other than the first (i.e., the second sub-partition 1002), as shown in Figure 12, using reconfigured samples from previous sub-partitions. After the inter and intra-predictor samples are generated, they are weighted averaged to generate the final predictor samples for the sub-partition. Combined modes can be treated as intra-modes. Alternatively, combined modes may be treated as inter-modes or merged modes instead of intra-modes.

[0086] [CBF signaling for ISP coded blocks] To simplify the design of the ISP, this disclosure proposes always signaling the CBF for the final subdivision.

[0087] In another embodiment of the present disclosure, it is proposed that the CBF of the last sub-division is not signaled, but rather its value is inferred by the decoder. For example, the value of the CBF of the last sub-division is always inferred to be 1. In another example, the value of the CBF for the last sub-division is always inferred to be zero.

[0088] According to one embodiment of the present disclosure, a video coding method includes independently generating an intra-prediction for each of a plurality of corresponding subdivisions, each intra-prediction being generated using a plurality of reference samples from the current coding block.

[0089] In some examples, the reconstructed samples from the first sub-split of several corresponding sub-splits are not used to generate their respective intra-predictions for any other sub-splits among the several corresponding sub-splits.

[0090] In some examples, each of the multiple corresponding subdivisions has a width of 2 or less.

[0091] In some examples, multiple corresponding subdivisions include multiple vertical subdivisions and multiple horizontal subdivisions, and the method further comprises generating a first set of intra-predictions for the multiple horizontal subdivisions using only the horizontal prediction mode, and generating a second set of intra-predictions for the multiple vertical subdivisions using only the vertical prediction mode.

[0092] In some examples, the horizontal forecast mode is performed using a mode index less than 18.

[0093] In some examples, the vertical prediction mode is performed using a mode index greater than 50.

[0094] In some examples, the horizontal prediction mode is executed independently and in parallel for each of the multiple horizontal subdivisions.

[0095] In some examples, the vertical prediction mode is executed independently and in parallel for each of the multiple vertical subdivisions.

[0096] In some examples, multiple corresponding subdivisions include the last subdivision, and the method further comprises signaling the coefficient block flag (CBF) value of the last subdivision.

[0097] In some examples, multiple corresponding subdivisions include the last subdivision, and this method further comprises the decoder inferring the coefficient block flag (CBF) value of the last subdivision.

[0098] In some cases, the coefficient block flag (CBF) value is always inferred to be 1.

[0099] In some examples, the coefficient block flag (CBF) value is always inferred to be zero.

[0100] According to another embodiment of the present disclosure, a video coding method comprises generating an intra-prediction for each of a plurality of corresponding subdivisions using only N modes out of M possible intra-prediction modes for the luminance component of an intra-subdivision (ISP) coding block, where M and N are positive integers and N is less than M.

[0101] In some examples, each of the multiple corresponding subdivisions has a width of 2 or less.

[0102] In some examples, N is equal to 1, and as a result, only single modes are allowed for the luminance component.

[0103] In some examples, the single mode is a planar mode.

[0104] In some cases, single mode is DC mode.

[0105] In some examples, a single mode is one of the following: horizontal (HOR) prediction mode, vertical (VER) prediction mode, or diagonal (DIA) prediction mode.

[0106] In some examples, the single mode is selected in response to the direction of subdivision, the horizontal (HOR) prediction mode is selected in response to the direction of subdivision being horizontal, and the vertical (VER) prediction mode is selected in response to the direction of subdivision being vertical.

[0107] In some examples, the single mode is selected in response to the direction of the subdivision, the horizontal (HOR) prediction mode is selected in response to the direction of the subdivision being vertical, and the vertical (VER) prediction mode is selected in response to the direction of the subdivision being horizontal.

[0108] In some examples, N is equal to 2, and two modes are allowed for the luminance component.

[0109] In some examples, the first set of two modes is selected in response to the direction of the first subdivision, and the second set of two modes is selected in response to the direction of the second subdivision.

[0110] In some examples, the first set of two modes includes a planar mode and a horizontal (HOR) prediction mode, with the first sub-division direction including horizontal sub-division; and the second set of modes includes a planar mode and a vertical (VER) prediction mode, with the second sub-division direction including vertical sub-division.

[0111] In some examples, each of the N modes is signaled using a corresponding binary code word from a given set of binary code words.

[0112] In some examples, a given set of binary code words is generated using at least one of the following processes: truncated binary (TB) binarization, fixed-length binarization, truncated rice (TR) binarization, truncated unary binarization, k-order Exp-Golumb binarization, or limited EGk binarization.

[0113] According to another embodiment of the present disclosure, a video coding method comprises generating an intra-prediction for the saturation component of an intra-subdivision (ISP) coding block using only N modes out of M possible intra-prediction modes, where M and N are positive integers and N is less than M.

