Improvements to spatial geometric segmentation modes for video coding

Abstract

Disclosed are video encoding / decoding methods and systems for improving spatial geometric partitioning modes. The video encoding / decoding method comprises encoding a candidate index code into a bitstream and decoding the candidate index code from the bitstream, the candidate index code being associated with an intra-partitioning prediction and a template, the template comprising one or more reference lines of index designation within a plurality of reference lines having a plurality of reconstructed samples, the plurality of reconstructed samples being spatially adjacent to blocks associated with a spatial geometric partitioning mode (SGPM).

Description

[Technical Field]

[0001] (Cross-reference of related applications) This application claims priority to U.S. Provisional Application No. 63 / 380,943, filed on 25 October 2022, titled "INTRA FUSION AND MULTIPLE REFERENCE LINES FOR SPATIAL GEOMETRIC PARTITIONING MODE," the entirety of which is incorporated by reference into this application.

[0002] This disclosure generally relates to computer-implemented video processing methods and systems, and more specifically to improvements in spatial geometric partitioning modes for video coding. [Background technology]

[0003] Video coding is used in a wide range of applications. For example, in spatial geometric partitioning mode (SGPM), one intra-mode is used for each partition of an SGPM block, and a fixed reference is used to generate predictions for a given mode. Therefore, further improvements in video coding performance are needed. [Overview of the initiative] [Problems that the invention aims to solve]

[0004] This disclosure aims to provide video processing methods and systems for improving video encoding performance. [Means for solving the problem]

[0005] In a first aspect of this disclosure, a video encoding method comprises encoding a candidate index code into a bitstream, wherein the candidate index code is associated with an intra-partition prediction and a template, the template comprising one or more index-specified reference lines in a plurality of reference lines having a plurality of reconstructed samples, the plurality of reconstructed samples being spatially adjacent to blocks associated with a spatial geometric partitioning mode (SGPM).

[0006] In a second embodiment of the present disclosure, the video encoding system comprises a processor and memory coupled to the processor, wherein the processor executes program instructions stored in the memory to execute one of the video encoding methods described above.

[0007] In a third aspect of this disclosure, a non-temporary computer-readable medium stores program code that is executed by a processor to cause the processor to execute one of the above video encoding methods.

[0008] In a fourth aspect of the present disclosure, a video decoding method comprises decoding a candidate index code from a bitstream, wherein the candidate index code is associated with an intra-partitioning prediction and a template, the template comprising one or more reference lines of index designation within a plurality of reference lines having a plurality of reconstructed samples, the plurality of reconstructed samples being spatially adjacent to blocks associated with a spatial geometric partitioning mode (SGPM).

[0009] In a fifth aspect of this disclosure, the video decoding system comprises a processor and memory coupled to the processor, wherein the processor executes program instructions stored in the memory to execute one of the video decoding methods described above.

[0010] In a sixth aspect of this disclosure, a non-temporary computer-readable medium stores program code that is executed by a processor to cause the processor to execute one of the video decoding methods described above. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram showing a picture divided into blocks called coding tree units (CTUs), applicable to the embodiments of this disclosure. [Figure 2] This is a schematic diagram showing a coding tree unit divided into coding units (CUs) applicable to the embodiments of this disclosure. [Figure 3] This is a schematic diagram showing examples of a current block (e.g., CU) and spatially adjacent and non-adjacent reconstructed samples applicable to the embodiments of this disclosure. [Figure 4] This is a schematic diagram showing examples of angle mode and wide-angle intra prediction (WAIP) mode applicable to the embodiments of this disclosure. [Figure 5] This is a schematic diagram illustrating an example of spatial geometric partitioning mode (SGPM) signaling applicable to the embodiments of this disclosure. [Figure 6] This is a schematic diagram showing examples of template shapes and extended weights applicable to the embodiments of this disclosure. [Figure 7] This schematic diagram shows examples of geometric partitioning modes (GPMs) with inter and intra predictions, and SGPMs with inter and intra predictions, relating to available intra prediction mode (IPM) candidates applicable to the embodiments of this disclosure. [Figure 8] This is a schematic diagram showing an example of blend weights applicable to the embodiments of this disclosure. [Figure 9]It is a flowchart showing a video encoding method according to an embodiment of the present disclosure. [Figure 10] It is a flowchart showing a video decoding method according to an embodiment of the present disclosure. [Figure 11] It is an exemplary block diagram showing an example of a computing device according to an embodiment of the present disclosure.

Modes for Carrying Out the Invention

[0012] For the purpose of more clearly explaining the embodiments of the present disclosure or related technologies, the above is a brief introduction to the drawings described in the following embodiments. Obviously, the drawings only show some embodiments of the present disclosure, and those skilled in the art can obtain other drawings based on these drawings without dealing with the prerequisite conditions.

[0013] The embodiments of the present disclosure will be described in detail below with reference to the drawings in terms of technical solutions, structural features, achieved objects, and effects. Specifically, the terms in the embodiments of the present disclosure are only used to explain specific embodiments and are not intended to limit the present disclosure.

[0014] Video encoding is used in a wide range of applications. For example, in the spatial geometry partitioning mode (SGPM), one intra mode is used for each partition of the SGPM block, and a fixed reference is used to generate a prediction of a predetermined mode. Therefore, further improvement in video encoding performance is required.

[0015] In the present disclosure, encoding and decoding refer to encoding methods and systems, and decoding methods and systems.

[0016] For example, intra-fusion and multiple reference lines can be applied to the geometric partitioning mode (GPM) of video coding in this disclosure. The methods provided in this disclosure can be used in future video coding standards. Implementations of the provided methods may consider modifying the bitstream structure, syntax, constraints, and mappings for generating decoded pictures for standardization purposes. Relevant explanations are as follows:

[0017] For example, like other video coding schemes such as High Efficiency Video Coding (HEVC), Versatile Video Coding (VVC) is a block-based hybrid spatial and temporal prediction coding scheme. In coding, as shown in Figure 1, the input picture is first divided into square blocks called coding tree units (CTUs) 100, for example, a CTU 100 can be a block of 128 × 128 pixels or a block of other pixels.

[0018] For example, as shown in Figure 2, Figure 2 is a schematic diagram showing an encoded tree unit divided into encoded units (CUs) applicable to embodiments of the present disclosure, where solid lines indicate a quadtree division and dashed lines indicate a binary tree division. In Figure 2, one CTU200 in the picture can be divided into one or more encoded units (CUs)202 used for prediction and transformation. Unlike HEVC, in VVC, the CU202 may be rectangular or square and can be encoded without further division into prediction or transformation units. In one example, each CU202 may be the same size as its root CTU200, or it may be a subdivision of its root CTU200 as small as 4x4 blocks. Furthermore, an example of prediction is shown below.

