Method and apparatus for multi-hypothesis prediction mode with different chroma format for video coding

Abstract

A method and apparatus for video coding are disclosed. According to the method, a current block is received at an encoder side or compressed data including the current block is received at a decoder side, wherein the current block includes one luma block and one or more chroma blocks, and the current block is generated by partitioning an image region into one or more partition blocks containing the current block using a single partition tree. A target coding mode of the current block is determined. Then, the current block is encoded or decoded according to the target coding mode, wherein if the target coding mode corresponds to a multi-hypothesis prediction mode and a width, a height, or an area of the current block is less than a threshold, additional hypotheses for prediction of the one or more chroma blocks are disabled.

Description

[0001] Cross-referencing

[0002] This invention claims priority to U.S. Provisional Patent Application No. 62 / 907,699, filed September 29, 2019. The entire contents of that U.S. Provisional Patent Application are incorporated herein by reference. Technical Field

[0003] This invention relates to prediction in video codecs using CIIP (Combined Inter / Intra Prediction). In particular, this invention discloses techniques for improving processing throughput for small block sizes. Background Technology

[0004] High Efficiency Video Coding (HEVC) is a new international video coding standard developed by the Joint Collaborative Video Coding Team (JCT-VC). HEVC is based on a hybrid block-based motion-compensated DCT transform coding architecture. The basic unit of compression is called a coding unit (CU), which is a 2Nx2N square block. Each CU can be recursively divided into four smaller CUs until a predefined minimum size is reached. Each CU contains one or more prediction units (PUs).

[0005] To achieve optimal coding efficiency in HEVC's hybrid codec architecture, each PU has two prediction modes (i.e., intra-frame prediction and inter-frame prediction). For intra-frame prediction mode, spatially adjacent reconstructed pixels can be used to generate orientation predictions.

[0006] Following the development of the HEVC standard, another merged video coding standard, called Universal Video Coding (VVC), is being developed under the guidance of the Joint Video Exploration Group (JVET) of ITU-T SG 16WP 3 and ISO / IEC JTC 1 / SC 29 / WG 11. Various new codecs, as well as some existing ones, have been evaluated for VVC.

[0007] In the VTM (VVC Test Model) software, when a CU is encoded in merged mode, and if the CU contains at least 64 luma samples (i.e., CU width x CU height equal to or greater than 64), an additional flag (CIIP flag) is signaled at the CU level to indicate whether a combined inter-frame / intra-frame prediction (CIIP) mode is applied to the current CU. To form a CIIP prediction, the intra-frame prediction mode is first obtained or implicitly assigned from two additional syntax elements. For example, a planar mode is implicitly specified as the intra-frame prediction mode. As another example, up to four possible intra-frame prediction modes can be used: DC, planar, horizontal, or vertical. Then, the inter-frame prediction (existing prediction assumptions) and intra-frame prediction signals (other prediction assumptions) are derived using the regular intra-frame and inter-frame decoding process. Finally, a weighted average of the inter-frame and intra-frame prediction signals is taken to obtain the CIIP prediction. A more detailed description of the algorithm can be found in JVET-L0100 (M.-S. Chiang, et al., “CE10.1.1: Multi-hypothesis prediction for improving AMVP mode, skip or merge mode, and intra mode,” ITU-T SG 16WP 3 and ISO / IEC JTC).

[0008] 1 / SC 29 / WG 11,12th Meeting: Macao, CN, Oct. 2018, Document: JVET-L0100).

