BR112021017512B1 - VIDEO PROCESSING METHOD, VIDEO DATA PROCESSING APPARATUS AND COMPUTER-READABLE NON-TRANSITORY STORAGE AND RECORDING MEDIA - Google Patents

Abstract

ENHANCED WEIGHTING PROCESSING OF COMBINED INTRA- AND INTER-PREDICTION. The present application relates to enhanced weighting processing of combined intra- and inter-prediction. A method for video processing includes: determining, during a conversion between a current video block, which is encoded in a combined intra- and inter-prediction (CIIP) mode, of a video and a bitstream representation of the current video block, a pair of weights comprising a first weight for a first prediction result of the current video block and a second weight for a second prediction result of the current video block, based on one or more video blocks neighboring the current video block, wherein the first prediction result is generated by an intra-prediction mode and the second prediction result is generated by an inter-prediction mode; and determining a prediction result of the current block based on a weighted sum of the first prediction result and the second prediction result.

Description

CROSS-REFERENCE TO RELATED ORDERS

[001] This application is a national phase of International Patent Application No. PCT/CN2020/080632, filed on March 23, 2020, which claims the priority and benefits of International Patent Application No. PCT/CN2019/079148, filed on March 21, 2019, and International Patent Application No. PCT/CN2019/100616, filed on August 14, 2019. All disclosures of International Patent Application No. PCT/CN2019/079148 and International Patent Application No. PCT/CN2019/100616 are incorporated by reference as part of the disclosure of this application.

TECHNICAL FIELD

[002] This document is related to video and image encoding and decoding technologies, and the word “encoding” can be understood either as the reverse step to the decoding step, or as the set of these steps, thus encompassing the meanings of encoding itself and decoding.

BACKGROUND

[003] Digital video accounts for the largest use of bandwidth on the Internet and other digital communications networks. As the number of connected user devices capable of receiving and displaying video increases, bandwidth demand for digital video use is expected to continue to grow.

SUMMARY

[004] The disclosed techniques may be used by video or image decoder or encoder embodiments for which combined intra- and inter-prediction is used.

[005] In an exemplary aspect, a video processing method is disclosed. The method includes determining a coded mode of a first video block; constraining one or more flags to an operational state based on the determination of the coded mode of the first video block, the operational state being false or true; and performing further processing of a second video block according to the operational state of the one or more flags, wherein the first video block is a neighboring video block or a reference video block relative to the second video block.

[006] In another example aspect, a video processing method includes determining whether pairwise prediction or bicombined prediction is used with respect to a first video block; determining a combined intra- and inter-prediction (CIIP) operational state based on the determination that pairwise prediction or bicombined prediction is used, wherein the operational state is enabled or disabled; and performing further processing of the first video block in accordance with the CIIP operational state.

[007] In another exemplary aspect, another video processing method is disclosed. The method includes performing a conversion between a video block of a video and an encoded representation of the video block using a combined intra- and inter-prediction mode wherein the encoded representation corresponds to a weighted average of intra- and inter-prediction results of the video block using a weight pair from a set of weight pairs in which less than three pairs are included.

[008] In another exemplary aspect, another video processing method is disclosed. The method includes performing a conversion between a video block of a video and an encoded representation of the video block using a combined intra- and inter-prediction mode wherein the encoded representation corresponds to a weighted average of intra- and inter-prediction results of the video block using a weight pair from a set of weight pairs determined due to the encoding information of one or more neighboring blocks.

[009] In another exemplary aspect, another video processing method is disclosed. The method includes determining, during a conversion between a first block in video data and a bitstream representation of the first block, one or more coded modes of one or more second blocks; determining, based on the one or more coded modes of one or more second blocks, a coded mode constraint of the first block; and performing, at least by applying the coded mode constraint of the first block, the conversion; wherein the one or more second blocks comprise at least one of an adjacent block, a non-adjacent block, and a reference block of the first block.

[010] In another exemplary aspect, another video processing method is disclosed. The method includes performing a conversion between a current block in video data and a bitstream representation of the current block using at least one of a combined intra- and inter-prediction (CIIP), a diffusion filtering, a bilateral filtering, a transform domain filtering, or another type of post-reconstruction filtering that is different from diffusion filtering, bilateral filtering, and transform domain filtering, wherein reconstructed neighboring samples of the current block used in at least one of the combined inter- and intra-prediction (CIIP), the diffusion filtering, the bilateral filtering, the transform domain filtering, or the other type of post-reconstruction filtering are replaced by approximated samples generated from the corresponding samples of the reconstructed neighboring samples in one or more reference pictures.

[011] In another exemplary aspect, another video processing method is disclosed. The method includes storing a combined intra-interprediction (CIIP) and/or intra-mode CIIP mode flag with motion information in a history-based motion vector prediction (HMVP) table; and performing, at least based on the HMVP table, a conversion between a current block in video data and a bitstream representation of the current block.

[012] In another exemplary aspect, another video processing method is disclosed. The method includes determining, during a conversion between a current block in video data and a bitstream representation of the current block, a prediction mode for the current block; determining the applicability of a combined intra- and inter-prediction (CIIP) mode by indicating that the CIIP mode is enabled for the current block in response to determining that the current block is encoded with an advanced motion vector prediction (AMVP) mode or a blending mode; and performing, based on the applicability of the CIIP mode, the conversion.

[013] In another exemplary aspect, another video processing method is disclosed. The method includes determining, during a conversion between a current block in video data and a bitstream representation of the current block, a type of a selected blend candidate for the current block and determining the applicability of combined intra and inter prediction (CIIP) for the current block according to the selected blend candidate type, wherein the current block is encoded in blend mode.

[014] In another exemplary aspect, another video processing method is disclosed. The method includes encoding, during a conversion between a current video block in video data and a bitstream representation of the current video block, a combined intra- and inter-prediction (CIIP) flag for the current video block by a context-based coding model without reference to a CIIP flag of one or more video blocks neighboring the current video block, and performing, at least by applying the combined intra- and inter-prediction (CIIP) flag of the current video block, the conversion.

[015] In another exemplary aspect, another video processing method is disclosed. The method includes encoding, during a conversion between a current video block in video data and a bitstream representation of the current video block, a combined intra- and inter-prediction (CIIP) flag for the current video block by a bias encoding and performing, at least by applying the combined intra- and inter-prediction (CIIP) flag, the conversion.

[016] In another exemplary aspect, another video processing method is disclosed. The method includes determining an intraprediction mode of a first video block of a video according to a rule, and the rule comprises: skipping, during an intraprediction mode derivation process of the first video block, checking the combined intra and intraprediction (CIIP) flag of one or more video blocks neighboring the first video block, and performing, based on the at least one determined intraprediction mode, a conversion between the first video block and a bitstream representation of the first video block.

[017] In another exemplary aspect, another video processing method is disclosed. The method includes determining, during a conversion between a current video block, which is encoded in a combined intra- and inter-prediction (CIIP) mode, of a video and a bitstream representation of the current video block, a pair of weights comprising a first weighting for a first prediction result of the current video block and a second weighting for a second prediction result of the current video block, based on one or more video blocks neighboring the current video block, wherein the first prediction result is generated by an intra-prediction mode and the second prediction result is generated by an inter-prediction mode; and determining a prediction result of the current block based on a weighted sum of the first prediction result and the second prediction result.

[018] In another exemplary aspect, the method described above may be implemented by a video encoding apparatus comprising a processor.

[019] In yet another example aspect, these methods may be embodied in the form of processor-executable instructions and stored on a computer-readable program medium.

[020] These and other aspects are further described in this document.

BRIEF DESCRIPTION OF THE DRAWINGS

[021] FIG. 1 shows an example of a derivation process for constructing a list of merge candidates.

[022] FIG. 2 shows an example of spatial merge candidate positions.

[023] FIG. 3 shows an example of candidate pairs considered for checking for redundancy of spatial merge candidates.

[024] FIG. 4 shows an example of positions for second PU of Nx2N and partitions of 2NxN.

[025] FIG. 5 shows an example of motion vector scaling for temporal blending candidate.

[026] FIG. 6 shows an example of candidate positions for temporal blending candidate, C0 and C1.

[027] FIG. 7 shows an example of a combined bi-predictive blend candidate.

[028] FIG. 8 shows an example of a derivation process for motion vector prediction candidates.

[029] FIG. 9 shows an example of motion vector scaling for spatial motion vector candidate.

[030] FIG. 10 shows an example of alternative temporal motion vector prediction (ATMVP) for a coding unit (CU).

[031] FIG. 11 shows an example of neighboring samples used to derive IC parameters.

[032] FIG. 12 shows an example of an ultimate motion vector expression (UMVE) search process.

[033] FIG. 13 shows an example of a UMVE search point.

[034] FIG. 14 shows an example of a decoding flowchart with a proposed HMVP method.

[035] FIG. 15 shows an example of table update using the proposed HMVP method.

[036] FIG. 16 shows an example of a symmetric mode.

[037] FIG. 17 shows an example of neighboring samples of a current block and their corresponding samples in the reference image.

[038] FIG. 18 is a block diagram of an example of a video processing apparatus.

[039] FIG. 19 shows a block diagram of an example implementation of a video encoder.

[040] FIG. 20 is a flowchart for an example of a video processing method.

[041] FIG. 21 is a flowchart for an example of a video processing method.

[042] FIG. 22 shows an example of top and left neighbor blocks used in evaluating CIIP weights.

[043] FIG. 23 is a flowchart for an example of a video processing method.

[044] FIG. 24 is a flowchart for an example of a video processing method.

[045] FIG. 25 is a flowchart for an example of a video processing method.

[046] FIG. 26 is a flowchart for an example of a video processing method.

[047] FIG. 27 is a flowchart for an example of a video processing method.

[048] FIG. 28 is a flowchart for an example of a video processing method.

[049] FIG. 29 is a flowchart for an example of a video processing method.

[050] FIG. 30 is a flowchart for an example of a video processing method.

[051] FIG. 31 is a flowchart for an example of a video processing method.

DETAILED DESCRIPTION

[052] The present document provides several techniques that can be used by a video or image bitstream decoder to improve the quality of decompressed or decoded digital images or video. For brevity, the term “video” is used in the present invention to include both a sequence of images (traditionally called video) and individual images. Furthermore, a video encoder can also implement these techniques during the encoding process in order to reconstruct the decoded frames used for further encoding.

[053] Section headings are used herein for ease of understanding and do not limit embodiments and techniques to the corresponding sections. As such, embodiments of one section may be combined with embodiments of other sections.

1. Summary

[054] This document relates to video coding technologies. Specifically, it relates to combined intra and inter prediction (CIIP) in video encoding or decoding. It may apply to existing video coding standard such as HEVC or to the upcoming Versatile Video Coding standard. It may also apply to future video coding or video codec standards.

2. Background

[055] Video coding standards have evolved primarily through the development of the well-known ITU-T and ISO/IEC standards. ITU-T produced H.261 and H.263, ISO/IEC produced MPEG-1 and MPEG-4 Visual, and the two organizations jointly produced the H.262/MPEG-2 Video and H.264/MPEG-4 Advanced Video Coding (AVC) and H.265/HEVC standards [1]. Since H.262, video coding standards have been based on the hybrid video coding framework in which temporal prediction plus transform coding are used. To explore future video coding technologies beyond HEVC, the Joint Video Exploration Team (JVET) was jointly founded by VCEG and MPEG in 2015. Since then, many new methods have been adopted by JVET and put into the reference software called the Joint Exploration Model (JEM). In April 2018, the Joint Video Expert Team (JVET) between VCEG (Q6/16) and ISO/IEC JTC1 SC29/WG11 (MPEG) was established to work on the VVC standard targeting a 50% bitrate reduction compared to HEVC.

[056] FIG. 19 is a block diagram of an example implementation of a video encoder. Fig. 19 shows that the encoder implementation has an embedded feedback path in which the video encoder also performs video decoding functionality (reconstructing the compressed representation of video data for use in encoding the next video data). 2.1 Interprediction in HEVC/H.265

[057] Each inter-predicted PU has motion parameters for one or two reference image lists. The motion parameters include a motion vector and a reference image index. The use of one of the two reference image lists can also be flagged using inter_pred_idc. Motion vectors can be explicitly encoded as deltas with respect to the predictors.

[058] When a CU is coded with the skip mode, a PU is associated with the CU and there are no significant residual coefficients, no encoded motion vector delta or reference picture index. A blending mode is specified whereby motion parameters for the current PU are obtained from neighboring PUs, including spatial and temporal candidates. The blending mode can be applied to any interpredicted PU, not just for the skip mode. The alternative to the blending mode is the explicit transmission of motion parameters, where the motion vector (to be more precise, motion vector difference (MVD) compared to a motion vector predictor), corresponding reference picture index for each reference picture list, and use of the reference picture list are explicitly signaled by each PU. Such a mode is referred to as Advanced Motion Vector Prediction (AMVP) in this disclosure.

[059] When the flag indicates that one of the two reference image lists should be used, the PU is produced from a block of samples. This is referred to as “uniprediction”. Uniprediction is available for both P-slices and B-slices.

[060] When the flag indicates that both reference image lists should be used, the PU is produced from two blocks of samples. This is referred to as “biprediction”. Biprediction is only available for B slices.

[061] The following text provides details about the interpretation modes specified in HEVC. The description will begin with the blending mode. 2.1.1 Blending Mode 2.1.1.1 Derivation of Blending Mode Candidates

[062] When a PU is predicted using the blending mode, an index pointing to an entry in the blending candidate list is parsed from the bitstream and used to retrieve the motion information. The construction of this list is specified in the HEVC standard and can be summarized according to the following sequence of steps: Step 1: Derivation of initial candidates Step 1.1: Derivation of spatial candidates Step 1.2: Redundancy check for spatial candidates Step 1.3: Derivation of temporal candidates Step 2: Insertion of additional candidates Step 2.1: Creation of bi-predictive candidates Step 2.2: Insertion of zero-motion candidates

[063] These steps are also schematically depicted in Figure 1. For spatial merge candidate derivation, a maximum of four merge candidates are selected from candidates that are located at five different positions. For temporal merge candidate derivation, a maximum of one merge candidate is selected from two candidates. Since constant number of candidates for each PU is assumed in the decoder, additional candidates are generated when the number of candidates obtained from step 1 does not reach the maximum number of merge candidates (MaxNumMergeCand) that is signaled in the slice header. Since the number of candidates is constant, the best merge candidate index is encoded using truncated unary (TU) binarization. If the CU size is equal to 8, all PUs of the current CU share a single merge candidate list, which is identical to the merge candidate list of the 2Nx2N prediction unit.

[064] The operations associated with the mentioned steps are detailed below. 2.1.1.2 Derivation of spatial candidates

[065] In deriving spatial merge candidates, a maximum of four merge candidates are selected from the candidates located at the positions depicted in Fig. 22. The order of derivation is A1, B1, B0, A0, and B2. Position B2 is considered only when any PU of position A1, B1, B0, A0, and B2 is not available (e.g., because it belongs to another slice or tile) or is intra-coded. After the candidate at position A1 is added, the addition of the remaining candidates is subject to a redundancy check that ensures that candidates with the same motion information are excluded from the list so that coding efficiency is improved. To reduce computational complexity, not all possible candidate pairs are considered in the aforementioned redundancy check. Instead, only the pairs connected by an arrow in FIG. 3 are considered, and a candidate is only added to the list if the corresponding candidate used for redundancy check does not have the same motion information. Another source of duplicated motion information is the “second PU” associated with different partitions of 2Nx2N. As an example, Fig. 4 depicts the second PU for the case of Nx2N and 2NxN, respectively. When the current PU is partitioned as Nx2N, the candidate at position A1 is not considered for list construction. In fact, adding this candidate will lead to two prediction units having the same motion information, which is redundant to having only one PU in a coding unit. Similarly, position B1 is not considered when the current PU is partitioned as 2NxN. 2.1.1.3 Temporal Candidate Derivation

[066] In this step, only one candidate is added to the list. Particularly, in deriving this temporal blending candidate, a scaled motion vector is derived based on the co-located PU belonging to the picture that has the smallest POC difference with the current picture within the given reference picture list. The list of reference pictures to be used for deriving the co-located PU is explicitly signaled in the slice header. The scaled motion vector for a blending candidate is obtained as illustrated by the dotted line in Figure 5, which is scaled from the motion vector of the co-located PU using the POC distances, tb and td, where tb is defined to be the POC difference between the reference picture of the current picture and the current picture and td is defined as the POC difference between the reference picture of the co-located picture and the co-located picture. The reference picture index of a temporal blending candidate is set to zero. A practical realization of the scaling process is described in the HEVC specification. For a slice B, two motion vectors, one is for reference image list 0 and the other is for reference image list 1, are obtained and combined to make the bi-predictive blend candidate.

[067] In the co-located PU(Y) belonging to the reference frame, the position for the temporal candidate is selected between candidates C0 and C1, as depicted in Figure 6. If PU at position C0 is not available, is intracoded, or is outside the current CTU line, position C1 is used. Otherwise, position C0 is used in deriving the temporal blend candidate. 2.1.1.4 Inserting Additional Candidates

[068] In addition to spatial and temporal blend candidates, there are two additional types of blend candidates: combined bi-predictive blend candidate and zero-blend candidate. Combined bi-predictive blend candidates are generated by using both spatial and temporal blend candidates. A combined bi-predictive blend candidate is used only for Slice B. Combined bi-predictive candidates are generated by combining the motion parameters of the first list of reference images of one initial candidate with the motion parameters of the second list of reference images of another. If these two tuples provide different motion hypotheses, they form a new bi-predictive candidate. As an example, Figure 7 depicts the case when two candidates in the original list (left), which have either mvL0 and refIdxL0 or mvL1 and refIdxL1, are used to create a combined bi-predictive blend candidate that is added to the final list (right). There are a number of rules regarding the combinations that are considered to generate these additional blend candidates.