[0019] Intraprediction in VVC and ECM For example, in an intraCU, the current block is predicted using spatially adjacent reconstructed samples, and the intra mode is signaled only once for the entire CU. Intra prediction and transform coding are performed at the CU level and the transform block (TB) level, respectively. Each CU consists of a single TB, except for intra subpartition (ISP) mode and implicit partition prediction. For a luminance CU, the maximum side length of the TB is 64 and the minimum side length is 4. Furthermore, the luminance TB is specified as a W×H rectangular block with width W and height H, where W,H ∈ {4, 8, 16, 32, 64}. For a chromaticity CU, the maximum TB side length is 32, and the chromaticity TB is a W×H rectangular block with width W and height H, where W,H ∈ {2, 4, 8, 16, 32}, but 2×H and 4×2 shaped blocks are excluded to address memory architecture and throughput requirements.

[0020] For example, in a VVC, an intra-predictive sample of the current block is generated using a reference sample obtained from a reconstructed sample of an adjacent block (e.g., the block to the left and the block above the current block). As shown in Figure 3, in the case of a W×H block 300, the reference sample (e.g., the top and left reconstructed samples) is spatially adjacent to the current block (e.g., CU) 302. For example, the reference sample consists of a vertical line of 2×H reconstructed samples located to the left of the block and extending downwards, and a horizontal line of 2×W reconstructed samples located at the top of the current block and extending to the right. In this disclosure, this inverted "L" shaped sample set is also referred to as a "reference line" 302. Of the multiple reference lines 302, one reference line directly adjacent to the current block 302 is shown as the line with index 0, and of the multiple reference lines 302 that are not adjacent to the current block 302 are shown as the lines with indices 1, 2, 3, 4, 5, 6, 7...

[0021] For example, like AVC and HEVC, VVC also supports angular intra-prediction modes. Angular intra-prediction is a directional intra-prediction method. Compared to HEVC, VVC's angular intra-prediction is modified by improved prediction accuracy and adaptation to a new partitioning framework. Improved prediction accuracy is achieved by increasing the number of angular prediction directions and using more accurate interpolation filters, while adaptation to a new partitioning framework is achieved by introducing wide-angle intra-prediction modes. In VVC, the number of directional modes available in a given block increases from 33 directions in HEVC to 65 directions. Figure 4 shows a schematic diagram of Graph 400 of the different angular modes in VVC. Directions with even indices from 2 to 66 correspond to the angular mode directions supported in HEVC. For a square block, the same number of angular modes are assigned to the top and left side of the block. In another embodiment, rectangular intra-blocks, which do not exist in HEVC, are the core of the VVC partitioning scheme, having additional intra-prediction directions assigned to the longer sides of the block. The additional modes assigned along the longer sides are called Wide-Angle Intra-Prediction (WAIP) modes, because, in contrast to horizontal or vertical modes, WAIP modes correspond to prediction directions where the angle exceeds 45 degrees (°). As shown in Figure 4, a WAIP mode for a given mode index is defined by mapping the original directional mode to a mode that has the opposite direction and whose index offset is equal to 1. For a given rectangular block, the aspect ratio (i.e., the ratio of width to height) is used to determine which angular mode is replaced by the corresponding wide-angle mode.

[0022] In VVC, both square and rectangular blocks can use one non-adjacent reference line called a multiple reference line (MRL). For example, predictions are not always made using line 1, but rather using line 2 or line 3 located to the left and above the block.

[0023] For example, as shown in Figure 3, in addition to the direct adjacent line of an adjacent sample (e.g., line 0), one of two non-adjacent reference lines (e.g., line 1 and line 2) can include the input for the VVC intra-prediction. Enhanced compression models (ECMs) allow for the use of more non-adjacent reference lines. When adjacent and non-adjacent reference samples are used, this is called multiple reference line (MRL) prediction.

[0024] For example, the intra modes available for MRL are DC mode and angle prediction mode. In another embodiment, not all of these modes can be combined with MRL for a given block. The MRL mode is always combined with the most probable mode (MPM) in VVC. Such a combination means that when non-adjacent reference lines are used, the intra prediction mode is one of the MPMs. This design of MPM-based MRL prediction modes stems from the observation that non-adjacent reference lines are primarily useful for texture patterns with clear directionality and sharp edges. In these cases, MPM is frequently chosen because there is usually a strong correlation between the texture pattern of adjacent blocks and the texture pattern of the current block. In another embodiment, if a non-MPM is selected for intra prediction, it indicates that the edges in adjacent blocks are inconsistent, and in this case, the usefulness of the MRL prediction mode is expected to be low.

[0025] Furthermore, it has been observed that when the intra-prediction mode is a planar mode, MRL does not provide additional coding gain because the planar mode is typically used for smooth regions. Therefore, the planar mode is excluded in MRL, and the planar mode is always one of the MPMs. The process of angle prediction or DC prediction in MRL is very similar to that of direct adjacent reference lines. In another embodiment, for angle modes with non-integer slopes, a DCT-based interpolation filter (DCTIF) is always used. This design choice is not only proven by experimental results but also consistent with empirical observations (i.e., MRL is most beneficial for sharp edges where directionality is clear), where DCTIF is more suitable because it retains more high frequencies than a smoothing interpolation filter (SIF).

[0026] In one example, from a hardware design perspective, applying the multiple reference lines provided to the method incurs the cost of an additional line buffer, which is used to hold the additional reference lines. In typical hardware designs, the line buffer is part of the on-chip memory architecture for image and video coding, and minimizing the on-chip area of ​​the line buffer is crucial. To address this issue, MRL is disabled and not signaled for coding units tangent to the top boundary of the CTU. In this way, the additional buffer used to hold non-adjacent reference lines is limited to 128 (the width of the maximum unit size).

[0027] Regarding intranet integration For example, to improve the accuracy of intra-prediction, an intra-prediction fusion method is provided. More specifically, if the current block is a luminance block, and the current block is encoded using an angle mode with a non-integer slope (not ISP mode), and the block size (width × height) is greater than 16, then two prediction blocks generated from two different reference lines are "fused," where the fused prediction is a weighted sum of the two prediction blocks. Specifically, the first reference line at index i is obtained by signaling in the bitstream (e.g., the method provided above). i Specify the selected intra prediction mode and use it to generate prediction blocks from the reference line, p(line i ) is denoted as, where p() represents the operation that generates a prediction block from a reference line using a predetermined intra-prediction mode. In the intra-prediction fusion method, the reference line line i+1 The second reference line is implicitly selected. That is, the second reference line is one index position further away from the current block relative to the first reference line. Similarly, the predicted block generated from the second reference line using the same given intra-prediction mode is p(line i+1 This is expressed as ). The weighted sum of the two prediction blocks is obtained as follows and is used as the predictor for the current block.

[0028] p fusion =w0*p(line i +w1*p(line i+1 )) Here, p fusion The fusion prediction is represented by w0 and w1, which are two weighting coefficients that are set to 3 / 4 and 1 / 4 respectively during the experiment.