[0009] Triangular Prediction

[0010] For VTM, in JVET-L0124 (R.-L. Liao, et al., “CE10.3.1.b: Triangular prediction unit mode,” ITU-T SG 16WP 3 and ISO / IEC JTC)

[0011] 1 / SC 29 / WG 11,12th Meeting: Macao, CN, Oct. 2018, Document: JVET-L0124) and JVET-L0208 (T.Poirier, et al., "CE10 related: multiple prediction unit shapes," ITU-T SG 16WP 3and ISO / IEC JTC 1 / SC

[0012] In 29 / WG 11,12th Meeting: Macao, CN, Oct. 2018, Document: JVET-L0208, a scheme for the Triangular Prediction Unit (TPM) model was proposed. The concept involves introducing new triangular partitions for motion compensation prediction. For example... Figure 1 As shown, labels 110 and 120 indicate that the CU is divided into two triangular prediction units, PU1 and PU2, along the diagonal or opposite direction. Each triangular prediction unit in the CU performs inter-frame prediction using its own single-predictive motion vector and a reference frame. After predicting the triangular prediction units, adaptive weighting is performed on the diagonal edges. Then, the transform and quantization process is applied to the entire CU. Note that this mode is only applied to skip and merge modes. An additional flag is signaled to indicate whether TPM has been applied.

[0013] Adaptive weighted processing

[0014] After predicting each triangular prediction unit, an adaptive weighting process is applied to the diagonal edges between two triangular prediction units to arrive at the final prediction for the entire CU. Two sets of weighting factors are listed below:

[0015] The first weighting factor group: {7 / 8, 6 / 8, 4 / 8, 2 / 8, 1 / 8} and {7 / 8, 4 / 8, 1 / 8} are used for luminance and chrominance samples, respectively;

[0016] The second weighting factor group: {7 / 8, 6 / 8, 5 / 8, 4 / 8, 3 / 8, 2 / 8, 1 / 8} and {6 / 8, 4 / 8, 2 / 8} were used for luminance and chrominance samples, respectively.

[0017] Based on a comparison of the motion vectors of two triangular prediction units, a weighting factor group is selected. A second weighting factor group is used when the reference images of the two triangular prediction units are different from each other or when the difference in their motion vectors is greater than 16 pixels. Otherwise, the first weighting factor group is used. Figure 2 An example is shown, illustrating a weighting factor of 210 for the luma block and a weighting factor of 220 for the chroma block. A more detailed description of the algorithm can be found in JVET-L0124 and JVET-L0208.

[0018] Geometric Merge (GEO)

[0019] JVET-P0068 (H.Gao, et al., "CE4: CE4-1.1, CE4-1.2 and CE4-1.14: GeometricMerge Mode (GEO)", ITU-T SG 16WP 3and ISO / IEC JTC

[0020] 1 / SC 29 / WG 11, 16th Meeting: Geneva, CH, 1–11 October 2019, Document: P0068) proposed the geometric merging mode (also known as the geometric partitioning mode, GPM), which uses the same predictor mixing concept as TPM and extends it to mix up to 140 different modes with up to 32 angles and 5 distance offsets.

[0021] In P0068, 140 modes are defined as CE4-1.1. To further reduce complexity, GEO was tested with 108 modes and 80 modes in CE4-1.2. In CE4-1.14, a simplified motion storage similar to TPM was tested.

[0022] Figure 3A The partition shapes (311-312) used for TPM in VTM-6.0 are shown. Figure 3B Additional shapes (313-319) proposed for non-rectangular inter-frame blocks are shown.

[0023] Similar to TPM, single prediction blocks of 8×8 or larger are allowed to have GEO partitions proposed for inter-frame predictions, so as to have the same storage bandwidth utilization on the decoder side as dual prediction blocks. Motion vector predictions for GEO partitions are aligned with TPM. Similarly, TPM blending between the two predictions is applied to the internal boundaries.

[0024] The segmentation boundary of the geometric merging pattern is determined by angle. and distance offset Description, such as Figure 4 As shown. Angle Represents the quantized angle between 0 and 360 degrees, distance offset Indicates the maximum distance The quantization offset is also excluded. Additionally, segmentation directions that overlap with binary tree segmentation and TPM segmentation are excluded.