[069] Zero-motion candidates are inserted to fill the remaining entries in the merge candidate list and thus achieve the MaxNumMergeCand capacity. These candidates have zero spatial offset and a reference image index that starts from zero and increases every time a new zero-motion candidate is added to the list. The number of reference frames used by these candidates is one and two for unidirectional and bidirectional prediction, respectively. Finally, no redundancy checks are performed on these candidates. 2.1.1.5 Motion Estimation Regions for Parallel Processing

[070] To speed up the encoding process, motion estimation can be performed in parallel, where motion vectors for all prediction units within a given region are derived simultaneously. Deriving merge candidates from the spatial neighborhood can interfere with parallel processing because a prediction unit cannot derive motion parameters from an adjacent PU until its associated motion estimation is complete. To mitigate the trade-off between coding efficiency and processing latency, HEVC defines a motion estimation region (MER) whose size is signaled in the prepared image parameter using the “log2_parallel_merge_level_minus2” syntax element. When a MER is defined, merge candidates that fall within the same region are marked as unavailable and are therefore not considered in the list construction. 2.1.2 AMVP

[071] AMVP exploits the spatiotemporal correlation of the motion vector with neighboring PUs, which is used for explicit transmission of motion parameters. For each reference image list, a list of motion vector candidates is constructed by first checking the availability of the left, up, temporally neighboring PU positions, removing redundant candidates, and adding the zero vector to make the candidate list constant length. Then, the encoder can select the best predictor from the candidate list and transmit the corresponding index indicating the chosen candidate. Similar to the merge index signaling, the index of the best motion vector candidate is encoded using truncated unary. The maximum value to be encoded in this case is 2 (see Figure 8). In the following sections, details about the derivation process of the motion vector prediction candidate are provided. 2.1.2.1 AMVP Candidate Derivation

[072] Figure 8 summarizes the derivation process for the candidate motion vector prediction.

[073] In motion vector prediction, two types of motion vector candidates are considered: spatial motion vector candidate and temporal motion vector candidate. For spatial motion vector candidate derivation, two motion vector candidates are eventually derived based on motion vectors of each PU located at five different positions, as depicted in Figure 2.

[074] For temporal motion vector candidate derivation, a motion vector candidate is selected from two candidates, which are derived based on two different co-located positions. After the first list of spatiotemporal candidates is made, duplicate motion vector candidates in the list are removed. If the number of potential candidates is greater than two, motion vector candidates whose reference image index in the associated reference image list is greater than 1 are removed from the list. If the number of spatiotemporal motion vector candidates is less than two, additional zero motion vector candidates are added to the list. 2.1.2.2 Spatial Motion Vector Candidates

[075] In deriving spatial motion vector candidates, a maximum of two candidates are considered among five potential candidates, which are derived from PUs located at positions as depicted in Figure 2, these positions being the same as those of the motion blend. The derivation order for the left side of the current PU is defined as A0, A1, and scaled A0, scaled A1. The derivation order for the side above the current PU is defined as B0, B1, B2, scaled B B0, scaled B1, scaled B2. For each side, there are therefore four cases that can be used as motion vector candidates, with two cases where no spatial scaling is required and two cases where spatial scaling is used. The four different cases are summarized as follows. No spatial scaling (1) Same reference image list and same reference image index (same POC) (2) Different reference image list but same reference image (same POC) Spatial scaling (3) Same reference image list but different reference images (different POC) (4) Different reference image list and different reference images (different POC)

[076] Non-spatial scaling cases are checked first, followed by spatial scaling. Spatial scaling is considered when the POC is different between the reference image of the neighboring PU and that of the current PU, regardless of the list of reference images. If all the left candidate PUs are not available or are internally coded, scaling for the above motion vector is allowed to aid in the parallel derivation of the left and above MV candidates. Otherwise, spatial scaling is not allowed for the above motion vector.

[077] In a spatial scaling process, the motion vector of the neighboring PU is scaled in a manner similar to temporal scaling, as depicted in Figure 9. The main difference is that the reference image list and the current PU index are given as input; the actual scaling process is the same as that of temporal scaling. 2.1.2.3 Temporal Motion Vector Candidates

[078] Except for the derivation of the reference image index, all processes for the derivation of temporal blending candidates are the same as those for the derivation of spatial motion vector candidates (see Figure 6). The reference image index is signaled to the decoder. 2.2 New Interprediction Methods 2.2.1 Sub-CU-Based Motion Vector Prediction

[079] In JEM with QTBT, each CU can have at most one set of motion parameters for each prediction direction. Two sub-CU level motion vector prediction methods are considered in the encoder by dividing a large CU into sub-CUs and deriving motion information for all sub-CUs from the large CU. The alternative temporal motion vector prediction (ATMVP) method allows each CU to collect multiple sets of motion information from multiple blocks smaller than the current CU in the co-located reference image. In the spatial-temporal motion vector prediction (STMVP) method, motion vectors of the sub-CUs are derived recursively using the temporal motion vector predictor and spatial neighbor motion vector.

[080] To preserve the most accurate motion field for sub-CU motion prediction, motion compression for reference frames is currently disabled. 2.2.1.1 Alternative Temporal Motion Vector Prediction

[081] In the alternative temporal motion vector prediction (ATMVP) method, the temporal motion vector prediction (TMVP) of motion vectors is modified by collecting multiple sets of motion information (including motion vectors and reference indices) from blocks smaller than the current CU. As shown in Figure 10, the sub-CUs are NxN square blocks (N is prepared as 4 by default).

[082] ATMVP predicts the motion vectors of the sub-CUs within a CU in two steps. The first step is to identify the corresponding block in a reference image with the so-called temporal vector. The reference image is called the motion source image. The second step is to divide the current CU into sub-CUs and obtain the motion vectors as well as the reference indices of each sub-CU from the block corresponding to each sub-CU, as shown in Figure 10.

[083] In the first step, a reference picture and the corresponding block are determined by the motion information of the spatial neighboring blocks of the current CU. To avoid the repetitive scanning process of neighboring blocks, the first merge candidate in the merge candidate list of the current CU is used. The first available motion vector as well as its associated reference index are prepared to be the temporal vector and index for the motion source picture. In this way, in ATMVP, the corresponding block can be identified more accurately, compared to TMVP, where the corresponding block (sometimes called co-located block) is always in a lower right or center position relative to the current CU.

[084] In the second step, a corresponding block of the sub-CU is identified by the temporal vector in the motion source image by adding to the coordinate of the current CU the temporal vector. For each sub-CU, the motion information of its corresponding block (the smallest motion grid covering the central sample) is used to derive the motion information for the sub-CU. After the motion information of a corresponding NxN block is identified, it is converted to the motion vectors and reference indices of the current sub-CU, in the same way as HEVC TMVP, where motion scaling and other procedures apply. For example, the decoder checks whether the low-delay condition (i.e., the POCs of all reference pictures of the current picture are smaller than the POC of the current picture) is met and possibly uses the motion vector MVx (i.e., the motion vector corresponding to the list of reference pictures X) to predict the motion vector MVy (i.e., with X being equal to 0 or 1 and Y being equal to 1-X) for each sub-CU. 2.2.2 Pairwise Average Candidates

[085] Pairwise average candidates are generated by averaging predefined pairs of candidates in the current blend candidate list, and the predefined pairs are defined as {(0, 1), (0, 2), (1, 2), (0, 3), (1, 3), (2, 3)}, where the numbers denote the blend indices for the blend candidate list. Average motion vectors are calculated separately for each reference list. If both motion vectors are available in a list, these two motion vectors are averaged even when they point to different reference images; if only one motion vector is available, use it directly; if no motion vectors are available, keep this list invalid. Pairwise average candidates replace blended candidates in the HEVC standard.

[086] The complexity analysis of the pairwise average candidates is summarized in Table 1. For the worst case of additional computations for the average (the last column in Table 1), 4 additions and 4 shifts are required for each pair (MVx and MVy in L0 and L1), and 4 reference index comparisons are required for each pair (refIdx0 is valid and refIdx1 is valid in L0 and L1). There are 6 pairs, leading to 24 additions, 24 shifts, and 24 reference index comparisons in total. The combined candidates in the HEVC standard use 2 reference index comparisons for each pair (refIdx0 is valid in L0 and refIdx1 is valid in L1), and there are 12 pairs, leading to 24 reference index comparisons in total.

[087] Table 1: Operation analysis for average candidates in pairs 2.2.3 Local lighting compensation

[088] Local Illumination Compensation (LIC) is based on a linear model for illumination changes, using a scaling factor a and an offset b. And it is adaptively enabled or disabled for each intra-mode encoded coding unit (CU).

[089] When LIC is applied to a CU, a least square error method is employed to derive the parameters a and b by using the neighboring samples of the current CU and its corresponding reference samples. More specifically, as illustrated in Figure 11, the sub-sampled neighboring samples (2:1 sub-sampling) of the CU and the corresponding samples (identified by the motion information of the current CU or sub-CU) in the reference image are used. The IC parameters are derived and applied for each prediction direction separately.

[090] When a CU is coded with blend mode, the LIC flag is copied from neighboring blocks, similar to copying motion information in blend mode; otherwise, a LIC flag is signaled to the CU to indicate whether LIC applies or not.

[091] When LIC is enabled for an image, an additional CU-level RD check is required to determine whether or not LIC is applied for a CU. When LIC is enabled for a CU, mean-removed sum of absolute differences (MR-SAD) and Hadamard-transformed mean-removed sum of absolute differences (MR-SATD) are used, instead of SAD and SATD, for integer pel motion search and fractional pel motion search, respectively.

[092] To reduce the complexity of the encoder, the following encoding scheme is applied in JEM.

[093] LIC is disabled for the entire image when there are no obvious illumination changes between the current image and its reference images. To identify this situation, the histograms of a current image and each reference image of the current image are calculated in the encoder. If the histogram difference between the current image and each reference image of the current image is smaller than a given threshold, LIC is disabled for the current image; otherwise, LIC is enabled for the current image. 2.2.4 Combined Inter- and Intra-Prediction

[094] In some embodiments, multiple hypothesis prediction is proposed, where combined intra- and inter-prediction is a way to generate multiple hypotheses.

[095] When multi-hypothesis prediction is applied to improve intra-mode, multi-hypothesis prediction combines an intra-prediction and a merge-indexed prediction. In a merge CU, a flag is signaled to the merge mode to select an intra-mode from a list of intra-candidates when the flag is true. For the luma component, the list of intra-candidates is derived from 4 intra-prediction modes, including DC, planar, horizontal, and vertical modes, and the size of the intra-candidate list can be 3 or 4 depending on the block shape. When the CU width is greater than twice the CU height, the horizontal mode is exclusive from the intra-mode list, and when the CU height is greater than twice the CU width, the vertical mode is removed from the intra-mode list. An intra-prediction mode selected by the intra-mode index and a merge-indexed prediction selected by the merge index are combined using weighted average. For the chroma component, DM is always applied without extra flags. The weightings for combining the predictions are described below. When DC or planar mode is selected, or the CB width or height is less than 4, equal weightings are applied. For those CBs with CB width and height greater than or equal to 4, when horizontal/vertical mode is selected, a CB is first vertically/horizontally divided into four regions of equal area. Each set of weightings, denoted as (w_intrai, w_interi), where i is from 1 to 4 and (w_intra1, w_inter1) = (6, 2), (w_intra2, w_inter2) = (5, 3), (w_intra3, w_inter3) = (3, 5), and (w_intra4, w_inter4) = (2, 6), will be applied to a corresponding region. (w_intra1, w_inter1) is for the region closest to the reference samples, and (w_intra4, w_inter4) is for the region farthest from the reference samples. Then, the combined prediction can be calculated by summing the two weighted predictions and right-shifting 3 bits. Furthermore, the intraprediction mode for the intrahypothesis of predictors can be saved for reference by the following neighboring CUs.

Generalized biprediction

[096] In conventional biprediction, the L0 and L1 predictors are averaged to generate the final predictor using equal weights 0.5. The predictor generation formula is shown as in Equ. (3) PTraditionalBiPred = (PL0 + PL1 + RoundingOffset) >> shiftNum, (1)

[097] In Equ. (3), PTraditionalBiPred is the final predictor for conventional biprediction, PL0 and PL1 are predictors of L0 and L1, respectively, and RoundingOffset and shiftNum are used to normalize the final predictor.

[098] Generalized biprediction (GBI) is proposed to allow applying different weights to L0 and L1 predictors. The predictor generation is shown in Equ. (4). PGBi = ( (1-w1)* PL0 + w1 * PL1 + RoundingOffsetGBi) >> shiftNumGBi, (2)

[099] In Equ. (4), PGBi is the final GBi predictor. (1-w1) and w1 are the selected GBI weights applied to the L0 and L1 predictors, respectively. RoundingOffsetGBi and shiftNumGBi are used to normalize the final predictor to GBi.

[100] The supported weighting table w1 is {-1/4, 3/8, 1/2, 5/8, 5/4}. One set of equal weights and four sets of unequal weights are supported. For the equal weight case, the process to generate the final predictor is exactly the same as in the conventional biprediction mode. For true biprediction cases under random access (RA) condition, the number of candidate weight sets is reduced to three.

[101] For the advanced motion vector prediction (AMVP) mode, the weight selection in GBI is explicitly signaled at the CU level if this CU is biprediction-encoded. For the blending mode, the weight selection is inherited from the blending candidate. In this proposal, GBI supports DMVR to generate the weighted average of the model as well as the final predictor for BMS-1.0. 2.2.6 Final Motion Vector Expression

[102] In some embodiments, final motion vector expression (UMVE) is presented. UMVE is used to skip or blend mode with a proposed motion vector expression method.

[103] UMVE reuses the merge candidate as used in VVC. Among the merge candidates, a candidate can be selected and is further expanded by the proposed motion vector expression method.

[104] UMVE provides a new motion vector expression with simplified signaling. The expression method includes starting point, motion magnitude, and motion direction.

[105] This proposed technique uses a merge candidate list as is. But only candidates that are of the default merge type (MRG_TYPE_DEFAULT_N) are considered for UMVE expansion.

[106] The candidate base index defines the starting point. The candidate base index indicates the best candidate among the candidates on the list as follows.

[107] Table 1. IDX base candidate

[108] If the base candidate number is equal to 1, the base candidate IDX is not flagged.

[109] The distance index is the information of the movement magnitude. The distance index indicates the predefined distance of the starting point information. The predefined distance is as follows:

[110] Table 2. IDX Distance

[111] The direction index represents the direction of the MVD relative to the starting point. The direction index can represent the four directions as shown below. Table 3. IDX Direction

[112] The UMVE flag is set just after a jump flag and merge flag are sent. If the jump and merge flag are true, the UMVE flag is parsed. If the UMVE flag is equal to 1, the UMVE syntaxes are parsed. But if it is not 1, the AFFINE flag is parsed. If the AFFINE flag is equal to 1, this is AFFINE mode, but if it is not 1, the jump/merge index is parsed for VTM jump/merge mode.

[113] Additional line buffer due to UMVE candidates is not needed. Because a software jump/merge candidate is directly used as a base candidate. Using the input UMVE index, the MV supplement is decided just before motion compensation. There is no need to maintain long line buffer for this. 2.2.7 History-Based Motion Vector Prediction

[114] In our prior invention P1805028401H, one or more lookup tables with at least one move candidate are stored to predict move information of a block.

[115] A history-based MVP (HMVP) method is proposed in which an HMVP candidate is defined as the motion information of a previously coded block. A table with multiple HMVP candidates is maintained during the encoding/decoding process. The table is emptied when a new slice is encountered. Whenever there is an inter-coded block, the associated motion information is added to the last entry of the table as a new HMVP candidate. The overall coding flow is depicted in Figure 13.

[116] In one example, the table size is prepared as L (e.g., L = 16 or 6 or 44), which indicates that up to L HMVP candidates can be added to the table.

[117] In one embodiment, if there are more than L HMVP candidates from the previously encoded blocks, a First-In-First-Out (FIFO) rule is applied such that the table always contains the last L previously encoded move candidates. Figure 14 depicts an example where the FIFO rule is applied to remove an HMVP candidate and add a new one to the table used in the proposed method.

[118] In another embodiment, whenever adding a new motion candidate (such as the current block is intercoded and non-affine mode), a redundancy check process is first applied to identify whether there are identical or similar motion candidates in LUTs. 2.2.8 Symmetric Motion Vector Difference

[119] In some embodiments, symmetric motion vector difference (SMVD) is proposed to encode MVD more efficiently.

[120] First, at the slice level, the variables BiDirPredFlag, RefIdxSymL0, and RefIdxSymL1 are derived as follows:

[121] The forward reference image in reference image list 0, which is closest to the current image, is searched. If found, RefIdxSymL0 is set equal to the reference index of the forward image.

[122] The backward reference image in the reference image list 1 that is closest to the current image is searched for. If found, RefIdxSymL1 is set equal to the reference index of the previous image.

[123] If both forward and backward images are found, BiDirPredFlag is set to 1.

[124] Otherwise, the following applies:

[125] The backward reference image in the reference image list 0 that is closest to the current one is searched for. If found, RefIdxSymL0 is set equal to the reference index of the previous image.

[126] The forward reference image in the reference image list 1 that is closest to the current one is searched for. If found, RefIdxSymL1 is set equal to the reference index of the forward image.

[127] If both the backward and forward images are found, BiDirPredFlag is set to 1. Otherwise, BiDirPredFlag is set to 0.

[128] Second, at the CU level, a symmetric mode flag indicating whether symmetric mode is used or not is explicitly flagged if the prediction direction for the CU is biprediction and BiDirPredFlag is equal to 1.

[129] When the flag is true, only mvp_l0_flag, mvp_l1_flag and MVD0 are explicitly flagged. The reference indices are set equal to RefIdxSymL0, RefIdxSymL1 for list 0 and list 1 respectively. MVD1 is only set equal to -MVD0. The final motion vectors are shown in the formula below.