[0029] About spatial geometric partitioning modes For example, a spatial geometric partitioning mode (SGPM) is provided, which allows a CU to be partitioned into two parts, each capable of using a different intra-prediction mode. The new mode is conceptually similar to the geometric partitioning mode (GPM) applied to inter-prediction of VVCs. In another embodiment, since a large number of partitioning and intra-prediction mode combinations are possible, SGPM uses a different signaling mechanism. To more efficiently represent the required partitioning and prediction information in the bitstream, a candidate list is employed, and candidate indices are signaled in the bitstream. As shown in Figure 5, each candidate in the list can derive a combination of one partitioning mode and two intra-prediction modes.

[0030] For example, as shown in Figure 5, CU510 can be divided into two parts (shown as parts 512 and 513) having different intra-pred mode (e.g., "Intra_pred_mode0" and "Intra_pred_model") using a partition mode (shown as 511, e.g., "Partition_mode"), which can be represented as a syntactic structure 520 having a partition mode index (e.g., "partition_mode_idx") and two intra-pred mode (e.g., "intra_pred_mode0_idx" and "intra_pred_mode0_idx"). In another embodiment, another syntactic structure 530 is further provided that shows a combination 540 having one candidate index (e.g., "sgpm_cand_idx"), which represents a combination of one partition mode (e.g., "partition_mode_idx") and two intra-pred mode (e.g., "intra_pred_mode0_idx" and "intra_pred_mode0_idx").

[0031] For example, a template is used to generate a candidate list. In one example, Figure 6 shows Figure 600, which includes CU610 and one template 620 (shown as two template components 620a and 620b), where the width of template 620 is set to 4. In another embodiment, for SGPM employed in ECM, the template width is set to 1. For each possible combination of one partition mode and two intra-prediction modes, a template prediction is generated using partition weights extended to the template, as shown in Figure 6. These combinations are sorted in ascending order of the cost of the difference transformation absolute sum (SATD) between the template prediction and reconstruction. For example, the size of the candidate list is set to equal 16, and these candidates are considered the most likely SGPM combination for the current block. Both the encoder and decoder use the template to construct the same candidate list. To reduce the complexity of constructing the candidate list, both the number of possible partition modes and the number of possible intra-prediction modes (IPMs) are limited. For example, in the current version of SGPM used in ECM, the number of possible partition modes is limited to a predefined set of 26 partitions, which cover various partition directions and locations. In one example, by trying out various templates associated with the 26 partitions, it is possible to identify the partition with the lowest cost among the 26 partitions.

[0032] For example, two IPM candidate lists corresponding to two SGPM partitions are both constructed by adding available IPM candidates and then reduced to a predetermined limit of three candidates as needed. Some IPM candidates are inherited from intra-inter-GPM modes already employed in ECM. As shown in Figure 7, a GPM with inter-prediction and intra-prediction is shown, where an inter-angle mode parallel to the GPM partition boundary (e.g., parallel mode), an inter-angle mode perpendicular to the GPM partition boundary (e.g., perpendicular mode), and an inter-prediction plane mode (as shown in Figures 7(a) to 7(c)) can be added as available IPM candidates for the SGPM, and as shown in Figure 7(d), an SGPM with intra-prediction and intra-prediction is shown. For example, as shown in Figure 7, available IPM candidate 710 includes a region 711 with a reconstituted sample, a region 713 for intra-prediction, and a region 715 for inter-prediction; available IPM candidate 720 includes a region 721 with a reconstituted sample, a region 723 for intra-prediction, and a region 725 for inter-prediction; available IPM candidate 730 includes a region 731 with a reconstituted sample, a region 733 for intra-prediction, and a region 735 for inter-prediction; and SGPM candidate 740 includes a region 741 with a reconstituted sample, a region 743 for intra-prediction, and a region 745 for inter-prediction.

[0033] Furthermore, an intra-predictive mode can be derived using template-based intra-mode derivation (TIMD), and this intra-predictive mode is used as an available IPM candidate for SGPM. For example, a TIMD intra-predictive mode can be derived using only horizontal and vertical neighbors (e.g., using a top template or left-side template) to form the IPM for SGPM.

[0034] For example, for some CU block sizes, SGPM is implicitly disabled. The range of block sizes for which SGPM can be used (i.e., the range for which the CU-level flag can be signaled to indicate whether to use SGPM) is originally inherited from the intra-inter GPM mode. In the SGPM adopted by ECM, the range of block sizes is further extended to small blocks such as 4×8, 8×4, 4×16, and 16×4 sizes. In short, the block sizes for which SGPM can be used are one of the size limitations such as 4 ≤ width ≤ 64, 4 ≤ height ≤ 64, width < height × 8, height < width × 8, or width × height ≥ 32, where "width" and "height" represent the width and height of the current block.

[0035] For example, as shown in FIG. 8, by using the adaptive SGPM mixing scheme 800, pixels located at the boundary PB (e.g., the GPM division boundary) between two prediction parts can be better predicted, where the weighted average value of these two prediction parts is used in the transitional region around the SGPM partition. The width of the transitional region is called the mixing width. The mixing width is adaptively determined according to the block size. Signaling is not required for adaptive mixing. Further, as shown in FIG. 8, (x, y) are the coordinates of the pixel in the normal direction perpendicular to the boundary PB, d is the distance between the pixel coordinates and the boundary PB, and an angle φ i and ρ j is formed, ω0 indicates the region related to the boundary PB, for example, ω0 indicates the transitional region. Further, as shown in FIG. 8, let the mixing width specified for the GPM tool in VVC and ECM be τ. Then, the adaptive SGPM mixing width is determined as follows based on the width and height of the CU block. When min(width, height) == 4, (l / 2)τ is selected, otherwise, when min(width, height) == 8, τ is selected, otherwise, when min(width, height) == 16, 2τ is selected, otherwise, when min(width, height) == 32, 4τ is selected, and otherwise, 8τ is selected.

[0036] Note that in prior art, one intra-mode is used for each partition of an SGPM block, and a single fixed reference (e.g., reference line 0) is used to generate predictions for a given intra-mode. In this disclosure, coding performance can be further improved by using intra-fusion and MRL in the SGPM block. An example is provided below.

[0037] This disclosure provides a video coding method for coding spatial geometric partitioning modes, an example of which is provided below.

[0038] For example, Figure 9 shows a flowchart of a video encoding method according to an embodiment of the present disclosure, in which an example of video encoding method 900 is provided. Video encoding method 900 includes a box 910 which encodes a candidate index code into a bitstream, where the candidate index code is associated with an intra-partition prediction and a template, the template includes one or more indexed reference lines in a plurality of reference lines having a plurality of reconstructed samples, the plurality of reconstructed samples being spatially adjacent to blocks associated with a spatial geometric partitioning mode (SGPM). For example, instead of a fixed reference line, an index can be used to specify a reference line of one indexed designation to indicate which reference line is used for one or two partitions of an SGPM.