[0025] GEO Angle and Distance Quantization

[0026] angle Quantization is performed between 0 and 360 degrees using a fixed step size. In CE4-1.1, CE4-1.2 with 108 modes, and CE4-1.14, angles are quantized between 0 and 360 degrees with a step size of 11.25 degrees. This results in a total of 32 angles, such as Figure 5A As shown.

[0027] In CE4-1.2, which has 80 modes, the angle Quantization is still performed in steps of 11.25 degrees; however, since the target object and motion are mostly horizontal in natural values, angles close to the vertical direction (e.g., those close to the horizontal segmentation boundary) are removed. Figure 5B The diagram shows the angle of reduction with 24 values. From the maximum possible distance... Quantize distance with fixed step size i. The value of can be geometrically derived from equation (1), where w or h equals 8 and is scaled by the shorter side length in log2. For When the temperature is 0 degrees, Equals w / 2, for When the angle is equal to 90 degrees, It equals h / 2. The "1.0" sample is shifted backward to avoid the segmentation boundary being too close to the corner.

[0028]

[0029] In CE4-1.1 and CE4-1.14, distance Quantization is performed in 5 steps. Combining 32 angles, there are a total of 140 segmentation patterns, excluding binary tree and TPM segmentation. In CE4-1.2-, distance... Quantization is performed in 4 steps. Combining 32 angles, a total of 108 segmentation patterns are obtained, excluding binary tree and TPM segmentation. In CE4-1.2, distance... The quantization process involves four steps. Combining 24 perspectives, there are a total of 80 segmentation patterns, excluding binary tree and TPM segmentation.

[0030] Mode signaling

[0031] According to the recommended approach, the GEO mode, together with the TPM mode, is sent as an additional merging mode, as shown in Table 1.

[0032] The grammatical elements proposed in Table 1

[0033]

[0034]

[0035] Signals are generated using four CABAC context models, the first three of which are derived from the patterns of the blocks above and to the left, and the fourth is derived from the aspect ratio of the current block. Indicates whether the current block uses GEO mode or TPM mode, similar to the "most probable mode" flag.

[0036] Used as an index for a lookup table that stores angles. and distance Yes. geo_partition_idx uses truncated binary encoding and performs binary conversion using a bypass. Summary of the Invention

[0037] A method and apparatus for video encoding and decoding are disclosed. According to the method, a current block is received at the encoder side, or compressed data including the current block is received at the decoder side, wherein the current block comprises a luma block and one or more chroma blocks, the current block being generated through segmentation. An image region is divided into one or more partition blocks including the current block using a single partition tree, and one or more encoding / decoding tools including multi-hypothesis prediction modes are allowed for the current block. The single partition tree is a single tree for luma and chroma. A target encoding / decoding mode for the current block is determined. The current block is then encoded or decoded according to the target encoding / decoding mode, wherein additional hypotheses for the prediction of the one or more chroma blocks are disabled if the target encoding / decoding mode corresponds to a multi-hypothesis prediction mode and the width, height, or area of ​​the target is less than a threshold.

[0038] In one embodiment, if the width of the one or more chroma blocks is less than a threshold and the threshold is equal to 4, then additional assumptions for the prediction of the one or more chroma blocks are disabled.

[0039] In one embodiment, the multi-hypothesis prediction mode corresponds to the combined inter-frame / intra-frame prediction (CIIP) mode. In another embodiment, the multi-hypothesis prediction mode corresponds to the triangular prediction mode (TPM). In yet another embodiment, the multi-hypothesis prediction mode corresponds to the geometric merging mode (GEO).

[0040] In one embodiment, the current block is in chroma format 4:4:4, 4:2:2, or 4:2:0.

[0041] In one embodiment, the threshold is implicitly predefined in the standard or signaled by a transform unit (TU) or transform block (TB), coding unit (CU) or coding block (CB), coding tree unit (CTU) or coding tree block (CTB), tile, tile group, sequence parameter set (SPS), picture parameter set (PPS), or picture level of the video bitstream.