[130] Modifications to the coding unit syntax are shown in Table 2.

[131] Table 2: Modifications to coding unit syntax 2.2. 9 CIIP in VTM4

[132] In VTM4, when a CU is encoded in blend mode and if the CU contains at least 64 luma samples (i.e., the CU width times the CU height is equal to or greater than 64) then an additional flag is set to indicate whether combined intra- and inter-prediction (CIIP) mode is applied to the current CU.

[133] In order to form the CIIP prediction, an intraprediction mode is first derived from two additional syntax elements. Up to four possible intraprediction modes can be used: DC, planar, horizontal or vertical. Then, the interprediction and intraprediction signals are derived using regular decoding processes. Finally, the weighted average of the intraprediction and interprediction signals is performed to obtain the CIIP prediction.

I. Intraprediction mode derivation

[134] Up to 4 intraprediction modes, including DC, PLANAR, HORIZONTAL and VERTICAL modes, can be used for luma component prediction in CIIP mode. If the CU shape is too wide (i.e. the width is more than twice the height), the HORIZONTAL mode is not allowed. If the CU shape is too narrow (i.e. the height is more than twice the width), the VERTICAL mode is not allowed. In these cases, only 3 intraprediction modes are allowed.

[135] CIIP mode uses 3 most probable modes (MPM) for intraprediction. The CIIP MPM candidate list is formed as follows: - The left and upper neighboring blocks are prepared as A and B, respectively - The intraprediction modes of block A and block B, denoted as intraModeA and intraModeB, respectively, are derived as follows: o Let X be A or B, intraModeX is prepared as DC if 1) block X is not available; or 2) block X is not predicted using CIIP mode or intramode; 3) block B is outside the current CU o otherwise, intraModeX is prepared as 1) DC or PLANAR if the intraprediction mode of block X is DC or PLANAR; or 2) VERTICAL if the intraprediction mode of block X is a “vertical-type” angular mode (greater than 34), or 3) HORIZONTAL if the intraprediction mode of block X is a “horizontal-type” angular mode (less than or equal to 34) - If intraModeA and intraModeB are the same: o If intraModeA is PLANAR or DC, the three MPMs are prepared as {PLANAR, DC, VERTICAL} in that order o Otherwise, the three MPMs are prepared as {intraModeA, PLANAR, DC} in that order - Otherwise (intraModeA and intraModeB are different): o The first two MPMs are prepared as {intraModeA, intraModeB} in that order o The uniqueness of PLANAR, DC, and VERTICAL is checked in that order with respect to the first two MPM candidate modes; once a unique mode is found, it is added as the third MPM

[136] If the CU shape is too wide or too narrow as defined above, the MPM flag is considered 1 without signaling. Otherwise, an MPM flag is signaled to indicate whether the CIIP intraprediction mode is one of the CIIP MPM candidate modes.

[137] If the MPM flag is 1, an MPM index is additionally flagged to indicate which of the MPM candidate modes is used in CIIP intraprediction. Otherwise, if the MPM flag is 0, the intraprediction mode is prepared for the “absent” mode in the MPM candidate list. For example, if the PLANAR mode is not in the MPM candidate list, then PLANAR is the absent mode and the intraprediction mode is prepared as PLANAR. Since 4 possible intraprediction modes are allowed in CIIP, and the MPM candidate list contains only 3 intraprediction modes, one of the 4 possible modes must be the absent mode.

[138] For chroma components, DM mode is always applied without additional flagging; i.e. chroma uses the same prediction mode as luma.

[139] The intra-prediction mode of a CIIP-coded CU will be saved and used in the intra-mode coding of future neighboring CUs. 2.2.9.2 Combining intra- and inter-prediction signals

[140] The interprediction signal in the CIIP Pinter mode is derived using the same interprediction process as applied to the regular blending mode; and the intraprediction signal Pintra is derived using the CIIP intraprediction mode following the regular intraprediction process. Then, the intra and interprediction signals are combined using weighted average, where the weighting value depending on the intraprediction modes and where the sample is located in the coding block as follows: - If the intraprediction mode is DC or planar mode, or if the block width or height is less than 4, then equal weightings are applied to the intraprediction and interprediction signals. - Otherwise, the weightings are determined based on the intraprediction mode (horizontal mode or vertical mode in this case) and the location of the sample in the block. Take the horizontal prediction mode for example (the weightings for the vertical mode are derived similarly but in the orthogonal direction). Denote W as the block width and H as the block height. The coding block is first divided into four equal area parts, each with dimension (W/4)xH. Starting from the part closest to the intra-prediction reference samples and ending at the part farthest from the intra-prediction reference samples, the weighting wt for each of the 4 regions is prepared as 6, 5, 3 and 2 respectively. The final CIIP prediction signal is derived using the following: PCIIP = ((8 - wt) * Pinter + wt * Pintra + 4) » 3 II. CIIP in VTM5

[141] In VTM5, when a cU is encoded in blend mode, if the cU contains at least 64 luma samples (i.e., the cU width times the cU height is equal to or greater than 64), and if both the cU width and the cU height are less than 128 luma samples, an additional flag is set to indicate whether the combined inter/intra prediction (ciip) mode is applied to the current cU. As its name implies, ciip prediction combines an interprediction signal with an intraprediction signal. The interprediction signal in the CIIP Pinter mode is derived using the same interprediction process as applied to the regular blend mode; and the intraprediction signal Pintra is derived by following the regular intraprediction process with the planar mode. Then, the intra and inter prediction signals are combined using weighted average, where the weighting value is calculated depending on the coding modes of the top and left neighbor blocks (depicted in FIG. 16) as follows: - If the top neighbor is available and intra-coded, set isIntraTop to 1, otherwise set isIntraTop to 0; - If the left neighbor is available and intra-coded, set isIntraLeft to 1, otherwise set isIntraLeft to 0; - If (isIntraLeft + isIntraTop) is equal to 2, then wt is set to 3; - Otherwise, if (isIntraLeft + isIntraTop) is equal to 1, then wt is set to 2; - Otherwise, set wt to 1.

[142] The CIIP prediction is formed as follows: PPCIIP = ((4 - Wt) * P[nter + w^ * Cintra + 2) » 2

[143] FIG. 16 shows upper and left neighbor blocks used in evaluating CIIP weights 2.3. Intramode Derivation Process

[144] In current VTM-4.0, when encoding an intracoded block, a most probable mode (MPM) flag is first signaled. If the MPM flag is true, the index to an MPM list is additionally signaled. Otherwise, the index of non-MPM modes is signaled.

[145] Related syntax, symmetric and decoding process elements in the latest VVC specification (JVET-M1001_v7) are provided as follows:

Related syntax

[146] Coding unit syntax Semantics

[147] The syntax elements intra_luma_mpm_flag[x0][y0], intra_luma_mpm_idx[x0][y0], and intra_luma_mpm_remainder[x0][y0] specify the intraprediction mode for luma samples. The array indices x0, y0 specify the location (x0, y0) of the top-left luma sample of the considered coding block relative to the top-left luma sample of the image. When intra_luma_mpm_flag[x0][y0] is equal to 1, the intraprediction mode is inferred from a neighboring intrapredicted coding unit according to clause 8.4.2.

[148] When intra_luma_mpm_flag[ x0 ][ y0 ] is not present, it is inferred to be equal to 1.

[149] Decoding Process

[150] Derivation process for luma intraprediction mode

[151] The inputs to this process are: a luma location ( xCb, yCb ) specifying the top-left sample of the current luma coding block relative to the top-left luma sample of the current image, a variable cbWidth specifying the width of the current coding block in luma samples, a variable cbHeight specifying the height of the current coding block in luma samples. In this process, the luma intraprediction mode IntraPredModeY[xCb][yCb] is derived. Table 8-1 specifies the value for the intraprediction mode IntraPredModeY[xCb][yCb] and the associated names. Table 8-1 - Intraprediction mode specification and associated names NOTE - : The intraprediction modes INTRA_LT_CCLM, INTRA_L_CCLM and INTRA_T_CCLM are applicable only to chroma components. IntraPredModeY[xCb][yCb] is derived by the following ordered steps: 1. The neighboring locations (xNbA, yNbA) and (xNbB, yNbB) are prepared as equal to ( xCb - 1, yCb + cbHeight - 1 ) and ( xCb + cbWidth - 1, yCb - 1 ) respectively. 2. For X being replaced by A or B, the variables candIntraPredModeX are derived as follows:- The availability derivation process for a block as specified in clause 6.4.X [Ed. (BB): Neighboring block availability check process tbd] is invoked with location (xCurr, yCurr) prepared equal to (xCb, yCb) and neighboring location (xNbY, yNbY) prepared equal to (xNbX, yNbX) as inputs, and the output is assigned to availableX. - The candidate intraprediction mode candIntraPredModeX is derived as follows: - If one or more of the following conditions are true, candIntraPredModeX is prepared equal to INTRA_PLANAR. - The variable availableX is equal to FALSE. - CuPredMode[xNbX][yNbX] is not equal to MODE_INTRA and ciip_flag[xNbX][yNbX] is not equal to 1. - pcm_flag[ xNbX ][ yNbX ] is equal to 1. - X is equal to B and yCb - 1 is less than ((yCb >> CtbLog2SizeY) << CtbLog2SizeY ). - Otherwise, candIntraPredModeX is set equal to IntraPredModeY[xNbX][yNbX]. 3. The variables ispDefaultMode1 and ispDefaultMode2 are set as follows: - If IntraSubPartitionsSplitType is equal to ISP_HOR_SPLIT, ispDefaultMode1 is set equal to INTRA_ANGULAR18 and ispDefaultMode2 is set equal to INTRA_ANGULAR5. - Otherwise, ispDefaultMode1 is set equal to INTRA_ANGULAR50 and ispDefaultMode2 is set equal to INTRA_ANGULAR63. 4. candModeList[x] with x = 0..5 is derived as follows:- If candIntraPredModeB is equal to candIntraPredModeA and candIntraPredModeA is greater than INTRA_DC, candModeList[x] with x = 0..5 is derived as follows:- If IntraLumaRefLineIdx[xCb][yCb] is equal to 0 and IntraSubPartitionsSplitType is equal to ISP_NO_SPLIT, then the following applies: candModeList[ 0 ] = candIntraPredModeA (8-9) candModeList[ 1 ] = INTRA_PLANAR (8-10) candModeList[ 2 ] = INTRA_DC (8-11) candModeList[ 3 ] = 2 + ( ( candIntraPredModeA + 61 ) % 64 ) (8-12) candModeList[ 4 ] = 2 + ( ( candIntraPredModeA - 1 ) % 64 ) (8-13) candModeList[ 5 ] = 2 + ( ( candIntraPredModeA + 60 ) % 64 ) (8-14) - Otherwise (IntraLumaRefLineIdx[xCb][yCb] is not equal to 0 or IntraSubPartitionsSplitType is not equal to ISP_NO_SPLIT), the following applies: candModeList[ 0 ] = candIntraPredModeA (8-15) candModeList[ 1 ] = 2 + ( ( candIntraPredModeA + 61 ) % 64 ) (8-16) candModeList[ 2 ] = 2 + ( ( candIntraPredModeA - 1 ) % 64 ) (8-17) - If either of the following conditions is true, - IntraSubPartitionsSplitType is equal to ISP_HOR_SPLIT and candIntraPredModeA is less than INTRA_ANGULAR34, - IntraSubPartitionsSplitType is equal to ISP_VER_SPLIT and candIntraPredModeA is greater than or equal to INTRA_ANGULAR34, - IntraLumaRefLineIdx[xCb][yCb] is not equal to 0, then the following applies: candModeList[ 3 ] = 2 + ( ( candIntraPredModeA + 60 ) % 64 ) (8-18) candModeList[ 4 ] = 2 + ( candIntraPredModeA % 64 ) (8-19) candModeList[ 5 ] = 2 + ( ( candIntraPredModeA + 59 ) % 64 ) (8-20) - Otherwise, the following applies: candModeList[ 3 ] = ispDefaultMode1 (8-21) candModeList[ 4 ] = ispDefaultMode2 (8-22) candModeList[ 5 ] = INTRA_PLANAR (8-23) - Otherwise, if candIntraPredModeB is not equal to candIntraPredModeA and either candIntraPredModeA or candIntraPredModeB is greater than INTRA_DC, the following applies: - The variables minAB and maxAB are derived as follows: minAB = Min( candIntraPredModeA, candIntraPredModeB ) (8-24) maxAB = Max( candIntraPredModeA, candIntraPredModeB ) (8-25) - If candIntraPredModeA and candIntraPredModeB are greater than INTRA_DC, candModeList[x] with x = 0..5 is derived as follows: candModeList[ 0 ] = candIntraPredModeA (8-26) candModeList[ 1 ] = candIntraPredModeB (8-27) - If IntraLumaRefLineIdx[xCb][yCb] is equal to 0 and IntraSubPartitionsSplitType is equal to ISP_NO_SPLIT, then the following applies: candModeList[ 2 ] = INTRA_PLANAR (8-28) candModeList[ 3 ] = INTRA_DC (8-29) - If maxAB - minAB is in the range 2 to 62 inclusive, then the following applies: candModeList[ 4 ] = 2 + ( ( maxAB + 61 ) % 64 ) (8-30) candModeList[ 5 ] = 2 + ( ( maxAB - 1 ) % 64 ) (8-31) - Otherwise, the following applies: candModeList[ 4 ] = 2 + ( ( maxAB + 60 ) % 64 ) (8-32) candModeList[ 5 ] = 2 + ( ( maxAB ) % 64 ) (8-33) - Otherwise (IntraLumaRefLineIdx[xCb][yCb] is not equal to 0 or IntraSubPartitionsSplitType is not equal to ISP_NO_SPLIT), the following applies: - When IntraSubPartitionsSplitType is not equal to ISP_NO_SPLIT and abs(candIntraPredModeB - ispDefaultMode1) is less than abs (candIntraPredModeA - ispDefaultMode1), the following applies: candModeList[ 0 ] = candIntraPredModeB (8-34) candModeList[ 1 ] = candIntraPredModeA (8-35) - If maxAB - minAB is equal to 1, the following applies: candModeList[ 2 ] = 2 + ( ( minAB + 61 ) % 64 ) (8-36) candModeList[ 3 ] = 2 + ( ( maxAB - 1 ) % 64 ) (8-37) candModeList[ 4 ] = 2 + ( ( minAB + 60 ) % 64 ) (8-38) candModeList[ 5 ] = 2 + ( maxAB % 64 ) (8-39) - Otherwise if maxAB - minAB is equal to 2, the following applies: candModeList[ 2 ] = 2 + ( ( minAB - 1 ) % 64 ) (8-40) candModeList[ 3 ] = 2 + ( ( minAB + 61 ) % 64 ) (8-41) candModeList[ 4 ] = 2 + ( ( maxAB - 1 ) % 64 ) (8-42) candModeList[ 5 ] = 2 + ( ( minAB + 60 ) % 64 ) (8-43) - Otherwise, if maxAB - minAB is greater than 61, the following applies: candModeList[ 2 ] = 2 + ( ( minAB - 1 ) % 64 ) (8-44) candModeList[ 3 ] = 2 + ( ( maxAB + 61 ) % 64 ) (8-45) candModeList[ 4 ] = 2 + ( minAB % 64 ) (8-46) candModeList[ 5 ] = 2 + ( ( maxAB + 60 ) % 64 ) (8-47) - Otherwise, the following applies: candModeList[ 2 ] = 2 + ( ( minAB + 61 ) % 64 ) (8-48) candModeList[ 3 ] = 2 + ( ( minAB - 1 ) % 64 ) (8-49) candModeList[ 4 ] = 2 + ( ( maxAB + 61 ) % 64 ) (8-50) candModeList[ 5 ] = 2 + ( ( maxAB - 1 ) % 64 ) (8-51) - Otherwise (either candIntraPredModeA or candIntraPredModeB is greater than INTRA_DC), candModeList [x] with x = 0..5 is derived as follows: - If IntraLumaRefLineIdx [xCb] [yCb] equals 0 and IntraSubPartitionsSplitType equals ISP_NO_SPLIT, the following applies: candModeList[ 0 ] = candIntraPredModeA (8-52) candModeList[ 1 ] = candIntraPredModeB (8-53) candModeList[ 2 ] = 1 - minAB (8-54) candModeList[ 3 ] = 2 + ( ( maxAB + 61 ) % 64 ) (8-55) candModeList[ 4 ] = 2 + ( ( maxAB - 1 ) % 64 ) (8-56) candModeList[ 5 ] = 2 + ( ( maxAB + 60 ) % 64 ) (8-57) - Otherwise, if IntraLumaRefLineIdx [xCb] [yCb] is not equal to 0, the following applies: candModeList[ 0 ] = maxAB (8-58) candModeList[ 1 ] = 2 + ( ( maxAB + 61 ) % 64 ) (8-59) candModeList[ 2 ] = 2 + ( ( maxAB - 1 ) % 64 ) (8-60) candModeList[ 3 ] = 2 + ( ( maxAB + 60 ) % 64 ) (8-61) candModeList[ 4 ] = 2 + ( maxAB % 64 ) (8-62) candModeList[ 5 ] = 2 + ( ( maxAB + 59 ) % 64 ) (8-63) - Otherwise (IntraSubPartitionsSplitType is not equal to ISP_NO_SPLIT), the following applies: candModeList[ 0 ] = INTRA_PLANAR (8-64) candModeList[ 1 ] = maxAB (8-65) candModeList[ 2 ] = 2 + ( ( maxAB + 61 ) % 64 ) (8-66) candModeList[ 3 ] = 2 + ( ( maxAB - 1 ) % 64 ) (8-67) candModeList[ 4 ] = 2 + ( ( maxAB + 60 ) % 64 ) (8-68) candModeList[ 5 ] = 2 + ( maxAB % 64 ) (8-69) - Otherwise, the following applies: - If IntraLumaRefLineIdx[xCb][yCb] is equal to 0 and IntraSubPartitionsSplitType is equal to ISP_NO_SPLIT, the following applies: candModeList[ 0 ] = candIntraPredModeA (8-70) candModeList[ 1 ] = ( candModeList[0] = = INTRA_PLANAR ) ? INTRA_DC : (8-71) INTRA_PLANAR candModeList[ 2 ] = INTRA_ANGULAR50 (8-72) candModeList[ 3 ] = INTRA_ANGULAR18 (8-73) candModeList[ 4 ] = INTRA_ANGULAR46 (8-74) candModeList[ 5 ] = INTRA_ANGULAR54 (8-75) - Otherwise, if IntraLumaRefLineIdx[xCb][yCb] is not equal to 0, the following applies: candModeList[ 0 ] = INTRA_ANGULAR50 (8-76) candModeList[ 1 ] = INTRA_ANGULAR18 (8-77) candModeList[ 2 ] = INTRA_ANGULAR2 (8-78) candModeList[ 3 ] = INTRA_ANGULAR34 (8-79) candModeList[ 4 ] = INTRA_ANGULAR66 (8-80) candModeList[ 5 ] = INTRA_ANGULAR26 (8-81) - Otherwise, if IntraSubPartitionsSplitType is equal to ISP_HOR_SPLIT, the following applies: candModeList[ 0 ] = INTRA_PLANAR (8-82) candModeList[ 1 ] = INTRA_ANGULAR18 (8-83) candModeList[ 2 ] = INTRA_ANGULAR25 (8-84) candModeList[ 3 ] = INTRA_ANGULAR10 (8-85) candModeList[ 4 ] = INTRA_ANGULAR65 (8-86) candModeList[ 5 ] = INTRA_ANGULAR50 (8-87) - Otherwise, if IntraSubPartitionsSplitType is equal to ISP_VER_SPLIT, the following applies: candModeList[ 0 ] = INTRA_PLANAR (8-88) candModeList[ 1 ] = INTRA_ANGULAR50 (8-89) candModeList[ 2 ] = INTRA_ANGULAR43 (8-90) candModeList[ 3 ] = INTRA_ANGULAR60 (8-91) candModeList[ 4 ] = INTRA_ANGULAR3 (8-e) candModeList[ 5 ] = INTRA_ANGULAR18 (8-93) 5. IntraPredModeY[xCb][yCb] is derived by applying the following procedure:- If intra_luma_mpm_flag[xCb][yCb] is equal to 1, then IntraPredModeY[xCb][yCb] is set equal to candModeList [intra_luma_mpm_idx[xCb][yCb]]. - Otherwise, IntraPredModeY[xCb][yCb] is derived by applying the following ordered steps: 1. When candModeList[i] is greater than candModeList[j] for i = 0..4 and for each i, j = (i 1) .. 5, both values are swapped as follows: ( candModeList[ i ], candModeList[ j ] ) = Swap( candModeList[ i ], candModeList[ j ] ) (8-94) 2. IntraPredModeY[xCb][yCb] is derived by the following ordered steps: i. IntraPredModeY[xCb][yCb] is set equal to intra_luma_mpm_remainder[xCb][yCb]. ii. For i equal to 0 through 5 inclusive, when IntraPredModeY[xCb][yCb] is greater than or equal to candModeList[i], the value of IntraPredModeY[xCb][yCb] is incremented by one. The variable IntraPredModeY[ x ][ y ] with x = xCb..xCb + cbWidth - 1 and y = yCb..yCb + cbHeight - 1 is set to be equal to IntraPredModeY[xCb][yCb].