[0039] In response to this, a video decoding method for encoding spatial geometric partitioning modes is provided, and an example is given below.

[0040] For example, Figure 10 shows a flowchart of a video decoding method according to an embodiment of the present disclosure, in which an example of video decoding method 1000 is provided. Video decoding method 1000 includes box 1010, which decodes a candidate index code from a bitstream, where the candidate index code is associated with an intra-partition prediction and a template, the template includes a reference line of one or more index designations in a plurality of reference lines having a plurality of reconstructed samples, the plurality of reconstructed samples being spatially adjacent to blocks associated with a spatial geometric partitioning mode (SGPM).

[0041] In some embodiments, as shown in box 910 of Figure 9 and box 1010 of Figure 10, the candidate index code is associated with a combination of a partition mode index, a first intra-prediction mode index, and a second intra-prediction mode index, where the first intra-prediction mode index indicates the first intra-prediction mode of the first partition of the block based on a single reference line (e.g., a single reference line of an index indicated by an encoder / decoder (not a fixed index)), and the second intra-prediction mode index indicates the second intra-prediction mode of the second partition of the block based on a single reference line. Examples are provided below.

[0042] In Example 1, This disclosure specifies that MRLs can be applied to SGPM blocks. For example, instead of always using line 0, two partitions of an SGPM block can be instructed to use which reference line by specifying one index (e.g., i). Alternatively, two line indices i and j can be specified for two partitions of an SGPM block to indicate which reference line is used for each partition of the SGPM block.

[0043] Specifically, an SGPM block has two partitions. The first partition can use the first intra-mode represented by the valid intra-mode index intra_mode1. The second partition can use the second intra-mode represented by the valid intra-mode index intra_mode2. For a given reference line and intra-prediction mode of a partition in an SGPM block, an intra-prediction called an intra-partition prediction can be generated.

[0044] In some embodiments, as shown in box 910 of Figure 9 and box 1010 of Figure 10, the candidate index code is associated with a combination of a partition mode index, a first intra-prediction mode index, and a second intra-prediction mode index, where the first intra-prediction mode index indicates the first intra-prediction mode of the first partition of the block based on a single reference line indexed by a line index signaled within the bitstream, and the second intra-prediction mode index indicates the second intra-prediction mode of the second partition of the block based on a single reference line. Examples are provided below.

[0045] For the first example, an intra partitioning prediction for the first partition of the SGPM block is generated using reference line line_i and intra prediction mode intra_mode1. An intra partitioning prediction for the second partition of the SGPM block is generated using reference line line_i and intra prediction mode intra_mode2.

[0046] The reference line index i can be signaled by the existing signaling syntax of the MRL. Alternatively, the process of building the SGPM candidate list can be extended to all available combinations of partition mode, two IPM modes for the corresponding partitions, and the reference line index.

[0047] In some embodiments, as shown in box 910 of Figure 9 and box 1010 of Figure 10, the candidate index code is associated with a combination of a partition mode index, a first intra-prediction mode index, and a second intra-prediction mode index, where the first intra-prediction mode index indicates the first intra-prediction mode of the first partition of the block based on a first reference line indexed by a first line index signaled in the bitstream, and the second intra-prediction mode index indicates the second intra-prediction mode of the second partition of the block based on a second reference line indexed by a second line index signaled in the bitstream. Another example is provided below.

[0048] For the second example, an intra-partition prediction for the first partition of the SGPM block is generated using reference line line_i and intra-prediction mode intra_mode1, and an intra-partition prediction for the second partition of the SGPM block is generated using reference line line_j and intra-prediction mode intra_mode2. The reference line indices i and j can be signaled by the existing signaling syntax of MRL. Alternatively, the construction of the SGPM candidate list can be extended to all available combinations of partition mode, two IPM modes for the corresponding partitions, and two reference line indices for the corresponding partitions.

[0049] In Example 2, This disclosure further provides intra-fusion usable for SGPM blocks. More specifically, an SGPM block has two partitions.

[0050] In some embodiments, as shown in box 910 of Figure 9 and box 1010 of Figure 10, the candidate index code is associated with a combination of a partition mode index, a first intra-prediction mode index, and a second intra-prediction mode index, where the first intra-prediction mode index and the second intra-prediction mode index indicate two predetermined intra-prediction modes for two partitions associated with fused intra-partition prediction of a block, and the fused intra-partition prediction is p fusion_partition =w0*p_partition(line i )+w1*p_partition(line i+1 ) is expressed as, where p fusion_partition The function `p_partition()` represents a fused intra partition prediction for each partition within two partitions, where w0 and w1 are two weight coefficients that sum to 1, and `p_partition()` represents an operation function that generates an intra partition prediction using one of two predetermined intra prediction modes based on a predetermined reference line within multiple reference lines. i and line i+1 These are two predetermined reference lines within a set of reference lines, indexed by two indices i and i+1, where index i is either encoded in a bitstream or inferred as a default value, for example, 0 if not encoded.

[0051] For example, using two reference lines (e.g., line 0 and line 1 shown in Figure 3), two corresponding intra partition predictions can be generated for each partition using a predetermined intra prediction mode. Once two intra partition predictions have been generated for a partition, the current partition fusion prediction can be obtained using the following equation, i.e., p fusion_partition =w0*p_partition(line i )+w1*p_partition(line i+1 ) is the case here, p fusion_partitionThis represents the fused intra partition prediction for the current partition, where w0 and w1 are two weight coefficients, which can be set to 3 / 4 and 1 / 4. The first reference line at index i is obtained using the signaling method on the bitstream described above. i Specify ) and use the selected intra prediction mode to generate the intra partition prediction from the reference line p_partition(line i This is denoted as p_partition(), where p_partition() represents the operation of generating an intra-partition prediction from a given reference line using a given intra-prediction mode. The above process is also called SGPM intra-prediction fusion. This SGPM intra-prediction fusion can be applied to all permitted intra-modes, but may be limited to all permitted angular intra-modes, or may be applied to some angular intra-modes with some restrictions (e.g., non-integer inclination angular intra-modes). SGPM intra-prediction fusion may also be limited to a specific CU block size.

[0052] In some embodiments, as shown in box 910 in Figure 9 and box 1010 in Figure 10, index i is predetermined to zero or signaled in the bitstream.

[0053] For example, the reference line i If not specified, the reference line is set to 0 by default. In other words, SGPM intra-prediction fusion always fuses the two intra-split predictions based on line 0 and line 1.

[0054] In some embodiments, as shown in box 910 of Figure 9 and box 1010 of Figure 10, index i and candidate index codes are signaled jointly or individually in one or more syntactic structures of the bitstream. Examples are provided below.