[0042] In one embodiment, the image region corresponds to a coding tree unit (CTU). Attached Figure Description

[0043] Figure 1An example of TPM (Triangular Prediction Mode) is shown, where the CU is divided into two triangular prediction units in either the diagonal direction or the opposite diagonal direction. Inter-frame prediction is performed on each triangular prediction unit in the CU using its own unidirectional predicted motion vector and reference frame index to generate predictions based on single prediction candidates.

[0044] Figure 2 An example of an adaptive weighting process is shown, illustrating the weighting of the luminance block (left) and the chrominance block (right).

[0045] Figure 3A This describes the partition shape of the Triangular Prediction Model (TPM) disclosed in VTM-6.0. Figure 3B Other shapes used for geometric merging patterns are shown in the diagram.

[0046] Figure 4 It shows the angle and distance offset The segmentation boundary of the described geometric merging pattern.

[0047] Figure 5A This shows the angle quantized from 0 to 360 degrees in steps of 11.25 degrees. For example, this results in a total of 32 angles.

[0048] Figure 5B An example is shown where the angle is set from 0 degrees to 360 degrees in steps of 11.25 degrees. Quantization was performed, and some angles that were close to the vertical direction were removed, resulting in a total of 24 angles.

[0049] Figure 6 A flowchart illustrating an exemplary prediction for video encoding according to an embodiment of the present invention is shown, wherein additional assumptions for prediction are disabled for small chroma blocks.

[0050] Figure 7 A flowchart illustrating an exemplary prediction for video decoding according to an embodiment of the present invention is shown, wherein additional assumptions for prediction are disabled for small chroma blocks. Detailed Implementation

[0051] The following description represents the preferred mode of carrying out the invention. This description is intended to illustrate the general principles of the invention and should not be considered limiting. The scope of the invention is best determined by referring to the appended claims.

[0052] To improve encoding / decoding efficiency, a multiple hypothesis (MH) prediction mode is disclosed. When the current block uses the MH prediction mode, additional prediction hypotheses are combined with existing prediction hypotheses through weighted averaging, and the combined prediction is the final prediction for the current block. To overcome the processing efficiency problem associated with small blocks, a simplified method for the MH prediction mode is disclosed, wherein, according to the present invention, the MH prediction mode is not applied to chroma blocks under certain conditions. When the MH prediction mode is not applied to chroma blocks, this means that the additional prediction hypotheses are not combined with the existing prediction hypotheses of the chroma block, and the existing prediction hypotheses are used as the final prediction for the current chroma block. When the MH prediction mode is applied to chroma blocks, this means that the additional prediction hypotheses are combined with the existing prediction hypotheses, and the combined prediction is used as the final prediction for the current chroma block. The proposed method is applied when enabled and predetermined conditions are met.

[0053] In one embodiment, the MH prediction model can be CIIP, TPM, or GEO.

[0054] In another embodiment, the proposed method can be applied even if the original flags (e.g., CIIP, TPM, or GEO) of the MH mode at the CU level are true. For example, the MH mode is not applied to the chroma block even if the CU-level CIIP flag is true. This means that the final prediction for the luma block is a combined prediction, formed by existing prediction assumptions and additional prediction assumptions; for the chroma block, the final prediction is the existing prediction.