3. Examples of Problems Solved by the Modalities

[152] In LIC, two parameters including scale parameter and offset b need to be derived using neighboring reconstructed samples, which may cause latency issues.

[153] The set of allowed weighting factors used in the GBI are fixed, which can be inefficient.

[154] CIIP mode is only applied to non-skip blending mode, which can be inefficient.

[155] In the current design, the CIIP mode flag must be stored, since for the intramode derivation process of the intracoded block and for the intramode derivation process of CIIP-coded blocks, the CIIP mode flag of the neighboring blocks is used.

[156] In the current design, the weighting derivation of CIIP can be improved, for example, checking two neighboring blocks and three different weight pairs can be simplified.

[157] In the current design, during the CIIP weighting derivation process, if a neighboring block is coded with BDPCM mode, it is treated as intramode. However, it may be more reasonable to treat it as non-intramode since BDPCM is designed for screen content coding.

4. Examples of modalities

[158] Hereafter, a block is used to represent a transform unit (TU)/prediction unit (PU)/coding unit (CU)/a sub-block within a TU/PU/CU etc.

[159] The techniques detailed below should be considered as examples to explain the general concepts. These techniques should not be interpreted narrowly. Furthermore, these techniques can be combined in any way.

[160] Suppose (xCb, yCb) is the location of the top-left sample of the current block relative to the top-left sample of the current image, cbWidth and cbHeight specify the width and height of the current block. 1. CIIP flag or/and LIC flag or/and diffusion filtering flag or/and bilateral filtering flag or/and transform domain filtering flag or/and activation flag of other types of post-reconstruction filter may be restricted to be false (and CIIP or/and LIC or/and diffusion filter or/and bilateral filter or/and transform domain filter may be implicitly disabled) depending on the coded modes of other blocks (such as adjacent or non-adjacent neighboring blocks and/or reference blocks). a. When a flag is derived to be false, the corresponding method cannot be applied. b. When a flag is derived to be false, the flagging of indications of use of such modes is skipped. c. When a flag is derived to be false, indications of use of such modes may still be signaled, but are restricted to being false in a conforming bitstream, and such modes are not enforced. d. In an example, whether or not to enforce one or more proposed constraints (such as 1.a, 1.b, and 1.c) may depend on the encoded modes of all or some of the adjacent and/or non-adjacent neighboring rows or columns. i. Alternatively, whether or not to enforce such a constraint may depend on at least N (N>=1) of the samples in the adjacent or non-adjacent neighboring row or columns that are NOT encoded with certain modes. e. In an example, the adjacent and/or non-adjacent neighboring rows may include the row above and/or the row above the right. f. In an example, the neighboring and/or non-adjacent columns may include the left column and/or the lower-left and/or upper-left corner. g. In an example, certain modes of a block other than the current block may include intramode and/or CIIP mode and/or CPR mode. h. In an example, if any of the neighboring/non-adjacent blocks in the neighboring and/or non-adjacent rows or columns are coded with the given mode (e.g., intramode and/or CIIP mode and/or RCP mode), one or multiple proposed constraints (such as 1.a, 1.b, and 1.c) are applied. i. In an example, if all neighboring/non-adjacent blocks in the adjacent and/or non-adjacent neighboring rows or columns are coded with the given mode (e.g., intramode and/or CIIP mode and/or CPR mode), one or multiple proposed constraints are applied. j. In an example, if at least N neighboring/non-adjacent blocks in the neighboring or non-adjacent row or columns are NOT encoded with the certain mode (e.g., intramode and/or CIIP mode and/or RCP mode), one or multiple proposed constraints (such as 1.a, 1.b, and 1.c) are NOT applied. k. In an example, whether or not one or multiple proposed constraints (such as 1.a, 1.b, and 1.c) are applied may depend on the position of the current block. i. In an example, if the current block is at the top of the current CTU (the current block and its neighboring block above it belong to different CTUs), the proposed constraints are NOT applied. ii. In an example, if the current block is to the left of the current CTU (the current block and its neighboring block to the left belong to different CTUs), the proposed constraints are NOT applied. 2. CIIP and/or intramode flag of CIIP mode can be stored together with motion information in the history-based motion vector prediction (HMVP) table. a. In one example, when comparing the motion information of two candidates (such as the pruning process), the CIIP or/and intramode flag in CIIP mode are not considered in the comparison. b. In one example, when comparing the motion information of two candidates, the CIIP or/and intramode flag in CIIP mode are considered in the comparison. c. In one example, when a merge candidate is from an entry in the HMVP table, the CIIP flag of that entry is also copied to the merge candidate. d. In one example, when a merge candidate is from an entry in the HMVP table, the CIIP and intramode flag of that entry are also copied to the merge candidate. 3. CIIP can be performed for AMVP mode (AMVP or/and AMVP mode with SMVD mode) a. The CIIP and/or intramode flag in CIIP mode of neighboring/non-adjacent blocks can be inherited in merge mode or/and current block mode of UMVE (also known as merge with motion vector difference, MMVD for short). b. The CIIP and/or intramode flag in CIIP mode can be signaled for non-hop merge mode or/and non-hop UMVE mode, and the CIIP and/or intramode flag in CIIP mode of neighboring/non-adjacent blocks can be inherited in skip merge mode or/and skip UMVE mode. c. The CIIP and/or intramode flag in CIIP mode can be signaled for skip merge mode or/and skip UMVE mode, and the CIIP and/or intramode flag in CIIP mode of neighboring/non-adjacent blocks can be inherited in non-hop merge mode or/and skip UMVE mode. d. In an example, the CIIP flag and an intramode may be flagged for AMVP mode. e. In an example, the CIIP flag may be inherited in merge mode or/and UMVE mode, and if the CIIP flag is true, an intramode may be additionally flagged if more than one intramode is allowed in CIIP. f. In an example, the CIIP flag and the intramode of neighboring/nonadjacent blocks in merge mode or/and UMVE mode may be inherited by the current block. g. In an example, CIIP may be disabled for hop mode. h. In an example, when comparing two merge candidates, the CIIP flag or/and intramode in CIIP may not be considered in the comparison. i. In an example, when comparing two merge candidates, the CIIP flag or/and intramode in CIIP may be considered in the comparison. 4. CIIP may be disabled for pairwise prediction or bicombined prediction or other types of virtual/artificial candidates (e.g., zero-motion vector candidates). i. Alternatively, if one of the two candidates involved in the pairwise prediction or bicombined prediction adopts CIIP prediction, CIIP may be enabled for the pairwise or bicombined merge candidate. ii. In an example, the intra mode of the CIIP mode candidate may be inherited. iii. In an example, the intra mode may be explicitly flagged. b. Alternatively, if both candidates involved in the pairwise prediction or bicombined prediction adopt CIIP prediction, CIIP may be enabled for the pairwise or bicombined merge candidate. iv. In an example, the intra mode of one of two candidates may be inherited. v. In an example, an intra mode may be derived from the intra modes of the two candidates and is used for the pairwise or bicombined merge candidate. vi. In one example, the intra mode may be explicitly flagged. 5. Spatially neighboring and/or non-adjacent reconstructed samples required in the CIIP mode or/and diffusion filter or/and bilateral filter or/and transform domain filter or/and other types of post-reconstruction filter may be replaced by the corresponding samples in the reference images (such as spatially neighboring and/or non-adjacent samples of the reference block, as shown in FIG. 17). a. In one example, if the current block is bipredicted, neighboring samples from the two reference blocks may be averaged to generate the final neighboring samples. b. In one example, if the current block is bipredicted, neighboring samples from one of the two reference blocks may be used as the final neighboring samples. c. In one example, if the current block is bipredicted, neighboring samples from the two reference blocks may be averaged to generate the final neighboring samples if unequal-weighted GBI or weighted prediction or LIC is applied to the current block. d. In one example, corresponding samples in reference images (e.g., neighboring samples of the reference block) can be identified by the motion information of the current block. e. In one example, corresponding samples in reference images (e.g., neighboring samples of the reference block) can be identified by the modified motion information of the current block. For example, the motion vector can be rounded to integer precision before being used to identify neighboring samples. f. In one example, corresponding samples in reference images (e.g., neighboring samples of the reference block) are identified using motion vectors with integer precision pel. i. In one example, the MV for the reference block is first rounded to an integer pixel. The rounded MV is used to identify neighboring samples of the reference block. ii. In one example, the proposed replacement is applied when the current block is encoded with integer motion information pel. Therefore, no rounding is required. g. In one example, the proposed replacement can be applied for a certain color component, such as only the luma component. i. Alternatively, the proposed replacement may be applied to all color components. 6. It is proposed to prohibit the use of previously encoded CIIP flags for encoding subsequent blocks. a. In one example, the process of checking CIIP flags of previously encoded blocks is skipped to improve throughput. b. In one example, the process of checking CIIP flags of neighboring blocks in the intramode derivation process is skipped. i. In one example, for a neighboring block, if it is encoded with CIIP mode, the associated intramode may be set to a certain mode (such as Planar mode). Alternatively, in addition, the associated intramode may be used in the MPM list derivation process. ii. In one example, for a neighboring block, if it is encoded with CIIP mode or normal intermode, the associated intramode may be set to a certain mode (such as Planar mode). Alternatively, in addition, the associated intramode may be used in the MPM list derivation process. iii. In one example, the intramode of CIIP-encoded blocks may not be stored and the CIIP-encoded blocks may be considered unavailable in the decoding process. Alternatively, the CIIP-encoded blocks may be treated in the same manner as normal intermodes. c. Alternatively, in addition, it is proposed to remove the CIIP flag from memory to save the memory size required to store mode information. 7. It is proposed that the CIIP mode flag be encoded by bypass coding. a. Alternatively, the CIIP mode flag may be encoded in context but without referring to the CIIP mode flags of neighboring blocks. 8. It is proposed that the approach to doing weighted summation in CIIP may depend on the color components. a. For example, the weighting values in CIIP are different for the main color component (e.g., G component) and other color components (e.g., B and R components). b. For example, the weighting values in CIIP are different for the luma component and the chroma components. c. For example, the weighting values for inter-prediction and intra-prediction are the same in the chroma components. 9. It is proposed that when the weighting factor selection is according to neighboring blocks, for a neighboring block, if coded as CIIP mode, it can be treated as the inter-coded block. a. Alternatively, when the weighting factor selection is according to neighboring blocks, for a neighboring block, if coded as CIIP mode, it can be treated as the intra-coded block. 10. The above proposed method can be applied under certain conditions, such as block sizes, slice/image/tile types, or motion information. a. In one example, when a block size contains samples smaller than M*H, for example, 16 or 32 or 64 luma samples, the proposed method is not allowed. b. Alternatively, when the minimum size of the width and/or height of a block is smaller or not larger than X, the proposed method is not allowed. In one example, X is prepared as 8. c. Alternatively, when the minimum size of a block's width and/or height is not less than X, the proposed method is not allowed. In an example, X is prepared as 8. d. Alternatively, when a block's width > th1 or >=th1 and/or a block's height > th2 or >=th2, the proposed method is not allowed. In an example, th1 and/or th2 is prepared as 8. e. Alternatively, when a block's width < th1 or <=th1 and/or a block's height < th2 or <a=th2, the proposed method is not allowed. In an example, th1 and/or th2 is prepared as 8. 11. The number of allowed weight pairs (wIntra, wInter) used in CIIP can be reduced from 3 to 2, denoted as (a, b) and (c, d). a. In an example, two pairs are defined as {(1,3) and (3,1)}; or {(1,3) and (2, 2)}; or {(3,1) and (2, 2)}; or {(3, 5) and (4, 4)} or {(5, 3) and (4, 4)}, or {(1, 7) and (4, 4)} or {(7, 1) and (4, 4)}. b. In one example, the weight pair is determined based on only one neighboring block A. i. In one example, if a neighboring block A is available and intra-coded, (wIntra, wInter) is set equal to (a, b); otherwise, (wIntra, wInter) is set equal to (c, d). ii. In one example, block A is a left neighboring block. iii. In one example, block A is an up neighboring block. c. In an example, the weight pair is determined based on two or more neighboring blocks, and for at least one of the neighboring blocks, certain conditions are satisfied. 1. In an example, if at least one of the neighboring blocks A and B are available and intracoded, (wIntra, wInter) is set equal to (a, b); Otherwise, (wIntra, wInter) is set equal to (c, d). 2. In an example, block A is a left neighboring block and B is an up neighboring block. d. In an example, the weight pair is determined based on two or more neighboring blocks, and for each of the neighboring blocks, the same conditions are satisfied. i. In an example, if the neighboring blocks A and B are both available and intracoded, (wIntra, wInter) is set equal to (a, b); Otherwise, (wIntra, wInter) is set equal to (c, d). 1. In an example, block A is a left neighboring block and B is an up neighboring block. e. In an example, the configurations of (a, b) and (c, d) may be as follows: 1. In an example, (a, b) is set to (2, 2) or (3, 1). 2. In an example, (c, d) is set to (1, 3). 3. In an example, at least one of two conditions is true: a is not equal to c or b is not equal to d. 4. (a, b) is not equal to (c, d). f. In an example, the neighboring block (e.g., A or B) mentioned above is an adjacent or non-adjacent spatial neighboring block or a temporal neighboring block. i. In an example, neighboring block A or B is the left (or top) neighboring block. ii. In an example, neighboring blocks A and B are the left and top neighboring blocks, respectively. iii. In an example, the left neighboring block covers the location (xCb - 1, yCb + cbHeight - 1). iv. In one example, the top neighboring block covers the location (xCb + cbWidth - 1, yCb - 1). v. In one example, the left neighboring block covers the location (xCb - 1, yCb). vi. In one example, the top neighboring block covers the location (xCb, yCb - 1). g. For the above examples, the CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wlntra * Pintra + offset) » N where Offset is prepared as (1 << (N-1)) or 0, and N can be prepared as log2(wIntra + wInter). 12. The number of allowed weight pairs (wIntra, wInter) used in CIIP can be reduced from 3 to 1. a. In one example, the weight pair is defined as (1,3) or (2, 2) or (1,7) or (2, 6) or (3, 5) or (4, 4). b. In one example, (wIntra, wInter) is set equal to (2, 2). c. In one example, (wIntra, wInter) is set equal to (1, 3). d. For the above examples, the CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wlntra * Pintra + offset) » N where Offset is set as (1 << (N-1)) or 0, and N can be set as log2(wIntra + wInter). 13. The weight pairs (wIntra, wInter) can be derived based on whether one or multiple neighboring blocks are encoded with CIIP mode. a. The weight pair used for the current block can be derived from the one used for a previously encoded block. b. In one example, the weight pair is determined based on only one neighboring block A. i. In an example, if a neighboring block A is coded with CIIP mode, (wIntra, wInter) of the current block is prepared equal to (wIntra, wInter) of the neighboring block A; otherwise, if the neighboring block A is available and intracoded, (wIntra, wInter) is prepared equal to (a, b); otherwise, (wIntra, wInter) is prepared equal to (c, d). ii. In an example, if a neighboring block A is coded with CIIP mode, (wIntra, wInter) of the current block is prepared equal to (wIntra, wInter) of the neighbor; otherwise, (wIntra, wInter) is prepared equal to (a, b). iii. For the above examples, the following may apply: 1. In an example, (a, b) is prepared equal to (2, 2) or (3, 1). 2. In an example, (c, d) is prepared equal to (1, 3). 3. In an example, at least one of two conditions is true: a is different from c; b is different from d. c. In an example, the weight pair is determined based on two or more neighboring blocks, and for at least one of the neighboring blocks, certain conditions are satisfied. i. Multiple neighboring blocks may be checked in a certain checking order (e.g., first checking the left block and then checking the top block) to identify the use of CIIP mode. ii. In an example, if at least one of the neighboring blocks A and B is encoded with CIIP mode, (wIntra, wInter) of the current block is set equal to (wIntra, wInter) of the first neighboring block encoded with CIIP in a certain checking order; otherwise, if at least one neighboring block of A and B is available and intra-coded, (wIntra, wInter) is set equal to (a, b); otherwise, (wIntra, wInter) is set equal to (c, d). iii. For the above examples, the following may apply: 1. In an example, (a, b) is set equal to (2, 2) or (3, 1). 2. In an example, (c, d) is set equal to (1, 3). 3. In an example, at least one of two conditions is true: a is not equal to c; b is not equal to d. iv. In an example, if at least one of the neighboring blocks A and B is coded with CIIP mode, (wIntra, wInter) of the current block is set equal to (wIntra, wInter) of the first neighboring CIIP-coded block in a given check order; otherwise, if the neighboring blocks A and B are both available and intra-coded, (wIntra, wInter) is set equal to (a, b); otherwise, (wIntra, wInter) is set equal to (c, d). v. In an example, if at least one of the neighboring blocks A and B is coded with CIIP mode, (wIntra, wInter) of the current block is set equal to (wIntra, wInter) of the first neighboring block coded of CIIP in a given scan order; otherwise, (wIntra, wInter) is set equal to (c, d). vi. For the above examples, the following may apply: 1. In an example, (c, d) is set equal to (2, 2) or (1, 3). d. In an example, the above-mentioned neighboring block A or B is an adjacent or non-adjacent spatial neighboring block or a temporal neighboring block. i. In an example, neighboring block A or B is the left (or top) neighboring block. ii. In an example, neighboring blocks A and B are the left and top neighboring blocks, respectively. iii. In an example, the left neighboring block covers the location (xCb - 1, yCb + cbHeight - 1). iv. In one example, the top neighboring block covers the location (xCb + cbWidth - 1, yCb - 1). v. In one example, the left neighboring block covers the location (xCb - 1, yCb). vi. In one example, the top neighboring block covers the location (xCb, yCb - 1). e. For the above examples, the CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wlntra * Pintra + offset) » N where Offset is prepared as (1 << (N-1)) or 0, and N can be prepared as log2(wIntra + wInter). 14. The selection of neighboring blocks used in CIIP may be dependent on the encoded information, such as block dimension/block shape/low-delay check flag/reference image information/current block motion information, and neighboring blocks/intra-prediction modes of neighboring blocks. 15. The weight pairs used in CIIP may be dependent on the encoded information, such as block size/block shape/low delay check flag/reference image information/motion information of the current block and neighboring blocks/intra-prediction modes of neighboring blocks. a. In one example, the set of weight pairs is additionally flagged. b. In one example, the selection of the weight pair may depend on whether a neighboring block is inter-coded rather than intra-coded. 16. When determining CIIP information, (e.g., in determining weights applied to the intra-prediction signal or inter-prediction signal for previous project and markers mentioned above), if a neighboring block is not encoded with MODE_INTRA (i.e., intra-mode), it may be treated as intra-coded. a. In one example, if the neighboring block is IBC-encoded. b. In one example, if the neighboring block is CIIP-encoded. c. In one example, if the neighboring block is TPM-encoded. d. In an example, if the neighboring block is palette coded. e. In an example, if the neighboring block is RDPCM coded. f. In an example, if the neighboring block is coded without transform (e.g., transform skip mode) and/or quantization applied (e.g., transform bypass quantization mode). g. Alternatively, if the neighboring block is coded with a mode mentioned in the above sub-bullets (e.g., IBC, RDPCM, Palette), the neighboring block may be treated as non-intra-coded (e.g., inter-coded). h. In an example, if the neighboring block is intra-coded but NOT coded with certain prediction modes (e.g., Planar), the neighboring block may be treated as non-intra-coded (e.g., inter-coded). i. Alternatively, if the neighboring block is coded with matrix-based intraprediction method and/or multiple reference line intraprediction method with reference line index other than K (e.g., K = 0) and/or BDPCM, the neighboring block can be treated as non-intracoded (e.g., intercoded). j. The proposed methods can be applied to other coding tools that depend on whether a neighboring block is coded with intramode or not. k. The proposed methods can be applied to other coding tools that depend on whether a neighboring block is coded with intermode or not. 17. Enabling or disabling the above methods can be flagged in SPS/PPS/VPS/sequence header/image header/slice header/tile group header/tile/CTU group etc. al. a. Alternatively, which method to use may be signaled in SPS/PPS/VPS/sequence header/picture header/slice header/tile group header/CTU group etc. al. b. Alternatively, enabling or disabling the above methods and/or which method to apply may be dependent on the block size, video data processing unit (VPDU), picture type, low delay check flag, encoded information of the current block (such as reference pictures, uni- or bi-prediction) or previously encoded blocks. 5. Embodiments 5.1 Embodiment 1