[0055] In another example, enabling MRL and intra-fusion methods for an SGPM block can be signaled jointly or individually at different levels of syntactic structure (e.g., sequence parameter set (SPS), picture header (PH), picture parameter set (PPS), and slice header (SH)).

[0056] In Example 3, This disclosure proposes generating SGPM prediction fusions using two sets of combinations of one partitioning mode and two intra-prediction modes (e.g., a total of two partitioning modes and four intra-prediction modes), where each combination set generates individual CU / block predictions using an existing SGPM method, and the final SGPM prediction fusion is a weighted sum of the two individual predictions.

[0057] In some embodiments, as shown in box 910 in Figure 9 and box 1010 in Figure 10, the candidate index code is associated with two sets of combinations of a split mode index and two intra predictive mode indices, the two sets are associated with a block of SGPM predictive fusion, the SGPM predictive fusion represents the weighted sum of the two sets and two weight parameters, the two weight parameters are two different fixed numbers whose sum is 1. An example is provided below.

[0058] For example, the weight parameters could be fixed numbers such as 1 / 2 and 1 / 2, or 1 / 4 and 3 / 4. Alternatively, other fixed numbers may be used in specific scenarios.

[0059] In some embodiments, as shown in box 910 in Figure 9 and box 1010 in Figure 10, each of the two weight parameters is expressed as a function of the distance between a pixel in the block and a reference pixel in the template. Examples are provided below.

[0060] For example, the weight parameters can further be a function of the relative distance between the current pixel and the reference pixel.

[0061] In some embodiments, as shown in box 910 in Figure 9 and box 1010 in Figure 10, the candidate index code is associated with two combined candidate index components, and the two combined candidate index components represent two sets of combinations of a split-mode index and two intra-predictive-mode indices. Examples are provided below.

[0062] For example, two combinatorial sets can be signaled within a bitstream using two combinatorial candidate indices, and these two combinatorial candidate indices can be determined by the encoder's RDO process.

[0063] In some embodiments, as shown in box 910 of Figure 9 and box 1010 of Figure 10, a candidate index code is associated with a single combined candidate index component, the single combined candidate index component represents the first of two sets of combinations of a split mode index and two intra-predictive mode indices, the second of two sets of combinations of a split mode index and two intra-predictive mode indices is a combination of a specific split mode index and two specific intra-predictive mode indices, the specific split mode index is set as the split mode index associated with the single combined candidate index component, and the two specific intra-predictive mode indices are two intra-predictive mode indices adjacent to the two intra-predictive mode indices associated with the single combined candidate index component, the single combined candidate index component is one candidate index in the list. An example is provided below.

[0064] As another example, the current SGPM method signals a first combination set by sending only one candidate index in the bitstream. The second combination set then uses the same partition mode derived from the signaled candidate index and two adjacent intra modes derived from the signaled candidate index (e.g., two intra modes derived from the signaled candidate index +1 or -1).

[0065] In some embodiments, as shown in box 910 of Figure 9 and box 1010 of Figure 10, there is a fixed offset distance between two specific intra-predictive mode indices and two intra-predictive mode indices associated with a single combination candidate index component. Examples are provided below.

[0066] For example, these two adjacent intra-modes can be located either within or outside the candidate list, and can be located on either side by adding a fixed offset, provided that both the encoder and decoder follow the same predetermined rules.

[0067] In some embodiments, as shown in boxes 910 in Figure 9 and 1010 in Figure 10, a candidate index code is associated with a single combined candidate index component, where the single combined candidate index component represents the first of two sets of combinations of a split mode index and two intra-predictive mode indices, the second of two sets of combinations of a split mode index and two intra-predictive mode indices is a combination of a specific split mode index and two specific intra-predictive mode indices, where the specific split mode index is set as the split mode index associated with the single combined candidate index component, and the two specific intra-predictive mode indices are set as two intra-predictive mode indices associated with other candidate indices in the list, where the split mode index of the other candidate indices is equal to the split mode index associated with the single combined candidate index component. An example is provided below.

[0068] As another example, the two intra modes can be set to any candidate intra mode in the list, and such any candidate split mode is the same as the split mode associated with the combined index signaled in the bitstream.

[0069] In some embodiments, as shown in boxes 910 in Figure 9 and 1010 in Figure 10, it is determined that there are multiple candidate indices in the list, and in response that the split-mode indices of the multiple candidate indices are equal to the split-mode indices associated with a single combined candidate index component, two specific intra-prediction-mode indices are set as two intra-prediction-mode indices associated with one candidate index in the list, and this one candidate index minimizes the difference transformation absolute sum (SATD) cost between prediction and reconstruction of the template. An example is provided below.

[0070] For example, if multiple candidates have the same partitioning mode, the candidate with the smallest SATD cost will provide two intra modes to the second combination set.

[0071] In some embodiments, as shown in box 910 of Figure 9 and box 1010 of Figure 10, a candidate index code is associated with a single combined candidate index component, the single combined candidate index component represents the first of two sets of combinations of a split mode index and two intra-predictive mode indices, the second of two sets of combinations of a split mode index and two intra-predictive mode indices is a combination of a specific split mode index and two specific intra-predictive mode indices, the specific split mode index is one split mode index adjacent to the split mode index associated with the single combined candidate index component, the single combined candidate index component is one candidate index in the list, and the two specific intra-predictive mode indices are set as two intra-predictive mode indices associated with the single combined candidate index component. An example is provided below.

[0072] As another example, the current SGPM method signals a first combination set by sending only one candidate index in the bitstream. The second combination set then uses the same intra-mode derived from the signaled candidate index and a partition mode adjacent to the partition mode derived from the signaled candidate index (e.g., a partition mode derived from the signaled candidate index +1 or -1).

[0073] In some embodiments, as shown in box 910 of Figure 9 and box 1010 of Figure 10, there is a fixed offset distance between a particular splitting prediction mode index and the splitting mode index associated with a single combination candidate index component. Examples are provided below.

[0074] For example, these two adjacent split modes can be located either within or outside the candidate list, and can be positioned on either side by adding a fixed offset, but both the encoder and decoder must follow the same predefined rules.

[0075] In some embodiments, as shown in box 910 of Figure 9 and box 1010 of Figure 10, a candidate index code is associated with a single combined candidate index component, where the single combined candidate index component represents the first of two sets of combinations of a split mode index and two intra-predictive mode indices, the second of two sets of combinations of a split mode index and two intra-predictive mode indices is a combination of a specific split mode index and two specific intra-predictive mode indices, where the specific split mode index is set as one split mode index associated with other candidate indices in the list, the two intra-predictive mode indices of other candidate indices are equal to the two intra-predictive mode indices associated with the single combined candidate index component, and the two specific intra-predictive mode indices are set as the two intra-predictive mode indices associated with the single combined candidate index component. An example is provided below.