[0055] Current VVC supports flexible partitioning mechanisms including QT, BT, and TT. In this partitioning structure, the block size can range from 128 to 4 for the luma component and from 64 to 2 for the chroma component. The introduction of small block sizes (i.e., 2xN) leads to inefficient hardware implementations. This results in pipeline latency and requires the processing of 2xN pixels in the hardware architecture. In most hardware implementations, 4x1 pixels are used for luma and chroma per CPU (or GPU) clock cycle. However, it can be asserted that for 2xN blocks, an additional 2x2 pixels are required per clock cycle. Furthermore, 2xN memory accesses (reads and writes) are inefficient because only 2x1 pixels are fetched per access. Intra-frame blocks have more dependencies than inter-frame blocks. The 2xN intra-frame block is of greatest concern. In the dual-tree case, the minimum luma size was set to 4x4.2xN, a constraint that has been deprecated. However, some 2xN intra-chroma blocks still exist in the single-tree case (e.g., 2xN intra-chroma blocks for CIIP). To address this issue, in another embodiment, "MH mode is not applied to chroma blocks" means that other prediction assumptions are not combined with the original (existing) prediction assumptions of the chroma block. In the case of CIIP, "MH mode is not applied to chroma blocks" means that for chroma blocks, intra-prediction is not combined with inter-prediction, and thus inter-prediction is used directly.

[0056] In another embodiment, the proposed method is enabled for chroma format 4:4:4.

[0057] In another embodiment, the proposed method is enabled for chroma format 4:2:0.

[0058] In another embodiment, the proposed method is enabled for chroma format 4:2:2.

[0059] In another embodiment, the proposed method is enabled for chroma format 4:2:1.

[0060] In another embodiment, the proposed method is enabled for chroma format 4:1:1.

[0061] In another embodiment, the proposed method is enabled for chroma format 4:0:0 (i.e., monochromatic).

[0062] In another embodiment, the predefined conditions are based on the width, height, or area of ​​the block.

[0063] In one sub-implementation, a "block" can be either a luma block or a chroma block. When the block represents a chroma block, the corresponding block width or height depends on the chroma format used. For example, if the chroma format used is 4:2:0, the corresponding block width is configured to be half the width of the juxtaposed luma block.

[0064] In one sub-implementation, the predetermined conditions are that the block width is less than threshold 1 and / or the block height is less than threshold 2. For example, when the CIIP flag is enabled and the corresponding chroma block's block width is less than 4, the proposed method is used (MH prediction mode is not applied to the chroma block). The chroma block can be a chroma block of Cb or Cr composition.

[0065] In another sub-implementation, the predefined conditions are that the block width is greater than threshold 1 and / or the block height is greater than threshold 2.

[0066] In another sub-implementation, the predefined condition is that the block area is less than a threshold of 3.

[0067] In another sub-implementation, the predefined condition is that the block area is greater than a threshold of 3.

[0068] In another embodiment, the threshold 1 can be a positive integer, such as 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, or 1024.

[0069] In another embodiment, the threshold 1 can be a variable defined in TU (or TB), CU (or CB), CTU (or CTB), slice, tile, tile group, SPS, PPS, or picture level. The variable can be 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, or 1024.

[0070] In another embodiment, the threshold 2 can be a positive integer, such as 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, or 1024.

[0071] In another embodiment, the threshold 2 can be a variable defined in TU (or TB), CU (or CB), CTU (or CTB), slice, tile, tile group, SPS, PPS, or picture level. The variable can be 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, or 1024.

[0072] In another embodiment, the threshold 3 can be a positive integer, such as 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, or 1024.

[0073] In another embodiment, the threshold 3 can be a variable defined in TU (or TB), CU (or CB), CTU (or CTB), slice, tile, tile group, SPS, PPS, or picture level. The variable can be 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, or 1024.

[0074] In another sub-implementation, threshold 1 and threshold 2 can be the same.

[0075] In another sub-implementation, threshold 1, threshold 2, and / or threshold 3 may be different for different chroma formats.

[0076] In another embodiment, the “block” in this invention may be CU, CB, TU or TB.

[0077] In another embodiment, the proposed method is enabled by an explicit flag of TU (or TB), CU (or CB), CTU (or CTB), stripe, tile, tile group, SPS, PPS, or picture level.

[0078] In another embodiment, the proposed method can be used for lumen blocks, i.e., under certain conditions, the multiple hypothesis (MH) prediction mode is not applied to the lumen blocks. The proposed method is applied when it is enabled and predetermined conditions are met.