[161] An example of checking for skipped CIIP flags of previously encoded blocks is given as follows. 8.4.2 Derivation process for luma intraprediction mode The inputs to this process are: - a luma location (xCb, yCb) specifying the top-left sample of the current luma coding block relative to the top-left luma sample of the current image, - a variable cbWidth specifying the width of the current coding block in luma samples, - a variable cbHeight specifying the height of the current coding block in luma samples. In this process, the luma intraprediction mode IntraPredModeY[xCb][yCb] is derived. Table 8-1 specifies the value for the intraprediction mode IntraPredModeY[xCb][yCb] and the associated names. Table 8-1 - Intraprediction mode specification and associated names NOTE - : The intraprediction modes INTRA_LT_CCLM, INTRA_L_CCLM and INTRA_T_CCLM are applicable only to chroma components. IntraPredModeY[xCb][yCb] is derived by the following ordered steps: 1. The neighboring locations (xNbA, yNbA) and (xNbB, yNbB) are prepared as equal to ( xCb - 1, yCb + cbHeight - 1 ) and ( xCb + cbWidth - 1, yCb - 1 ) respectively. 2. For X being replaced by A or B, the variables candIntraPredModeX are derived as follows:- The availability derivation process for a block as specified in clause 6.4.X [Ed. (BB): Neighboring block availability check process tbd] is invoked with location (xCurr, yCurr) prepared equal to (xCb, yCb) and neighboring location (xNbY, yNbY) prepared equal to (xNbX, yNbX) as inputs, and the output is assigned to availableX. - The candidate intraprediction mode candIntraPredModeX is derived as follows: - If one or more of the following conditions are true, candIntraPredModeX is prepared equal to INTRA_PLANAR. - The variable availableX is equal to FALSE. - CuPredMode[xNbX][yNbX] is not equal to MODE_INTRA. - pcm_flag[ xNbX ][ yNbX ] is equal to 1. - X is equal to B and yCb - 1 is less than ( ( yCb >> CtbLog2SizeY ) << CtbLog2SizeY ). - Otherwise, candIntraPredModeX is set equal to IntraPredModeY[xNbX][yNbX]. 3. The variables ispDefaultMode1 and ispDefaultMode2 are defined as follows: - If IntraSubPartitionsSplitType is equal to ISP_HOR_SPLIT, ispDefaultMode1 is set equal to INTRA_ANGULAR18 and ispDefaultMode2 is set equal to INTRA_ANGULAR5. - Otherwise, ispDefaultMode1 is set equal to INTRA_ANGULAR50 and ispDefaultMode2 is set equal to INTRA_ANGULAR63. 4. The candModeList[x] with x = 0..5 is derived as follows: Mode 2

[162] If the left neighbor is available and intracoded, (wIntra, winter) is prepared as equal to (2, 2); otherwise, (wIntra, wInter) is prepared as equal to (1, 3).

[163] The CIIP prediction is formed as follows: PciiP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 3

[164] If the left neighbor is available and intracoded, (wIntra, wInter) is prepared equal to (3, 1); otherwise, (wIntra, wInter) is prepared equal to (1, 3).

[165] The CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 4

[166] If the upper neighbor is available and intracoded, (wIntra, wInter) is prepared as equal to (2, 2); otherwise, (wIntra, wInter) is prepared as equal to (1, 3).

[167] The CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 5

[168] If the upper neighbor is available and intracoded, (wIntra, wInter) is prepared as equal to (3, 1); otherwise, (wIntra, wInter) is prepared as equal to (1, 3).

[169] The CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 6

[170] If the upper left neighbor is available and intracoded, (wIntra, wInter) is prepared as equal to (2, 2); otherwise, (wIntra, wInter) is prepared as equal to (1, 3).

[171] The CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 7

[172] If the upper left neighbor is available and intracoded, (wIntra, wInter) is prepared as equal to (3, 1); otherwise, (wIntra, wInter) is prepared as equal to (1, 3).

[173] The CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 8

[174] If the upper left neighbor is available and intracoded, (wIntra, wInter) is prepared equal to (2, 2); otherwise, (wIntra, wInter) is prepared equal to (1, 3).

[175] The CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 9

[176] If the left neighbor e is available and intracoded, (wIntra, wInter) is prepared equal to (3, 1); otherwise, (wIntra, wInter) is prepared equal to (1, 3).

[177] The prediction of CIIP is formed as follows: PCIIP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 10 (wIntra, wInter) is prepared equal to (2, 2).

[178] The CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 11 (wIntra, winter) is prepared equal to (1, 3).

[179] The CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 12

[180] If the left neighbor is CIIP-encoded, (wIntra, winter) of the current block is prepared equal to (wIntra, wInter) of the left neighbor; otherwise, if the left neighbor is available and intra-encoded, (wIntra, wInter) is prepared equal to (3, 1); otherwise, (wIntra, wInter) is prepared equal to (1, 3).

[181] The CIIP prediction is formed as follows: PCIIP = (wlnter * Pinter + wIntra * Pintra + 2) » 2 Mode 13

[182] If the left neighbor is CIIP-encoded, (wIntra, wInter) of the current block is prepared equal to (wIntra, wInter) of the left neighbor; otherwise, if the left neighbor is available and intra-encoded, (wIntra, wInter) is prepared equal to (2, 2); otherwise, (wIntra, wInter) is prepared equal to (1, 3).

[183] The CIIP prediction is formed as follows: PCIIP = (wlnter * Pinter + wIntra * Pintra + 2) » 2 Mode 14

[184] If the upper neighbor is CIIP-encoded, (wIntra, wInter) of the current block is prepared equal to (wIntra, wInter) of the upper neighbor; otherwise, if the upper neighbor is available and intra-encoded, (wIntra, wInter) is prepared equal to (3, 1); otherwise, (wIntra, wInter) is prepared equal to (1, 3).

[185] The CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 15

[186] If the upper neighbor is CIIP-encoded, (wIntra, winter) of the current block is prepared equal to (wIntra, wInter) of the upper neighbor; otherwise, if the upper neighbor is available and intra-encoded, (wIntra, wInter) is prepared equal to (3, 1); otherwise, (wIntra, wInter) is prepared equal to (2, 2).

[187] The CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 16

[188] If the left or/and upper neighbor is/are CIIP-encoded, (wIntra, wInter) of the current block is prepared equal to (wIntra, wInter) of the first CIIP-encoded neighbor (left->upper); otherwise, if the left or/and upper neighbor is/are available and intra-encoded, (wIntra, wInter) is prepared equal to (3, 1); otherwise, (wIntra, wInter) is prepared equal to (1, 3).

[189] The CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 17

[190] If the left or/and upper neighbor is/are CIIP-encoded, (wIntra, wInter) of the current block is prepared equal to (wIntra, wInter) of the first CIIP-encoded neighbor (left->upper); otherwise, if the left or/and upper neighbor is/are available and intra-encoded, (wIntra, wInter) is prepared equal to (2, 2); otherwise, (wIntra, wInter) is prepared equal to (1, 3).

[191] The CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 18

[192] If the left neighbor is CIIP encoded, (wIntra, wInter) of the current block is prepared equal to (wIntra, wInter) of the left neighbor; otherwise, (wIntra, wInter) is prepared equal to (1, 3).

[193] The CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 19

[194] If the left neighbor is CIIP encoded, (wIntra, wInter) of the current block is prepared equal to (wIntra, wInter) of the left neighbor; otherwise, (wIntra, wInter) is prepared equal to (2, 2).

[195] The CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 20

[196] If the upper neighbor is CIIP encoded, (wIntra, wInter) of the current block is prepared equal to (wIntra, wInter) of the upper neighbor; otherwise, (wIntra, wInter) is prepared equal to (1, 3).

[197] The CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 21

[198] If the upper neighbor is CIIP encoded, (wIntra, wInter) of the current block is prepared equal to (wIntra, wInter) of the upper neighbor; otherwise, (wIntra, wInter) is prepared equal to (2, 2).

[199] The CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 22

[200] If the left or upper neighbor is/are CIIP-encoded, (wIntra, wInter) of the current block is set equal to (wIntra, wInter) of the first CIIP-encoded neighbor (left->upper); otherwise, (wIntra, wInter) is set equal to (1, 3).

[201] The CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 23

[202] If the left or upper neighbor is/are CIIP-encoded, (wIntra, wInter) of the current block is set equal to (wIntra, wInter) of the first CIIP-encoded neighbor (left->upper); otherwise, (wIntra, wInter) is set equal to (2, 2).

[203] The CIIP prediction is formed as follows: PCIIP = (winter * Pinter + wIntra * Pintra + 2) » 2 Mode 24 8.5.6 Decoding process for interblocks 8.5.6.1 General

[204] This process is invoked by decoding a coding unit encoded in the interprediction mode.

[205] When ciip_flag[xCb][yCb] is equal to 1, the array predSamples of prediction samples is modified as follows: - If cIdx is equal to 0, the following applies: - The general intraprediction sampling process as specified in clause 8.4.5.2.5 is invoked with the location (xTbCmp, yTbCmp) prepared equal to (xCb, yCb), the intraprediction mode predModeIntra prepared equal to IntraPredModeY[xCb][yCb], the transform block width nTbW and height nTbH prepared equal to cbWidth and cbHeight, the coding block width nCbW and height nCbH prepared equal to cbWidth and cbHeight, and the variable cIdx as inputs, and the output is assigned to the array (cbWidth)x (cbHeight) predSamplesIntraL. - The weighted sample prediction process for combined blend and intraprediction as specified in clause 8.5.6.7 is called with the location (xTbCmp, yTbCmp) prepared equal to (xCb, yCb), the coding block width cbWidth, the coding block height cbHeight, the sample matrices predSamplesInter and predSamplesIntra prepared equal to predSamples and predSamplesIntraL respectively, the intraprediction mode predModeIntra prepared equal to IntraPredModeY[ xCb ][ yCb ] and the color component index cIdx as inputs and the output is assigned to the array predSamples (cbWidth)x(cbHeight). … 8.5.6.7 Weighted sample prediction process for combined blend and intraprediction

[206] The inputs to this process are: - a luma location ( xCb, yCb ) specifying the top left sample of the current luma coding block relative to the top left luma sample of the current image, - the width of the current coding block cbWidth, - the height of the current coding block cbHeight, - two (cbWidth) x (cbHeight) arrays predSamplesInter and predSamplesIntra, - a cIdx variable specifying the index of the color component.

[207] The output of this process is the (cbWidth) x (cbHeight) predSamplesComb array of prediction sample values.

[208] The bitDepth variable is derived as follows: - If cIdx is equal to 0, bitDepth is set equal to BitDepthY. - Otherwise, bitDepth is set equal to BitDepthC.

[209] The variable scallFact is derived as follows: scallFact = ( cIdx = = 0 ) ? 0 : 1. (8-838)

[210] The neighboring luma locations (xNbA, yNbA) and (xNbB, yNbB) are prepared as equal to ( xCb - 1, yCb - 1 + ( cbHeight << scallFact ) ) and ( xCb - 1 + (cbWidth << scallFact ), yCb - 1 ), respectively.

[211] For X being replaced by either A or B, the variables availableX and isIntraCodedNeighbourX are derived as follows: - The availability derivation process for a neighbour block as specified in clause 6.4.4 is invoked with location (xCurr, yCurr) set equal to (xCb, yCb) and neighbour location (xNbY, yNbY) set equal to (xNbX, yNbX), checkPredModeY set equal to FALSE, and cldx set equal to 0 as inputs, and the output is assigned to availableX. - The variable isIntraCodedNeighbourX is derived as follows: - If availableX is equal to TRUE and CuPredMode[0][xNbX][yNbX] is equal to MODE_INTRA and BdpcmFlag[xNbX][yNbX] is equal to 0, then isIntraCodedNeighbourX is set equal to TRUE. - Otherwise, isIntraCodedNeighbourX is set equal to FALSE. The variable w is derived as follows: - If isIntraCodedNeighbourA and isIntraCodedNeighbourB are both equal to TRUE, then w is set equal to 3. - Otherwise, if isIntraCodedNeighbourA and isIntraCodedNeighbourB are both equal to FALSE, then w is set equal to 1. - Otherwise, w is set equal to 2.