[0114] In some cases, N is equal to 1, and as a result, only single mode is allowed for the saturation component.

[0115] In some examples, single-mode modes include direct mode (DM), linear model (LM) mode, horizontal (HOR) predictive mode, or vertical (VER) predictive mode.

[0116] In some examples, N is equal to 2, and as a result, two modes are allowed for the saturation component.

[0117] In some examples, N is equal to 4, and as a result, four modes are allowed for the saturation component.

[0118] In some examples, each of the N modes is signaled using a corresponding binary code word from a given set of binary code words.

[0119] In some examples, a given set of binary code words is generated using at least one of the following processes: truncated binary (TB) binarization, fixed-length binarization, truncated rice (TR) binarization, truncated unary binarization, k-order Exp-Golumb binarization, or limited EGk binarization.

[0120] According to another embodiment of the present disclosure, a video coding method comprises generating a luminance intra-prediction for each of a plurality of corresponding subdivisions of an entire intra-subdivision (ISP) coding block for the luminance component, and for the chroma component, and generating a chroma intra-prediction for the entire intra-subdivision (ISP) coding block.

[0121] In some examples, each of the multiple corresponding subdivisions has a width of 2 or less.

[0122] According to another embodiment of the present disclosure, a video coding method generates a first prediction using an intra-sub division mode, generates a second prediction using an inter-prediction mode, and combines the first and second predictions to generate a final prediction by applying a weighted average to the first and second predictions.

[0123] In some examples, the second prediction is generated using at least one of either merge mode or intermode.

[0124] In one or more examples, the described functions may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or codes on or transmitted through a computer-readable medium and executed by a hardware-based processing unit. The computer-readable medium may include computer-readable storage media corresponding to tangible media such as data storage media, or communication media including any medium that facilitates the transfer of computer programs from one location to another, for example, according to a communication protocol. Thus, the computer-readable medium can generally correspond to (1) non-transient tangible computer-readable storage media, or (2) communication media such as signals or carrier waves. The data storage medium may be any available medium accessible by one or more computers or one or more processors for retrieving instructions, codes and / or data structures for implementation described in this application. A computer program product may include computer-readable media.

[0125] Furthermore, the above methods may be implemented using a device that includes one or more circuits, including application-specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic components. The device may use the circuits in combination with other hardware or software components to perform the above methods. Each module, submodule, unit, or subunit disclosed above may be at least partially implemented using one or more circuits.

[0126] Other embodiments of the present invention will become apparent to those skilled in the art by considering this specification and by practicing the invention disclosed herein. This application is intended to encompass any modifications, uses, or adaptations of the invention, including deviations from this disclosure that fall within the scope of known or customary practices in the art, in accordance with the general principles of the invention. This specification and each embodiment are intended to be illustrative only, and the true scope and spirit of the invention are described in the claims.

[0127] It will be understood that the present invention is not strictly limited to the examples described above and shown in the accompanying drawings, and that various modifications and changes can be made without departing from the scope of the invention. The scope of the present invention is intended to be limited only by the appended claims.

[0128] [Cross-reference of related applications] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 801,214, filed on February 5, 2019. The entire disclosure of the aforementioned application is incorporated herein by reference in whole.

Claims

1. If it is determined that multiple subdivisions satisfy the first condition of intra prediction, the intra prediction is performed for the multiple subdivisions of the coded block in intra subdivision (ISP) mode. Performing the intra prediction for the plurality of subdivisions of the coding block means that At least two of the above-mentioned subdivisions are merged into one prediction region of the intra prediction. Based on a plurality of reference samples of the coding block adjacent to the one prediction region, prediction samples of the one prediction region of the intra prediction are generated. This includes, The first condition includes that the plurality of subdivisions are a plurality of vertical subdivisions, and each of the subdivisions has a width of 2 or less. Video encoding method.

2. A sample reconstructed from one of the at least two sub-sub The video encoding method according to claim 1.

3. The further includes generating a set of prediction samples for the plurality of vertical subdivisions using a vertical prediction mode with a mode index greater than 50, The video encoding method according to claim 1.

4. The further includes independently and in parallel performing the intra-prediction for each sample of the prediction region. The video encoding method according to claim 1.

5. The aforementioned sub-partitions include the last sub-partition, Further comprising signaling the coefficient block flag (CBF) value for the last subdivision, The video encoding method according to claim 1.

6. The aforementioned sub-partitions include the last sub-partition, The encoder further includes estimating the coefficient block flag (CBF) value of the last subdivision, The video encoding method according to claim 1.

7. The coefficient block flag (CBF) value is presumed to be 1 or 0. The video encoding method according to claim 6.

8. For the aforementioned subdivisions, the multiple prediction samples of the intra prediction are generated in parallel. The video encoding method according to claim 1.