[0076] As another example, the split mode can be set to the split mode of any candidate in the list, and the intra mode of that candidate is the same as the intra mode associated with the combination index signaled in the bitstream.

[0077] In some embodiments, as shown in box 910 of Figure 9 and box 1010 of Figure 10, it is determined that there are multiple candidate indices in the list, and in response that two intra-prediction mode indices of the multiple candidate indices are equal to the split mode indices associated with a single combined candidate index component, a particular split mode indice is set as a single split mode indice associated with one candidate index in the list, and this single candidate index minimizes the difference transformation absolute sum (SATD) cost between prediction and reconstruction of the template. An example is provided below.

[0078] For example, if multiple candidates have the same prediction mode, the candidate with the smallest SATD cost will provide a partitioning mode to the second combination set.

[0079] In some embodiments, as shown in box 910 of Figure 9 and box 1010 of Figure 10, a candidate index code is associated with a single combined candidate index component, which represents the first of two sets of combinations of a split-mode index and two intra-prediction-mode indices, the second of two sets of combinations of a split-mode index and two intra-prediction-mode indices being a combination of a specific split-mode index and two specific intra-prediction-mode indices, and the combination of a specific split-mode index and two specific intra-prediction-mode indices is associated with one candidate index in the list, which minimizes the difference transformation absolute sum (SATD) cost between prediction and reconstruction of the template. Examples are provided below.

[0080] As another example, the current SGPM method signals the first set of combinations by sending only one candidate index in the bitstream. The second set of combinations then always uses the candidate with the smallest SATD in the list.

[0081] Furthermore, any suitable computing system can be used to perform video encoding operations (e.g., the operation of a video encoder as described herein) or video decoding operations (e.g., the operation of a video decoder as described herein). For example, Figure 11 shows an example of a computing device 1100, which comprises a processor 1110, the processor 1110 coupled to memory 1120, and which can perform the methods described herein (e.g., a video encoding method or a video decoding method).

[0082] In some embodiments, the computing device comprises a processor, which is coupled to memory and configured to execute program instructions stored in memory to perform operations in a video encoding method related to an encoder or a video decoding method related to a decoder.

[0083] For example, a processor may include a microprocessor, an application-specific integrated circuit ("ASIC"), a state machine, or other processing equipment, and for example, a processor may include one or more processing units. Such a processor may include, or communicate with, a computer-readable medium for storing instructions, and when an instruction is executed by the processor, the instruction causes the processor to perform the operations described herein. Memory may include any suitable non-temporary computer-readable medium.

[0084] For example, computer-readable media includes any electronic, optical, magnetic, or other memory device that can provide computer-readable instructions or other program code to a processor. Non-exclusive examples of computer-readable media include magnetic disks, memory chips, ROM, RAM, ASICs, configured processors, optical memory, magnetic tape or other magnetic memory, or any other medium from which a computer processor can read instructions. Instructions may include processor-specific instructions generated by a compiler and / or interpreter based on code written in any suitable computer programming language (including, for example, C, C++, C#, Visual Basic, Java, Python, Perl, JavaScript, and ActionScript).

[0085] In some embodiments, the present disclosure provides a video encoding system comprising a processor and memory coupled to the processor, wherein the processor executes program instructions stored in the memory to execute one of the video encoding methods described above.

[0086] In some embodiments, the Disclosure provides a non-temporary computer-readable medium in which a processor executes and stores program code causing the processor to execute one of the above video encoding methods.

[0087] In some embodiments, the Disclosure provides a video decoding system comprising a processor and memory coupled to the processor, wherein the processor executes program instructions stored in the memory to execute one of the video decoding methods described above.

[0088] In some embodiments, the Disclosure provides a non-temporary computer-readable medium which is executed by a processor and stores program code causing the processor to execute one of the above video decoding methods.

[0089] Those skilled in the art will understand that each unit, algorithm, and step described and disclosed in the embodiments of this disclosure is implemented by electronic hardware or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the application conditions and the design requirements of the technical solution. Those skilled in the art may implement the functions using different methods for each specific application, and such implementations should not exceed the scope of this disclosure. As those skilled in the art will understand, the operating processes of the systems, devices, and units in the above embodiments are almost identical and can therefore be referenced. For the sake of clarity and brevity, these operating processes will not be described in detail.

[0090] It can be understood that the systems, devices, and methods disclosed in the embodiments of this disclosure can be implemented in other ways. The embodiments described above are illustrative only. While the division of units is based on logical functions, other division methods may exist in implementation. Multiple units or components may be integrated or combined into another system, and some features may be omitted or skipped. In other embodiments, the mutual coupling, direct coupling, or communication coupling shown or described may operate indirectly, or communicate electrically, mechanically, or otherwise, through some ports, devices, or units.

[0091] Units separated for illustrative purposes may be physically separated units or not. The displayed units may be physical units or not physical units, i.e., located in one place or distributed across multiple network units. Some or all of these units are used depending on the purpose of the embodiment. Furthermore, each functional unit in each embodiment may be integrated into a single processing unit, which may be a physically independent unit or integrated into a single processing unit comprising two or more units.

[0092] When a software function unit is implemented, used, and sold as a product, the software function unit can be stored on a readable storage medium in a computer. Based on this understanding, the technical solutions provided in this disclosure can be implemented in essence or in part in the form of a software product, or some of the technical solutions that are beneficial to the prior art can be implemented in the form of a software product. A software product in a computer is stored on a storage medium and contains a number of commands for a computing device (e.g., a personal computer, server, or network device) to perform all or part of the steps disclosed in embodiments of this disclosure. The storage medium includes USB disks, mobile hard disks, read-only memory (ROM), random access memory (RAM), floppy disks, or other media capable of storing program code.

[0093] While this disclosure describes a combination of what are considered to be the most practical and preferred embodiments, it should be understood that this disclosure is not limited to the disclosed embodiments and is intended to cover each implemented layout without departing from the broadest interpretation of the appended claims.

Claims

1. A video encoding method, A video coding method comprising encoding a candidate index code into a bitstream, wherein the candidate index code is associated with an intra-partition prediction and a template, the template includes one or more reference lines of index designation within a plurality of reference lines having a plurality of reconstructed samples, the plurality of reconstructed samples being spatially adjacent to blocks associated with a spatial geometric partitioning mode (SGPM).

2. The candidate index code is associated with a combination of a partition mode index, a first intra-prediction mode index, and a second intra-prediction mode index, wherein the first intra-prediction mode index indicates a first intra-prediction mode of the first partition of the block based on a single reference line indexed by a line index signaled within the bitstream, and the second intra-prediction mode index indicates a second intra-prediction mode of the second partition of the block based on the single reference line. The video encoding method according to claim 1.