[212] When cIdx is equal to 0 and slice_lmcs_enabled_flag is equal to 1, predSamplesInter[x][y] with x = 0..cbWidth - 1 and y = 0..cbHeight - 1 are modified as follows:

[213] FIG. 18 is a block diagram of a video processing apparatus 1800. The apparatus 1800 may be used to implement one or more of the methods described herein. The apparatus 1800 may be incorporated into a smartphone, tablet, computer, Internet of Things (IoT) receiver, and so on. The apparatus 1800 may include one or more processors 1802, one or more memories 1804, and video processing hardware 1806. The processor(s) 1802 may be configured to implement one or more methods described herein. The memory(ies) 1804 may be used to store data and code used to implement the methods and techniques described herein. The video processing hardware 1806 may be used to implement, in hardware circuitry, some of the techniques described herein.

[214] FIG. 20 is a flowchart for a method 2000 of processing a video. The method 2000 includes determining (2005) a coded mode of a first video block, constraining (2110) one or more flags to an operational state based on the determination of the coded mode of the first video block, the operational state being false or true; and performing (2015) further processing of a second video block according to the operational state of the one or more flags, wherein the first video block is a neighboring video block or a reference video block with respect to the second video block.

[215] FIG. 21 is a flowchart for a method 2100 of processing a video. The method 2100 includes determining (2105) whether pairwise prediction or bicombined prediction is used with respect to a first block of video, determining (2110) a combined intra- and inter-prediction (CIIP) operational state based on the determination that pairwise prediction or bicombined prediction is used, wherein the operational state is enabled or disabled, and performing further processing (2115) of the first block of video in accordance with the CIIP operational state.

[216] FIG. 23 is a flowchart for a method 2300 of processing a video. The method 2300 includes determining (2305), during a conversion between a first block in video data and a bitstream representation of the first block, one or more coded modes of one or more second blocks; determining (2310), based on the one or more coded modes of one or more second blocks, a coded mode constraint of the first block; performing (2315), at least by applying the coded mode constraint of the first block, the conversion; wherein the one or more second blocks comprise at least one of an adjacent block, a non-adjacent block, and a reference block of the first block.

[217] FIG. 24 is a flowchart for a method 2400 of processing a video. The method 2400 includes performing (2405) a conversion between a current block in video data and a bitstream representation of the current block using at least one of a combined intra-intra prediction (CIIP), a diffusion filtering, a bilateral filtering, a transform domain filtering, or another type of post-reconstruction filtering that is different from diffusion filtering, the bilateral filtering, and the transform domain filtering, wherein reconstructed neighboring samples of the current block used in at least one of the combined inter-intra prediction (CIIP), the diffusion filtering, the bilateral filtering, the transform domain filtering, or the other type of post-reconstruction filtering are replaced with approximated samples generated from the corresponding samples of the reconstructed neighboring samples in one or more reference pictures.

[218] FIG. 25 is a flowchart for a method 2500 of processing a video. The method 2500 includes storing (2505) a combined intra-interprediction (CIIP) and/or intra-mode CIIP mode flag with motion information in a history-based motion vector prediction (HMVP) table; and performing, at least based on the HMVP table, a conversion between a current block in video data and a bitstream representation of the current block.

[219] FIG. 26 is a flowchart for a method 2600 of processing a video. The method 2600 includes determining (2605), during a conversion between a current block in video data and a bitstream representation of the current block, a prediction mode for the current block; determining (2610) the applicability of a combined intra-inter-prediction (CIIP) mode by indicating that the CIIP mode is enabled for the current block in response to determining that the current block is encoded with an advanced motion vector prediction (AMVP) mode or a blending mode; and performing (2615), based on the applicability of the CIIP mode, the conversion.

[220] FIG. 27 is a flowchart for a method 2700 of processing a video. The method 2700 includes determining (2705), during a conversion between a current block in video data and a bitstream representation of the current block, a type of a selected blend candidate for the current block; determining (2710) the applicability of combined intra and inter prediction (CIIP) for the current block according to the selected blend candidate type, wherein the current block is encoded in blend mode.

[221] FIG. 28 is a flowchart for a method 2800 of processing a video. The method 2800 includes encoding (2805), during a conversion between a current video block in video data and a bitstream representation of the current video block, a combined intra- and inter-prediction (CIIP) flag for the current video block by a context-based coding model without reference to a CIIP flag of one or more video blocks neighboring the current video block; and performing (2810), at least by applying the combined intra- and inter-prediction (CIIP) flag of the current video block, the conversion.

[222] FIG. 29 is a flowchart for a method 2900 of processing a video. The method 2900 includes encoding (2905), during a conversion between a current video block in video data and a bitstream representation of the current video block, a combined intra and inter prediction (CIIP) flag for the current video block by a bias encoding; and performing (2910), at least by applying the combined intra and inter prediction (CIIP) flag, the conversion.

[223] FIG. 30 is a flowchart for a method 3000 of processing a video. The method 3000 includes determining (3005) an intraprediction mode of a first video block of a video according to a rule, the rule comprising: skipping, during an intraprediction mode derivation process of the first video block, checking the combined intra and intraprediction (CIIP) flag of one or more video blocks neighboring the first video block; and performing (3010), based on the at least one determined intraprediction mode, a conversion between the first video block and a bitstream representation of the first video block.

[224] FIG. 31 is a flowchart for a method 3100 of processing a video. The method 3100 includes determining (3105), during a conversion between a current video block, which is encoded in a combined intra- and inter-prediction (CIIP) mode, of a video and a bitstream representation of the current video block, a pair of weights comprising a first weighting for a first prediction result of the current video block and a second weighting for a second prediction result of the current video block, based on one or more video blocks neighboring the current video block, wherein the first prediction result is generated by an intra-prediction mode and the second prediction result is generated by an inter-prediction mode; and determining (3110) a prediction result of the current block based on a weighted sum of the first prediction result and the second prediction result.

[225] With reference to methods 2000 and 2100, some examples of combined intra- and inter-prediction for coding and their use are described in Section 4 of this document. For example, as described in Section 4, video blocks may be processed using according to a combined intra- and inter-prediction.

[226] Referring to methods 2000 and 2100, a video block may be encoded into the video bitstream where bit efficiency may be achieved using a bitstream generation rule related to combined intra and inter prediction.

[227] The methods may include wherein one or more flags include a combined intra and inter prediction (CIIP) flag, a local illumination compensation (LIC) flag, a diffusion filtering flag, a bilateral filtering flag, a transform domain filter flag, or another type of post-reconstruction filter flag.

[228] The methods may include wherein one or more flags include a first flag related to a first operation, the first flag is derived to be false, and the first operation is not applied.

[229] Methods may include where the use of the first operation is signaled to be skipped.

[230] Methods may include wherein the use of the first operation is flagged to be restricted to be false in a conforming bitstream.

[231] The methods may include wherein the first video block is within a neighboring row or column relative to the second video block.

[232] Methods may include where the neighboring line includes a line above or a line above to the right.

[233] Methods may include where the neighboring column includes a column to the left, a column below the left, or a corner column above the left.

[234] The methods may include wherein the encoded mode includes intramode, CIIP mode, or CPR mode.

[235] The methods may include determining a position of the second video block and wherein constraining one or more flags to the false state is also based on determining the position of the second video block.

[236] Methods may include wherein the position is at the top of a current coding tree unit (CTU) and a neighboring block above the second video block is within a different CTU.

[237] Methods may include wherein the position is on the left side of a current coding tree unit (CTU) and a left neighboring block of the second video block is within a different CTU.

[238] The methods may include wherein the one or more flags include a CIIP flag or an intra-mode CIIP mode flag and data related to the one or more flags is stored with motion information in a history-based motion vector prediction (HMVP) table.

[239] The methods may include comparing motion information of two candidates, and wherein the CIIP flag or the intra-mode CIIP mode flag is not used in comparing the motion information.

[240] The methods may include comparing motion information of two candidates, and wherein the CIIP flag or the intra-mode CIIP mode flag is used in comparing the motion information.

[241] The methods may include determining that a merge candidate is from an entry in the HMVP table; and copying a CIIP flag from the entry to the merge candidate.

[242] The methods may include determining that a merge candidate is from an entry in the HMVP table; and copying a CIIP flag and an intramode from the entry to the merge candidate.

[243] The methods may include wherein a flag of one or more flags is related to the CIIP and the CIIP is performed for advanced motion vector prediction (AMVP).

[244] Methods may include wherein a CIIP flag and an intra mode flag are signaled for AMVP mode.

[245] Methods may include where a CIIP flag is inherited in merge mode or UMVE mode, the CIIP flag includes a true operational state, more than one intramode is allowed in the CIIP, and an intramode is signaled based on more than one intramode being allowed in the CIIP.

[246] Methods may include wherein a CIIP flag and an intramode of neighboring or non-adjacent video blocks in blend mode or UMVE mode are inherited by the second video block.

[247] Methods may include wherein the CIIP is disabled for hopping mode.

[248] The methods may include comparing information related to two candidates, and wherein the CIIP flag or the intra CIIP mode flag is not used in comparing the information.

[249] The methods may include comparing information related to two candidates, and wherein the CIIP flag or the intra-mode CIIP mode flag is used in comparing the information.

[250] The methods may include wherein one or more candidates involved in the pairwise prediction or bicombined prediction adopt the CIIP prediction and wherein the operational state is activated.

[251] Methods may include where the intramode of one of the two candidates is inherited.

[252] Methods may include where the intramode is signaled.

[253] Methods may include where two candidates are involved in pairwise prediction or bicombined prediction.

[254] Methods may include wherein reconstructed samples used in CIIP mode, a diffusion filter, a bilateral filter, a transform domain filter, or other types of post-reconstruction filters are replaced with samples in reference images.

[255] The methods may include wherein the second video block is bipredicted and neighboring samples from two reference blocks are averaged to generate final neighboring samples.

[256] The methods may include wherein the second video block is bipredicted and neighboring samples from two reference blocks are used as final neighboring samples.

[257] The methods may include wherein the second video block is bipredicted and neighboring samples from two reference blocks are averaged weighted to generate final neighboring samples based on generalized unequal weighted biprediction (GBI) or LIC weighted prediction are applied to the second video block.

[258] The methods may include wherein samples in reference images are identified by motion information from the second video block.

[259] The methods may include wherein samples in reference images are identified by motion information from the second video block.

[260] Methods may include wherein a motion vector is rounded to integer precision and used to identify samples.

[261] The methods may include wherein the samples are in reference images that are identified by motion vectors in integer precision pel.

[262] The methods may include determining characteristics of the second video block, the characteristics including one or more of a block size, a slice type, an image type, a tile type, or motion information, and wherein the constraint of the operational state is based on the determination of the characteristics.

[263] The methods may include wherein the methods are signaled in a sequence parameter set (SPS), a video parameter set (VPS), a picture parameter set (PPS), a sequence header, a picture header, a slice header, a tile group header, a tile, or a group of CTUs.

[264] The following list of solutions additionally provides embodiments and variations for the items listed in the previous section (e.g., items 11 through 16).

[265] 40. A video processing method comprising: performing a conversion between a video block of a video and an encoded representation of the video block using a combined intra- and inter-prediction mode wherein the encoded representation corresponds to a weighted average of intra- and inter-prediction results of the video block using a pair of weights from a set of weight pairs in which less than three pairs are included.

[266] 41. The solution method 40, in which the set of weight pairs corresponds to two pairs.

[267] 42. The method of any of solutions 40-41, in which the weight pairs are determined based on a single neighboring block.

[268] 43. The method of any of solutions 40-41, in which the weight pairs are determined based on several neighboring blocks.

[269] 44. The method of solution 40, in which the set of weight pairs includes exactly one pair.

[270] 45. The method of solution 44, where the pair is one of (1,3) or (2, 2) or (1,7) or (2, 6) or (3, 5) or (4, 4).

[271] 46. A video processing method comprising: performing a conversion between a video block of a video and an encoded representation of the video block using a combined intra- and inter-prediction mode wherein the encoded representation corresponds to a weighted average of intra- and inter-prediction results of the video block using a pair of weights from a set of pairs of weights determined due to the encoding information of one or more neighboring blocks.

[272] 47. The solution method 46, in which the set of weight pairs is determined due to exactly one neighboring block.

[273] 48. The solution method 46, in which the set of weight pairs is determined due to two or more neighboring blocks.

[274] 49. The method of any of solutions 40 to 48, wherein the conversion includes encoding the video to generate the encoded representation.

[275] 50. The method of any of solutions 40-48, wherein the conversion includes decoding the encoded representation to generate the video.

[276] Several other modalities and additional features of these methods can be described using the following clause-based recitation.

[277] 1. A method for video processing, comprising: determining, during a conversion between a first block in video data and a bitstream representation of the first block, one or more coded modes of one or more second blocks; determining, based on the one or more coded modes of one or more second blocks, a coded mode constraint of the first block; and performing, at least by applying the coded mode constraint of the first block, the conversion; wherein the one or more second blocks comprise at least one of an adjacent block, a non-adjacent block, and a reference block of the first block.

[278] 2. The method of clause 1, wherein determining a coded mode restriction of the first block comprises: determining, based on one or more coded modes of one or more second blocks, one or more flags that correspond to one or more coded modes of the first block, respectively.

[279] 3. The method of clause 2, wherein the one or more coded modes comprise: a combined intra- and inter-prediction (CIIP) mode, a local illumination compensation (LIC) mode, a diffusion filtering mode, a bilateral filtering mode, a transform domain filtering mode, or a post-reconstruction filtering mode that is different from the diffusion filtering mode, the bilateral filtering mode, and the transform domain filtering mode.

[280] 4. The method of any of clauses 2-3, wherein the first block coded mode restriction comprises: a first coded mode among one or more coded modes of the first block is disabled, when a first flag corresponding to the first coded mode is derived to be false.

[281] 5. The method of any one of clauses 2-4, wherein the coded mode restriction of the first block comprises: information indicating whether a second coded mode among the one or more coded modes of the first block is enabled is not flagged, when a second flag corresponding to the second coded mode is derived to be false.

[282] 6. The method of any one of clauses 2-5, wherein the first block coded mode restriction comprises: information indicating whether a third coded mode among the one or more coded modes of the first block is enabled is flagged and restricted to be false in a compliance bitstream, when a third flag corresponding to the third coded mode is derived to be false.

[283] 7. The method of any one of clauses 1 through 6 further comprising: determining whether the coded mode restriction of the first block should be applied.

[284] 8. The method of clause 7, wherein determining whether to apply the coded mode restriction of the first block comprises: determining whether to apply the coded mode restriction of the first block according to the coded modes of neighboring rows or columns of the first block.

[285] 9. The method of clause 7, wherein determining whether to apply the first block coded mode restriction comprises: determining whether to apply the first block coded mode restriction according to at least N samples in neighboring rows or neighboring columns of the first block that are not coded with a fourth mode, and N>1.

[286] 10. The method of clause 8 or 9, in which the neighbouring line comprises one line above and one line above to the right of the first block.

[287] 11. The method of any of clauses 8 to 10, wherein the neighbouring column comprises a column to the left, a column below the left and a corner column above the left of the first block.

[288] 12. The method of any one of clauses 7 through 11, wherein determining whether the first block coded mode restriction should be applied comprises: determining whether the first block coded mode restriction should be applied when any non-adjacent neighboring block is coded with a fourth mode.

[289] 13. The method of any one of clauses 7 through 11, wherein determining whether the first block coded mode restriction should be applied comprises: determining whether the first block coded mode restriction should be applied when all neighboring non-adjacent blocks are coded with a fourth mode.

[290] 14. The method of any one of clauses 7 through 11, wherein determining whether the first block coded mode restriction should be applied comprises: determining the first block coded mode restriction should not be applied when at least M non-adjacent neighboring blocks are not coded with a fourth mode, and M is a first predefined threshold.

[291] 15. The method of any one of clauses 9 to 14, wherein the fourth encoded mode comprises at least one of an intra-prediction mode, a combined intra- and inter-prediction (CIIP) mode, and a current image reference (CPR) mode.

[292] 16. The method of any one of clauses 7 to 14, wherein determining whether to apply the first block coded mode restriction comprises: determining whether to apply the first block coded mode restriction according to a position of the first block.

[293] 17. The method of clause 16, wherein determining whether the first block coded mode restriction should be applied according to a position of the first block comprises: determining the first block coded mode restriction should not be applied when the position is at the top of a current coding tree unit (CTU) and a neighboring block above and the first block belong to different CTUs.

[294] 18. The method of clause 16, wherein determining whether the first block coded mode restriction should be applied according to a position of the first block comprises: determining the first block coded mode restriction should not be applied when the position is to the left of a current coding tree unit (CTU) and a neighboring block to the left and the first block belong to different CTUs.

[295] 19. The method of any one of clauses 1 through 18 further comprising: determining the characteristic of the current block; and determining the application of the coded mode restriction of the current block when the characteristic of the current block satisfies a predefined condition.

[296] 20. The method of any one of clauses 1 to 18 further comprising: determining characteristics of the current block and/or previously encoded blocks; and determining whether to apply the coded mode restriction of the current block in accordance with the characteristics of the current block and/or previously encoded blocks.