[0079] Any combination of the above methods can be applied. For example, when using a chroma format of 4:4:4 and the chroma block width or height is less than 4, MH mode will not be applied to chroma. As another example, when using a chroma format of 4:2:0 and the chroma block width (depending on the chroma format used) is less than 4, MH mode will not be applied to chroma. In other words, when other enabling conditions for MH mode are met (e.g., assuming MH mode is CIIP, then the CIIP flag is enabled), and the chroma block width (depending on the chroma format used) is greater than or equal to 4, then MH mode applies not only to luma blocks but also to chroma blocks.

[0080] Any of the proposed methods described above can be implemented in the encoder and / or decoder. For example, any of the proposed methods can be implemented in the intra / inter-frame coding module and motion compensation module of the encoder, or in the merge candidate derivation module of the decoder. Alternatively, any of the proposed methods can be implemented as circuitry coupled to the intra / inter-frame coding module and / or motion compensation module of the encoder, or the merge candidate derivation module of the decoder.

[0081] Figure 6A flowchart illustrating an exemplary prediction for video encoding according to an embodiment of the present invention is shown, wherein additional assumptions for prediction are disabled for small chroma blocks (existing predictions are used as the final prediction for the small chroma blocks). The steps shown in the flowchart, and other subsequent flowcharts in this disclosure, can be implemented as program code executable on one or more processors (e.g., one or more CPUs) on the encoder side and / or decoder side. The steps shown in the flowchart can also be implemented in hardware, such as one or more electronic devices or processors arranged to perform the steps in the flowchart. According to the method, in step 610, a current block comprising a luma block and one or more chroma blocks is received, wherein the current block is generated by partitioning an image region into one or more partition blocks including the current block using a single partition tree. The current block is allowed to use one or more encoding / decoding tools containing multi-hypothesis prediction modes. The single partition tree is a single tree for luma and chroma. In step 620, a target encoding / decoding mode for the current block is determined. In step 630, the current block is encoded according to the target encoding / decoding mode, wherein if the target encoding / decoding mode corresponds to a multi-hypothesis prediction mode and the width, height, or area of ​​the one or more chroma blocks is less than a threshold, then additional hypotheses for the prediction of the one or more chroma blocks are disabled.

[0082] Figure 7 A flowchart illustrating an exemplary prediction for video decoding according to an embodiment of the present invention is shown, wherein additional assumptions for prediction are disabled for small chroma blocks (existing predictions are used as the final prediction for the small chroma blocks). According to the method, in step 710, compressed data including the current block is received, wherein the current block comprises a luma block and one or more chroma blocks, and more partition blocks including the current block are generated by dividing the image region into one or more using a single partition tree. One or more encoding tools including a multi-hypothesis prediction mode are allowed for the current block. The single partition tree is a single tree for luma and chroma. In step 720, a target codec mode for the current block is determined. In step 730, the current block is decoded according to the target codec mode, wherein if the target codec mode corresponds to a multi-hypothesis prediction mode, and the width, height, or area of ​​the one or more chroma blocks is less than a threshold, then additional assumptions for the prediction of the one or more chroma blocks are disabled.

[0083] The flowchart shown is intended to illustrate an example of video encoding and decoding according to the present invention. Those skilled in the art can modify each step, rearrange the steps, split the steps, or combine the steps to practice the invention without departing from its spirit. In this disclosure, specific syntax and semantics have been used to illustrate examples for implementing embodiments of the invention. Those skilled in the art can practice the invention by substituting equivalent syntax and semantics without departing from its spirit.

[0084] The above description is presented to enable those skilled in the art to practice the invention provided in the context of a particular application and its requirements. Various modifications to the described embodiments will be apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments. Therefore, the invention is not intended to be limited to the specific embodiments shown and described, but is consistent with the broadest scope consistent with the principles and novel features disclosed herein. In the above detailed description, various specific details are shown to provide a thorough understanding of the invention. However, those skilled in the art will understand that the invention can be practiced.