9. One or more processors, A non-temporary computer-readable memory storing instructions that can be executed by the one or more processors, Includes, The one or more processors mentioned above generate a bitstream and store the bitstream, If it is determined that multiple subdivisions satisfy the first condition for intra prediction, intra prediction is performed for the multiple subdivisions of the coded block in intra subdivision (ISP) mode. It is configured in such a way, Performing the intra prediction for the plurality of subdivisions of the coding block means that At least two of the aforementioned subdivisions are merged into one prediction region of the intra prediction. Based on a plurality of reference samples of the coding block adjacent to the one prediction region, prediction samples of the one prediction region of the intra prediction are generated. This includes, The first condition includes that the plurality of subdivisions are a plurality of vertical subdivisions, and each of the subdivisions has a width of 2 or less. Video encoding device.

10. A sample reconstructed from one of the at least two sub-sub The video encoding device according to claim 9.

11. The aforementioned one or more processors further, Using a vertical prediction mode with a mode index greater than 50, generate a set of prediction samples for the multiple vertical subdivisions. It is structured in such a way. The video encoding device according to claim 9.

12. A non-temporary computer-readable storage medium storing multiple programs executed by a video encoding device having one or more processors, When executed by the one or more processors, the plurality of programs cause the video encoding device to execute the video encoding method described in any one of claims 1 to 8. Non-temporary computer-readable storage medium.

13. A method for storing a bitstream, A bitstream is generated by performing the video encoding method according to any one of claims 1 to 8. The bitstream is stored in method.

14. If it is determined that multiple subdivisions satisfy the first condition of intra prediction, the intra prediction is performed for the multiple subdivisions of the coded block in intra subdivision (ISP) mode. The encoding block is associated with a predetermined division method, The division method includes four divisions, three horizontal divisions, three vertical divisions, two horizontal divisions, or two vertical divisions. Performing the intra prediction for the plurality of subdivisions of the coding block means that At least two of the above-mentioned subdivisions are merged into one prediction region of the intra prediction. Based on a plurality of reference samples of the coding block adjacent to the one prediction region, prediction samples of the one prediction region of the intra prediction are generated. This includes, The first condition includes that the plurality of subdivisions are a plurality of vertical subdivisions, and each of the subdivisions has a width of 2 or less. Video decryption method.

15. A sample reconstructed from one of the at least two sub-sub The video decoding method according to claim 14.

16. The further includes generating a set of prediction samples for the plurality of vertical subdivisions using a vertical prediction mode having a mode index greater than 50. The video decoding method according to claim 14.

17. The further includes performing the intra-prediction independently and in parallel for each sample of the prediction region. The video decoding method according to claim 14.

18. The aforementioned plurality of sub-partitions include the last sub-partition, Further comprising signaling the coefficient block flag (CBF) value for the last subdivision, The video decoding method according to claim 14.

19. The aforementioned plurality of sub-partitions include the last sub-partition, The decoder further includes inferring the coefficient block flag (CBF) value of the last subdivision, The video decoding method according to claim 14.

20. The coefficient block flag (CBF) value is inferred to be 1 or 0. The video decoding method according to claim 19.

21. Multiple prediction samples of the intra prediction are generated in parallel for the multiple subdivisions. The video decoding method according to claim 14.

22. One or more processors, A non-temporary computer-readable memory that stores instructions executable by the one or more processors, Includes, The one or more processors mentioned above are: If it is determined that multiple subdivisions satisfy the first condition for intra prediction, intra prediction is performed for the multiple subdivisions of the coded block in intra subdivision (ISP) mode. It is configured in such a way, The encoding block is associated with a predetermined division method, The aforementioned predetermined division method includes four divisions, three horizontal divisions, three vertical divisions, two horizontal divisions, or two vertical divisions. Performing the intra prediction for the plurality of subdivisions of the coding block means that At least two of the above-mentioned subdivisions are merged into one prediction region of the intra prediction. Based on multiple reference samples of the coding block adjacent to the prediction region, a prediction sample of the one prediction region of the intra prediction is generated. This includes, The first condition includes that the plurality of subdivisions are a plurality of vertical subdivisions, and each of the subdivisions has a width of 2 or less. Video decoding device.

23. A sample reconstructed from one of the at least two sub-sub The video decoding apparatus according to claim 22.

24. The aforementioned one or more processors further, A set of prediction samples is generated for the plurality of vertical subdivisions using a vertical prediction mode having a mode index greater than 50. It is structured in such a way. The video decoding apparatus according to claim 22.

25. A non-temporary computer-readable storage medium storing multiple programs executed by a video decoding device having one or more processors, When executed by the one or more processors, the plurality of programs cause the video decoding device to execute the video decoding method described in any one of claims 14 to 21. Non-temporary computer-readable storage medium.

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