[297] 21. A method for video processing, comprising: performing a conversion between a current block in video data and a bitstream representation of the current block using at least one of a combined intra- and inter-prediction (CIIP), a diffusion filtering, a bilateral filtering, a transform domain filtering, or another type of post-reconstruction filtering that is different from the diffusion filtering, the bilateral filtering, and the transform domain filtering, wherein reconstructed neighboring samples of the current block used in at least one of the combined intra- and inter-prediction (CIIP), the diffusion filtering, the bilateral filtering, the transform domain filtering, or the other type of post-reconstruction filtering are replaced by approximated samples generated from the corresponding samples of the reconstructed neighboring samples in one or more reference pictures.

[298] 22. The method of clause 21, wherein neighboring samples from two reference blocks of the current block are averaged to generate the approximate samples when the current block is bipredicted.

[299] 23. The method of clause 21, wherein neighboring samples of a reference block of the current block are used as the approximate samples when the current block is bi-predicted or uni-predicted.

[300] 24. The method of clause 21, wherein neighboring samples from two reference blocks of the current block are averaged to generate the approximated samples when the current block is bipredicted and at least one of a generalized unequal-weighted biprediction (GBI), a weighted prediction, and a local illumination compensation (LIC) are applied to the current block.

[301] 25. The method of clauses 22 to 24, wherein neighboring samples of reference blocks of the current block are identified by motion information of the current block.

[302] 26. The method of clauses 22 to 24, wherein neighboring samples of reference blocks of the current block are identified by modified motion information of the current block.

[303] 27. The method of clause 24, wherein the modified motion information of the current block is a modified motion vector that is rounded to integer precision.

[304] 28. The method of clause 21, wherein neighboring samples of the reference blocks of the current block are identified by motion vectors with integer precision pel.

[305] 29. The method of clause 28, wherein the motion vectors of the reconstructed neighboring samples are rounded to integer precision so as to identify the corresponding samples.

[306] 30. The method of any one of clauses 21 through 29, wherein the reconstructed neighboring samples of the current block are replaced by the approximated samples only when the current block is encoded with integer precision pel.

[307] 31. The method of any one of clauses 21 through 30, wherein reconstructed neighboring samples of the current block are replaced by the approximated samples for the luma component or chroma component only.

[308] 32. The method of any one of clauses 19 to 31 further comprising: determining the characteristic of the current block; and determining the replacement of the reconstructed neighboring samples by the approximated samples when the characteristic of the current block satisfies a predefined condition.

[309] 33. The method of clause 19 or 32, wherein the current block feature comprises at least one of a block size, a slice type, an image type, a tile type, and motion information.

[310] 34. The method of clause 33, where the predefined condition is that the current block contains samples no smaller than a second predefined threshold.

[311] 35. The method of clause 33, where the predefined condition is that a width and a height of the current block are greater than a third predefined threshold.

[312] 36. The method of clause 33, where the predefined condition is that a width and a height of the current block are less than a fourth predefined threshold.

[313] 37. The method of clause 33, where the predefined condition is that a width of the current block is less than a fifth predefined threshold and/or a height of the current block is less than a sixth predefined threshold.

[314] 38. The method of clause 33, where the predefined condition is that a width of the current block is greater than a seventh predefined threshold and/or a height of the current block is greater than an eighth predefined threshold.

[315] 39. The method of clause 38, wherein information indicating whether to apply the coded mode constraint of the current block and/or replace the reconstructed neighboring samples with the approximated samples in a sequence parameter set (SPS), a view parameter set (VPS), an image parameter set (PPS), a sequence header, an image header, a slice header, a tile group header, a tile, or a group of CTUs is signaled.

[316] 40. The method of any one of clauses 21 to 39 further comprising: determining characteristics of the current block and/or previously coded blocks; and determining whether the reconstructed neighboring samples should be replaced by the approximated samples according to the characteristics of the current block and/or previously coded blocks.

[317] 41. The method of clause 20 or 40, wherein the characteristics of the current block and/or previously encoded blocks comprise at least one of a block dimension, a video data processing unit (VPDU), a picture type, a low delay check flag, encoded information of the current block and/or previously encoded blocks.

[318] 42. The method of clause 41, wherein the coded information of the current block and/or previously coded blocks indicates reference pictures, a uni-prediction or a bi-prediction.

[319] 43. A video processing apparatus comprising a processor configured to implement a method recited in any one or more of clauses 1 to 42.

[320] 44. The apparatus of clause 43, where the apparatus is a video encoder.

[321] 45. The apparatus of clause 43, where the apparatus is a video set-top box.

[322] 46. A computer-readable recoding medium on which a program comprising code is recorded, the program being for a processor to perform a method recited in any one of clauses 1 to 42.

[323] Several other modalities and additional features of these methods can be described using the following clause-based recitation.

[324] 1. A method for video processing, comprising: storing a combined intra and inter prediction (CIIP) flag and/or intra mode of the CIIP mode with motion information in a history-based motion vector prediction (HMVP) table; and performing, at least based on the HMVP table, a conversion between a current block in video data and a bitstream representation of the current block.

[325] 2. The method of clause 1 further comprising: comparing motion information of two candidates, wherein the CIIP flag and/or the CIIP mode intramode are not used in comparing the motion information of two candidates.

[326] 3. The method of clause 1 further comprising: comparing motion information of two candidates, wherein the CIIP flag and/or the intramode of the CIIP mode are used in comparing the motion information of two candidates.

[327] 4. The method of any one of clauses 1 through 3, wherein the performance comprises: when a merge candidate is an entry in the HMVP table, copying the CIIP flag from the entry to the merge candidate.

[328] 5. The method of any one of clauses 1 through 3, wherein the performance comprises: when a merge candidate is an entry in the HMVP table, copying the CIIP flag and the intramode from the entry to the merge candidate.

[329] 6. A method for video processing, comprising: determining, during a conversion between a current block in video data and a bitstream representation of the current block, a prediction mode for the current block; determining the applicability of a combined intra- and inter-prediction (CIIP) mode by indicating that the CIIP mode is enabled for the current block in response to determining that the current block is encoded with an advanced motion vector prediction (AMVP) mode or a blending mode; and performing, based on the applicability of the CIIP mode, the conversion.

[330] 7. The method of clause 6, wherein a CIIP and/or CIIP mode intramode flag is signaled when the current block is encoded with AMVP mode.

[331] 8. The method of clause 6 or 7, wherein a CIIP and/or intramode CIIP mode flag of adjacent neighboring blocks and/or non-adjacent neighboring blocks are inherited into a blend mode and/or a blend with motion vector difference (MMVD) mode of the current block.

[332] 9. The method of any of clauses 6 through 8, wherein a CIIP and/or intra-mode CIIP mode flag for a non-skip merge mode and/or a non-skip MMVD mode is signaled, and the CIIP and/or intra-mode CIIP mode flag of adjacent neighboring blocks and/or non-adjacent neighboring blocks are inherited into a skip merge mode and/or a skip MMVD mode.

[333] 10. The method of any one of clauses 6 through 8, wherein a CIIP and/or intra-mode CIIP mode flag for a skip merge mode and/or a skip MMVD mode is signaled, and the CIIP and/or intra-mode CIIP mode flag of adjacent neighboring blocks and/or non-adjacent neighboring blocks is inherited into a non-skip merge mode and/or a non-skip MMVD mode.

[334] 11. The method of any of clauses 6 through 10, wherein the CIIP flag is inherited in a merge mode and/or an MMVD skip mode.

[335] 12. The method of clause 11, where the intramode is signaled when the CIIP flag is true and more than one intramode is allowed in CIIP mode.

[336] 13. The method of any one of clauses 6 through 12, wherein a CIIP and/or intramode CIIP mode flag of adjacent neighboring blocks and/or non-adjacent neighboring blocks encoded in a merge mode and/or an MMVD mode are inherited by the current block.

[337] 14. The method of any one of clauses 6 through 13 further comprising: disabling the CIIP mode to a jump mode.

[338] 15. The method of any one of clauses 6 to 13 further comprising: comparing information of two merge candidates, wherein the CIIP flag and/or the intramode of the CIIP mode are used in comparing the information of two merge candidates.

[339] 16. The method of any one of clauses 6 to 13 further comprising:

[340] comparing information from two merge candidates, wherein the CIIP flag and/or the CIIP mode intramode are used in comparing the information from two merge candidates.

[341] 17. A method for video processing, comprising: determining, during a conversion between a current block in video data and a bitstream representation of the current block, a type of a selected blend candidate for the current block, and determining the applicability of combined intra and inter prediction (CIIP) for the current block according to the selected blend candidate type, wherein the current block is encoded in blend mode.

[342] 18. The method of clause 17, wherein the CIIP is disabled when the merge candidate selected from the current block is at least one of a pairwise merge candidate, a bicombined merge candidate, a zero-movement merge candidate, or a virtual or artificial merge candidate.

[343] 19. The method of clause 17 or 18, wherein when a candidate involved in a pairwise merge candidate or the bicombined merge candidate adopts the CIIP mode, the CIIP mode is activated for the pairwise merge candidate or the bicombined merge candidate.

[344] 20. The method of clause 19, where an intramode of the CIIP mode candidate involved is inherited.

[345] 21. The method of clause 19, wherein an intramode of the involved CIIP mode is signaled to the pairwise merge candidate or the bicombined merge candidate.

[346] 22. The method of clause 17 or 18, wherein when both candidates involved in a pairwise merge candidate or a bicombined merge candidate adopt the CIIP mode, the CIIP mode is activated for the pairwise merge candidate or the bicombined merge candidate.

[347] 23. The method of clause 22, in which an intramode of one of the two candidates involved is inherited.

[348] 24. The method of clause 22, wherein an intramode of the CIIP mode involved is derived from the intramodes of the two candidates involved and is used for the pairwise blend candidate or the bicombined blend candidate.

[349] 25. The method of clause 22, wherein an intramode of the involved CIIP mode is signaled to the pairwise merge candidate or the bicombined merge candidate.

[350] 26. A video processing apparatus comprising a processor configured to implement a method recited in any one or more of clauses 1 to 25.

[351] 27. The apparatus of clause 26, wherein the apparatus is a video encoder.

[352] 28. The apparatus of clause 26, wherein the apparatus is a video set-top box.

[353] 29. A computer-readable recoding medium on which a program comprising code is recorded, the program being for a processor to perform a method recited in any one of clauses 1 to 25.

[354] Several other modalities and additional features of these methods can be described using the following clause-based recitation.

[355] 1. A method for video processing, comprising: encoding, during a conversion between a current video block in video data and a bitstream representation of the current video block, a combined intra- and inter-prediction (CIIP) flag for the current video block by a context-based coding model without reference to a CIIP flag of one or more video blocks neighboring the current video block, and performing, at least by applying the combined intra- and inter-prediction (CIIP) flag of the current video block, the conversion.

[356] 2. The method of clause 1, wherein a fixed context is used in encoding based on the context model of the CIIP flag of the current video block.

[357] 3. A method for video processing, comprising: encoding, during a conversion between a current video block in video data and a bitstream representation of the current video block, a combined intra and inter prediction (CIIP) flag for the current video block by a bypass encoding, and performing, at least by applying the combined intra and inter prediction (CIIP) flag, the conversion.

[358] 4. The method of clause 3, wherein encoding a combined intra and inter prediction (CIIP) flag for the current video block by a bias encoding comprises encoding the CIIP flag with equal probabilities of being equal to 0 and 1.

[359] 5. The method of any one of clauses 1 to 4 further comprising: in response to the current video block being encoded with the CIIP mode, preparing an intraprediction mode associated with the current video block for a given intraprediction mode.

[360] 6. The method of clause 5, wherein the given intraprediction mode is a planar mode.

[361] 7. The method of clause 5 or 6, wherein the given intraprediction mode is used for a process of determining the intraprediction mode of subsequent coded video blocks.

[362] 8. The method of clause 7 further comprising: during a conversion of a second video block that is one of the subsequent coded video blocks of the current video block, if the current video block is a neighboring video block of the second video block, the provided intraprediction mode is added to an intraprediction mode candidate list of the second video block.

[363] 9. The method of clause 8 further comprising: the intraprediction mode candidate list includes a most likely mode candidate list.

[364] 10. The method of any one of clauses 1 through 9, wherein in response to the current video block being encoded with a CIIP mode, the intraprediction mode information of the current video block is not stored.

[365] 11. The method of clause 10, wherein the current video block is considered to be unavailable in a process of decoding other blocks.

[366] 12. The method of clause 10, wherein the current video block is considered to be a video block encoded with an interprediction mode.

[367] 13. The method of clauses 1 through 12, wherein the CIIP flag of the current video block is not stored.

[368] 14. A method for video processing, comprising: determining an intraprediction mode of a first video block of a video according to a rule, and the rule comprising: skipping, during an intraprediction mode derivation process of the first video block, checking the combined intra and interprediction (CIIP) flag of one or more video blocks neighboring the first video block, and performing, based on the at least one determined intraprediction mode, a conversion between the first video block and a bitstream representation of the first video block.

[369] 15. The method of clause 14, wherein determining an intraprediction mode comprises determining a most likely mode.

[370] 16. The method of clause 14 or 15, wherein for a second video block of the video, in response to the second video block being encoded or CIIP encoded, a default intraprediction mode is prepared for the second video block, wherein the second video block is a neighboring video block of the first video block.

[371] 17. The method of clause 16, wherein the determination of an intraprediction mode is based on the default intraprediction mode of the second video block; and the default intraprediction mode is the planar intraprediction mode.

[372] 18. The method of any one of clauses 14 through 17, wherein the CIIP flag of one or more neighboring video blocks is not stored.

[373] 19. A video processing apparatus comprising a processor configured to implement a method recited in any one or more of clauses 1 to 18.

[374] 20. The apparatus of clause 19, wherein the apparatus is a video encoder.

[375] 21. The apparatus of clause 19, wherein the apparatus is a video set-top box.

[376] 22. A computer-readable recoding medium on which a program comprising code is recorded, the program being for a processor to perform a method recited in any one of clauses 1 to 21.

[377] Several other modalities and additional features of these methods can be described using the following clause-based recitation.

[378] 1. A method for video processing, comprising: determining, during a conversion between a current video block, which is encoded in a combined intra- and inter-prediction (CIIP) mode, of a video and a bitstream representation of the current video block, a pair of weights comprising a first weighting for a first prediction result of the current video block and a second weighting for a second prediction result of the current video block, based on one or more video blocks neighboring the current video block, wherein the first prediction result is generated by an intra-prediction mode and the second prediction result is generated by an inter-prediction mode; and determining a prediction result of the current block based on a weighted sum of the first prediction result and the second prediction result.

[379] 2. The method of clause 1, wherein determining the weight pair comprises: determining the weight pair according to a prediction mode of one or more neighboring video blocks of the current video block.

[380] 3. The method of clause 1 or 2, wherein for a neighboring video block encoded with CIIP mode, the neighboring video block is treated as a block encoded with interprediction mode.

[381] 4. The method of clause 1 or 2, wherein for a neighboring video block encoded with CIIP mode, the neighboring video block is treated as a block encoded with intraprediction mode.

[382] 5. The method of any one of clauses 1 through 4, wherein the neighboring video blocks are at least one of an adjacent block, a non-adjacent block, and a temporal neighboring block of the current video block.

[383] 6. The method of any one of clauses 1 through 5, wherein one of the neighboring video blocks is a left neighboring video block or an upper neighboring video block.

[384] 7. The method of any one of clauses 1 through 5, wherein two of the neighboring video blocks are a left neighboring video block and an upper neighboring video block, respectively.

[385] 8. The method of clause 6 or 7, wherein the left neighboring video block covers a location (xCb-1, yCb cbHeight-1) and the top neighboring video block covers a location (xCb cbWidth-1, yCb-1), and wherein (xCb, yCb) is a location of a top left sample of the current video block and cbWidth and cbHeight are the width and height of the current video block, respectively.

[386] 9. The method of clause 6 or 7, wherein the left neighboring video block covers a location (xCb-1, yCb) and the upper neighboring video block covers a location (xCb, yCb-1), and wherein (xCb, yCb) is a location of an upper left sample of the current video block.

[387] 10. The method of any one of clauses 1 through 9, wherein a CIIP mode result is obtained by applying the weight pair to the intraprediction result and the interprediction result as: PCIIP = (winter * Pinter + wIntra * Pintra + offset) » N and where PCIIP is the CIIP mode result, Pinter is the interprediction result, Pintra is the intraprediction result, (winter, wIntra) is the weight pair, offset is prepared as (1 << (N-1)) or 0, and N is prepared as log2(wIntra+wInter).

[388] 11. The method of any one of clauses 1 through 10, wherein the neighboring video block is selected based on the coding information of the current block and/or the neighboring block.

[389] 12. The method of any one of clauses 1 through 11, wherein the weight pair is determined based on the coding information of the neighboring block and/or neighboring block.

[390] 13. The method of clause 11 or 12, wherein the coding information comprises at least one of: block dimension information, block shape information, low delay check flag, reference picture information, motion information of the current video block and/or neighboring video block, or intra-prediction modes of the neighboring video block.

[391] 14. The method of clause 1, wherein the conversion is performed based on the color component of the current video block.

[392] 15. The method of clause 14, wherein the weight pair for a major color component is different from those for other color components.

[393] 16. The method of clause 14, where the weight pair for a luma component is different from that for a chroma component.

[394] 17. The method of any of clauses 14 to 16, wherein the first weighting and the second weighting are equal for a chroma component.

[395] 18. The method of any one of clauses 1 to 17, wherein the weight pair is one of two candidate weight pairs comprising a first candidate weight pair and a second candidate weight pair.

[396] 19. The method of clause 18, where the two candidate weight pairs are one of {(1, 3) and (3, 1)}, {(1, 3) and (2, 2)}, {(3, 1) and (2, 2)}, {(3, 5) and (4, 4)}, {(5, 3) and (4, 4)}, {(1, 7) and (4, 4)}, and {(7, 1) and (4, 4)}.

[397] 20. The method of clause 18 or 19, wherein the weight pair is determined based on a single neighboring video block of the current video block.