[0085] The embodiments of the present invention described above can be implemented in various hardware, software code, or a combination of both. For example, embodiments of the present invention may be one or more circuits integrated into a video compression chip, or program code integrated into video compression software to perform the processes described herein. Embodiments of the present invention may also be program code to be executed on a digital signal processor (DSP) to perform the processes described herein. The present invention may also include numerous functions executed by a computer processor, digital signal processor, microprocessor, or field-programmable gate array (FPGA). These processors may be configured to perform specific tasks according to the present invention by executing machine-readable software code or firmware code that defines the specific methods embodied in the present invention. The software code or firmware code may be developed in different programming languages ​​and in different formats or styles. The software code may also be compiled for different target platforms. However, different code formats, software code styles and languages, and other means of configuring the code to perform the tasks according to the present invention will not depart from the spirit and scope of the present invention.

[0086] The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The described examples should be considered illustrative rather than restrictive in all respects. Therefore, the scope of the invention is indicated by the appended claims rather than the foregoing description. All modifications falling within the equivalent meaning and scope of the claims should be included within its scope.

Claims

1. A video encoding method, the method comprising: The current block is received, comprising a luminance block and one or more chrominance blocks, wherein the current block is generated by dividing an image region into one or more partition blocks including the current block using a single partition tree, and the current block allows the use of an encoding tool that includes one or more encoding / decoding tools that include a multi-hypothesis prediction mode, which incorporates existing prediction hypotheses when applied. Determine the target encoding / decoding mode for the current block, which, when applied, includes combining existing prediction hypotheses from the multi-hypothesis prediction mode with additional prediction hypotheses, wherein the additional prediction hypotheses differ from the existing prediction hypotheses in the multi-hypothesis prediction mode; and The current block is encoded according to the target codec mode, wherein if the target codec mode corresponds to a multi-hypothesis prediction mode and the width, height or area of ​​the one or more chroma blocks is less than a threshold, the additional hypothesis prediction in the target codec mode for the one or more chroma blocks is disabled, and the existing prediction hypothesis in the multi-hypothesis prediction mode is used as the final prediction for the one or more chroma blocks.

2. The method according to claim 1, characterized in that, The additional assumption of the prediction is intra-frame prediction, and intra-frame prediction for the one or more chroma blocks is disabled if the width of the one or more chroma blocks is less than a threshold of 4.

3. The method according to claim 1, characterized in that, The multi-hypothesis prediction mode corresponds to the inter-frame / intra-frame combined prediction (CIIP) mode.

4. The method according to claim 1, characterized in that, The multi-hypothesis prediction model corresponds to the triangular prediction model (TPM).

5. The method according to claim 1, characterized in that, The multi-hypothesis prediction model corresponds to the geometric merging model (GEO).

6. The method according to claim 1, characterized in that, The current block is in chroma format 4:4:4, 4:2:2, or 4:2:

0.

7. The method according to claim 1, characterized in that, The threshold is transmitted in the video bitstream at the transform unit (TU) or transform block (TB), coding unit (CU) or coding block (CB), coding tree unit (CTU) or coding tree block (CTB), slice, tile, tile group, sequence parameter set (SPS), picture parameter set (PPS), or picture level signal transmission.

8. The method according to claim 1, characterized in that, The image region corresponds to a coding tree unit (CTU).

9. A video encoding apparatus, the apparatus comprising one or more electronic circuits or processors for: Receive the current block, which includes one luminance block and one or more chrominance blocks, wherein... An image region is divided into one or more partition blocks, including the current block, by using a single partition tree. The current block allows the use of one or more encoding and decoding tools, including a multi-hypothesis prediction mode, which incorporates existing prediction hypotheses when applied. Determine the target encoding / decoding mode for the current block. When applied, the target encoding / decoding mode includes a combination of existing prediction hypotheses and additional prediction hypotheses in the multi-hypothesis prediction mode. The additional prediction hypotheses are different from the existing prediction hypotheses in the multi-hypothesis prediction mode. and The current block is encoded according to the target codec mode, wherein if the width, height or area of ​​the one or more chroma blocks is less than a threshold and the target codec mode corresponds to a multi-hypothesis prediction mode, then the additional hypothesis prediction in the target codec mode for the one or more chroma blocks is disabled, and the existing prediction hypothesis in the multi-hypothesis prediction mode is used as the final prediction for the one or more chroma blocks.