3. The candidate index code is associated with a combination of a partition mode index, a first intra-prediction mode index, and a second intra-prediction mode index, wherein the first intra-prediction mode index indicates a first intra-prediction mode of the first partition of the block based on a first reference line indexed by a first line index signaled in the bitstream, and the second intra-prediction mode index indicates a second intra-prediction mode of the second partition of the block based on a second reference line indexed by a second line index signaled in the bitstream. The video encoding method according to claim 1.

4. The candidate index code is associated with a combination of a partition mode index, a first intra-prediction mode index, and a second intra-prediction mode index, wherein the first intra-prediction mode index and the second intra-prediction mode index indicate two predetermined intra-prediction modes for two partitions of the block associated with fused intra-partition prediction, and the fused intra-partition prediction is p fusion_partition =w 0 *p_partition(line i )+w 1 *p_partition(line i+1 ) Represented as follows, pfusion_partition represents the fused intra partition prediction for each partition within the two partitions, w0 and w1 are two weight coefficients that sum to 1, p_partition() represents an operation function that generates an intra partition prediction using one of the two predetermined intra partition prediction modes based on predetermined reference lines within the plurality of reference lines, and linei and linei+1 are two predetermined reference lines within the plurality of reference lines that are indexed by two indices i and i+1. The video encoding method according to claim 1.

5. The index i is predetermined to be zero, or is signaled within the bitstream. The video encoding method according to claim 4.

6. The index i and the candidate index code are signaled jointly or individually in one or more syntactic structures of the bitstream. The video encoding method according to claim 5.

7. The candidate index code is associated with two sets of combinations of a split mode index and two intra-predictive mode indices, the two sets are associated with the SGPM prediction fusion of the block, the SGPM prediction fusion represents the weighted sum of the two sets and two weight parameters, the two weight parameters are two different fixed numbers whose sum is 1. The video encoding method according to claim 1.

8. Each of the two weight parameters is expressed as a function of the distance between the pixel in the block and the reference pixel in the template. The video encoding method according to claim 7.

9. The candidate index code is associated with two combined candidate index components, and the two combined candidate index components represent the two sets of combinations of the partition mode index and the two intra-predictive mode indices. The video encoding method according to claim 7.

10. The candidate index code is associated with a single combination candidate index component, the single combination candidate index component represents a first set of two sets of combinations of the split mode index and the two intra-prediction mode indices, the second set of two sets of combinations of the split mode index and the two intra-prediction mode indices is a combination of a specific split mode index and two specific intra-prediction mode indices, the specific split mode index is set as the split mode index associated with the single combination candidate index component, the two specific intra-prediction mode indices are two intra-prediction mode indices adjacent to the two intra-prediction mode indices associated with the single combination candidate index component, and the single combination candidate index component is one candidate index in the list. The video encoding method according to claim 7.

11. The two specific intra-predictive mode indices and the two intra-predictive mode indices associated with the single combination candidate index component are separated by a fixed offset. The video encoding method according to claim 10.

12. The candidate index code is associated with a single combination candidate index component, the single combination candidate index component represents a first set of two sets of combinations of the split mode index and the two intra-prediction mode indices, the second set of two sets of combinations of the split mode index and the two intra-prediction mode indices is a combination of a specific split mode index and two specific intra-prediction mode indices, the specific split mode index is set as the split mode index associated with the single combination candidate index component, the two specific intra-prediction mode indices are set as two intra-prediction mode indices associated with other candidate indices in the list, the split mode index of the other candidate indices is equal to the split mode index associated with the single combination candidate index component. The video encoding method according to claim 7.

13. It is determined that there are multiple candidate indexes in the list, and in response that the split mode index of the multiple candidate indexes is equal to the split mode index associated with the single combined candidate index component, the two specific intra-prediction mode indexes are set as two intra-prediction mode indexes associated with one candidate index in the list, and the one candidate index minimizes the difference transformation absolute sum (SATD) cost between prediction and reconstruction of the template. The video encoding method according to claim 12.

14. The candidate index code is associated with a single combination candidate index component, the single combination candidate index component represents a first set of two sets of combinations of the split mode index and the two intra-prediction mode indices, the second set of two sets of combinations of the split mode index and the two intra-prediction mode indices is a combination of a specific split mode index and two specific intra-prediction mode indices, the specific split mode index is a split mode index adjacent to the split mode index associated with the single combination candidate index component, the single combination candidate index component is a single candidate index in the list, and the two specific intra-prediction mode indices are set as the two intra-prediction mode indices associated with the single combination candidate index component. The video encoding method according to claim 7.

15. The aforementioned specific split mode index and the split mode index associated with the single combination candidate index component are separated by a fixed offset. The video encoding method according to claim 14.

16. The candidate index code is associated with a single combination candidate index component, the single combination candidate index component represents a first set of two sets of combinations of the split mode index and the two intra-prediction mode indices, the second set of two sets of combinations of the split mode index and the two intra-prediction mode indices is a combination of a specific split mode index and two specific intra-prediction mode indices, the specific split mode index is set as a single split mode index associated with another candidate index in the list, the two intra-prediction mode indices of the other candidate index are equal to the two intra-prediction mode indices associated with the single combination candidate index component, and the two specific intra-prediction mode indices are set as the two intra-prediction mode indices associated with the single combination candidate index component. The video encoding method according to claim 7.

17. It is determined that there are multiple candidate indices in the list, and in response that two of the multiple candidate indices' intra-prediction mode indices are equal to the split-mode indices associated with the single combined candidate index component, the particular split-mode indice is set as a single split-mode indice associated with one of the candidate indices in the list, and the single candidate indice minimizes the difference transformation absolute sum (SATD) cost between prediction and reconstruction of the template. The video encoding method according to claim 16.

18. The candidate index code is associated with a single combination candidate index component, the single combination candidate index component represents a first set of two sets of combinations of the split mode index and the two intra-prediction mode indices, the second set of two sets of combinations of the split mode index and the two intra-prediction mode indices is a combination of a specific split mode index and two specific intra-prediction mode indices, the specific split mode index and the two specific intra-prediction mode indices is associated with a single candidate index in a list, the single candidate index minimizes the differential transformation absolute sum (SATD) cost between prediction and reconstruction of the template. The video encoding method according to claim 7.

19. A video encoding system, Processor and A video encoding system comprising a memory coupled to the processor, wherein the processor executes program instructions stored in the memory to perform the video encoding method according to any one of claims 1 to 18.

20. A non-temporary computer-readable medium having a processor that stores program code for causing the processor to perform the video encoding method described in any one of claims 1 to 18.

21. A video decoding method, A video decoding method comprising decoding candidate index codes from a bitstream, wherein the candidate index codes are associated with an intra-partitioning prediction and a template, the template includes one or more reference lines of index designation within a plurality of reference lines having a plurality of reconstructed samples, and the plurality of reconstructed samples are spatially adjacent to blocks associated with a spatial geometric partitioning mode (SGPM).