[398] 21. The method of clause 20, wherein when the single neighboring video block is coded with the intra-prediction mode, the weight pair is the first candidate weight pair; and when the single neighboring video block is coded with the inter-prediction mode, the weight pair is the second candidate weight pair.

[399] 22. The method of clause 20 or 21, wherein the only neighboring video block is a left-neighboring video block or an up-neighboring video block.

[400] 23. The method of clause 18 or 19, wherein the weight pair is determined based on two or more neighboring video blocks of the current video block and at least one of the two or more neighboring video blocks satisfies predetermined conditions.

[401] 24. The method of clause 23, wherein when at least one of two or more neighboring video blocks is coded with the intra-prediction mode, the weight pair is the first candidate weight pair; and when at least one of two or more neighboring video blocks is coded with the inter-prediction mode, the weight pair is the second candidate weight pair.

[402] 25. The method of clause 18 or 19, wherein the weight pair is determined based on two or more neighboring video blocks of the current video block and each of the two or more neighboring video blocks satisfies predetermined conditions.

[403] 26. The method of clause 25, wherein when all two or more neighboring video blocks are coded with the intra-prediction mode, the weight pair is the first candidate weight pair; and when all two or more neighboring video blocks are coded with the inter-prediction mode, the weight pair is the second candidate weight pair.

[404] 27. The method of any one of clauses 23 through 26, wherein one of the two or more neighboring video blocks is a left-neighboring video block and the other of the two or more neighboring video blocks is an up-neighboring video block.

[405] 28. The method of any of clauses 23 through 27, wherein the first candidate weight pair is one of (2, 2) and (3, 1), and the second candidate weight pair is (1, 3).

[406] 29. The method of any of clauses 23 through 28, wherein at least one weighting value in the first candidate weight pair is different from at least one weighting value in the second candidate weight pair.

[407] 30. The method of any of clauses 23 through 29, wherein the first candidate weight pair is different from the second candidate weight pair.

[408] 31. The method of any of clauses 1 through 17, wherein the weight pair is exactly one candidate weight pair.

[409] 32. The method of clause 31, where the candidate weight pair is one of (1,3), (2,2), (1, 7), (2, 6), (3, 5), and (4, 4).

[410] 33. The method of any one of clauses 1 through 32, wherein the weight pair is determined based on whether one or more neighboring video blocks are encoded with the CIIP mode.

[411] 34. The method of clause 33, wherein the weight pair is determined from the weight pair for a previously encoded video block.

[412] 35. The method of clause 33 or 34, wherein the weight pair for the current video block is determined based on a single neighboring video block of the current video block.

[413] 36. The method of clause 35, wherein when the single neighboring video block is coded with the CIIP mode, the weight pair for the current video block is arranged to be the weight pair for the single neighboring video block; and when the single neighboring video block is coded with the intra-prediction mode, the weight pair is a first candidate weight pair of two candidate weight pairs comprising the first candidate weight pair and a second candidate weight pair; when the single neighboring video block is coded with the inter-prediction mode, the weight pair is the second candidate weight pair of two candidate weight pairs comprising the first candidate weight pair and the second candidate weight pair.

[414] 37. The method of clause 35, wherein when the single neighboring video block is coded with the CIIP mode, the weight pair for the current video block is arranged to be the weight pair for the single neighboring video block; and when the single neighboring video block is coded with the intra-prediction mode or the inter-prediction mode, the weight pair is a first candidate weight pair of two candidate weight pairs comprising the first candidate weight pair and a second candidate weight pair.

[415] 38. The method of clause 33 or 34, wherein the weight pair is determined based on two or more neighboring video blocks of the current video block and at least one of the two or more neighboring video blocks satisfies predetermined conditions.

[416] 39. The method of clause 38, wherein the two or more neighboring video blocks are checked in a certain checking order to identify whether the two or more neighboring video blocks are encoded with the CIIP mode.

[417] 40. The method of clause 39, wherein when at least one of the two or more neighboring video blocks is coded with the CIIP mode, the weight pair for the current video block is arranged to be the weight pair for the neighboring video block that is first identified to be coded with the CIIP mode in the given verification order; when none of the two or more neighboring video blocks is coded with the CIIP mode, at least one of the two or more neighboring video blocks is coded with the intra-prediction mode, the weight pair is a first candidate weight pair of two candidate weight pairs comprising the first candidate weight pair and a second candidate weight pair; when none of the two or more neighboring video blocks is coded with the CIIP mode, at least one of the two or more neighboring video blocks is coded with the inter-prediction mode, the weight pair is the second candidate weight pair of two candidate weight pairs comprising the first candidate weight pair and the second candidate weight pair.

[418] 41. The method of clause 39, wherein when at least one of two or more neighboring video blocks is coded with the CIIP mode, the weight pair for the current video block is arranged to be the weight pair for the neighboring video block that is first identified to be coded with the CIIP mode in the given verification order; when none of the two or more neighboring video blocks is coded with the CIIP mode, the weight pair is a second candidate weight pair of two candidate weight pairs comprising a first candidate weight pair and a second candidate weight pair.

[419] 42. The method of any of clauses 36 through 41, wherein the first candidate weight pair is one of (2, 2) and (3, 1), and the second candidate weight pair is (1, 3).

[420] 43. The method of any of clauses 36 through 42, wherein at least one weight value in the first candidate weight pair is different from at least one weight value in the second candidate weight pair.

[421] 44. The method of any of clauses 36 through 41, wherein the second candidate weight pair is one of (2, 2) and (1, 3).

[422] 45. The method of any of clauses 1 through 44, wherein the weight pair is signed.

[423] 46. The method of any one of clauses 1 through 45, wherein the weight pair is determined based on whether a neighboring video block is encoded with an interprediction mode.

[424] 47. The method of any one of clauses 1 through 46, wherein when a neighboring video block is not coded with an intraprediction mode, the neighboring video block is treated as a block coded with an intraprediction mode.

[425] 48. The method of clause 47, wherein the neighboring video block is not encoded with at least one of an intrablock copy (IBC) mode, a CIIP mode, a triangular prediction mode (TPM), a palette mode, an RDPCM mode.

[426] 49. The method of clause 48, wherein the neighboring video block is encoded without applying a transform and/or quantization.

[427] 50. The method of any one of clauses 1 through 46, wherein when the neighboring video block is encoded with at least one of an intrablock copy (IBC) mode, a CIIP mode, a triangular prediction mode (TPM), a palette mode, an RDPCM mode, the neighboring video block is treated as a block encoded with non-intraprediction mode.

[428] 51. The method of any one of clauses 1 through 46, wherein when the neighboring video block is coded with an intraprediction mode but is not coded with a predetermined prediction mode, the neighboring video block is treated as a block coded with a non-intraprediction mode.

[429] 52. The method of any one of clauses 1 through 46, wherein when the neighboring video block is coded in a matrix-based intraprediction mode and/or a multiple reference line intraprediction mode with reference line index other than 0 and/or a BDPCM mode, the neighboring video block is treated as a block coded with non-intraprediction mode.

[430] 53. A video processing apparatus comprising a processor configured to implement a method recited in any one or more of clauses 1 to 52.

[431] 54. The apparatus of clause 53, wherein the apparatus is a video encoder.

[432] 55. The apparatus of clause 53, where the apparatus is a video set-top box.

[433] 56. A computer-readable recoding medium on which a program comprising code is recorded, the program being for a processor to perform a method recited in any one of clauses 1 to 52.

[434] It will be appreciated that the disclosed techniques can be incorporated into video encoders or decoders to improve compression efficiency using hash-based motion estimation.

[435] The disclosed and other solutions, examples, embodiments, modules, and functional operations described herein may be implemented in digital electronic circuit assemblies, or in computer software, firmware, or hardware, including the structures disclosed herein and their structural equivalents, or in combinations of one or more thereof. The disclosed and other embodiments may be implemented as one or more computer program products, i.e., one or more modules of computer program instructions encoded on a computer-readable medium for execution by, or to control the operation of, data processing apparatus. The computer-readable medium may be a machine-readable storage device, a machine-readable storage substrate, a memory device, a composition of matter effecting a propagated machine-readable signal, or a combination of one or more thereof. The term “data processing apparatus” encompasses all apparatus, devices, and machines for processing data, including, by way of example, a programmable processor, a computer, or multiple processors or computers. The apparatus may include, in addition to the hardware, code that creates an execution environment for the computer program in question, for example, code constituting processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of these. A propagated signal is an artificially generated signal, for example, a machine-generated electrical, optical, or electromagnetic signal, that is generated to encode information for transmission to a suitable receiving apparatus.

[436] A computer program (also known as a program, software, software application, script, or code) may be written in any form of programming language, including compiled or interpreted languages, and may be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program may be stored in a portion of a file that contains other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, subprograms, or portions of code). A computer program may be deployed to run on one computer or on multiple computers that are co-located in one location or distributed across multiple locations and interconnected by a communications network.

[437] The processes and logic flows described herein may be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows may also be performed by, and the devices may also be implemented as, special purpose logic circuit assemblies, for example, an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).

[438] Processors suitable for executing a computer program include, by way of example, both general-purpose and special-purpose microprocessors and any one or more processors of any type of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random-access memory or both. The essential elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic disks, magneto-optical disks or optical disks. However, a computer need not have such devices. Computer-readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, memory media and devices, including by way of example, semiconductor memory devices, e.g., EPROM, EEPROM and flash memory devices; magnetic disks, for example, internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and memory may be supplemented by, or incorporated into, special-purpose logic circuit assemblies.

[439] While this patent document contains many specifics, these should not be construed as limitations on the scope of any subject matter or what may be claimed, but rather as descriptions of features that may be specific to particular embodiments of particular techniques. Certain features that are described in this patent document in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, multiple features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable subcombination. Furthermore, while features may be described above as acting in certain combinations and even initially claimed as such, one or more features of a claimed combination may in some cases be excised from the combination and the claimed combination may be directed to a subcombination or variation of a subcombination.

[440] Similarly, although operations are depicted in the figures in a particular order, this should not be construed as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. Furthermore, the separation of various system components in the embodiments described in this patent document should not be construed as requiring such separation in all embodiments.

[441] Only some implementations and examples are described and other implementations, improvements and variations can be made based on what is described and illustrated in this patent document.

Claims (15)

1. A method for video processing comprising: determining, during a conversion between a current video block, which is encoded in a combined intra- and inter-prediction mode, of video data and a bitstream, a pair of weights comprising a first weight for a first prediction result of the current video block and a second weight for a second prediction result of the current video block, based on one or more video blocks neighboring the current video block, wherein the first prediction result is generated by an intra-prediction mode and the second prediction result is generated by an inter-prediction mode; and determining a prediction result of the current block based on a weighted sum of the first prediction result and the second prediction result; and performing the conversion based on the prediction result, wherein the weight pair is determined according to a prediction mode of the one or more neighboring video blocks of the current video block, wherein when at least one neighboring video block of the one or more neighboring video blocks is coded with the combined intra- and inter-prediction mode, the at least one neighboring video block is treated as a video block coded with an inter-prediction mode that is a non-intra-prediction mode, wherein the one or more neighboring video blocks comprise a video block covering a location (xCb-1, yCb-1+(cbHeight<<a)) and a video block covering a location (xCb-1+(cbWidth<<a), yCb-1), wherein (xCb, yCb) is a location of an upper left sample of the current video block, cbWidth and cbHeight are the width and height of the current video block respectively, and a is determined using a cIdx of the block current, where cIdx is a variable specifying a color component index for the current block, and where the color component index of the current block indicates a color component of the current block is a luma component. 2. The method of claim 1, wherein the prediction mode of the one or more neighboring video blocks indicates whether the one or more neighboring video blocks are encoded with an intra-prediction mode or a non-intra-prediction mode. 3. The method of claim 1, wherein when the at least one neighboring video block is encoded with at least one of an intrablock copy mode, a combined intra- and inter-prediction mode, a geometric partitioning mode, or a palette mode, the at least one neighboring video block is treated as a block encoded with a non-intraprediction mode. 4. Method according to claim 1, characterized in that the weight pair is additionally determined according to a color component of the current video block. 5. The method of claim 4, wherein a location of the one or more neighboring video blocks is determined in the color component of the current block. 6. The method of claim 1, wherein the one or more neighboring video blocks comprise at least one of a left neighboring video block or an upper neighboring video block. 7. The method of claim 1, wherein the weight pair is determined according to whether the one or more neighboring video blocks are available, and wherein a checkPredModeY variable specifying whether the availability of the one or more neighboring video blocks depends on a prediction mode is set to false. 8. The method of claim 1, wherein in response to the cIdx of the current block being equal to 0, the value of a is set to 0. 9. The method of claim 1, wherein in response to the cIdx of the current block not being equal to 0, the value of a is set to 1. 10. The method of claim 1, wherein the weight pair is determined based on two or more neighboring video blocks; when all of the two or more neighboring video blocks are encoded with the intra-prediction mode, the weight pair is a first candidate weight pair; when all of the two or more neighboring video blocks are in the non-intra-prediction mode, the weight pair is a second candidate weight pair different from the first candidate weight pair; otherwise, the weight pair is a third candidate weight pair different from the first and second candidate weight pairs. 11. The method of claim 1, wherein the first candidate weight pair is (3, 1), the second candidate weight is (1, 3), and the third candidate weight pair is (2, 2), wherein for (x, y), x is the first weight and y is the second weight. 12. Method according to claim 1, characterized in that the prediction result is obtained by applying the pair of weights to the intra-prediction result and the inter-prediction result as: P = (winter * Ptnter + wIntra * Ptntra + offset') » N and wherein P is the prediction result, Pinter is the first prediction result, Pintra is the second prediction result, (wInter, wIntra) the pair of weights, offset is prepared as 2. 13. Apparatus for processing video data, comprising a processor and a non-transitory memory with instructions therein, wherein the instructions upon execution by the processor cause the processor to: determine, during a conversion between a current video block, which is encoded in a combined intra- and inter-prediction mode, of video data and a bitstream, a pair of weights comprising a first weight for a first prediction result of the current video block and a second weight for a second prediction result of the current video block, based on one or more video blocks neighboring the current video block, wherein the first prediction result is generated by an intra-prediction mode and the second prediction result is generated by an inter-prediction mode; determine a prediction result of the current block based on a weighted sum of the first prediction result and the second prediction result; and perform the conversion based on the prediction result wherein the weight pair is determined according to a prediction mode of the one or more neighboring video blocks of the current video block, wherein when at least one neighboring video block of the one or more neighboring video blocks is coded with the combined intra- and inter-prediction mode, the at least one neighboring video block is treated as a video block coded with an inter-prediction mode that is a non-intra-prediction mode, wherein the one or more neighboring video blocks comprise a video block covering a location (xCb-1, yCb-1+(cbHeight<<a)) and a video block covering a location (xCb-1+(cbWidth<<a), yCb-1), wherein (xCb, yCb) is a location of an upper-left sample of the current video block, cbWidth and cbHeight are the width and height of the current video block, respectively, and a is determined using a cIdx of the current block, where cIdx is a variable specifying a color component index for the current block, and where the color component index of the current block indicates a color component of the current block is a luma component. 14. A non-transitory computer-readable storage medium characterized in that it stores instructions that cause a processor to: determine, during a conversion between a current video block, which is encoded in a combined intra- and inter-prediction mode, of video data and a bitstream, a pair of weights comprising a first weight for a first prediction result of the current video block and a second weight for a second prediction result of the current video block, based on one or more video blocks neighboring the current video block, wherein the first prediction result is generated by an intra-prediction mode and the second prediction result is generated by an inter-prediction mode; and determine a prediction result of the current block based on a weighted sum of the first prediction result and the second prediction result; and perform the conversion based on the prediction result. wherein the weight pair is determined according to a prediction mode of the one or more neighboring video blocks of the current video block, wherein when at least one neighboring video block of the one or more neighboring video blocks is coded with the combined intra- and inter-prediction mode, the at least one neighboring video block is treated as a video block coded with an inter-prediction mode that is a non-intra-prediction mode, wherein the one or more neighboring video blocks comprise a video block covering a location (xCb-1, yCb-1+(cbHeight<<a)) and a video block covering a location (xCb-1+(cbWidth<<a), yCb-1), wherein (xCb, yCb) is a location of an upper left sample of the current video block, cbWidth and cbHeight are the width and height of the current video block respectively, and a is determined using a cIdx of the current block, wherein cIdx is a variable specifying a color component index for the current block, and where the color component index of the current block indicates a color component of the current block is a luma component. 15. A non-transitory computer-readable recording medium that stores a bitstream of data of a video that is generated by a method performed by a video processing apparatus, the method comprising: determining, for a current video block that is encoded in a combined intra- and inter-prediction mode, a pair of weights comprising a first weight for a first prediction result of the current video block and a second weight for a second prediction result of the current video block, based on one or more video blocks neighboring the current video block, wherein the first prediction result is generated by an intra-prediction mode and the second prediction result is generated by an inter-prediction mode; and determining a prediction result of the current block based on a weighted sum of the first prediction result and the second prediction result; and generating the bitstream based on the prediction result. wherein the weight pair is determined according to a prediction mode of the one or more neighboring video blocks of the current video block, wherein when at least one neighboring video block of the one or more neighboring video blocks is coded with the combined intra- and inter-prediction mode, the at least one neighboring video block is treated as a video block coded with an inter-prediction mode that is a non-intra-prediction mode, wherein the one or more neighboring video blocks comprise a video block covering a location (xCb-1, yCb-1+(cbHeight<<a)) and a video block covering a location (xCb-1+(cbWidth<<a), yCb-1), wherein (xCb, yCb) is a location of a top-left sample of the current video block, cbWidth and cbHeight are the width and height of the current video block, respectively, and a is determined using a cIdx of the current block, wherein cIdx is a variable specifying a color component index for the current block, and where the color component index of the current block indicates a color component of the current block is a luma component.