10. A method for video decoding, the method comprising: Receive compressed data including the current block, wherein the current block includes a luma block and one or more chroma blocks, generate the current block by dividing an image region into one or more partition blocks including the current block using a single partition tree, and the current block allows one or more encoding / decoding tools to include a multi-hypothesis prediction mode, which includes existing prediction hypotheses when applied; Determine the target encoding / decoding mode for the current block. When applied, the target encoding / decoding mode includes a combination of existing prediction hypotheses and additional prediction hypotheses in the multi-hypothesis prediction mode. The additional prediction hypotheses are different from the existing prediction hypotheses in the multi-hypothesis prediction mode. and The current block is decoded according to the target codec mode, wherein if the target codec mode corresponds to a multi-hypothesis prediction mode and the width, height or area of ​​the one or more chroma blocks is less than a threshold, then the additional hypothesis prediction in the target codec mode for the one or more chroma blocks is disabled, and the existing prediction hypothesis in the multi-hypothesis prediction mode is used as the final prediction for the one or more chroma blocks.

11. The method according to claim 10, characterized in that, The additional assumption of the prediction is intra-frame prediction, and intra-frame prediction for the one or more chroma blocks is disabled if the width of the one or more chroma blocks is less than a threshold of 4.

12. The method according to claim 10, characterized in that, The multi-hypothesis prediction mode corresponds to the combined inter-frame / intra-frame prediction (CIIP) mode.

13. The method according to claim 10, characterized in that, The multi-hypothesis prediction model corresponds to the triangular prediction model (TPM).

14. The method according to claim 10, characterized in that, The multi-hypothesis prediction model corresponds to the geometric merging model (GEO).

15. The method according to claim 10, characterized in that, The current block is in chroma format 4:4:4, 4:2:2, or 4:2:

0.

16. The method according to claim 10, characterized in that... The threshold is used for parsing at the transform unit (TU) or transform block (TB), coding unit (CU) or coding block (CB), coding tree unit (CTU) or coding tree block (CTB), slice, tile, tile group, sequence parameter set (SPS), picture parameter set (PPS), or picture level of the video bitstream.

17. The method according to claim 10, characterized in that, The image region corresponds to a coding tree unit (CTU).

18. A video decoding apparatus, the apparatus comprising one or more electronic circuits or processors arranged to: receive compressed data including a current block, wherein the current block includes a luma block and one or more chroma blocks; generate the current block by dividing an image region into one or more partition blocks including the current block using a single partition tree; and allow the current block to allow one or more encoding / decoding tools including a multi-hypothesis prediction mode, the multi-hypothesis prediction mode incorporating existing prediction hypotheses when applied. Determine the target encoding / decoding mode for the current block. When applied, the target encoding / decoding mode includes a combination of existing prediction hypotheses and additional prediction hypotheses in the multi-hypothesis prediction mode. The additional prediction hypotheses are different from the existing prediction hypotheses in the multi-hypothesis prediction mode. as well as The current block is decoded according to the target codec mode, wherein if the target codec mode corresponds to a multi-hypothesis prediction mode and the width, height or area of ​​the one or more chroma blocks is less than a threshold, the additional hypothesis prediction in the target codec mode for the one or more chroma blocks is disabled, and the existing prediction hypothesis in the multi-hypothesis prediction mode is used as the final prediction for the one or more chroma blocks.

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