22. The candidate index code is associated with a combination of a partition mode index, a first intra-prediction mode index, and a second intra-prediction mode index, wherein the first intra-prediction mode index indicates a first intra-prediction mode of the first partition of the block based on a single reference line indexed by a line index signaled within the bitstream, and the second intra-prediction mode index indicates a second intra-prediction mode of the second partition of the block based on the single reference line. The video decoding method according to claim 21.

23. The candidate index code is associated with a combination of a partition mode index, a first intra-prediction mode index, and a second intra-prediction mode index, wherein the first intra-prediction mode index indicates a first intra-prediction mode of the first partition of the block based on a first reference line indexed by a first line index signaled in the bitstream, and the second intra-prediction mode index indicates a second intra-prediction mode of the second partition of the block based on a second reference line indexed by a second line index signaled in the bitstream. The video decoding method according to claim 21.

24. The candidate index code is associated with a combination of a partition mode index, a first intra-prediction mode index, and a second intra-prediction mode index, wherein the first intra-prediction mode index and the second intra-prediction mode index indicate two predetermined intra-prediction modes for two partitions of the block associated with fused intra-partition prediction, and the fused intra-partition prediction is p fusion_partition =w 0 *p_partition(line i )+w 1 *p_partition(line i+1 ) Represented as follows, pfusion_partition represents the fused intra partition prediction for each partition within the two partitions, w0 and w1 are two weight coefficients that sum to 1, p_partition() represents an operation function that generates an intra partition prediction using one of the two predetermined intra partition prediction modes based on predetermined reference lines within the plurality of reference lines, and linei and linei+1 are two predetermined reference lines within the plurality of reference lines that are indexed by two indices i and i+1. The video encoding method according to claim 21.

25. The index i is predetermined to be zero, or is signaled within the bitstream. The video decoding method according to claim 24.

26. The index i and the candidate index code are signaled jointly or individually in one or more syntactic structures of the bitstream. The video decoding method according to claim 25.

27. The candidate index code is associated with two sets of combinations of a split mode index and two intra-predictive mode indices, the two sets are associated with the SGPM prediction fusion of the block, the SGPM prediction fusion represents the weighted sum of the two sets and two weight parameters, the two weight parameters are two different fixed numbers whose sum is 1. The video decoding method according to claim 21.

28. Each of the two weight parameters is expressed as a function of the distance between the pixel in the block and the reference pixel in the template. The video decoding method according to claim 27.

29. The candidate index code is associated with two combined candidate index components, and the two combined candidate index components represent the two sets of combinations of the partition mode index and the two intra-predictive mode indices. The video decoding method according to claim 27.

30. The candidate index code is associated with a single combination candidate index component, the single combination candidate index component represents a first set of two sets of combinations of the split mode index and the two intra-prediction mode indices, the second set of two sets of combinations of the split mode index and the two intra-prediction mode indices is a combination of a specific split mode index and two specific intra-prediction mode indices, the specific split mode index is set as the split mode index associated with the single combination candidate index component, and the two specific intra-prediction mode indices are two intra-prediction mode indices adjacent to the two intra-prediction mode indices associated with the single combination candidate index component as one candidate index in the list. The video decoding method according to claim 27.

31. The two specific intra-predictive mode indices and the two intra-predictive mode indices associated with the single combination candidate index component are separated by a fixed offset. The video decoding method according to claim 30.

32. The candidate index code is associated with a single combination candidate index component, the single combination candidate index component represents a first set of two sets of combinations of the split mode index and the two intra-prediction mode indices, the second set of two sets of combinations of the split mode index and the two intra-prediction mode indices is a combination of a specific split mode index and two specific intra-prediction mode indices, the specific split mode index is set as the split mode index associated with the single combination candidate index component, the two specific intra-prediction mode indices are set as two intra-prediction mode indices associated with other candidate indices in the list, the split mode index of the other candidate indices is equal to the split mode index associated with the single combination candidate index component. The video decoding method according to claim 27.

33. It is determined that there are multiple candidate indexes in the list, and in response that the split mode index of the multiple candidate indexes is equal to the split mode index associated with the single combined candidate index component, the two specific intra-prediction mode indexes are set as two intra-prediction mode indexes associated with one candidate index in the list, and the one candidate index minimizes the difference transformation absolute sum (SATD) cost between prediction and reconstruction of the template. The video decoding method according to claim 32.

34. The candidate index code is associated with a single combination candidate index component, the single combination candidate index component represents a first set of two sets of combinations of the split mode index and the two intra-prediction mode indices, the second set of two sets of combinations of the split mode index and the two intra-prediction mode indices is a combination of a specific split mode index and two specific intra-prediction mode indices, the specific split mode index is a split mode index adjacent to the split mode index associated with the single combination candidate index component, the single combination candidate index component is a single candidate index in the list, and the two specific intra-prediction mode indices are set as the two intra-prediction mode indices associated with the single combination candidate index component. The video decoding method according to claim 27.

35. The aforementioned specific split mode index and the split mode index associated with the single combination candidate index component are separated by a fixed offset. The video decoding method according to claim 34.

36. The candidate index code is associated with a single combination candidate index component, the single combination candidate index component represents a first set of two sets of combinations of the split mode index and the two intra-prediction mode indices, the second set of two sets of combinations of the split mode index and the two intra-prediction mode indices is a combination of a specific split mode index and two specific intra-prediction mode indices, the specific split mode index is set as a single split mode index associated with another candidate index in the list, the two intra-prediction mode indices of the other candidate index are equal to the two intra-prediction mode indices associated with the single combination candidate index component, and the two specific intra-prediction mode indices are set as the two intra-prediction mode indices associated with the single combination candidate index component. The video decoding method according to claim 27.

37. It is determined that there are multiple candidate indices in the list, and in response that two of the multiple candidate indices' intra-prediction mode indices are equal to the split-mode indices associated with the single combined candidate index component, the particular split-mode indice is set as a single split-mode indice associated with one of the candidate indices in the list, and the single candidate indice minimizes the difference transformation absolute sum (SATD) cost between prediction and reconstruction of the template. The video decoding method according to claim 36.

38. The candidate index code is associated with a single combination candidate index component, the single combination candidate index component represents a first set of two sets of combinations of the split mode index and the two intra-prediction mode indices, the second set of two sets of combinations of the split mode index and the two intra-prediction mode indices is a combination of a specific split mode index and two specific intra-prediction mode indices, the specific split mode index and the two specific intra-prediction mode indices is associated with a single candidate index in a list, the single candidate index minimizes the differential transformation absolute sum (SATD) cost between prediction and reconstruction of the template. The video decoding method according to claim 27.

39. A video decoding system, Processor and A video decoding system comprising a memory coupled to the processor, wherein the processor executes program instructions stored in the memory to perform the video decoding method according to any one of claims 21 to 38.

40. A non-temporary computer-readable medium having a processor that stores program code for causing the processor to perform the video decoding method according to any one of claims 21 to 38.

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